Spiral swimming of an artificial micro-swimmer

A device constructed from a filament of paramagnetic beads connected to a human red blood cell will swim when subject to an oscillating magnetic field. Bending waves propagate from the tip of the tail toward the red blood cell in a fashion analogous to flagellum beating, making the artificial swimmer a candidate for studying what has been referred to as ‘flexible oar’ micro-swimming. In this study, we demonstrate that under the influence of a rotating field the artificial swimmer will perform ‘corkscrew’-type swimming. We conduct numerical simulations of the swimmer where the paramagnetic tail is represented as a series of rigid spheres connected by flexible but inextensible links. An optimal range of parameters governing the relative strength of viscous, elastic and magnetic forces is identified for swimming speed. A parameterization of the motion is extracted and examined as a function of the driving frequency. With a continuous elastica/resistive force model, we obtain an expression for the swimming speed in the low-frequency limit. Using this expression we explore further the effects of the applied field, the ratio of the transverse field to the constant field, and the ratio of the radius of the sphere to the length of the filament tail on the resulting dynamics.

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Sensitivity to change in electrical environment: a new bioelectric effect

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1980.239.5.r424 ◽

1980 ◽

Vol 239 (5) ◽

pp. R424-R427 ◽

Cited By ~ 1

Author(s):

A. A. Marino ◽

J. M. Cullen ◽

M. Reichmanis ◽

R. O. Becker ◽

F. X. Hart

Keyword(s):

Electric Field ◽

Blood Cell ◽

Electric Fields ◽

Red Blood Cell ◽

Low Frequency ◽

Sensitivity To Change ◽

Bioelectric Effect ◽

Cell Concentrations ◽

Inappropriate Choice

The action of a 60-Hz, 5 kV/m electric field on erythrocyte parameters in mice was determined. No effects attributable to the magnitude of the field were found, but a transition either from or to an environment containing the field caused decreased red blood cell concentrations and decreased hematocrits. The failure of others to observe effects on erythrocyte parameters following exposure to low-frequency electric fields may have been due to an inappropriate choice of duration of exposure.

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Prevalence of erythrocyte alloimmunization in polytransfused patients

Einstein (São Paulo) ◽

10.1590/s1679-45082011ao1777 ◽

2011 ◽

Vol 9 (2) ◽

pp. 173-178 ◽

Cited By ~ 2

Author(s):

Roberto de Oliveira Cruz ◽

Mariza Aparecida Mota ◽

Fabiana Mendes Conti ◽

Ricardo Antônio d'Almeida Pereira ◽

Jose Mauro Kutner ◽

...

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

Blood Cells ◽

High Probability ◽

Low Frequency ◽

Albert Einstein ◽

Red Cell ◽

Hemolytic Disease ◽

High Incidence ◽

Transfusion Reactions

Objective: To determine the incidence and the rate of red blood cell alloimmunization in polytransfused patients. Methods: A polytransfused patient was defined as having received at least 6 units of red cell concentrates during a 3-month period. The records of all patients (n = 12,904) who had received red blood cell units were examined retrospectively by searching the computer database at Hospital Israelita Albert Einstein in São Paulo, Brazil, over a 6-year period, between 2003 and 2009. Results: During this time, 77,049 red cell concentrate transfusions were performed in 12,904 patients. There were 3,044 polytransfused patients, 227 of whom (7.5%) presented with irregular erythrocyte antibodies. The prevalence of alloantibody specificity was: Anti-E>anti-D>anti-K>anti-C>anti-Dia>anti-c>anti-Jka>anti-S in 227 polytransfused patients. We found combinations of alloantibodies in 79 patients (34.8%), and the most common specificities were against the Rh and/or Kell systems. These antibodies show clinical significance, as they can cause delayed hemolytic transfusion reactions and perinatal hemolytic disease. About 20% of the patients showed an IgG autoantibody isolated or combined with alloantibodies. Interestingly, a high incidence of antibodies against low frequency antigens was detected in this study, mainly anti-Dia. Conclusion: Polytransfused patients have a high probability of developing alloantibodies whether alone or combined with autoantibodies and antibodies against low frequency antigens. Transfusion of red blood cells with a phenotype-compatible with RH (C, E, c), K, Fya, and Jka antigens is recommended for polytransfused patients in order to prevent alloimmunization and hemolytic transfusion reactions.

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High frequency photoacoustic detection of red blood cell aggregation

10.32920/ryerson.14648790 ◽

2021 ◽

Author(s):

Fayruz Kibria

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

High Frequency ◽

Photoacoustic Imaging ◽

Low Frequency ◽

Cell Aggregation ◽

Center Frequency ◽

Photoacoustic Detection ◽

Rbc Aggregation

Red blood cell (RBC) aggregation was correctly reported in early 1768 as the increased deposition for blood to form spots of red in pathological conditions. However only recently have there been advances in technology to allow possible detection of RBC aggregation in vivo. Photoacoustic imaging (PA) shows a promising future in the detection of simultaneous in vivo RBC aggregation and oxygen saturation. This work presents, for the first time, the results of investigating aggregated RBCs using high frequency (> 20 MHz) photoacoustic (PA) imaging. Aggregation was induced by using 3% w/v concentration of 70 kDa Dextran and PA measurements were taken by a 25 MHz center frequency transducer. It was found that the spectral slope (SS) of the photoacoustic signals decreased by ~0.25 dB/MHz with RBC aggregation. The results are consistent with the findings of low frequency PA RBC aggregation study which also reported decrease in SS with increased aggregation.

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