scholarly journals THE ELECTRIC IMPEDANCE OF HEMOLYZED SUSPENSIONS OF MAMMALIAN ERYTHROCYTES

1935 ◽  
Vol 18 (6) ◽  
pp. 821-836 ◽  
Author(s):  
Hugo Fricke ◽  
Howard J. Curtis
Keyword(s):  
Frequency Dependence ◽  
Electric Current ◽  
Sodium Taurocholate ◽  
Similar Type ◽  
Surface Resistivity ◽  
Electric Properties ◽  
Electric Impedance ◽  
Freezing And Thawing ◽  
Low Frequencies ◽  
Type Of Injury

This paper is concerned with the changes in the electric surface capacity and surface resistivity of the membrane surrounding the mammalian red corpuscle, as a result of various types of hemolysis. In the case of hemolysis with water, the cells swell with no apparent change in the electric properties of the membrane. They then hemolyze, but the membrane persists, although showing evidence of injury, as indicated by a change in the frequency dependence of its capacity and resistivity at low frequencies. The fact that a change of the frequency dependence takes place shows that the injury cannot be due merely to a rupture in the membrane, but must be due to changes in the properties (increased permeability) of the membrane as a whole. With chemical lysins (saponin, complement and amboceptor, digitonin, sodium taurocholate) a similar type of injury to the membranes of a certain number of the corpuscles takes place, to an increasing extent as the concentration of lysin is increased. The rest of the corpuscles become completely permeable to the electric current, and as the amount of lysin is increased, this number of completely permeable corpuscles increases until all are affected. This change, presumably associated with a disintegration of the corpuscle membrane, is referred to as stromatolysis, and the method gives a quantitative means of determining percentage stromatolysis. For lysis by freezing and thawing, the results obtained indicate this type of lysis to be different from that of the others studied.

scholarly journals Feasibility of Using Electrical Impedance Spectroscopy for Assessing Biological Cell Damage during Freezing and Thawing

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4129
Author(s):  
Sisay Mebre Abie ◽  
Ørjan Grøttem Martinsen ◽  
Bjørg Egelandsdal ◽  
Jie Hou ◽  
Frøydis Bjerke ◽  
...  
Keyword(s):  
Phase Angle ◽  
Short Term Memory ◽  
Cell Damage ◽  
Electrical Impedance Spectroscopy ◽  
Electric Impedance ◽  
Freezing And Thawing ◽  
Short Term ◽  
Long Short Term Memory ◽  
Impedance Parameters ◽  
Deep Learning Model

This study was performed to test bioimpedance as a tool to detect the effect of different thawing methods on meat quality to aid in the eventual creation of an electric impedance-based food quality monitoring system. The electric impedance was measured for fresh pork, thawed pork, and during quick and slow thawing. A clear difference was observed between fresh and thawed samples for both impedance parameters. Impedance was different between the fresh and the frozen-thawed samples, but there were no impedance differences between frozen-thawed samples and the ones that were frozen-thawed and then stored at +3 °C for an additional 16 h after thawing. The phase angle was also different between fresh and the frozen-thawed samples. At high frequency, there were small, but clear phase angle differences between frozen-thawed samples and the samples that were frozen-thawed and subsequently stored for more than 16 h at +3 °C. Furthermore, the deep learning model LSTM-RNN (long short-term memory recurrent neural network) was found to be a promising way to classify the different methods of thawing.

ON THE DIELECTRIC BEHAVIOR OF LiCo3/5Fe2/5VO4 CERAMICS

2010 ◽  
Vol 24 (07) ◽  
pp. 665-670
Author(s):  
MOTI RAM
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Frequency Dependence ◽  
Chemical Method ◽  
Arrhenius Plot ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Low Frequencies ◽  
Different Temperatures ◽  
Tan Δ

The LiCo 3/5 Fe 2/5 VO 4 ceramics has been fabricated by solution-based chemical method. Frequency dependence of the dielectric constant (εr) at different temperatures exhibits a dispersive behavior at low frequencies. Temperature dependence of εr at different frequencies indicates the dielectric anomalies in εr at Tc (transition temperature) = 190°C, 223°C, 263°C and 283°C with (εr) max ~ 5370, 1976, 690 and 429 for 1, 10, 50 and 100 kHz, respectively. Frequency dependence of tangent loss ( tan δ) at different temperatures indicates the presence of dielectric relaxation in the material. The value of activation energy estimated from the Arrhenius plot of log (τd) with 103/T is ~(0.396 ± 0.012) eV.

Low-frequency respiratory mechanical impedance in the rat

1987 ◽  
Vol 63 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Z. Hantos ◽  
B. Daroczy ◽  
B. Suki ◽  
S. Nagy
Keyword(s):  
Frequency Dependence ◽  
Chest Wall ◽  
Low Frequency ◽  
Mechanical Impedance ◽  
Total Resistance ◽  
Low Frequencies ◽  
Chest Wall Compliance ◽  
Before And After ◽  
Airway Opening ◽  
Wall Compliance

modified forced oscillatory technique was used to determine the respiratory mechanical impedances in anesthetized, paralyzed rats between 0.25 and 10 Hz. From the total respiratory (Zrs) and pulmonary impedance (ZL), measured with pseudorandom oscillations applied at the airway opening before and after thoracotomy, respectively, the chest wall impedance (ZW) was calculated as ZW = Zrs - ZL. The pulmonary (RL) and chest wall resistances were both markedly frequency dependent: between 0.25 and 2 Hz they contributed equally to the total resistance falling from 81.4 +/- 18.3 (SD) at 0.25 Hz to 27.1 +/- 1.7 kPa.l–1 X s at 2 Hz. The pulmonary compliance (CL) decreased mildly, from 2.78 +/- 0.44 at 0.25 Hz to 2.36 +/- 0.39 ml/kPa at 2 Hz, and then increased at higher frequencies, whereas the chest wall compliance declined monotonously from 4.19 +/- 0.88 at 0.25 Hz to 1.93 +/- 0.14 ml/kPa at 10 Hz. Although the frequency dependence of ZW can be interpreted on the basis of parallel inhomogeneities alone, the sharp fall in RL together with the relatively constant CL suggests that at low frequencies significant losses are imposed by the non-Newtonian resistive properties of the lung tissue.

Three-Dimensional Organization of Otolith-Ocular Reflexes in Rhesus Monkeys. III. Responses to Translation

1998 ◽  
Vol 80 (2) ◽  
pp. 680-695 ◽  
Author(s):  
Dora E. Angelaki
Keyword(s):  
Frequency Dependence ◽  
Brain Stem ◽  
Rhesus Monkeys ◽  
Three Dimensional ◽  
Head Orientation ◽  
Frequency Range ◽  
Low Frequencies ◽  
Similar Frequency ◽  
Response Sensitivity ◽  
Torsional Response

Angelaki, Dora E. Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. III. Responses to translation. J. Neurophysiol. 80: 680–695, 1998. The three-dimensional (3-D) properties of the translational vestibulo-ocular reflexes (translational VORs) during lateral and fore-aft oscillations in complete darkness were studied in rhesus monkeys at frequencies between 0.16 and 25 Hz. In addition, constant velocity off-vertical axis rotations extended the frequency range to 0.02 Hz. During lateral motion, horizontal responses were in phase with linear velocity in the frequency range of 2–10 Hz. At both lower and higher frequencies, phase lags were introduced. Torsional response phase changed more than 180° in the tested frequency range such that torsional eye movements, which could be regarded as compensatory to “an apparent roll tilt” at the lowest frequencies, became anticompensatory at all frequencies above ∼1 Hz. These results suggest two functionally different frequency bandwidths for the translational VORs. In the low-frequency spectrum (≪0.5 Hz), horizontal responses compensatory to translation are small and high-pass-filtered whereas torsional response sensitivity is relatively frequency independent. At higher frequencies however, both horizontal and torsional response sensitivity and phase exhibit a similar frequency dependence, suggesting a common role during head translation. During up-down motion, vertical responses were in phase with translational velocity at 3–5 Hz but phase leads progressively increased for lower frequencies (>90° at frequencies <0.2 Hz). No consistent dependence on static head orientation was observed for the vertical response components during up-down motion and the horizontal and torsional response components during lateral translation. The frequency response characteristics of the translational VORs were fitted by “periphery/brain stem” functions that related the linear acceleration input, transduced by primary otolith afferents, to the velocity signals providing the input to the velocity-to-position neural integrator and the oculomotor plant. The lowest-order, best-fit periphery/brain stem model that approximated the frequency dependence of the data consisted of a second order transfer function with two alternating poles (at 0.4 and 7.2 Hz) and zeros (at 0.035 and 3.4 Hz). In addition to clearly differentiator dynamics at low frequencies (less than ∼0.5 Hz), there was no frequency bandwidth where the periphery/brain stem function could be approximated by an integrator, as previously suggested. In this scheme, the oculomotor plant dynamics are assumed to perform the necessary high-frequency integration as required by the reflex. The detailed frequency dependence of the data could only be precisely described by higher order functions with nonminimum phase characteristics that preclude simple filtering of afferent inputs and might be suggestive of distributed spatiotemporal processing of otolith signals in the translational VORs.

scholarly journals CT2A Cell Viability Modulated by Electromagnetic Fields at Extremely Low Frequency under No Thermal Effects

2019 ◽  
Vol 21 (1) ◽  
pp. 152 ◽  
Author(s):  
Olga García-Minguillán ◽  
Raquel Prous ◽  
Maria del Carmen Ramirez-Castillejo ◽  
Ceferino Maestú
Keyword(s):  
Cell Viability ◽  
Frequency Dependence ◽  
Electromagnetic Fields ◽  
Thermal Effects ◽  
Low Frequency ◽  
Human Beings ◽  
Cellular Mechanisms ◽  
Low Frequencies ◽  
Hsp90 Expression

The effects produced by electromagnetic fields (EMFs) on human beings at extremely low frequencies (ELFs) have being investigated in the past years, across in vitro studies, using different cell lines. Nevertheless, the effects produced on cells are not clarified, and the cellular mechanisms and cell-signaling processes involved are still unknown. This situation has resulted in a division among the scientific community about the adequacy of the recommended level of exposure. In this sense, we consider that it is necessary to develop long-term exposure studies and check if the recommended levels of EMFs are under thermal effects. Hence, we exposed CT2A cells to different EMFs at different ELFs at short and long times. Our results showed frequency dependence in CT2A exposed during 24 h to a small EMF of 30 μT equal to those originated by the Earth and frequency dependence after the exposure during seven days to an EMF of 100 µT at different ELFs. Particularly, our results showed a remarkable cell viability decrease of CT2A cells exposed to EMFs of 30 Hz. Nevertheless, after analyzing the thermal effects in terms of HSP90 expression, we did not find thermal damages related to the differences in cell viability, so other crucial cellular mechanism should be involved.

On: “Frequency‐independent background internal friction in heterogeneous solids” by Baxter H. Armstrong (GEOPHYSICS, June 1980, p. 1042–1054).

Geophysics ◽  
1981 ◽  
Vol 46 (9) ◽  
pp. 1314-1314 ◽  
Author(s):  
Gábor Korvin
Keyword(s):  
Internal Friction ◽  
Frequency Dependence ◽  
Attenuation Coefficient ◽  
Thermal Conduction ◽  
Heterogeneous Solids ◽  
Low Frequencies ◽  
Novel Approach ◽  
Frequency Independent ◽  
Inherent Frequency

In his recent paper Dr. Armstrong proposes a novel approach based on considerations of thermal conduction and thermoelastic dissipation to explain the observed nearly constant Q behavior toward low frequencies in randomly heterogeneous solids. I feel, however, the fluctuation coefficient R defined by his equation (22) does have an inherent frequency dependence introduced through the [Formula: see text] factors so that the attenuation coefficient A might be a more complicated function of frequency than suggested by equation (24).

scholarly journals ELECTRIC IMPEDANCE OF ASTERIAS EGGS

1936 ◽  
Vol 19 (4) ◽  
pp. 609-623 ◽  
Author(s):  
Kenneth S. Cole ◽  
Robert H. Cole
Keyword(s):  
Plasma Membrane ◽  
Sea Water ◽  
Specific Resistance ◽  
Surface Conductance ◽  
Electric Impedance ◽  
High Concentration ◽  
Low Frequencies ◽  
Definite Evidence ◽  
Asterias Forbesi ◽  
Current Resistance

The alternating current resistance and capacity of suspensions of unfertilized eggs of Asterias forbesi have been measured at frequencies from one thousand to sixteen million cycles per second. The plasma membrane of the egg has a static capacity of 1.10µf/cm.2 which is practically independent of frequency. The suspensions show a capacity dependent on frequency at low frequencies which may be attributable to surface conductance. The specific resistance of the cytoplasm is between 136 and 225 ohm cm. (4 to 7 times sea water), indicating a relatively high concentration of non-electrolytes. At frequencies above one million cycles there is definite evidence of another element of which the nucleus is presumably a part.

scholarly journals Efficiency Analysis and Application of Improved Method for Heterogeneous Liquids Quality Assessing by Impedance Components

2019 ◽  
pp. 48-54
Author(s):  
A. Dolzhanskiy ◽  
Ye. Kolot
Keyword(s):  
Electrical Properties ◽  
Electric Current ◽  
Fermented Milk ◽  
Measuring Instruments ◽  
Separate Determination ◽  
Milk Product ◽  
Low Frequencies ◽  
Warburg Impedance ◽  
Subsequent Calculation ◽  
Model Components

Parameters of the total electrical resistance (impedance) are often used for substances properties identification, in particular, for heterogeneous liquids. In such conditions, the quality of the product is compared with the measured impedance (or full admittance) on alternating current [7, 8]. To do this, the industrial meters (RLC-meters), based on equivalent circuits, for example, in accordance with the «Warburg impedance scheme», are used. The disadvantages of such measurement tools are the uncertainty of the measuring circuit model components, the choice limitations of electrical parameters measuring means with the necessary sensitivity, as well as the high cost. Previously, the authors developed a new method of separate determination of active and capacitive impedance components for a heterogeneous fluid. This method is based on measuring at two close frequencies the levels of electric current and voltage with the subsequent calculation of the impedance components by a certain algorithm [1]. It is taken into account that the electrical properties of suspensions are usually caused by several types of charge carriers and depend a lot on the measurement conditions, in particular, the type (constant or alternating) and frequency of the electric current (6)…(8) [2, 3]. A new theoretical analysis and comparison of its results (9)…(11) with experimental data to determine the electrical properties of a water-graphite suspension (Table 1) revealed that the sensitivity of one of the impedance components (active or capacitive) to changes in a specific fluid property is higher than the total impedance. The experimental dependencies of the impedance components of a model fermented milk product on its fat content at low frequencies (up to 400 Hz) and voltage (up to 5 V) of electric current are presented (Figures 2, 3). These data confirmed the possibility of practical use of the design results for rapid quality assessment of various electrically conductive heterogeneous liquids with the necessary sensitivity and accuracy of measuring instruments.

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