Low Amplitude Electric Fields Research Articles

Amplitude modulation in surfactant and polymer-based water-in-oil emulsions: A novel approach to enhance separation rate and mitigate chaining effects

Oil wells can eventually run out of oil if used for an extended period. Various polymers and surfactants are used to enhance oil recovery to extend the useful life of a well and improve the recovery process. These chemicals are added to make the extraction process easier. However, the emulsion that results from this process can be difficult to break down because of the added chemicals. Therefore, special measures are necessary to recover the crude oil effectively by breaking the emulsion. Electrocoalescers are specialized large-scale units designed for the purpose of separating water from emulsions. Improving the performance of an electrocoalescer involves achieving faster dehydration of the emulsion while ensuring safe operation. This means increasing the rate of water separation without compromising safety. The proposed technique aims to improve separation by modulation of the AC electric field. This modulation consists of a step with a high-amplitude electric field, followed by a step with a low-amplitude electric field, then repeated. This work involves a study of four types of emulsions that were used: (1) water-in-oil emulsion without surfactant/polymer, (2) polymer-stabilized water-in-oil emulsion, (3) surfactant stabilized water-in-oil emulsion, and (4) surfactant and polymer mixed-stabilized water-in-oil emulsion. The electrocoalescence process has faster kinetics compared to conventional methods. Modulation facilitates drop chaining during high voltage and effective coalescence during low voltage. It has been observed that an increase in the conductivity of the dispersed phase can lead to an increase in non-coalescence. The surfactant (SDS) and polymer (HPAM) mixture become more challenging to separate.

Regulation of endothelial MAPK/ERK signalling and capillary morphogenesis by low-amplitude electric field

Low-amplitude electric field (EF) is an important component of wound-healing response and can promote vascular tissue repair; however, the mechanisms of action on endothelium remain unclear. We hypothesized that physiological amplitude EF regulates angiogenic response of microvascular endothelial cells via activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway. A custom set-up allowed non-thermal application of EF of high (7.5 GHz) and low (60 Hz) frequency. Cell responses following up to 24 h of EF exposure, including proliferation and apoptosis, capillary morphogenesis, vascular endothelial growth factor (VEGF) expression and MAPK pathways activation were quantified. A db/db mouse model of diabetic wound healing was used for in vivo validation. High-frequency EF enhanced capillary morphogenesis, VEGF release, MEK-cRaf complex formation, MEK and ERK phosphorylation, whereas no MAPK/JNK and MAPK/p38 pathways activation was observed. The endothelial response to EF did not require VEGF binding to VEGFR2 receptor. EF-induced MEK phosphorylation was reversed in the presence of MEK and Ca(2+) inhibitors, reduced by endothelial nitric oxide synthase inhibition, and did not depend on PI3K pathway activation. The results provide evidence for a novel intracellular mechanism for EF regulation of endothelial angiogenic response via frequency-sensitive MAPK/ERK pathway activation, with important implications for EF-based therapies for vascular tissue regeneration.

Electric field modulation of long-term plastic effects

Event Abstract Back to Event Electric field modulation of long-term plastic effects Belen Lafon1*, Davide Reato1, Asif Rahman1, Marom Bikson1 and Lucas C. Parra1 1 City College of the City University of New York, United States Transcranial electrical stimulation in humans can lead to electric fields of at most 1V/m on the cortical surface. This may polarize cell membranes by a fraction of a milivolt. While these intensities seem very small, there are a number of in vitro experiments explaining the basic mechanisms by which such low-amplitude electric fields may nevertheless acutely alter neuronal activity, both at the single cell and at the network level . However, the long-term plastic effects which have been repeatedly observed clinically are less understood. Here we are particularly interested in the effects of slow-oscillating stimulation during sleep which were shown to boost the consolidation of hippocampus-dependent declarative memory. How synaptic connections are modified resulting in a memory improvement is still unknown. Currently, two main complementary hypotheses exist regarding consolidation of memory during sleep. The synaptic homeostasis hypothesis conjunctures that consolidation is in part a result of synaptic downscaling that improves the signal-to-noise ratio for all synapses that were potentiated during prior waking experiences. The active system consolidation hypothesis proposes an active consolidation process where learning-specific synaptic connections are strengthened by means of increased plasticity-related immediate early gene transcription and induction of LTP. Slow-oscillating stimulation might be improving memory consolidation by means of modulating synaptic downscaling and/or learning-specific synaptic connections. Current results of our group show that this low-amplitude fields induced an effect on the homeostatic downscaling of endogenous slow-waves during sleep. However, the modulation LTP processes related to the potentiation of learning related synapses has not yet been studied for such fields. Previous studies show that electrical stimulation coupled with ongoing activity in the brain induces plasticity, here we will focus on the modulation of LTP processes while applying acutely several low-amplitude field configurations. Thus linking the long-term behavioral effects with acute electrical stimulation. References Nature. 2006 Nov 30;444(7119):610-3. Epub 2006 Nov 5. Boosting slow oscillations during sleep potentiates memory. Marshall L, Helgadóttir H, Mölle M, Born J. Sleep Med Rev. 2006 Feb;10(1):49-62. Epub 2005 Dec 22. Sleep function and synaptic homeostasis. Tononi G, Cirelli C. Nat Rev Neurosci. 2010 Feb;11(2):114-26. Epub 2010 Jan 4. The memory function of sleep. Diekelmann S, Born J. Keywords: plasticity, Electrical Stimulation, Sleep, long term potentiation, HIPPOCAMPUS AND MEMORY Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012. Presentation Type: Poster Topic: Learning, plasticity, memory Citation: Lafon B, Reato D, Rahman A, Bikson M and Parra LC (2012). Electric field modulation of long-term plastic effects. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00035 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 18 Jun 2012; Published Online: 12 Sep 2012. * Correspondence: Miss. Belen Lafon, City College of the City University of New York, New York, United States, belulafon@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Belen Lafon Davide Reato Asif Rahman Marom Bikson Lucas C Parra Google Belen Lafon Davide Reato Asif Rahman Marom Bikson Lucas C Parra Google Scholar Belen Lafon Davide Reato Asif Rahman Marom Bikson Lucas C Parra PubMed Belen Lafon Davide Reato Asif Rahman Marom Bikson Lucas C Parra Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

A kind of two-dimensional electroconvection at ultralow electric frequency

We report a kind of two-dimensional (2D) electroconvection (EC) domain observed in a negative dielectric anisotropy nematic liquid crystal (LC) in a parallel-rubbed alignment cell. The domain is excited by an ac electric field with ultralow frequency, and can be transformed into a one-dimensional (1D) EC domain at low amplitude electric fields. We conclude that the 1D domain is a kind of Williams domain, while the 2D domain is induced by flexoelectric effect, the corresponding 2D texture coming from superposition of two sets of symmetrical 1D stripes oblique to the initial LC orientation.

Effects of ELF electric field on proliferation of mouse osteoblastic cells

MTT method and flow cytometry were used to detect the proliferation of osteoblastic cells after the cells were exposed to the low frequency, low amplitude electric field. The results showed that the cells exposed to the electric field of 10 Hz, 200 mV cm −1 for 20 min grew 59% more rapidly than the control cells, and also 52.94% more cells were in the S-phase. A fluorescence technique was used to measure the membrane fluidity and the change of the Ca 2+ concentration inside the cells ([Ca 2+] i), in order to study mechanism of the influence on cell proliferation after the cells were exposed to electric field. Our results show that the R value increased 27.38% compared to the control after the cells were treated with electric field of 10 Hz, 200 mV cm −1. The cell membrane viscosity increased 19.57% compared to the control after the treatment.

Electrical conductivity of α-LiIO 3 acid type crystals at 1 kHz

The temperature dependence of the electrical conductivity of α-LiIO 3 acid type crystals is studied. By applying a very low amplitude electric field at 1 kHz and performing a continuous sampling of measurements, differences, reproducible for all the investigated samples, appeared between the first and subsequent heatings The anomalies occurring during the first heating are attributed mainly to inclusions of mother liquor, HIO 3 and Li 1-xH xIO 3. The ‘intrinsic’ conductivity is measured after a first annealing at about 470 K; the activation energies are then calculated.