scholarly journals On the Impact of Electrostatic Correlations on the Double-Layer Polarization of a Spherical Particle in an Alternating Current Field

Langmuir ◽  
2018 ◽  
Vol 34 (19) ◽  
pp. 5592-5599 ◽  
Author(s):  
Elaheh Alidoosti ◽  
Hui Zhao
Keyword(s):  
Spherical Particle ◽  
Double Layer ◽  
Alternating Current ◽  
Current Field ◽  
The Impact

scholarly journals Numerical simulation in alternating current field measurement inducer design

2017 ◽  
Author(s):  
Zhixiong Zhou ◽  
Wenpei Zheng
Keyword(s):  
Numerical Simulation ◽  
Field Measurement ◽  
Alternating Current ◽  
Current Field

Investigation of optimal time-domain feature for non-surface defect detection through a pulsed alternating current field measurement technique

2017 ◽  
Vol 29 (1) ◽  
pp. 015601 ◽  
Author(s):  
Jiuhao Ge ◽  
Wei Li ◽  
Guoming Chen ◽  
Xiaokang Yin ◽  
Jian Liu ◽  
...  
Keyword(s):  
Defect Detection ◽  
Measurement Technique ◽  
Time Domain ◽  
Field Measurement ◽  
Surface Defect ◽  
Alternating Current ◽  
Optimal Time ◽  
Current Field ◽  
Surface Defect Detection

scholarly journals A Prospective Study of the Impact of Transcranial Alternating Current Stimulation on EEG Correlates of Somatosensory Perception

2018 ◽  
Vol 9 ◽  
Author(s):  
Danielle D. Sliva ◽  
Christopher J. Black ◽  
Paul Bowary ◽  
Uday Agrawal ◽  
Juan F. Santoyo ◽  
...  
Keyword(s):  
Prospective Study ◽  
Alternating Current ◽  
Transcranial Alternating Current Stimulation ◽  
A Prospective Study ◽  
The Impact

scholarly journals The influence of dielectric decrement on electrokinetics

2013 ◽  
Vol 724 ◽  
pp. 69-94 ◽  
Author(s):  
Hui Zhao ◽  
Shengjie Zhai
Keyword(s):  
Asymptotic Analysis ◽  
Double Layer ◽  
Debye Length ◽  
Charged Surface ◽  
Ion Specificity ◽  
Zeta Potentials ◽  
Condensed Layer ◽  
The Impact ◽  
Surface Conduction ◽  
Electro Osmotic Flow

AbstractWe treat the dielectric decrement induced by excess ion polarization as a source of ion specificity and explore its impact on electrokinetics. We employ a modified Poisson–Nernst–Planck (PNP) model accounting for the dielectric decrement. The dielectric decrement is determined by the excess-ion-polarization parameter $\alpha $ and when $\alpha = 0$ the standard PNP model is recovered. Our model shows that ions saturate at large zeta potentials $(\zeta )$. Because of ion saturation, a condensed counterion layer forms adjacent to the charged surface, introducing a new length scale, the thickness of the condensed layer $({l}_{c} )$. For the electro-osmotic mobility, the dielectric decrement weakens the electro-osmotic flow owing to the decrease of the dielectric permittivity. At large $\zeta $, when $\alpha \not = 0$, the electro-osmotic mobility is found to be proportional to $\zeta / 2$, in contrast to $\zeta $ as predicted by the standard PNP model. This is attributed to ion saturation at large $\zeta $. In terms of the electrophoretic mobility ${M}_{e} $, we carry out both an asymptotic analysis in the thin-double-layer limit and solve the full modified PNP model to compute ${M}_{e} $. Our analysis reveals that the impact of the dielectric decrement is intriguing. At small and moderate $\zeta ~({\lt }6kT/ e)$, the dielectric decrement decreases ${M}_{e} $ with increasing $\alpha $. At large $\zeta $, it is known that the surface conduction becomes significant and plays an important role in determining ${M}_{e} $. It is observed that the dielectric decrement effectively reduces the surface conduction. Hence in stark contrast, ${M}_{e} $ increases as $\alpha $ increases. Our predictions of the contrast dependence of the mobility on $\alpha $ at different zeta potentials qualitatively agree with experimental results on the dependence of the mobility among ions and provide a possible explanation for such ion specificity. Finally, the comparisons between the thin-double-layer asymptotic analysis and the full simulations of the modified PNP model suggest that at large $\zeta $ the validity of the thin-double-layer approximation is determined by ${l}_{c} $ rather than the traditional Debye length.

scholarly journals Biasing the Perception of Spoken Words with Transcranial Alternating Current Stimulation

2020 ◽  
Vol 32 (8) ◽  
pp. 1428-1437
Author(s):  
Anne Kösem ◽  
Hans Rutger Bosker ◽  
Ole Jensen ◽  
Peter Hagoort ◽  
Lars Riecke
Keyword(s):  
Speech Processing ◽  
Alternating Current ◽  
Spoken Word ◽  
Word Perception ◽  
Transcranial Alternating Current Stimulation ◽  
Neural Entrainment ◽  
The Difference ◽  
Auditory Cortices ◽  
Speech Segments ◽  
The Impact

Recent neuroimaging evidence suggests that the frequency of entrained oscillations in auditory cortices influences the perceived duration of speech segments, impacting word perception [Kösem, A., Bosker, H. R., Takashima, A., Meyer, A., Jensen, O., & Hagoort, P. Neural entrainment determines the words we hear. Current Biology, 28, 2867–2875, 2018]. We further tested the causal influence of neural entrainment frequency during speech processing, by manipulating entrainment with continuous transcranial alternating current stimulation (tACS) at distinct oscillatory frequencies (3 and 5.5 Hz) above the auditory cortices. Dutch participants listened to speech and were asked to report their percept of a target Dutch word, which contained a vowel with an ambiguous duration. Target words were presented either in isolation (first experiment) or at the end of spoken sentences (second experiment). We predicted that the tACS frequency would influence neural entrainment and therewith how speech is perceptually sampled, leading to a perceptual overestimation or underestimation of the vowel's duration. Whereas results from Experiment 1 did not confirm this prediction, results from Experiment 2 suggested a small effect of tACS frequency on target word perception: Faster tACS leads to more long-vowel word percepts, in line with the previous neuroimaging findings. Importantly, the difference in word perception induced by the different tACS frequencies was significantly larger in Experiment 1 versus Experiment 2, suggesting that the impact of tACS is dependent on the sensory context. tACS may have a stronger effect on spoken word perception when the words are presented in continuous speech as compared to when they are isolated, potentially because prior (stimulus-induced) entrainment of brain oscillations might be a prerequisite for tACS to be effective.

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