The Electrical Conductance of Suspensions of Ellipsoids and Its Relation to the Study of Avian Erythrocytes

Velick, Sidney; Gorin, Manuel H.

doi:10.1085/jgp.23.6.753

Cited by 91 publications

(24 citation statements)

References 5 publications

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“…Under usual conditions the field strength at a certain distance from the orifice can be neglected against the field strength in the orifice. From the calculations of Maxwell [22], Fricke [23] and Velick and Gorin [24] used also by Grover et al [25], it can be derived, how the particle pulse height, A U, depends on: a) the volume, A V, the shape and resistivity of the measured b) the cross section of the orifice, q, c) the resistivity of the suspending electrolyte, p z , d) the electric current, i, through the orifice if the electric field particles expressed by the factor, A around the particle can be considered homogeneous:…”

Section: The Electric Field In the Orifice Its Distribution And Its mentioning

confidence: 99%

Investigations into Coulter Sizing of Biological Particles; Theoretical Background and Instrumental Improvements

Kachel

1986

Part & Part Syst Charact

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The electric resistance pulse or electric sensing zone method, primarily invented by W. H. Coulter, is well suited for volume measurements of biological cells and other particles. This review summarizes the methodological investigations at the Max-Planck-Institut fur Biochemie into the Coulter method, particularly for measuring biological cells. The distribution of the electric field in Coulter orifices was measured in enlarged model orifices and, additionally, calculated by computer programs. It is shown that the local resistance pulse height depends on the square of the local electrical fieldstrength and that the particle path in the orifice influences the measured pulse heights and the orientation and deformation of particles. A new transducer system is explained which uses hydrodynamic focusing and allows short time kinetic measurements. It is equipped with a calibrator system which serves also as general control unit.

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Section: The Electric Field In the Orifice Its Distribution And Its mentioning

confidence: 99%

Investigations into Coulter Sizing of Biological Particles; Theoretical Background and Instrumental Improvements

Kachel

1986

Part & Part Syst Charact

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“…Among all the techniques developed to measure soil water content (h), electromagnetic methods to infer water content have received the most attention. The ability of electromagnetic waves to determine characteristics of porous media has been recognized for most of the last century and earlier (Maxwell, 1881;Fricke, 1924;Velick and Gorin, 1940;Fricke, 1952;Thevanayagam, 1995), while the identification of the most effective measurement frequencies has been more recent (Rinaldi and Francisca, 1999). Because of the measurement ease and datalogging capabilities, TDR and capacitance measurements are increasingly becoming the method of choice.…”

Section: Introductionmentioning

confidence: 99%

Frequency, electrical conductivity and temperature analysis of a low-cost capacitance soil moisture sensor

Kizito

Campbell

et al. 2008

Journal of Hydrology

294

221

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“…The measured data were also compared to the relationship described by Maxwell and Frick (2,7,12). This expression deals with the resistivity of a medium in which particles of different resistivity are suspended.…”

Section: Resultsmentioning

confidence: 99%

“…The resistivity, p, is a material constant. Considering blood as a suspension of blood cells in plasma, overall resistivity can be expressed in terms of one, resistivity and volume relation of the cells and plasma and, two, a factor dependent on the shape of the suspended particles (2,7,12 …”

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confidence: 99%

Relation Between Blood Resistivity and Hematocrit in Fresh Human Fetal Blood

1981

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SummaryThis study determined the relation between hematocrit and resistivity of fetal blood and compared it with values obtained in similar studies on adult blood. Both exponential and MaxwellFrick-estimatnd relationships were calculated and compared. The results indicate that there is no significant difference between resistivity in adult and fetal blood. The best relation between blood resistivity and fetal hematocrit is obtained by using the MaxwellFrick estimated curve calculated in the following manner: where h = H/100 (H = hematocrit). SpeculationHematocrit varies over a wide range during the newborn period. Accurate knowledge of resistivity-hematocrit relationships over the entire hematocrit range is essential whenever blood resistivities are to be estimated from hematocrit values. This study reveals that a better correlation is obtained when using the Maxwell-Frick model instead of the ordinary exponential model. Thus, a tool is offered to improve the accuracy of the impedance cardiography method in newborns.The need for noninvasive methods in measuring physiologic and pathophysiologic conditions and courses in the newborn baby is evident.Impedance cardiography, one method to measure the cardiac stroke volume in healthy adults, was developed by Kubicek et al. (5). The ability of the method to measure pulmonary blood flow in the presence of left to right shunt in children was described by Lababidi et al. (6). The cardiac stroke volume is calculated according to the formuladeveloped by Kubicek et al. where SV = cardiac stroke volume in ml; p = blood resistivity in ohm cm; L = distance between the detecting inner electrodes in cm; zo = basal transthoracic impedance in ohm; dz/dt = minimum first derivative in ohm/s; T = ventricular ejection time in sec. The resistivity, p, is a material constant. Considering blood as a suspension of blood cells in plasma, overall resistivity can be expressed in terms of one, resistivity and volume relation of the cells and plasma and, two, a factor dependent on the shape of the suspended particles (2,7,12 MATERIALS AND METHODSA conductivity cell filled with human fetal umbilical cord blood, never older than 24 hr, was used for the measurements. The cord blood was collected immediately after delivery. To avoid clotting, heparin (5000 IU/ml) was added to the blood samples to yield an amount of 1 m1/10 ml blood. This amount of heparin had no significant influence on the resistivity (see below). The conductivity cell was placed in a water-bath maintained at 37OC and rotated to prevent the cells from settling. To make sure that the blood sample had reached a stable temperature, resistivity values were recorded only after remaining stable for at least 5 min. The low hematocrit values were created by diluting the blood samples with plasma from adults.The conductivity cell (Fig. 1) is the same as the one described by Axenborg (1) and essentially the same as the one described by Geddes and Da Costa (3). It consists of a syringe equipped with two-plane parallel stainless steel electr...

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The Electrical Conductance of Suspensions of Ellipsoids and Its Relation to the Study of Avian Erythrocytes

Cited by 91 publications

References 5 publications

Investigations into Coulter Sizing of Biological Particles; Theoretical Background and Instrumental Improvements

Investigations into Coulter Sizing of Biological Particles; Theoretical Background and Instrumental Improvements

Frequency, electrical conductivity and temperature analysis of a low-cost capacitance soil moisture sensor

Relation Between Blood Resistivity and Hematocrit in Fresh Human Fetal Blood

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