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Henk P M Vijverberg - One of the best experts on this subject based on the ideXlab platform.
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allosteric potentiatIon of the 5 ht3 receptor mediated Ion Current in n1e 115 neuroblastoma cells by 5 hydroxyindole and analogues
Neuropharmacology, 1997Co-Authors: Johannes A Van Hooft, E Van Der Haar, Henk P M VijverbergAbstract:Abstract PotentiatIon of the 5-HT3 receptor-mediated Ion Current in mouse N1E-115 neuroblastoma cells by 5-hydroxyindole (5-OHi) and three analogues (5-aminoindole, catechol and indole) was examined using whole-cell voltage clamp and single channel patch clamp techniques. The substances tested enhanced the amplitude of the maximum 5-HT-evoked Ion Current by 12–30%. The rank order (at 1 mM) to potentiate the 5-HT-induced Current was: 5-OHi ≈5-aminoindole≈catechol>indole. The concentratIon-effect curve of 5-HT was shifted leftwards by 1 mM 5-OHi, resulting in a two-fold increase of the apparent affinity of 5-HT from 1.4 μM to 0.7 μM, without affecting the Hill coefficient. The time constant of reversal of activatIon of the 5-HT-induced Ion Current upon washout of the agonist was delayed by 1 mM 5-OHi from 4.0 sec to 12.8 sec. 5-HT3 receptor-gated single channel events in cell-attached patches in the presence and absence of 1 mM 5-OHi were indistinguishable, apart from a slight increase in the event frequency. The results suggest that 5-OHi and analogues potentiate the 5-HT3 receptor-mediated Ion Current by delaying agonist dissociatIon and thereby increase the probability of channel opening. From the increased apparent affinity of 5-HT and the non-surmountability of the potentiating effect, it is concluded that 5-OHi and analogues are allosteric modulators of 5-HT3 receptors. © 1997 Elsevier Science Ltd.
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interactIon between enantiomers of mianserin and org3770 at 5 ht3 receptors in cultured mouse neuroblastoma cells
Neuropharmacology, 1994Co-Authors: Andre R Kooyman, Ruud Zwart, P M L Vanderheijden, J A Van Hooft, Henk P M VijverbergAbstract:Abstract Stereoselective effects of mianserin and ORG3770 on serotonin 5-HT3 receptors in mouse neuroblastoma N1E-115 cells have been investigated in radioligand binding and in whole-cell voltage clamp experiments. The specific binding of [3H]GR65630 to 5-HT3 recognitIon sites in N1E-115 cell homogenates is reduced by mianserin and ORG3770 and their enantiomers. The p Ki values of the more potent (R)enantiomers of mianserin and ORG3770 are 8.44 and 8.62, respectively. The (R)enantiomers of mianserin and ORG3770 are 15 and 37 times more potent than their respective(S)enantiomers. The racemates are only 1.9 and 3.3 times less potent than the corresponding (R)enantiomers. In voltage clamp experiments the (R)enantiomers block the 5-hydroxytryptamine(5-HT)-induced Ion Current with pIC50 values of 8.52 for (R)mianserin and 8.26 for the (R)enantiomer of ORG3770. The (R)enantiomers of mianserin and ORG3770 are 24 and 145 times more potent in blocking the 5-HT-induced Ion Current than their respective (S)enantiomers. The racemates are 6 and 13 times less potent than the corresponding (R)enantiomers. In additIon, the block of 5-HT-induced Ion Current by the (R)enantiomer of ORG3770 is partially reversed by a low concentratIon of its (S)enantiomer. The results indicate that the two enantiomers block the 5-HT3 receptor-mediated Ion Current in a mutually dependent manner.
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5 hydroxyindole slows desensitizatIon of the 5 ht3 receptor mediated Ion Current in n1e 115 neuroblastoma cells
British Journal of Pharmacology, 1993Co-Authors: Andre R Kooyman, Johannes A Van Hooft, Henk P M VijverbergAbstract:Abstract Effects of 5-hydroxyindole (5-OHi) on 5-HT3 receptor-operated Ion Current were investigated in voltage-clamped N1E-115 neuroblastoma cells. In the presence of 1 mM 5-OHi, the amplitudes of inward Currents induced by the agonists 5-hydroxytryptamine (5-HT), 2-methyl-5-HT and dopamine were enhanced and desensitizatIon of the responses was markedly slowed down. The results indicate that 5-OHi selectively modifies the desensitizatIon of the 5-HT3 receptor-mediated Ion Current.
Robert W Dibble - One of the best experts on this subject based on the ideXlab platform.
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effect of electric fields on the Ion Current signals in a constant volume combustIon chamber
Proceedings of the Combustion Institute, 2019Co-Authors: Guangyu Dong, Robert W DibbleAbstract:Abstract Ion Current sensing has the potential to become a promising combustIon diagnostic technique for mass productive engines. In this paper, the effect of electric fields on Ion Current signals measured from a series of methane/air flames in a constant volume combustIon chamber (CVCC) is investigated both experimentally and numerically. Based on simultaneous flame Schlieren imaging and Ion Current measurement, the relatIon between the flame/electrodes contact area and the Ion Current signal waveform is explored under different electric field configuratIons. A CFD model, which incorporates flame plasma hydrodynamics, neutral/charged species reactIon kinetics and Ion-electric field interactIons, is constructed. The effect of the electric field on the Ion distributIon and the charged species flux are analyzed, and the signal amplitude and timing are well predicted under the equivalence ratio range of Ф = 0.7–1.1. Besides, the behavior of electrons, which is normally neglected in previous studies, is also analyzed in this work. The results show that it will affect the signal as well. The electron produced in the flame front zone can hardly diffuse into the pre-flame zone (
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study on the phase relatIon between Ion Current signal and combustIon phase in an hcci combustIon engine
Proceedings of the Combustion Institute, 2015Co-Authors: Guangyu Dong, Yulin Chen, Robert W DibbleAbstract:Abstract Ion sensing is a promising approach for cycle resolved combustIon phasing in HCCI engines. This paper investigates the fundamental processes affecting the phase difference (Pdelta) between Ion Current signal phase Ion50 and combustIon phase CA50 based on 2 numerical models. One model is used to explore fluid dynamic effects on an HCCI engine. The other model, a 10-zone model, is used to primarily explore the affecting mechanism on Pdelta. Both numerical analysis and experimental results of the IonizatIon process indicate that Pdelta is affected by both flame IonizatIon and fuel heat release process. For fuels with similar octane number (ON), such as gasoline (ON = 97) and ethanol (ON = 107), both the combustIon phase CA50 and the Ion Current signal phase Ion50 retard when the equivalence ratio Φ decreases. However, the CA50 for ethanol fuel retards moderately compared with the gasoline case since the CA50 for ethanol fuel is more sensitive to intake temperature T in rather than Φ . Then larger Pdelta values can be seen in ethanol fueled HCCI engine under lower Φ conditIons. For the fuels with different widely octane number, such as gasoline and diesel (ON = 0), their combustIon boundary conditIons are different in HCCI engines, they produce Ions at a different ratio. For diesel fuel, the Ion productIon rate is much lower due to the lower intake temperature and higher compressIon ratio. Under low Φ conditIons, the Ion Current signal cannot be observed at the beginning of Ion concentratIon increase in diesel fueled HCCI engines, and the Ion50 appears much later compared with the gasoline fueled HCCI engine. As a result, the values of Pdelta increase significantly in the diesel fueled HCCI engine.
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improving Ion Current of sparkplug Ion sensors in hcci combustIon using sodium potassium and cesium acetates experimental and numerical modeling
Proceedings of the Combustion Institute, 2015Co-Authors: Ryan H Butt, Robert W Dibble, Yulin Chen, John Hunter Mack, Samveg Saxena, J Y ChenAbstract:Abstract Measuring the Ion Current with a sparkplug Ion sensor in a homogeneous charge compressIon ignitIon (HCCI) engine can be used to investigate the Ion chemistry in the cylinders during combustIon. HCCI engines are similar to a well-stirred reactor and operate at lean equivalence ratios (ϕ). Under these conditIons, the Ion Current becomes increasingly indistinguishable from background noise. This paper investigates various fuel additive effects on Ion signal at low ϕ’s, determines side effects of metal acetate additIon, and validates a numerical model. The fuel additives added to ethanol were sodium acetate (NaOAc), potassium acetate (KOAc), and cesium acetate (CsOAc). ConcentratIon levels ranging from 0.5 to 4.9 mmol/L of metal acetate-in-ethanol are investigated over ϕ’s 0.11, 0.22, 0.28, and 0.32. The engine operated under naturally aspirated conditIons and maintained a constant timing of 2.5° after top-dead-center (ATDC) at the crank angle degree (CAD) where 50% of the heat release occurs (CA50). CsOAc consistently produced the strongest Ion signals, followed by KOAc and NaOAc, which NaOAc had the weakest effect on Ion signal. No distinguishable Ion signals were measured at ϕ = 0.11, but significant Ion signal improvements occurred at ϕ = 0.22 using the fuel additives. However, the additIon of the metal acetates decreased heat release rates (HRR) and peak cylinder pressures. Although CsOAc produced the largest signal improvements, it also had the largest decrease in HRR and peak cylinder pressure. AdditIonally, a single-zone engine model that simulates the chemical kinetics and Ion chemistry of KOAc additIon is presented and validated with the experimental results.
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combustIon timing in hcci engines determined by Ion sensor experimental and kinetic modeling
Proceedings of the Combustion Institute, 2005Co-Authors: P Mehresh, Jason S Souder, Daniel L Flowers, Uwe Riedel, Robert W DibbleAbstract:Abstract The Ion Current signal in homogenous charge compressIon ignitIon (HCCI) engines is studied. The aim of this research is to show that a measurable Ion Current exists even in the very lean combustIon (equivalence ratio ϕ = 0.35) in an HCCI engine. Numerical models using detailed chemical kinetics for propane combustIon, including kinetics for Ion formatIon, support the experimental findings. The effects of the equivalence ratio, the intake mixture temperature, and the applied bias voltage on the Ion signal are studied through a series of experiments. The findings are compared to the numerical model results. The research shows that an inexpensive Ion sensor may replace the expensive pressure transducers Currently used in HCCI engines. The Ion Current signal is very sensitive to the equivalence ratio of the intake fuel–air mixture. Through numerical modeling, the N2O mechanism is shown to be the significant source of Nitrogen Oxides (NOx) generatIon in HCCI combustIon.
Zuzanna S Siwy - One of the best experts on this subject based on the ideXlab platform.
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nanoprecipitatIon assisted Ion Current oscillatIons
Nature Nanotechnology, 2008Co-Authors: Matthew R Powell, Dragos Constantin, Michael Sullivan, Ivan Vlassiouk, Olivier Sudre, Craig C Martens, R S Eisenberg, Zuzanna S SiwyAbstract:Nanoscale pores exhibit transport properties that are not seen in micrometre-scale pores, such as increased Ionic concentratIons inside the pore relative to the bulk solutIon, Ionic selectivity and Ionic rectificatIon. These nanoscale effects are all caused by the presence of permanent surface charges on the walls of the pore. Here we report a new phenomenon in which the additIon of small amounts of divalent catIons to a buffered monovalent Ionic solutIon results in an oscillating Ionic Current through a conical nanopore. This behaviour is caused by the transient formatIon and redissolutIon of nanoprecipitates, which temporarily block the Ionic Current through the pore. The frequency and character of Ionic Current instabilities are regulated by the potential across the membrane and the chemistry of the precipitate. We discuss how oscillating nanopores could be used as model systems for studying nonlinear electrochemical processes and the early stages of crystallizatIon in sub-femtolitre volumes. Such nanopore systems might also form the basis for a stochastic sensor.
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poisson nernst planck model of Ion Current rectificatIon through a nanofluidic diode
Physical Review E, 2007Co-Authors: Dragos Constantin, Zuzanna S SiwyAbstract:We have investigated Ion Current rectificatIon properties of a recently prepared bipolar nanofluidic diode. This device is based on a single conically shaped nanopore in a polymer film whose pore walls contain a sharp boundary between positively and negatively charged regIons. A semiquantitative model that employs Poisson and Nernst-Planck equatIons predicts Current-voltage curves as well as Ionic concentratIons and electric potential distributIons in this system. We show that under certain conditIons the rectificatIon degree, defined as a ratio of Currents recorded at the same voltage but opposite polarities, can reach values of over 1000 at a voltage range . The role of thickness and positIon of the transitIon zone on the Ion Current rectificatIon is discussed as well. We also show that the rectificatIon degree scales with the applied voltage.
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Ion Current rectificatIon in nanopores and nanotubes with broken symmetry
Advanced Functional Materials, 2006Co-Authors: Zuzanna S SiwyAbstract:This article focuses on Ion transport through nanoporous systems with special emphasis on rectificatIon phenomena. The effect of Ion-Current rectificatIon is observed as asymmetric Current–voltage (I–V) curves, with the Current recorded for one voltage polarity higher than the Current recorded for the same absolute value of voltage of opposite polarity. This diode-like I–V curve indicates that there is a preferential directIon for Ion flow. Experimental evidence that Ion-Current rectificatIon is inherent to asymmetric, e.g., tapered, nanoporous systems with excess surface charge is provided and discussed. The fabricatIon and operatIon of asymmetric polymer nanopores, gold nanotubes, glass nanocapillaries, and silicon nanopores are presented. The possibility of tuning the directIon and extent of rectificatIon is discussed in detail. Theoretical models that have been developed to explain the Ion-Current rectificatIon effect are also presented.
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Ion Current rectificatIon in nanopores and nanotubes with broken symmetry
Advanced Functional Materials, 2006Co-Authors: Zuzanna S SiwyAbstract:This article focuses on Ion transport through nanoporous systems with special emphasis on rectificatIon phenomena. The effect of Ion-Current rectificatIon is observed as asymmetric Current–voltage (I–V) curves, with the Current recorded for one voltage polarity higher than the Current recorded for the same absolute value of voltage of opposite polarity. This diode-like I–V curve indicates that there is a preferential directIon for Ion flow. Experimental evidence that Ion-Current rectificatIon is inherent to asymmetric, e.g., tapered, nanoporous systems with excess surface charge is provided and discussed. The fabricatIon and operatIon of asymmetric polymer nanopores, gold nanotubes, glass nanocapillaries, and silicon nanopores are presented. The possibility of tuning the directIon and extent of rectificatIon is discussed in detail. Theoretical models that have been developed to explain the Ion-Current rectificatIon effect are also presented.
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conical nanotube Ion Current rectifiers the role of surface charge
Journal of the American Chemical Society, 2004Co-Authors: Zuzanna S Siwy, Elizabeth A Heins, Chad C Harrell, Punit Kohli, Charles R MartinAbstract:Ion channels are protein pores that span cell membranes and open and close in response to stimuli like changes in the transmembrane potential, binding of a ligand, or mechanical stress. When open, Ions pass through the pore, and hence across the cell membrane, and when closed, Ion-transport is precluded. Hence, these channels are nanodevices that have a Current-rectificatIon functIon. There is intense research effort aimed at understanding the molecular-level mechanism for this functIon. One approach for elucidating the mechanism is to construct a simple abiotic system that mimics this functIon and to use the mechanistic details of this mimic as a guide to understand the more complex biological channel. We describe here such an abiotic mimic: a synthetic membrane that contains a single conical gold nanotube. The advantage of this mimic is that the surface charge and chemistry of the nanotube wall can be varied, at will, by judicious choice of electrolyte or by thiol chemisorptIon. This has allowed us to make conical Au nanotubes that rectify the Ion Current and, just as importantly, to definitively elucidate the mechanism of this functIon.
Andre R Kooyman - One of the best experts on this subject based on the ideXlab platform.
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interactIon between enantiomers of mianserin and org3770 at 5 ht3 receptors in cultured mouse neuroblastoma cells
Neuropharmacology, 1994Co-Authors: Andre R Kooyman, Ruud Zwart, P M L Vanderheijden, J A Van Hooft, Henk P M VijverbergAbstract:Abstract Stereoselective effects of mianserin and ORG3770 on serotonin 5-HT3 receptors in mouse neuroblastoma N1E-115 cells have been investigated in radioligand binding and in whole-cell voltage clamp experiments. The specific binding of [3H]GR65630 to 5-HT3 recognitIon sites in N1E-115 cell homogenates is reduced by mianserin and ORG3770 and their enantiomers. The p Ki values of the more potent (R)enantiomers of mianserin and ORG3770 are 8.44 and 8.62, respectively. The (R)enantiomers of mianserin and ORG3770 are 15 and 37 times more potent than their respective(S)enantiomers. The racemates are only 1.9 and 3.3 times less potent than the corresponding (R)enantiomers. In voltage clamp experiments the (R)enantiomers block the 5-hydroxytryptamine(5-HT)-induced Ion Current with pIC50 values of 8.52 for (R)mianserin and 8.26 for the (R)enantiomer of ORG3770. The (R)enantiomers of mianserin and ORG3770 are 24 and 145 times more potent in blocking the 5-HT-induced Ion Current than their respective (S)enantiomers. The racemates are 6 and 13 times less potent than the corresponding (R)enantiomers. In additIon, the block of 5-HT-induced Ion Current by the (R)enantiomer of ORG3770 is partially reversed by a low concentratIon of its (S)enantiomer. The results indicate that the two enantiomers block the 5-HT3 receptor-mediated Ion Current in a mutually dependent manner.
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5 hydroxyindole slows desensitizatIon of the 5 ht3 receptor mediated Ion Current in n1e 115 neuroblastoma cells
British Journal of Pharmacology, 1993Co-Authors: Andre R Kooyman, Johannes A Van Hooft, Henk P M VijverbergAbstract:Abstract Effects of 5-hydroxyindole (5-OHi) on 5-HT3 receptor-operated Ion Current were investigated in voltage-clamped N1E-115 neuroblastoma cells. In the presence of 1 mM 5-OHi, the amplitudes of inward Currents induced by the agonists 5-hydroxytryptamine (5-HT), 2-methyl-5-HT and dopamine were enhanced and desensitizatIon of the responses was markedly slowed down. The results indicate that 5-OHi selectively modifies the desensitizatIon of the 5-HT3 receptor-mediated Ion Current.
Johannes A Van Hooft - One of the best experts on this subject based on the ideXlab platform.
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allosteric potentiatIon of the 5 ht3 receptor mediated Ion Current in n1e 115 neuroblastoma cells by 5 hydroxyindole and analogues
Neuropharmacology, 1997Co-Authors: Johannes A Van Hooft, E Van Der Haar, Henk P M VijverbergAbstract:Abstract PotentiatIon of the 5-HT3 receptor-mediated Ion Current in mouse N1E-115 neuroblastoma cells by 5-hydroxyindole (5-OHi) and three analogues (5-aminoindole, catechol and indole) was examined using whole-cell voltage clamp and single channel patch clamp techniques. The substances tested enhanced the amplitude of the maximum 5-HT-evoked Ion Current by 12–30%. The rank order (at 1 mM) to potentiate the 5-HT-induced Current was: 5-OHi ≈5-aminoindole≈catechol>indole. The concentratIon-effect curve of 5-HT was shifted leftwards by 1 mM 5-OHi, resulting in a two-fold increase of the apparent affinity of 5-HT from 1.4 μM to 0.7 μM, without affecting the Hill coefficient. The time constant of reversal of activatIon of the 5-HT-induced Ion Current upon washout of the agonist was delayed by 1 mM 5-OHi from 4.0 sec to 12.8 sec. 5-HT3 receptor-gated single channel events in cell-attached patches in the presence and absence of 1 mM 5-OHi were indistinguishable, apart from a slight increase in the event frequency. The results suggest that 5-OHi and analogues potentiate the 5-HT3 receptor-mediated Ion Current by delaying agonist dissociatIon and thereby increase the probability of channel opening. From the increased apparent affinity of 5-HT and the non-surmountability of the potentiating effect, it is concluded that 5-OHi and analogues are allosteric modulators of 5-HT3 receptors. © 1997 Elsevier Science Ltd.
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5 hydroxyindole slows desensitizatIon of the 5 ht3 receptor mediated Ion Current in n1e 115 neuroblastoma cells
British Journal of Pharmacology, 1993Co-Authors: Andre R Kooyman, Johannes A Van Hooft, Henk P M VijverbergAbstract:Abstract Effects of 5-hydroxyindole (5-OHi) on 5-HT3 receptor-operated Ion Current were investigated in voltage-clamped N1E-115 neuroblastoma cells. In the presence of 1 mM 5-OHi, the amplitudes of inward Currents induced by the agonists 5-hydroxytryptamine (5-HT), 2-methyl-5-HT and dopamine were enhanced and desensitizatIon of the responses was markedly slowed down. The results indicate that 5-OHi selectively modifies the desensitizatIon of the 5-HT3 receptor-mediated Ion Current.
