Flow of Red Blood Cells in Stenosed Microvessels

NASA Astrophysics Data System (ADS)

Vahidkhah, Koohyar; Balogh, Peter; Bagchi, Prosenjit

2016-06-01

A computational study is presented on the flow of deformable red blood cells in stenosed microvessels. It is observed that the Fahraeus-Lindqvist effect is significantly enhanced due to the presence of a stenosis. The apparent viscosity of blood is observed to increase by several folds when compared to non-stenosed vessels. An asymmetric distribution of the red blood cells, caused by geometric focusing in stenosed vessels, is observed to play a major role in the enhancement. The asymmetry in cell distribution also results in an asymmetry in average velocity and wall shear stress along the length of the stenosis. The discrete motion of the cells causes large time-dependent fluctuations in flow properties. The root-mean-square of flow rate fluctuations could be an order of magnitude higher than that in non-stenosed vessels. Several folds increase in Eulerian velocity fluctuation is also observed in the vicinity of the stenosis. Surprisingly, a transient flow reversal is observed upstream a stenosis but not downstream. The asymmetry and fluctuations in flow quantities and the flow reversal would not occur in absence of the cells. It is concluded that the flow physics and its physiological consequences are significantly different in micro- versus macrovascular stenosis.

Electrocapturing flow cell

DOEpatents

Morozov, Victor [Manassas, VA

2011-04-05

A flow cell for electrophoretically-assisted capturing analytes from a flow. The flow cell includes a specimen chamber, a first membrane, a second membrane, a first electrode chamber, and a second electrode chamber. The specimen chamber may have a sample inlet and a sample outlet. A first portion of the first membrane may be coupled to a first portion of the specimen chamber. A first portion of the second membrane may be coupled to a second portion of the specimen chamber. The first electrode chamber may be configured to accept a charge. A portion of the first electrode chamber may be coupled to a second portion of the first membrane. A second electrode chamber may be configured to accept an opposite charge. A portion of the second electrode chamber may be coupled to a second portion of the second membrane.

An experimental study of mushroom shaped stall cells. [on finite wings with separated flow

NASA Technical Reports Server (NTRS)

Winkelmann, A. E.

1982-01-01

Surface patterns characterized by a pair of counter-rotating swirls have been observed in connection with the conduction of surface flow visualization experiments involving test geometries with separated flows. An example of this phenomenon occurring on a finite wing with trailing edge stall has been referred to by Winkelmann and Barlow (1980) as 'mushroom shaped'. A description is presented of a collection of experimental results which show or suggest the occurrence of mushroom shaped stall cells on a variety of test geometries. Investigations conducted with finite wings, airfoil models, and flat plates are considered, and attention is given to studies involving the use of bluff models, investigations of shock induced boundary layer separation, and mushroom shaped patterns observed in a number of miscellaneous cases. It is concluded that the mushroom shaped stall cell appears commonly in separated flow regions.

Studying circulating prostate cancer cells by in-vivo flow cytometer

NASA Astrophysics Data System (ADS)

Guo, Jin; Gu, Zhengqin; Chen, Tong; Wang, Cheng; Wei, Xunbin

2012-03-01

Prostate cancer is the most common malignancy in American men and the second leading cause of deaths from cancer, after lung cancer. The tumor usually grows slowly and remains confined to the gland for many years. As the cancer advances, however, it can metastasize throughout other areas of the body, such as the bones, lungs, and liver. Surgical resection, hormonal therapy, chemotherapy and radiation therapy are the foundation of current prostate cancer therapies. Treatments for prostate cause both short- and long-term side effects that may be difficult to accept. Molecular mechanisms of prostate cancer metastasis need to be understood better and new therapies must be developed to selectively target to unique characteristics of cancer cell growth and metastasis. We have developed the "in vivo microscopy" to study the mechanisms that govern prostate cancer cell spread through the microenvironment in vivo in real-time confocal near-infrared fluorescence imaging. A recently developed "in vivo flow cytometer" and optical imaging are used to assess prostate cancer cell spreading and the circulation kinetics of prostate cancer cells. We have measured the depletion kinetics of cancer cells with different metastatic potential. Interestingly, more invasive PC-3 prostate cancer cells are depleted faster from the circulation than LNCaP cells.

Fuel cell with internal flow control

DOEpatents

Haltiner, Jr., Karl J.; Venkiteswaran, Arun [Karnataka, IN

2012-06-12

A fuel cell stack is provided with a plurality of fuel cell cassettes where each fuel cell cassette has a fuel cell with an anode and cathode. The fuel cell stack includes an anode supply chimney for supplying fuel to the anode of each fuel cell cassette, an anode return chimney for removing anode exhaust from the anode of each fuel cell cassette, a cathode supply chimney for supplying oxidant to the cathode of each fuel cell cassette, and a cathode return chimney for removing cathode exhaust from the cathode of each fuel cell cassette. A first fuel cell cassette includes a flow control member disposed between the anode supply chimney and the anode return chimney or between the cathode supply chimney and the cathode return chimney such that the flow control member provides a flow restriction different from at least one other fuel cell cassettes.

Blood flow and blood cell interactions and migration in microvessels

NASA Astrophysics Data System (ADS)

Fedosov, Dmitry; Fornleitner, Julia; Gompper, Gerhard

2011-11-01

Blood flow in microcirculation plays a fundamental role in a wide range of physiological processes and pathologies in the organism. To understand and, if necessary, manipulate the course of these processes it is essential to investigate blood flow under realistic conditions including deformability of blood cells, their interactions, and behavior in the complex microvascular network which is characteristic for the microcirculation. We employ the Dissipative Particle Dynamics method to model blood as a suspension of deformable cells represented by a viscoelastic spring-network which incorporates appropriate mechanical and rheological cell-membrane properties. Blood flow is investigated in idealized geometries. In particular, migration of blood cells and their distribution in blood flow are studied with respect to various conditions such as hematocrit, flow rate, red blood cell aggregation. Physical mechanisms which govern cell migration in microcirculation and, in particular, margination of white blood cells towards the vessel wall, will be discussed. In addition, we characterize blood flow dynamics and quantify hemodynamic resistance. D.F. acknowledges the Humboldt Foundation for financial support.

Study of flow behavior in all-vanadium redox flow battery using spatially resolved voltage distribution

NASA Astrophysics Data System (ADS)

Bhattarai, Arjun; Wai, Nyunt; Schweiss, Rüdiger; Whitehead, Adam; Scherer, Günther G.; Ghimire, Purna C.; Nguyen, Tam D.; Hng, Huey Hoon

2017-08-01

Uniform flow distribution through the porous electrodes in a flow battery cell is very important for reducing Ohmic and mass transport polarization. A segmented cell approach can be used to obtain in-situ information on flow behaviour, through the local voltage or current mapping. Lateral flow of current within the thick felts in the flow battery can hamper the interpretation of the data. In this study, a new method of segmenting a conventional flow cell is introduced, which for the first time, splits up both the porous felt as well as the current collector. This dual segmentation results in higher resolution and distinct separation of voltages between flow inlet to outlet. To study the flow behavior for an undivided felt, monitoring the OCV is found to be a reliable method, instead of voltage or current mapping during charging and discharging. Our approach to segmentation is simple and applicable to any size of the cell.

Intracellular fluid flow in rapidly moving cells

PubMed Central

Keren, Kinneret; Yam, Patricia T.; Kinkhabwala, Anika; Mogilner, Alex; Theriot, Julie A.

2010-01-01

Cytosolic fluid dynamics have been implicated in cell motility1–5 because of the hydrodynamic forces they induce and because of their influence on transport of components of the actin machinery to the leading edge. To investigate the existence and the direction of fluid flow in rapidly moving cells, we introduced inert quantum dots into the lamellipodia of fish epithelial keratocytes and analysed their distribution and motion. Our results indicate that fluid flow is directed from the cell body towards the leading edge in the cell frame of reference, at about 40% of cell speed. We propose that this forward-directed flow is driven by increased hydrostatic pressure generated at the rear of the cell by myosin contraction, and show that inhibition of myosin II activity by blebbistatin reverses the direction of fluid flow and leads to a decrease in keratocyte speed. We present a physical model for fluid pressure and flow in moving cells that quantitatively accounts for our experimental data. PMID:19767741

Depletion kinetics of circulating prostate cancer cells studied by in vivo flow cytometer

NASA Astrophysics Data System (ADS)

Liu, Guangda; Guo, Jin; Li, Yan; Chen, Yun; Gu, Zhengqin; Chen, Tong; Wang, Cheng; Wei, Xunbin

2010-11-01

Prostate cancer is the most common malignancy in American men and the second leading cause of deaths from cancer, after lung cancer. The tumor usually grows slowly and remains confined to the gland for many years. During this time, the tumor produces little or no symptoms or outward signs. As the cancer advances, however, it can metastasize throughout other areas of the body, such as the bones, lungs, and liver. Surgical resection, hormonal therapy, chemotherapy and radiation therapy are the foundation of current prostate cancer therapies. Treatments for prostate cause both short- and long-term side effects that may be difficult to accept. Molecular mechanisms of prostate cancer metastasis need to be understood better and new therapies must be developed to selectively target to unique characteristics of cancer cell growth and metastasis. We have developed the "in vivo microscopy" to study the mechanisms that govern prostate cancer cell spread through the microenvironment in vivo in real-time confocal nearinfrared fluorescence imaging. A recently developed "in vivo flow cytometer" and optical imaging are used to assess prostate cancer cell spreading and the circulation kinetics of prostate cancer cells. A real- time quantitative monitoring of circulating prostate cancer cells by the in vivo flow cytometer will be useful to assess the effectiveness of the potential therapeutic interventions.

Numerical Study of the Buoyancy-Driven Flow in a Four-Electrode Rectangular Electrochemical Cell

NASA Astrophysics Data System (ADS)

Sun, Zhanyu; Agafonov, Vadim; Rice, Catherine; Bindler, Jacob

2009-11-01

Two-dimensional numerical simulation is done on the buoyancy-driven flow in a four-electrode rectangular electrochemical cell. Two kinds of electrode layouts, the anode-cathode-cathode-anode (ACCA) and the cathode-anode-anode-cathode (CAAC) layouts, are studied. In the ACCA layout, the two anodes are placed close to the channel outlets while the two cathodes are located between the two anodes. The CAAC layout can be converted from the ACCA layout by applying higher electric potential on the two middle electrodes. Density gradient was generated by the electrodic reaction I3^-+2e^- =3I^-. When the electrochemical cell is accelerated axially, buoyancy-driven flow occurs. In our model, electro-neutrality is assumed except at the electrodes. The Navier-Stokes equations with the Boussinesq approximation and the Nernst-Planck equations are employed to model the momentum and mass transports, respectively. It is found that under a given axial acceleration, the electrolyte density between the two middle electrodes determines the bulk flow through the electrochemical cell. The cathodic current difference is found to be able to measure the applied acceleration. Other important electro-hydrodynamic characteristics are also discussed.

Interstitial flow influences direction of tumor cell migration through competing mechanisms

PubMed Central

Polacheck, William J.; Charest, Joseph L.; Kamm, Roger D.

2011-01-01

Interstitial flow is the convective transport of fluid through tissue extracellular matrix. This creeping fluid flow has been shown to affect the morphology and migration of cells such as fibroblasts, cancer cells, endothelial cells, and mesenchymal stem cells. A microfluidic cell culture system was designed to apply stable pressure gradients and fluid flow and allow direct visualization of transient responses of cells seeded in a 3D collagen type I scaffold. We used this system to examine the effects of interstitial flow on cancer cell morphology and migration and to extend previous studies showing that interstitial flow increases the metastatic potential of MDA-MB-435S melanoma cells [Shields J, et al. (2007) Cancer Cell 11:526–538]. Using a breast carcinoma line (MDA-MB-231) we also observed cell migration along streamlines in the presence of flow; however, we further demonstrated that the strength of the flow as well as the cell density determined directional bias of migration along the streamline. In particular, we found that cells either at high seeding density or with the CCR-7 receptor inhibited migration against, rather than with the flow. We provide further evidence that CCR7-dependent autologous chemotaxis is the mechanism that leads to migration with the flow, but also demonstrate a competing CCR7-independent mechanism that causes migration against the flow. Data from experiments investigating the effects of cell concentration, interstitial flow rate, receptor activity, and focal adhesion kinase phosphorylation support our hypothesis that the competing stimulus is integrin mediated. This mechanism may play an important role in development of metastatic disease. PMID:21690404

Recirculation cells for granular flow in cylindrical rotating tumblers

NASA Astrophysics Data System (ADS)

D'Ortona, Umberto; Thomas, Nathalie; Lueptow, Richard M.

2018-05-01

To better understand the velocity field and flowing layer structure, we have performed a detailed discrete element method study of the flow of monodisperse particles in a partially filled three-dimensional cylindrical rotating tumblers. Similar to what occurs near the poles in spherical and conical tumblers, recirculation cells (secondary flows) develop near the flat endwalls of a cylindrical tumbler in which particles near the surface drift axially toward the endwall, while particles deeper in the flowing layer drift axially toward the midlength of the tumbler. Another recirculation cell with the opposite sense develops next to each endwall recirculation cell, extending to the midlength of the tumbler. For a long enough tumbler, each endwall cell is about one quarter of the tumbler diameter in length. Endwall cells are insensitive to tumbler length and relatively insensitive to rotation speed (so long as the flowing layer remains flat and continuously flowing) or fill level (from 25% to 50% full). However, for shorter tumblers (0.5 to 1.0 length/diameter aspect ratio) the endwall cell size does not change much, while center cells reduce their size and eventually disappear for the shortest tumblers. For longer tumblers (length/diameter aspect ratio larger than 2), a stagnation zone appears in between the central cells. These results provide insight into the mixing of monodisperse particles in rotating cylindrical tumblers as well as the frictional effects of the tumbler endwalls.

Microconfined flow behavior of red blood cells.

PubMed

Tomaiuolo, Giovanna; Lanotte, Luca; D'Apolito, Rosa; Cassinese, Antonio; Guido, Stefano

2016-01-01

Red blood cells (RBCs) perform essential functions in human body, such as gas exchange between blood and tissues, thanks to their ability to deform and flow in the microvascular network. The high RBC deformability is mainly due to the viscoelastic properties of the cell membrane. Since an impaired RBC deformability could be found in some diseases, such as malaria, sickle cell anemia, diabetes and hereditary disorders, there is the need to provide further insight into measurement of RBC deformability in a physiologically relevant flow field. Here, RBCs deformability has been studied in terms of the minimum apparent plasma-layer thickness by using high-speed video microscopy of RBCs flowing in cylindrical glass capillaries. An in vitro systematic microfluidic investigation of RBCs in micro-confined conditions has been performed, resulting in the determination of the RBCs time recovery constant, RBC volume and surface area and RBC membrane shear elastic modulus and surface viscosity. It has been noticed that the deformability of RBCs induces cells aggregation during flow in microcapillaries, allowing the formation of clusters of cells. Overall, our results provide a novel technique to estimate RBC deformability and also RBCs collective behavior, which can be used for the analysis of pathological RBCs, for which reliable quantitative methods are still lacking. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Parallel-plate Flow Chamber and Continuous Flow Circuit to Evaluate Endothelial Progenitor Cells under Laminar Flow Shear Stress

PubMed Central

Lane, Whitney O.; Jantzen, Alexandra E.; Carlon, Tim A.; Jamiolkowski, Ryan M.; Grenet, Justin E.; Ley, Melissa M.; Haseltine, Justin M.; Galinat, Lauren J.; Lin, Fu-Hsiung; Allen, Jason D.; Truskey, George A.; Achneck, Hardean E.

2012-01-01

The overall goal of this method is to describe a technique to subject adherent cells to laminar flow conditions and evaluate their response to well quantifiable fluid shear stresses1. Our flow chamber design and flow circuit (Fig. 1) contains a transparent viewing region that enables testing of cell adhesion and imaging of cell morphology immediately before flow (Fig. 11A, B), at various time points during flow (Fig. 11C), and after flow (Fig. 11D). These experiments are illustrated with human umbilical cord blood-derived endothelial progenitor cells (EPCs) and porcine EPCs2,3. This method is also applicable to other adherent cell types, e.g. smooth muscle cells (SMCs) or fibroblasts. The chamber and all parts of the circuit are easily sterilized with steam autoclaving. In contrast to other chambers, e.g. microfluidic chambers, large numbers of cells (> 1 million depending on cell size) can be recovered after the flow experiment under sterile conditions for cell culture or other experiments, e.g. DNA or RNA extraction, or immunohistochemistry (Fig. 11E), or scanning electron microscopy5. The shear stress can be adjusted by varying the flow rate of the perfusate, the fluid viscosity, or the channel height and width. The latter can reduce fluid volume or cell needs while ensuring that one-dimensional flow is maintained. It is not necessary to measure chamber height between experiments, since the chamber height does not depend on the use of gaskets, which greatly increases the ease of multiple experiments. Furthermore, the circuit design easily enables the collection of perfusate samples for analysis and/or quantification of metabolites secreted by cells under fluid shear stress exposure, e.g. nitric oxide (Fig. 12)6. PMID:22297325

Co-flow planar SOFC fuel cell stack

DOEpatents

Chung, Brandon W.; Pham, Ai Quoc; Glass, Robert S.

2004-11-30

A co-flow planar solid oxide fuel cell stack with an integral, internal manifold and a casing/holder to separately seal the cell. This construction improves sealing and gas flow, and provides for easy manifolding of cell stacks. In addition, the stack construction has the potential for an improved durability and operation with an additional increase in cell efficiency. The co-flow arrangement can be effectively utilized in other electrochemical systems requiring gas-proof separation of gases.

Long waves in parallel flow in Hele-Shaw cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeybek, M.; Yortsos, Y.C.

During the past several years the flow of immiscible flow in Hele-Shaw cells and porous media has been investigated extensively. Of particular interest to most studies has been frontal displacement, specifically viscous fingering instabilities and finger growth. The practical ramifications regarding oil recovery, as well as many other industrial processes in porous media, have served as the primary driving force for most of these investigations. By contrast, little attention has been paid to the motion of lateral fluid interface, which are parallel to the main flow direction. Parallel flow is an often encountered, although much overlooked regime. The evolution ofmore » fluid interfaces in parallel flow in Hele-Shaw cells is studied both theoretically and experimentally in the large capillary number limit. It is shown that such interfaces support wave motion, the amplitude of which for long waves is governed by the KdV equation. Experiments are conducted in a long Hele-Shaw cell that validate the theory in the symmetric case. 35 refs., 16 figs.« less

Studying depletion kinetics of circulating prostate cancer cells by in vivo flow cytometer

NASA Astrophysics Data System (ADS)

Liu, Guangda; Gu, Zhengqin; Guo, Jin; Li, Yan; Chen, Yun; Chen, Tong; Wang, Cheng; Wei, Xunbin

2011-03-01

Prostate cancer is the most common malignancy in American men and the second leading cause of deaths from cancer, after lung cancer. The tumor usually grows slowly and remains confined to the gland for many years. During this time, the tumor produces little or no symptoms or outward signs. As the cancer advances, however, it can metastasize throughout other areas of the body, such as the bones, lungs, and liver. Surgical resection, hormonal therapy, chemotherapy and radiation therapy are the foundation of current prostate cancer therapies. Treatments for prostate cause both short- and long-term side effects that may be difficult to accept. Molecular mechanisms of prostate cancer metastasis need to be understood better and new therapies must be developed to selectively target to unique characteristics of cancer cell growth and metastasis. We have developed the "in vivo microscopy" to study the mechanisms that govern prostate cancer cell spread through the microenvironment in vivo in real-time confocal near-infrared fluorescence imaging. A recently developed "in vivo flow cytometer" and optical imaging are used to assess prostate cancer cell spreading and the circulation kinetics of prostate cancer cells. A real- time quantitative monitoring of circulating prostate cancer cells by the in vivo flow cytometer will be useful to assess the effectiveness of the potential therapeutic interventions.

Streak Imaging Flow Cytometer for Rare Cell Analysis.

PubMed

Balsam, Joshua; Bruck, Hugh Alan; Ossandon, Miguel; Prickril, Ben; Rasooly, Avraham

2017-01-01

There is a need for simple and affordable techniques for cytology for clinical applications, especially for point-of-care (POC) medical diagnostics in resource-poor settings. However, this often requires adapting expensive and complex laboratory-based techniques that often require significant power and are too massive to transport easily. One such technique is flow cytometry, which has great potential for modification due to the simplicity of the principle of optical tracking of cells. However, it is limited in that regard due to the flow focusing technique used to isolate cells for optical detection. This technique inherently reduces the flow rate and is therefore unsuitable for rapid detection of rare cells which require large volume for analysis.To address these limitations, we developed a low-cost, mobile flow cytometer based on streak imaging. In our new configuration we utilize a simple webcam for optical detection over a large area associated with a wide-field flow cell. The new flow cell is capable of larger volume and higher throughput fluorescence detection of rare cells than the flow cells with hydrodynamic focusing used in conventional flow cytometry. The webcam is an inexpensive, commercially available system, and for fluorescence analysis we use a 1 W 450 nm blue laser to excite Syto-9 stained cells with emission at 535 nm. We were able to detect low concentrations of stained cells at high flow rates of 10 mL/min, which is suitable for rapidly analyzing larger specimen volumes to detect rare cells at appropriate concentration levels. The new rapid detection capabilities, combined with the simplicity and low cost of this device, suggest a potential for clinical POC flow cytometry in resource-poor settings associated with global health.

Blood cell interactions and segregation in flow.

PubMed

Munn, Lance L; Dupin, Michael M

2008-04-01

For more than a century, pioneering researchers have been using novel experimental and computational approaches to probe the mysteries of blood flow. Thanks to their efforts, we know that blood cells generally prefer to migrate to the axis of flow, that red and white cells segregate in flow, and that cell deformability and their tendency to reversibly aggregate contribute to the non-Newtonian nature of this unique fluid. All of these properties have beneficial physiological consequences, allowing blood to perform a variety of critical functions. Our current understanding of these unusual flow properties of blood have been made possible by the ingenuity and diligence of a number of researchers, including Harry Goldsmith, who developed novel technologies to visualize and quantify the flow of blood at the level of individual cells. Here we summarize efforts in our lab to continue this tradition and to further our understanding of how blood cells interact with each other and with the blood vessel wall.

Blood Cell Interactions and Segregation in Flow

PubMed Central

Munn, Lance L.; Dupin, Michael M.

2009-01-01

For more than a century, pioneering researchers have been using novel experimental and computational approaches to probe the mysteries of blood flow. Thanks to their efforts, we know that blood cells generally prefer to migrate to the axis of flow, that red and white cells segregate in flow, and that cell deformability and their tendency to reversibly aggregate contribute to the non-Newtonian nature of this unique fluid. All of these properties have beneficial physiological consequences, allowing blood to perform a variety of critical functions. Our current understanding of these unusual flow properties of blood have been made possible by the ingenuity and diligence of a number of researchers, including Harry Goldsmith, who developed novel technologies to visualize and quantify the flow of blood at the level of individual cells. Here we summarize efforts in our lab to continue this tradition and to further our understanding of how blood cells interact with each other and with the blood vessel wall. PMID:18188702

Injectable Solid Peptide Hydrogel as Cell Carrier: Effects of Shear Flow on Hydrogel and Cell Payload

PubMed Central

Yan, Congqi; Mackay, Michael E.; Czymmek, Kirk; Nagarkar, Radhika P.; Schneider, Joel P.; Pochan, Darrin J.

2012-01-01

β-hairpin peptide-based hydrogels are a class of injectable solid hydrogels that can deliver encapsulated cells or molecular therapies to a target site via syringe or catheter injection as a carrier material. These physical hydrogels can shear-thin and consequently flow as a low-viscosity material under a sufficient shear stress but immediately recover back into a solid upon removal of the stress, allowing them to be injected as preformed gel solids. Hydrogel behavior during flow was studied in a cylindrical capillary geometry that mimicked the actual situation of injection through a syringe needle in order to quantify effects of shear-thin injection delivery on hydrogel flow behavior and encapsulated cell payloads. It was observed that all β-hairpin peptide hydrogels investigated displayed a promising flow profile for injectable cell delivery: a central wide plug flow region where gel material and cell payloads experienced little or no shear rate and a narrow shear zone close to the capillary wall where gel and cells were subject to shear deformation. The width of the plug flow region was found to be weakly dependent on hydrogel rigidity and flow rate. Live-dead assays were performed on encapsulated MG63 cells three hours after injection flow and revealed that shear-thin delivery through the capillary had little impact on cell viability and the spatial distribution of encapsulated cell payloads. These observations help us to fundamentally understand how the gels flow during injection through a thin catheter and how they immediately restore mechanically and morphologically relative to pre-flow, static gels. PMID:22390812

Ellipsoidal cell flow system

DOEpatents

Salzman, Gary C.; Mullaney, Paul F.

1976-01-01

The disclosure relates to a system incorporating an ellipsoidal flow chamber having light reflective walls for low level light detection in practicing cellular analysis. The system increases signal-to-noise ratio by a factor of ten over prior art systems. In operation, laser light passes through the primary focus of the ellipsoid. A controlled flow of cells simultaneously passes through this focus so that the laser light impinges on the cells and is modulated by the cells. The reflective walls of the ellipsoid reflect the cell-modulated light to the secondary focus of the ellipsoid. A tapered light guide at the secondary focus picks up a substantial portion of modulated reflective light and directs it onto a light detector to produce a signal. The signal is processed to obtain the intensity distribution of the modulated light and hence sought after characteristics of the cells. In addition, cells may be dyed so as to fluoresce in response to the laser light and their fluorescence may be processed as cell-modulated light above described. A light discriminating filter would be used to distinguish reflected modulated laser light from reflected fluorescent light.

Flow regimes in a trapped vortex cell

NASA Astrophysics Data System (ADS)

Lasagna, D.; Iuso, G.

2016-03-01

This paper presents results of an experimental investigation on the flow in a trapped vortex cell, embedded into a flat plate, and interacting with a zero-pressure-gradient boundary layer. The objective of the work is to describe the flow features and elucidate some of the governing physical mechanisms, in the light of recent investigations on flow separation control using vortex cells. Hot-wire velocity measurements of the shear layer bounding the cell and of the boundary layers upstream and downstream are reported, together with spectral and correlation analyses of wall-pressure fluctuation measurements. Smoke flow visualisations provide qualitative insight into some relevant features of the internal flow, namely a large-scale flow unsteadiness and possible mechanisms driving the rotation of the vortex core. Results are presented for two very different regimes: a low-Reynolds-number case where the incoming boundary layer is laminar and its momentum thickness is small compared to the cell opening, and a moderately high-Reynolds-number case, where the incoming boundary layer is turbulent and the ratio between the momentum thickness and the opening length is significantly larger than in the first case. Implications of the present findings to flow control applications of trapped vortex cells are also discussed.

Malignant human cell transformation of Marcellus Shale gas drilling flow back water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Yixin; Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987; Chen, Tingting

The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation are known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these wastewaters, flow back waters from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy/energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carriedmore » out to define the LC{sub 50} values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found to be elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6 weeks with flow back waters produced colony formation in soft agar that was concentration dependent. In addition, flow back water-transformed BEAS-2B cells show better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. - Highlights: • This is the first report of potential cytotoxicity and transforming activity of Marcellus shale gas mining flow back to mammalian cells. • Barium and Strontium were elevated in flow back water exposed cells. • Flow back water malignantly transformed cells and formed tumor in athymic nude mice. • Flow back transformed cells exhibited altered transcriptome with dysregulated cell migration pathway and adherent junction pathway.« less

Growth of Myxococcus xanthus in continuous-flow-cell bioreactors as a method for studying development.

PubMed

Smaldone, Gregory T; Jin, Yujie; Whitfield, Damion L; Mu, Andrew Y; Wong, Edward C; Wuertz, Stefan; Singer, Mitchell

2014-04-01

Nutrient sensors and developmental timers are two classes of genes vital to the establishment of early development in the social soil bacterium Myxococcus xanthus. The products of these genes trigger and regulate the earliest events that drive the colony from a vegetative state to aggregates, which ultimately leads to the formation of fruiting bodies and the cellular differentiation of the individual cells. In order to more accurately identify the genes and pathways involved in the initiation of this multicellular developmental program in M. xanthus, we adapted a method of growing vegetative populations within a constant controllable environment by using flow cell bioreactors, or flow cells. By establishing an M. xanthus community within a flow cell, we are able to test developmental responses to changes in the environment with fewer concerns for effects due to nutrient depletion or bacterial waste production. This approach allows for greater sensitivity in investigating communal environmental responses, such as nutrient sensing. To demonstrate the versatility of our growth environment, we carried out time-lapse confocal laser scanning microscopy to visualize M. xanthus biofilm growth and fruiting body development, as well as fluorescence staining of exopolysaccharides deposited by biofilms. We also employed the flow cells in a nutrient titration to determine the minimum concentration required to sustain vegetative growth. Our data show that by using a flow cell, M. xanthus can be held in a vegetative growth state at low nutrient concentrations for long periods, and then, by slightly decreasing the nutrient concentration, cells can be allowed to initiate the developmental program.

Pinched-flow hydrodynamic stretching of single-cells.

PubMed

Dudani, Jaideep S; Gossett, Daniel R; Tse, Henry T K; Di Carlo, Dino

2013-09-21

Reorganization of cytoskeletal networks, condensation and decondensation of chromatin, and other whole cell structural changes often accompany changes in cell state and can reflect underlying disease processes. As such, the observable mechanical properties, or mechanophenotype, which is closely linked to intracellular architecture, can be a useful label-free biomarker of disease. In order to make use of this biomarker, a tool to measure cell mechanical properties should accurately characterize clinical specimens that consist of heterogeneous cell populations or contain small diseased subpopulations. Because of the heterogeneity and potential for rare populations in clinical samples, single-cell, high-throughput assays are ideally suited. Hydrodynamic stretching has recently emerged as a powerful method for carrying out mechanical phenotyping. Importantly, this method operates independently of molecular probes, reducing cost and sample preparation time, and yields information-rich signatures of cell populations through significant image analysis automation, promoting more widespread adoption. In this work, we present an alternative mode of hydrodynamic stretching where inertially-focused cells are squeezed in flow by perpendicular high-speed pinch flows that are extracted from the single inputted cell suspension. The pinched-flow stretching method reveals expected differences in cell deformability in two model systems. Furthermore, hydraulic circuit design is used to tune stretching forces and carry out multiple stretching modes (pinched-flow and extensional) in the same microfluidic channel with a single fluid input. The ability to create a self-sheathing flow from a single input solution should have general utility for other cytometry systems and the pinched-flow design enables an order of magnitude higher throughput (65,000 cells s(-1)) compared to our previously reported deformability cytometry method, which will be especially useful for identification of rare

Modeling studies of electrolyte flow and bubble behavior in advanced Hall cells

NASA Astrophysics Data System (ADS)

Shekhar, R.; Evans, J. W.

Much research was performed in recent years by corporations and university/government labs on materials for use in advanced Hall-Heroult cells. Attention has focussed on materials for use as wettable cathodes and inert anodes and much was achieved in terms of material development. Comparatively less attention was devoted to how these materials might be incorporated in new or existing cells, i.e., to how the cells should be designed and redesigned, to take full advantage of these materials. The effort, supported by the U.S. Department of Energy, to address this issue, is described. The primary objectives are cell design where electrolyte flow can be managed to promote both the removal of the anode gas bubbles and the convection of dissolved alumina in the inter-electrode region, under conditions where the anode-cathode distance is small. The principal experimental tool was a water model consisting of a large tank in which simulated anodes can be suspended in either the horizontal or vertical configurations. Gas generation was by forcing compressed air through porous graphite and the fine bubbles characteristic of inert anodes were produced by adding butanol to the water. Velocities were measured using a laser Doppler velocimeter. Velocity measurements with two different anode designs (one that is flat and the other that has grooves) are presented. The results show that the electrode configuration has a significant effect on the fluid flow pattern in the inter-electrode region. Furthermore, it is shown that rapid fluid flow is obtained when the cell is operated with a submerged anode.

Novel multi-functional fluid flow device for studying cellular mechanotransduction

PubMed Central

Lyons, James S.; Iyer, Shama R.; Lovering, Richard M.; Ward, Christopher W.; Stains, Joseph P.

2016-01-01

Cells respond to their mechanical environment by initiating multiple mechanotransduction signaling pathways. Defects in mechanotransduction have been implicated in a number of pathologies; thus, there is need for convenient and efficient methods for studying the mechanisms underlying these processes. A widely used and accepted technique for mechanically stimulating cells in culture is the introduction of fluid flow on cell monolayers. Here, we describe a novel, multifunctional fluid flow device for exposing cells to fluid flow in culture. This device integrates with common lab equipment including routine cell culture plates and peristaltic pumps. Further, it allows the fluid flow treated cells to be examined with outcomes at the cell and molecular level. We validated the device using the biologic response of cultured UMR-106 osteoblast-like cells in comparison to a commercially available system of laminar sheer stress to track live cell calcium influx in response to fluid flow. In addition, we demonstrate the fluid flow-dependent activation of phospho-ERK in these cells, consistent with the findings in other fluid flow devices. This device provides a low cost, multi-functional alternative to currently available systems, while still providing the ability to generate physiologically relevant conditions for studying processes involved in mechanotransduction in vitro. PMID:27887728

Flow field measurements in the cell culture unit

NASA Technical Reports Server (NTRS)

Walker, Stephen; Wilder, Mike; Dimanlig, Arsenio; Jagger, Justin; Searby, Nancy

2002-01-01

The cell culture unit (CCU) is being designed to support cell growth for long-duration life science experiments on the International Space Station (ISS). The CCU is a perfused loop system that provides a fluid environment for controlled cell growth experiments within cell specimen chambers (CSCs), and is intended to accommodate diverse cell specimen types. Many of the functional requirements depend on the fluid flow field within the CSC (e.g., feeding and gas management). A design goal of the CCU is to match, within experimental limits, all environmental conditions, other than the effects of gravity on the cells, whether the hardware is in microgravity ( micro g), normal Earth gravity, or up to 2g on the ISS centrifuge. In order to achieve this goal, two steps are being taken. The first step is to characterize the environmental conditions of current 1g cell biology experiments being performed in laboratories using ground-based hardware. The second step is to ensure that the design of the CCU allows the fluid flow conditions found in 1g to be replicated from microgravity up to 2g. The techniques that are being used to take these steps include flow visualization, particle image velocimetry (PIV), and computational fluid dynamics (CFD). Flow visualization using the injection of dye has been used to gain a global perspective of the characteristics of the CSC flow field. To characterize laboratory cell culture conditions, PIV is being used to determine the flow field parameters of cell suspension cultures grown in Erlenmeyer flasks on orbital shakers. These measured parameters will be compared to PIV measurements in the CSCs to ensure that the flow field that cells encounter in CSCs is within the bounds determined for typical laboratory experiments. Using CFD, a detailed simulation is being developed to predict the flow field within the CSC for a wide variety of flow conditions, including microgravity environments. Results from all these measurements and analyses of the

High speed flow cytometric separation of viable cells

DOEpatents

Sasaki, D.T.; Van den Engh, G.J.; Buckie, A.M.

1995-11-14

Hematopoietic cell populations are separated to provide cell sets and subsets as viable cells with high purity and high yields, based on the number of original cells present in the mixture. High-speed flow cytometry is employed using light characteristics of the cells to separate the cells, where high flow speeds are used to reduce the sorting time.

High speed flow cytometric separation of viable cells

DOEpatents

Sasaki, Dennis T.; Van den Engh, Gerrit J.; Buckie, Anne-Marie

1995-01-01

Hematopoietic cell populations are separated to provide cell sets and subsets as viable cells with high purity and high yields, based on the number of original cells present in the mixture. High-speed flow cytometry is employed using light characteristics of the cells to separate the cells, where high flow speeds are used to reduce the sorting time.

Flow cytometric immunofluorescence of rat anterior pituitary cells

NASA Technical Reports Server (NTRS)

Hatfield, J. Michael; Hymer, W. C.

1985-01-01

A flow cytometric immunofluorescence technique was developed for the quantification of growth hormone, prolactin, and luteinizing hormone producing cells. The procedure is based on indirect-immunofluorescence of intracellular hormone using an EPICS V cell sorter and can objectively count 50,000 cells in about 3 minutes. It can be used to study the dynamics of pituitary cell populations under various physiological and pharmacological conditions.

Cytoplasmic Flow Enhances Organelle Dispersion in Eukaryotic Cells

NASA Astrophysics Data System (ADS)

Koslover, Elena; Mogre, Saurabh; Chan, Caleb; Theriot, Julie

The cytoplasm of a living cell is an active environment through which intracellular components move and mix. We explore, using theoretical modeling coupled with microrheological measurements, the efficiency of particle dispersion via different modes of transport within this active environment. In particular, we focus on the role of cytoplasmic flow over different scales in contributing to organelle transport within two different cell types. In motile neutrophil cells, we show that bulk fluid flow associated with rapid cell deformation enhances particle transport to and from the cell periphery. In narrow fungal hyphae, localized flows due to hydrodynamic entrainment are shown to contribute to optimally efficient organelle dispersion. Our results highlight the importance of non-traditional modes of transport associated with flow of the cytoplasmic fluid in the distribution of organelles throughout eukaryotic cells.

Interstitial flows promote an amoeboid cell phenotype and motility of breast cancer cells

NASA Astrophysics Data System (ADS)

Tung, Chih-Kuan; Huang, Yu Ling; Zheng, Angela; Wu, Mingming

2015-03-01

Lymph nodes, the drainage systems for interstitial flows, are clinically known to be the first metastatic sites of many cancer types including breast and prostate cancers. Here, we demonstrate that breast cancer cell morphology and motility is modulated by interstitial flows in a cell-ECM adhesion dependent manner. The average aspect ratios of the cells are significantly lower (or are more amoeboid like) in the presence of the flow in comparison to the case when the flow is absent. The addition of exogenous adhesion molecules within the extracellular matrix (type I collagen) enhances the overall aspect ratio (or are more mesenchymal like) of the cell population. Using measured cell trajectories, we find that the persistence of the amoeboid cells (aspect ratio less than 2.0) is shorter than that of mesenchymal cells. However, the maximum speed of the amoeboid cells is larger than that of mesenchymal cells. Together these findings provide the novel insight that interstitial flows promote amoeboid cell morphology and motility and highlight the plasticity of tumor cell motility in response to its biophysical environment. Supported by NIH Grant R21CA138366.

Fuel cell with metal screen flow-field

DOEpatents

Wilson, M.S.; Zawodzinski, C.

1998-08-25

A polymer electrolyte membrane (PEM) fuel cell is provided with electrodes supplied with a reactant on each side of a catalyzed membrane assembly (CMA). The fuel cell includes a metal mesh defining a rectangular flow-field pattern having an inlet at a first corner and an outlet at a second corner located on a diagonal from the first corner, wherein all flow paths from the inlet to the outlet through the square flow field pattern are equivalent to uniformly distribute the reactant over the CMA. In a preferred form of metal mesh, a square weave screen forms the flow-field pattern. In a particular characterization of the present invention, a bipolar plate electrically connects adjacent fuel cells, where the bipolar plate includes a thin metal foil having an anode side and a cathode side; a first metal mesh on the anode side of the thin metal foil; and a second metal mesh on the cathode side of the thin metal foil. In another characterization of the present invention, a cooling plate assembly cools adjacent fuel cells, where the cooling plate assembly includes an anode electrode and a cathode electrode formed of thin conducting foils; and a metal mesh flow field there between for distributing cooling water flow over the electrodes to remove heat generated by the fuel cells. 11 figs.

Fuel cell with metal screen flow-field

DOEpatents

Wilson, Mahlon S.; Zawodzinski, Christine

2001-01-01

A polymer electrolyte membrane (PEM) fuel cell is provided with electrodes supplied with a reactant on each side of a catalyzed membrane assembly (CMA). The fuel cell includes a metal mesh defining a rectangular flow-field pattern having an inlet at a first corner and an outlet at a second corner located on a diagonal from the first corner, wherein all flow paths from the inlet to the outlet through the square flow field pattern are equivalent to uniformly distribute the reactant over the CMA. In a preferred form of metal mesh, a square weave screen forms the flow-field pattern. In a particular characterization of the present invention, a bipolar plate electrically connects adjacent fuel cells, where the bipolar plate includes a thin metal foil having an anode side and a cathode side; a first metal mesh on the anode side of the thin metal foil; and a second metal mesh on the cathode side of the thin metal foil. In another characterization of the present invention, a cooling plate assembly cools adjacent fuel cells, where the cooling plate assembly includes an anode electrode and a cathode electrode formed of thin conducting foils; and a metal mesh flow field therebetween for distributing cooling water flow over the electrodes to remove heat generated by the fuel cells.

Fuel cell with metal screen flow-field

DOEpatents

Wilson, Mahlon S.; Zawodzinski, Christine

1998-01-01

A polymer electrolyte membrane (PEM) fuel cell is provided with electrodes supplied with a reactant on each side of a catalyzed membrane assembly (CMA). The fuel cell includes a metal mesh defining a rectangular flow-field pattern having an inlet at a first corner and an outlet at a second corner located on a diagonal from the first corner, wherein all flow paths from the inlet to the outlet through the square flow field pattern are equivalent to uniformly distribute the reactant over the CMA. In a preferred form of metal mesh, a square weave screen forms the flow-field pattern. In a particular characterization of the present invention, a bipolar plate electrically connects adjacent fuel cells, where the bipolar plate includes a thin metal foil having an anode side and a cathode side; a first metal mesh on the anode side of the thin metal foil; and a second metal mesh on the cathode side of the thin metal foil. In another characterization of the present invention, a cooling plate assembly cools adjacent fuel cells, where the cooling plate assembly includes an anode electrode and a cathode electrode formed of thin conducting foils; and a metal mesh flow field therebetween for distributing cooling water flow over the electrodes to remove heat generated by the fuel cells.

Free flow cell electrophoresis using zwitterionic buffer

NASA Technical Reports Server (NTRS)

Rodkey, R. Scott

1990-01-01

Studies of a zwitterionic buffer formulated for cell electrophoresis were done using the McDonnell-Douglas Continuous Flow Electrophoresis System. Standard buffers were analyzed for their stability in the electrical field and the results showed that both buffers tested were inherently unstable. Further, titration studies showed that the standards buffers buffered poorly at the pH employed for electrophoresis. The zwitterionic buffer buffered well at its nominal pH and was shown to be stable in the electrical field. Comparative studies of the buffer with standard cell separation buffers using formalin fixed rabbit and goose red blood cells showed that the zwitterionic buffer gave better resolution of the fixed cells. Studies with viable hybridoma cells showed that buffer Q supported cell viability equal to Hank's Balanced Salt Solution and that hybridoma cells in different stages of the growth cycle demonstrated reproducible differences in electrophoretic mobility.

Performance of PEM fuel cells stack as affected by number of cell and gas flow-rate

NASA Astrophysics Data System (ADS)

Syampurwadi, A.; Onggo, H.; Indriyati; Yudianti, R.

2017-03-01

The proton exchange membrane fuel cell (PEMFC) is a promising technology as an alternative green energy due to its high power density, low operating temperatures, low local emissions, quiet operation and fast start up-shutdown. In order to apply fuel cell as portable power supply, the performance investigation of small number of cells is needed. In this study, PEMFC stacks consisting of 1, 3, 5 and 7-cells with an active area of 25 cm2 per cell have been designed and developed. Their was evaluated in variation of gas flow rate. The membrane electrode assembly (MEA) was prepared by hot-pressing commercial gas diffusion electrodes (Pt loading 0.5 mg/cm2) on pre-treated Nafion 117 membrane. The stacks were constructed using bipolar plates in serpentine pattern and Z-type gas flow configuration. The experimental results were presented as polarization and power output curves which show the effects of varying number of cells and H2/O2 flow-rates on the PEMFC performance. The experimental results showed that not only number of cells and gas flow-rates affected the fuel cells performance, but also the operating temperature as a result of electrochemistry reaction inside the cell.

Rapid flow-induced responses in endothelial cells

NASA Technical Reports Server (NTRS)

Stamatas, G. N.; McIntire, L. V.

2001-01-01

Endothelial cells alter their morphology, growth rate, and metabolism in response to fluid shear stress. To study rapid flow-induced responses in the 3D endothelial cell morphology and calcium distribution, coupled fluorescence microscopy with optical sectioning, digital imaging, and numerical deconvolution techniques have been utilized. Results demonstrate that within the first minutes of flow application nuclear calcium is increasing. In the same time frame whole cell height and nuclear height are reduced by about 1 microm. Whole cell height changes may facilitate reduction of shear stress gradients on the luminal surface, whereas nuclear structural changes may be important for modulating endothelial growth rate and metabolism. To study the role of the cytoskeleton in these responses, endothelial cells have been treated with specific disrupters (acrylamide, cytochalasin D, and colchicine) of each of the cytoskeleton elements (intermediate filaments, microfilaments, and microtubules, respectively). None of these compounds had any effect on the shear-induced calcium response. Cytochalasin D and acrylamide did not affect the shear-induced nuclear morphology changes. Colchicine, however, completely abrogated the response, indicating that microtubules may be implicated in force transmission from the plasma membrane to the nucleus. A pedagogical model based on tensegrity theory principles is presented that is consistent with the results on the 3D endothelial morphology.

Oxygen-Mass-Flow Calibration Cell

NASA Technical Reports Server (NTRS)

Martin, Robert E.

1996-01-01

Proposed calibration standard for mass flow rate of oxygen based on conduction of oxygen ions through solid electrolyte membrane made of zirconia and heated to temperature of 1,000 degrees C. Flow of oxygen ions proportional to applied electric current. Unaffected by variations in temperature and pressure, and requires no measurement of volume. Calibration cell based on concept used to calibrate variety of medical and scientific instruments required to operate with precise rates of flow of oxygen.

Systematic misestimation of cell subpopulations by flow cytometry: a mathematical analysis.

PubMed

Petrunkina, A M; Harrison, R A P

2010-04-15

Various sources of variability in flow cytometric determination of cell concentration have previously been investigated with respect to andrologic applications. Although common aspects related to the variation between samples, variation between operators, and accuracy have been extensively studied, specific sources of false-count estimation have found less attention. In particular, a major and well-recognized source of misestimation of cell counts (i.e., contamination of the sample by non-sperm particles) has not to date been characterized in detail. We show here by means of original mathematical research that not only the cell counts but also the percentages of cells expressing different fluorescence patterns are affected by the presence of alien particles often neglected in studies involving flow cytometric characterization. We demonstrate that there is a systematic overestimation in the proportion of unstained (viable) cells detected by flow cytometry in cases where the non-sperm particles are not excluded from analysis by additional identification other than light-scatter characteristics. Moreover, we provide an exact mathematical estimate for the magnitude of this overestimation, and we discuss the consequences for diagnostic applications and studies on sperm physiology, specifically for studies on sperm capacitation and evaluation of cryopreserved semen. Finally, equations are derived for the correction of the flow cytometric values for use in practical applications. Copyright 2010 Elsevier Inc. All rights reserved.

Analytical and numerical study on cooling flow field designs performance of PEM fuel cell with variable heat flux

NASA Astrophysics Data System (ADS)

Afshari, Ebrahim; Ziaei-Rad, Masoud; Jahantigh, Nabi

2016-06-01

In PEM fuel cells, during electrochemical generation of electricity more than half of the chemical energy of hydrogen is converted to heat. This heat of reactions, if not exhausted properly, would impair the performance and durability of the cell. In general, large scale PEM fuel cells are cooled by liquid water that circulates through coolant flow channels formed in bipolar plates or in dedicated cooling plates. In this paper, a numerical method has been presented to study cooling and temperature distribution of a polymer membrane fuel cell stack. The heat flux on the cooling plate is variable. A three-dimensional model of fluid flow and heat transfer in cooling plates with 15 cm × 15 cm square area is considered and the performances of four different coolant flow field designs, parallel field and serpentine fields are compared in terms of maximum surface temperature, temperature uniformity and pressure drop characteristics. By comparing the results in two cases, the constant and variable heat flux, it is observed that applying constant heat flux instead of variable heat flux which is actually occurring in the fuel cells is not an accurate assumption. The numerical results indicated that the straight flow field model has temperature uniformity index and almost the same temperature difference with the serpentine models, while its pressure drop is less than all of the serpentine models. Another important advantage of this model is the much easier design and building than the spiral models.

Whole cell quenched flow analysis.

PubMed

Chiang, Ya-Yu; Haeri, Sina; Gizewski, Carsten; Stewart, Joanna D; Ehrhard, Peter; Shrimpton, John; Janasek, Dirk; West, Jonathan

2013-12-03

This paper describes a microfluidic quenched flow platform for the investigation of ligand-mediated cell surface processes with unprecedented temporal resolution. A roll-slip behavior caused by cell-wall-fluid coupling was documented and acts to minimize the compression and shear stresses experienced by the cell. This feature enables high-velocity (100-400 mm/s) operation without impacting the integrity of the cell membrane. In addition, rotation generates localized convection paths. This cell-driven micromixing effect causes the cell to become rapidly enveloped with ligands to saturate the surface receptors. High-speed imaging of the transport of a Janus particle and fictitious domain numerical simulations were used to predict millisecond-scale biochemical switching times. Dispersion in the incubation channel was characterized by microparticle image velocimetry and minimized by using a horizontal Hele-Shaw velocity profile in combination with vertical hydrodynamic focusing to achieve highly reproducible incubation times (CV = 3.6%). Microfluidic quenched flow was used to investigate the pY1131 autophosphorylation transition in the type I insulin-like growth factor receptor (IGF-1R). This predimerized receptor undergoes autophosphorylation within 100 ms of stimulation. Beyond this demonstration, the extreme temporal resolution can be used to gain new insights into the mechanisms underpinning a tremendous variety of important cell surface events.

A microfluidic fuel cell with flow-through porous electrodes.

PubMed

Kjeang, Erik; Michel, Raphaelle; Harrington, David A; Djilali, Ned; Sinton, David

2008-03-26

A microfluidic fuel cell architecture incorporating flow-through porous electrodes is demonstrated. The design is based on cross-flow of aqueous vanadium redox species through the electrodes into an orthogonally arranged co-laminar exit channel, where the waste solutions provide ionic charge transfer in a membraneless configuration. This flow-through architecture enables improved utilization of the three-dimensional active area inside the porous electrodes and provides enhanced rates of convective/diffusive transport without increasing the parasitic loss required to drive the flow. Prototype fuel cells are fabricated by rapid prototyping with total material cost estimated at 2 USD/unit. Improved performance as compared to previous microfluidic fuel cells is demonstrated, including power densities at room temperature up to 131 mW cm-2. In addition, high overall energy conversion efficiency is obtained through a combination of relatively high levels of fuel utilization and cell voltage. When operated at 1 microL min-1 flow rate, the fuel cell produced 20 mW cm-2 at 0.8 V combined with an active fuel utilization of 94%. Finally, we demonstrate in situ fuel and oxidant regeneration by running the flow-through architecture fuel cell in reverse.

Artificial Hair Cells for Sensing Flows

NASA Technical Reports Server (NTRS)

Chen, Jack

2007-01-01

The purpose of this article is to present additional information about the flow-velocity sensors described briefly in the immediately preceding article. As noted therein, these sensors can be characterized as artificial hair cells that implement an approximation of the sensory principle of flow-sensing cilia of fish: A cilium is bent by an amount proportional to the flow to which it is exposed. A nerve cell at the base of the cilium senses the flow by sensing the bending of the cilium. In an artificial hair cell, the artificial cilium is a microscopic cantilever beam, and the bending of an artificial cilium is measured by means of a strain gauge at its base (see Figure 1). Figure 2 presents cross sections of a representative sensor of this type at two different stages of its fabrication process. The process consists of relatively- low-temperature metallization, polymer-deposition, microfabrication, and surface-micromachining subprocesses, including plastic-deformation magnetic assembly (PDMA), which is described below. These subprocesses are suitable for a variety of substrate materials, including silicon, some glasses, and some polymers. Moreover, because it incorporates a polymeric supporting structure, this sensor is more robust, relative to its silicon-based counterparts.

Blood Flow through an Open-Celled Foam

NASA Astrophysics Data System (ADS)

Ortega, Jason; Maitland, Duncan

2011-11-01

The Hazen-Dupuit-Darcy (HDD) equation is commonly used in engineering applications to model the pressure gradient of flow through a porous media. One major advantage of this equation is that it simplifies the complex geometric details of the porous media into two coefficients: the permeability, K, and form factor, C. However through this simplification, the flow details within the porous media are no longer accessible, making it difficult to study the phenomena that contribute to changes in K and C due to clotting of blood flow. To obtain a more detailed understanding of blood flow through a porous media, a direct assessment of the complex interstitial geometry and flow is required. In this study, we solve the Navier-Stokes equations for Newtonian and non-Newtonian blood flow through an open-celled foam geometry obtained from a micro-CT scan. The nominal strut size of the foam sample is of O(10e-5) m and the corresponding Reynolds number based upon this length ranges up to O(10). Fitting the pressure gradient vs. Darcy velocity data with the HDD equation demonstrates that both viscous and inertial forces play an important role in the flow through the foam at these Reynolds numbers. Recirculation zones are observed to form in the wake of the pore struts, producing regions of flow characterized by both low shear rates and long fluid residence times, factors of which have been shown in previous studies to promote blood clotting.

Connexin 36 mediates blood cell flow in mouse pancreatic islets

PubMed Central

Short, Kurt W.; Head, W. Steve

2013-01-01

The insulin-secreting β-cells are contained within islets of Langerhans, which are highly vascularized. Blood cell flow rates through islets are glucose-dependent, even though there are no changes in blood cell flow within in the surrounding exocrine pancreas. This suggests a specific mechanism of glucose-regulated blood flow in the islet. Pancreatic islets respond to elevated glucose with synchronous pulses of electrical activity and insulin secretion across all β-cells in the islet. Connexin 36 (Cx36) gap junctions between islet β-cells mediate this synchronization, which is lost in Cx36 knockout mice (Cx36−/−). This leads to glucose intolerance in these mice, despite normal plasma insulin levels and insulin sensitivity. Thus, we sought to investigate whether the glucose-dependent changes in intraislet blood cell flow are also dependent on coordinated pulsatile electrical activity. We visualized and quantified blood cell flow using high-speed in vivo fluorescence imaging of labeled red blood cells and plasma. With the use of a live animal glucose clamp, blood cell flow was measured during either hypoglycemia (∼50 mg/dl) or hyperglycemia (∼300 mg/dl). In contrast to the large glucose-dependent islet blood velocity changes observed in wild-type mice, only minimal differences are observed in both Cx36+/− and Cx36−/− mice. This observation supports a novel model where intraislet blood cell flow is regulated by the coordinated electrical activity in the islet β-cells. Because Cx36 expression and function is reduced in type 2 diabetes, the resulting defect in intraislet blood cell flow regulation may also play a significant role in diabetic pathology. PMID:24326425

Design of a miniature flow cell for in situ x-ray imaging of redox flow batteries

NASA Astrophysics Data System (ADS)

Jervis, Rhodri; Brown, Leon D.; Neville, Tobias P.; Millichamp, Jason; Finegan, Donal P.; Heenan, Thomas M. M.; Brett, Dan J. L.; Shearing, Paul R.

2016-11-01

Flow batteries represent a possible grid-scale energy storage solution, having many advantages such as scalability, separation of power and energy capabilities, and simple operation. However, they can suffer from degradation during operation and the characteristics of the felt electrodes are little understood in terms of wetting, compression and pressure drops. Presented here is the design of a miniature flow cell that allows the use of x-ray computed tomography (CT) to study carbon felt materials in situ and operando, in both lab-based and synchrotron CT. Through application of the bespoke cell it is possible to observe felt fibres, electrolyte and pore phases and therefore enables non-destructive characterisation of an array of microstructural parameters during the operation of flow batteries. Furthermore, we expect this design can be readily adapted to the study of other electrochemical systems.

Alternative experiments using the geophysical fluid flow cell

NASA Technical Reports Server (NTRS)

Hart, J. E.

1984-01-01

This study addresses the possibility of doing large scale dynamics experiments using the Geophysical Fluid Flow Cell. In particular, cases where the forcing generates a statically stable stratification almost everywhere in the spherical shell are evaluated. This situation is typical of the Earth's atmosphere and oceans. By calculating the strongest meridional circulation expected in the spacelab experiments, and testing its stability using quasi-geostrophic stability theory, it is shown that strongly nonlinear baroclinic waves on a zonally symmetric modified thermal wind will not occur. The Geophysical Fluid Flow Cell does not have a deep enough fluid layer to permit useful studies of large scale planetary wave processes arising from instability. It is argued, however, that by introducing suitable meridional barriers, a significant contribution to the understanding of the oceanic thermocline problem could be made.

Cortical Flow-Driven Shapes of Nonadherent Cells.

PubMed

Callan-Jones, A C; Ruprecht, V; Wieser, S; Heisenberg, C P; Voituriez, R

2016-01-15

Nonadherent polarized cells have been observed to have a pearlike, elongated shape. Using a minimal model that describes the cell cortex as a thin layer of contractile active gel, we show that the anisotropy of active stresses, controlled by cortical viscosity and filament ordering, can account for this morphology. The predicted shapes can be determined from the flow pattern only; they prove to be independent of the mechanism at the origin of the cortical flow, and are only weakly sensitive to the cytoplasmic rheology. In the case of actin flows resulting from a contractile instability, we propose a phase diagram of three-dimensional cell shapes that encompasses nonpolarized spherical, elongated, as well as oblate shapes, all of which have been observed in experiment.

Automated flow cytometric analysis across large numbers of samples and cell types.

PubMed

Chen, Xiaoyi; Hasan, Milena; Libri, Valentina; Urrutia, Alejandra; Beitz, Benoît; Rouilly, Vincent; Duffy, Darragh; Patin, Étienne; Chalmond, Bernard; Rogge, Lars; Quintana-Murci, Lluis; Albert, Matthew L; Schwikowski, Benno

2015-04-01

Multi-parametric flow cytometry is a key technology for characterization of immune cell phenotypes. However, robust high-dimensional post-analytic strategies for automated data analysis in large numbers of donors are still lacking. Here, we report a computational pipeline, called FlowGM, which minimizes operator input, is insensitive to compensation settings, and can be adapted to different analytic panels. A Gaussian Mixture Model (GMM)-based approach was utilized for initial clustering, with the number of clusters determined using Bayesian Information Criterion. Meta-clustering in a reference donor permitted automated identification of 24 cell types across four panels. Cluster labels were integrated into FCS files, thus permitting comparisons to manual gating. Cell numbers and coefficient of variation (CV) were similar between FlowGM and conventional gating for lymphocyte populations, but notably FlowGM provided improved discrimination of "hard-to-gate" monocyte and dendritic cell (DC) subsets. FlowGM thus provides rapid high-dimensional analysis of cell phenotypes and is amenable to cohort studies. Copyright © 2015. Published by Elsevier Inc.

Modeling two-phase flow in PEM fuel cell channels

NASA Astrophysics Data System (ADS)

Wang, Yun; Basu, Suman; Wang, Chao-Yang

2008-05-01

This paper is concerned with the simultaneous flow of liquid water and gaseous reactants in mini-channels of a proton exchange membrane (PEM) fuel cell. Envisaging the mini-channels as structured and ordered porous media, we develop a continuum model of two-phase channel flow based on two-phase Darcy's law and the M2 formalism, which allow estimate of the parameters key to fuel cell operation such as overall pressure drop and liquid saturation profiles along the axial flow direction. Analytical solutions of liquid water saturation and species concentrations along the channel are derived to explore the dependences of these physical variables vital to cell performance on operating parameters such as flow stoichiometric ratio and relative humility. The two-phase channel model is further implemented for three-dimensional numerical simulations of two-phase, multi-component transport in a single fuel-cell channel. Three issues critical to optimizing channel design and mitigating channel flooding in PEM fuel cells are fully discussed: liquid water buildup towards the fuel cell outlet, saturation spike in the vicinity of flow cross-sectional heterogeneity, and two-phase pressure drop. Both the two-phase model and analytical solutions presented in this paper may be applicable to more general two-phase flow phenomena through mini- and micro-channels.

Refinement Of Hexahedral Cells In Euler Flow Computations

NASA Technical Reports Server (NTRS)

Melton, John E.; Cappuccio, Gelsomina; Thomas, Scott D.

1996-01-01

Topologically Independent Grid, Euler Refinement (TIGER) computer program solves Euler equations of three-dimensional, unsteady flow of inviscid, compressible fluid by numerical integration on unstructured hexahedral coordinate grid refined where necessary to resolve shocks and other details. Hexahedral cells subdivided, each into eight smaller cells, as needed to refine computational grid in regions of high flow gradients. Grid Interactive Refinement and Flow-Field Examination (GIRAFFE) computer program written in conjunction with TIGER program to display computed flow-field data and to assist researcher in verifying specified boundary conditions and refining grid.

Pressure-driven occlusive flow of a confined red blood cell.

PubMed

Savin, Thierry; Bandi, M M; Mahadevan, L

2016-01-14

When red blood cells (RBCs) move through narrow capillaries in the microcirculation, they deform as they flow. In pathophysiological processes such as sickle cell disease and malaria, RBC motion and flow are severely restricted. To understand this threshold of occlusion, we use a combination of experiment and theory to study the motion of a single swollen RBC through a narrow glass capillary of varying inner diameter. By tracking the movement of the squeezed cell as it is driven by a controlled pressure drop, we measure the RBC velocity as a function of the pressure gradient as well as the local capillary diameter, and find that the effective blood viscosity in this regime increases with both decreasing RBC velocity and tube radius by following a power-law that depends upon the length of the confined cell. Our observations are consistent with a simple elasto-hydrodynamic model and highlight the role of lateral confinement in the occluded pressure-driven slow flow of soft confined objects.

Progress Towards a Cartesian Cut-Cell Method for Viscous Compressible Flow

NASA Technical Reports Server (NTRS)

Berger, Marsha; Aftosmis, Michael J.

2012-01-01

We present preliminary development of an approach for simulating high Reynolds number steady compressible flow in two space dimensions using a Cartesian cut-cell finite volume method. We consider both laminar and turbulent flow with both low and high cell Reynolds numbers near the wall. The approach solves the full Navier-Stokes equations in all cells, and uses a wall model to address the resolution requirements near boundaries and to mitigate mesh irregularities in cut cells. We present a quadratic wall model for low cell Reynolds numbers. At high cell Reynolds numbers, the quadratic is replaced with a newly developed analytic wall model stemming from solution of a limiting form of the Spalart-Allmaras turbulence model which features a forward evaluation for flow velocity and exactly matches characteristics of the SA turbulence model in the field. We develop multigrid operators which attain convergence rates similar to inviscid multigrid. Investigations focus on preliminary verification and validation of the method. Flows over flat plates and compressible airfoils show good agreement with both theoretical results and experimental data. Mesh convergence studies on sub- and transonic airfoil flows show convergence of surface pressures with wall spacings as large as approx.0.1% chord. With the current analytic wall model, one or two additional refinements near the wall are required to obtain mesh converged values of skin friction.

Effect of Flow on Gene Regulation in Smooth Muscle Cells and Macromolecular Transport Across Endothelial Cell Monolayers

NASA Technical Reports Server (NTRS)

McIntire, Larry V.; Wagner, John E.; Papadaki, Maria; Whitson, Peggy A.; Eskin, Suzanne G.

1996-01-01

Endothelial cells line all of the vessels of the circulatory system, providing a non-thrombogenic conduit for blood flow; they regulate many complex functions in the vasculature, such as coagulation, fibrinolysis, platelet aggregation, vessel tone and growth, and leukocyte traffic; and they form the principal barrier to transport of substances between the blood and the surrounding tissue space. The permeability of endothelial cell changes with environmental stimuli; shear stress, in particular, applied either in vivo, or in vitro, induces changes in protein expression and secretion of vasoactive factors by endothelial cells. The ability to study the effects of shear on the macromolecular permeability of the cerebral vasculature is particularly important, since in no other place is the barrier function of the endothelium more important than in the brain. The endothelial cells of this organ have developed special barrier properties that keep the cerebral system from experiencing any drastic change in composition; together with glial cells, they form the blood brain barrier (BBB). We have studied the effect of flow on bovine BBB using flow chambers and tissue culture systems.

Interactions between cells and ionized dendritic biomaterials: Flow cytometry and fluorescence spectroscopic studies

NASA Astrophysics Data System (ADS)

Kannan, R. M.; Kolhe, Parag; Khandare, Jayant; Kannan, Sujatha; Lieh-Lai, Mary

2004-03-01

Dendrimers and hyperbranched polymers are a new class of macromolecules characterized by large density of "tunable" peripheral functional groups. Therefore dendrimers can serve as a model macromolecular system to study the influence of molecular geometry and charge density on transport across biological barriers, especially cellular interfaces. The effect of size, end-functionality, surface charge (pH), and the nature of the cell surface are expected to play an important role in transport, and are investigated using flow cytometry, fluorescene microscopy and UV/Vis spectroscopy. Our results suggest that at physiological pH, cationic polyamidoamine (PAMAM) dendrimers can enter the A549 cancer lung epithelial cells within 5 minutes, perhaps due to the favorable interaction between anionic surface receptors of cells and cationic PAMAM dendrimer, through adsorptive endocytosis. On the other hand, hyperbranched polyol, which is a neutral polymer at physiological pH, enters cells at a much slower rate. The entry of hyperbranched polyol may be because of fluid-phase pinocytosis. Our results also indicate that the dendritic polymers enter the cell surface much more rapidly than linear polymers, and some small drugs, suggesting that the high density of functional groups plays a key role in the interaction with the cell surface, and the subsequent transport inside.

Malignant human cell transformation of Marcellus shale gas drilling flow back water

PubMed Central

Yao, Yixin; Chen, Tingting; Shen, Steven S.; Niu, Yingmei; DesMarais, Thomas L; Linn, Reka; Saunders, Eric; Fan, Zhihua; Lioy, Paul; Kluz, Thomas; Chen, Lung-Chi; Wu, Zhuangchun; Costa, Max

2015-01-01

The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation is known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these waste waters, flow back water from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy / energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carried out to define the LC50 values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6 weeks with flow back waters produced colony formation in soft agar that was concentration dependant. In addition, flow back water-transformed BEAS-2B cells show a better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. PMID:26210350

Malignant human cell transformation of Marcellus Shale gas drilling flow back water.

PubMed

Yao, Yixin; Chen, Tingting; Shen, Steven S; Niu, Yingmei; DesMarais, Thomas L; Linn, Reka; Saunders, Eric; Fan, Zhihua; Lioy, Paul; Kluz, Thomas; Chen, Lung-Chi; Wu, Zhuangchun; Costa, Max; Zelikoff, Judith

2015-10-01

The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation are known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these wastewaters, flow back waters from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy/energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carried out to define the LC50 values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found to be elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6weeks with flow back waters produced colony formation in soft agar that was concentration dependent. In addition, flow back water-transformed BEAS-2B cells show better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. Copyright © 2015 Elsevier Inc. All rights reserved.

Buoyant miscible displacement flows in a nonuniform Hele-Shaw cell

NASA Astrophysics Data System (ADS)

Walling, E.; Mollaabbasi, R.; Taghavi, S. M.

2018-03-01

Miscible displacement flows within the gap of a nonuniform Hele-Shaw cell are considered, theoretically and experimentally. The cell is vertical and it can be diverging or converging. A light fluid displaces a heavy fluid downwards. The displacement imposed velocity is sufficiently large so that diffusive effects are negligible within our time scale of interest. For certain flow parameters, the displacement flow is characterized by a symmetric, two-dimensional penetration of the light fluid into the heavy one, for which a lubrication approximation approach is developed to simplify the governing equations and find a semianalytical solution for the flux functions. The solutions reveal how the cell nonuniformity may affect the propagation of the interface between the two fluids, versus the other flow parameters, i.e., the viscosity ratio (m ) and a buoyancy number (χ ), for which a detailed flow regime classification is presented. Our results demonstrate that the presence of nonuniformity adds a unique spatiotemporal nature to these displacements which is not the case for uniform cell flows. The combination of the model and experiments reveals the existence of self-spreading, spike, and unstable (viscous fingering) flow regimes, which may occur at various spatial positions within the cell. A converging cell may allow a transition from spike to self-spreading or unstable regime, whereas a diverging cell may offer a transition from self-spreading or unstable to spike regime. Our work demonstrates that the novel spatiotemporal nature of nonuniform cell flows must be considered through the numerical solution of the interface propagation equation, to yield accurate predictions about the flow behaviors at various spatial positions.

Full-angle tomographic phase microscopy of flowing quasi-spherical cells.

PubMed

Villone, Massimiliano M; Memmolo, Pasquale; Merola, Francesco; Mugnano, Martina; Miccio, Lisa; Maffettone, Pier Luca; Ferraro, Pietro

2017-12-19

We report a reliable full-angle tomographic phase microscopy (FA-TPM) method for flowing quasi-spherical cells along microfluidic channels. This method lies in a completely passive optical system, i.e. mechanical scanning or multi-direction probing of the sample is avoided. It exploits the engineered rolling of cells while they are flowing along a microfluidic channel. Here we demonstrate significant progress with respect to the state of the art of in-flow TPM by showing a general extension to cells having almost spherical shapes while they are flowing in suspension. In fact, the adopted strategy allows the accurate retrieval of rotation angles through a theoretical model of the cells' rotation in a dynamic microfluidic flow by matching it with phase-contrast images resulting from holographic reconstructions. So far, the proposed method is the first and the only one that permits to get in-flow TPM by probing the cells with full-angle, achieving accurate 3D refractive index mapping and the simplest optical setup, simultaneously. Proof of concept experiments were performed successfully on human breast adenocarcinoma MCF-7 cells, opening the way for the full characterization of circulating tumor cells (CTCs) in the new paradigm of liquid biopsy.

Adhesion behavior of endothelial progenitor cells to endothelial cells in simple shear flow

NASA Astrophysics Data System (ADS)

Gong, Xiao-Bo; Li, Yu-Qing; Gao, Quan-Chao; Cheng, Bin-Bin; Shen, Bao-Rong; Yan, Zhi-Qiang; Jiang, Zong-Lai

2011-12-01

The adhesion of endothelial progenitor cells (EPCs) on endothelial cells (ECs) is one of the critical physiological processes for the regenesis of vascular vessels and the prevention of serious cardiovascular diseases. Here, the rolling and adhesion behavior of EPCs on ECs was studied numerically. A two-dimensional numerical model was developed based on the immersed boundary method for simulating the rolling and adhesion of cells in a channel flow. The binding force arising from the catch bond of a receptor and ligand pair was modeled with stochastic Monte Carlo method and Hookean spring model. The effect of tumor necrosis factor alpha (TNF- α) on the expression of the number of adhesion molecules in ECs was analyzed experimentally. A flow chamber system with CCD camera was set up to observe the top view of the rolling of EPCs on the substrate cultivated with ECs. Numerical results prove that the adhesion of EPC on ECs is closely related to membrane stiffness of the cell and shear rate of the flow. It also suggests that the adhesion force between EPC and EC by P-selectin glycoprotein ligand-1 only is not strong enough to bond the cell onto vessel walls unless contributions of other catch bond are considered. Experimental results demonstrate that TNF- α enhanced the expressions of VCAM, ICAM, P-selectin and E-selectin in ECs, which supports the numerical results that the rolling velocity of EPC on TNF- α treated EC substrate decreases obviously compared with its velocity on the untreated one. It is found that because the adhesion is affected by both the rolling velocity and the deformability of the cell, an optimal stiffness of EPC may exist at a given shear rate of flow for achieving maximum adhesion rates.

Single-cell trapping and selective treatment via co-flow within a microfluidic platform.

PubMed

Benavente-Babace, A; Gallego-Pérez, D; Hansford, D J; Arana, S; Pérez-Lorenzo, E; Mujika, M

2014-11-15

Lab on a chip (LOC) systems provide interesting and low-cost solutions for key studies and applications in the biomedical field. Along with microfluidics, these microdevices make single-cell manipulation possible with high spatial and temporal resolution. In this work we have designed, fabricated and characterized a versatile and inexpensive microfluidic platform for on-chip selective single-cell trapping and treatment using laminar co-flow. The combination of co-existing laminar flow manipulation and hydrodynamic single-cell trapping for selective treatment offers a cost-effective solution for studying the effect of novel drugs on single-cells. The operation of the whole system is experimentally simple, highly adaptable and requires no specific equipment. As a proof of concept, a cytotoxicity study of ethanol in isolated hepatocytes is presented. The developed microfluidic platform controlled by means of co-flow is an attractive and multipurpose solution for the study of new substances of high interest in cell biology research. In addition, this platform will pave the way for the study of cell behavior under dynamic and controllable fluidic conditions providing information at the individual cell level. Thus, this analysis device could also hold a great potential to easily use the trapped cells as sensing elements expanding its functionalities as a cell-based biosensor with single-cell resolution. Copyright © 2014 Elsevier B.V. All rights reserved.

A Miniature Couette to Generate Shear for Flow Cytometry: Studying Real-Time Modulation of Intracellular Calcium in Monocytic Cells

PubMed Central

Zwartz, Gordon J.; Chigaev, Alexandre; Foutz, Terry D.; Edwards, Bruce; Sklar, Larry A.

2013-01-01

Extracellular hydrodynamic forces may be transmitted to the interior of cells through the alteration of integrin conformation and affinity. Integrin activation regulates leukocyte recruitment, cell activation, and transmigration. The cellular and molecular mechanisms for integrin activation are not precisely known, although intracellular calcium signaling is involved. Flow cytometry offers a versatile way to study intracellular calcium signaling in real-time. We report a novel method to generate defined shear by using a miniature Couette. Testing involved measuring shear induced intracellular calcium signals of human monoblastoid U937 cells in suspension. The Couette was connected externally to a flow cytometer and pressurized at 6 PSI (4.1 N/m2). Cells were subjected to well-defined shear between 0 and 1000 s−1 and delivered continuously within 10 s to a FACScan at 1 μl/s. Intracellular calcium levels and the percentage of cells activated increased as shear increased in duration and intensity. PMID:22045643

Fluid flow releases fibroblast growth factor-2 from human aortic smooth muscle cells

NASA Technical Reports Server (NTRS)

Rhoads, D. N.; Eskin, S. G.; McIntire, L. V.

2000-01-01

This study tested the hypothesis that fluid shear stress regulates the release of fibroblast growth factor (FGF)-2 from human aortic smooth muscle cells. FGF-2 is a potent mitogen that is involved in the response to vascular injury and is expressed in a wide variety of cell types. FGF-2 is found in the cytoplasm of cells and outside cells, where it associates with extracellular proteoglycans. To test the hypothesis that shear stress regulates FGF-2 release, cells were exposed to flow, and FGF-2 amounts were measured from the conditioned medium, pericellular fraction (extracted by heparin treatment), and cell lysate. Results from the present study show that after 15 minutes of shear stress at 25 dyne/cm(2) in a parallel-plate flow system, a small but significant fraction (17%) of the total FGF-2 was released from human aortic smooth muscle cells. FGF-2 levels in the circulating medium increased 10-fold over medium from static controls (P<0.01). A 50% increase in FGF-2 content versus control (P<0.01) was found in the pericellular fraction (extracted by heparin treatment). Furthermore, a significant decrease in FGF-2 was detected in the cell lysate, indicating that FGF-2 was released from inside the cell. Cell permeability studies with fluorescent dextran were performed to examine whether transient membrane disruption caused FGF-2 release. Flow cytometry detected a 50% increase in mean fluorescence of cells exposed to 25 dyne/cm(2) versus control cells. This indicates that the observed FGF-2 release from human aortic smooth muscle cells is likely due to transient membrane disruption on initiation of flow.

In Situ Spatiotemporal Mapping of Flow Fields around Seeded Stem Cells at the Subcellular Length Scale

PubMed Central

Song, Min Jae; Dean, David; Knothe Tate, Melissa L.

2010-01-01

A major hurdle to understanding and exploiting interactions between the stem cell and its environment is the lack of a tool for precise delivery of mechanical cues concomitant to observing sub-cellular adaptation of structure. These studies demonstrate the use of microscale particle image velocimetry (μ-PIV) for in situ spatiotemporal mapping of flow fields around mesenchymal stem cells, i.e. murine embryonic multipotent cell line C3H10T1/2, at the subcellular length scale, providing a tool for real time observation and analysis of stem cell adaptation to the prevailing mechanical milieu. In the absence of cells, computational fluid dynamics (CFD) predicts flow regimes within 12% of μ-PIV measures, achieving the technical specifications of the chamber and the flow rates necessary to deliver target shear stresses at a particular height from the base of the flow chamber. However, our μ-PIV studies show that the presence of cells per se as well as the density at which cells are seeded significantly influences local flow fields. Furthermore, for any given cell or cell seeding density, flow regimes vary significantly along the vertical profile of the cell. Hence, the mechanical milieu of the stem cell exposed to shape changing shear stresses, induced by fluid drag, varies with respect to proximity of surrounding cells as well as with respect to apical height. The current study addresses a previously unmet need to predict and observe both flow regimes as well as mechanoadaptation of cells in flow chambers designed to deliver precisely controlled mechanical signals to live cells. An understanding of interactions and adaptation in response to forces at the interface between the surface of the cell and its immediate local environment may be key for de novo engineering of functional tissues from stem cell templates as well as for unraveling the mechanisms underlying multiscale development, growth and adaptation of organisms. PMID:20862249

Go with the Flow: Cerebrospinal Fluid Flow Regulates Neural Stem Cell Proliferation.

PubMed

Kaneko, Naoko; Sawamoto, Kazunobu

2018-06-01

Adult neural stem cells in the wall of brain ventricles make direct contact with cerebrospinal fluid. In this issue of Cell Stem Cell, Petrik et al. (2018) demonstrate that these neural stem cells sense the flow of cerebrospinal fluid through a transmembrane sodium channel, ENaC, which regulates their proliferation. Copyright © 2018 Elsevier Inc. All rights reserved.

Pumping power considerations in the designs of NASA-Redox flow cells

NASA Technical Reports Server (NTRS)

Hoberecht, M. A.

1981-01-01

Pressure drop data for six different cell geometries of various flow port, manifold, and cavity dimensions are presented. The redox/energy/storage system uses two fully soluble redox couples as anode and cathode fluids. Both fluids are pumped through a redox cell, or stack of cells, where the electrochemical reactions take place at porous carbon felt electrodes. Pressure drop losses are therefore associated with this system due to the continuous flow of reactant solutions. The exact pressure drop within a redox flow cell is directly dependent on the flow rate as well as the various cell dimensions. Pumping power requirements for a specific set of cell operating conditions are found for various cell geometries once the flow rate and pressure drop are determined. These pumping power requirements contribute to the overall system parasitic energy losses which must be minimized, the choice of cell geometry becomes critical.

Overhead Projection Cell for Streamline Flow

ERIC Educational Resources Information Center

Waage, Harold M.

1969-01-01

Describes the construction and operation of an overhead projection apparatus designed to demonstrate streamline flow of a liquid. The apparatus consists of a Plexiglass tank containing water in which plates forming the cell are submerged, a constant level reservoir, an overflow device and a system for marking the flow lines with a dye. (LC)

Label-Free, Flow-Imaging Methods for Determination of Cell Concentration and Viability.

PubMed

Sediq, A S; Klem, R; Nejadnik, M R; Meij, P; Jiskoot, Wim

2018-05-30

To investigate the potential of two flow imaging microscopy (FIM) techniques (Micro-Flow Imaging (MFI) and FlowCAM) to determine total cell concentration and cell viability. B-lineage acute lymphoblastic leukemia (B-ALL) cells of 2 different donors were exposed to ambient conditions. Samples were taken at different days and measured with MFI, FlowCAM, hemocytometry and automated cell counting. Dead and live cells from a fresh B-ALL cell suspension were fractionated by flow cytometry in order to derive software filters based on morphological parameters of separate cell populations with MFI and FlowCAM. The filter sets were used to assess cell viability in the measured samples. All techniques gave fairly similar cell concentration values over the whole incubation period. MFI showed to be superior with respect to precision, whereas FlowCAM provided particle images with a higher resolution. Moreover, both FIM methods were able to provide similar results for cell viability as the conventional methods (hemocytometry and automated cell counting). FIM-based methods may be advantageous over conventional cell methods for determining total cell concentration and cell viability, as FIM measures much larger sample volumes, does not require labeling, is less laborious and provides images of individual cells.

Liquid chromatography/Fourier transform IR spectrometry interface flow cell

DOEpatents

Johnson, Charles C.; Taylor, Larry T.

1986-01-01

A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

Liquid chromatography/Fourier transform IR spectrometry interface flow cell

DOEpatents

Johnson, C.C.; Taylor, L.T.

1985-01-04

A zero dead volume (ZDV) microbore high performance liquid chromatography (..mu.. HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a ..mu.. HPLC column end fitting to minimize the transfer volume of the effluents exiting the ..mu.. HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF/sub 2/), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

Live-cell Imaging of Platelet Degranulation and Secretion Under Flow.

PubMed

Barendrecht, Arjan D; Verhoef, Johan J F; Pignatelli, Silvia; Pasterkamp, Gerard; Heijnen, Harry F G; Maas, Coen

2017-07-10

Blood platelets are essential players in hemostasis, the formation of thrombi to seal vascular breaches. They are also involved in thrombosis, the formation of thrombi that occlude the vasculature and injure organs, with life-threatening consequences. This motivates scientific research on platelet function and the development of methods to track cell-biological processes as they occur under flow conditions. A variety of flow models are available for the study of platelet adhesion and aggregation, two key phenomena in platelet biology. This work describes a method to study real-time platelet degranulation under flow during activation. The method makes use of a flow chamber coupled to a syringe-pump setup that is placed under a wide-field, inverted, LED-based fluorescence microscope. The setup described here allows for the simultaneous excitation of multiple fluorophores that are delivered by fluorescently labeled antibodies or fluorescent dyes. After live-cell imaging experiments, the cover glasses can be further processed and analyzed using static microscopy (i.e., confocal microscopy or scanning electron microscopy).

Numerical Simulation of Sickle Cell Blood Flow in the Microcirculation

NASA Astrophysics Data System (ADS)

Berger, Stanley A.; Carlson, Brian E.

2001-11-01

A numerical simulation of normal and sickle cell blood flow through the transverse arteriole-capillary microcirculation is carried out to model the dominant mechanisms involved in the onset of vascular stasis in sickle cell disease. The transverse arteriole-capillary network is described by Strahler's network branching method, and the oxygen and blood transport in the capillaries is modeled by a Krogh cylinder analysis utilizing Lighthill's lubrication theory, as developed by Berger and King. Poiseuille's law is used to represent blood flow in the arterioles. Applying this flow and transport model and utilizing volumetric flow continuity at each network bifurcation, a nonlinear system of equations is obtained, which is solved iteratively using a steepest descent algorithm coupled with a Newton solver. Ten different networks are generated and flow results are calculated for normal blood and sickle cell blood without and with precapillary oxygen loss. We find that total volumetric blood flow through the network is greater in the two sickle cell blood simulations than for normal blood owing to the anemia associated with sickle cell disease. The percentage of capillary blockage in the network increases dramatically with decreasing pressure drop across the network in the sickle cell cases while there is no blockage when normal blood flows through simulated networks. It is concluded that, in sickle cell disease, without any vasomotor dilation response to decreasing oxygen concentrations in the blood, capillary blockage will occur in the microvasculature even at average pressure drops across the transverse arteriole-capillary networks.

Identification of residual leukemic cells by flow cytometry in childhood B-cell precursor acute lymphoblastic leukemia: verification of leukemic state by flow-sorting and molecular/cytogenetic methods.

PubMed

Øbro, Nina F; Ryder, Lars P; Madsen, Hans O; Andersen, Mette K; Lausen, Birgitte; Hasle, Henrik; Schmiegelow, Kjeld; Marquart, Hanne V

2012-01-01

Reduction in minimal residual disease, measured by real-time quantitative PCR or flow cytometry, predicts prognosis in childhood B-cell precursor acute lymphoblastic leukemia. We explored whether cells reported as minimal residual disease by flow cytometry represent the malignant clone harboring clone-specific genomic markers (53 follow-up bone marrow samples from 28 children with B-cell precursor acute lymphoblastic leukemia). Cell populations (presumed leukemic and non-leukemic) were flow-sorted during standard flow cytometry-based minimal residual disease monitoring and explored by PCR and/or fluorescence in situ hybridization. We found good concordance between flow cytometry and genomic analyses in the individual flow-sorted leukemic (93% true positive) and normal (93% true negative) cell populations. Four cases with discrepant results had plausible explanations (e.g. partly informative immunophenotype and antigen modulation) that highlight important methodological pitfalls. These findings demonstrate that with sufficient experience, flow cytometry is reliable for minimal residual disease monitoring in B-cell precursor acute lymphoblastic leukemia, although rare cases require supplementary PCR-based monitoring.

Applications of flow cytometry to toxicological mycotoxin effects in cultured mammalian cells: a review.

PubMed

Juan-García, Ana; Manyes, Lara; Ruiz, María-José; Font, Guillermina

2013-06-01

This review gives an overview of flow cytometry applications to toxicological studies of several physiological target sites of mycotoxins on different mammalian cell lines. Mycotoxins are secondary metabolites of fungi that may be present in food, feed, air and water. The increasing presence of mycotoxins in crops, their wide distribution in the food chain, and their potential for toxicity demonstrate the need for further knowledge. Flow cytometry has become a valuable tool in mycotoxin studies in recent years for the rapid analysis of single cells in a mixture. In toxicology, the power of these methods lies in the possibility of determining a wide range of cell parameters, providing valuable information to elucidate cell growth and viability, metabolic activity, mitochondrial membrane potential and membrane integrity mechanisms. There are studies using flow cytometry technique on Alternaria, Aspergillus, Fusarium and Penicillium mycotoxins including information about cell type, assay conditions and functional parameters. Most of the studies collected in the literature are on deoxynivalenol and zearalenone mycotoxins. Cell cycle analysis and apoptosis are the processes more widely investigated. Copyright © 2013 Elsevier Ltd. All rights reserved.

Flow cytometry and cell sorting of heterogeneous microbial populations: the importance of single-cell analyses.

PubMed Central

Davey, H M; Kell, D B

1996-01-01

The most fundamental questions such as whether a cell is alive, in the sense of being able to divide or to form a colony, may sometimes be very hard to answer, since even axenic microbial cultures are extremely heterogeneous. Analyses that seek to correlate such things as viability, which is a property of an individual cell, with macroscopic measurements of culture variables such as ATP content, respiratory activity, and so on, must inevitably fail. It is therefore necessary to make physiological measurements on individual cells. Flow cytometry is such a technique, which allows one to analyze cells rapidly and individually and permits the quantitative analysis of microbial heterogeneity. It therefore offers many advantages over conventional measurements for both routine and more exploratory analyses of microbial properties. While the technique has been widely applied to the study of mammalian cells, is use in microbiology has until recently been much more limited, largely because of the smaller size of microbes and the consequently smaller optical signals obtainable from them. Since these technical barriers no longer hold, flow cytometry with appropriate stains has been used for the rapid discrimination and identification of microbial cells, for the rapid assessment of viability and of the heterogeneous distributions of a wealth of other more detailed physiological properties, for the analysis of antimicrobial drug-cell interactions, and for the isolation of high-yielding strains of biotechnological interest. Flow cytometric analyses provide an abundance of multivariate data, and special methods have been devised to exploit these. Ongoing advances mean that modern flow cytometers may now be used by nonspecialists to effect a renaissance in our understanding of microbial heterogeneity. PMID:8987359

3D-printed and CNC milled flow-cells for chemiluminescence detection.

PubMed

Spilstead, Kara B; Learey, Jessica J; Doeven, Egan H; Barbante, Gregory J; Mohr, Stephan; Barnett, Neil W; Terry, Jessica M; Hall, Robynne M; Francis, Paul S

2014-08-01

Herein we explore modern fabrication techniques for the development of chemiluminescence detection flow-cells with features not attainable using the traditional coiled tubing approach. This includes the first 3D-printed chemiluminescence flow-cells, and a milled flow-cell designed to split the analyte stream into two separate detection zones within the same polymer chip. The flow-cells are compared to conventional detection systems using flow injection analysis (FIA) and high performance liquid chromatography (HPLC), with the fast chemiluminescence reactions of an acidic potassium permanganate reagent with morphine and a series of adrenergic phenolic amines. Copyright © 2014 Elsevier B.V. All rights reserved.

The dynamic behavior of chemically "stiffened" red blood cells in microchannel flows.

PubMed

Forsyth, Alison M; Wan, Jiandi; Ristenpart, William D; Stone, Howard A

2010-07-01

The rigidity of red blood cells (RBCs) plays an important role in whole blood viscosity and is correlated with several cardiovascular diseases. Two chemical agents that are commonly used to study cell deformation are diamide and glutaraldehyde. Despite diamide's common usage, there are discrepancies in the literature surrounding diamide's effect on the deformation of RBCs in shear and pressure-driven flows; in particular, shear flow experiments have shown that diamide stiffens cells, while pressure-driven flow in capillaries did not give this result. We performed pressure-driven flow experiments with RBCs in a microfluidic constriction and quantified the cell dynamics using high-speed imaging. Diamide, which affects RBCs by cross-linking spectrin skeletal membrane proteins, did not reduce deformation and showed an unchanged effective strain rate when compared to healthy cells. In contrast, glutaraldehyde, which is a non-specific fixative that acts on all components of the cell, did reduce deformation and showed increased instances of tumbling, both of which are characteristic features of stiffened, or rigidified, cells. Because glutaraldehyde increases the effective viscosity of the cytoplasm and lipid membrane while diamide does not, one possible explanation for our results is that viscous effects in the cytoplasm and/or lipid membrane are a dominant factor in dictating dynamic responses of RBCs in pressure-driven flows. Finally, literature on the use of diamide as a stiffening agent is summarized, and provides supporting evidence for our conclusions. Copyright 2010 Elsevier Inc. All rights reserved.

Modeling two-phase flow in three-dimensional complex flow-fields of proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Kim, Jinyong; Luo, Gang; Wang, Chao-Yang

2017-10-01

3D fine-mesh flow-fields recently developed by Toyota Mirai improved water management and mass transport in proton exchange membrane (PEM) fuel cell stacks, suggesting their potential value for robust and high-power PEM fuel cell stack performance. In such complex flow-fields, Forchheimer's inertial effect is dominant at high current density. In this work, a two-phase flow model of 3D complex flow-fields of PEMFCs is developed by accounting for Forchheimer's inertial effect, for the first time, to elucidate the underlying mechanism of liquid water behavior and mass transport inside 3D complex flow-fields and their adjacent gas diffusion layers (GDL). It is found that Forchheimer's inertial effect enhances liquid water removal from flow-fields and adds additional flow resistance around baffles, which improves interfacial liquid water and mass transport. As a result, substantial improvements in high current density cell performance and operational stability are expected in PEMFCs with 3D complex flow-fields, compared to PEMFCs with conventional flow-fields. Higher current density operation required to further reduce PEMFC stack cost per kW in the future will necessitate optimizing complex flow-field designs using the present model, in order to efficiently remove a large amount of product water and hence minimize the mass transport voltage loss.

A multi-component parallel-plate flow chamber system for studying the effect of exercise-induced wall shear stress on endothelial cells.

PubMed

Wang, Yan-Xia; Xiang, Cheng; Liu, Bo; Zhu, Yong; Luan, Yong; Liu, Shu-Tian; Qin, Kai-Rong

2016-12-28

In vivo studies have demonstrated that reasonable exercise training can improve endothelial function. To confirm the key role of wall shear stress induced by exercise on endothelial cells, and to understand how wall shear stress affects the structure and the function of endothelial cells, it is crucial to design and fabricate an in vitro multi-component parallel-plate flow chamber system which can closely replicate exercise-induced wall shear stress waveforms in artery. The in vivo wall shear stress waveforms from the common carotid artery of a healthy volunteer in resting and immediately after 30 min acute aerobic cycling exercise were first calculated by measuring the inner diameter and the center-line blood flow velocity with a color Doppler ultrasound. According to the above in vivo wall shear stress waveforms, we designed and fabricated a parallel-plate flow chamber system with appropriate components based on a lumped parameter hemodynamics model. To validate the feasibility of this system, human umbilical vein endothelial cells (HUVECs) line were cultured within the parallel-plate flow chamber under abovementioned two types of wall shear stress waveforms and the intracellular actin microfilaments and nitric oxide (NO) production level were evaluated using fluorescence microscope. Our results show that the trends of resting and exercise-induced wall shear stress waveforms, especially the maximal, minimal and mean wall shear stress as well as oscillatory shear index, generated by the parallel-plate flow chamber system are similar to those acquired from the common carotid artery. In addition, the cellular experiments demonstrate that the actin microfilaments and the production of NO within cells exposed to the two different wall shear stress waveforms exhibit different dynamic behaviors; there are larger numbers of actin microfilaments and higher level NO in cells exposed in exercise-induced wall shear stress condition than resting wall shear stress condition

Experimental study of the flow pattern around a bubble confined in a microfluidic Hele-Shaw cell

NASA Astrophysics Data System (ADS)

Tsoumpas, Yannis; Fajolles, Christophe; Malloggi, Florent

2017-11-01

The flow field around a bubble moving with respect to a surrounding liquid in a Hele-Shaw cell can usually be characterized by a recirculating flow, which is typically attributed to a Marangoni effect due to surface tension gradients generated by a non-uniform distribution of surfactants (or temperature) along the liquid-gas interface. In the present study, we try to visualize such a flow employing 3D micro-particle tracking velocimetry. We perform experiments on an immobile flattened air bubble that is surrounded by a flow of aqueous solution of surfactant (SDS), in a microfluidic chamber described in the work of Sungyon Lee et al.. The suspending fluid is seeded with spherical micro-particles, with those captured by the recirculating flow orbiting in a three-dimensional trajectory in the vicinity of the liquid-air interface. We address the effect of velocity of the surrounding fluid, surfactant concentration and bubble radius on the recirculating flow pattern. The case of a liquid-liquid interface, with a hexadecane drop as the dispersed phase, is also discussed. The authors would like to acknowledge the financial support of Enhanced Eurotalents program (an FP7 Marie Skłodowska-Curie COFUND program) & ANR (ANR-13-BS09-0011).

Ferroptosis and Cell Death Analysis by Flow Cytometry.

PubMed

Chen, Daishi; Eyupoglu, Ilker Y; Savaskan, Nicolai

2017-01-01

Cell death and its recently discovered regulated form ferroptosis are characterized by distinct morphological, electrophysiological, and pharmacological features. In particular ferroptosis can be induced by experimental compounds and clinical drugs (i.e., erastin, sulfasalazine, sorafenib, and artesunate) in various cell types and cancer cells. Pharmacologically, this cell death process can be inhibited by iron chelators and lipid peroxidation inhibitors. Relevance of this specific cell death form has been found in different pathological conditions such as cancer, neurotoxicity, neurodegeneration, and ischemia. Distinguishing cell viability and cell death is essential for experimental and clinical applications and a key component in flow cytometry experiments. Dead cells can compromise the integrity of the data by nonspecific binding of antibodies and dyes. Therefore it is essential that dead cells are robustly and reproducibly identified and characterized by means of cytometry application. Here we describe a procedure to detect and quantify cell death and its specific form ferroptosis based on standard flow cytometry techniques.

Long waves in parallel flow in Hele-Shaw cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeybek, M.; Yortsos, Y.C.

1991-09-09

The evolution of fluid interfaces in parallel flow in Hele-Shaw cells is studied theoretically and experimentally in the limit of large capillary number. It is shown that such interfaces support wave motion, the amplitude of which for long waves is governed by a set of Korteweg--de Vries and Airy equations. Experiments conducted in a long Hele-Shaw cell validate the theory in the symmetric case.

Chaos in an Eulerian Based Model of Sickle Cell Blood Flow

NASA Astrophysics Data System (ADS)

Apori, Akwasi; Harris, Wesley

2001-11-01

A novel Eulerian model describing the manifestation of sickle cell blood flow in the capillaries has been formulated to study the apparently chaotic onset of sickle cell crises. This Eulerian model was based on extending previous models of sickle cell blood flow which were limited due to their Lagrangian formulation. Oxygen concentration, red blood cell velocity, cell stiffness, and plasma viscosity were modeled as system state variables. The governing equations of the system were expressed in canonical form. The non-linear coupling of velocity-viscosity and viscosity- stiffness proved to be the origin of chaos in the system. The system was solved with respect to a control parameter representing the unique rheology of the sickle cell erythrocytes. Results of chaos tests proved positive for various ranges of the control parameter. The results included con-tinuous patterns found in the Poincare section, spectral broadening of the Fourier power spectrum, and positive Lyapunov exponent values. The onset of chaos predicted by this sickle cell flow model as the control parameter was varied appeared to coincide with the change from a healthy state to a crisis state in a sickle cell patient. This finding that sickle cell crises may be caused from the well understood change of a solution from a steady state to chaotic could point to new ways in preventing and treating crises and should be validated in clinical trials.

Redox flow cell energy storage systems

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1979-01-01

The redox flow cell energy storage system being developed by NASA for use in remote power systems and distributed storage installations for electric utilities is presented. The system under consideration is an electrochemical storage device which utilizes the oxidation and reduction of two fully soluble redox couples (acidified chloride solutions of chromium and iron) as active electrode materials separated by a highly selective ion exchange membrane. The reactants are contained in large storage tanks and pumped through a stack of redox flow cells where the electrochemical reactions take place at porous carbon felt electrodes. Redox equipment has allowed the incorporation of state of charge readout, stack voltage control and system capacity maintenance (rebalance) devices to regulate cells in a stack jointly. A 200 W, 12 V system with a capacity of about 400 Wh has been constructed, and a 2 kW, 10kWh system is planned.

Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

PubMed Central

Chen, Jian; Xue, Chengcheng; Zhao, Yang; Chen, Deyong; Wu, Min-Hsien; Wang, Junbo

2015-01-01

This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications. PMID:25938973

Flow Cells for Scalable Energy Conversion and Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mukundan, Rangachary

2017-10-26

This project is a response to current flow systems that are V-aqueous and not cost effective. It will hopefully enable high energy/ power density flow cells through rational materials and system design.

Upward swimming of a sperm cell in shear flow.

PubMed

Omori, Toshihiro; Ishikawa, Takuji

2016-03-01

Mammalian sperm cells are required to swim over long distances, typically around 1000-fold their own length. They must orient themselves and maintain a swimming motion to reach the ovum, or egg cell. Although the mechanism of long-distance navigation is still unclear, one possible mechanism, rheotaxis, was reported recently. This work investigates the mechanism of the rheotaxis in detail by simulating the motions of a sperm cell in shear flow adjacent to a flat surface. A phase diagram was developed to show the sperm's swimming motion under different shear rates, and for varying flagellum waveform conditions. The results showed that, under shear flow, the sperm is able to hydrodynamically change its swimming direction, allowing it to swim upwards against the flow, which suggests that the upward swimming of sperm cells can be explained using fluid mechanics, and this can then be used to further understand physiology of sperm cell navigation.

Combustor air flow control method for fuel cell apparatus

DOEpatents

Clingerman, Bruce J.; Mowery, Kenneth D.; Ripley, Eugene V.

2001-01-01

A method for controlling the heat output of a combustor in a fuel cell apparatus to a fuel processor where the combustor has dual air inlet streams including atmospheric air and fuel cell cathode effluent containing oxygen depleted air. In all operating modes, an enthalpy balance is provided by regulating the quantity of the air flow stream to the combustor to support fuel cell processor heat requirements. A control provides a quick fast forward change in an air valve orifice cross section in response to a calculated predetermined air flow, the molar constituents of the air stream to the combustor, the pressure drop across the air valve, and a look up table of the orifice cross sectional area and valve steps. A feedback loop fine tunes any error between the measured air flow to the combustor and the predetermined air flow.

Detection and capture of breast cancer cells with photoacoustic flow cytometry

NASA Astrophysics Data System (ADS)

Bhattacharyya, Kiran; Goldschmidt, Benjamin S.; Viator, John A.

2016-08-01

According to the Centers for Disease Control and Prevention, breast cancer is the most common cancer and the second leading cause of cancer related deaths among women. Metastasis-the presence of secondary tumors caused by the spread of cancer cells via the circulatory or lymphatic systems-significantly worsens the prognosis of any breast cancer patient. A technique is developed to detect circulating breast cancer cells in human blood using a photoacoustic flow cytometry method. A Q-switched laser is used to interrogate thousands of blood cells with one pulse as they flow through the beam path. Cells that are optically absorbing, either naturally or artificially, emit an ultrasound wave as a result of the photoacoustic (PA) effect. Breast cancer cells are targeted with chromophores through immunochemistry in order to enhance optical absorption. After which, the PA cytometry device is calibrated to demonstrate the ability to detect single cells. Cultured breast cancer cells are added to whole blood to reach a biologically relevant concentration of about 25 to 45 breast cancer cells per 1 mL of blood. An in vitro PA flow cytometer is used to detect and isolate these cells followed by capture with the use of a micromanipulator. This method can not only be used to determine the disease state of the patient and the response to therapy but also it can be used for genetic testing and in vitro drug trials since the circulating cell can be captured and studied.

Optical tweezers for measuring the interaction of the two single red blood cells in flow condition

NASA Astrophysics Data System (ADS)

Lee, Kisung; Muravyov, Alexei; Semenov, Alexei; Wagner, Christian; Priezzhev, Alexander

2017-03-01

Aggregation of red blood cells (RBCs) is an intrinsic property of blood, which has direct effect on the blood viscosity and therefore affects overall the blood circulation throughout the body. It is attracting interest for the research in both fundamental science and clinical application. Despite of the intensive research, the aggregation mechanism is remaining not fully clear. Recent advances in methods allowed measuring the interaction between single RBCs in a well-defined configuration leading the better understanding of the mechanism of the process. However the most of the studies were made on the static cells. Thus, the measurements in flow mimicking conditions are missing. In this work, we aim to study the interaction of two RBCs in the flow conditions. We demonstrate the characterization of the cells interaction strength (or flow tolerance) by measuring the flow velocity to be applied to separate two aggregated cells trapped by double channel optical tweezers in a desired configuration. The age-separated cells were used for this study. The obtained values for the minimum flow velocities needed to separate the two cells were found to be 78.9 +/- 6.1 μm/s and 110 +/- 13 μm/s for old and young cells respectively. The data obtained is in agreement with the observations reported by other authors. The significance of our results is in ability for obtaining a comprehensible and absolute physical value characterizing the cells interaction in flow conditions (not like the Aggregation Index measured in whole blood suspensions by other techniques, which is some abstract parameter)

Improvement and analysis of the hydrogen-cerium redox flow cell

NASA Astrophysics Data System (ADS)

Tucker, Michael C.; Weiss, Alexandra; Weber, Adam Z.

2016-09-01

The H2-Ce redox flow cell is optimized using commercially-available cell materials. Cell performance is found to be sensitive to the upper charge cutoff voltage, membrane boiling pretreatment, methanesulfonic-acid concentration, (+) electrode surface area and flow pattern, and operating temperature. Performance is relatively insensitive to membrane thickness, Cerium concentration, and all features of the (-) electrode including hydrogen flow. Cell performance appears to be limited by mass transport and kinetics in the cerium (+) electrode. Maximum discharge power of 895 mW cm-2 was observed at 60 °C; an energy efficiency of 90% was achieved at 50 °C. The H2-Ce cell is promising for energy storage assuming one can optimize Ce reaction kinetics and electrolyte.

The Removal of Human Breast Cancer Cells from Hematopoietic CD34+ Stem Cells by Dielectrophoretic Field-Flow-Fractionation

PubMed Central

HUANG, YING; YANG, JUN; WANG, XIAO-BO; BECKER, FREDERICK F.; GASCOYNE, PETER R.C.

2009-01-01

Dielectrophoretic field-flow-fractionation (DEP-FFF) was used to purge human breast cancer MDA-435 cells from hematopoietic CD34+ stem cells. An array of interdigitated microelectrodes lining the bottom surface of a thin chamber was used to generate dielectrophoretic forces that levitated the cell mixture in a fluid flow profile. CD34+ stem cells were levitated higher, were carried faster by the fluid flow, and exited the separation chamber earlier than the cancer cells. Using on-line flow cytometry, efficient separation of the cell mixture was observed in less than 12 min, and CD34+ stem cell fractions with a purity >99.2% were obtained. The method of DEP-FFF is potentially applicable to many biomedical cell separation problems, including microfluidic-scale diagnosis and preparative-scale purification of cell subpopulations. PMID:10791899

A novel flow-perfusion bioreactor supports 3D dynamic cell culture.

PubMed

Sailon, Alexander M; Allori, Alexander C; Davidson, Edward H; Reformat, Derek D; Allen, Robert J; Warren, Stephen M

2009-01-01

Bone engineering requires thicker three-dimensional constructs than the maximum thickness supported by standard cell-culture techniques (2 mm). A flow-perfusion bioreactor was developed to provide chemotransportation to thick (6 mm) scaffolds. Polyurethane scaffolds, seeded with murine preosteoblasts, were loaded into a novel bioreactor. Control scaffolds remained in static culture. Samples were harvested at days 2, 4, 6, and 8 and analyzed for cellular distribution, viability, metabolic activity, and density at the periphery and core. By day 8, static scaffolds had a periphery cell density of 67% +/- 5.0%, while in the core it was 0.3% +/- 0.3%. Flow-perfused scaffolds demonstrated peripheral cell density of 94% +/- 8.3% and core density of 76% +/- 3.1% at day 8. Flow perfusion provides chemotransportation to thick scaffolds. This system may permit high throughput study of 3D tissues in vitro and enable prefabrication of biological constructs large enough to solve clinical problems.

A Novel Counter Sheet-flow Sandwich Cell Culture Device for Mammalian Cell Growth in Space

NASA Astrophysics Data System (ADS)

Sun, Shujin; Gao, Yuxin; Shu, Nanjiang; Tang, Zemei; Tao, Zulai; Long, Mian

2008-08-01

Cell culture and growth in space is crucial to understand the cellular responses under microgravity. The effects of microgravity were coupled with such environment restrictions as medium perfusion, in which the underlying mechanism has been poorly understood. In the present work, a customer-made counter sheet-flow sandwich cell culture device was developed upon a biomechanical concept from fish gill breathing. The sandwich culture unit consists of two side chambers where the medium flow is counter-directional, a central chamber where the cells are cultured, and two porous polycarbonate membranes between side and central chambers. Flow dynamics analysis revealed the symmetrical velocity profile and uniform low shear rate distribution of flowing medium inside the central culture chamber, which promotes sufficient mass transport and nutrient supply for mammalian cell growth. An on-orbit experiment performed on a recovery satellite was used to validate the availability of the device.

Electrochemical Oscillations of Nickel Electrodissolution in an Epoxy-Based Microchip Flow Cell

PubMed Central

Cioffi, Alexander G.; Martin, R. Scott; Kiss, István Z.

2011-01-01

We investigate the nonlinear dynamics of transpassive electrodissolution of nickel in sulfuric acid in an epoxy-based microchip flow cell. We observed bistability, smooth, relaxation, and period-2 waveform current oscillations with external resistance attached to the electrode in the microfabricated electrochemical cell with 0.05 mm diameter Ni wire under potentiostatic control. Experiments with 1mm × 0.1 mm Ni electrode show spontaneous oscillations without attached external resistance; similar surface area electrode in macrocell does not exhibit spontaneous oscillations. Combined experimental and numerical studies show that spontaneous oscillation with the on-chip fabricated electrochemical cell occurs because of the unusually large ohmic potential drop due to the constrained current in the narrow flow channel. This large IR potential drop is expected to have an important role in destabilizing negative differential resistance electrochemical (e.g., metal dissolution and electrocatalytic) systems in on-chip integrated microfludic flow cells. The proposed experimental setup can be extendend to multi-electrode configurations; the epoxy-based substrate procedure thus holds promise in electroanalytical applications that require collector-generator multi-electrodes wires with various electrode sizes, compositions, and spacings as well as controlled flow conditions. PMID:21822407

Electrochemical Oscillations of Nickel Electrodissolution in an Epoxy-Based Microchip Flow Cell.

PubMed

Cioffi, Alexander G; Martin, R Scott; Kiss, István Z

2011-08-01

We investigate the nonlinear dynamics of transpassive electrodissolution of nickel in sulfuric acid in an epoxy-based microchip flow cell. We observed bistability, smooth, relaxation, and period-2 waveform current oscillations with external resistance attached to the electrode in the microfabricated electrochemical cell with 0.05 mm diameter Ni wire under potentiostatic control. Experiments with 1mm × 0.1 mm Ni electrode show spontaneous oscillations without attached external resistance; similar surface area electrode in macrocell does not exhibit spontaneous oscillations. Combined experimental and numerical studies show that spontaneous oscillation with the on-chip fabricated electrochemical cell occurs because of the unusually large ohmic potential drop due to the constrained current in the narrow flow channel. This large IR potential drop is expected to have an important role in destabilizing negative differential resistance electrochemical (e.g., metal dissolution and electrocatalytic) systems in on-chip integrated microfludic flow cells. The proposed experimental setup can be extendend to multi-electrode configurations; the epoxy-based substrate procedure thus holds promise in electroanalytical applications that require collector-generator multi-electrodes wires with various electrode sizes, compositions, and spacings as well as controlled flow conditions.

Improvement and analysis of the hydrogen-cerium redox flow cell

DOE PAGES

Tucker, Michael C.; Weiss, Alexandra; Weber, Adam Z.

2016-08-03

In this paper, the H 2-Ce redox flow cell is optimized using commercially-available cell materials. Cell performance is found to be sensitive to the upper charge cutoff voltage, membrane boiling pretreatment, methanesulfonic-acid concentration, (+) electrode surface area and flow pattern, and operating temperature. Performance is relatively insensitive to membrane thickness, Cerium concentration, and all features of the (-) electrode including hydrogen flow. Cell performance appears to be limited by mass transport and kinetics in the cerium (+) electrode. Maximum discharge power of 895 mW cm -2 was observed at 60 °C; an energy efficiency of 90% was achieved at 50more » °C. Finally, the H 2-Ce cell is promising for energy storage assuming one can optimize Ce reaction kinetics and electrolyte.« less

Cross-flow electrochemical reactor cells, cross-flow reactors, and use of cross-flow reactors for oxidation reactions

DOEpatents

Balachandran, Uthamalingam; Poeppel, Roger B.; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Udovich, Carl A.

1994-01-01

This invention discloses cross-flow electrochemical reactor cells containing oxygen permeable materials which have both electron conductivity and oxygen ion conductivity, cross-flow reactors, and electrochemical processes using cross-flow reactor cells having oxygen permeable monolithic cores to control and facilitate transport of oxygen from an oxygen-containing gas stream to oxidation reactions of organic compounds in another gas stream. These cross-flow electrochemical reactors comprise a hollow ceramic blade positioned across a gas stream flow or a stack of crossed hollow ceramic blades containing a channel or channels for flow of gas streams. Each channel has at least one channel wall disposed between a channel and a portion of an outer surface of the ceramic blade, or a common wall with adjacent blades in a stack comprising a gas-impervious mixed metal oxide material of a perovskite structure having electron conductivity and oxygen ion conductivity. The invention includes reactors comprising first and second zones seprated by gas-impervious mixed metal oxide material material having electron conductivity and oxygen ion conductivity. Prefered gas-impervious materials comprise at least one mixed metal oxide having a perovskite structure or perovskite-like structure. The invention includes, also, oxidation processes controlled by using these electrochemical reactors, and these reactions do not require an external source of electrical potential or any external electric circuit for oxidation to proceed.

Detection, isolation, and capture of circulating breast cancer cells with photoacoustic flow cytometry

NASA Astrophysics Data System (ADS)

Bhattacharyya, Kiran; Njoroge, Martin; Goldschmidt, Benjamin S.; Gaffigan, Brian; Rood, Kyle; Viator, John A.

2013-03-01

According to the CDC, breast cancer is the most common cancer and the second leading cause of cancer related deaths among women. Metastasis, or the presence of secondary tumors caused by the spread of cancer cells via the circulatory or lymphatic systems, significantly worsens the prognosis of any breast cancer patient. In this study, a technique is developed to detect circulating breast cancer cells in human blood using a photoacoustic flow cytometry method. A Q-switched laser with a 5 ns pulse at 532 nm is used to interrogate thousands of cells with one pulse as they flow through the beam path. Cells which are pigmented, either naturally or artificially, emit an ultrasound wave as a result of the photoacoustic (PA) effect. Breast cancer cells are targeted with chromophores through immunochemistry in order to provide pigment. After which, the device is calibrated to demonstrate a single-cell detection limit. Cultured breast cancer cells are added to whole blood to reach a biologically relevant concentration of about 25-45 breast cancer cells per 1 mL of blood. An in vitro photoacoustic flow cytometer is used to detect and isolate these cells followed by capture with the use of a micromanipulator. This method can not only be used to determine the disease state of the patient and the response to therapy, it can also be used for genetic testing and in vitro drug trials since the circulating cell can be captured and studied.

Solution-Adaptive Cartesian Cell Approach for Viscous and Inviscid Flows

NASA Technical Reports Server (NTRS)

Coirier, William J.; Powell, Kenneth G.

1996-01-01

A Cartesian cell-based approach for adaptively refined solutions of the Euler and Navier-Stokes equations in two dimensions is presented. Grids about geometrically complicated bodies are generated automatically, by the recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, polygonal cut cells are created using modified polygon-clipping algorithms. The grid is stored in a binary tree data structure that provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive mesh refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite volume formulation. The convective terms are upwinded: A linear reconstruction of the primitive variables is performed, providing input states to an approximate Riemann solver for computing the fluxes between neighboring cells. The results of a study comparing the accuracy and positivity of two classes of cell-centered, viscous gradient reconstruction procedures is briefly summarized. Adaptively refined solutions of the Navier-Stokes equations are shown using the more robust of these gradient reconstruction procedures, where the results computed by the Cartesian approach are compared to theory, experiment, and other accepted computational results for a series of low and moderate Reynolds number flows.

Cell-production rates estimated by the use of vincristine sulphate and flow cytometry. I. An in vitro study using murine tumour cell lines.

PubMed

Barfod, I H; Barfod, N M

1980-01-01

A method for the evaluation of cell-production rates is described which combines flow cytometry (FCM) and the stathmokinetic method. By means of FCM it is possible to estimate the distribution of cells with G1, S and (G2 + M) DNA content in a population. As this method gives the relative (G2 + M) DNA content of cells within the cell cycle, it may be possible to evaluate cell-production rates by this technique. In the present study it was found that administration of a metaphase-arresting (stathmokinetic) agent, vincristine sulphate (VS), to asynchronous cell populations of three different murine tumour cell lines in vitro increased the peak representing cells with (G2 + M) DNA content as the number of mitotic (M) cells increased during the period of treatment. The accumulation of mitotic cells was determined by cell counts on smears under the microscope and compared with increase in the (G2 + M) DNA peak measured by FCM as a function of time after the administration of VS. Good agreement was obtained between the cell-production rates as estimated by FCM and by mitotic counts in all three cell lines investigated.

Detection of early changes in lung cell cytology by flow-systems analysis techniques. [Rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steinkamp, J.A.; Wilson, J.S.; Svitra, Z.V.

1980-03-01

Ongoing experiments designed to develop automated flow-analysis methods for assaying damage to pulmonary lavage cells in experimental animals exposed by inhalation to environmental pollutants are summarized. Pulmonary macrophages were characterized on their ability to phagocytize polystyrene latex fluorescent spheres. Lung cells consisting primarily of macrophages and leukocytes were analyzed for fluorescence (phagocytosis of spheres) and size using flow cytometric methods. Studies also concentrated on combining phagocytosis with other cellular parameters (DNA content, cell viability, and B-glucuronidase activity). As baseline studies are completed in normal animals, experimental animals will be exposed to gaseous and particulate environmental pollutants. (ERB

Dynamics of model blood cells in shear flow

NASA Astrophysics Data System (ADS)

Podgorski, Thomas; Callens, Natacha; Minetti, Christophe; Coupier, Gwennou; Dubois, Frank; Misbah, Chaouqi

The dynamics of a vesicle suspension in shear flow was investigated by digital holographic microscopy [1] in parabolic flights and in the MASER 11 sounding rocket. Vesicles are lipid membranes which mimic the mechanical behaviour of cells, such as red blood cells in flow. In a simple shear flow between parallel walls, a lift force of purely viscous origin pushes vesicles away from walls. Our parabolic flight experiments [2] reveal that the lift velocity in a dilute suspen-sion is well described by theoretical predictions by Olla. As vesicles gather near the center of the flow chamber due to lift forces from both walls, one expects hydrodynamic interactions of pairs of vesicles to result in shear induced diffusion in the suspension. The BIOMICS experi-ment in the MASER 11 sounding rocket revealed a complex spatial structure of a polydisperse vesicle suspension due to the interplay between lift forces from the walls and hydrodynamic interactions. These phenomena have a strong impact on the structure and rheology of blood in small vessels, and a precise knowledge of the dynamics of migration and diffusion of soft particles in flow can lead to alternative ways to separate and sort blood cells. 1. Dubois, F., Schockaert, C., Callens, N., Yourrassowsky, C., "Focus plane detection criteria in digital holography microscopy by amplitude analysis", Opt. Express, Vol. 14, pp 5895-5908, 2006 2. Callens, N., Minetti, C., Coupier, G., Mader, M.-A., Dubois, F., Misbah, C., Podgorski, T., "Hydrodynamics lift of vesicles under shear flow in microgravity", Europhys. Lett., Vol. 83, p. 24002, 2008

Easily constructed spectroelectrochemical cell for batch and flow injection analyses.

PubMed

Flowers, Paul A; Maynor, Margaret A; Owens, Donald E

2002-02-01

The design and performance of an easily constructed spectroelectrochemical cell suitable for batch and flow injection measurements are described. The cell is fabricated from a commercially available 5-mm quartz cuvette and employs 60 ppi reticulated vitreous carbon as the working electrode, resulting in a reasonable compromise between optical sensitivity and thin-layer electrochemical behavior. The spectroelectrochemical traits of the cell in both batch and flow modes were evaluated using aqueous ferricyanide and compare favorably to those reported previously for similar cells.

Elucidation of flow-mediated tumour cell-induced platelet aggregation using an ultrasound standing wave trap.

PubMed

Bazou, D; Santos-Martinez, M J; Medina, C; Radomski, M W

2011-04-01

Tumour cells activate and aggregate platelets [tumour cell-induced platelet aggregation (TCIPA)] and this process plays an important role in the successful metastasis of cancer cells. To date, most studies on TCIPA have been conducted under no-flow conditions. In this study, we have investigated TCIPA in real time under flow conditions, using an ultrasound standing wave trap that allows formation and levitation of cancer cell clusters in suspension, thus mimicking the conditions generated by flowing blood. Using 59M adenocarcinoma and HT1080 fibrosarcoma cells and human platelets, cancer cell cluster-platelet aggregates were imaged in real time using epi-fluorescence microscopy (F-actin) and investigated in detail using confocal microscopy (matrix metalloproteinase-2-GPIIb/IIIa co-localization) and scanning electron and helium-ion microscopy (<1 nm resolution). The release of gelatinases from aggregates was studied using zymography. We found that platelet activation and aggregation takes place on the surface of cancer cells (TCIPA), leading to time-dependent disruption of cancer cell clusters. Pharmacological modulation of TCIPA revealed that EDTA, prostacyclin, o-phenanthroline and apyrase significantly down-regulated TCIPA and, in turn, delayed cell cluster disruption, However, EGTA and aspirin were ineffective. Pharmacological inhibition of TCIPA correlated with the down-regulation of platelet activation as shown by flow-cytometry assay of platelet P-selectin. Our results show for the first time, that during TCIPA, platelet activation disrupts cancer cell clusters and this can contribute to metastasis. Thus, selective targeting of platelet aggregate-cancer cell clusters may be an important strategy to control metastasis. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

Elucidation of flow-mediated tumour cell-induced platelet aggregation using an ultrasound standing wave trap

PubMed Central

Bazou, D; Santos-Martinez, MJ; Medina, C; Radomski, MW

2011-01-01

BACKGROUND AND PURPOSE Tumour cells activate and aggregate platelets [tumour cell-induced platelet aggregation (TCIPA)] and this process plays an important role in the successful metastasis of cancer cells. To date, most studies on TCIPA have been conducted under no-flow conditions. In this study, we have investigated TCIPA in real time under flow conditions, using an ultrasound standing wave trap that allows formation and levitation of cancer cell clusters in suspension, thus mimicking the conditions generated by flowing blood. EXPERIMENTAL APPROACH Using 59M adenocarcinoma and HT1080 fibrosarcoma cells and human platelets, cancer cell cluster–platelet aggregates were imaged in real time using epi-fluorescence microscopy (F-actin) and investigated in detail using confocal microscopy (matrix metalloproteinase-2-GPIIb/IIIa co-localization) and scanning electron and helium-ion microscopy (<1 nm resolution). The release of gelatinases from aggregates was studied using zymography. KEY RESULTS We found that platelet activation and aggregation takes place on the surface of cancer cells (TCIPA), leading to time-dependent disruption of cancer cell clusters. Pharmacological modulation of TCIPA revealed that EDTA, prostacyclin, o-phenanthroline and apyrase significantly down-regulated TCIPA and, in turn, delayed cell cluster disruption, However, EGTA and aspirin were ineffective. Pharmacological inhibition of TCIPA correlated with the down-regulation of platelet activation as shown by flow-cytometry assay of platelet P-selectin. CONCLUSION AND IMPLICATIONS Our results show for the first time, that during TCIPA, platelet activation disrupts cancer cell clusters and this can contribute to metastasis. Thus, selective targeting of platelet aggregate–cancer cell clusters may be an important strategy to control metastasis. PMID:21182493

Proteomic analysis of exosomes from human neural stem cells by flow field-flow fractionation and nanoflow liquid chromatography-tandem mass spectrometry.

PubMed

Kang, Dukjin; Oh, Sunok; Ahn, Sung-Min; Lee, Bong-Hee; Moon, Myeong Hee

2008-08-01

Exosomes, small membrane vesicles secreted by a multitude of cell types, are involved in a wide range of physiological roles such as intercellular communication, membrane exchange between cells, and degradation as an alternative to lysosomes. Because of the small size of exosomes (30-100 nm) and the limitations of common separation procedures including ultracentrifugation and flow cytometry, size-based fractionation of exosomes has been challenging. In this study, we used flow field-flow fractionation (FlFFF) to fractionate exosomes according to differences in hydrodynamic diameter. The exosome fractions collected from FlFFF runs were examined by transmission electron microscopy (TEM) to morphologically confirm their identification as exosomes. Exosomal lysates of each fraction were digested and analyzed using nanoflow LC-ESI-MS-MS for protein identification. FIFFF, coupled with mass spectrometry, allows nanoscale size-based fractionation of exosomes and is more applicable to primary cells and stem cells since it requires much less starting material than conventional gel-based separation, in-gel digestion and the MS-MS method.

Flow-enhanced solution printing of all-polymer solar cells

DOE PAGES

Diao, Ying; Zhou, Yan; Kurosawa, Tadanori; ...

2015-08-12

Morphology control of solution coated solar cell materials presents a key challenge limiting their device performance and commercial viability. Here we present a new concept for controlling phase separation during solution printing using an all-polymer bulk heterojunction solar cell as a model system. The key aspect of our method lies in the design of fluid flow using a microstructured printing blade, on the basis of the hypothesis of flow-induced polymer crystallization. Our flow design resulted in a similar to 90% increase in the donor thin film crystallinity and reduced microphase separated donor and acceptor domain sizes. The improved morphology enhancedmore » all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation. However, we expect our design concept to have broad applications beyond all-polymer solar cells because of its simplicity and versatility.« less

Flow-enhanced solution printing of all-polymer solar cells

PubMed Central

Diao, Ying; Zhou, Yan; Kurosawa, Tadanori; Shaw, Leo; Wang, Cheng; Park, Steve; Guo, Yikun; Reinspach, Julia A.; Gu, Kevin; Gu, Xiaodan; Tee, Benjamin C. K.; Pang, Changhyun; Yan, Hongping; Zhao, Dahui; Toney, Michael F.; Mannsfeld, Stefan C. B.; Bao, Zhenan

2015-01-01

Morphology control of solution coated solar cell materials presents a key challenge limiting their device performance and commercial viability. Here we present a new concept for controlling phase separation during solution printing using an all-polymer bulk heterojunction solar cell as a model system. The key aspect of our method lies in the design of fluid flow using a microstructured printing blade, on the basis of the hypothesis of flow-induced polymer crystallization. Our flow design resulted in a ∼90% increase in the donor thin film crystallinity and reduced microphase separated donor and acceptor domain sizes. The improved morphology enhanced all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation. We expect our design concept to have broad applications beyond all-polymer solar cells because of its simplicity and versatility. PMID:26264528

In vitro Flow Adhesion Assay for Analyzing Shear-resistant Adhesion of Metastatic Cancer Cells to Endothelial Cells.

PubMed

Kang, Shin-Ae; Bajana, Sandra; Tanaka, Takemi

2016-02-20

Hematogenous metastasis is a primary cause of mortality from metastatic cancer. The shear-resistant adhesion of circulating tumor cells to the vascular endothelial cell surface under blood flow is an essential step in cell extravasation and further tissue invasion. This is similar to a process exploited by leukocytes for adhesion to inflamed blood vessels (leukocyte mimicry). The shear resistant adhesion is mediated by high affinity interactions between endothelial adhesion molecules and their counter receptor ligand expressed on circulating cells. Thus, weak interaction results in a rapid detachment of circulating cells from endothelium. Despite the critical role of vascular adhesion of cancer cells in hematogenous metastasis, our knowledge regarding this process has been limited due to the difficulty of mimicking dynamic flow conditions in vitro . In order to gain better insight into the shear-resistant adhesion of cancer cells to the endothelium, we developed a protocol for measuring the shear resistant adhesion of circulating tumor cells to endothelial cells under physiologic flow conditions by adapting a well established flow adhesion assay for inflammatory cells. This technique is useful to evaluate 1) the shear resistant adhesion competency of cancer cells and 2) the endothelial adhesion molecules necessary to support cancer cell adhesion (Kang et al. , 2015).

Biology and flow cytometry of proangiogenic hematopoietic progenitors cells.

PubMed

Rose, Jonathan A; Erzurum, Serpil; Asosingh, Kewal

2015-01-01

During development, hematopoiesis and neovascularization are closely linked to each other via a common bipotent stem cell called the hemangioblast that gives rise to both hematopoietic cells and endothelial cells. In postnatal life, this functional connection between the vasculature and hematopoiesis is maintained by a subset of hematopoietic progenitor cells endowed with the capacity to differentiate into potent proangiogenic cells. These proangiogenic hematopoietic progenitors comprise a specific subset of bone marrow (BM)-derived cells that homes to sites of neovascularization and possess potent paracrine angiogenic activity. There is emerging evidence that this subpopulation of hematopoietic progenitors plays a critical role in vascular health and disease. Their angiogenic activity is distinct from putative "endothelial progenitor cells" that become structural cells of the endothelium by differentiation into endothelial cells. Proangiogenic hematopoietic progenitor cell research requires multidisciplinary expertise in flow cytometry, hematology, and vascular biology. This review provides a comprehensive overview of proangiogenic hematopoietic progenitor cell biology and flow cytometric methods to detect these cells in the peripheral blood circulation and BM. © 2014 International Society for Advancement of Cytometry.

A six-colour flow cytometric method for simultaneous detection of cell phenotype and apoptosis of circulating endothelial cells.

PubMed

Mariucci, S; Rovati, B; Chatzileontiadou, S; Bencardino, K; Manzoni, M; Delfanti, S; Danova, M

2009-01-01

Blood circulating endothelial cells (CECs), with their resting and activated subsets, (rCECs and aCECs) and circulating progenitors cells (CEPs) are two extremely rare cell populations that are important in tissue vascularization. Their number and function are modulated in diseases involving vascular injury, such as human tumours. Although a consensus on the phenotypic definition of endothelial cells, as well as on the optimal enumeration technique, is still lacking, the number of clinical studies based on assessment of these cells is rapidly expanding, as well as the analytical methods employed. The present study aimed to develop a rapid and sensitive flow cytometric method of quantifying and characterizing CECs (with both their subsets and the apoptotic fraction) and CEPs. We analysed peripheral blood samples from 21 subjects with a six-colour flow cytometric approach allowing detection of the cell phenotype of CECs and CEPs using a monoclonal antibodies panel and a dedicated gating strategy. Apoptotic CECs were detected with Annexin V and dead cells with 7-amino-actinomycin D staining. The described technique proved to be a new, reliable, tool increasing our knowledge of the biology of CECs and CEPs and can readily be applied in the study of many pathological conditions characterized by endothelial damage.

Collision Based Blood Cell Distribution of the Blood Flow

NASA Astrophysics Data System (ADS)

Cinar, Yildirim

2003-11-01

Introduction: The goal of the study is the determination of the energy transferring process between colliding masses and the application of the results to the distribution of the cell, velocity and kinetic energy in arterial blood flow. Methods: Mathematical methods and models were used to explain the collision between two moving systems, and the distribution of linear momentum, rectilinear velocity, and kinetic energy in a collision. Results: According to decrease of mass of the second system, the velocity and momentum of constant mass of the first system are decreased, and linearly decreasing mass of the second system captures a larger amount of the kinetic energy and the rectilinear velocity of the collision system on a logarithmic scale. Discussion: The cause of concentration of blood cells at the center of blood flow an artery is not explained by Bernoulli principle alone but the kinetic energy and velocity distribution due to collision between the big mass of the arterial wall and the small mass of blood cells must be considered as well.

Pockels-effect cell for gas-flow simulation

NASA Astrophysics Data System (ADS)

Weimer, D.

1982-05-01

A Pockels effect cell using a 75 cu cm DK*P crystal was developed and used as a gas flow simulator. Index of refraction gradients were produced in the cell by the fringing fields of parallel plate electrodes. Calibration curves for the device were obtained for index of refraction gradients in excess of .00025 m.

A 3D Culture Model to Study How Fluid Pressure and Flow Affect the Behavior of Aggregates of Epithelial Cells.

PubMed

Piotrowski-Daspit, Alexandra S; Simi, Allison K; Pang, Mei-Fong; Tien, Joe; Nelson, Celeste M

2017-01-01

Cells are surrounded by mechanical stimuli in their microenvironment. It is important to determine how cells respond to the mechanical information that surrounds them in order to understand both development and disease progression, as well as to be able to predict cell behavior in response to physical stimuli. Here we describe a protocol to determine the effects of interstitial fluid flow on the migratory behavior of an aggregate of epithelial cells in a three-dimensional (3D) culture model. This protocol includes detailed methods for the fabrication of a 3D cell culture chamber with hydrostatic pressure control, the culture of epithelial cells as an aggregate in a collagen gel, and the analysis of collective cell behavior in response to pressure-driven flow.

A study of disequilibrium between 220Rn and 216Po for 220Rn measurements using a flow-through Lucas scintillation cell.

PubMed

Sathyabama, N; Datta, D; Gaware, J J; Mayya, Y S; Tripathi, R M

2014-01-01

Lucas-type scintillation cells (LSCs) are commonly used for rapid measurements of (220)Rn concentrations in flow-through mode in field and for calibration experiments in laboratories. However, in those measurements, equilibrium between (220)Rn and (216)Po is generally assumed and two alpha particles are considered to be emitted per (220)Rn decay due to very short half-life of (216)Po. In this paper, a small, yet significant disequilibrium existing between (220)Rn and (216)Po has been examined and shown that less than two alpha particles are actually emitted per (220)Rn decay in the cell when flow is maintained. A theoretical formula has been derived for the first time for a correction factor (CF) to be applied to this measured concentration to account for the disequilibrium. The existence of this disequilibrium has been verified experimentally and is found to increase with the increase in the ratio of flow rate to cell volume. The reason for the disequilibrium is attributed to the flushing out of (216)Po formed in the cell before its decay due to the flow. Uncertainties in measured concentrations have been estimated and the estimated CF values have been found to be significant for the flow rates considered above 5 dm(3) min(-1) for a cell of volume 0.125 dm(3). The calculated values of the CF are about 1.055 to 1.178 in the flow rate range of 4 to 15 dm(3) min(-1) for the cell of volume 0.125 dm(3), while the corresponding experimental values are 1.023 to 1.264. This is a systematic error introduced in (220)Rn measurements using a flow-through LSC, which can be removed either by correct formulation or by proper design of a measurement set-up.

A fluid–structure interaction model to characterize bone cell stimulation in parallel-plate flow chamber systems

PubMed Central

Vaughan, T. J.; Haugh, M. G.; McNamara, L. M.

2013-01-01

Bone continuously adapts its internal structure to accommodate the functional demands of its mechanical environment and strain-induced flow of interstitial fluid is believed to be the primary mediator of mechanical stimuli to bone cells in vivo. In vitro investigations have shown that bone cells produce important biochemical signals in response to fluid flow applied using parallel-plate flow chamber (PPFC) systems. However, the exact mechanical stimulus experienced by the cells within these systems remains unclear. To fully understand this behaviour represents a most challenging multi-physics problem involving the interaction between deformable cellular structures and adjacent fluid flows. In this study, we use a fluid–structure interaction computational approach to investigate the nature of the mechanical stimulus being applied to a single osteoblast cell under fluid flow within a PPFC system. The analysis decouples the contribution of pressure and shear stress on cellular deformation and for the first time highlights that cell strain under flow is dominated by the pressure in the PPFC system rather than the applied shear stress. Furthermore, it was found that strains imparted on the cell membrane were relatively low whereas significant strain amplification occurred at the cell–substrate interface. These results suggest that strain transfer through focal attachments at the base of the cell are the primary mediators of mechanical signals to the cell under flow in a PPFC system. Such information is vital in order to correctly interpret biological responses of bone cells under in vitro stimulation and elucidate the mechanisms associated with mechanotransduction in vivo. PMID:23365189

miRNA detection at single-cell resolution using microfluidic LNA flow-FISH

DOE PAGES

Wu, Meiye; Piccini, Matthew Ernest; Koh, Chung -Yan; ...

2014-08-20

Flow cytometry in combination with fluorescent in situ hybridization (flow-FISH) is a powerful technique that can be utilized to rapidly detect nucleic acids at single-cell resolution without the need for homogenization or nucleic acid extraction. Here, we describe a microfluidic-based method which enables the detection of microRNAs or miRNAs in single intact cells by flow-FISH using locked nucleic acid (LNA)-containing probes. Our method can be applied to all RNA species including mRNA and small noncoding RNA and is suitable for multiplexing with protein immunostaining in the same cell. For demonstration of our method, this chapter details the detection of miR155more » and CD69 protein in PMA and ionomycin-stimulated Jurkat cells. Here, we also include instructions on how to set up a microfluidic chip sample preparation station to prepare cells for imaging and analysis on a commercial flow cytometer or a custom-built micro-flow cytometer.« less

Flow-Cell-Induced Dispersion in Flow-through Absorbance Detection Systems: True Column Effluent Peak Variance.

PubMed

Dasgupta, Purnendu K; Shelor, Charles Phillip; Kadjo, Akinde Florence; Kraiczek, Karsten G

2018-02-06

Following a brief overview of the emergence of absorbance detection in liquid chromatography, we focus on the dispersion caused by the absorbance measurement cell and its inlet. A simple experiment is proposed wherein chromatographic flow and conditions are held constant but a variable portion of the column effluent is directed into the detector. The temporal peak variance (σ t,obs 2 ), which increases as the flow rate (F) through the detector decreases, is found to be well-described as a quadratic function of 1 / F . This allows the extrapolation of the results to zero residence time in the detector and thence the determination of the true variance of the peak prior to the detector (this includes contribution of all preceding components). This general approach should be equally applicable to detection systems other than absorbance. We also experiment where the inlet/outlet system remains the same but the path length is varied. This allows one to assess the individual contributions of the cell itself and the inlet/outlet system.to the total observed peak. The dispersion in the cell itself has often been modeled as a flow-independent parameter, dependent only on the cell volume. Except for very long path/large volume cells, this paradigm is simply incorrect.

A high precision gas flow cell for performing in situ neutron studies of local atomic structure in catalytic materials

DOE PAGES

Olds, Daniel; Page, Katharine; Paecklar, Arnold A.; ...

2017-03-17

Gas-solid interfaces enable a multitude of industrial processes, including heterogeneous catalysis; however, there are few methods available for studying the structure of this interface under operating conditions. Here, we present a new sample environment for interrogating materials under gas-flow conditions using time-of-flight neutron scattering under both constant and pulse probe gas flow. Outlined are descriptions of the gas flow cell and a commissioning example using the adsorption of N 2 by Ca-exchanged zeolite-X (Na 78–2xCa xAl 78Si 144O 384,x ≈ 38). We demonstrate sensitivities to lattice contraction and N 2 adsorption sites in the structure, with both static gas loadingmore » and gas flow. A steady-state isotope transient kinetic analysis of N 2 adsorption measured simultaneously with mass spectrometry is also demonstrated. In the experiment, the gas flow through a plugged-flow gas-solid contactor is switched between 15N 2 and 14N 2 isotopes at a temperature of 300 K and a constant pressure of 1 atm; the gas flow and mass spectrum are correlated with the structure factor determined from event-based neutron total scattering. As a result, available flow conditions, sample considerations, and future applications are discussed.« less

Fuel cell with interdigitated porous flow-field

DOEpatents

Wilson, Mahlon S.

1997-01-01

A polymer electrolyte membrane (PEM) fuel cell is formed with an improved system for distributing gaseous reactants to the membrane surface. A PEM fuel cell has an ionic transport membrane with opposed catalytic surfaces formed thereon and separates gaseous reactants that undergo reactions at the catalytic surfaces of the membrane. The fuel cell may also include a thin gas diffusion layer having first and second sides with a first side contacting at least one of the catalytic surfaces. A macroporous flow-field with interdigitated inlet and outlet reactant channels contacts the second side of the thin gas diffusion layer for distributing one of the gaseous reactants over the thin gas diffusion layer for transport to an adjacent one of the catalytic surfaces of the membrane. The porous flow field may be formed from a hydrophilic material and provides uniform support across the backside of the electrode assembly to facilitate the use of thin backing layers.

Fuel cell with interdigitated porous flow-field

DOEpatents

Wilson, M.S.

1997-06-24

A polymer electrolyte membrane (PEM) fuel cell is formed with an improved system for distributing gaseous reactants to the membrane surface. A PEM fuel cell has an ionic transport membrane with opposed catalytic surfaces formed thereon and separates gaseous reactants that undergo reactions at the catalytic surfaces of the membrane. The fuel cell may also include a thin gas diffusion layer having first and second sides with a first side contacting at least one of the catalytic surfaces. A macroporous flow-field with interdigitated inlet and outlet reactant channels contacts the second side of the thin gas diffusion layer for distributing one of the gaseous reactants over the thin gas diffusion layer for transport to an adjacent one of the catalytic surfaces of the membrane. The porous flow field may be formed from a hydrophilic material and provides uniform support across the backside of the electrode assembly to facilitate the use of thin backing layers. 9 figs.

Two problems in multiphase biological flows: Blood flow and particulate transport in microvascular network, and pseudopod-driven motility of amoeboid cells

NASA Astrophysics Data System (ADS)

Bagchi, Prosenjit

2016-11-01

In this talk, two problems in multiphase biological flows will be discussed. The first is the direct numerical simulation of whole blood and drug particulates in microvascular networks. Blood in microcirculation behaves as a dense suspension of heterogeneous cells. The erythrocytes are extremely deformable, while inactivated platelets and leukocytes are nearly rigid. A significant progress has been made in recent years in modeling blood as a dense cellular suspension. However, many of these studies considered the blood flow in simple geometry, e.g., straight tubes of uniform cross-section. In contrast, the architecture of a microvascular network is very complex with bifurcating, merging and winding vessels, posing a further challenge to numerical modeling. We have developed an immersed-boundary-based method that can consider blood cell flow in physiologically realistic and complex microvascular network. In addition to addressing many physiological issues related to network hemodynamics, this tool can be used to optimize the transport properties of drug particulates for effective organ-specific delivery. Our second problem is pseudopod-driven motility as often observed in metastatic cancer cells and other amoeboid cells. We have developed a multiscale hydrodynamic model to simulate such motility. We study the effect of cell stiffness on motility as the former has been considered as a biomarker for metastatic potential. Funded by the National Science Foundation.

Peclet number analysis of cross-flow in porous gas diffusion layer of polymer electrolyte membrane fuel cell (PEMFC).

PubMed

Suresh, P V; Jayanti, Sreenivas

2016-10-01

Adoption of hydrogen economy by means of using hydrogen fuel cells is one possible solution for energy crisis and climate change issues. Polymer electrolyte membrane (PEM) fuel cell, which is an important type of fuel cells, suffers from the problem of water management. Cross-flow is induced in some flow field designs to enhance the water removal. The presence of cross-flow in the serpentine and interdigitated flow fields makes them more effective in proper distribution of the reactants on the reaction layer and evacuation of water from the reaction layer than diffusion-based conventional parallel flow fields. However, too much of cross-flow leads to flow maldistribution in the channels, higher pressure drop, and membrane dehydration. In this study, an attempt has been made to quantify the amount of cross-flow required for effective distribution of reactants and removal of water in the gas diffusion layer. Unit cells containing two adjacent channels with gas diffusion layer (GDL) and catalyst layer at the bottom have been considered for the parallel, interdigitated, and serpentine flow patterns. Computational fluid dynamics-based simulations are carried out to study the reactant transport in under-the-rib area with cross-flow in the GDL. A new criterion based on the Peclet number is presented as a quantitative measure of cross-flow in the GDL. The study shows that a cross-flow Peclet number of the order of 2 is required for effective removal of water from the GDL. Estimates show that this much of cross-flow is not usually produced in the U-bends of Serpentine flow fields, making these areas prone to flooding.

An analytical study of reduced-gravity flow dynamics

NASA Technical Reports Server (NTRS)

Bradshaw, R. D.; Kramer, J. L.; Zich, J. L.

1976-01-01

Addition of surface tension forces to a marker-and-cell code and the performance of four incompressible fluid simulations in reduced gravity, were studied. This marker-and-cell code has a variable grid capability with arbitrary curved boundaries and time dependent acceleration fields. The surface tension logic includes a spline fit of surface marker particles as well as contact angle logic for straight and curved wall boundaries. Three types of flow motion were simulated with the improved code: impulsive settling in a model Centaur LH2 tank, continuous settling in a model and full scale Centaur LO2 tank and mixing in a Centaur LH2 tank. The impulsive settling case confirmed a drop tower analysis which indicated more orderly fluid collection flow patterns with this method providing a potential savings in settling propellants. In the LO2 tank, fluid collection and flow simulation into the thrust barrel were achieved. The mixing simulation produced good results indicating both the development of the flow field and fluid interface behavior.

Flow-Mediated Stem Cell Labeling with Superparamagnetic Iron Oxide Nanoparticle Clusters

PubMed Central

Shkumatov, Artem; Lai, Mei-Hsiu; Smith, Cartney E.; Rich, Max; Kong, Hyunjoon

2013-01-01

This study presents a strategy to enhance the uptake of superparamagnetic iron oxide nanoparticle (SPIO) clusters by manipulating the cellular mechanical environment. Specifically, stem cells exposed to an orbital flow ingested almost two-fold greater amount of SPIO clusters than those cultured statically. Improvements in MR contrast were subsequently achieved for labeled cells in collagen gels and a mouse model. Overall, this strategy will serve to improve the efficiency of cell tracking and therapies. PMID:24033276

FLOCK cluster analysis of plasma cell flow cytometry data predicts bone marrow involvement by plasma cell neoplasia.

PubMed

Dorfman, David M; LaPlante, Charlotte D; Li, Betty

2016-09-01

We analyzed plasma cell populations in bone marrow samples from 353 patients with possible bone marrow involvement by a plasma cell neoplasm, using FLOCK (FLOw Clustering without K), an unbiased, automated, computational approach to identify cell subsets in multidimensional flow cytometry data. FLOCK identified discrete plasma cell populations in the majority of bone marrow specimens found by standard histologic and immunophenotypic criteria to be involved by a plasma cell neoplasm (202/208 cases; 97%), including 34 cases that were negative by standard flow cytometric analysis that included clonality assessment. FLOCK identified discrete plasma cell populations in only a minority of cases negative for involvement by a plasma cell neoplasm by standard histologic and immunophenotypic criteria (38/145 cases; 26%). Interestingly, 55% of the cases negative by standard analysis, but containing a FLOCK-identified discrete plasma cell population, were positive for monoclonal gammopathy by serum protein electrophoresis and immunofixation. FLOCK-identified and quantitated plasma cell populations accounted for 3.05% of total cells on average in cases positive for involvement by a plasma cell neoplasm by standard histologic and immunophenotypic criteria, and 0.27% of total cells on average in cases negative for involvement by a plasma cell neoplasm by standard histologic and immunophenotypic criteria (p<0.0001; area under the curve by ROC analysis=0.96). The presence of a FLOCK-identified discrete plasma cell population was predictive of the presence of plasma cell neoplasia with a sensitivity of 97%, compared with only 81% for standard flow cytometric analysis, and had specificity of 74%, PPV of 84% and NPV of 95%. FLOCK analysis, which has been shown to provide useful diagnostic information for evaluating patients with suspected systemic mastocytosis, is able to identify neoplastic plasma cell populations analyzed by flow cytometry, and may be helpful in the diagnostic

Quantitative analysis of gold and carbon nanoparticles in mammalian cells by flow cytometry light scattering

NASA Astrophysics Data System (ADS)

Zhou, Gang; Liu, Naicheng; Wang, Zhenheng; Shi, Tongguo; Gan, Jingjing; Wang, Zhenzhen; Zhang, Junfeng

2017-02-01

Nanoparticle-based applications for diagnostics and therapeutics have been extensively studied. These applications require a profound understanding of the fate of nanoparticles (NPs) in cellular environments. However, until now, few analytical methods are available and most of them rely on fluorescent properties or special elements of NPs; therefore, for NPs without observable optical properties or special elements, the existing methods are hardly applicable. In this study, we introduce a flow cytometry light scattering (FCLS)-based approach that quantifies in situ NPs accurately in mammalian cells. Continuous cells of heterogeneous human epithelial colorectal adenocarcinoma (Caco-2 cells), mouse peritoneal macrophages (MPM), and human adenocarcinomic alveolar basal epithelia (A549 cells) were cultured with NPs with certain concentrations and size. The intensity of the flow cytometric side scattered light, which indicates the quantity of NPs in the cells, was analyzed. The result shows an accurate size- and dose-dependent uptake of Au NPs (5, 30, 250 nm) in Caco-2 cells. The size- and dose- dependence of Au NPs (5, 30, 250 nm) and carbon NPs (50, 500 nm) in cells was validated by transmission electron microscope (TEM). This paper demonstrates the great potential of flow cytometry light scattering in the quantitative study of the size and dose effect on in situ metallic or non-metallic NPs in mammalian cells.

Flow of a circulating tumor cell and red blood cells in microvessels

NASA Astrophysics Data System (ADS)

Takeishi, Naoki; Imai, Yohsuke; Yamaguchi, Takami; Ishikawa, Takuji

2015-12-01

Quantifying the behavior of circulating tumor cells (CTCs) in the blood stream is of fundamental importance for understanding metastasis. Here, we investigate the flow mode and velocity of CTCs interacting with red blood cells (RBCs) in various sized microvessels. The flow of leukocytes in microvessels has been described previously; a leukocyte forms a train with RBCs in small microvessels and exhibits margination in large microvessels. Important differences in the physical properties of leukocytes and CTCs result from size. The dimensions of leukocytes are similar to those of RBCs, but CTCs are significantly larger. We investigate numerically the size effects on the flow mode and the cell velocity, and we identify similarities and differences between leukocytes and CTCs. We find that a transition from train formation to margination occurs when (R -a ) /tR≈1 , where R is the vessel radius, a is the cell radius, and tR is the thickness of RBCs, but that the motion of RBCs differs from the case of leukocytes. Our results also show that the velocities of CTCs and leukocytes are larger than the average blood velocity, but only CTCs move faster than RBCs for microvessels of R /a ≈1.5 -2.0 . These findings are expected to be useful not only for understanding metastasis, but also for developing microfluidic devices.

Capture of circulating tumor cells using photoacoustic flowmetry and two phase flow

NASA Astrophysics Data System (ADS)

O'Brien, Christine M.; Rood, Kyle D.; Bhattacharyya, Kiran; DeSouza, Thiago; Sengupta, Shramik; Gupta, Sagar K.; Mosley, Jeffrey D.; Goldschmidt, Benjamin S.; Sharma, Nikhilesh; Viator, John A.

2012-06-01

Melanoma is the deadliest form of skin cancer, yet current diagnostic methods are unable to detect early onset of metastatic disease. Patients must wait until macroscopic secondary tumors form before malignancy can be diagnosed and treatment prescribed. Detection of cells that have broken off the original tumor and travel through the blood or lymph system can provide data for diagnosing and monitoring metastatic disease. By irradiating enriched blood samples spiked with cultured melanoma cells with nanosecond duration laser light, we induced photoacoustic responses in the pigmented cells. Thus, we can detect and enumerate melanoma cells in blood samples to demonstrate a paradigm for a photoacoustic flow cytometer. Furthermore, we capture the melanoma cells using microfluidic two phase flow, a technique that separates a continuous flow into alternating microslugs of air and blood cell suspension. Each slug of blood cells is tested for the presence of melanoma. Slugs that are positive for melanoma, indicated by photoacoustic waves, are separated from the cytometer for further purification and isolation of the melanoma cell. In this paper, we evaluate the two phase photoacoustic flow cytometer for its ability to detect and capture metastastic melanoma cells in blood.

Photoacoustic-fluorescence in vitro flow cytometry for quantification of absorption, scattering and fluorescence properties of the cells

NASA Astrophysics Data System (ADS)

Nedosekin, D. A.; Sarimollaoglu, M.; Foster, S.; Galanzha, E. I.; Zharov, V. P.

2013-03-01

Fluorescence flow cytometry is a well-established analytical tool that provides quantification of multiple biological parameters of cells at molecular levels, including their functional states, morphology, composition, proliferation, and protein expression. However, only the fluorescence and scattering parameters of the cells or labels are available for detection. Cell pigmentation, presence of non-fluorescent dyes or nanoparticles cannot be reliably quantified. Herewith, we present a novel photoacoustic (PA) flow cytometry design for simple integration of absorbance measurements into schematics of conventional in vitro flow cytometers. The integrated system allow simultaneous measurements of light absorbance, scattering and of multicolor fluorescence from single cells in the flow at rates up to 2 m/s. We compared various combinations of excitation laser sources for multicolor detection, including simultaneous excitation of PA and fluorescence using a single 500 kHz pulsed nanosecond laser. Multichannel detection scheme allows simultaneous detection of up to 8 labels, including 4 fluorescent tags and 4 PA colors. In vitro PA-fluorescence flow cytometer was used for studies of nanoparticles uptake and for the analysis of cell line pigmentation, including genetically encoded melanin expression in breast cancer cell line. We demonstrate that this system can be used for direct nanotoxicity studies with simultaneous quantification of nanoparticles content and assessment of cell viability using a conventional fluorescent apoptosis assays.

Combined Microfluidic-Eectric Diffused Mixing of Living Cells in Continuous Flow

NASA Astrophysics Data System (ADS)

Ming-Wen Wang,

2010-02-01

The mixing process is a crucially important stage in the operation of biological and chemical microfluidic devices. If the mixing is inadequate, reactants do not fully interact with each other, and the device may not operate properly. This paper describes a simplified microfluidic mixer (different from a chaotic mixer) which can uniformly mix a buffer solution with living cells by applying an AC electric charge. Diffusion of the living cells into the buffer solution occurs rapidly following the interface of the flow stream with the electric charge; no further agitating step is needed. To accomplish this, an asymmetric pair of electrodes was integrated at the inlets of the buffer solution and the cells fluid. When the buffer solution and the cells fluid were introduced into one flow path, they remained limited to that flow stream. When the electrodes were charged, however, the cells in a short distance were efficiently moved into the solution flow, and the original fluids were mixed. The mixing efficiency depends on the polarizability of the cells, and this in turn is governed by the dielectric properties of the cells, the medium, and the solvent. This micro device, capable of efficiently mixing living cells with a buffer solution, may potentially allow biological mixing to be done outside of hospitals, in facilities without biological analyzing instruments.

PolNet: A Tool to Quantify Network-Level Cell Polarity and Blood Flow in Vascular Remodeling.

PubMed

Bernabeu, Miguel O; Jones, Martin L; Nash, Rupert W; Pezzarossa, Anna; Coveney, Peter V; Gerhardt, Holger; Franco, Claudio A

2018-05-08

In this article, we present PolNet, an open-source software tool for the study of blood flow and cell-level biological activity during vessel morphogenesis. We provide an image acquisition, segmentation, and analysis protocol to quantify endothelial cell polarity in entire in vivo vascular networks. In combination, we use computational fluid dynamics to characterize the hemodynamics of the vascular networks under study. The tool enables, to our knowledge for the first time, a network-level analysis of polarity and flow for individual endothelial cells. To date, PolNet has proven invaluable for the study of endothelial cell polarization and migration during vascular patterning, as demonstrated by two recent publications. Additionally, the tool can be easily extended to correlate blood flow with other experimental observations at the cellular/molecular level. We release the source code of our tool under the Lesser General Public License. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

NASA Non-Flow-Through PEM Fuel Cell System for Aerospace Applications

NASA Technical Reports Server (NTRS)

Araghi, Koorosh R.

2011-01-01

NASA is researching passive NFT Proton Exchange Membrane (PEM) fuel cell technologies for primary fuel cell power plants in air-independent applications. NFT fuel cell power systems have a higher power density than flow through systems due to both reduced parasitic loads and lower system mass and volume. Reactant storage still dominates system mass/volume considerations. NFT fuel cell stack testing has demonstrated equivalent short term performance to flow through stacks. More testing is required to evaluate long-term performance.

Sequential CD34 cell fractionation by magnetophoresis in a magnetic dipole flow sorter.

PubMed

Schneider, Thomas; Karl, Stephan; Moore, Lee R; Chalmers, Jeffrey J; Williams, P Stephen; Zborowski, Maciej

2010-01-01

Cell separation and fractionation based on fluorescent and magnetic labeling procedures are common tools in contemporary research. These techniques rely on binding of fluorophores or magnetic particles conjugated to antibodies to target cells. Cell surface marker expression levels within cell populations vary with progression through the cell cycle. In an earlier work we showed the reproducible magnetic fractionation (single pass) of the Jurkat cell line based on the population distribution of CD45 surface marker expression. Here we present a study on magnetic fractionation of a stem and progenitor cell (SPC) population using the established acute myelogenous leukemia cell line KG-1a as a cell model. The cells express a CD34 cell surface marker associated with the hematopoietic progenitor cell activity and the progenitor cell lineage commitment. The CD34 expression level is approximately an order of magnitude lower than that of the CD45 marker, which required further improvements of the magnetic fractionation apparatus. The cells were immunomagnetically labeled using a sandwich of anti-CD34 antibody-phycoerythrin (PE) conjugate and anti-PE magnetic nanobead and fractionated into eight components using a continuous flow dipole magnetophoresis apparatus. The CD34 marker expression distribution between sorted fractions was measured by quantitative PE flow cytometry (using QuantiBRITE PE calibration beads), and it was shown to be correlated with the cell magnetophoretic mobility distribution. A flow outlet addressing scheme based on the concept of the transport lamina thickness was used to control cell distribution between the eight outlet ports. The fractional cell distributions showed good agreement with numerical simulations of the fractionation based on the cell magnetophoretic mobility distribution in the unsorted sample.

Macro- and microscale fluid flow systems for endothelial cell biology.

PubMed

Young, Edmond W K; Simmons, Craig A

2010-01-21

Recent advances in microfluidics have brought forth new tools for studying flow-induced effects on mammalian cells, with important applications in cardiovascular, bone and cancer biology. The plethora of microscale systems developed to date demonstrate the flexibility of microfluidic designs, and showcase advantages of the microscale that are simply not available at the macroscale. However, the majority of these systems will likely not achieve widespread use in the biological laboratory due to their complexity and lack of user-friendliness. To gain widespread acceptance in the biological research community, microfluidics engineers must understand the needs of cell biologists, while biologists must be made aware of available technology. This review provides a critical evaluation of cell culture flow (CCF) systems used to study the effects of mechanical forces on endothelial cells (ECs) in vitro. To help understand the need for various designs of CCF systems, we first briefly summarize main properties of ECs and their native environments. Basic principles of various macro- and microscale systems are described and evaluated. New opportunities are uncovered for developing technologies that have potential to both improve efficiency of experimentation as well as answer important biological questions that otherwise cannot be tackled with existing systems. Finally, we discuss some of the unresolved issues related to microfluidic cell culture, suggest possible avenues of investigation that could resolve these issues, and provide an outlook for the future of microfluidics in biological research.

GLOBAL HELIOSEISMIC EVIDENCE FOR A DEEPLY PENETRATING SOLAR MERIDIONAL FLOW CONSISTING OF MULTIPLE FLOW CELLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schad, A.; Roth, M.; Timmer, J., E-mail: ariane.schad@kis.uni-freiburg.de

2013-12-01

We use a novel global helioseismic analysis method to infer the meridional flow in the deep Solar interior. The method is based on the perturbation of eigenfunctions of Solar p modes due to meridional flow. We apply this method to time series obtained from Dopplergrams measured by the Michelson Doppler Imager aboard the Solar and Heliospheric Observatory covering the observation period 2004-2010. Our results show evidence that the meridional flow reaches down to the base of the convection zone. The flow profile has a complex spatial structure consisting of multiple flow cells distributed in depth and latitude. Toward the Solarmore » surface, our results are in good agreement with flow measurements from local helioseismology.« less

Immersed Boundary Models for Quantifying Flow-Induced Mechanical Stimuli on Stem Cells Seeded on 3D Scaffolds in Perfusion Bioreactors.

PubMed

Guyot, Yann; Smeets, Bart; Odenthal, Tim; Subramani, Ramesh; Luyten, Frank P; Ramon, Herman; Papantoniou, Ioannis; Geris, Liesbet

2016-09-01

Perfusion bioreactors regulate flow conditions in order to provide cells with oxygen, nutrients and flow-associated mechanical stimuli. Locally, these flow conditions can vary depending on the scaffold geometry, cellular confluency and amount of extra cellular matrix deposition. In this study, a novel application of the immersed boundary method was introduced in order to represent a detailed deformable cell attached to a 3D scaffold inside a perfusion bioreactor and exposed to microscopic flow. The immersed boundary model permits the prediction of mechanical effects of the local flow conditions on the cell. Incorporating stiffness values measured with atomic force microscopy and micro-flow boundary conditions obtained from computational fluid dynamics simulations on the entire scaffold, we compared cell deformation, cortical tension, normal and shear pressure between different cell shapes and locations. We observed a large effect of the precise cell location on the local shear stress and we predicted flow-induced cortical tensions in the order of 5 pN/μm, at the lower end of the range reported in literature. The proposed method provides an interesting tool to study perfusion bioreactors processes down to the level of the individual cell's micro-environment, which can further aid in the achievement of robust bioprocess control for regenerative medicine applications.

Needleless connectors substantially reduce flow of crystalloid and red blood cells during rapid infusion.

PubMed

Lehn, Robert A; Gross, Jeffrey B; McIsaac, Joseph H; Gipson, Keith E

2015-04-01

Although needleless connectors (NC) are frequently used in the perioperative setting, the potential of modern NCs to slow delivery of IV fluids has not been thoroughly studied. We examined flow characteristics of 5 NC models during pressurized delivery of crystalloid and banked red blood cells from a Level 1 warmer through various IV catheters. Crystalloid flow rates were reduced by 29% to 85% from control in catheters >18 gauge, while red blood cell flow reductions ranged from 22% to 76% in these catheters (all P < 0.0050). We suggest that practitioners consider eliminating NCs when large IV catheters are inserted for rapid fluid administration.

Factors Released from Endothelial Cells Exposed to Flow Impact Adhesion, Proliferation, and Fate Choice in the Adult Neural Stem Cell Lineage.

PubMed

Dumont, Courtney M; Piselli, Jennifer M; Kazi, Nadeem; Bowman, Evan; Li, Guoyun; Linhardt, Robert J; Temple, Sally; Dai, Guohao; Thompson, Deanna M

2017-08-15

The microvasculature within the neural stem cell (NSC) niche promotes self-renewal and regulates lineage progression. Previous work identified endothelial-produced soluble factors as key regulators of neural progenitor cell (NPC) fate and proliferation; however, endothelial cells (ECs) are sensitive to local hemodynamics, and the effect of this key physiological process has not been defined. In this study, we evaluated adult mouse NPC response to soluble factors isolated from static or dynamic (flow) EC cultures. Endothelial factors generated under dynamic conditions significantly increased neuronal differentiation, while those released under static conditions stimulated oligodendrocyte differentiation. Flow increases EC release of neurogenic factors and of heparin sulfate glycosaminoglycans that increase their bioactivity, likely underlying the enhanced neuronal differentiation. Additionally, endothelial factors, especially from static conditions, promoted adherent growth. Together, our data suggest that blood flow may impact proliferation, adhesion, and the neuron-glial fate choice of adult NPCs, with implications for diseases and aging that reduce flow.

Quantitative passive soil vapor sampling for VOCs--Part 4: Flow-through cell.

PubMed

McAlary, Todd; Groenevelt, Hester; Seethapathy, Suresh; Sacco, Paolo; Crump, Derrick; Tuday, Michael; Schumacher, Brian; Hayes, Heidi; Johnson, Paul; Parker, Louise; Górecki, Tadeusz

2014-05-01

This paper presents a controlled experiment comparing several quantitative passive samplers for monitoring concentrations of volatile organic compound (VOC) vapors in soil gas using a flow-through cell. This application is simpler than conventional active sampling using adsorptive tubes because the flow rate does not need to be precisely measured and controlled, which is advantageous because the permeability of subsurface materials affects the flow rate and the permeability of geologic materials is highly variable. Using passive samplers in a flow-through cell, the flow rate may not need to be known exactly, as long as it is sufficient to purge the cell in a reasonable time and minimize any negative bias attributable to the starvation effect. An experiment was performed in a 500 mL flow-through cell using a two-factor, one-half fraction fractional factorial test design with flow rates of 80, 670 and 930 mL min(-1) and sample durations of 10, 15 and 20 minutes for each of five different passive samplers (passive Automatic Thermal Desorption Tube, Radiello®, SKC Ultra, Waterloo Membrane Sampler™ and 3M™ OVM 3500). A Summa canister was collected coincident with each passive sampler and analyzed by EPA Method TO-15 to provide a baseline for comparison of the passive sampler concentrations. The passive sampler concentrations were within a factor of 2 of the Summa canister concentrations in 32 of 35 cases. Passive samples collected at the low flow rate and short duration showed low concentrations, which is likely attributable to insufficient purging of the cell after sampler placement.

Experimental Studies of the Interaction Between a Parallel Shear Flow and a Directionally-Solidifying Front

NASA Technical Reports Server (NTRS)

Zhang, Meng; Maxworthy, Tony

1999-01-01

It has long been recognized that flow in the melt can have a profound influence on the dynamics of a solidifying interface and hence the quality of the solid material. In particular, flow affects the heat and mass transfer, and causes spatial and temporal variations in the flow and melt composition. This results in a crystal with nonuniform physical properties. Flow can be generated by buoyancy, expansion or contraction upon phase change, and thermo-soluto capillary effects. In general, these flows can not be avoided and can have an adverse effect on the stability of the crystal structures. This motivates crystal growth experiments in a microgravity environment, where buoyancy-driven convection is significantly suppressed. However, transient accelerations (g-jitter) caused by the acceleration of the spacecraft can affect the melt, while convection generated from the effects other than buoyancy remain important. Rather than bemoan the presence of convection as a source of interfacial instability, Hurle in the 1960s suggested that flow in the melt, either forced or natural convection, might be used to stabilize the interface. Delves considered the imposition of both a parabolic velocity profile and a Blasius boundary layer flow over the interface. He concluded that fast stirring could stabilize the interface to perturbations whose wave vector is in the direction of the fluid velocity. Forth and Wheeler considered the effect of the asymptotic suction boundary layer profile. They showed that the effect of the shear flow was to generate travelling waves parallel to the flow with a speed proportional to the Reynolds number. There have been few quantitative, experimental works reporting on the coupling effect of fluid flow and morphological instabilities. Huang studied plane Couette flow over cells and dendrites. It was found that this flow could greatly enhance the planar stability and even induce the cell-planar transition. A rotating impeller was buried inside the

Magnetic fingerprints of rolling cells for quantitative flow cytometry in whole blood

NASA Astrophysics Data System (ADS)

Reisbeck, Mathias; Helou, Michael Johannes; Richter, Lukas; Kappes, Barbara; Friedrich, Oliver; Hayden, Oliver

2016-09-01

Over the past 50 years, flow cytometry has had a profound impact on preclinical and clinical applications requiring single cell function information for counting, sub-typing and quantification of epitope expression. At the same time, the workflow complexity and high costs of such optical systems still limit flow cytometry applications to specialized laboratories. Here, we present a quantitative magnetic flow cytometer that incorporates in situ magnetophoretic cell focusing for highly accurate and reproducible rolling of the cellular targets over giant magnetoresistance sensing elements. Time-of-flight analysis is used to unveil quantitative single cell information contained in its magnetic fingerprint. Furthermore, we used erythrocytes as a biological model to validate our methodology with respect to precise analysis of the hydrodynamic cell diameter, quantification of binding capacity of immunomagnetic labels, and discrimination of cell morphology. The extracted time-of-flight information should enable point-of-care quantitative flow cytometry in whole blood for clinical applications, such as immunology and primary hemostasis.

Non-Flow-Through Fuel Cell System Test Results and Demonstration on the SCARAB Rover

NASA Technical Reports Server (NTRS)

Scheidegger, Brianne; Burke, Kenneth; Jakupca, Ian

2012-01-01

This presentation describes the results of the demonstration of a non-flow-through PEM fuel cell as part of a power system on the SCARAB rover at the NASA Glenn Research Center. A 16-cell non-flow-through fuel cell stack from Infinity Fuel Cell and Hydrogen, Inc. was incorporated into a power system designed to act as a range extender by providing power to the SCARAB rover s hotel loads. The power system, including the non-flow-through fuel cell technology, successfully demonstrated its goal as a range extender by powering hotel loads on the SCARAB rover, making this demonstration the first to use the non-flow-through fuel cell technology on a mobile platform.

Fluid flow plate for decreased density of fuel cell assembly

DOEpatents

Vitale, Nicholas G.

1999-01-01

A fluid flow plate includes first and second outward faces. Each of the outward faces has a flow channel thereon for carrying respective fluid. At least one of the fluids serves as reactant fluid for a fuel cell of a fuel cell assembly. One or more pockets are formed between the first and second outward faces for decreasing density of the fluid flow plate. A given flow channel can include one or more end sections and an intermediate section. An interposed member can be positioned between the outward faces at an interface between an intermediate section, of one of the outward faces, and an end section, of that outward face. The interposed member can serve to isolate the reactant fluid from the opposing outward face. The intermediate section(s) of flow channel(s) on an outward face are preferably formed as a folded expanse.

Webcam-based flow cytometer using wide-field imaging for low cell number detection at high throughput.

PubMed

Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

2014-09-07

Here we describe a novel low-cost flow cytometer based on a webcam capable of low cell number detection in a large volume which may overcome the limitations of current flow cytometry. Several key elements have been combined to yield both high throughput and high sensitivity. The first element is a commercially available webcam capable of 187 frames per second video capture at a resolution of 320 × 240 pixels. The second element in this design is a 1 W 450 nm laser module for area-excitation, which combined with the webcam allows for rapid interrogation of a flow field. The final element is a 2D flow-cell which overcomes the flow limitation of hydrodynamic focusing and allows for higher sample throughput in a wider flow field. This cell allows for the linear velocity of target cells to be lower than in a conventional "1D" hydrodynamic focusing flow-cells typically used in cytometry at similar volumetric flow rates. It also allows cells to be imaged at the full frame rate of the webcam. Using this webcam-based flow cytometer with wide-field imaging, it was confirmed that the detection of fluorescently tagged 5 μm polystyrene beads in "1D" hydrodynamic focusing flow-cells was not practical for low cell number detection due to streaking from the motion of the beads, which did not occur with the 2D flow-cell design. The sensitivity and throughput of this webcam-based flow cytometer was then investigated using THP-1 human monocytes stained with SYTO-9 florescent dye in the 2D flow-cell. The flow cytometer was found to be capable of detecting fluorescently tagged cells at concentrations as low as 1 cell per mL at flow rates of 500 μL min(-1) in buffer and in blood. The effectiveness of detection was concentration dependent: at 100 cells per mL 84% of the cells were detected compared to microscopy, 10 cells per mL 79% detected and 1 cell per mL 59% of the cells were detected. With the blood samples spiked to 100 cells per mL, the average concentration for all samples

Quantitative flow visualization applied to wake flow studies

NASA Astrophysics Data System (ADS)

Rukweza, Godfrey

An experimental study of the flow past stationary cylinders of circular, triangular and rectangular cross-section in cross-flow has been made using three different techniques. These are hot-film anemometry, smoke-wire flow visualization, and particle image velocimetry. The point measurement technique of constant temperature hot-film anemometry was used to confirm the findings of earlier investigations on the performance of cylinders with rectangular and triangular cross-sections. The thesis presents distributions of the mean streamwise velocity, fluctuation levels and spectra in the Reynolds number range 200 < Re[D] < 2.2 x 10[4]. Variations of the vortex shedding frequency with Reynolds number within the near-wake region are shown and related to the flow patterns obtained using the technique of smoke-wire flow visualisation. Finally, PIV was applied in a water channel to determine wake flow properties created by a circular cylinder at three Reynolds numbers of 200, 300 and 2.2 x 10[4]. For the PIV investigation, a technique was developed which enables a continuous wave laser beam to be pulsed using a Bragg cell : this system can be used to produce pulses of light which are separated by a specified time interval which is typically in the range 10[-4] to 10[-2] s. This was successfully used in the implementation of PIV in the highest Reynolds number conditions for which standard video frame rates of 25 fps are inadequate. In this relatively high speed flow, a novel technique was also developed for sampling the image data of seeding particles at a fixed phase. This enabled the phase-averaging of data derived by analysis of PIV system output with a good degree of success. Analysis of the flow image data was then performed using a customized PIV software package developed in the Department, in conjunction with a special purpose software package QFV. Results are presented for both the instantaneous and the phase-averaged distributions of velocity, vorticity, and shear

Perfusion flow bioreactor for 3D in situ imaging: investigating cell/biomaterials interactions.

PubMed

Stephens, J S; Cooper, J A; Phelan, F R; Dunkers, J P

2007-07-01

The capability to image real time cell/material interactions in a three-dimensional (3D) culture environment will aid in the advancement of tissue engineering. This paper describes a perfusion flow bioreactor designed to hold tissue engineering scaffolds and allow for in situ imaging using an upright microscope. The bioreactor can hold a scaffold of desirable thickness for implantation (>2 mm). Coupling 3D culture and perfusion flow leads to the creation of a more biomimetic environment. We examined the ability of the bioreactor to maintain cell viability outside of an incubator environment (temperature and pH stability), investigated the flow features of the system (flow induced shear stress), and determined the image quality in order to perform time-lapsed imaging of two-dimensional (2D) and 3D cell culture. In situ imaging was performed on 2D and 3D, culture samples and cell viability was measured under perfusion flow (2.5 mL/min, 0.016 Pa). The visualization of cell response to their environment, in real time, will help to further elucidate the influences of biomaterial surface features, scaffold architectures, and the influence of flow induced shear on cell response and growth of new tissue. (c) 2006 Wiley Periodicals, Inc.

Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels

PubMed Central

Lee, Pil Hyong; Hwang, Sang Soon

2009-01-01

In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, with simple micro parallel flow channels. It is known that the humidity at the cathode flow channel becomes very important for enhancing the ion conductivity of polymer membrane because fully humidified condition was normally set at anode. To investigate the effect of humidity on the performance of a fuel cell, in this study humidification was set to 100% at the anode flow channel and was changed by 0–100% at the cathode flow channel. Results showed that the maximum power density could be obtained under 60% humidified condition at the cathode where oxygen concentration was moderately high while maintaining high ion conductivity at a membrane. PMID:22291556

Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels.

PubMed

Lee, Pil Hyong; Hwang, Sang Soon

2009-01-01

In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, with simple micro parallel flow channels. It is known that the humidity at the cathode flow channel becomes very important for enhancing the ion conductivity of polymer membrane because fully humidified condition was normally set at anode. To investigate the effect of humidity on the performance of a fuel cell, in this study humidification was set to 100% at the anode flow channel and was changed by 0-100% at the cathode flow channel. Results showed that the maximum power density could be obtained under 60% humidified condition at the cathode where oxygen concentration was moderately high while maintaining high ion conductivity at a membrane.

Continuous flow electrophoretic separation of proteins and cells from mammalian tissues

NASA Technical Reports Server (NTRS)

Hymer, W. C.; Barlow, Grant H.; Blaisdell, Steven J.; Cleveland, Carolyn; Farrington, Mary Ann; Feldmeier, Mary; Hatfield, J. Michael; Lanham, J. Wayne; Grindeland, Richard; Snyder, Robert S.

1987-01-01

This paper describes an apparatus for continuous flow electrophoresis (CFE), designed to separate macromolecules and cells at conditions of microgravity. In this CFE, buffer flows upward in a 120-cm long flow chamber, which is 16-cm wide x 3.0-mm thick in the microgravity version (and 6-cm wide x 1.5-mm thick in the unit-gravity laboratory version). Ovalbumin and rat serum albumin were separated in space (flight STS-4) with the same resolution of the two proteins achieved at 25 percent total w/v concentration that was obtained in the laboratory at 0.2 percent w/v concentration. Rat anterior pituitary cells, cultured human embryonic kidney cells, and canine Langerhans cells were separated into subpopulations (flight STS-8) more effectively than in unit gravity, with comparable resolution having been achieved at 100 times the concentration possible on earth.

Novel Quantitative Autophagy Analysis by Organelle Flow Cytometry after Cell Sonication

PubMed Central

Degtyarev, Michael; Reichelt, Mike; Lin, Kui

2014-01-01

Autophagy is a dynamic process of bulk degradation of cellular proteins and organelles in lysosomes. Current methods of autophagy measurement include microscopy-based counting of autophagic vacuoles (AVs) in cells. We have developed a novel method to quantitatively analyze individual AVs using flow cytometry. This method, OFACS (organelle flow after cell sonication), takes advantage of efficient cell disruption with a brief sonication, generating cell homogenates with fluorescently labeled AVs that retain their integrity as confirmed with light and electron microscopy analysis. These AVs could be detected directly in the sonicated cell homogenates on a flow cytometer as a distinct population of expected organelle size on a cytometry plot. Treatment of cells with inhibitors of autophagic flux, such as chloroquine or lysosomal protease inhibitors, increased the number of particles in this population under autophagy inducing conditions, while inhibition of autophagy induction with 3-methyladenine or knockdown of ATG proteins prevented this accumulation. This assay can be easily performed in a high-throughput format and opens up previously unexplored avenues for autophagy analysis. PMID:24489953

Flow cytometric techniques for detection of candidate cancer stem cell subpopulations in canine tumour models.

PubMed

Blacking, T M; Waterfall, M; Samuel, K; Argyle, D J

2012-12-01

The cancer stem cell (CSC) hypothesis proposes that tumour growth is maintained by a distinct subpopulation of 'CSC'. This study applied flow cytometric methods, reported to detect CSC in both primary and cultured cancer cells of other species, to identify candidate canine subpopulations. Cell lines representing diverse canine malignancies, and cells derived from spontaneous canine tumours, were evaluated for expression of stem cell-associated surface markers (CD34, CD44, CD117 and CD133) and functional properties [Hoecsht 33342 efflux, aldehyde dehydrogenase (ALDH) activity]. No discrete marker-defined subsets were identified within established cell lines; cells derived directly from spontaneous tumours demonstrated more heterogeneity, although this diminished upon in vitro culture. Functional assays produced variable results, suggesting context-dependency. Flow cytometric methods may be adopted to identify putative canine CSC. Whilst cell lines are valuable in assay development, primary cells may provide a more rewarding model for studying tumour heterogeneity in the context of CSC. However, it will be essential to fully characterize any candidate subpopulations to ensure that they meet CSC criteria. © 2011 Blackwell Publishing Ltd.

Structures, Compositions, and Activities of Live Shewanella Biofilms Formed on Graphite Electrodes in Electrochemical Flow Cells

PubMed Central

Kitayama, Miho; Koga, Ryota; Kasai, Takuya; Kouzuma, Atsushi

2017-01-01

ABSTRACT An electrochemical flow cell equipped with a graphite working electrode (WE) at the bottom was inoculated with Shewanella oneidensis MR-1 expressing an anaerobic fluorescent protein, and biofilm formation on the WE was observed over time during current generation at WE potentials of +0.4 and 0 V (versus standard hydrogen electrodes), under electrolyte-flow conditions. Electrochemical analyses suggested the presence of unique electron-transfer mechanisms in the +0.4-V biofilm. Microscopic analyses revealed that, in contrast to aerobic biofilms, current-generating biofilm (at +0.4 V) was thin and flat (∼10 μm in thickness), and cells were evenly and densely distributed in the biofilm. In contrast, cells were unevenly distributed in biofilm formed at 0 V. In situ fluorescence staining and biofilm recovery experiments showed that the amounts of extracellular polysaccharides (EPSs) in the +0.4-V biofilm were much smaller than those in the aerobic and 0-V biofilms, suggesting that Shewanella cells suppress the production of EPSs at +0.4 V under flow conditions. We suggest that Shewanella cells perceive electrode potentials and modulate the structure and composition of biofilms to efficiently transfer electrons to electrodes. IMPORTANCE A promising application of microbial fuel cells (MFCs) is to save energy in wastewater treatment. Since current is generated in these MFCs by biofilm microbes under horizontal flows of wastewater, it is important to understand the mechanisms for biofilm formation and current generation under water-flow conditions. Although massive work has been done to analyze the molecular mechanisms for current generation by model exoelectrogenic bacteria, such as Shewanella oneidensis, limited information is available regarding the formation of current-generating biofilms over time under water-flow conditions. The present study developed electrochemical flow cells and used them to examine the electrochemical and structural features of

Structures, Compositions, and Activities of Live Shewanella Biofilms Formed on Graphite Electrodes in Electrochemical Flow Cells.

PubMed

Kitayama, Miho; Koga, Ryota; Kasai, Takuya; Kouzuma, Atsushi; Watanabe, Kazuya

2017-09-01

An electrochemical flow cell equipped with a graphite working electrode (WE) at the bottom was inoculated with Shewanella oneidensis MR-1 expressing an anaerobic fluorescent protein, and biofilm formation on the WE was observed over time during current generation at WE potentials of +0.4 and 0 V (versus standard hydrogen electrodes), under electrolyte-flow conditions. Electrochemical analyses suggested the presence of unique electron-transfer mechanisms in the +0.4-V biofilm. Microscopic analyses revealed that, in contrast to aerobic biofilms, current-generating biofilm (at +0.4 V) was thin and flat (∼10 μm in thickness), and cells were evenly and densely distributed in the biofilm. In contrast, cells were unevenly distributed in biofilm formed at 0 V. In situ fluorescence staining and biofilm recovery experiments showed that the amounts of extracellular polysaccharides (EPSs) in the +0.4-V biofilm were much smaller than those in the aerobic and 0-V biofilms, suggesting that Shewanella cells suppress the production of EPSs at +0.4 V under flow conditions. We suggest that Shewanella cells perceive electrode potentials and modulate the structure and composition of biofilms to efficiently transfer electrons to electrodes. IMPORTANCE A promising application of microbial fuel cells (MFCs) is to save energy in wastewater treatment. Since current is generated in these MFCs by biofilm microbes under horizontal flows of wastewater, it is important to understand the mechanisms for biofilm formation and current generation under water-flow conditions. Although massive work has been done to analyze the molecular mechanisms for current generation by model exoelectrogenic bacteria, such as Shewanella oneidensis , limited information is available regarding the formation of current-generating biofilms over time under water-flow conditions. The present study developed electrochemical flow cells and used them to examine the electrochemical and structural features of current

Studies on unsaturated flow in dual-scale fiber fabrics

NASA Astrophysics Data System (ADS)

Yan, Fei; Yan, Shilin; Li, Yongjing

2018-03-01

Fiber fabrics in liquid composite molding (LCM) can be recognized as a dual-scale structure. As sink theory developed, this unsaturated flow behavior has already been simulated successfully; however, most of simulated results based on a unit cell under ideal status, thus making results were not agreement with experiment. In this study, an experimental method to establish sink function was proposed. After compared the simulation results by this sink function, it shows high accuracy with the experimental data. Subsequently, the key influencing factors for unsaturated flow have been further investigated; results show that the filling time for unsaturated flow was much longer than saturated flow. In addition, the injection pressure and permeability were the key factors lead to unsaturated flow.

Flow cytometric analyses of CD34+ cells with inclusion of internal positive controls.

PubMed

Gutensohn, Kai; Jessen, Maria; Ketels, Andrea; Gramatzki, Martin; Humpe, Andreas

2012-02-01

Flow cytometric measurement of CD34+ events is used to ensure the quality of human progenitor cell grafts. This study was conducted to evaluate whether the spiking of routine samples from peripheral blood and apheresis products with CD34+ positive controls is feasible. A total of 42 samples from 32 patients and one healthy donor were stained in duplicate for CD34+ cells. Before flow cytometric analysis, one tube was spiked with stabilized CD34+ cells at a defined concentration. Median numbers of viable CD34+ cells/µL did not differ between unspiked and spiked tubes (median 37, range 0-714; and median 34, range 0-719, respectively). The 95% confidence interval (CI) of the mean showed a broad overlap between these samples (41.9-119.1 and 41.4-119.3, respectively). In addition, the 95% CI of the mean for CD45+ cells/µL overlapped broadly and median numbers did not differ. Median viability of all CD45+ cells was significantly lower in the spiked tubes (96.75, range 64-98.8 vs. 99.25, range 97.5-99.8) with no overlap of the 95% CI of the mean viability. The results of this study show that spiking of routine samples with internal positive controls does not affect CD34+ cell analyses, but does support the reliability of important clinical data. The inclusion of positive controls is expedient for laboratories that perform analyses with low CD34+ numbers and laboratories that use different flow cytometric analyzers and may also become a requirement to meet statutory regulations. © 2012 American Association of Blood Banks.

Nanowell-Trapped Charged Ligand-Bearing Nanoparticle Surfaces – A Novel Method of Enhancing Flow-Resistant Cell Adhesion

PubMed Central

Tran, Phat L.; Gamboa, Jessica R.; McCracken, Katherine E.; Riley, Mark R.

2014-01-01

Assuring cell adhesion to an underlying biomaterial surface is vital in implant device design and tissue engineering, particularly under circumstances where cells are subjected to potential detachment from overriding fluid flow. Cell-substrate adhesion is a highly regulated process involving the interplay of mechanical properties, surface topographic features, electrostatic charge, and biochemical mechanisms. At the nanoscale level the physical properties of the underlying substrate are of particular importance in cell adhesion. Conventionally, natural, pro-adhesive, and often thrombogenic, protein biomaterials are frequently utilized to facilitate adhesion. In the present study nanofabrication techniques are utilized to enhance the biological functionality of a synthetic polymer surface, polymethymethacrylate, with respect to cell adhesion. Specifically we examine the effect on cell adhesion of combining: 1. optimized surface texturing, 2. electrostatic charge and 3. cell adhesive ligands, uniquely assembled on the substrata surface, as an ensemble of nanoparticles trapped in nanowells. Our results reveal that the ensemble strategy leads to enhanced, more than simply additive, endothelial cell adhesion under both static and flow conditions. This strategy may be of particular utility for enhancing flow-resistant endothelialization of blood-contacting surfaces of cardiovascular devices subjected to flow-mediated shear. PMID:23225491

Membrane water-flow rate in electrolyzer cells with a solid polymer electrolyte (SPE)

NASA Astrophysics Data System (ADS)

Li, Xiaojin; Qu, Shuguo; Yu, Hongmei; Hou, Ming; Shao, Zhigang; Yi, Baolian

Water-flow rate across Nafion membrane in SPE electrolyzer cells was measured and modelled. From the analysis of water transport mechanisms in SPE water electrolysis, the water-flow rate through membrane can be described by the electro-osmotic drag. The calculated electro-osmotic drag coefficients, n d, for the membrane in SPE electrolysis cells at different temperatures were compared with literature and in good agreement with those of Ge et al. and Ise et al. To describe the water-flow rate through membrane more accurately, a linear fit of n d as a function of temperature for the membrane in SPE water electrolysis was proposed in this paper. This paper studied the membrane water-flow rate experimentally and mathematically, which is of importance in the designing and optimization of the process of SPE water electrolysis. This paper also provided a novel method for measuring the electro-osmotic drag coefficient of Nafion membrane in contact with liquid water, acid and methanol solutions, etc.

Integrated Microfluidic Flow-Through Microbial Fuel Cells

PubMed Central

Jiang, Huawei; Ali, Md. Azahar; Xu, Zhen; Halverson, Larry J.; Dong, Liang

2017-01-01

This paper reports on a miniaturized microbial fuel cell with a microfluidic flow-through configuration: a porous anolyte chamber is formed by filling a microfluidic chamber with three-dimensional graphene foam as anode, allowing nutritional medium to flow through the chamber to intimately interact with the colonized microbes on the scaffolds of the anode. No nutritional media flow over the anode. This allows sustaining high levels of nutrient utilization, minimizing consumption of nutritional substrates, and reducing response time of electricity generation owing to fast mass transport through pressure-driven flow and rapid diffusion of nutrients within the anode. The device provides a volume power density of 745 μW/cm3 and a surface power density of 89.4 μW/cm2 using Shewanella oneidensis as a model biocatalyst without any optimization of bacterial culture. The medium consumption and the response time of the flow-through device are reduced by 16.4 times and 4.2 times, respectively, compared to the non-flow-through counterpart with its freeway space volume six times the volume of graphene foam anode. The graphene foam enabled microfluidic flow-through approach will allow efficient microbial conversion of carbon-containing bioconvertible substrates to electricity with smaller space, less medium consumption, and shorter start-up time. PMID:28120875

Integrated Microfluidic Flow-Through Microbial Fuel Cells

NASA Astrophysics Data System (ADS)

Jiang, Huawei; Ali, Md. Azahar; Xu, Zhen; Halverson, Larry J.; Dong, Liang

2017-01-01

This paper reports on a miniaturized microbial fuel cell with a microfluidic flow-through configuration: a porous anolyte chamber is formed by filling a microfluidic chamber with three-dimensional graphene foam as anode, allowing nutritional medium to flow through the chamber to intimately interact with the colonized microbes on the scaffolds of the anode. No nutritional media flow over the anode. This allows sustaining high levels of nutrient utilization, minimizing consumption of nutritional substrates, and reducing response time of electricity generation owing to fast mass transport through pressure-driven flow and rapid diffusion of nutrients within the anode. The device provides a volume power density of 745 μW/cm3 and a surface power density of 89.4 μW/cm2 using Shewanella oneidensis as a model biocatalyst without any optimization of bacterial culture. The medium consumption and the response time of the flow-through device are reduced by 16.4 times and 4.2 times, respectively, compared to the non-flow-through counterpart with its freeway space volume six times the volume of graphene foam anode. The graphene foam enabled microfluidic flow-through approach will allow efficient microbial conversion of carbon-containing bioconvertible substrates to electricity with smaller space, less medium consumption, and shorter start-up time.

Multi-Cellular 3D Human Primary Liver Cell Cultures Elevate Metabolic Activity Under Fluidic Flow

PubMed Central

Esch, Mandy B.; Prot, Jean-Matthieu; Wang, Ying I.; Miller, Paula; Llamas-Vidales, Jose Ricardo; Naughton, Brian A.; Applegate, Dawn R.

2015-01-01

Predicting drug-induced liver injury with in vitro cell culture models more accurately would be of significant value to the pharmaceutical industry. To this end we have developed a low-cost liver cell culture device that creates fluidic flow over a 3D primary liver cell culture that consists of multiple liver cell types, including hepatocytes and non-parenchymal cells (fibroblasts, stellate cells, and Kupffer cells). We tested the performance of the cell culture under fluidic flow for 14 days, finding that hepatocytes produced albumin and urea at elevated levels compared to static cultures. Hepatocytes also responded with induction of P450 (CYP1A1 and CYP3A4) enzyme activity when challenged with P450 inducers, although we did not find significant differences between static and fluidic cultures. Non-parenchymal cells were similarly responsive, producing interleukin 8 (IL-8) when challenged with 10 μM bacterial lipoprotein (LPS). To create the fluidic flow in an inexpensive manner, we used a rocking platform that tilts the cell culture devices at angles between ±12°, resulting in a periodically changing hydrostatic pressure drop and bidirectional fluid flow (average flow rate of 650 μL/min, and a maximum shear stress of 0.64 dyne/cm2). The increase in metabolic activity is consistent with the hypothesis that, similar to unidirectional fluidic flow, primary liver cell cultures derived from human tissues increase their metabolic activity in response to bidirectional fluidic flow. Since bidirectional flow drastically changes the behavior of other cells types that are shear sensitive, the finding that bidirectional flow increases the metabolic activity of primary liver cells also supports the theory that this increase in metabolic activity is likely caused by increased levels of gas and metabolite exchange or by the accumulation of soluble growth factors rather than by shear sensing. Our results indicate that device operation with bi-directional gravity-driven medium

Design and fabrication of novel anode flow-field for commercial size solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Canavar, Murat; Timurkutluk, Bora

2017-04-01

In this study, nickel based woven meshes are tested as not only anode current collecting meshes but also anode flow fields instead of the conventional gas channels fabricated by machining. For this purpose, short stacks with different anode flow fields are designed and built by using different number of meshes with various wire diameters and widths of opening. A short stack with classical machined flow channels is also constructed. Performance and impedance measurements of the short stacks with commercial size cells of 81 cm2 active area are performed and compared. The results reveal that it is possible to create solid oxide fuel cell anode flow fields with woven meshes and obtain acceptable power with a proper selection of the mesh number, type and orientation.

Gαq/11-mediated intracellular calcium responses to retrograde flow in endothelial cells.

PubMed

Melchior, Benoît; Frangos, John A

2012-08-15

Disturbed flow patterns, including reversal in flow direction, are key factors in the development of dysfunctional endothelial cells (ECs) and atherosclerotic lesions. An almost immediate response of ECs to fluid shear stress is the increase in cytosolic calcium concentration ([Ca(2+)](i)). Whether the source of [Ca(2+)](i) is extracellular, released from Ca(2+) intracellular stores, or both is still undefined, though it is likely dependent on the nature of forces involved. We have previously shown that a change in flow direction (retrograde flow) on a flow-adapted endothelial monolayer induces the remodeling of the cell-cell junction along with a dramatic [Ca(2+)](i) burst compared with cells exposed to unidirectional or orthograde flow. The heterotrimeric G protein-α q and 11 subunit (Gα(q/11)) is a likely candidate in effecting shear-induced increases in [Ca(2+)](i) since its expression is enriched at the junction and has been previously shown to be activated within seconds after onset of flow. In flow-adapted human ECs, we have investigated to what extent the Gα(q/11) pathway mediates calcium dynamics after reversal in flow direction. We observed that the elapsed time to peak [Ca(2+)](i) response to a 10 dyn/cm(2) retrograde shear stress was increased by 11 s in cells silenced with small interfering RNA directed against Gα(q/11). A similar lag in [Ca(2+)](i) transient was observed after cells were treated with the phospholipase C (PLC)-βγ inhibitor, U-73122, or the phosphatidylinositol-specific PLC inhibitor, edelfosine, compared with controls. Lower levels of inositol 1,4,5-trisphosphate accumulation seconds after the onset of flow correlated with the increased lag in [Ca(2+)](i) responses observed with the different treatments. In addition, inhibition of the inositol 1,4,5-trisphosphate receptor entirely abrogated flow-induced [Ca(2+)](i). Taken together, our results identify the Gα(q/11)-PLC pathway as the initial trigger for retrograde flow

Effects of flow configuration on bone tissue engineering using human mesenchymal stem cells in 3D chitosan composite scaffolds.

PubMed

Sellgren, Katelyn L; Ma, Teng

2015-08-01

Perfusion bioreactor plays important role in supporting 3D bone construct development. Scaffolds of chitosan composites have been studied to support bone tissue regeneration from osteogenic progenitor cells including human mesenchymal stem cells (hMSC). In this study, porous scaffolds of hydroxyapatite (H), chitosan (C), and gelatin (G) were fabricated by phase-separation and press-fitted in the perfusion bioreactor system where media flow is configured either parallel or transverse with respect to the scaffolds to investigate the impact of flow configuration on hMSC proliferation and osteogenic differentiation. The in vitro results showed that the interstitial flow in the transverse flow (TF) constructs reduced cell growth during the first week of culture but improved spatial cell distribution and early onset of osteogenic differentiation measured by alkaline phosphatase and expression of osteogenic genes. After 14 days of bioreactor culture, the TF constructs have comparable cell number but higher expression of bone markers genes and proteins compared to the parallel flow constructs. To evaluate ectopic bone formation, the HCG constructs seeded with hMSCs pre-cultured under two flow configurations for 7 days were implanted in CD-1 nude mice. While Masson's Trichrom staining revealed bone formation in both constructs, the TF constructs have improved spatial cell and osteoid distribution throughout the 2.0 mm constructs. The results highlight the divergent effects of media flow over the course of construct development and suggest that the flow configuration is an important parameter regulating the cellular events leading to bone construct formation in the HCG scaffolds. © 2014 Wiley Periodicals, Inc.

Flow Line, Durafill VS, and Dycal toxicity to dental pulp cells: effects of growth factors

PubMed Central

Furey, Alyssa; Hjelmhaug, Julie; Lobner, Doug

2010-01-01

Introduction The objective was to determine the effects of growth factor treatment on dental pulp cell sensitivity to toxicity of two composite restoration materials, Flow Line and Durafill VS, and a calcium hydroxide pulp capping material, Dycal. Methods Toxicity of the dental materials to cultures of primary dental pulp cells was determined by the MTT metabolism assay. The ability of six different growth factors to influence the toxicity was tested. Results A 24 hour exposure to either Flow Line or Durafill VS caused approximately 40% cell death, while Dycal exposure caused approximately 80% cell death. The toxicity of Flow Line and Durafill VS was mediated by oxidative stress. Four of the growth factors tested (BMP-2, BMP-7, EGF, and TGF-β) decreased the basal MTT values while making the cells resistant to Flow Line and Durafill VS toxicity, except BMP-2 which made the cells more sensitive to Flow Line. Treatment with FGF-2 caused no change in basal MTT metabolism, prevented the toxicity of Durafill VS, but increased the toxicity of Flow Line. Treatment with IGF-I increased basal MTT metabolism and made the cells resistant to Flow Line and Durafill VS toxicity. None of the growth factors made the cells resistant to Dycal toxicity. Conclusions The results indicate that growth factors can be used to alter the sensitivity of dental pulp cells to commonly used restoration materials. The growth factors BMP-7, EGF, TGF-β, and IGF-I provided the best profile of effects, making the cells resistant to both Flow Line and Durafill VS toxicity. PMID:20630288

Redox flow cell development and demonstration project, calendar year 1977

NASA Technical Reports Server (NTRS)

1979-01-01

Research and development on the redox flow cell conducted from January 1, 1977, to December 31, 1977, are described in this report. The major focus of the effort during 1977 was the key technology issues that directly influence the fundamental feasibility of the overall redox concept. These issues were the development of a suitable ion exchange membrane for the system, the screening and study of candidate redox couples to achieve optimum cell performance, and the carrying out of systems analysis and modeling to develop system performance goals and cost estimates.

Well-balanced compressible cut-cell simulation of atmospheric flow.

PubMed

Klein, R; Bates, K R; Nikiforakis, N

2009-11-28

Cut-cell meshes present an attractive alternative to terrain-following coordinates for the representation of topography within atmospheric flow simulations, particularly in regions of steep topographic gradients. In this paper, we present an explicit two-dimensional method for the numerical solution on such meshes of atmospheric flow equations including gravitational sources. This method is fully conservative and allows for time steps determined by the regular grid spacing, avoiding potential stability issues due to arbitrarily small boundary cells. We believe that the scheme is unique in that it is developed within a dimensionally split framework, in which each coordinate direction in the flow is solved independently at each time step. Other notable features of the scheme are: (i) its conceptual and practical simplicity, (ii) its flexibility with regard to the one-dimensional flux approximation scheme employed, and (iii) the well-balancing of the gravitational sources allowing for stable simulation of near-hydrostatic flows. The presented method is applied to a selection of test problems including buoyant bubble rise interacting with geometry and lee-wave generation due to topography.

Accurate live and dead bacterial cell enumeration using flow cytometry (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ou, Fang; McGoverin, Cushla; Swift, Simon; Vanholsbeeck, Frédérique

2017-03-01

Flow cytometry (FCM) is based on the detection of scattered light and fluorescence to identify cells with particular characteristics of interest. However most FCM cannot precisely control the flow through its interrogation point and hence the volume and concentration of the sample cannot be immediately obtained. The easiest, most reliable and inexpensive way of obtaining absolute counts with FCM is by using reference beads. We investigated a method of using FCM with reference beads to measure live and dead bacterial concentration over the range of 106 to 108 cells/mL and ratio varying from 0 to 100%. We believe we are the first to use this method for such a large cell concentration range while also establishing the effect of varying the live/dead bacteria ratios. Escherichia coli solutions with differing ratios of live:dead cells were stained with fluorescent dyes SYTO 9 and propidium iodide (PI), which label live and dead cells, respectively. Samples were measured using a LSR II Flow Cytometer (BD Biosciences); using 488 nm excitation with 20 mW power. Both SYTO 9 and PI fluorescence were collected and threshold was set to side scatter. Traditional culture-based plate count was done in parallel to the FCM analysis. The concentration of live bacteria from FCM was compared to that obtained by plate counts. Preliminary results show that the concentration of live bacteria obtained by FCM and plate counts correlate well with each other and indicates this may be extended to a wider concentration range or for studying other cell characteristics.

Cut-cell method based large-eddy simulation of tip-leakage flow

NASA Astrophysics Data System (ADS)

Pogorelov, Alexej; Meinke, Matthias; Schröder, Wolfgang

2015-07-01

The turbulent low Mach number flow through an axial fan at a Reynolds number of 9.36 × 105 based on the outer casing diameter is investigated by large-eddy simulation. A finite-volume flow solver in an unstructured hierarchical Cartesian setup for the compressible Navier-Stokes equations is used. To account for sharp edges, a fully conservative cut-cell approach is applied. A newly developed rotational periodic boundary condition for Cartesian meshes is introduced such that the simulations are performed just for a 72° segment, i.e., the flow field over one out of five axial blades is resolved. The focus of this numerical analysis is on the development of the vortical flow structures in the tip-gap region. A detailed grid convergence study is performed on four computational grids with 50 × 106, 250 × 106, 1 × 109, and 1.6 × 109 cells. Results of the instantaneous and the mean fan flow field are thoroughly analyzed based on the solution with 1 × 109 cells. High levels of turbulent kinetic energy and pressure fluctuations are generated by a tip-gap vortex upstream of the blade, the separating vortices inside the tip gap, and a counter-rotating vortex on the outer casing wall. An intermittent interaction of the turbulent wake, generated by the tip-gap vortex, with the downstream blade, leads to a cyclic transition with high pressure fluctuations on the suction side of the blade and a decay of the tip-gap vortex. The disturbance of the tip-gap vortex results in an unsteady behavior of the turbulent wake causing the intermittent interaction. For this interaction and the cyclic transition, two dominant frequencies are identified which perfectly match with the characteristic frequencies in the experimental sound power level and therefore explain their physical origin.

Experimental study of streaming flows associated with ultrasonic levitators

NASA Astrophysics Data System (ADS)

Trinh, E. H.; Robey, J. L.

1994-11-01

Steady-state acoustic streaming flow patterns have been observed during the operation of a variety of resonant single-axis ultrasonic levitators in a gaseous environment and in the 20-37 kHz frequency range. Light sheet illumination and scattering from smoke particles have revealed primary streaming flows which display different characteristics at low and high sound pressure levels. Secondary macroscopic streaming cells around levitated samples are superimposed on the primary streaming flow pattern generated by the standing wave. These recorded flows are quite reproducible, and are qualitatively the same for a variety of levitator physical geometries. An onset of flow instability can also be recorded in nonisothermal systems, such as levitated spot-heated samples when the resonance conditions are not exactly satisfied. A preliminary qualitative interpretation of these experimental results is presented in terms of the superposition of three discrete sets of circulation cells operating on different spatial scales. These relevant length scales are the acoustic wavelength, the levitated sample size, and finally the acoustic boundary layer thickness. This approach fails, however, to explain the streaming flow-field morphology around liquid drops levitated on Earth. Observation of the interaction between the flows cells and the levitated samples also suggests the existence of a steady-state torque induced by the streaming flows.

Multi-cellular 3D human primary liver cell culture elevates metabolic activity under fluidic flow.

PubMed

Esch, Mandy B; Prot, Jean-Matthieu; Wang, Ying I; Miller, Paula; Llamas-Vidales, Jose Ricardo; Naughton, Brian A; Applegate, Dawn R; Shuler, Michael L

2015-05-21

We have developed a low-cost liver cell culture device that creates fluidic flow over a 3D primary liver cell culture that consists of multiple liver cell types, including hepatocytes and non-parenchymal cells (fibroblasts, stellate cells, and Kupffer cells). We tested the performance of the cell culture under fluidic flow for 14 days, finding that hepatocytes produced albumin and urea at elevated levels compared to static cultures. Hepatocytes also responded with induction of P450 (CYP1A1 and CYP3A4) enzyme activity when challenged with P450 inducers, although we did not find significant differences between static and fluidic cultures. Non-parenchymal cells were similarly responsive, producing interleukin 8 (IL-8) when challenged with 10 μM bacterial lipoprotein (LPS). To create the fluidic flow in an inexpensive manner, we used a rocking platform that tilts the cell culture devices at angles between ±12°, resulting in a periodically changing hydrostatic pressure drop between reservoirs and the accompanying periodically changing fluidic flow (average flow rate of 650 μL min(-1), and a maximum shear stress of 0.64 dyne cm(-2)). The increase in metabolic activity is consistent with the hypothesis that, similar to unidirectional fluidic flow, primary liver cell cultures increase their metabolic activity in response to fluidic flow periodically changes direction. Since fluidic flow that changes direction periodically drastically changes the behavior of other cells types that are shear sensitive, our findings support the theory that the increase in hepatic metabolic activity associated with fluidic flow is either activated by mechanisms other than shear sensing (for example increased opportunities for gas and metabolite exchange), or that it follows a shear sensing mechanism that does not depend on the direction of shear. Our mode of device operation allows us to evaluate drugs under fluidic cell culture conditions and at low device manufacturing and operation

MRI studies of the hydrodynamics in a USP 4 dissolution testing cell.

PubMed

Shiko, G; Gladden, L F; Sederman, A J; Connolly, P C; Butler, J M

2011-03-01

We present a detailed study of hydrodynamics inside the flow-through dissolution apparatus when operated according to USP recommendations. The pulsatile flow inside the flow-through cell was measured quantitatively using magnetic resonance imaging (MRI) at a spatial resolution of 234 × 234 μm(2) and slice thickness of 1 mm. We report the experimental protocols developed for in situ MRI studies and the effect that the operating conditions and tablet orientation have on the hydrodynamics inside commercial flow cells. It was found that the flow field inside the dissolution cells was, at most operating conditions, heterogeneous, rather than fully developed laminar flow, and characterised by re-circulation and backward flow. A model tablet was shown to be contacted by a wide distribution of local velocities as a function of position and orientation in the flow cell. The use of 1 mm beads acted as a distributor of the flow but did not suffice to ensure a fully developed laminar flow profile. These results emphasise the necessity to understand the influence of test conditions on dissolution behaviour in defining robust flow-through dissolution methods. Copyright © 2010 Wiley-Liss, Inc.

Discovering cell types in flow cytometry data with random matrix theory

NASA Astrophysics Data System (ADS)

Shen, Yang; Nussenblatt, Robert; Losert, Wolfgang

Flow cytometry is a widely used experimental technique in immunology research. During the experiments, peripheral blood mononuclear cells (PBMC) from a single patient, labeled with multiple fluorescent stains that bind to different proteins, are illuminated by a laser. The intensity of each stain on a single cell is recorded and reflects the amount of protein expressed by that cell. The data analysis focuses on identifying specific cell types related to a disease. Different cell types can be identified by the type and amount of protein they express. To date, this has most often been done manually by labelling a protein as expressed or not while ignoring the amount of expression. Using a cross correlation matrix of stain intensities, which contains both information on the proteins expressed and their amount, has been largely ignored by researchers as it suffers from measurement noise. Here we present an algorithm to identify cell types in flow cytometry data which uses random matrix theory (RMT) to reduce noise in a cross correlation matrix. We demonstrate our method using a published flow cytometry data set. Compared with previous analysis techniques, we were able to rediscover relevant cell types in an automatic way. Department of Physics, University of Maryland, College Park, MD 20742.

Study of low speed flow cytometry for diffraction imaging with different chamber and nozzle designs.

PubMed

Sa, Yu; Feng, Yuanming; Jacobs, Kenneth M; Yang, Jun; Pan, Ran; Gkigkitzis, Ioannis; Lu, Jun Q; Hu, Xin-Hua

2013-11-01

Achieving effective hydrodynamic focusing and flow stability at low speed presents a challenging design task in flow cytometry for studying phenomena such as cell adhesion and diffraction imaging of cells with low-cost cameras. We have developed different designs of flow chamber and sheath nozzle to accomplish the above goal. A 3D computational model of the chambers has been established to simulate the fluid dynamics in different chamber designs and measurements have been performed to determine the velocity and size distributions of the core fluid from the nozzle. Comparison of the simulation data with experimental results shows good agreement. With the computational model significant insights were gained for optimization of the chamber design and improvement of the cell positioning accuracy for study of slow moving cells. The benefit of low flow speed has been demonstrated also by reduced blurring in the diffraction images of single cells. Based on these results, we concluded that the new designs of chamber and sheath nozzle produce stable hydrodynamic focusing of the core fluid at low speed and allow detailed study of cellular morphology under various rheological conditions using the diffraction imaging method. © 2013 International Society for Advancement of Cytometry.

Label-free counting of circulating cells by in vivo photoacoustic flow cytometry

NASA Astrophysics Data System (ADS)

Zhou, Quanyu; Yang, Ping; Wang, Qiyan; Pang, Kai; Zhou, Hui; He, Hao; Wei, Xunbin

2018-02-01

Melanoma, developing from melanocytes, is the most serious type of skin cancer. Circulating melanoma cells, the prognosis marker for metastasis, are present in the circulation at the early stage. Thus, quantitative detection of rare circulating melanoma cells is essential for monitoring tumor metastasis and prognosis evaluation. Compared with in vitro assays, in vivo flow cytometry is able to identify circulating tumor cells without drawing blood. Here, we built in vivo photoacoustic flow cytometry based on the high absorption coefficient of melanoma cells, which is applied to labelfree counting of circulating melanoma cells in tumor-bearing mice.

The Advantages of Non-Flow-Through Fuel Cell Power Systems for Aerospace Applications

NASA Technical Reports Server (NTRS)

Hoberecht, Mark; Burke, Kenneth; Jakupca, Ian

2011-01-01

NASA has been developing proton-exchange-membrane (PEM) fuel cell power systems for the past decade, as an upgraded technology to the alkaline fuel cells which presently provide power for the Shuttle Orbiter. All fuel cell power systems consist of one or more fuel cell stacks in combination with appropriate balance-of-plant hardware. Traditional PEM fuel cells are characterized as flow-through, in which recirculating reactant streams remove product water from the fuel cell stack. NASA recently embarked on the development of non-flow-through fuel cell systems, in which reactants are dead-ended into the fuel cell stack and product water is removed by internal wicks. This simplifies the fuel cell power system by eliminating the need for pumps to provide reactant circulation, and mechanical water separators to remove the product water from the recirculating reactant streams. By eliminating these mechanical components, the resulting fuel cell power system has lower mass, volume, and parasitic power requirements, along with higher reliability and longer life. These improved non-flow-through fuel cell power systems therefore offer significant advantages for many aerospace applications.

Classification of biological cells using a sound wave based flow cytometer

NASA Astrophysics Data System (ADS)

Strohm, Eric M.; Gnyawali, Vaskar; Van De Vondervoort, Mia; Daghighi, Yasaman; Tsai, Scott S. H.; Kolios, Michael C.

2016-03-01

A flow cytometer that uses sound waves to determine the size of biological cells is presented. In this system, a microfluidic device made of polydimethylsiloxane (PDMS) was developed to hydrodynamically flow focus cells in a single file through a target area. Integrated into the microfluidic device was an ultrasound transducer with a 375 MHz center frequency, aligned opposite the transducer was a pulsed 532 nm laser focused into the device by a 10x objective. Each passing cell was insonfied with a high frequency ultrasound pulse, and irradiated with the laser. The resulting ultrasound and photoacoustic waves from each cell were analyzed using signal processing methods, where features in the power spectra were compared to theoretical models to calculate the cell size. Two cell lines with different size distributions were used to test the system: acute myeloid leukemia cells (AML) and melanoma cells. Over 200 cells were measured using this system. The average calculated diameter of the AML cells was 10.4 +/- 2.5 μm using ultrasound, and 11.4 +/- 2.3 μm using photoacoustics. The average diameter of the melanoma cells was 16.2 +/- 2.9 μm using ultrasound, and 18.9 +/- 3.5 μm using photoacoustics. The cell sizes calculated using ultrasound and photoacoustic methods agreed with measurements using a Coulter Counter, where the AML cells were 9.8 +/- 1.8 μm and the melanoma cells were 16.0 +/- 2.5 μm. These results demonstrate a high speed method of assessing cell size using sound waves, which is an alternative method to traditional flow cytometry techniques.

Open-access and multi-directional electroosmotic flow chip for positioning heterotypic cells.

PubMed

Terao, Kyohei; Kitazawa, Yuko; Yokokawa, Ryuji; Okonogi, Atsuhito; Kotera, Hidetoshi

2011-04-21

We propose a novel method of cell positioning using electroosmotic flow (EOF) to analyze cell-cell interactions. The EOF chip has an open-to-air configuration, is equipped with four electrodes to induce multi-directional EOF, and allows access of tools for liquid handling and of physical probes for cell measurements. Evaluation of the flow within this chip indicated that it controlled hydrodynamic transport of cells, in terms of both speed and direction. We also evaluated cell viability after EOF application and determined appropriate conditions for cell positioning. Two cells were successively positioned in pocket-like microstructures, one in each micropocket, by controlling the EOF direction. As an experimental demonstration, we observed contact interactions between two individual cells through gap junction channels. The EOF chip should provide ways to elucidate various cell-cell interactions between heterotypic cells.

Microfluidic channel flow cell for simultaneous cryoelectrochemical electron spin resonance.

PubMed

Wain, Andrew J; Compton, Richard G; Le Roux, Rudolph; Matthews, Sinead; Fisher, Adrian C

2007-03-01

A novel microfluidic electrochemical channel flow cell has been constructed for in situ operation in a cylindrical TE011 resonant ESR cavity under variable temperature conditions. The cell has a U-tube configuration, consisting of an inlet and outlet channel which run parallel and contain evaporated gold film working, pseudo-reference, and counter electrodes. This geometry was employed to permit use in conjunction with variable temperature apparatus which does not allow a flow-through approach. The cell is characterized qualitatively and quantitatively using the one-electron reduction of p-bromonitrobenzene in acetonitrile at room temperature as a model system, and the ESR signal-flow rate response is validated by use of three-dimensional digital simulation of the concentration profile for a stable electrogenerated radical species under hydrodynamic conditions. The cell is then used to obtain ESR spectra for a number of radical species in acetonitrile at 233 K, including the radical anions of m- and p-iodonitrobenzene, o-bromonitrobenzene, and m-nitrobenzyl chloride, the latter three being unstable at room temperature. Spectra are also presented for the radical anion of 2-chloranthraquinone and the crystal violet radical, which display improved resolution at low temperatures.

Characterization of winemaking yeast by cell number-size distribution analysis through flow field-flow fractionation with multi-wavelength turbidimetric detection.

PubMed

Zattoni, Andrea; Melucci, Dora; Reschiglian, Pierluigi; Sanz, Ramsés; Puignou, Lluís; Galceran, Maria Teresa

2004-10-29

Yeasts are widely used in several areas of food industry, e.g. baking, beer brewing, and wine production. Interest in new analytical methods for quality control and characterization of yeast cells is thus increasing. The biophysical properties of yeast cells, among which cell size, are related to yeast cell capabilities to produce primary and secondary metabolites during the fermentation process. Biophysical properties of winemaking yeast strains can be screened by field-flow fractionation (FFF). In this work we present the use of flow FFF (FlFFF) with turbidimetric multi-wavelength detection for the number-size distribution analysis of different commercial winemaking yeast varieties. The use of a diode-array detector allows to apply to dispersed samples like yeast cells the recently developed method for number-size (or mass-size) analysis in flow-assisted separation techniques. Results for six commercial winemaking yeast strains are compared with data obtained by a standard method for cell sizing (Coulter counter). The method here proposed gives, at short analysis time, accurate information on the number of cells of a given size, and information on the total number of cells.

Separation of cancer cells from white blood cells by pinched flow fractionation.

PubMed

Pødenphant, Marie; Ashley, Neil; Koprowska, Kamila; Mir, Kalim U; Zalkovskij, Maksim; Bilenberg, Brian; Bodmer, Walter; Kristensen, Anders; Marie, Rodolphe

2015-12-21

In this paper, the microfluidic size-separation technique pinched flow fractionation (PFF) is used to separate cancer cells from white blood cells (WBCs). The cells are separated at efficiencies above 90% for both cell types. Circulating tumor cells (CTCs) are found in the blood of cancer patients and can form new tumors. CTCs are rare cells in blood, but they are important for the understanding of metastasis. There is therefore a high interest in developing a method for the enrichment of CTCs from blood samples, which also enables further analysis of the separated cells. The separation is challenged by the size overlap between cancer cells and the 10(6) times more abundant WBCs. The size overlap prevents high efficiency separation, however we demonstrate that cell deformability can be exploited in PFF devices to gain higher efficiencies than expected from the size distribution of the cells.

Wide-field Fluorescent Microscopy and Fluorescent Imaging Flow Cytometry on a Cell-phone

PubMed Central

Zhu, Hongying; Ozcan, Aydogan

2013-01-01

Fluorescent microscopy and flow cytometry are widely used tools in biomedical research and clinical diagnosis. However these devices are in general relatively bulky and costly, making them less effective in the resource limited settings. To potentially address these limitations, we have recently demonstrated the integration of wide-field fluorescent microscopy and imaging flow cytometry tools on cell-phones using compact, light-weight, and cost-effective opto-fluidic attachments. In our flow cytometry design, fluorescently labeled cells are flushed through a microfluidic channel that is positioned above the existing cell-phone camera unit. Battery powered light-emitting diodes (LEDs) are butt-coupled to the side of this microfluidic chip, which effectively acts as a multi-mode slab waveguide, where the excitation light is guided to uniformly excite the fluorescent targets. The cell-phone camera records a time lapse movie of the fluorescent cells flowing through the microfluidic channel, where the digital frames of this movie are processed to count the number of the labeled cells within the target solution of interest. Using a similar opto-fluidic design, we can also image these fluorescently labeled cells in static mode by e.g. sandwiching the fluorescent particles between two glass slides and capturing their fluorescent images using the cell-phone camera, which can achieve a spatial resolution of e.g. ~ 10 μm over a very large field-of-view of ~ 81 mm2. This cell-phone based fluorescent imaging flow cytometry and microscopy platform might be useful especially in resource limited settings, for e.g. counting of CD4+ T cells toward monitoring of HIV+ patients or for detection of water-borne parasites in drinking water. PMID:23603893

Wide-field fluorescent microscopy and fluorescent imaging flow cytometry on a cell-phone.

PubMed

Zhu, Hongying; Ozcan, Aydogan

2013-04-11

Fluorescent microscopy and flow cytometry are widely used tools in biomedical research and clinical diagnosis. However these devices are in general relatively bulky and costly, making them less effective in the resource limited settings. To potentially address these limitations, we have recently demonstrated the integration of wide-field fluorescent microscopy and imaging flow cytometry tools on cell-phones using compact, light-weight, and cost-effective opto-fluidic attachments. In our flow cytometry design, fluorescently labeled cells are flushed through a microfluidic channel that is positioned above the existing cell-phone camera unit. Battery powered light-emitting diodes (LEDs) are butt-coupled to the side of this microfluidic chip, which effectively acts as a multi-mode slab waveguide, where the excitation light is guided to uniformly excite the fluorescent targets. The cell-phone camera records a time lapse movie of the fluorescent cells flowing through the microfluidic channel, where the digital frames of this movie are processed to count the number of the labeled cells within the target solution of interest. Using a similar opto-fluidic design, we can also image these fluorescently labeled cells in static mode by e.g. sandwiching the fluorescent particles between two glass slides and capturing their fluorescent images using the cell-phone camera, which can achieve a spatial resolution of e.g. - 10 μm over a very large field-of-view of - 81 mm(2). This cell-phone based fluorescent imaging flow cytometry and microscopy platform might be useful especially in resource limited settings, for e.g. counting of CD4+ T cells toward monitoring of HIV+ patients or for detection of water-borne parasites in drinking water.

Evaluation of the effect of reactant gases mass flow rates on power density in a polymer electrolyte membrane fuel cell

NASA Astrophysics Data System (ADS)

Kahveci, E. E.; Taymaz, I.

2018-03-01

In this study it was experimentally investigated the effect of mass flow rates of reactant gases which is one of the most important operational parameters of polymer electrolyte membrane (PEM) fuel cell on power density. The channel type is serpentine and single PEM fuel cell has an active area of 25 cm2. Design-Expert 8.0 (trial version) was used with four variables to investigate the effect of variables on the response using. Cell temperature, hydrogen mass flow rate, oxygen mass flow rate and humidification temperature were selected as independent variables. In addition, the power density was used as response to determine the combined effects of these variables. It was kept constant cell and humidification temperatures while changing mass flow rates of reactant gases. From the results an increase occurred in power density with increasing the hydrogen flow rates. But oxygen flow rate does not have a significant effect on power density within determined mass flow rates.

Redox flow cell energy storage systems

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1979-01-01

NASA-Redox systems are electrochemical storage devices that use two fully soluble Redox couples, anode and cathode fluids, as active electrode materials separated by a highly selective ion exchange membrane. The reactants are contained in large storage tanks and pumped through a stack of Redox flow cells where the electrochemical reactions (reduction and oxidation) take place at porous carbon felt electrodes. A string or stack of these power producing cells is connected in series in a bipolar manner. Redox energy storage systems promise to be inexpensive and possess many features that provide for flexible design, long life, high reliability and minimal operation and maintenance costs. These features include independent sizing of power and storage capacity requirements and inclusion within the cell stack of a cell that monitors the state of charge of the system as a whole, and a rebalance cell which permits continuous correction to be made for minor side reactions that would tend to result in the anode fluid and cathode fluids becoming electrochemically out of balance. These system features are described and discussed.

A hard-soft microfluidic-based biosensor flow cell for SPR imaging application.

PubMed

Liu, Changchun; Cui, Dafu; Li, Hui

2010-09-15

An ideal microfluidic-based biosensor flow cell should have not only a "soft" interface for high strength sealing with biosensing chips, but also "hard" macro-to-micro interface for tubing connection. Since these properties are exclusive of each other, no one material can provide the advantages of both. In this paper, we explore the application of a SiO(2) thin film, deposited by plasma-enhanced chemical vapor deposition (PECVD) technology, as an intermediate layer for irreversibly adhering polydimethylsiloxane (PDMS) to plastic substrate, and develop a hard-soft, compact, robust microfluidic-based biosensor flow cell for the multi-array immunoassay application of surface plasmon resonance (SPR) imaging. This hard-soft biosensor flow cell consists of one rigid, computer numerically controlled (CNC)-machined poly(methyl methacrylate) (PMMA) base coated with a 200 nm thick SiO(2) thin film, and one soft PDMS microfluidic layer. This novel microfluidic-based biosensor flow cell does not only keep the original advantage of conventional PDMS-based biosensor flow cell such as the intrinsically soft interface, easy-to-fabrication, and low cost, but also has a rigid, robust, easy-to-use interface to tubing connection and can be operated up to 185 kPa in aqueous environments without failure. Its application was successfully demonstrated with two types of experiments by coupling with SPR imaging biosensor: the real-time monitoring of the immunoglobulin G (IgG) interaction, as well as the detection of sulfamethoxazole (SMOZ) and sulfamethazine (SMZ) with the sensitivity of 3.5 and 0.6 ng/mL, respectively. This novel hard-soft microfluidic device is also useful for a variety of other biosensor flow cells. Copyright 2010 Elsevier B.V. All rights reserved.

Flow microfluorometric analysis of phagocyte degranulation in bacteria-infected whole human blood cell cultures

NASA Astrophysics Data System (ADS)

Kravtsov, Alexander L.; Bobyleva, Elena V.; Grebenyukova, Tatyana P.; Kuznetsov, Oleg S.; Kulyash, Youri V.

2002-07-01

A quantitative flow microfluorometric method was used to study the intensity of human blood phagocyte degranulation in response to viable staphylococcus aureus or Yersinia pestis cells. Microorganisms were added directly to defibrinated whole blood. Uninfected and infected blood samples were incubated at 37 degrees C to 8 h. The results were recorded in dynamics after the staining of whole blood with acridine orange solution. Lymphocytes with a low azurophilic granule per cell content were discriminated from phagocytes by the measurement of single cell red cytoplasmic granule fluorescence. 30,000 cells in each sample were examined. S. aureus cells caused a dose-dependent decrease in the number of phagocytes having a high red cytoplasmic fluorescence intensity and a corresponding increase in the weakly fluorescence cell population. In the presence of an initial S. aureus-to-phagocyte ratio more than 1:1, degranulation was measured after 3 h of incubation and to 8 h the percentage of degranulated phagocytes was at least 100 percent Y. pestis cells grown for 48 h at 28 degrees C caused at same condition as the degranulation only about 50 percent of cells. Y.pestis EV cells preincubated in broth for 12 h at 37 degrees C did no stimulate the phahocyte degranulation. The results of these studies suggest that analysis of cell populations via flow microfluorimeter technology may be a powerful tool in analysis bacterial infection.

High-speed cell recognition algorithm for ultrafast flow cytometer imaging system

NASA Astrophysics Data System (ADS)

Zhao, Wanyue; Wang, Chao; Chen, Hongwei; Chen, Minghua; Yang, Sigang

2018-04-01

An optical time-stretch flow imaging system enables high-throughput examination of cells/particles with unprecedented high speed and resolution. A significant amount of raw image data is produced. A high-speed cell recognition algorithm is, therefore, highly demanded to analyze large amounts of data efficiently. A high-speed cell recognition algorithm consisting of two-stage cascaded detection and Gaussian mixture model (GMM) classification is proposed. The first stage of detection extracts cell regions. The second stage integrates distance transform and the watershed algorithm to separate clustered cells. Finally, the cells detected are classified by GMM. We compared the performance of our algorithm with support vector machine. Results show that our algorithm increases the running speed by over 150% without sacrificing the recognition accuracy. This algorithm provides a promising solution for high-throughput and automated cell imaging and classification in the ultrafast flow cytometer imaging platform.

Continuous flow microfluidic separation and processing of rare cells and bioparticles found in blood - A review.

PubMed

Antfolk, Maria; Laurell, Thomas

2017-05-01

Rare cells in blood, such as circulating tumor cells or fetal cells in the maternal circulation, posses a great prognostic or diagnostic value, or for the development of personalized medicine, where the study of rare cells could provide information to more specifically targeted treatments. When conventional cell separation methods, such as flow cytometry or magnetic activated cell sorting, have fallen short other methods are desperately sought for. Microfluidics have been extensively used towards isolating and processing rare cells as it offers possibilities not present in the conventional systems. Furthermore, microfluidic methods offer new possibilities for cell separation as they often rely on non-traditional biomarkers and intrinsic cell properties. This offers the possibility to isolate cell populations that would otherwise not be targeted using conventional methods. Here, we provide an extensive review of the latest advances in continuous flow microfluidic rare cell separation and processing with each cell's specific characteristics and separation challenges as a point of view. Copyright © 2017 Elsevier B.V. All rights reserved.

The absolute counting of red cell-derived microparticles with red cell bead by flow rate based assay.

PubMed

Nantakomol, Duangdao; Imwong, Malika; Soontarawirat, Ingfar; Kotjanya, Duangporn; Khakhai, Chulalak; Ohashi, Jun; Nuchnoi, Pornlada

2009-05-01

Activation of red blood cell is associated with the formation of red cell-derived microparticles (RMPs). Analysis of circulating RMPs is becoming more refined and clinically useful. A quantitative Trucount tube method is the conventional method uses for quantitating RMPs. In this study, we validated a quantitative method called "flow rate based assay using red cell bead (FCB)" to measure circulating RMPs in the peripheral blood of healthy subjects. Citrated blood samples collected from 30 cases of healthy subjects were determined the RMPs count by using double labeling of annexin V-FITC and anti-glycophorin A-PE. The absolute RMPs numbers were measured by FCB, and the results were compared with the Trucount or with flow rate based calibration (FR). Statistical correlation and agreement were analyzed using linear regression and Bland-Altman analysis. There was no significant difference in the absolute number of RMPs quantitated by FCB when compared with those two reference methods including the Trucount tube and FR method. The absolute RMPs count obtained from FCB method was highly correlated with those obtained from Trucount tube (r(2) = 0.98, mean bias 4 cell/microl, limit of agreement [LOA] -20.3 to 28.3 cell/microl), and FR method (r(2) = 1, mean bias 10.3 cell/microl, and LOA -5.5 to 26.2 cell/microl). This study demonstrates that FCB is suitable and more affordable for RMPs quantitation in the clinical samples. This method is a low cost and interchangeable to latex bead-based method for generating the absolute counts in the resource-limited areas. (c) 2008 Clinical Cytometry Society.

Gradient isolator for flow field of fuel cell assembly

DOEpatents

Ernst, W.D.

1999-06-15

Isolator(s) include isolating material and optionally gasketing material strategically positioned within a fuel cell assembly. The isolating material is disposed between a solid electrolyte and a metal flow field plate. Reactant fluid carried by flow field plate channel(s) forms a generally transverse electrochemical gradient. The isolator(s) serve to isolate electrochemically a portion of the flow field plate, for example, transversely outward from the channel(s), from the electrochemical gradient. Further, the isolator(s) serve to protect a portion of the solid electrolyte from metallic ions. 4 figs.

Gradient isolator for flow field of fuel cell assembly

DOEpatents

Ernst, William D.

1999-01-01

Isolator(s) include isolating material and optionally gasketing material strategically positioned within a fuel cell assembly. The isolating material is disposed between a solid electrolyte and a metal flow field plate. Reactant fluid carried by flow field plate channel(s) forms a generally transverse electrochemical gradient. The isolator(s) serve to isolate electrochemically a portion of the flow field plate, for example, transversely outward from the channel(s), from the electrochemical gradient. Further, the isolator(s) serve to protect a portion of the solid electrolyte from metallic ions.

Arterial specification of endothelial cells derived from human induced pluripotent stem cells in a biomimetic flow bioreactor.

PubMed

Sivarapatna, Amogh; Ghaedi, Mahboobe; Le, Andrew V; Mendez, Julio J; Qyang, Yibing; Niklason, Laura E

2015-01-01

Endothelial cells (ECs) exist in different microenvironments in vivo, including under different levels of shear stress in arteries versus veins. Standard stem cell differentiation protocols to derive ECs and EC-subtypes from human induced pluripotent stem cells (hiPSCs) generally use growth factors or other soluble factors in an effort to specify cell fate. In this study, a biomimetic flow bioreactor was used to subject hiPSC-derived ECs (hiPSC-ECs) to shear stress to determine the impacts on phenotype and upregulation of markers associated with an anti-thrombotic, anti-inflammatory, arterial-like phenotype. The in vitro bioreactor system was able to efficiently mature hiPSC-ECs into arterial-like cells in 24 h, as demonstrated by qRT-PCR for arterial markers EphrinB2, CXCR4, Conexin40 and Notch1, as well protein-level expression of Notch1 intracellular domain (NICD). Furthermore, the exogenous addition of soluble factors was not able to fully recapitulate this phenotype that was imparted by shear stress exposure. The induction of these phenotypic changes was biomechanically mediated in the shear stress bioreactor. This biomimetic flow bioreactor is an effective means for the differentiation of hiPSC-ECs toward an arterial-like phenotype, and is amenable to scale-up for culturing large quantities of cells for tissue engineering applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Telomere content measurement in human hematopoietic cells: Comparative analysis of qPCR and Flow-FISH techniques.

PubMed

Wand, Taylor; Fang, Mike; Chen, Christina; Hardy, Nathan; McCoy, J Philip; Dumitriu, Bogdan; Young, Neal S; Biancotto, Angélique

2016-10-01

Abnormal telomere lengths have been linked to cancer and other hematologic disorders. Determination of mean telomere content (MTC) is traditionally performed by Southern blotting and densitometry, giving a mean telomere restriction fragment (TRF) value for the total cell population studied. Here, we compared a quantitative Polymerase Chain Reaction approach (qPCR) and a flow cytometric approach, fluorescence in situ hybridization (Flow-FISH), to evaluate telomere content distribution in total patient peripheral blood mononuclear cells or specific cell populations. Flow-FISH is based on in situ hybridization using a fluorescein-labeled peptide nucleic acid (PNA) (CCCTAA) 3 probe and DNA staining with propidium iodide. We showed that both qPCR and Flow-FISH provide a robust measurement, with Flow-FISH measuring a relative content longer than qPCR at a single cell approach and that TRF2 fluorescence intensity did not correlate with MTC. Both methods showed comparable telomere content reduction with age, and the rate of relative telomere loss was similar. Published 2016 Wiley Periodicals Inc. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals Inc. This article is a US government work and, as such, is in the public domain in the United States of America.

Transport studies in polymer electrolyte fuel cell with porous metallic flow field at ultra high current density

NASA Astrophysics Data System (ADS)

Srouji, Abdul-Kader

Achieving cost reduction for polymer electrolyte fuel cells (PEFC) requires a simultaneous effort in increasing power density while reducing precious metal loading. In PEFCs, the cathode performance is often limiting due to both the slow oxygen reduction reaction (ORR), and mass transport limitation caused by limited oxygen diffusion and liquid water flooding at high current density. This study is motivated by the achievement of ultra-high current density through the elimination of the channel/land (C/L) paradigm in PEFC flow field design. An open metallic element (OME) flow field capable of operating at unprecedented ultra-high current density (3 A/cm2) introduces new advantages and limitations for PEFC operation. The first part of this study compares the OME with a conventional C/L flow field, through performance and electrochemical diagnostic tools such as electrochemical impedance spectroscopy (EIS). The results indicate the uniqueness of the OME's mass transport improvement. No sign of operation limitation due to flooding is noted. The second part specifically examines water management at high current density using the OME flow field. A unique experimental setup is developed to measure steady-state and transient net water drag across the membrane, in order to characterize the fundamental aspects of water transport at high current density with the OME. Instead of flooding, the new limitation is identified to be anode side dry-out of the membrane, caused by electroosmotic drag. The OME improves water removal from the cathode, which immediately improves oxygen transport and performance. However, the low water content in the cathode reduces back diffusion of water to the membrane, and electroosmotic drag dominates at high current density, leading to dry-out. The third part employs the OME flow field as a tool that avoids C/L effects endemic to a typical flow field, in order to study oxygen transport resistance at the catalyst layer of a PEFC. In open literature, a

Flow characterization of a spinner flask for induced pluripotent stem cell culture application.

PubMed

Ismadi, Mohd-Zulhilmi; Gupta, Priyanka; Fouras, Andreas; Verma, Paul; Jadhav, Sameer; Bellare, Jayesh; Hourigan, Kerry

2014-01-01

We present detailed quantitative measurement analyses for flow in a spinner flask with spinning rates between 20 to 45 RPM, utilizing the optical velocimetry measurement technique of Particle Image Velocimetry (PIV). A partial section of the impeller was immersed in the working fluid to reduce the shear forces induced on the cells cultured on microcarriers. Higher rotational speeds improved the mixing effect in the medium at the expense of a higher shear environment. It was found that the mouse induced pluripotent stem (iPS) cells achieved the optimum number of cells over 7 days in 25 RPM suspension culture. This condition translates to 0.0984 Pa of maximum shear stress caused by the interaction of the fluid flow with the bottom surface. However, inverse cell growth was obtained at 28 RPM culture condition. Such a narrow margin demonstrated that mouse iPS cells cultured on microcarriers are very sensitive to mechanical forces. This study provides insight to biomechanical parameters, specifically the shear stress distribution, for a commercially available spinner flask over a wide range of Reynolds number.

Apical constriction drives tissue-scale hydrodynamic flow to mediate cell elongation

PubMed Central

He, Bing; Doubrovinski, Konstantin; Polyakov, Oleg; Wieschaus, Eric

2014-01-01

Epithelial folding mediated by apical constriction converts flat epithelial sheets into multilayered, complex tissue structures and is employed throughout the development in most animals1. Little is known, however, how forces produced near the apical surface of the tissue are transmitted within individual cells to generate the global changes in cell shape that characterize tissue deformation. Here we apply particle tracking velocimetry in gastrulating Drosophila embryos to measure the movement of cytoplasm and plasma membrane during ventral furrow (VF) formation2, 3. We find that cytoplasmic redistribution during the lengthening phase of VF formation can be precisely described by viscous flows that quantitatively match the predictions of hydrodynamics. Cell membranes move with the ambient cytoplasm, with little resistance to or driving force on the flow. Strikingly, apical constriction produces similar flow patterns in mutant embryos that fail to form cells prior to gastrulation (“acellular” embryos), such that the global redistribution of cytoplasm mirrors the summed redistribution occurring in individual cells of wild type embryos. Our results suggest that during the lengthening phase of VF formation, hydrodynamic behavior of the cytoplasm provides the predominant mechanism transmitting apically generated forces deep into the tissue and that cell individualization is dispensable. PMID:24590071

Flow rate calibration to determine cell-derived microparticles and homogeneity of blood components.

PubMed

Noulsri, Egarit; Lerdwana, Surada; Kittisares, Kulvara; Palasuwan, Attakorn; Palasuwan, Duangdao

2017-08-01

Cell-derived microparticles (MPs) are currently of great interest to screening transfusion donors and blood components. However, the current approach to counting MPs is not affordable for routine laboratory use due to its high cost. The current study aimed to investigate the potential use of flow-rate calibration for counting MPs in whole blood, packed red blood cells (PRBCs), and platelet concentrates (PCs). The accuracy of flow-rate calibration was investigated by comparing the platelet counts of an automated counter and a flow-rate calibrator. The concentration of MPs and their origins in whole blood (n=100), PRBCs (n=100), and PCs (n=92) were determined using a FACSCalibur. The MPs' fold-changes were calculated to assess the homogeneity of the blood components. Comparing the platelet counts conducted by automated counting and flow-rate calibration showed an r 2 of 0.6 (y=0.69x+97,620). The CVs of the within-run and between-run variations of flow-rate calibration were 8.2% and 12.1%, respectively. The Bland-Altman plot showed a mean bias of -31,142platelets/μl. MP enumeration revealed both the difference in MP levels and their origins in whole blood, PRBCs, and PCs. Screening the blood components demonstrated high heterogeneity of the MP levels in PCs when compared to whole blood and PRBCs. The results of the present study suggest the accuracy and precision of flow-rate calibration for enumerating MPs. This flow-rate approach is affordable for assessing the homogeneity of MPs in blood components in routine laboratory practice. Copyright © 2017 Elsevier Ltd. All rights reserved.

Extended flow cytometry characterization of normal bone marrow progenitor cells by simultaneous detection of aldehyde dehydrogenase and early hematopoietic antigens: implication for erythroid differentiation studies

PubMed Central

Mirabelli, Peppino; Di Noto, Rosa; Lo Pardo, Catia; Morabito, Paolo; Abate, Giovanna; Gorrese, Marisa; Raia, Maddalena; Pascariello, Caterina; Scalia, Giulia; Gemei, Marica; Mariotti, Elisabetta; Del Vecchio, Luigi

2008-01-01

Background Aldehyde dehydrogenase (ALDH) is a cytosolic enzyme highly expressed in hematopoietic precursors from cord blood and granulocyte-colony stimulating factor mobilized peripheral blood, as well as in bone marrow from patients with acute myeloblastic leukemia. As regards human normal bone marrow, detailed characterization of ALDH+ cells has been addressed by one single study (Gentry et al, 2007). The goal of our work was to provide new information about the dissection of normal bone marrow progenitor cells based upon the simultaneous detection by flow cytometry of ALDH and early hematopoietic antigens, with particular attention to the expression of ALDH on erythroid precursors. To this aim, we used three kinds of approach: i) multidimensional analytical flow cytometry, detecting ALDH and early hematopoietic antigens in normal bone marrow; ii) fluorescence activated cell sorting of distinct subpopulations of progenitor cells, followed by in vitro induction of erythroid differentiation; iii) detection of ALDH+ cellular subsets in bone marrow from pure red cell aplasia patients. Results In normal bone marrow, we identified three populations of cells, namely ALDH+CD34+, ALDH-CD34+ and ALDH+CD34- (median percentages were 0.52, 0.53 and 0.57, respectively). As compared to ALDH-CD34+ cells, ALDH+CD34+ cells expressed the phenotypic profile of primitive hematopoietic progenitor cells, with brighter expression of CD117 and CD133, accompanied by lower display of CD38 and CD45RA. Of interest, ALDH+CD34- population disclosed a straightforward erythroid commitment, on the basis of three orders of evidences. First of all, ALDH+CD34- cells showed a CD71bright, CD105+, CD45- phenotype. Secondly, induction of differentiation experiments evidenced a clear-cut expression of glycophorin A (CD235a). Finally, ALDH+CD34- precursors were not detectable in patients with pure red cell aplasia (PRCA). Conclusion Our study, comparing surface antigen expression of ALDH+/CD34+, ALDH

Isolation of circulating tumor cells using photoacoustic flowmetry and two phase flow

NASA Astrophysics Data System (ADS)

O'Brien, Christine M.; Rood, Kyle D.; Gupta, Sagar K.; Mosley, Jeffrey D.; Goldschmidt, Benjamin S.; Sharma, Nikhilesh; Sengupta, Shramik; Viator, John A.

2011-03-01

Melanoma is the deadliest form of skin cancer, yet current diagnostic methods are inadequately sensitive. Patients must wait until secondary tumors form before malignancy can be diagnosed and treatment prescribed. Detection of cells that have broken off the original tumor and flow through the blood or lymph system can provide data for diagnosing and monitoring cancer. Our group utilizes the photoacoustic effect to detect metastatic melanoma cells, which contain the pigmented granule melanin. As a rapid laser pulse irradiates melanoma, the melanin undergoes thermo-elastic expansion and ultimately creates a photoacoustic wave. Thus, melanoma patient's blood samples can be enriched, leaving the melanoma in a white blood cell (WBC) suspension. Irradiated melanoma cells produce photoacoustic waves, which are detected with a piezoelectric transducer, while the optically transparent WBCs create no signals. Here we report an isolation scheme utilizing two-phase flow to separate detected melanoma from the suspension. By introducing two immiscible fluids through a t-junction into one flow path, the analytes are compartmentalized. Therefore, the slug in which the melanoma cell is located can be identified and extracted from the system. Two-phase immiscible flow is a label free technique, and could be used for other types of pathological analytes.

Transport governs flow-enhanced cell tethering through L-selectin at threshold shear.

PubMed

Yago, Tadayuki; Zarnitsyna, Veronika I; Klopocki, Arkadiusz G; McEver, Rodger P; Zhu, Cheng

2007-01-01

Flow-enhanced cell adhesion is a counterintuitive phenomenon that has been observed in several biological systems. Flow augments L-selectin-dependent adhesion by increasing the initial tethering of leukocytes to vascular surfaces and by strengthening their subsequent rolling interactions. Tethering or rolling might be influenced by physical factors that affect the formation or dissociation of selectin-ligand bonds. We recently demonstrated that flow enhanced rolling of L-selectin-bearing microspheres or neutrophils on P-selectin glycoprotein ligand-1 by force decreased bond dissociation. Here, we show that flow augmented tethering of these microspheres or cells to P-selectin glycoprotein ligand-1 by three transport mechanisms that increased bond formation: sliding of the sphere bottom on the surface, Brownian motion, and molecular diffusion. These results elucidate the mechanisms for flow-enhanced tethering through L-selectin.

A numerical analysis of forces exerted by laminar flow on spreading cells in a parallel plate flow chamber assay.

PubMed

Olivier, L A; Truskey, G A

1993-10-01

Exposure of spreading anchorage-dependent cells to laminar flow is a common technique to measure the strength of cell adhesion. Since cells protrude into the flow stream, the force exerted by the fluid on the cells is a function of cell shape. To assess the relationship between cell shape and the hydrodynamic force on adherent cells, we obtained numerical solutions of the velocity and stress fields around bovine aortic endothelial cells during various stages of spreading and calculated the force required to detach the cells. Morphometric parameters were obtained from light and scanning electron microscopy measurements. Cells were assumed to have a constant volume, but the surface area increased during spreading until the membrane was stretched taut. Two-dimensional models of steady flow were generated using the software packages ANSYS (mesh generation) and FIDAP (problem solution). The validity of the numerical results was tested by comparison with published results for a semicircle in contact with the surface. The drag force and torque were greatest for round cells making initial contact with the surface. During spreading, the drag force and torque declined by factors of 2 and 20, respectively. The calculated forces and moments were used in adhesion models to predict the wall shear stress at which the cells detached. Based upon published values for the bond force and receptor number, round cells should detach at shear stresses between 2.5 and 6 dyn/cm(2), whereas substantially higher stresses are needed to detach spreading and fully spread cells. Results from the simulations indicate that (1) the drag force varies little with cell shape whereas the torque is very sensitive to cell shape, and (2) the increase in the strength of adhesion during spreading is due to increased contact area and receptor densities within the contact area. (c) 1993 John Wiley & Sons, Inc.

Dissipative particle dynamics simulations of deformation and aggregation of healthy and diseased red blood cells in a tube flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Ting; Phan-Thien, Nhan, E-mail: Nhan@nus.edu.sg; Khoo, Boo Cheong

In this paper, we report simulation results assessing the deformation and aggregation of mixed healthy and malaria-infected red blood cells (RBCs) in a tube flow. A three dimensional particle model based on Dissipative Particle Dynamics (DPD) is developed to predict the tube flow containing interacting cells. The cells are also modelled by DPD, with a Morse potential to characterize the cell-cell interaction. As validation tests, a single RBC in a tube flow and two RBCs in a static flow are simulated to examine the cell deformation and intercellular interaction, respectively. The study of two cells, one healthy and the othermore » malaria-infected RBCs in a tube flow demonstrates that the malaria-infected RBC (in the leading position along flow direction) has different effects on the healthy RBC (in the trailing position) at the different stage of parasite development or at the different capillary number. With parasitic development, the malaria-infected RBC gradually loses its deformability, and in turn the corresponding trailing healthy RBC also deforms less due to the intercellular interaction. With increasing capillary number, both the healthy and malaria-infected RBCs are likely to undergo an axisymmetric motion. The minimum intercellular distance becomes small enough so that rouleaux is easily formed, i.e., the healthy and malaria-infected RBCs are difficultly disaggregated.« less

A Lattice Boltzmann Fictitious Domain Method for Modeling Red Blood Cell Deformation and Multiple-Cell Hydrodynamic Interactions in Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Xing; Lin, Guang; Zou, Jianfeng

To model red blood cell (RBC) deformation in flow, the recently developed LBM-DLM/FD method ([Shi and Lim, 2007)29], derived from the lattice Boltzmann method and the distributed Lagrange multiplier/fictitious domain methodthe fictitious domain method, is extended to employ the mesoscopic network model for simulations of red blood cell deformation. The flow is simulated by the lattice Boltzmann method with an external force, while the network model is used for modeling red blood cell deformation and the fluid-RBC interaction is enforced by the Lagrange multiplier. To validate parameters of the RBC network model, sThe stretching numerical tests on both coarse andmore » fine meshes are performed and compared with the corresponding experimental data to validate the parameters of the RBC network model. In addition, RBC deformation in pipe flow and in shear flow is simulated, revealing the capacity of the current method for modeling RBC deformation in various flows.« less

High-speed cell recognition algorithm for ultrafast flow cytometer imaging system.

PubMed

Zhao, Wanyue; Wang, Chao; Chen, Hongwei; Chen, Minghua; Yang, Sigang

2018-04-01

An optical time-stretch flow imaging system enables high-throughput examination of cells/particles with unprecedented high speed and resolution. A significant amount of raw image data is produced. A high-speed cell recognition algorithm is, therefore, highly demanded to analyze large amounts of data efficiently. A high-speed cell recognition algorithm consisting of two-stage cascaded detection and Gaussian mixture model (GMM) classification is proposed. The first stage of detection extracts cell regions. The second stage integrates distance transform and the watershed algorithm to separate clustered cells. Finally, the cells detected are classified by GMM. We compared the performance of our algorithm with support vector machine. Results show that our algorithm increases the running speed by over 150% without sacrificing the recognition accuracy. This algorithm provides a promising solution for high-throughput and automated cell imaging and classification in the ultrafast flow cytometer imaging platform. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Response Of Mineralizing And Non-Mineralizing Bone Cells To Fluid Flow: An In Vitro Model For Mechanotransruction

NASA Technical Reports Server (NTRS)

Makuch, Lauren A.

2004-01-01

Humans reach peak bone mass at age 30. After this point, we lose 1 to 2 percent of bone mass each decade. In the microgravity environment of space, astronauts lose bone mass at an accelerated rate of 1 to 2 percent each month. When astronauts travel to Mars, they may be in space for as long as 3 years. During this time, they may lose about half of their bone mass from weight-bearing bones. This loss may be irreversible. The drastic loss in bone that astronauts experience in space makes them much more vulnerable to fractures. In addition, the corresponding removal of calcium from bone results in higher levels of calcium in the blood, which increases the risk of developing kidney stones. Currently, studies are being conducted which investigate factors governing bone adaptation and mechanotransduction. Bone is constantly adapting in response to mechanical stimuli. Increased mechanical loading stimulates bone formation and suppresses bone resorption. Reduction in mechanical loading caused by bedrest, disuse, or microgravity results in decreased bone formation and possibly increased bone resorption. Osteoblasts and osteoclasts are the two main cell types that participate in bone remodeling. Osteoblasts are anabolic (bone-forming) cells and osteoclasts are catabolic (bone-resorbing) cells. In microgravity, the activity of osteoblasts slows down and the activity of osteoclasts may speed up, causing a loss of bone density. Mechanotransduction, the molecular mechanism by which mechanical stimuli are converted to biochemical signals, is not yet understood. Exposure of cells to fluid flow imposes a shear stress on the cells. Several studies have shown that the shear stress that results from fluid flow induces a cellular response similar to that induced by mechanical loading. Thus, fluid flow can be used as an in vitro model to simulate the mechanical stress that bone cells experience in vivo. Previous in vitro studies have shown that fluid flow induces several responses in

Overexpression of syndecan-1, MUC-1, and putative stem cell markers in breast cancer leptomeningeal metastasis: a cerebrospinal fluid flow cytometry study.

PubMed

Cordone, Iole; Masi, Serena; Summa, Valentina; Carosi, Mariantonia; Vidiri, Antonello; Fabi, Alessandra; Pasquale, Alessia; Conti, Laura; Rosito, Immacolata; Carapella, Carmine Maria; Villani, Veronica; Pace, Andrea

2017-04-11

Cancer is a mosaic of tumor cell subpopulations, where only a minority is responsible for disease recurrence and cancer invasiveness. We focused on one of the most aggressive circulating tumor cells (CTCs) which, from the primitive tumor, spreads to the central nervous system (CNS), evaluating the expression of prognostic and putative cancer stem cell markers in breast cancer (BC) leptomeningeal metastasis (LM). Flow cytometry immunophenotypic analysis of cerebrospinal fluid (CSF) samples (4.5 ml) was performed in 13 consecutive cases of BCLM. Syndecan-1 (CD138), MUC-1 (CD227) CD45, CD34, and the putative cancer stem cell markers CD15, CD24, CD44, and CD133 surface expression were evaluated on CSF floating tumor cells. The tumor-associated leukocyte population was also characterized. Despite a low absolute cell number (8 cell/μl, range 1-86), the flow cytometry characterization was successfully conducted in all the samples. Syndecan-1 and MUC-1 overexpression was documented on BC cells in all the samples analyzed; CD44, CD24, CD15, and CD133 in 77%, 75%, 70%, and 45% of cases, respectively. A strong syndecan-1 and MUC-1 expression was also documented by immunohistochemistry on primary breast cancer tissues, performed in four patients. The CSF tumor population was flanked by T lymphocytes, with a different immunophenotype between the CSF and peripheral blood samples (P ≤ 0.02). Flow cytometry can be successfully employed for solid tumor LM characterization even in CSF samples with low cell count. This in vivo study documents that CSF floating BC cells overexpress prognostic and putative cancer stem cell biomarkers related to tumor invasiveness, potentially representing a molecular target for circulating tumor cell detection and LM treatment monitoring, as well as a primary target for innovative treatment strategies. The T lymphocyte infiltration, documented in all CSF samples, suggests a possible involvement of the CNS lymphatic system in both lymphoid and

A numerical study of blood flow using mixture theory

PubMed Central

Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F.

2014-01-01

In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner–Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM® was developed and employed to simulate a specific problem, namely blood flow in a two dimensional micro-channel, is studied. Finally to better understand this two-component flow system and the effects of the different parameters, the equations are made dimensionless and a parametric study is performed. PMID:24791016

A numerical study of blood flow using mixture theory.

PubMed

Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F

2014-03-01

In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner-Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM ® was developed and employed to simulate a specific problem, namely blood flow in a two dimensional micro-channel, is studied. Finally to better understand this two-component flow system and the effects of the different parameters, the equations are made dimensionless and a parametric study is performed.

Particle-in-cell simulation study of the scaling of asymmetric magnetic reconnection with in-plane flow shear

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doss, C. E.; Cassak, P. A., E-mail: Paul.Cassak@mail.wvu.edu; Swisdak, M.

2016-08-15

We investigate magnetic reconnection in systems simultaneously containing asymmetric (anti-parallel) magnetic fields, asymmetric plasma densities and temperatures, and arbitrary in-plane bulk flow of plasma in the upstream regions. Such configurations are common in the high-latitudes of Earth's magnetopause and in tokamaks. We investigate the convection speed of the X-line, the scaling of the reconnection rate, and the condition for which the flow suppresses reconnection as a function of upstream flow speeds. We use two-dimensional particle-in-cell simulations to capture the mixing of plasma in the outflow regions better than is possible in fluid modeling. We perform simulations with asymmetric magnetic fields,more » simulations with asymmetric densities, and simulations with magnetopause-like parameters where both are asymmetric. For flow speeds below the predicted cutoff velocity, we find good scaling agreement with the theory presented in Doss et al. [J. Geophys. Res. 120, 7748 (2015)]. Applications to planetary magnetospheres, tokamaks, and the solar wind are discussed.« less

The Geophysical Fluid Flow Cell Experiment

NASA Technical Reports Server (NTRS)

Hart, J. E.; Ohlsen, D.; Kittleman, S.; Borhani, N.; Leslie, F.; Miller, T.

1999-01-01

The Geophysical Fluid Flow Cell (GFFC) experiment performed visualizations of thermal convection in a rotating differentially heated spherical shell of fluid. In these experiments dielectric polarization forces are used to generate a radially directed buoyancy force. This enables the laboratory simulation of a number of geophysically and astrophysically important situations in which sphericity and rotation both impose strong constraints on global scale fluid motions. During USML-2 a large set of experiments with spherically symmetric heating were carried out. These enabled the determination of critical points for the transition to various forms of nonaxisymmetric convection and, for highly turbulent flows, the transition latitudes separating the different modes of motion. This paper presents a first analysis of these experiments as well as data on the general performance of the instrument during the USML-2 flight.

Measurement of Flow Pattern Within a Rotating Stall Cell in an Axial Compressor

NASA Technical Reports Server (NTRS)

Lepicovsky, Jan; Braunscheidel, Edward P.

2006-01-01

Effective active control of rotating stall in axial compressors requires detailed understanding of flow instabilities associated with this compressor regime. Newly designed miniature high frequency response total and static pressure probes as well as commercial thermoanemometric probes are suitable tools for this task. However, during the rotating stall cycle the probes are subjected to flow direction changes that are far larger than the range of probe incidence acceptance, and therefore probe data without a proper correction would misrepresent unsteady variations of flow parameters. A methodology, based on ensemble averaging, is proposed to circumvent this problem. In this approach the ensemble averaged signals acquired for various probe setting angles are segmented, and only the sections for probe setting angles close to the actual flow angle are used for signal recombination. The methodology was verified by excellent agreement between velocity distributions obtained from pressure probe data, and data measured with thermoanemometric probes. Vector plots of unsteady flow behavior during the rotating stall regime indicate reversed flow within the rotating stall cell that spreads over to adjacent rotor blade channels. Results of this study confirmed that the NASA Low Speed Axial Compressor (LSAC) while in a rotating stall regime at rotor design speed exhibits one stall cell that rotates at a speed equal to 50.6 percent of the rotor shaft speed.

Flow cytometric analysis of BDE 47 mediated injury to rainbow trout gill epithelial cells

PubMed Central

Shao, Jing; Dabrowski, Michael J.; White, Collin C.; Kavanagh, Terrance J.; Gallagher, Evan P.

2012-01-01

The polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental contaminants whose residues are increasing in fish, wildlife and human tissues. However, relatively little is known regarding the mechanisms of cell injury caused by PBDE congeners in fish. In the present study, we employed flow cytometry-based analyses to understand the onset and mechanisms of cell injury in rainbow trout gill cells (RTgill-W1 cells) exposed to 2,2′,4,4′-tetrabromodiphenyl ether (BDE 47). Substantial optimization and validation for flow cytometry protocols were required during assay development for the trout gill cell line. Exposure to micromolar concentrations of BDE 47 elicited a significant loss in RTgill-W1 cell viability that was accompanied by a decrease in NAD(P)H autofluorescence, a marker associated with disruption of cellular redox status. This loss in NAD(P)H content was accompanied by a decrease in nonylacridine orange fluorescence, indicating mitochondrial membrane lipid peroxidation. Furthermore, low doses of BDE 47 altered cellular forward angle light scatter (FS, a measure of cell diameter or size) and side light scatter properties (SS, a measure of cellular internal complexity), consistent with the early stages of apoptosis. These changes were more pronounced at higher BDE 47 concentrations, which lead to an increase in the percentage of cells undergoing frank apoptosis as evidenced by sub-G1 DNA content. Apoptosis was also observed at a relatively low dose (3.2 μM) of BDE 47 if cells were exposed for an extended period of time (24 hr). Collectively, the results of these studies indicate that exposure of rainbow trout gill cells to BDE47 is associated with the induction of apoptosis likely originating from disruption of cellular redox status and mitochondrial oxidative injury. The current report extends observations in other species demonstrating that oxidative stress is an important mechanism of BDE 47 mediated cellular toxicity, and supports the use of

Surface deformation and shear flow in ligand mediated cell adhesion.

PubMed

Sircar, Sarthok; Roberts, Anthony J

2016-10-01

We present a unified, multiscale model to study the attachment/detachment dynamics of two deforming, charged, near spherical cells, coated with binding ligands and subject to a slow, homogeneous shear flow in a viscous, ionic fluid medium. The binding ligands on the surface of the cells experience both attractive and repulsive forces in an ionic medium and exhibit finite resistance to rotation via bond tilting. The microscale drag forces and couples describing the fluid flow inside the small separation gap between the cells, are calculated using a combination of methods in lubrication theory and previously published numerical results. For a selected range of material and fluid parameters, a hysteretic transition of the sticking probability curves (i.e., the function [Formula: see text]) between the adhesion phase (when [Formula: see text]) and the fragmentation phase (when [Formula: see text]) is attributed to a nonlinear relation between the total nanoscale binding forces and the separation gap between the cells. We show that adhesion is favoured in highly ionic fluids, increased deformability of the cells, elastic binders and a higher fluid shear rate (until a critical threshold value of shear rate is reached). Within a selected range of critical shear rates, the continuation of the limit points (i.e., the turning points where the slope of [Formula: see text] changes sign) predict a bistable region, indicating an abrupt switching between the adhesion and the fragmentation regimes. Although, bistability in the adhesion-fragmentation phase diagram of two deformable, charged cells immersed in an ionic aqueous environment has been identified by some in vitro experiments, but until now, has not been quantified theoretically.

The effect of hypnosis on pain and peripheral blood flow in sickle-cell disease: a pilot study

PubMed Central

Bhatt, Ravi R; Martin, Sarah R; Evans, Subhadra; Lung, Kirsten; Coates, Thomas D; Zeltzer, Lonnie K; Tsao, Jennie C

2017-01-01

Background Vaso-occlusive pain crises (VOCs) are the “hallmark” of sickle-cell disease (SCD) and can lead to sympathetic nervous system dysfunction. Increased sympathetic nervous system activation during VOCs and/or pain can result in vasoconstriction, which may increase the risk for subsequent VOCs and pain. Hypnosis is a neuromodulatory intervention that may attenuate vascular and pain responsiveness. Due to the lack of laboratory-controlled pain studies in patients with SCD and healthy controls, the specific effects of hypnosis on acute pain-associated vascular responses are unknown. The current study assessed the effects of hypnosis on peripheral blood flow, pain threshold, tolerance, and intensity in adults with and without SCD. Subjects and methods Fourteen patients with SCD and 14 healthy controls were included. Participants underwent three laboratory pain tasks before and during a 30-minute hypnosis session. Peripheral blood flow, pain threshold, tolerance, and intensity before and during hypnosis were examined. Results A single 30-minute hypnosis session decreased pain intensity by a moderate amount in patients with SCD. Pain threshold and tolerance increased following hypnosis in the control group, but not in patients with SCD. Patients with SCD exhibited lower baseline peripheral blood flow and a greater increase in blood flow following hypnosis than controls. Conclusion Given that peripheral vasoconstriction plays a role in the development of VOC, current findings provide support for further laboratory and clinical investigations of the effects of cognitive–behavioral neuromodulatory interventions on pain responses and peripheral vascular flow in patients with SCD. Current results suggest that hypnosis may increase peripheral vasodilation during both the anticipation and experience of pain in patients with SCD. These findings indicate a need for further examination of the effects of hypnosis on pain and vascular responses utilizing a randomized

Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries

NASA Astrophysics Data System (ADS)

Xu, Ao; Shyy, Wei; Zhao, Tianshou

2017-06-01

Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.

Dynamic Microenvironment Induces Phenotypic Plasticity of Esophageal Cancer Cells Under Flow

NASA Astrophysics Data System (ADS)

Calibasi Kocal, Gizem; Güven, Sinan; Foygel, Kira; Goldman, Aaron; Chen, Pu; Sengupta, Shiladitya; Paulmurugan, Ramasamy; Baskin, Yasemin; Demirci, Utkan

2016-12-01

Cancer microenvironment is a remarkably heterogeneous composition of cellular and non-cellular components, regulated by both external and intrinsic physical and chemical stimuli. Physical alterations driven by increased proliferation of neoplastic cells and angiogenesis in the cancer microenvironment result in the exposure of the cancer cells to elevated levels of flow-based shear stress. We developed a dynamic microfluidic cell culture platform utilizing eshopagael cancer cells as model cells to investigate the phenotypic changes of cancer cells upon exposure to fluid shear stress. We report the epithelial to hybrid epithelial/mesenchymal transition as a result of decreasing E-Cadherin and increasing N-Cadherin and vimentin expressions, higher clonogenicity and ALDH positive expression of cancer cells cultured in a dynamic microfluidic chip under laminar flow compared to the static culture condition. We also sought regulation of chemotherapeutics in cancer microenvironment towards phenotypic control of cancer cells. Such in vitro microfluidic system could potentially be used to monitor how the interstitial fluid dynamics affect cancer microenvironment and plasticity on a simple, highly controllable and inexpensive bioengineered platform.

In Vivo Myeloperoxidase Imaging and Flow Cytometry Analysis of Intestinal Myeloid Cells.

PubMed

Hülsdünker, Jan; Zeiser, Robert

2016-01-01

Myeloperoxidase (MPO) imaging is a non-invasive method to detect cells that produce the enzyme MPO that is most abundant in neutrophils, macrophages, and inflammatory monocytes. While lacking specificity for any of these three cell types, MPO imaging can provide guidance for further flow cytometry-based analysis of tissues where these cell types reside. Isolation of leukocytes from the intestinal tract is an error-prone procedure. Here, we describe a protocol for intestinal leukocyte isolation that works reliable in our hands and allows for flow cytometry-based analysis, in particular of neutrophils.

Feasibility study of stain-free classification of cell apoptosis based on diffraction imaging flow cytometry and supervised machine learning techniques.

PubMed

Feng, Jingwen; Feng, Tong; Yang, Chengwen; Wang, Wei; Sa, Yu; Feng, Yuanming

2018-06-01

This study was to explore the feasibility of prediction and classification of cells in different stages of apoptosis with a stain-free method based on diffraction images and supervised machine learning. Apoptosis was induced in human chronic myelogenous leukemia K562 cells by cis-platinum (DDP). A newly developed technique of polarization diffraction imaging flow cytometry (p-DIFC) was performed to acquire diffraction images of the cells in three different statuses (viable, early apoptotic and late apoptotic/necrotic) after cell separation through fluorescence activated cell sorting with Annexin V-PE and SYTOX® Green double staining. The texture features of the diffraction images were extracted with in-house software based on the Gray-level co-occurrence matrix algorithm to generate datasets for cell classification with supervised machine learning method. Therefore, this new method has been verified in hydrogen peroxide induced apoptosis model of HL-60. Results show that accuracy of higher than 90% was achieved respectively in independent test datasets from each cell type based on logistic regression with ridge estimators, which indicated that p-DIFC system has a great potential in predicting and classifying cells in different stages of apoptosis.

Assessment of cell concentration and viability of isolated hepatocytes using flow cytometry.

PubMed

Wigg, Alan J; Phillips, John W; Wheatland, Loretta; Berry, Michael N

2003-06-01

The assessment of cell concentration and viability of freshly isolated hepatocyte preparations has been traditionally performed using manual counting with a Neubauer counting chamber and staining for trypan blue exclusion. Despite the simple and rapid nature of this assessment, concerns about the accuracy of these methods exist. Simple flow cytometry techniques which determine cell concentration and viability are available yet surprisingly have not been extensively used or validated with isolated hepatocyte preparations. We therefore investigated the use of flow cytometry using TRUCOUNT Tubes and propidium iodide staining to measure cell concentration and viability of isolated rat hepatocytes in suspension. Analysis using TRUCOUNT Tubes provided more accurate and reproducible measurement of cell concentration than manual cell counting. Hepatocyte viability, assessed using propidium iodide, correlated more closely than did trypan blue exclusion with all indicators of hepatocyte integrity and function measured (lactate dehydrogenase leakage, cytochrome p450 content, cellular ATP concentration, ammonia and lactate removal, urea and albumin synthesis). We conclude that flow cytometry techniques can be used to measure cell concentration and viability of isolated hepatocyte preparations. The techniques are simple, rapid, and more accurate than manual cell counting and trypan blue staining and the results are not affected by protein-containing media.

Flow-through electroporation based on constant voltage for large-volume transfection of cells.

PubMed

Geng, Tao; Zhan, Yihong; Wang, Hsiang-Yu; Witting, Scott R; Cornetta, Kenneth G; Lu, Chang

2010-05-21

Genetic modification of cells is a critical step involved in many cell therapy and gene therapy protocols. In these applications, cell samples of large volume (10(8)-10(9)cells) are often processed for transfection. This poses new challenges for current transfection methods and practices. Here we present a novel flow-through electroporation method for delivery of genes into cells at high flow rates (up to approximately 20 mL/min) based on disposable microfluidic chips, a syringe pump, and a low-cost direct current (DC) power supply that provides a constant voltage. By eliminating pulse generators used in conventional electroporation, we dramatically lowered the cost of the apparatus and improved the stability and consistency of the electroporation field for long-time operation. We tested the delivery of pEFGP-C1 plasmids encoding enhanced green fluorescent protein into Chinese hamster ovary (CHO-K1) cells in the devices of various dimensions and geometries. Cells were mixed with plasmids and then flowed through a fluidic channel continuously while a constant voltage was established across the device. Together with the applied voltage, the geometry and dimensions of the fluidic channel determined the electrical parameters of the electroporation. With the optimal design, approximately 75% of the viable CHO cells were transfected after the procedure. We also generalize the guidelines for scaling up these flow-through electroporation devices. We envision that this technique will serve as a generic and low-cost tool for a variety of clinical applications requiring large volume of transfected cells. Copyright 2010 Elsevier B.V. All rights reserved.

Cell stimulus and lysis in a microfluidic device with segmented gas-liquid flow.

PubMed

El-Ali, Jamil; Gaudet, Suzanne; Günther, Axel; Sorger, Peter K; Jensen, Klavs F

2005-06-01

We describe a microfluidic device with rapid stimulus and lysis of mammalian cells for resolving fast transient responses in cell signaling networks. The device uses segmented gas-liquid flow to enhance mixing and has integrated thermoelectric heaters and coolers to control the temperature during cell stimulus and lysis. Potential negative effects of segmented flow on cell responses are investigated in three different cell types, with no morphological changes and no activation of the cell stress-sensitive mitogen activated protein kinases observed. Jurkat E6-1 cells are stimulated in the device using alpha-CD3, and the resulting activations of ERK and JNK are presented for different time points. Stimulation of cells performed on chip results in pathway activation identical to that of conventionally treated cells under the same conditions.

Optimization of polymer electrolyte membrane fuel cell flow channels using a genetic algorithm

NASA Astrophysics Data System (ADS)

Catlin, Glenn; Advani, Suresh G.; Prasad, Ajay K.

The design of the flow channels in PEM fuel cells directly impacts the transport of reactant gases to the electrodes and affects cell performance. This paper presents results from a study to optimize the geometry of the flow channels in a PEM fuel cell. The optimization process implements a genetic algorithm to rapidly converge on the channel geometry that provides the highest net power output from the cell. In addition, this work implements a method for the automatic generation of parameterized channel domains that are evaluated for performance using a commercial computational fluid dynamics package from ANSYS. The software package includes GAMBIT as the solid modeling and meshing software, the solver FLUENT, and a PEMFC Add-on Module capable of modeling the relevant physical and electrochemical mechanisms that describe PEM fuel cell operation. The result of the optimization process is a set of optimal channel geometry values for the single-serpentine channel configuration. The performance of the optimal geometry is contrasted with a sub-optimal one by comparing contour plots of current density, oxygen and hydrogen concentration. In addition, the role of convective bypass in bringing fresh reactant to the catalyst layer is examined in detail. The convergence to the optimal geometry is confirmed by a bracketing study which compares the performance of the best individual to those of its neighbors with adjacent parameter values.

Combining Cell Type-Restricted Adenoviral Targeting with Immunostaining and Flow Cytometry to Identify Cells-of-Origin of Lung Cancer.

PubMed

Best, Sarah A; Kersbergen, Ariena; Asselin-Labat, Marie-Liesse; Sutherland, Kate D

2018-01-01

Lung cancers display considerable intertumoral heterogeneity, leading to the classification of distinct tumor subtypes. Our understanding of the genetic aberrations that underlie tumor subtypes has been greatly enhanced by recent genomic sequencing studies and state-of-the-art gene targeting technologies, highlighting evidence that distinct lung cancer subtypes may be derived from different "cells-of-origin". Here, we describe the intra-tracheal delivery of cell type-restricted Ad5-Cre viruses into the lungs of adult mice, combined with immunohistochemical and flow cytometry strategies for the detection of lung cancer-initiating cells in vivo.

Detection and isolation of rare cells by 2-step enrichment high-speed flow cytometry/cell sorting and single cell LEAP laser ablation

NASA Astrophysics Data System (ADS)

Zordan, M. D.; Leary, James F.

2011-02-01

The clonal isolation of rare cells, especially cancer and stem cells, in a population is important to the development of improved medical treatment. We have demonstrated that the Laser-Enabled Analysis and Processing (LEAP, Cyntellect Inc., San Diego, CA) instrument can be used to efficiently produce single cell clones by photoablative dilution. Additionally, we have also shown that cells present at low frequencies can be cloned by photoablative dilution after they are pre-enriched by flow cytometry based cell sorting. Circulating tumor cells were modeled by spiking isolated peripheral blood cells with cells from the lung carcinoma cell line A549. Flow cytometry based cell sorting was used to perform an enrichment sort of A549 cells directly into a 384 well plate. Photoablative dilution was performed with the LEAPTM instrument to remove any contaminating cells, and clonally isolate 1 side population cell per well. We were able to isolate and grow single clones of side population cells using this method at greater than 90% efficiency. We have developed a 2 step method that is able to perform the clonal isolation of rare cells based on a medically relevant functional phenotype.

Interaction between endothelial cells and albumin encapsulated droplets in Poiseuille flow

NASA Astrophysics Data System (ADS)

Seda, Robinson; Fowlkes, J. Brian; Bull, Joseph

2012-11-01

Acoustic droplet vaporization (ADV) of DDFP encapsulated microdroplets has the ability to transform these emulsions into larger gas emboli capable of occluding blood vessels for therapy. An albumin shell is able to stabilize the droplet's superheated core, but can also interact with endothelial cells (EC) at the vessel wall if in close proximity. Radial migration of these microdroplets could bring them close enough to make this interaction possible leading to bioeffects that include cell detachment and death if an ADV event occurs. The purpose of this study is to investigate the hydrodynamic conditions (i.e. shear stresses) that make possible this EC-droplet interaction. A flow chamber coated with a monolayer of EC and connected to a syringe pump is used to flow a DDFP droplet solution at physiological shear stresses (1-50 dyne/cm2) and inspected for droplet attachment. Droplets have been observed to interact and reversibly attach to EC in a static environment, thus it is expected that at low shear stress values interaction and further attachment will be possible. Knowing the flow conditions at which this interaction is likely to occur will aid in preventative measures to avoid significant bioeffects associated with ADV near the vessel wall. This work is supported by NIH grant R01EB006476.

A Comparison of Flow-Through Versus Non-Flow-Through Proton Exchange Membrane Fuel Cell Systems for NASA's Exploration Missions

NASA Technical Reports Server (NTRS)

Hoberecht, Mark A.

2010-01-01

As part of the Exploration Technology Development Program (ETDP) under the auspices of the Exploration Systems Mission Directorate (ESMD), NASA is developing both primary fuel cell power systems and regenerative fuel cell (RFC) energy storage systems within the fuel cell portion of the Energy Storage Project. This effort is being led by the NASA Glenn Research Center (GRC) in partnership with the NASA Johnson Space Center (JSC), Jet Propulsion Laboratory (JPL), NASA Kennedy Space Center (KSC), and industrial partners. The development goals are to improve fuel cell and electrolysis stack electrical performance, reduce system mass, volume, and parasitic power requirements, and increase system life and reliability. A major focus of this effort has been the parallel development of both flow-through and non-flow-through proton exchange membrane (PEM) primary fuel cell power systems. The plan has been, at the appropriate time, to select a single primary fuel cell technology for eventual flight hardware development. Ideally, that appropriate time would occur after both technologies have achieved a technology readiness level (TRL) of six, which represents an engineering model fidelity PEM fuel cell system being successfully tested in a relevant environment. Budget constraints in fiscal year 2009 and beyond have prevented NASA from continuing to pursue the parallel development of both primary fuel cell options. Because very limited data exists for either system, a toplevel, qualitative assessment based on engineering judgement was performed expeditiously to provide guidance for a selection. At that time, the non-flow-through technology was selected for continued development because of potentially major advantages in terms of weight, volume, parasitic power, reliability, and life. This author believes that the advantages are significant enough, and the potential benefits great enough, to offset the higher state of technology readiness of flow-through technology. This paper

Comparison of cell centered and cell vertex scheme in the calculation of high speed compressible flows

NASA Astrophysics Data System (ADS)

Rahman, Syazila; Yusoff, Mohd. Zamri; Hasini, Hasril

2012-06-01

This paper describes the comparison between the cell centered scheme and cell vertex scheme in the calculation of high speed compressible flow properties. The calculation is carried out using Computational Fluid Dynamic (CFD) in which the mass, momentum and energy equations are solved simultaneously over the flow domain. The geometry under investigation consists of a Binnie and Green convergent-divergent nozzle and structured mesh scheme is implemented throughout the flow domain. The finite volume CFD solver employs second-order accurate central differencing scheme for spatial discretization. In addition, the second-order accurate cell-vertex finite volume spatial discretization is also introduced in this case for comparison. The multi-stage Runge-Kutta time integration is implemented for solving a set of non-linear governing equations with variables stored at the vertices. Artificial dissipations used second and fourth order terms with pressure switch to detect changes in pressure gradient. This is important to control the solution stability and capture shock discontinuity. The result is compared with experimental measurement and good agreement is obtained for both cases.

FISH-Flow, a protocol for the concurrent detection of mRNA and protein in single cells using fluorescence in situ hybridization and flow cytometry

PubMed Central

Arrigucci, Riccardo; Bushkin, Yuri; Radford, Felix; Lakehal, Karim; Vir, Pooja; Pine, Richard; Martin, December; Sugarman, Jeffrey; Zhao, Yanlin; Yap, George S; Lardizabal, Alfred A; Tyagi, Sanjay; Gennaro, Maria Laura

2017-01-01

We describe a flow-cytometry-based protocol for intracellular mRNA measurements in nonadherent mammalian cells using fluorescence in situ hybridization (FISH) probes. The method, which we call FISH-Flow, allows for high-throughput multiparametric measurements of gene expression, a task that was not feasible with earlier, microscopy-based approaches. The FISH-Flow protocol involves cell fixation, permeabilization and hybridization with a set of fluorescently labeled oligonucleotide probes. In this protocol, surface and intracellular protein markers can also be stained with fluorescently labeled antibodies for simultaneous protein and mRNA measurement. Moreover, a semiautomated, single-tube version of the protocol can be performed with a commercially available cell-wash device that reduces cell loss, operator time and interoperator variability. It takes ~30 h to perform this protocol. An example of FISH-Flow measurements of cytokine mRNA induction by ex vivo stimulation of primed T cells with specific antigens is described. PMID:28518171

Electrochemical study of multi-electrode microbial fuel cells under fed-batch and continuous flow conditions

NASA Astrophysics Data System (ADS)

Ren, Lijiao; Ahn, Yongtae; Hou, Huijie; Zhang, Fang; Logan, Bruce E.

2014-07-01

Power production of four hydraulically connected microbial fuel cells (MFCs) was compared with the reactors operated using individual electrical circuits (individual), and when four anodes were wired together and connected to four cathodes all wired together (combined), in fed-batch or continuous flow conditions. Power production under these different conditions could not be made based on a single resistance, but instead required polarization tests to assess individual performance relative to the combined MFCs. Based on the power curves, power produced by the combined MFCs (2.12 ± 0.03 mW, 200 Ω) was the same as the summed power (2.13 mW, 50 Ω) produced by the four individual reactors in fed-batch mode. With continuous flow through the four MFCs, the maximum power (0.59 ± 0.01 mW) produced by the combined MFCs was slightly lower than the summed maximum power of the four individual reactors (0.68 ± 0.02 mW). There was a small parasitic current flow from adjacent anodes and cathodes, but overall performance was relatively unaffected. These findings demonstrate that optimal power production by reactors hydraulically and electrically connected can be predicted from performance by individual reactors.

Breast epithelium procurement from stereotactic core biopsy washings: flow cytometry-sorted cell count analysis.

PubMed

Stoler, Daniel L; Stewart, Carleton C; Stomper, Paul C

2002-02-01

Molecular studies of breast lesions have been constrained by difficulties in procuring adequate tissues for analyses. Standard procedures are restricted to larger, palpable masses or the use of paraffin-embedded materials, precluding facile procurement of fresh specimens of early lesions. We describe a study to determine the yield and characteristics of sorted cell populations retrieved in core needle biopsy specimen rinses from a spectrum of breast lesions. Cells from 114 consecutive stereotactic core biopsies of mammographic lesions released into saline washes were submitted for flow cytometric analysis. For each specimen, epithelial cells were separated from stromal and blood tissue based on the presence of cytokeratin 8 and 18 markers. Epithelial cell yields based on pathological diagnoses of the biopsy specimen, patient age, and mammographic appearance of the lesion were determined. Biopsies containing malignant lesions yielded significantly higher numbers of cells than were obtained from benign lesion biopsies. Significantly greater cell counts were observed from lesions from women age 50 or above compared with those of younger women. Mammographic density surrounding the biopsy site, the mammographic appearance of the lesion, and the number of cores taken at the time of biopsy appeared to have little effect on the yield of epithelial cells. We demonstrate the use of flow cytometric sorting of stereotactic core needle biopsy washes from lesions spanning the spectrum of breast pathology to obtain epithelial cells in sufficient numbers to meet the requirements of a variety of molecular and genetic analyses.

Single cell kinase signaling assay using pinched flow coupled droplet microfluidics.

PubMed

Ramji, Ramesh; Wang, Ming; Bhagat, Ali Asgar S; Tan Shao Weng, Daniel; Thakor, Nitish V; Teck Lim, Chwee; Chen, Chia-Hung

2014-05-01

Droplet-based microfluidics has shown potential in high throughput single cell assays by encapsulating individual cells in water-in-oil emulsions. Ordering cells in a micro-channel is necessary to encapsulate individual cells into droplets further enhancing the assay efficiency. This is typically limited due to the difficulty of preparing high-density cell solutions and maintaining them without cell aggregation in long channels (>5 cm). In this study, we developed a short pinched flow channel (5 mm) to separate cell aggregates and to form a uniform cell distribution in a droplet-generating platform that encapsulated single cells with >55% encapsulation efficiency beating Poisson encapsulation statistics. Using this platform and commercially available Sox substrates (8-hydroxy-5-(N,N-dimethylsulfonamido)-2-methylquinoline), we have demonstrated a high throughput dynamic single cell signaling assay to measure the activity of receptor tyrosine kinases (RTKs) in lung cancer cells triggered by cell surface ligand binding. The phosphorylation of the substrates resulted in fluorescent emission, showing a sigmoidal increase over a 12 h period. The result exhibited a heterogeneous signaling rate in individual cells and showed various levels of drug resistance when treated with the tyrosine kinase inhibitor, gefitinib.

Dynamic modeling for flow-activated chloride-selective membrane current in vascular endothelial cells.

PubMed

Qin, Kai-Rong; Xiang, Cheng; Cao, Ling-Ling

2011-10-01

In this paper, a dynamic model is proposed to quantify the relationship between fluid flow and Cl(-)-selective membrane current in vascular endothelial cells (VECs). It is assumed that the external shear stress would first induce channel deformation in VECs. This deformation could activate the Cl(-) channels on the membrane, thus allowing Cl(-) transport across the membrane. A modified Hodgkin-Huxley model is embedded into our dynamic system to describe the electrophysiological properties of the membrane, such as the Cl(-)-selective membrane current (I), voltage (V) and conductance. Three flow patterns, i. e., steady flow, oscillatory flow, and pulsatile flow, are applied in our simulation studies. When the extracellular Cl(-) concentration is constant, the I-V characteristics predicted by our dynamic model shows strong consistency with the experimental observations. It is also interesting to note that the Cl(-) currents under different flow patterns show some differences, indicating that VECs distinguish among and respond differently to different types of flows. When the extracellular Cl(-) concentration keeps constant or varies slowly with time (i.e. oscillates at 0.02 Hz), the convection and diffusion of Cl(-) in extracellular space can be ignored and the Cl(-) current is well captured by the modified Hodgkin-Huxley model alone. However, when the extracellular Cl(-) varies fast (i.e., oscillates at 0.2 Hz), the convection and diffusion effect should be considered because the Cl(-) current dynamics is different from the case where the convection-diffusion effect is simply ignored. The proposed dynamic model along with the simulation results could not only provide more insights into the flow-regulated electrophysiological behavior of the cell membrane but also help to reveal new findings in the electrophysiological experimental investigations of VECs in response to dynamic flow and biochemical stimuli.

Investigation and visualization of liquid-liquid flow in a vertically mounted Hele-Shaw cell: flow regimes, velocity and shape of droplets

NASA Astrophysics Data System (ADS)

Shad, S.; Gates, I. D.; Maini, B. B.

2009-11-01

The motion and shape of a liquid drop flowing within a continuous, conveying liquid phase in a vertical Hele-Shaw cell were investigated experimentally. The continuous phase was more viscous and wetted the bounding walls of the Hele-Shaw cell. The gap between the Hele-Shaw plates was set equal to 0.0226 cm. Four different flow regimes were observed: (a) small-droplet flow, (b) elongated-droplet flow, (c) churn flow and (d) channel flow. At low capillary number, that is, when capillary forces are larger than viscous forces, the droplet shape was irregular and changed with time and distance, and it moved with lower velocity than that of the conveying phase. At higher capillary number, several different shapes of stabilized elongated and flattened drops were observed. In contrast to gas-liquid systems, the velocities of droplets are higher than that of conveying liquid. New correlations derived from dimensionless analysis and fitted to the experimental data were generated to predict the elongated-drop velocity and aspect ratio.

Microgravity and bone cell mechanosensitivity: FLOW experiment during the DELTA mission

NASA Astrophysics Data System (ADS)

Bacabac, Rommel G.; Van Loon, Jack J. W. A.; de Blieck-Hogervorst, Jolanda M. A.; Semeins, Cor M.; Zandieh-Doulabi, Behrouz; Helder, Marco N.; Smit, Theo H.; Klein-Nulend, Jenneke

2007-09-01

The catabolic effects of microgravity on mineral metabolism in bone organ cultures might be explained as resulting from an exceptional form of disuse. It is possible that the mechanosensitivity of bone cells is altered under near weightlessness conditions, which likely contributes to disturbed bone metabolism observed in astronauts. In the experiment "FLOW", we tested whether the production of early signaling molecules that are involved in the mechanical load-induced osteogenic response by bone cells is changed under microgravity conditions. FLOW was one of the Biological experiment entries to the Dutch Soyuz Mission "DELTA" (Dutch Expedition for Life Science, Technology and Atmospheric Research). FLOW was flown by the Soyuz craft, launched on April 19, 2004, on its way to the International Space Station. Primary osteocytes, osteoblasts, and periosteal fibroblasts were incubated in plunger boxes, developed by Centre for Concepts in Mechatronics, using plunger activation events for single pulse fluid shear stress stimulations. Due to unforeseen hardware complications, results from in-flight cultures are considered lost. Ground control experiments showed an accumulative increase of NO in medium for osteocytes (as well as for osteoblasts and periosteal fibroblasts). Data from the online-NO sensor showed that the NO produced in medium by osteocytes increased sharply after pulse shear stress stimulations. COX-2 mRNA expression revealed high levels in osteoblasts compared to the other cell types tested. In conclusion, preparations for the FLOW experiment and preliminary ground results indicate that the FLOW setup is viable for a future flight opportunity.

HLA-targeted flow cytometric sorting of blood cells allows separation of pure and viable microchimeric cell populations.

PubMed

Drabbels, Jos J M; van de Keur, Carin; Kemps, Berit M; Mulder, Arend; Scherjon, Sicco A; Claas, Frans H J; Eikmans, Michael

2011-11-10

Microchimerism is defined by the presence of low levels of nonhost cells in a person. We developed a reliable method for separating viable microchimeric cells from the host environment. For flow cytometric cell sorting, HLA antigens were targeted with human monoclonal HLA antibodies (mAbs). Optimal separation of microchimeric cells (present at a proportion as low as 0.01% in artificial mixtures) was obtained with 2 different HLA mAbs, one targeting the chimeric cells and the other the background cells. To verify purity of separated cell populations, flow-sorted fractions of 1000 cells were processed for DNA analysis by HLA-allele-specific and Y-chromosome-directed real-time quantitative PCR assays. After sorting, PCR signals of chimeric DNA markers in the positive fractions were significantly enhanced compared with those in the presort samples, and they were similar to those in 100% chimeric control samples. Next, we demonstrate applicability of HLA-targeted FACS sorting after pregnancy by separating chimeric maternal cells from child umbilical cord mononuclear cells. Targeting allelic differences with anti-HLA mAbs with FACS sorting allows maximal enrichment of viable microchimeric cells from a background cell population. The current methodology enables reliable microchimeric cell detection and separation in clinical specimens.

Visualization study of flow in axial flow inducer.

NASA Technical Reports Server (NTRS)

Lakshminarayana, B.

1972-01-01

A visualization study of the flow through a three ft dia model of a four bladed inducer, which is operated in air at a flow coefficient of 0.065, is reported in this paper. The flow near the blade surfaces, inside the rotating passages, downstream and upstream of the inducer is visualized by means of smoke, tufts, ammonia filament, and lampblack techniques. Flow is found to be highly three dimensional, with appreciable radial velocity throughout the entire passage. The secondary flows observed near the hub and annulus walls agree with qualitative predictions obtained from the inviscid secondary flow theory.

Isolating LacZ-expressing cells from mouse inner ear tissues using flow cytometry.

PubMed

Jan, Taha A; Chai, Renjie; Sayyid, Zahra N; Cheng, Alan G

2011-12-23

Isolation of specific cell types allows one to analyze rare cell populations such as stem/progenitor cells. Such an approach to studying inner ear tissues presents a unique challenge because of the paucity of cells of interest and few transgenic reporter mouse models. Here, we describe a protocol using fluorescence-conjugated probes to selectively label LacZ-positive cells from the neonatal cochleae. The most common underlying pathology of sensorineural hearing loss is the irreversible damage and loss of cochlear sensory hair cells, which are required to transduce sound waves to neural impulses. Recent evidence suggests that the murine auditory and vestibular organs harbor stem/progenitor cells that may have regenerative potential. These findings warrant further investigation, including identifying specific cell types with stem/progenitor cell characteristics. The Wnt signaling pathway has been demonstrated to play a critical role in maintaining stem/progenitor cell populations in several organ systems. We have recently identified Wnt-responsive Axin2-expressing cells in the neonatal cochlea, but their function is largely unknown. To better understand the behavior of these Wnt-responsive cells in vitro, we have developed a method of isolating Axin2-expressing cells from cochleae of Axin2-LacZ reporter mice. Using flow cytometry to isolate Axin2-LacZ positive cells from the neonatal cochleae, we could in turn execute a variety of experiments on live cells to interrogate their behavior as stem/progenitor cells. Here, we describe in detail the steps for the microdissection of neonatal cochlea, dissociation of these tissues, labeling of the LacZ-positive cells using a fluorogenic substrate, and cell sorting. Techniques for dissociating cochleae into single cells and isolating cochlear cells via flow cytometry have been described. We have made modifications to these techniques to establish a novel protocol to isolate LacZ-expressing cells from the neonatal cochlea.

Flow cytometry analysis of hormone receptors on human peripheral blood mononuclear cells to identify stress-induced neuroendocrine effects

NASA Technical Reports Server (NTRS)

Meehan, R. T.

1986-01-01

Understanding the role of circulating peptide hormones in the pathogenesis of space-flight induced disorders would be greatly facilitated by a method which monitors chronic levels of hormones and their effects upon in vivo cell physiology. Single and simultaneous multiparameter flow cytometry analysis was employed to identify subpopulations of mononuclear cells bearing receptors for ACTH, Endorphin, and Somatomedin-C using monoclonal antibodies and monospecific antisera with indirect immunofluorescence. Blood samples were obtained from normal donors and subjects participating in decompression chamber studies (acute stress), medical student academic examination (chronic stress), and a drug study (Dexamethasone). Preliminary results indicate most ACTH and Endorphin receptor positive cells are monocytes and B-cells, exhibit little diurnal variation but the relative percentages of receptor positive cells are influenced by exposure to various stressors and ACTH inhibition. This study demonstrates the capability of flow cytometry analysis to study cell surface hormone receptor regulation which should allow insight into neuroendocrine modulation of the immune and other cellular systems during exposure to stress or microgravity.

Unstructured Euler flow solutions using hexahedral cell refinement

NASA Technical Reports Server (NTRS)

Melton, John E.; Cappuccio, Gelsomina; Thomas, Scott D.

1991-01-01

An attempt is made to extend grid refinement into three dimensions by using unstructured hexahedral grids. The flow solver is developed using the TIGER (topologically Independent Grid, Euler Refinement) as the starting point. The program uses an unstructured hexahedral mesh and a modified version of the Jameson four-stage, finite-volume Runge-Kutta algorithm for integration of the Euler equations. The unstructured mesh allows for local refinement appropriate for each freestream condition, thereby concentrating mesh cells in the regions of greatest interest. This increases the computational efficiency because the refinement is not required to extend throughout the entire flow field.

Design and simulation of novel flow field plate geometry for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Ruan, Hanxia; Wu, Chaoqun; Liu, Shuliang; Chen, Tao

2016-10-01

Bipolar plate is one of the many important components of proton exchange membrane fuel cell (PEMFC) stacks as it supplies fuel and oxidant to the membrane-electrode assembly (MEA), removes water, collects produced current and provides mechanical support for the single cells in the stack. The flow field design of a bipolar plate greatly affects the performance of a PEMFC. It must uniformly distribute the reactant gases over the MEA and prevent product water flooding. This paper aims at improving the fuel cell performance by optimizing flow field designs and flow channel configurations. To achieve this, a novel biomimetic flow channel for flow field designs is proposed based on Murray's Law. Computational fluid dynamics based simulations were performed to compare three different designs (parallel, serpentine and biomimetic channel, respectively) in terms of current density distribution, power density distribution, pressure distribution, temperature distribution, and hydrogen mass fraction distribution. It was found that flow field designs with biomimetic flow channel perform better than that with convectional flow channel under the same operating conditions.

Predicting dynamics and rheology of blood flow: A comparative study of multiscale and low-dimensional models of red blood cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Wenxiao; Fedosov, Dmitry A.; Caswell, Bruce

In this work we compare the predictive capability of two mathematical models for red blood cells (RBCs) focusing on blood flow in capillaries and arterioles. Both RBC models as well as their corresponding blood flows are based on the dissipative particle dynamics (DPD) method, a coarse-grained molecular dynamics approach. The first model employs a multiscale description of the RBC (MS-RBC), with its membrane represented by hundreds or even thousands of DPD-particles connected by springs into a triangular network in combination with out-of-plane elastic bending resistance. Extra dissipation within the network accounts for membrane viscosity, while the characteristic biconcave RBC shapemore » is achieved by imposition of constraints for constant membrane area and constant cell volume. The second model is based on a low-dimensional description (LD-RBC) constructed as a closed torus-like ring of only 10 large DPD colloidal particles. They are connected into a ring by worm-like chain (WLC) springs combined with bending resistance. The LD-RBC model can be fitted to represent the entire range of nonlinear elastic deformations as measured by optical-tweezers for healthy and for infected RBCs in malaria. MS-RBCs suspensions model the dynamics and rheology of blood flow accurately for any size vessel but this approach is computationally expensive above 100 microns. Surprisingly, the much more economical suspensions of LD-RBCs also capture the blood flow dynamics and rheology accurately except for vessels with sizes comparable to RBC diameter. In particular, the LD-RBC suspensions are shown to properly capture the experimental data for the apparent viscosity of blood and its cell-free layer (CFL) in tube flow. Taken together, these findings suggest a hierarchical approach in modeling blood flow in the arterial tree, whereby the MS-RBC model should be employed for capillaries and arterioles below 100 microns, the LD-RBC model for arterioles, and the continuum description for

Naphthol AS-BI (7-bromo-3-hydroxy-2-naphtho-o-anisidine) phosphatase and naphthol AS-BI. beta. -D-glucuronidase in Chinese hamster ovary cells: biochemical and flow cytometric studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolbeare, F.A.; Phares, W.

1979-01-01

Conditions for the biochemical and flow cytometric assay of 7-bromo-3-hydroxy-2-naphtho-o-anisidine phosphatase and ..beta..-D-glucuronidase activities in Chinese hamster ovary cells were studied. In the biochemical assays, the pH optimum for the phosphatase activity was pH 4.6 with a Km of 10/sup -5/ M; the pH optimum for ..beta..-D-glucuronidase activity was pH 5.0 with a Km of 2 x 10/sup -5/ M. For intact cells the derived constants were 3 to 10 times higher. The rate of hydrolysis of both substrates was also examined by flow cytometry. Cellular fluorescence increased linearly for only about 15 min. Diffusion of the fluorescent product probablymore » caused nonlinearity of the fluorescence increase and was demonstrated by mixing cells incubated with substrate with those that had not been incubated. After 15 min, cells that had not been exposed previously to product or substrate contained the fluorescent product. Cells fractionated into size classes by centrifugal elutriation also were analyzed by flow cytometry for ..beta..-D-glucuronidase activity. The activity increased linearly with the increase in cell size corresponding to the progression from G/sub 1/ through S and into G/sub 2/-M phases of the cell cycle.« less

Detection of early changes in lung cell cytology by flow-systems analysis techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steinkamp, J.A.; Hansen, K.M.; Wilson, J.S.

1976-12-01

This report summarizes results of continuing experiments to develop cytological and biochemical indicators for estimating damage to respiratory cells in test animals exposed by inhalation to toxic agents associated with nonnuclear energy production, the specific goal being the application of advanced multiparameter flow-systems technologies to the detection of early atypical cellular changes in lung epithelium. Normal Syrian hamster lung cell samples composed of macrophages, leukocytes, ciliated columnar cells, and epithelial cells were stained with fluorescent dyes specific for different biochemical parameters and were analyzed in liquid suspension as they flowed through a chamber intersecting a laser beam of exciting light.more » Multiple sensors measured the total or two-color fluorescence and light scatter on a cell-by-cell basis. Cellular parameters proportional to optical measurements (i.e., cell size, DNA content, total protein, nonspecific esterase activity, nuclear and cytoplasmic diameters) were displayed as frequency distribution histograms. Lung cell samples were also separated according to various cytological parameters and identified microscopically. The basic operating features of the methodology are discussed briefly, along with specific examples of preliminary results illustrating the initial characterization of exfoliated pulmonary cells from normal hamsters. As the flow technology is adapted further to the analysis of respiratory cells, measurements of changes in physical and biochemical properties as a function of exposure to toxic agents will be performed.« less

Effect of intermittent shear stress on corneal epithelial cells using an in vitro flow culture model.

PubMed

Hampel, Ulrike; Garreis, Fabian; Burgemeister, Fabian; Eßel, Nicole; Paulsen, Friedrich

2018-04-27

The aim of this study was to establish and to evaluate an in vitro model for culturing human telomerase-immortalized corneal epithelial (hTCEpi) cells under adjustable medium flow mimicking the movements of the tear film on the ocular surface. Using an IBIDI pump system, cells were cultured under unidirectional, continuous or oscillating, discontinuous medium flow. Cell surface and cytoskeletal architecture were investigated by scanning electron microscopy and immunofluorescence. Gene expression of e-cadherin, occludin, tight junction protein (TJP), desmoplakin, desmocollin and mucins was investigated by real-time PCR. Protein expression of desmoplakin, TJP, occludin and e-cadherin was analyzed by western blot and localization was detected by immunofluorescence. Rose bengal staining was used to assess mucin (MUC) barrier integrity. MUC1, -4 and -16 proteins were localized by immunofluorescence. Medium flow-induced shear stress dramatically changed cellular morphology of hTCEpi. Cells subjected to discontinuous shear stress displayed the typical flattened, polygonal cell shape of the superficial layer of stratified squamous epithelia. Cell surfaces showed less bulging under shear stress and less extracellular gaps. The mRNA expression of E-cadherin, occludin and TJP were increased under oscillatory medium flow. Desmoplakin and occludin protein were upregulated under oscillatory shear stress. Stress fiber formation was not aligned to flow direction. MUC1, -4, and -16 protein were localized under all culture conditions, a regulation on mRNA expression was not detectable. Rose Bengal uptake was diminished under unidirectional conditions. Our findings suggest that shear stress as it occurs at the ocular surface during blinking exerts marked effects on corneal epithelial cells, such as changes in cellular morphology and expression of cell junctions. The described model may be useful for in vitro investigations of ocular surface epithelia as it represents a much more

An improved method for differentiating cell-bound from internalized particles by imaging flow cytometry.

PubMed

Smirnov, Asya; Solga, Michael D; Lannigan, Joanne; Criss, Alison K

2015-08-01

Recognition, binding, internalization, and elimination of pathogens and cell debris are important functions of professional as well as non-professional phagocytes. However, high-throughput methods for quantifying cell-associated particles and discriminating bound from internalized particles have been lacking. Here we describe a protocol for using imaging flow cytometry to quantify the attached and phagocytosed particles that are associated with a population of cells. Cells were exposed to fluorescent particles, fixed, and exposed to an antibody of a different fluorophore that recognizes the particles. The antibody is added without cell permeabilization, such that the antibody only binds extracellular particles. Cells with and without associated particles were identified by imaging flow cytometry. For each cell with associated particles, a spot count algorithm was employed to quantify the number of extracellular (double fluorescent) and intracellular (single fluorescent) particles per cell, from which the percent particle internalization was determined. The spot count algorithm was empirically validated by examining the fluorescence and phase contrast images acquired by the flow cytometer. We used this protocol to measure binding and internalization of the bacterium Neisseria gonorrhoeae by primary human neutrophils, using different bacterial variants and under different cellular conditions. The results acquired using imaging flow cytometry agreed with findings that were previously obtained using conventional immunofluorescence microscopy. This protocol provides a rapid, powerful method for measuring the association and internalization of any particle by any cell type. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrodynamic lift of vesicles and red blood cells in flow--from Fåhræus & Lindqvist to microfluidic cell sorting.

PubMed

Geislinger, Thomas M; Franke, Thomas

2014-06-01

Hydrodynamic lift forces acting on cells and particles in fluid flow receive ongoing attention from medicine, mathematics, physics and engineering. The early findings of Fåhræus & Lindqvist on the viscosity change of blood with the diameter of capillaries motivated extensive studies both experimentally and theoretically to illuminate the underlying physics. We review this historical development that led to the discovery of the inertial and non-inertial lift forces and elucidate the origins of these forces that are still not entirely clear. Exploiting microfluidic techniques induced a tremendous amount of new insights especially into the more complex interactions between the flow field and deformable objects like vesicles or red blood cells. We trace the way from the investigation of single cell dynamics to the recent developments of microfluidic techniques for particle and cell sorting using hydrodynamic forces. Such continuous and label-free on-chip cell sorting devices promise to revolutionize medical analyses for personalized point-of-care diagnosis. We present the state-of-the-art of different hydrodynamic lift-based techniques and discuss their advantages and limitations. Copyright © 2014 Elsevier B.V. All rights reserved.

Embedded Disposable Functionalized Electrochemical Biosensor with a 3D-Printed Flow Cell for Detection of Hepatic Oval Cells (HOCs).

PubMed

Damiati, Samar; Peacock, Martin; Leonhardt, Stefan; Damiati, Laila; Baghdadi, Mohammed A; Becker, Holger; Kodzius, Rimantas; Schuster, Bernhard

2018-02-14

Hepatic oval cells (HOCs) are considered the progeny of the intrahepatic stem cells that are found in a small population in the liver after hepatocyte proliferation is inhibited. Due to their small number, isolation and capture of these cells constitute a challenging task for immunosensor technology. This work describes the development of a 3D-printed continuous flow system and exploits disposable screen-printed electrodes for the rapid detection of HOCs that over-express the OV6 marker on their membrane. Multiwall carbon nanotube (MWCNT) electrodes have a chitosan film that serves as a scaffold for the immobilization of oval cell marker antibodies (anti-OV6-Ab), which enhance the sensitivity of the biomarker and makes the designed sensor specific for oval cells. The developed sensor can be easily embedded into the 3D-printed flow cell to allow cells to be exposed continuously to the functionalized surface. The continuous flow is intended to increase capture of most of the target cells in the specimen. Contact angle measurements were performed to characterize the nature and quality of the modified sensor surface, and electrochemical measurements (cyclic voltammetry (CV) and square wave voltammetry (SWV)) were performed to confirm the efficiency and selectivity of the fabricated sensor to detect HOCs. The proposed method is valuable for capturing rare cells and could provide an effective tool for cancer diagnosis and detection.

Embedded Disposable Functionalized Electrochemical Biosensor with a 3D-Printed Flow Cell for Detection of Hepatic Oval Cells (HOCs)

PubMed Central

Peacock, Martin; Leonhardt, Stefan; Damiati, Laila; Baghdadi, Mohammed A.; Schuster, Bernhard

2018-01-01

Hepatic oval cells (HOCs) are considered the progeny of the intrahepatic stem cells that are found in a small population in the liver after hepatocyte proliferation is inhibited. Due to their small number, isolation and capture of these cells constitute a challenging task for immunosensor technology. This work describes the development of a 3D-printed continuous flow system and exploits disposable screen-printed electrodes for the rapid detection of HOCs that over-express the OV6 marker on their membrane. Multiwall carbon nanotube (MWCNT) electrodes have a chitosan film that serves as a scaffold for the immobilization of oval cell marker antibodies (anti-OV6-Ab), which enhance the sensitivity of the biomarker and makes the designed sensor specific for oval cells. The developed sensor can be easily embedded into the 3D-printed flow cell to allow cells to be exposed continuously to the functionalized surface. The continuous flow is intended to increase capture of most of the target cells in the specimen. Contact angle measurements were performed to characterize the nature and quality of the modified sensor surface, and electrochemical measurements (cyclic voltammetry (CV) and square wave voltammetry (SWV)) were performed to confirm the efficiency and selectivity of the fabricated sensor to detect HOCs. The proposed method is valuable for capturing rare cells and could provide an effective tool for cancer diagnosis and detection. PMID:29443890

[Preparation of chicken red blood cells for calibration of flow cytometry].

PubMed

Yin, Jian; Zhao, Shutao; Wu, Xiaodong; Wang, Ce; Wu, Yunliang

2013-01-01

To prepare stable chicken red blood cells for the calibration of flow cytometry. The traditional isolation method of chicken red blood cells was modified by incorporating gelatin technique, Ca2+-free HBSS treatment and low-speed centrifugation. The effect of fluorescence staining of the cells was improved by the addition of TritonX-100 to enhance the membrane permeability and Rnase enzymes to disintegrate RNA tiles. The modified method was compared with the traditional method for viability of the freshly isolated cells and the DNA content coefficient of variation (CV) of the fixed cells. Chicken red blood cells obtained by the modified method showed a significantly higher viability than those obtained by the traditional method [(98.5∓3.5)% vs (93.5∓2.7)%, P<0.05]. After glutaraldehyde fixation, the isolated cells with the modified method were stable during the 90-day preservation with a significantly lower CV than the cells obtained by the traditional method [(6.0∓0.3)% to 6.2∓0.4% vs (8.6∓0.5)% to (13.1∓1.4)%, P<0.01]. The chicken red blood cells isolated using the modified method can be applicable for calibration of flow cytometry.

μPIV measurements of two-phase flows of an operated direct methanol fuel cell

NASA Astrophysics Data System (ADS)

Burgmann, Sebastian; Blank, Mirja; Panchenko, Olha; Wartmann, Jens

2013-05-01

In direct methanol fuel cells (DMFCs), two-phase flows appear in the channels of the anode side (CO2 bubbles in a liquid water-methanol environment) as well as of the cathode side (water droplets or films in an ambient air flow). CO2 bubbles or water droplets may almost completely fill the cross-section of a channel. The instantaneous effect of the formation of two-phase flows on the cell performance has not been investigated in detail, yet. In the current project, the micro particle image velocimetry (μPIV) technique is used to elucidate the corresponding flow phenomena on the anode as well as on the cathode side of a DMFC and to correlate those phenomena with the performance of the cell. A single-channel DMFC with optical access at the anode and the cathode side is constructed and assembled that allows for μPIV measurements at both sides as well as a detailed time-resolved cell voltage recording. The appearance and evolution of CO2 bubbles on the anode side is qualitatively and quantitatively investigated. The results clearly indicate that the cell power increases when the free cross-section area of the channel is decreased by huge bubbles. Methanol is forced into the porous gas diffusion layer (GDL) between the channels and the membrane is oxidized to CO2, and hence, the fuel consumption is increased and the cell performance rises. Eventually, a bubble forms a moving slug that effectively cleans the channel from CO2 bubbles on its way downstream. The blockage effect is eliminated; the methanol flow is not forced into the GDL anymore. The remaining amount of methanol in the GDL is oxidized. The cell power decreases until enough CO2 is produced to eventually form bubbles again and the process starts again. On the other hand under the investigated conditions, water on the cathode side only forms liquid films on the channels walls rather than channel-filling droplets. Instantaneous changes of the cell power due to liquid water formation could not be observed. The

Ground based studies of thermocapillary flows in levitated drops

NASA Technical Reports Server (NTRS)

Sadhal, Satwindar Singh; Trinh, Eugene H.

1994-01-01

Analytical studies along with ground-based experiments are presently being carried out in connection with thermocapillary phenomena associated with drops and bubbles in a containerless environment. The effort here focuses on the thermal and the fluid phenomena associated with the local heating of acoustically levitated drops, both at 1-g and at low-g. In particular, the Marangoni effect on drops under conditions of local spot-heating and other types of heating are being studied. With the experiments conducted to date, fairly stable acoustic levitation of drops has been achieved and successful flow visualization by light scattering from smoke particles has been carried out. The results include situations with and without heating. As a preliminary qualitative interpretation of these experimental results, we consider the external flow pattern as a superposition of three discrete circulation cells operating on different spatial scales. The observations of the flow fields also indicate the existence of a steady state torque induced by the streaming flows. The theoretical studies have been concentrated on the analysis of streaming flows in a gaseous medium with the presence of a spherical particle undergoing periodic heating. A matched asymptotic analysis was carried out for small parameters derived from approximations in the high frequency range. The heating frequency being 'in tune' with the acoustic frequency results in a nonzero time-averaged thermal field. This leads to a steady heat flow across the equatorial plane of the sphere.

Myonecrosis in Sickle Cell Anemia: Case Study.

PubMed

Turaga, Lalita Prabha; Boddu, Prajwal; Kipferl, Steve; Basu, Anupam; Yorath, Martin

2017-01-30

BACKGROUND Myonecrosis is one of the more poorly studied, painful manifestations of sickle cell crisis. Medical literature is sparse detailing the manifestations and management of such symptoms. In myonecrosis, red cells containing sickle hemoglobin become rigid, resulting in reduced blood flow and myonecrosis. CASE REPORT We present a case study of a patient in sickle cell crisis with an episode of acute pain and swelling to the intrinsic muscles of the foot as a prominent feature of the crises. Although muscle biopsy is considered the gold standard for the diagnosis of myositis or myonecrosis, a low intensity signal on T1 and high intensity signal on T2 at the affected muscle belly can be as conclusive as imaging studies. In an actively sickling patient any invasive intervention should be avoided as it can result in ischemic necrosis of the tissues, due to interruption of capillary flow in end-arteries. CONCLUSIONS Early recognition is critical in sickle cell disease management, allowing for prompt and aggressive fluid resuscitation which remains a cornerstone in the management of most sickle cell vaso-occlusive crises. In this instance, off loading the extremity and early fluid resuscitation resolved the pain and swelling and prevented myonecrosis.

Myonecrosis in Sickle Cell Anemia: Case Study

PubMed Central

Turaga, Lalita Prabha; Boddu, Prajwal; Kipferl, Steve; Basu, Anupam; Yorath, Martin

2017-01-01

Patient: Male, 27 Final Diagnosis: Myonecrosis of sickle cell anaemia Symptoms: Pain • redness to feet • swelling foot Medication: — Clinical Procedure: MRI Specialty: Podiatry Objective: Rare disease Background: Myonecrosis is one of the more poorly studied, painful manifestations of sickle cell crisis. Medical literature is sparse detailing the manifestations and management of such symptoms. In myonecrosis, red cells containing sickle hemoglobin become rigid, resulting in reduced blood flow and myonecrosis. Case Report: We present a case study of a patient in sickle cell crisis with an episode of acute pain and swelling to the intrinsic muscles of the foot as a prominent feature of the crises. Although muscle biopsy is considered the gold standard for the diagnosis of myositis or myonecrosis, a low intensity signal on T1 and high intensity signal on T2 at the affected muscle belly can be as conclusive as imaging studies. In an actively sickling patient any invasive intervention should be avoided as it can result in ischemic necrosis of the tissues, due to interruption of capillary flow in end-arteries. Conclusions: Early recognition is critical in sickle cell disease management, allowing for prompt and aggressive fluid resuscitation which remains a cornerstone in the management of most sickle cell vaso-occlusive crises. In this instance, off loading the extremity and early fluid resuscitation resolved the pain and swelling and prevented myonecrosis. PMID:28133359

Improved Measurement of B(sub 22) of Macromolecules in a Flow Cell

NASA Technical Reports Server (NTRS)

Wilson, Wilbur; Fanguy, Joseph; Holman, Steven; Guo, Bin

2008-01-01

An improved apparatus has been invented for use in determining the osmotic second virial coefficient of macromolecules in solution. In a typical intended application, the macromolecules would be, more specifically, protein molecules, and the protein solution would be pumped through a flow cell to investigate the physical and chemical conditions that affect crystallization of the protein in question. Some background information is prerequisite to a meaningful description of the novel aspects of this apparatus. A method of determining B22 from simultaneous measurements of the static transmittance (taken as an indication of concentration) and static scattering of light from the same location in a flowing protein solution was published in 2004. The apparatus used to implement the method at that time included a dual-detector flow cell, which had two drawbacks: a) The amount of protein required for analysis of each solution condition was of the order of a milligram - far too large a quantity for a high-throughput analysis system, for which microgram or even nanogram quantities of protein per analysis are desirable. b) The design of flow cell was such that two light sources were used to probe different regions of the flowing solution. Consequently, the apparatus did not afford simultaneous measurements at the same location in the solution and, hence, did not guarantee an accurate determination of B22.

Numerical Simulation of Multiphase Magnetohydrodynamic Flow and Deformation of Electrolyte-Metal Interface in Aluminum Electrolysis Cells

NASA Astrophysics Data System (ADS)

Hua, Jinsong; Rudshaug, Magne; Droste, Christian; Jorgensen, Robert; Giskeodegard, Nils-Haavard

2018-06-01

A computational fluid dynamics based multiphase magnetohydrodynamic (MHD) flow model for simulating the melt flow and bath-metal interface deformation in realistic aluminum reduction cells is presented. The model accounts for the complex physics of the MHD problem in aluminum reduction cells by coupling two immiscible fluids, electromagnetic field, Lorentz force, flow turbulence, and complex cell geometry with large length scale. Especially, the deformation of bath-metal interface is tracked directly in the simulation, and the condition of constant anode-cathode distance (ACD) is maintained by moving anode bottom dynamically with the deforming bath-metal interface. The metal pad deformation and melt flow predicted by the current model are compared to the predictions using a simplified model where the bath-metal interface is assumed flat. The effects of the induced electric current due to fluid flow and the magnetic field due to the interior cell current on the metal pad deformation and melt flow are investigated. The presented model extends the conventional simplified box model by including detailed cell geometry such as the ledge profile and all channels (side, central, and cross-channels). The simulations show the model sensitivity to different side ledge profiles and the cross-channel width by comparing the predicted melt flow and metal pad heaving. In addition, the model dependencies upon the reduction cell operation conditions such as ACD, current distribution on cathode surface and open/closed channel top, are discussed.

Ligament flow during drop-on-demand inkjet printing of bioink containing living cells

NASA Astrophysics Data System (ADS)

Zhang, Mengyun; Krishnamoorthy, Srikumar; Song, Hongtao; Zhang, Zhengyi; Xu, Changxue

2017-03-01

Organ printing utilizes tissue spheroids or filaments as building blocks to fabricate three-dimensional (3D) functional tissues and organs based on a layer-by-layer manufacturing mechanism. These fabricated tissues and organs are envisioned as alternatives to replace the damaged human tissues and organs, which is emerging as a promising solution to solve the organ donor shortage problem being faced all over the world. Inkjetting, one of the key technologies in organ printing, has been widely developed because of its moderate fabrication cost, good process controllability, and scale-up potentials. There are several key steps towards inkjet-based organ printing: generation of droplets from bioink, fabrication of 3D cellular structures, and post-printing tissue fusion and maturation. The droplet formation process is the first step, affecting the overall feasibility of the envisioned organ printing technology. This paper focuses on the ligament flow of the droplet formation process during inkjet printing of bioink containing living cells and its corresponding effect on post-printing cell viability and cell distribution. It is found that (1) two types of ligament flow are observed: at 30 V (Type I), the ligament flow has two different directions at the locations near the nozzle orifice and the forming droplet; at 60 V (Type II), the ligament flow directions are the same at both locations; (2) compared to Type II, fewer cells are ejected into the primary droplets in Type I, because some cells move back into the nozzle driven by the ligament flow in the positive z direction; and (3) cell viability in both Type I and Type II is around 90% without a significant difference. The resulting knowledge will benefit precise control of printing dynamics during inkjet printing of viscoelastic bioink for 3D biofabrication applications.

Rapid Assessment of Genotoxicity by Flow Cytometric Detection of Cell Cycle Alterations.

PubMed

Bihari, Nevenka

2017-01-01

Flow cytometry is a convenient method for the determination of genotoxic effects of environmental pollution and can reveal genotoxic compounds in unknown environmental mixtures. It is especially suitable for the analyses of large numbers of samples during monitoring programs. The speed of detection is one of the advantages of this technique which permits the acquisition of 10 4 -10 5 cells per sample in 5 min. This method can rapidly detect cell cycle alterations resulting from DNA damage. The outcome of such an analysis is a diagram of DNA content across the cell cycle which indicates cell proliferation, G 2 arrests, G 1 delays, apoptosis, and ploidy.Here, we present the flow cytometric procedure for rapid assessment of genotoxicity via detection of cell cycle alterations. The described protocol simplifies the analysis of genotoxic effects in marine environments and is suitable for monitoring purposes. It uses marine mussel cells in the analysis and can be adapted to investigations on a broad range of marine invertebrates.

Tracking protein aggregation and mislocalization in cells with flow cytometry.

PubMed

Ramdzan, Yasmin M; Polling, Saskia; Chia, Cheryl P Z; Ng, Ivan H W; Ormsby, Angelique R; Croft, Nathan P; Purcell, Anthony W; Bogoyevitch, Marie A; Ng, Dominic C H; Gleeson, Paul A; Hatters, Danny M

2012-03-18

We applied pulse-shape analysis (PulSA) to monitor protein localization changes in mammalian cells by flow cytometry. PulSA enabled high-throughput tracking of protein aggregation, translocation from the cytoplasm to the nucleus and trafficking from the plasma membrane to the Golgi as well as stress-granule formation. Combining PulSA with tetracysteine-based oligomer sensors in a cell model of Huntington's disease enabled further separation of cells enriched with monomers, oligomers and inclusion bodies.

Mimicking the Interfacial Dynamics of Flowing White Blood Cells

NASA Astrophysics Data System (ADS)

Santore, Maria

2015-03-01

The rolling of particles on surfaces, facilitated by hydrodynamic forces combined with localized surface interactions of the appropriate strengths, spatial arrangements, and ranges, is a technologically useful means of transporting and manipulating particles. One's intuition for the rolling of a marble or a car tire cannot be extrapolated down to microparticle length scales because the microparticle interactions are dominated by electrostatic, van der Waals, and hydrogen bonding interactions rather than a friction that depends on an imposed normal force. Indeed, our microparticle rolling systems are inspired by the rolling of white blood cells on the inner walls of venules as part of the innate immune response: Selectin molecules engage with their counterparts on the opposing surfaces to slow cell motion relative to that for freely flowing cells. In the resulting rolling signature, ligand-receptor binding and crack closing on the front of the cell are balanced with molecular dis-bonding and crack opening at the rear. The contact region is relatively static, allowing other interactions (for instance signaling) to occur for a finite duration. Thus, achieving particle rolling in synthetic systems is important because it facilitates particle-surface interactions in a continuous nonfouling fashion where the contact surface is continually renewed. In developing a synthetic model for this system, we employ polymers to modify flowing particles and /or planar collectors, producing heterogeneous interfaces which can support rolling or produce other motion signatures such as skipping, arrest, or free flow. We identify, in the synthetic system, combinations of variables that produce rolling and demonstrate how the distinction between rolling and arrest is not a simple matter of the adhesion strength between the particles and the collector. Rolling is a cooperative process and the coordination of binding in one location with dis-bonding in another requires appropriate length

Understanding leachate flow in municipal solid waste landfills by combining time-lapse ERT and subsurface flow modelling - Part I: Analysis of infiltration shape on two different waste deposit cells.

PubMed

Audebert, M; Clément, R; Moreau, S; Duquennoi, C; Loisel, S; Touze-Foltz, N

2016-09-01

Landfill bioreactors are based on an acceleration of in-situ waste biodegradation by performing leachate recirculation. To quantify the water content and to evaluate the leachate injection system, in-situ methods are required to obtain spatially distributed information, usually electrical resistivity tomography (ERT). In a previous study, the MICS (multiple inversions and clustering strategy) methodology was proposed to improve the hydrodynamic interpretation of ERT results by a precise delimitation of the infiltration area. In this study, MICS was applied on two ERT time-lapse data sets recorded on different waste deposit cells in order to compare the hydrodynamic behaviour of leachate flow between the two cells. This comparison is based on an analysis of: (i) the volume of wetted waste assessed by MICS and the wetting rate, (ii) the infiltration shapes and (iii) the pore volume used by the leachate flow. This paper shows that leachate hydrodynamic behaviour is comparable from one waste deposit cell to another with: (i) a high leachate infiltration speed at the beginning of the infiltration, which decreases with time, (ii) a horizontal anisotropy of the leachate infiltration shape and (iii) a very small fraction of the pore volume used by the leachate flow. This hydrodynamic information derived from MICS results can be useful for subsurface flow modelling used to predict leachate flow at the landfill scale. Copyright © 2016 Elsevier Ltd. All rights reserved.

An Improved Flow Cytometry Method For Precise Quantitation Of Natural-Killer Cell Activity

NASA Technical Reports Server (NTRS)

Crucian, Brian; Nehlsen-Cannarella, Sandra; Sams, Clarence

2006-01-01

The ability to assess NK cell cytotoxicity using flow cytometry has been previously described and can serve as a powerful tool to evaluate effector immune function in the clinical setting. Previous methods used membrane permeable dyes to identify target cells. The use of these dyes requires great care to achieve optimal staining and results in a broad spectral emission that can make multicolor cytometry difficult. Previous methods have also used negative staining (the elimination of target cells) to identify effector cells. This makes a precise quantitation of effector NK cells impossible due to the interfering presence of T and B lymphocytes, and the data highly subjective to the variable levels of NK cells normally found in human peripheral blood. In this study an improved version of the standard flow cytometry assay for NK activity is described that has several advantages of previous methods. Fluorescent antibody staining (CD45FITC) is used to positively identify target cells in place of membranepermeable dyes. Fluorescent antibody staining of target cells is less labor intensive and more easily reproducible than membrane dyes. NK cells (true effector lymphocytes) are also positively identified by fluorescent antibody staining (CD56PE) allowing a simultaneous absolute count assessment of both NK cells and target cells. Dead cells are identified by membrane disruption using the DNA intercalating dye PI. Using this method, an exact NK:target ratio may be determined for each assessment, including quantitation of NK target complexes. Backimmunoscatter gating may be used to track live vs. dead Target cells via scatter properties. If desired, NK activity may then be normalized to standardized ratios for clinical comparisons between patients, making the determination of PBMC counts or NK cell percentages prior to testing unnecessary. This method provides an exact cytometric determination of NK activity that highly reproducible and may be suitable for routine use in the

Tracking by flow cytometry antigen-specific follicular helper T cells in wild-type animals after protein vaccination.

PubMed

Chakarov, Svetoslav; Fazilleau, Nicolas

2015-01-01

Flow cytometry is a valuable technology used in immunology to characterize and enumerate the different cell subpopulations specific for a nonself-antigen in the context of an ongoing immune response. Among them, follicular helper T cells are the cognate regulators of B cells in secondary lymphoid tissues. Thus, tracking them is of high interest especially in the context of protein vaccination. For this purpose, transgenic antigen-receptor mouse models have been largely used. It is now clear that transgenic models are not always the best means to study the dynamics of the immune response since they can modify the response. In this chapter, we describe how to track endogenous antigen-specific follicular helper T cells by flow cytometry after protein vaccination in nonmodified wild-type animals, which ultimately provides a comprehensive way to enumerate, characterize, and isolate these particular cells in vivo.

Co-flow anode/cathode supply heat exchanger for a solid-oxide fuel cell assembly

DOEpatents

Haltiner, Jr., Karl J.; Kelly, Sean M.

2005-11-22

In a solid-oxide fuel cell assembly, a co-flow heat exchanger is provided in the flow paths of the reformate gas and the cathode air ahead of the fuel cell stack, the reformate gas being on one side of the exchanger and the cathode air being on the other. The reformate gas is at a substantially higher temperature than is desired in the stack, and the cathode gas is substantially cooler than desired. In the co-flow heat exchanger, the temperatures of the reformate and cathode streams converge to nearly the same temperature at the outlet of the exchanger. Preferably, the heat exchanger is formed within an integrated component manifold (ICM) for a solid-oxide fuel cell assembly.

Interstitial Fluid Flow Increases Hepatocellular Carcinoma Cell Invasion through CXCR4/CXCL12 and MEK/ERK Signaling

PubMed Central

2015-01-01

Hepatocellular carcinoma (HCC) is the most common form of liver cancer (~80%), and it is one of the few cancer types with rising incidence in the United States. This highly invasive cancer is very difficult to detect until its later stages, resulting in limited treatment options and low survival rates. There is a dearth of knowledge regarding the mechanisms associated with the effects of biomechanical forces such as interstitial fluid flow (IFF) on hepatocellular carcinoma invasion. We hypothesized that interstitial fluid flow enhanced hepatocellular carcinoma cell invasion through chemokine-mediated autologous chemotaxis. Utilizing a 3D in vitro invasion assay, we demonstrated that interstitial fluid flow promoted invasion of hepatocellular carcinoma derived cell lines. Furthermore, we showed that autologous chemotaxis influences this interstitial fluid flow-induced invasion of hepatocellular carcinoma derived cell lines via the C-X-C chemokine receptor type 4 (CXCR4)/C-X-C motif chemokine 12 (CXCL12) signaling axis. We also demonstrated that mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling affects interstitial fluid flow-induced invasion; however, this pathway was separate from CXCR4/CXCL12 signaling. This study demonstrates, for the first time, the potential role of interstitial fluid flow in hepatocellular carcinoma invasion. Uncovering the mechanisms that control hepatocellular carcinoma invasion will aid in enhancing current liver cancer therapies and provide better treatment options for patients. PMID:26560447

Hydrodynamics in Cell Studies

PubMed Central

2018-01-01

Hydrodynamic phenomena are ubiquitous in living organisms and can be used to manipulate cells or emulate physiological microenvironments experienced in vivo. Hydrodynamic effects influence multiple cellular properties and processes, including cell morphology, intracellular processes, cell–cell signaling cascades and reaction kinetics, and play an important role at the single-cell, multicellular, and organ level. Selected hydrodynamic effects can also be leveraged to control mechanical stresses, analyte transport, as well as local temperature within cellular microenvironments. With a better understanding of fluid mechanics at the micrometer-length scale and the advent of microfluidic technologies, a new generation of experimental tools that provide control over cellular microenvironments and emulate physiological conditions with exquisite accuracy is now emerging. Accordingly, we believe that it is timely to assess the concepts underlying hydrodynamic control of cellular microenvironments and their applications and provide some perspective on the future of such tools in in vitro cell-culture models. Generally, we describe the interplay between living cells, hydrodynamic stressors, and fluid flow-induced effects imposed on the cells. This interplay results in a broad range of chemical, biological, and physical phenomena in and around cells. More specifically, we describe and formulate the underlying physics of hydrodynamic phenomena affecting both adhered and suspended cells. Moreover, we provide an overview of representative studies that leverage hydrodynamic effects in the context of single-cell studies within microfluidic systems. PMID:29420889

Some potential blood flow experiments for space

NASA Technical Reports Server (NTRS)

Cokelet, G. R.; Meiselman, H. J.; Goldsmith, H. L.

1979-01-01

Blood is a colloidal suspension of cells, predominantly erythrocytes, (red cells) in an aqueous solution called plasma. Because the red cells are more dense than the plasma, and because they tend to aggregate, erythrocyte sedimentation can be significant when the shear stresses in flowing blood are small. This behavior, coupled with equipment restrictions, has prevented certain definitive fluid mechanical studies from being performed with blood in ground-based experiments. Among such experiments, which could be satisfactorily performed in a microgravity environment, are the following: (1) studies of blood flow in small tubes, to obtain pressure-flow rate relationships, to determine if increased red cell aggregation can be an aid to blood circulation, and to determine vessel entrance lengths, and (2) studies of blood flow through vessel junctions (bifurcations), to obtain information on cell distribution in downstream vessels of (arterial) bifurcations, and to test flow models of stratified convergent blood flows downstream from (venous) bifurcations.

Counter-rotational cell flows drive morphological and cell fate asymmetries in mammalian hair follicles.

PubMed

Cetera, Maureen; Leybova, Liliya; Joyce, Bradley; Devenport, Danelle

2018-05-01

Organ morphogenesis is a complex process coordinated by cell specification, epithelial-mesenchymal interactions and tissue polarity. A striking example is the pattern of regularly spaced, globally aligned mammalian hair follicles, which emerges through epidermal-dermal signaling and planar polarized morphogenesis. Here, using live-imaging, we discover that developing hair follicles polarize through dramatic cell rearrangements organized in a counter-rotational pattern of cell flows. Upon hair placode induction, Shh signaling specifies a radial pattern of progenitor fates that, together with planar cell polarity, induce counter-rotational rearrangements through myosin and ROCK-dependent polarized neighbour exchanges. Importantly, these cell rearrangements also establish cell fate asymmetry by repositioning radial progenitors along the anterior-posterior axis. These movements concurrently displace associated mesenchymal cells, which then signal asymmetrically to maintain polarized cell fates. Our results demonstrate how spatial patterning and tissue polarity generate an unexpected collective cell behaviour that in turn, establishes both morphological and cell fate asymmetry.

Subtle exchange model of flow depended on the blood cell shape to enhance the micro-circulation in capillary

NASA Astrophysics Data System (ADS)

Chan, Iatneng

2012-02-01

In general the exchange of gases or other material in capillary system is conceptualized by the diffusion effect. But in this model, we investigate a micro-flow pattern by simulation and computation on a micro-exchange model in which the blood cell is a considered factor, especially on its shape. It shows that the cell benefits the circulation while it is moving in the capillary. In the study, the flow detail near the cell surface is mathematically analyzed, such that the Navier-Stokes equations are applied and the viscous factor is also briefly considered. For having a driven force to the motion of micro-circulation, a breathing mode is suggested to approximately compute on the flow rate in the blood capillary during the transfer of cell. The rate is also used to estimate the enhancement to the circulation in additional to the outcome of diffusion. Moreover in the research, the shape change of capillary wall under pressure influence is another element in the beginning calculation for the effect in the assistance to cell motion.

Quantum dot interactions and flow effects in angiogenic zebrafish (Danio rerio) vessels and human endothelial cells.

PubMed

Jiang, Xiao-Yu; Sarsons, Christopher D; Gomez-Garcia, M Juliana; Cramb, David T; Rinker, Kristina D; Childs, Sarah J

2017-04-01

Nanoparticle (NP) interactions with biological tissues are affected by the size, shape and surface chemistry of the NPs. Here we use in vivo (zebrafish) and in vitro (HUVEC) models to investigate association of quantum dots (QDs) with endothelial cells and the effect of fluid flow. After injection into the developing zebrafish, circulating QDs associate with endothelium and penetrate surrounding tissue parenchyma over time. Amino-functionalized QDs cluster, interact with cells, and clear more rapidly than carboxy-functionalized QDs in vivo, highlighting charge influences. QDs show stronger accumulation in slow-flowing, small caliber venous vessels than in fast-flowing high caliber arterial vessels. Parallel-plate flow experiments with HUVEC support these findings, showing reduced QD-EC association with increasing flow. In vivo, flow arrest after nanoparticle injection still results in venous accumulation at 18 h. Overall our results suggest that both QD charge and blood flow modulate particle-endothelial cell interactions. Copyright © 2016 Elsevier Inc. All rights reserved.

A microfluidic device for study of the effect of tumor vascular structures on the flow field and HepG2 cellular flow behaviors.

PubMed

Ke, Ming; Cai, Shaoxi; Zou, Misha; Zhao, Yi; Li, Bo; Chen, Sijia; Chen, Longcong

2018-01-29

To build a microfluidic device with various morphological features of the tumor vasculature for study of the effects of tumor vascular structures on the flow field and tumor cellular flow behaviors. The designed microfluidic device was able to approximatively simulate the in vivo structures of tumor vessels and the flow within it. In this models, the influences of the angle of bifurcation, the number of branches, and the narrow channels on the flow field and the influence of vorticity on the retention of HepG2 cells were significant. Additionally, shear stress below physiological conditions of blood circulation has considerable effect on the formation of the lumen-like structures (LLSs) of HepG2 cells. These results can provide some data and reference in the understanding of the interaction between hemorheological properties and tumor vascular structures in solid tumors. Copyright © 2018. Published by Elsevier Inc.

Magnetic manipulation of particles and cells in ferrofluid flow through straight microchannels using two magnets

NASA Astrophysics Data System (ADS)

Zeng, Jian

Microfluidic devices have been increasingly used in the past two decades for particle and cell manipulations in many chemical and biomedical applications. A variety of force fields have been demonstrated to control particle and cell transport in these devices including electric, magnetic, acoustic, and optical forces etc. Among these particle handling techniques, the magnetic approach provides clear advantages over others such as low cost, noninvasive, and free of fluid heating issues. However, the current knowledge of magnetic control of particle transport is still very limited, especially lacking is the handling of diamagnetic particle. This thesis is focused on the magnetic manipulation of diamagnetic particles and cells in ferrofluid flow through the use of a pair of permanent magnets. By varying the configuration of the two magnets, diverse operations of particles and cells is implemented in a straight microchannel that can potentially be integrated into lab-on-a-chip devices for various applications. First, an approach for embedding two, symmetrically positioned, repulsive permanent magnets about a straight rectangular microchannel in a PDMS-based microfluidic device is developed for particle focusing. Focusing particles and cells into a tight stream is often required in order for continuous detection, counting, and sorting. The closest distance between the magnets is limited only by the size of the magnets involved in the fabrication process. The device is used to implement and investigate the three-dimensional magnetic focusing of polystyrene particles in ferrofluid microflow with both top-view and side-view visualizations. The effects of flow speed and particle size on the particle focusing effectiveness are studied. This device is also applied to magnetically focus yeast cells in ferrofluid, which proves to be biocompatible as verified by cell viability test. In addition, an analytical model is developed and found to be able to predict the experimentally

Flow Cytometric Methods for Circulating Tumor Cell Isolation and Molecular Analysis.

PubMed

Bhagwat, Neha; Carpenter, Erica L

2017-01-01

Circulating tumor cells provide a non-invasive source of tumor material that can be valuable at all stages of disease management, including screening and early diagnosis, monitoring response to therapy, identifying therapeutic targets, and assessing development of drug resistance. Cells isolated from the blood of cancer patients can be used for phenotypic analysis, tumor genotyping, transcriptional profiling, as well as for ex vivo culture of isolated cells. There are a variety of novel technologies currently being developed for the detection and analysis of rare cells in circulation of cancer patients. Flow cytometry is a powerful cell analysis platform that is increasingly being used in this field of study due to its relatively high throughput and versatility with respect to the large number of commercially available antibodies and fluorescent probes available to translational and clinical researchers. More importantly, it offers the ability to easily recover viable cells with high purity that are suitable for downstream molecular analysis, thus making it an attractive technology for cancer research and as a diagnostic tool.

Fluorescent Cell Barcoding for Multiplex Flow Cytometry

PubMed Central

Krutzik, Peter O.; Clutter, Matthew R.; Trejo, Angelica; Nolan, Garry P.

2011-01-01

Fluorescent Cell Barcoding (FCB) enables high throughput, i.e. high content flow cytometry by multiplexing samples prior to staining and acquisition on the cytometer. Individual cell samples are barcoded, or labeled, with unique signatures of fluorescent dyes so that they can be mixed together, stained, and analyzed as a single sample. By mixing samples prior to staining, antibody consumption is typically reduced 10 to 100-fold. In addition, data robustness is increased through the combination of control and treated samples, which minimizes pipetting error, staining variation, and the need for normalization. Finally, speed of acquisition is enhanced, enabling large profiling experiments to be run with standard cytometer hardware. In this unit, we outline the steps necessary to apply the FCB method to cell lines as well as primary peripheral blood samples. Important technical considerations such as choice of barcoding dyes, concentrations, labeling buffers, compensation, and software analysis are discussed. PMID:21207359

Pinched flow coupled shear-modulated inertial microfluidics for high-throughput rare blood cell separation.

PubMed

Bhagat, Ali Asgar S; Hou, Han Wei; Li, Leon D; Lim, Chwee Teck; Han, Jongyoon

2011-06-07

Blood is a highly complex bio-fluid with cellular components making up >40% of the total volume, thus making its analysis challenging and time-consuming. In this work, we introduce a high-throughput size-based separation method for processing diluted blood using inertial microfluidics. The technique takes advantage of the preferential cell focusing in high aspect-ratio microchannels coupled with pinched flow dynamics for isolating low abundance cells from blood. As an application of the developed technique, we demonstrate the isolation of cancer cells (circulating tumor cells (CTCs)) spiked in blood by exploiting the difference in size between CTCs and hematologic cells. The microchannel dimensions and processing parameters were optimized to enable high throughput and high resolution separation, comparable to existing CTC isolation technologies. Results from experiments conducted with MCF-7 cells spiked into whole blood indicate >80% cell recovery with an impressive 3.25 × 10(5) fold enrichment over red blood cells (RBCs) and 1.2 × 10(4) fold enrichment over peripheral blood leukocytes (PBL). In spite of a 20× sample dilution, the fast operating flow rate allows the processing of ∼10(8) cells min(-1) through a single microfluidic device. The device design can be easily customized for isolating other rare cells from blood including peripheral blood leukocytes and fetal nucleated red blood cells by simply varying the 'pinching' width. The advantage of simple label-free separation, combined with the ability to retrieve viable cells post enrichment and minimal sample pre-processing presents numerous applications for use in clinical diagnosis and conducting fundamental studies.

Flow-injection analysis of catecholamine secretion from bovine adrenal medulla cells on microbeads.

PubMed

Herrera, M; Kao, L S; Curran, D J; Westhead, E W

1985-01-01

Bovine adrenal medullary cells have been cultured on microbeads which are placed in a low-volume flow system for measurements of stimulation-response parameters. Electronically controlled stream switching allows stimulation of cells with pulse lengths from 1 s to many minutes; pulses may be repeated indefinitely. Catecholamines secreted are detected by an electrochemical detector downstream from the cells. This flow-injection analysis technique provides a new level of sensitivity and precision for measurement of kinetic parameters of secretion. A manual injection valve allows stimulation by higher levels of stimulant in the presence of constant low levels of stimulant. Such experiments show interesting differences between the effects of K+ and acetylcholine on cells partially desensitized to acetylcholine.

Where Do All the Phytoplankton Go? Challenges in Keeping Track of Viable Cells in Phytoplankton Communities Using Flow Cytometry and Cell Staining

NASA Astrophysics Data System (ADS)

Simmons, L. J.; Fobbe, D. J.; Berges, J. A.

2016-02-01

Understanding the dynamics of phytoplankton communities has traditionally focused on differences in growth and related processes among taxa. It is now appreciated that differences in mortality could be equally important in contributing to these dynamics. Studying mortality in communities is difficult, especially on relevant time scales, which could be as short as hours to days. Flow cytometry can potentially provide solutions, because it can allow discrimination of different taxa, and when combined with staining, distinguish live and dead cells. We applied flow cytometry and staining to phytoplankton communities in a model system: a small, well-studied, urban pond in southeastern Wisconsin. Using flow cytometry, it was possible to resolve up to six dominant taxa (most <37 µm) and track them through an annual cycle. However, the axes traditionally used, forward scatter (FSC, related to cell size) and red fluorescence (FL3, related to chlorophyll a content) offered poor discrimination. Addition of orange fluorescence (FL2, traditionally related to phycobilipigments) and side scatter (SSC, related to cell surface characteristics) improved separation of taxa, but reproducibility (i.e. the specific position of the taxa on axes) was also more sensitive to environmental variation in the case of the fluorescence parameters. Dead cells could be distinguished by green fluorescence (FL1, using SYTOX Green©), but the stain also affected other fluorescence channels, requiring compensation. Correlations of numbers of dead cells with environmental factors (e.g. temperature, nutrient concentrations, irradiance) were generally poor, suggesting the greater importance of biotic versus abiotic variables in community mortality dynamics. Ongoing work is focusing on the effects of viral pathogens, grazing and allelopathic interactions using experimental manipulations and individual-based modeling.

All-Fullerene-Based Cells for Nonaqueous Redox Flow Batteries.

PubMed

Friedl, Jochen; Lebedeva, Maria A; Porfyrakis, Kyriakos; Stimming, Ulrich; Chamberlain, Thomas W

2018-01-10

Redox flow batteries have the potential to revolutionize our use of intermittent sustainable energy sources such as solar and wind power by storing the energy in liquid electrolytes. Our concept study utilizes a novel electrolyte system, exploiting derivatized fullerenes as both anolyte and catholyte species in a series of battery cells, including a symmetric, single species system which alleviates the common problem of membrane crossover. The prototype multielectron system, utilizing molecular based charge carriers, made from inexpensive, abundant, and sustainable materials, principally, C and Fe, demonstrates remarkable current and energy densities and promising long-term cycling stability.

The use of flow cytometry to examine calcium signalling by TRPV1 in mixed cell populations.

PubMed

Assas, Bakri M; Abdulaal, Wesam H; Wakid, Majed H; Zakai, Haytham A; Miyan, J; Pennock, J L

2017-06-15

Flow cytometric analysis of calcium mobilisation has been in use for many years in the study of specific receptor engagement or isolated cell:cell communication. However, calcium mobilisation/signaling is key to many cell functions including apoptosis, mobility and immune responses. Here we combine multiplex surface staining of whole spleen with Indo-1 AM to visualise calcium mobilisation and examine calcium signaling in a mixed immune cell culture over time. We demonstrate responses to a TRPV1 agonist in distinct cell subtypes without the need for cell separation. Multi parameter staining alongside Indo-1 AM to demonstrate calcium mobilization allows the study of real time calcium signaling in a complex environment. Copyright © 2017. Published by Elsevier Inc.

Continuous Flow Deformability-Based Separation of Circulating Tumor Cells Using Microfluidic Ratchets.

PubMed

Park, Emily S; Jin, Chao; Guo, Quan; Ang, Richard R; Duffy, Simon P; Matthews, Kerryn; Azad, Arun; Abdi, Hamidreza; Todenhöfer, Tilman; Bazov, Jenny; Chi, Kim N; Black, Peter C; Ma, Hongshen

2016-04-13

Circulating tumor cells (CTCs) offer tremendous potential for the detection and characterization of cancer. A key challenge for their isolation and subsequent analysis is the extreme rarity of these cells in circulation. Here, a novel label-free method is described to enrich viable CTCs directly from whole blood based on their distinct deformability relative to hematological cells. This mechanism leverages the deformation of single cells through tapered micrometer scale constrictions using oscillatory flow in order to generate a ratcheting effect that produces distinct flow paths for CTCs, leukocytes, and erythrocytes. A label-free separation of circulating tumor cells from whole blood is demonstrated, where target cells can be separated from background cells based on deformability despite their nearly identical size. In doping experiments, this microfluidic device is able to capture >90% of cancer cells from unprocessed whole blood to achieve 10(4) -fold enrichment of target cells relative to leukocytes. In patients with metastatic castration-resistant prostate cancer, where CTCs are not significantly larger than leukocytes, CTCs can be captured based on deformability at 25× greater yield than with the conventional CellSearch system. Finally, the CTCs separated using this approach are collected in suspension and are available for downstream molecular characterization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamics of polymers in elongational flow studied by the neutron spin-echo technique

NASA Astrophysics Data System (ADS)

Rheinstädter, Maikel C.; Sattler, Rainer; Häußler, Wolfgang; Wagner, Christian

2010-09-01

The nanoscale fluctuation dynamics of semidilute high molecular weight polymer solutions of polyethylenoxide (PEO) in D 2O under non-equilibrium flow conditions were studied by the neutron spin-echo technique. The sample cell was in contraction flow geometry and provided a pressure driven flow with a high elongational component that stretched the polymers most efficiently. Neutron scattering experiments in dilute polymer solutions are challenging because of the low polymer concentration and corresponding small quasi-elastic signals. A relaxation process with relaxation times of about 10 ps was observed, which shows anisotropic dynamics with applied flow.

Endothelial Progenitor Cells (EPC) Count by Multicolor Flow Cytometry in Healthy Individuals and Diabetes Mellitus (DM) Patients.

PubMed

Falay, Mesude; Aktas, Server

2016-11-01

The present study aimed to determine circulating Endothelial Progenitor Cell (EPC) counts by multicolor flow cytometry in healthy individuals and diabetic subjects by means of forming an analysis procedure using a combination of monoclonal antibodies (moAbs), which would correctly detect the circulating EPC count. The circulating EPC count was detected in 40 healthy individuals (20 Female, 20 Male; age range: 26 - 50 years) and 30 Diabetes Mellitus (DM) patients (15 Female, 15 Male; age range: 42 - 55) by multicolor flow cytometry (FCM) in a single-tube panel consisting of 5 CD45/CD31/CD34/CD309/ SYTO® and 16 monoclonal antibodies. Circulating EPC count was 11.33 (7.89 - 15.25) cells/µL in the healthy control group and 4.80 (0.70 - 10.85) cells/µL in the DM group. EPC counts were significantly lower in DM cases that developed coronary artery disease (53.3%) as compared to those that did not (p < 0.001). In the present study, we describe a method that identifies circulating EPC counts by multicolor flow cytometry in a single tube and determines the circulating EPC count in healthy individuals. This is the first study conducted on EPC count in Turkish population. We think that the EPC count found in the present study will be a guide for future studies.

Quantitative analysis of optical properties of flowing blood using a photon-cell interactive Monte Carlo code: effects of red blood cells' orientation on light scattering.

PubMed

Sakota, Daisuke; Takatani, Setsuo

2012-05-01

Optical properties of flowing blood were analyzed using a photon-cell interactive Monte Carlo (pciMC) model with the physical properties of the flowing red blood cells (RBCs) such as cell size, shape, refractive index, distribution, and orientation as the parameters. The scattering of light by flowing blood at the He-Ne laser wavelength of 632.8 nm was significantly affected by the shear rate. The light was scattered more in the direction of flow as the flow rate increased. Therefore, the light intensity transmitted forward in the direction perpendicular to flow axis decreased. The pciMC model can duplicate the changes in the photon propagation due to moving RBCs with various orientations. The resulting RBC's orientation that best simulated the experimental results was with their long axis perpendicular to the direction of blood flow. Moreover, the scattering probability was dependent on the orientation of the RBCs. Finally, the pciMC code was used to predict the hematocrit of flowing blood with accuracy of approximately 1.0 HCT%. The photon-cell interactive Monte Carlo (pciMC) model can provide optical properties of flowing blood and will facilitate the development of the non-invasive monitoring of blood in extra corporeal circulatory systems.

An All-vanadium Continuous-flow Photoelectrochemical Cell for Extending State-of-charge in Solar Energy Storage.

PubMed

Wei, Zi; Shen, Yi; Liu, Dong; Liu, Fuqiang

2017-04-04

Greater levels of solar energy storage provide an effective solution to the inherent nature of intermittency, and can substantially improve reliability, availability, and quality of the renewable energy source. Here we demonstrated an all-vanadium (all-V) continuous-flow photoelectrochemical storage cell (PESC) to achieve efficient and high-capacity storage of solar energy, through improving both photocurrent and photocharging depth. It was discovered that forced convective flow of electrolytes greatly enhanced the photocurrent by 5 times comparing to that with stagnant electrolytes. Electrochemical impedance spectroscopy (EIS) study revealed a great reduction of charge transfer resistance with forced convective flow of electrolytes as a result of better mass transport at U-turns of the tortuous serpentine flow channel of the cell. Taking advantage of the improved photocurrent and diminished charge transfer resistance, the all-V continuous-flow PESC was capable of producing ~20% gain in state of charge (SOC) under AM1.5 illumination for ca. 1.7 hours without any external bias. This gain of SOC was surprisingly three times more than that with stagnant electrolytes during a 25-hour period of photocharge.

DPD simulation on the dynamics of a healthy and infected red blood cell in flow through a constricted channel

NASA Astrophysics Data System (ADS)

Hoque, Sazid Zamal; Anand, D. Vijay; Patnaik, B. S. V.

2017-11-01

The state of the red blood cell (either healthy or infected RBC) will influence its deformation dynamics. Since the pathological condition related to RBC, primarily originates from a single cell infection, therefore, it is important to relate the deformation dynamics to the mechanical properties (such as, bending rigidity and membrane elasticity). In the present study, numerical simulation of a healthy and malaria infected RBC in a constricted channel is analyzed. The flow simulations are carried out using finite sized dissipative particle dynamics (FDPD) method in conjunction with a discrete model that represents the membrane of the RBC. The numerical equivalent of optical tweezers test is validated against the experimental studies. Two different types of constrictions, viz., a converging-diverging type tapered channel and a stenosed microchannel are considered for the simulation. The effect of degree of constriction and the flow rate effect on the RBC is investigated. It was observed that, as the flow rate decreases, the infected RBC completely blocks the micro vessel. The transit time for infected cell drastically increases compared to healthy RBC. Our simulations indicate that, there is a critical flow rate below which infected RBC cannot pass through the micro capillary.

Novel silicon microchannels device for use in red blood cell deformability studies

NASA Astrophysics Data System (ADS)

Zheng, Xiao-Lin; Liao, Yan-Jian; Zhang, Wen-Xian

2001-10-01

Currently, a number of techniques are used to access cell deformability. We study a novel silicon microchannels device for use in red blood cell deformability. The channels are produced in silicon substrate using microengineering technology. The microgrooves formed in the surface of a single-crystal silicon substrate. They were converted to channels by tightly covering them with an optical flat glass plate. An array of flow channels (number 950 in parallel) have typical dimensions of 5 micrometers width X 5.5 Xm depth, and 30 micrometers length. There the RBC's are forced to pass through channels. Thus, the microchannels are used to simulate human blood capillaries. It provides a specific measurement of individual cell in terms of both flow velocity profile and an index of cell volume while the cell flow through the channels. It dominates the complex cellular flow behavior, such as, the viscosity of whole blood is a nonlinear function of shear rate, index of filtration, etc.

An experimental study of the elastic theory for granular flows

NASA Astrophysics Data System (ADS)

Guo, Tongtong; Campbell, Charles S.

2016-08-01

This paper reports annular shear cell measurements granular flows with an eye towards experimentally confirming the flow regimes laid out in the elastic theory of granular flow. Tests were carried out on four different kinds of plastic spherical particles under both constant volume flows and constant applied stress flows. In particular, observations were made of the new regime in that model, the elastic-inertial regime, and the predicted transitions between the elastic-inertial and both the elastic-quasistatic and pure inertial regimes.

Quantitative Analysis of Cell Migration Using Optical Flow

PubMed Central

Boric, Katica; Orio, Patricio; Viéville, Thierry; Whitlock, Kathleen

2013-01-01

Neural crest cells exhibit dramatic migration behaviors as they populate their distant targets. Using a line of zebrafish expressing green fluorescent protein (sox10:EGFP) in neural crest cells we developed an assay to analyze and quantify cell migration as a population, and use it here to characterize in detail the subtle defects in cell migration caused by ethanol exposure during early development. The challenge was to quantify changes in the in vivo migration of all Sox10:EGFP expressing cells in the visual field of time-lapse movies. To perform this analysis we used an Optical Flow algorithm for motion detection and combined the analysis with a fit to an affine transformation. Through this analysis we detected and quantified significant differences in the cell migrations of Sox10:EGFP positive cranial neural crest populations in ethanol treated versus untreated embryos. Specifically, treatment affected migration by increasing the left-right asymmetry of the migrating cells and by altering the direction of cell movements. Thus, by applying this novel computational analysis, we were able to quantify the movements of populations of cells, allowing us to detect subtle changes in cell behaviors. Because cranial neural crest cells contribute to the formation of the frontal mass these subtle differences may underlie commonly observed facial asymmetries in normal human populations. PMID:23936049

Performance of a vanadium redox flow battery with tubular cell design

NASA Astrophysics Data System (ADS)

Ressel, Simon; Laube, Armin; Fischer, Simon; Chica, Antonio; Flower, Thomas; Struckmann, Thorsten

2017-07-01

We present a vanadium redox flow battery with a tubular cell design which shall lead to a reduction of cell manufacturing costs and the realization of cell stacks with reduced shunt current losses. Charge/discharge cycling and polarization curve measurements are performed to characterize the single test cell performance. A maximum current density of 70 mAcm-2 and power density of 142 Wl-1 (per cell volume) is achieved and Ohmic overpotential is identified as the dominant portion of the total cell overpotential. Cycling displays Coulomb efficiencies of ≈95% and energy efficiencies of ≈55%. During 113 h of operation a stable Ohmic cell resistance is observed.

Effects of resource supplements on mature ciliate biofilms: an empirical test using a new type of flow cell.

PubMed

Norf, Helge; Arndt, Hartmut; Weitere, Markus

2009-11-01

Biofilm-dwelling consumer communities play an important role in the matter flux of many aquatic ecosystems. Due to their poor accessibility, little is as yet known about the regulation of natural biofilms. Here, a new type of flow cell is presented which facilitates both experimental manipulation and live observation of natural, pre-grown biofilms. These flow cells were used to study the dynamics of mature ciliate biofilms in response to supplementation of planktonic bacteria. The results suggest that enhanced ciliate productivity could be quickly transferred to micrometazoans (ciliate grazers), making the effects on the standing stock of the ciliates detectable only for a short time. Likewise, no effect on ciliates appeared when micrometazoan consumers were ab initio abundant. This indicates the importance of 'top-down' control of natural ciliate biofilms. The flow cells used here offer great potential for experimentally testing such control mechanisms within naturally cultivated biofilms.

Improved Diffuse Fluorescence Flow Cytometer Prototype for High Sensitivity Detection of Rare Circulating Cells In Vivo

NASA Astrophysics Data System (ADS)

Pestana, Noah Benjamin

Accurate quantification of circulating cell populations is important in many areas of pre-clinical and clinical biomedical research, for example, in the study of cancer metastasis or the immune response following tissue and organ transplants. Normally this is done "ex-vivo" by drawing and purifying a small volume of blood and then analyzing it with flow cytometry, hemocytometry or microfludic devices, but the sensitivity of these techniques are poor and the process of handling samples has been shown to affect cell viability and behavior. More recently "in vivo flow cytometry" (IVFC) techniques have been developed where fluorescently-labeled cells flowing in a small blood vessel in the ear or retina are analyzed, but the sensitivity is generally poor due to the small sampling volume. To address this, our group recently developed a method known as "Diffuse Fluorescence Flow Cytometry" (DFFC) that allows detection and counting of rare circulating cells with diffuse photons, offering extremely high single cell counting sensitivity. In this thesis, an improved DFFC prototype was designed and validated. The chief improvements were three-fold, i) improved optical collection efficiency, ii) improved detection electronics, and iii) development of a method to mitigate motion artifacts during in vivo measurements. In combination, these improvements yielded an overall instrument detection sensitivity better than 1 cell/mL in vivo, which is the most sensitive IVFC system reported to date. Second, development and validation of a low-cost microfluidic device reader for analysis of ocular fluids is described. We demonstrate that this device has equivalent or better sensitivity and accuracy compared a fluorescence microscope, but at an order-of-magnitude reduced cost with simplified operation. Future improvements to both instruments are also discussed.

Flow cytometric single cell analysis reveals heterogeneity between adipose depots

PubMed Central

Boumelhem, Badwi B.; Assinder, Stephen J.; Bell-Anderson, Kim S.; Fraser, Stuart T.

2017-01-01

ABSTRACT Understanding adipose tissue heterogeneity is hindered by the paucity of methods to analyze mature adipocytes at the single cell level. Here, we report a system for analyzing live adipocytes from different adipose depots in the adult mouse. Single cell suspensions of buoyant adipocytes were separated from the stromal vascular fraction and analyzed by flow cytometry. Compared to other lipophilic dyes, Nile Red uptake effectively distinguished adipocyte populations. Nile Red fluorescence increased with adipocyte size and granularity and could be combined with MitoTracker® Deep Red or fluorescent antibody labeling to further dissect adipose populations. Epicardial adipocytes exhibited the least mitochondrial membrane depolarization and highest fatty-acid translocase CD36 surface expression. In contrast, brown adipocytes showed low surface CD36 expression. Pregnancy resulted in reduced mitochondrial membrane depolarisation and increased CD36 surface expression in brown and epicardial adipocyte populations respectively. Our protocol revealed unreported heterogeneity between adipose depots and highlights the utility of flow cytometry for screening adipocytes at the single cell level. PMID:28453382

Routine detection of Epstein-Barr virus specific T-cells in the peripheral blood by flow cytometry

NASA Technical Reports Server (NTRS)

Crucian, B. E.; Stowe, R. P.; Pierson, D. L.; Sams, C. F.

2001-01-01

The ability to detect cytomegalovirus-specific T-cells (CD4(+)) in the peripheral blood by flow cytometry has been recently described by Picker et al. In this method, cells are incubated with viral antigen and responding (cytokine producing) T-cells are then identified by flow cytometry. To date, this technique has not been reliably used to detect Epstein-Barr virus (EBV)-specific T-cells primarily due to the superantigen/mitogenic properties of the virus which non-specifically activate T-cells. By modifying culture conditions under which the antigens are presented, we have overcome this limitation and developed an assay to detect and quantitate EBV-specific T-cells. The detection of cytokine producing T-cells by flow cytometry requires an extremely strong signal (such as culture in the presence of PMA and ionomycin). Our data indicate that in modified culture conditions (early removal of viral antigen) the non-specific activation of T-cells by EBV is reduced, but antigen presentation will continue uninhibited. Using this method, EBV-specific T-cells may be legitimately detected using flow cytometry. No reduction in the numbers of antigen-specific T-cells was observed by the early removal of target antigen when verified using cytomegalovirus antigen (a virus with no non-specific T-cell activation properties). In EBV-seropositive individuals, the phenotype of the EBV-specific cytokine producing T-cells was evaluated using four-color flow cytometry and found to be CD45(+), CD3(+), CD4(+), CD45RA(-), CD69(+), CD25(-). This phenotype indicates the stimulation of circulating previously unactivated memory T-cells. No cytokine production was observed in CD4(+) T-cells from EBV-seronegative individuals, confirming the specificity of this assay. In addition, the use of four color cytometry (CD45, CD3, CD69, IFNgamma/IL-2) allows the total quantitative assessment of EBV-specific T-cells while monitoring the interference of EBV non-specific mitogenic activity. This method may

Non-Flow-Through Fuel Cell System Test Results and Demonstration on the SCARAB Rover

NASA Technical Reports Server (NTRS)

Scheidegger, Brianne, T.; Burke, Kenneth A.; Jakupca, Ian J.

2012-01-01

This paper describes the results of the demonstration of a non-flow-through PEM fuel cell as part of a power system on the SCARAB rover. A 16-cell non-flow-through fuel cell stack from Infinity Fuel Cell and Hydrogen, Inc. was incorporated into a power system designed to act as a range extender by providing power to the rover s hotel loads. This work represents the first attempt at a ground demonstration of this new technology aboard a mobile test platform. Development and demonstration were supported by the Office of the Chief Technologist s Space Power Systems Project and the Advanced Exploration System Modular Power Systems Project.

Binding of fluoresceinated epidermal growth factor to A431 cell sub-populations studied using a model-independent analysis of flow cytometric fluorescence data.

PubMed Central

Chatelier, R C; Ashcroft, R G; Lloyd, C J; Nice, E C; Whitehead, R H; Sawyer, W H; Burgess, A W

1986-01-01

A method is developed for determining ligand-cell association parameters from a model-free analysis of data obtained with a flow cytometer. The method requires measurement of the average fluorescence per cell as a function of ligand and cell concentration. The analysis is applied to data obtained for the binding of fluoresceinated epidermal growth factor to a human epidermoid carcinoma cell line, A431. The results indicate that the growth factor binds to two classes of sites on A431 cells: 4 X 10(4) sites with a dissociation constant (KD) of less than or equal to 20 pM, and 1.5 X 10(6) sites with a KD of 3.7 nM. A derived plot of the average fluorescence per cell versus the average number of bound ligands per cell is used to construct binding isotherms for four sub-populations of A431 cells fractionated on the basis of low-angle light scatter. The four sub-populations bind the ligand with equal affinity but differ substantially in terms of the number of binding sites per cell. We also use this new analysis to critically evaluate the use of 'Fluorotrol' as a calibration standard in flow cytometry. PMID:3015587

Vortex-dislodged cells from bone marrow trephine biopsy yield satisfactory results for flow cytometric immunophenotyping.

PubMed

Bommannan, K; Sachdeva, M U S; Gupta, M; Bose, P; Kumar, N; Sharma, P; Naseem, S; Ahluwalia, J; Das, R; Varma, N

2016-10-01

A good bone marrow (BM) sample is essential in evaluating many hematologic disorders. An unsuccessful BM aspiration (BMA) procedure precludes a successful flow cytometric immunophenotyping (FCI) in most hematologic malignancies. Apart from FCI, most ancillary diagnostic techniques in hematology are less informative. We describe the feasibility of FCI in vortex-dislodged cell preparation obtained from unfixed trephine biopsy (TB) specimens. In pancytopenic patients and dry tap cases, routine diagnostic BMA and TB samples were complemented by additional trephine biopsies. These supplementary cores were immediately transferred into sterile tubes filled with phosphate-buffered saline, vortexed, and centrifuged. The cell pellet obtained was used for flow cytometric immunophenotyping. Of 7955 BMAs performed in 42 months, 34 dry tap cases were eligible for the study. Vortexing rendered a cell pellet in 94% of the cases (32 of 34), and FCI rendered a rapid diagnosis in 100% of the cases (32 of 32) where cell pellets were available. We describe an efficient procedure which could be effectively utilized in resource-limited centers and reduce the frequency of repeat BMA procedures. © 2016 John Wiley & Sons Ltd.

Microfluidic flow cytometer for quantifying photobleaching of fluorescent proteins in cells

PubMed Central

Lubbeck, Jennifer L.; Dean, Kevin M.; Ma, Hairong; Palmer, Amy E.; Jimenez, Ralph

2012-01-01

Traditional flow cytometers are capable of rapid cellular assays on the basis of fluorescence intensity and light scatter. Microfluidic flow cytometers have largely followed the same path of technological development as their traditional counterparts, however the significantly smaller transport distance and resulting lower cell speeds in microchannels provides for the opportunity to detect novel spectroscopic signatures based on multiple, non-temporally-coincident excitation beams. Here, we characterize the design and operation of a cytometer with a 3-beam, probe/bleach/probe geometry, employing HeLa suspension cells expressing fluorescent proteins. The data collection rate exceeds 20 cells/s under a range of beam intensities (5 kW – 179 kW/cm2). The measured percent photobleaching (ratio of fluorescence intensities excited by the first and third beams: Sbeam3/Sbeam1) partially resolves a mixture of four red fluorescent proteins in mixed samples. Photokinetic simulations are presented and demonstrate that the percent photobleaching reflects a combination of the reversible and irreversible photobleaching kinetics. By introducing a photobleaching optical signature, which complements traditional fluorescence intensity-based detection, this method adds another dimension to multi-channel fluorescence cytometry, and provides a means for flow-cytometry-based screening of directed libraries of fluorescent protein photobleaching. PMID:22424298

Numerical analysis of cell adhesion in capillary flow

NASA Astrophysics Data System (ADS)

Takeishi, Naoki; Imai, Yohsuke; Ishida, Shunichi; Omori, Toshihiro; Kamm, Roger; Ishikawa, Takuji

2016-11-01

Numerical simulation of cell adhesion was performed for capillaries whose diameter is comparable to or smaller than that of the cell. Despite a lot of works about leukocyte and tumor cell rolling, cell motion in capillaries has remained unclear. The solid and fluid mechanics of a cell in flow was coupled with a slip bond model of ligand-receptor interactions. When the size of a capillary was reduced, the cell always transitioned to "bullet-like" motion, with a consequent decrease in the velocity of the cell. A state diagram is obtained for various values of capillary diameter and receptor density. According to our numerical results, bullet motion enables firm adhesion of a cell to the capillary wall even for a weak ligand-receptor binding. We also quantified effects of various parameters, including the dissociation rate constant, the spring constant, and the reactive compliance on the characteristics of cell motion. Our results suggest that even under the interaction between PSGL-1 and P-selectin, which is mainly responsible for leukocyte rolling, a cell is able to show firm adhesion in a small capillary. These findings may help in understanding such phenomena as leukocyte plugging and cancer metastasis. This research was supported by JSPS KAKENHI Grant Numbers 25000008, 26107703, 14J03967. We also acknowledge support from the Tohoku University Division for International Advanced Research and Education Organization.

Comparative exploration of multidimensional flow cytometry software: a model approach evaluating T cell polyfunctional behavior.

PubMed

Spear, Timothy T; Nishimura, Michael I; Simms, Patricia E

2017-08-01

Advancement in flow cytometry reagents and instrumentation has allowed for simultaneous analysis of large numbers of lineage/functional immune cell markers. Highly complex datasets generated by polychromatic flow cytometry require proper analytical software to answer investigators' questions. A problem among many investigators and flow cytometry Shared Resource Laboratories (SRLs), including our own, is a lack of access to a flow cytometry-knowledgeable bioinformatics team, making it difficult to learn and choose appropriate analysis tool(s). Here, we comparatively assess various multidimensional flow cytometry software packages for their ability to answer a specific biologic question and provide graphical representation output suitable for publication, as well as their ease of use and cost. We assessed polyfunctional potential of TCR-transduced T cells, serving as a model evaluation, using multidimensional flow cytometry to analyze 6 intracellular cytokines and degranulation on a per-cell basis. Analysis of 7 parameters resulted in 128 possible combinations of positivity/negativity, far too complex for basic flow cytometry software to analyze fully. Various software packages were used, analysis methods used in each described, and representative output displayed. Of the tools investigated, automated classification of cellular expression by nonlinear stochastic embedding (ACCENSE) and coupled analysis in Pestle/simplified presentation of incredibly complex evaluations (SPICE) provided the most user-friendly manipulations and readable output, evaluating effects of altered antigen-specific stimulation on T cell polyfunctionality. This detailed approach may serve as a model for other investigators/SRLs in selecting the most appropriate software to analyze complex flow cytometry datasets. Further development and awareness of available tools will help guide proper data analysis to answer difficult biologic questions arising from incredibly complex datasets. © Society

Preliminary study of high energy density Zn/Ni flow batteries

NASA Astrophysics Data System (ADS)

Liu, Jin; Wang, Yan

2015-10-01

The escalation of power system promotes the development of energy storage technologies (ESTs). Among all of ESTs, battery technologies develop quickly and diversely because of its huge application market. Aqueous redox flow batteries (RFBs) are very attractive to customers in the energy grid system, and their noticeable technological innovations in past decades are driving them to gradually replace the conventional ESTs under certain circumstance. Here, the first fully-flow-able zinc-nickel flow battery (ZNFB) is preliminary reported in this paper, and its superior performance is supposed to be suitable for both large-scale storage need and carry-on powertrain in cars. Through using semi-solid fuel cell (SSFC) technology, we incorporates the beneficial features of Zn/Ni chemistry (essentially sustainable, eco-friendly and deposit-abundant) into RFB structure to make a ;hybrid; flow battery system, which can take the advantage of both. The relationship between carbon loading and suspension conductivity is determined. Electrochemical properties of ZNFB as static test, cycling test, and fully flowing test are studied to demonstrate our design.

Surfactant functionalization induces robust, differential adhesion of tumor cells and blood cells to charged nanotube-coated biomaterials under flow.

PubMed

Mitchell, Michael J; Castellanos, Carlos A; King, Michael R

2015-07-01

The metastatic spread of cancer cells from the primary tumor to distant sites leads to a poor prognosis in cancers originating from multiple organs. Increasing evidence has linked selectin-based adhesion between circulating tumor cells (CTCs) and endothelial cells of the microvasculature to metastatic dissemination, in a manner similar to leukocyte adhesion during inflammation. Functionalized biomaterial surfaces hold promise as a diagnostic tool to separate CTCs and potentially treat metastasis, utilizing antibody and selectin-mediated interactions for cell capture under flow. However, capture at high purity levels is challenged by the fact that CTCs and leukocytes both possess selectin ligands. Here, a straightforward technique to functionalize and alter the charge of naturally occurring halloysite nanotubes using surfactants is reported to induce robust, differential adhesion of tumor cells and blood cells to nanotube-coated surfaces under flow. Negatively charged sodium dodecanoate-functionalized nanotubes simultaneously enhanced tumor cell capture while negating leukocyte adhesion, both in the presence and absence of adhesion proteins, and can be utilized to isolate circulating tumor cells regardless of biomarker expression. Conversely, diminishing nanotube charge via functionalization with decyltrimethylammonium bromide both abolished tumor cell capture while promoting leukocyte adhesion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Surfactant Functionalization Induces Robust, Differential Adhesion of Tumor Cells and Blood Cells to Charged Nanotube-Coated Biomaterials Under Flow

PubMed Central

Mitchell, Michael J.; Castellanos, Carlos A.; King, Michael R.

2015-01-01

The metastatic spread of cancer cells from the primary tumor to distant sites leads to a poor prognosis in cancers originating from multiple organs. Increasing evidence has linked selectin-based adhesion between circulating tumor cells (CTCs) and endothelial cells of the microvasculature to metastatic dissemination, in a manner similar to leukocyte adhesion during inflammation. Functionalized biomaterial surfaces hold promise as a diagnostic tool to separate CTCs and potentially treat metastasis, utilizing antibody and selectin-mediated interactions for cell capture under flow. However, capture at high purity levels is challenged by the fact that CTCs and leukocytes both possess selectin ligands. Here, a straightforward technique to functionalize and alter the charge of naturally occurring halloysite nanotubes using surfactants is reported to induce robust, differential adhesion of tumor cells and blood cells to nanotube-coated surfaces under flow. Negatively charged sodium dodecanoate-functionalized nanotubes simultaneously enhanced tumor cell capture while negating leukocyte adhesion, both in the presence and absence of adhesion proteins, and can be utilized to isolate circulating tumor cells regardless of biomarker expression. Conversely, diminishing nanotube charge via functionalization with decyltrimethylammonium bromide both abolished tumor cell capture while promoting leukocyte adhesion. PMID:25934290

A flow cytometric approach to the study of crustacean cellular immunity

USGS Publications Warehouse

Cardenas, W.; Jenkins, J.A.; Dankert, J.R.

2000-01-01

Responses of hemocytes from the crayfish Procambarus zonangulus to stimulation by fungal cell walls (Zymosan A) were measured by flow cytometry. Changes in hemocyte physical characteristics were assessed flow cytometrically using forward- and sidescatter light parameters, and viability was measured by two-color fluorescent staining with calcein-AM and ethidium homodimer 1. The main effects of zymosan A on crayfish hemocytes were reduction in cell size and viability compared to control mixtures (hemocytes in buffer only). Adding diethyldithiocarbamic acid, an inhibitor of phenoloxidase, to hemocyte to zymosan mixtures delayed the time course of cell size reduction and cell death compared to zymosan-positive controls. The inclusion of trypsin inhibitor in reaction mixtures further delayed the reduction in hemocyte size and cell death, thereby indicating that a proteolytic cascade, along with prophenoloxidase activation, played a key role in generating signal molecules which mediate these cellular responses. In addition to traditional methods such as microscopy and protein chemistry, flow cytometry can provide a simple, reproducible, and sensitve method for evaluating invertebrate hemocyte responses to immunological stimuli.

An imaging flow cytometry method to assess ricin trafficking in A549 human lung epithelial cells.

PubMed

Jenner, Dominic; Chong, Damien; Walker, Nicola; Green, A Christopher

2018-02-01

The endocytosis and trafficking of ricin in mammalian cells is an important area of research for those producing ricin anti-toxins and other ricin therapeutics. Ricin trafficking is usually observed by fluorescence microscopy techniques. This gives good resolution and leads to a detailed understanding of the internal movement of ricin within cells. However, microscopy techniques are often hampered by complex analysis and quantification techniques, and the inability to look at ricin trafficking in large populations of cells. In these studies we have directly labelled ricin and assessed if its trafficking can be observed using Imaging Flow Cytometry (IFC) both to the cytoplasmic region of cells and specifically to the Golgi apparatus. Using IDEAS® data analysis software the specific fluorescence location of the ricin within the cells was analysed. Then, using cytoplasmic masking techniques to quantify the number of cells with endocytosed cytoplasmic ricin or cells with Golgi-associated ricin, kinetic endocytosis curves were generated. Here we present, to the authors' knowledge, the first example of using imaging flow cytometry for evaluating the subcellular transport of protein cargo, using the trafficking of ricin toxin in lung cells as a model. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Opto-fluidics based microscopy and flow cytometry on a cell phone for blood analysis.

PubMed

Zhu, Hongying; Ozcan, Aydogan

2015-01-01

Blood analysis is one of the most important clinical tests for medical diagnosis. Flow cytometry and optical microscopy are widely used techniques to perform blood analysis and therefore cost-effective translation of these technologies to resource limited settings is critical for various global health as well as telemedicine applications. In this chapter, we review our recent progress on the integration of imaging flow cytometry and fluorescent microscopy on a cell phone using compact, light-weight and cost-effective opto-fluidic attachments integrated onto the camera module of a smartphone. In our cell-phone based opto-fluidic imaging cytometry design, fluorescently labeled cells are delivered into the imaging area using a disposable micro-fluidic chip that is positioned above the existing camera unit of the cell phone. Battery powered light-emitting diodes (LEDs) are butt-coupled to the sides of this micro-fluidic chip without any lenses, which effectively acts as a multimode slab waveguide, where the excitation light is guided to excite the fluorescent targets within the micro-fluidic chip. Since the excitation light propagates perpendicular to the detection path, an inexpensive plastic absorption filter is able to reject most of the scattered light and create a decent dark-field background for fluorescent imaging. With this excitation geometry, the cell-phone camera can record fluorescent movies of the particles/cells as they are flowing through the microchannel. The digital frames of these fluorescent movies are then rapidly processed to quantify the count and the density of the labeled particles/cells within the solution under test. With a similar opto-fluidic design, we have recently demonstrated imaging and automated counting of stationary blood cells (e.g., labeled white blood cells or unlabeled red blood cells) loaded within a disposable cell counting chamber. We tested the performance of this cell-phone based imaging cytometry and blood analysis platform

Studying leukemia metastasis and therapy monitoring by in vivo imaging and flow cytometer