Uniform lateral orientation, caused by flow forces, of flat particles in flow-through systems.

Kachel, Volker; Kordwig, E; Glossner, E

doi:10.1177/25.7.330727

Cited by 34 publications

(11 citation statements)

References 4 publications

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“…Of particular importance are the velocity gradients. If there is a positive longitudinal gradient, that is, the particle is moving into a higher velocity region, a n elongated object will achieve a stable orientation with its long axis parallel to the direction of flow (7,8). It also experiences a stretching force, and will be deformed if it is elastic (13).…”

Section: Discussionmentioning

confidence: 99%

Orientation measurements of microsphere doublets and metaphase chromosomes in flow

Lucas¹,

Pinkel²

1986

Cytometry

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Obtaining information about the shape of particles from slit‐scan profiles is facilitated if the particles are oriented. Elongated particles orient in the nozzle of flow cytometers, but orientation may be disrupted before the particles get to the point of measurement. We have used our slit‐scan flow cytometer to investigate the orientation of microsphere doublets in a liquid jet in air, in flow across a glass surface, and in a 200‐μm‐square capillary tube as a function of distance from the flow chamber nozzle. Particles were classified as being oriented if there was a centrally located dip in the slit‐scan profile. Essentially all the doublets in the jet were oriented, and no disorientation was noted over the distances measured (up to 10 mm from the nozzle). Particle orientation was maintained for 80 μm in flow across a glass surface. In the capillary‐type flow chamber, essentially all of the particles were oriented at the tube entrance and for several millimeters into the tube. There then occurred a region where particle tumbling started and progressively fewer doublets met the orientation criteria. The distance to where tumbling began could be estimated by calculating the length required to establish the parabolic flow profile in the tube. Finally, the fraction of oriented particles reached a constant value that did not change with increased distance into the tube. When sample was injected off axis (i.e., half‐way between the chamber center and the chamber walls), particle tumbling began closer to the tube entrance.Orientation studies of Chinese hamster M3–1 metaphase chromosomes showed that over 95% of the larger chromosomes (1–5) and over 65% of the smaller chromosomes (9–11) were oriented near the entrance of the capillary tube.

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Section: Discussionmentioning

confidence: 99%

Orientation measurements of microsphere doublets and metaphase chromosomes in flow

Lucas¹,

Pinkel²

1986

Cytometry

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“…The second stage of orientation is provided by a rectangular flow orifice of approximately 75 pm X 250 pm (5). Orifices with higher aspect ratios, ranging up to 1:10 (50 pm x 500 pm) were explored but did not improve performance.…”

Section: Et Almentioning

confidence: 99%

High resolution DNA content measurements of mammalian sperm

et al. 1982

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The high condensation and flat shape of the mammalian sperm nucleus present unique difficulties to flow cytometric measurement of DNA content. Chromatin compactness makes quantitative fluorescent staining for DNA difficult and causes a high index of refraction. The refractive index makes optical measurements sensitive to sperm head orientation. We demonstrate that the optical problems can be overcome using the commercial ICP22 epiillumination flow cytometer (Ortho Instruments, Westwood, MA) or a specially built cell orientating flow cytometer (OFCM). The design and operation of the OFCM are described. Measurements of the angular dependence of fluorescence from acriflavine stained rabbit sperm show that it is capable of orienting flat sperm with a tolerance of +7 degrees.Differences in the angular dependence for the similarly shaped bull and rabbit sperm allow discrimination of these cells. We show that DNA staining with 4-6 diamidino-2-phenylindole (DAF'I) or an ethidium bromide mithramycin combination allows resolution of the X and Y populations in mouse sperm.They have also been successful with sperm from the bull, ram, rabbit, and boar. Reliable results with human sperm are not obtained. The accuracy of the staining and measurement techniques are verified by the correct determination of the relative DNA content of these two populations in sperm from normal mice and those with the Cattanach [7 to XI translocation. Among the potential uses of these techniques are measurement of DNA content errors induced in sperm due to mutagen exposure, and assessment of the fractions of X and Y sperm in semen that may have one population artifically enriched.

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“…Therefore, it is important to evaluate the stability of the liquid path when particles flow through the illumination area inside the flow chamber (1)(2)(3)(4)(5)(6)(7)(8). Single cells or microspheres in suspension flow linearly through a flow chamber at a high speed and are illuminated by a shaped laser beam.…”

mentioning

confidence: 99%

“…Hence, it affects the intensity and width of the scattering and fluorescence signals. Therefore, it is important to evaluate the stability of the liquid path when particles flow through the illumination area inside the flow chamber (1)(2)(3)(4)(5)(6)(7)(8).…”

mentioning

confidence: 99%

Evaluating the liquid path stability of a flow cytometer

et al. 2016

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Precision in flow cytometry depends on many factors, the first of which is accurate and stable positioning of the hydrodynamically focused cells. However, no method exists to evaluate the stability of laminar flow and single-cell flow in the flow chamber of the flow cytometer directly because of the small size of the rectangular channel of the flow chamber. In this paper, a method of high-speed particle image velocimetry is proposed to solve this problem. The velocity stability of the particles in the flow chamber is used to evaluate the flow stability of the fluid path of the flow cytometer. The side scattering images of particles are obtained by a high-speed camera. Upon exposure, cells were imaged at random positions in the flow cell, resulting in four different types of the images: blank, inadequate, normal, or overlapped. Normal images were identified utilizing a grey cluster analysis algorithm based on trapezoid whitenization weight functions. A mid-point method is applied to determine the length of the particle track at a fixed exposure time. The variation of the trajectory lengths of the normal images are used to evaluate the stability of the liquid path. Experiments are carried out to verify the feasibility of our method in which different diameter microspheres at different flow rates. The results indicate that the standard deviation and relative standard deviation of the trajectory lengths can be used as the evaluation indices of the liquid path stability of the flow cytometer. © 2016 International Society for Advancement of Cytometry.

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Uniform lateral orientation, caused by flow forces, of flat particles in flow-through systems.

Cited by 34 publications

References 4 publications

Orientation measurements of microsphere doublets and metaphase chromosomes in flow

Orientation measurements of microsphere doublets and metaphase chromosomes in flow

High resolution DNA content measurements of mammalian sperm

Evaluating the liquid path stability of a flow cytometer

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