Quasi-Static Electrorheological Properties of Hematite/Silicone Oil Suspensions under DC Electric Fields

Langmuir ◽  
2005 ◽  
Vol 21 (11) ◽  
pp. 4896-4903 ◽  
Author(s):  
M. J. Espin ◽  
A. V. Delgado ◽  
J. Płocharski
Keyword(s):  
Electric Fields ◽  
Silicone Oil ◽  
Electrorheological Properties ◽  
Dc Electric Fields

Electrorheological Properties of Suspensions Based on Polyaniline-montmorillonite Clay Nanocomposite

2002 ◽  
Vol 17 (6) ◽  
pp. 1513-1519 ◽  
Author(s):  
Jun Lu ◽  
Xiaopeng Zhao
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Yield Stress ◽  
Electric Fields ◽  
High Dielectric Constant ◽  
Silicone Oil ◽  
Transmission Electron ◽  
High Dielectric ◽  
Er Fluid ◽  
Electrorheological Properties

It is thought that high-dielectric constant, suitable conductivity, and dielectric loss dominate electrorheological (ER) effects. According to this viewpoint, the polyaniline/montmorillonite nanocomposite (PANI-MMT) particles with high-dielectric constant and suitable conductivity were synthesized by an emulsion intercalation method. The electrorheological properties of the suspensions of PANI-MMT particles in silicone oil have been investigated under direct current electric fields. At room temperature, it was found that the yield stress of PANI-MMT ER fluid was 7.19 kPa in 3 kV/mm, which is much higher than that of pure polyaniline (PANI), that of pure montmorillonite (MMT) as well as that of the mixture of polyaniline with clay (PANI+MMT). In the range of 10–100 °C, the yield stress changed only 6.5% with the variation of temperature. The sedimentation ratio of PANI-MMT ERF was about 98% after 60 days. The structure of PANI-MMT particles was characterized by infrared, x-ray diffraction (XRD), and transmission electron microscopy (TEM) spectrometry, respectively. The XRD spectra show that the inner layer distance of PANI-MMT can be enhanced to 1.52 nm when the PANI was inserted into the interlayer of MMT, whereas it is only 0.96 nm for free MMT. TEM shows that the diameter of PANI-MMT particles is about 100 nm. The dielectric constant of PANI-MMT nanocomposite was increased 5.5 times that of PANI and 2.7 times that of MMT, besides, the conductivity of PANI-MMT particle was increased about 8.5 times that of PANI at 1000 Hz. Meanwhile, the dielectric loss tangent can also be increased about 1.7 times that of PANI. It is apparent that the notable ER effect of PANI-MMT ER fluid was attributed to the prominent dielectric property of the polyaniline-montmorillonite nanocomposite particles.

Convergence effect of droplet coalescence under AC and pulsed DC electric fields

2021 ◽  
pp. 103776
Author(s):  
Xin Huang ◽  
Limin He ◽  
Xiaoming Luo ◽  
Ke Xu ◽  
Yuling Lü ◽  
...  
Keyword(s):  
Electric Fields ◽  
Droplet Coalescence ◽  
Pulsed Dc ◽  
Dc Electric Fields

Pulsed DC electric fields couple to natural NAD(P)H oscillations in HT-1080 fibrosarcoma cells

2001 ◽  
Vol 114 (8) ◽  
pp. 1515-1520 ◽  
Author(s):  
A.J. Rosenspire ◽  
A.L. Kindzelskii ◽  
H.R. Petty
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cell Function ◽  
Low Frequency ◽  
Reactive Oxygen Metabolites ◽  
Pulsed Dc ◽  
Fibrosarcoma Cells ◽  
Chemotactic Factors ◽  
Oxygen Metabolites ◽  
Dc Electric Fields

Previously, we have demonstrated that NAD(P)H levels in neutrophils and macrophages are oscillatory. We have also found that weak ultra low frequency AC or pulsed DC electric fields can resonate with, and increase the amplitude of, NAD(P)H oscillations in these cells. For these cells, increased NAD(P)H amplitudes directly signal changes in behavior in the absence of cytokines or chemotactic factors. Here, we have studied the effect of pulsed DC electric fields on HT-1080 fibrosarcoma cells. As in neutrophils and macrophages, NAD(P)H levels oscillate. We find that weak (~10(-)(5) V/m), but properly phased DC (pulsed) electric fields, resonate with NAD(P)H oscillations in polarized and migratory, but not spherical, HT-1080 cells. In this instance, electric field resonance signals an increase in HT-1080 pericellular proteolytic activity. Electric field resonance also triggers an immediate increase in the production of reactive oxygen metabolites. Under resonance conditions, we find evidence of DNA damage in HT-1080 cells in as little as 5 minutes. Thus the ability of external electric fields to effect cell function and physiology by acting on NAD(P)H oscillations is not restricted to cells of the hematopoietic lineage, but may be a universal property of many, if not all polarized and migratory eukaryotic cells.

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