Academic literature on the topic 'Multi-ion channel'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Multi-ion channel.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Multi-ion channel"
1
Gao, Jianzhao, Hong Wei, Alberto Cano, and Lukasz Kurgan. "PSIONplusm Server for Accurate Multi-Label Prediction of Ion Channels and Their Types." Biomolecules 10, no. 6 (June 7, 2020): 876. http://dx.doi.org/10.3390/biom10060876.
Full textAbstract:
Computational prediction of ion channels facilitates the identification of putative ion channels from protein sequences. Several predictors of ion channels and their types were developed in the last quindecennial. While they offer reasonably accurate predictions, they also suffer a few shortcomings including lack of availability, parallel prediction mode, single-label prediction (inability to predict multiple channel subtypes), and incomplete scope (inability to predict subtypes of the voltage-gated channels). We developed a first-of-its-kind PSIONplusm method that performs sequential multi-label prediction of ion channels and their subtypes for both voltage-gated and ligand-gated channels. PSIONplusm sequentially combines the outputs produced by three support vector machine-based models from the PSIONplus predictor and is available as a webserver. Empirical tests show that PSIONplusm outperforms current methods for the multi-label prediction of the ion channel subtypes. This includes the existing single-label methods that are available to the users, a naïve multi-label predictor that combines results produced by multiple single-label methods, and methods that make predictions based on sequence alignment and domain annotations. We also found that the current methods (including PSIONplusm) fail to accurately predict a few of the least frequently occurring ion channel subtypes. Thus, new predictors should be developed when a larger quantity of annotated ion channels will be available to train predictive models.
2
Neyton, J., and M. Pelleschi. "Multi-ion occupancy alters gating in high-conductance, Ca(2+)-activated K+ channels." Journal of General Physiology 97, no. 4 (April 1, 1991): 641–65. http://dx.doi.org/10.1085/jgp.97.4.641.
Full textAbstract:
In this study, single-channel recordings of high-conductance Ca(2+)-activated K+ channels from rat skeletal muscle inserted into planar lipid bilayer were used to analyze the effects of two ionic blockers, Ba2+ and Na+, on the channel's gating reactions. The gating equilibrium of the Ba(2+)-blocked channel was investigated through the kinetics of the discrete blockade induced by Ba2+ ions. Gating properties of Na(+)-blocked channels could be directly characterized due to the very high rates of Na+ blocking/unblocking reactions. While in the presence of K+ (5 mM) in the external solution Ba2+ is known to stabilize the open state of the blocked channel (Miller, C., R. Latorre, and I. Reisin. 1987. J. Gen. Physiol. 90:427-449), we show that the divalent blocker stabilizes the closed-blocked state if permeant ions are removed from the external solution (K+ less than 10 microM). Ionic substitutions in the outer solution induce changes in the gating equilibrium of the Ba(2+)-blocked channel that are tightly correlated to the inhibition of Ba2+ dissociation by external monovalent cations. In permeant ion-free external solutions, blockade of the channel by internal Na+ induces a shift (around 15 mV) in the open probability--voltage curve toward more depolarized potentials, indicating that Na+ induces a stabilization of the closed-blocked state, as does Ba2+ under the same conditions. A kinetic analysis of the Na(+)-blocked channel indicates that the closed-blocked state is favored mainly by a decrease in opening rate. Addition of 1 mM external K+ completely inhibits the shift in the activation curve without affecting the Na(+)-induced reduction in the apparent single-channel amplitude. The results suggest that in the absence of external permeant ions internal blockers regulate the permeant ion occupancy of a site near the outer end of the channel. Occupancy of this site appears to modulate gating primarily by speeding the rate of channel opening.
3
Roux, Benoît, Toby Allen, Simon Bernèche, and Wonpil Im. "Theoretical and computational models of biological ion channels." Quarterly Reviews of Biophysics 37, no. 1 (February 2004): 15–103. http://dx.doi.org/10.1017/s0033583504003968.
Full textAbstract:
1. Introduction 172. Dynamics of many-body systems 192.1 Effective dynamics of reduced systems 212.2 The constraint of thermodynamic equilibrium 242.3 Mean-field theories 253. Solvation free energy and electrostatics 273.1 Microscopic view of the Born model 273.2 Ion–Ion interactions in bulk solution 293.3 Continuum electrostatics and the PB equation 293.4 Limitations of continuum dielectric models 323.5 The dielectric barrier 333.6 The transmembrane potential and the PB-V equation 354. Statistical mechanical equilibrium theory 404.1 Multi-ion PMF 404.2 Equilibrium probabilities of occupancy 434.3 Coupling to the membrane potential 444.4 Ionic selectivity 484.5 Reduction to a one-dimensional (1D) free-energy profile 495. From MD toI–V: a practical guide 505.1 Extracting the essential ingredients from MD 515.1.1 Channel conductance from equilibrium and non-equilibrium MD 515.1.2 PMF techniques 525.1.3 Friction and diffusion coefficient techniques 535.1.4 About computational times 555.2 Ion permeation models 565.2.1 The 1D-NP electrodiffusion theory 565.2.2 Discrete-state Markov chains 575.2.3 The GCMC/BD algorithm 585.2.4 PNP electrodiffusion theory 626. Computational studies of ion channels 636.1 Computational studies of gA 656.1.1 Free-energy surface for K+ permeation 666.1.2 Mean-force decomposition 696.1.3 Cation-binding sites 696.1.4 Channel conductance 706.1.5 Selectivity 726.2 Computational studies of KcsA 726.2.1 Multi-ion free-energy surface and cation-binding sites 736.2.2 Channel conductance 746.2.3 Mechanism of ion conduction 776.2.4 Selectivity 786.3 Computational studies of OmpF 796.3.1 The need to compare the different level of approximations 796.3.2 Equilibrium protein fluctuations and ion distribution 806.3.3 Non-equilibrium ion fluxes 806.3.4 Reversal potential and selectivity 846.4 Successes and limitations 876.4.1 Channel structure 876.4.2 Ion-binding sites 876.4.3 Ion conduction 886.4.4 Ion selectivity 897. Conclusion 908. Acknowledgments 939. References 93The goal of this review is to establish a broad and rigorous theoretical framework to describe ion permeation through biological channels. This framework is developed in the context of atomic models on the basis of the statistical mechanical projection-operator formalism of Mori and Zwanzig. The review is divided into two main parts. The first part introduces the fundamental concepts needed to construct a hierarchy of dynamical models at different level of approximation. In particular, the potential of mean force (PMF) as a configuration-dependent free energy is introduced, and its significance concerning equilibrium and non-equilibrium phenomena is discussed. In addition, fundamental aspects of membrane electrostatics, with a particular emphasis on the influence of the transmembrane potential, as well as important computational techniques for extracting essential information from all-atom molecular dynamics (MD) simulations are described and discussed. The first part of the review provides a theoretical formalism to ‘translate’ the information from the atomic structure into the familiar language of phenomenological models of ion permeation. The second part is aimed at reviewing and contrasting results obtained in recent computational studies of three very different channels; the gramicidin A (gA) channel, which is a narrow one-ion pore (at moderate concentration), the KcsA channel from Streptomyces lividans, which is a narrow multi-ion pore, and the outer membrane matrix porin F (OmpF) from Escherichia coli, which is a trimer of three β-barrel subunits each forming wide aqueous multi-ion pores. Comparison with experiments demonstrates that current computational models are approaching semi-quantitative accuracy and are able to provide significant insight into the microscopic mechanisms of ion conduction and selectivity. We conclude that all-atom MD with explicit water molecules can represent important structural features of complex biological channels accurately, including such features as the location of ion-binding sites along the permeation pathway. We finally discuss the broader issue of the validity of ion permeation models and an outlook to the future.
4
Hill, J. A., R. Coronado, and H. C. Strauss. "Potassium channel of cardiac sarcoplasmic reticulum is a multi-ion channel." Biophysical Journal 55, no. 1 (January 1989): 35–45. http://dx.doi.org/10.1016/s0006-3495(89)82778-x.
Full text
5
Yue, D. T., and E. Marban. "Permeation in the dihydropyridine-sensitive calcium channel. Multi-ion occupancy but no anomalous mole-fraction effect between Ba2+ and Ca2+." Journal of General Physiology 95, no. 5 (May 1, 1990): 911–39. http://dx.doi.org/10.1085/jgp.95.5.911.
Full textAbstract:
We investigated the mechanism whereby ions cross dihydropyridine-sensitive (L-type) Ca channels in guinea pig ventricular myocytes. At the single-channel level, we found no evidence of an anomalous mole-fraction effect like that reported previously for whole-cell currents in mixtures of Ba and Ca. With the total concentration of Ba + Ca kept constant at 10 (or 110) mM, neither conductance nor absolute unitary current exhibits a paradoxical decrease when Ba and Ca are mixed, thereby weakening the evidence for a multi-ion permeation scheme. We therefore sought independent evidence to support or reject the multi-ion nature of the L-type Ca channel by measuring conductance at various permeant ion concentrations. Contrary to the predictions of models with only one binding site in the permeation pathway, single-channel conductance does not follow Michaelis-Menten kinetics as Ba activity is increased over three orders of magnitude. Two-fold variation in the Debye length of permeant ion solutions has little effect on conductance, making it unlikely that local surface charge effects could account for these results. Instead, the marked deviation from Michaelis-Menten behavior was best explained by supposing that the permeation pathway contains three or more binding sites that can be occupied simultaneously. The presence of three sites helps explain both a continued rise in conductance as [Ba2+] is increased above 110 mM, and the high single-channel conductance (approximately 7 pS) with 1 mM [Ba2+] as the charge carrier; the latter feature enables the L-type channel to carry surprisingly large currents at physiological divalent cation concentrations. Thus, despite the absence of an anomalous mole-fraction effect between Ba and Ca, we suggest that the L-type Ca channel in heart cells supports ion flux by a single-file, multi-ion permeation mechanism.
6
García-Giménez, Elena, Antonio Alcaraz, and Vicente M. Aguilella. "Divalent Metal Ion Transport across Large Biological Ion Channels and Their Effect on Conductance and Selectivity." Biochemistry Research International 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/245786.
Full textAbstract:
Electrophysiological characterization of large protein channels, usually displaying multi-ionic transport and weak ion selectivity, is commonly performed at physiological conditions (moderate gradients of KCl solutions at decimolar concentrations buffered at neutral pH). We extend here the characterization of the OmpF porin, a wide channel of the outer membrane ofE. coli,by studying the effect of salts of divalent cations on the transport properties of the channel. The regulation of divalent cations concentration is essential in cell metabolism and understanding their effects is of key importance, not only in the channels specifically designed to control their passage but also in other multiionic channels. In particular, in porin channels like OmpF, divalent cations modulate the efficiency of molecules having antimicrobial activity. Taking advantage of the fact that the OmpF channel atomic structure has been resolved both in water and in MgCl2aqueous solutions, we analyze the single channel conductance and the channel selectivity inversion aiming to separate the role of the electrolyte itself, and the counterion accumulation induced by the protein channel charges and other factors (binding, steric effects, etc.) that being of minor importance in salts of monovalent cations become crucial in the case of divalent cations.
7
Linsdell, Paul, Joseph A. Tabcharani, and John W. Hanrahan. "Multi-Ion Mechanism for Ion Permeation and Block in the Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel." Journal of General Physiology 110, no. 4 (October 1, 1997): 365–77. http://dx.doi.org/10.1085/jgp.110.4.365.
Full textAbstract:
The mechanism of Cl− ion permeation through single cystic fibrosis transmembrane conductance regulator (CFTR) channels was studied using the channel-blocking ion gluconate. High concentrations of intracellular gluconate ions cause a rapid, voltage-dependent block of CFTR Cl− channels by binding to a site ∼40% of the way through the transmembrane electric field. The affinity of gluconate block was influenced by both intracellular and extracellular Cl− concentration. Increasing extracellular Cl− concentration reduced intracellular gluconate affinity, suggesting that a repulsive interaction occurs between Cl− and gluconate ions within the channel pore, an effect that would require the pore to be capable of holding more than one ion simultaneously. This effect of extracellular Cl− is not shared by extracellular gluconate ions, suggesting that gluconate is unable to enter the pore from the outside. Increasing the intracellular Cl− concentration also reduced the affinity of intracellular gluconate block, consistent with competition between intracellular Cl− and gluconate ions for a common binding site in the pore. Based on this evidence that CFTR is a multi-ion pore, we have analyzed Cl− permeation and gluconate block using discrete-state models with multiple occupancy. Both two- and three-site models were able to reproduce all of the experimental data with similar accuracy, including the dependence of blocker affinity on external Cl− (but not gluconate) ions and the dependence of channel conductance on Cl− concentration. The three-site model was also able to predict block by internal and external thiocyanate (SCN−) ions and anomalous mole fraction behavior seen in Cl−/SCN− mixtures.
8
Yu, Shijin, Wenzhen Zhu, Ying Wei, Jiahao Tong, Quanya Wei, Tianrui Chen, Xuannan He, Dingwen Hu, Cuiyun Li, and Hua Zhu. "Facile Synthesis of Multi-Channel Surface-Modified Amorphous Iron Oxide Nanospheres as High-Performance Anode Materials for Lithium-Ion Batteries." Energies 15, no. 16 (August 18, 2022): 5974. http://dx.doi.org/10.3390/en15165974.
Full textAbstract:
Based on the synergistic effect of ripening and hydrogen ion etching in a hydrothermal solution, a simple, facile, and low-cost new strategy was demonstrated to prepare multi-channel surface-modified amorphous Fe2O3 nanospheres as anodes for Li-ion batteries in this study. Compared with polycrystalline Fe2O3, the conversion reaction between amorphous Fe2O3 and lithium ions has a lower Gibbs free energy change and a stronger reversibility, which can contribute to an elevation in the cycle capability of the electrode. Meanwhile, there are abundant active sites and more effective dangling bonds/defects in amorphous materials, which is beneficial to promote charge transfer and lithium-ion migration kinetics. The Galvanostatic intermittent titration analysis results confirmed that the amorphous Fe2O3 electrode had a higher Li+ diffusion coefficient. In addition, the surfaces of the amorphous nanospheres are corroded to produce multiple criss-cross channels. The multi-channel surface structure can not only increase the contact area between Fe2O3 nanospheres and electrolyte, but also reserve space for volume expansion, thereby effectively alleviating the volume change during the intercalation-deintercalation of lithium ions. The electrochemical performance showed that the multi-channel surface-modified amorphous Fe2O3 electrode exhibited a higher specific capacity, a more stable cycle performance, and a narrower voltage hysteresis. It is believed that amorphous metal oxides have great potential as high-performance anodes of next-generation lithium-ion batteries.
9
Hu, Gui Hua, Jun Ming Xu, Ji Jun Zhou, and Xiaoping Hu. "Design of Li-Ion Battery Management System Based on Atmega16." Applied Mechanics and Materials 263-266 (December 2012): 335–38. http://dx.doi.org/10.4028/www.scientific.net/amm.263-266.335.
Full textAbstract:
Due to the negative effect of li-ion battery monomer inconsistent performance in electric bicycle, a low-cost intelligent li-ion BMS (battery management system) is designed based on atmega16. Multi-channel analog switch and differential amplifier are used for multi-channel data acquisition, and the equalization circuit is used for the balance of each single cell. The results show that the design can realize the intelligent management of li-ion battery.
10
Kuo, Chung-Chin, Wan-Yu Chen, and Ya-Chin Yang. "Block of Tetrodotoxin-resistant Na+ Channel Pore by Multivalent Cations." Journal of General Physiology 124, no. 1 (June 28, 2004): 27–42. http://dx.doi.org/10.1085/jgp.200409054.
Full textAbstract:
Tetrodotoxin-resistant (TTX-R) Na+ channels are much less susceptible to external TTX but more susceptible to external Cd2+ block than tetrodotoxin-sensitive (TTX-S) Na+ channels. Both TTX and Cd2+ seem to block the channel near the “DEKA” ring, which is probably part of a multi-ion single-file region adjacent to the external pore mouth and is involved in the selectivity filter of the channel. In this study we demonstrate that other multivalent transitional metal ions such as La3+, Zn2+, Ni2+, Co2+, and Mn2+ also block the TTX-R channels in dorsal root ganglion neurons. Just like Cd2+, the blocking effect has little intrinsic voltage dependence, but is profoundly influenced by Na+ flow. The apparent dissociation constants of the blocking ions are always significantly smaller in inward Na+ currents than those in outward Na+ current, signaling exit of the blocker along with the Na+ flow and a high internal energy barrier for “permeation” of these multivalent blocking ions through the pore. Most interestingly, the activation and especially the inactivation kinetics are slowed by the blocking ions. Moreover, the gating changes induced by the same concentration of a blocking ion are evidently different in different directions of Na+ current flow, but can always be correlated with the extent of pore block. Further quantitative analyses indicate that the apparent slowing of channel activation is chiefly ascribable to Na+ flow–dependent unblocking of the bound La3+ from the open Na+ channel, whereas channel inactivation cannot happen with any discernible speed in the La3+-blocked channel. Thus, the selectivity filter of Na+ channel is probably contiguous to a single-file multi-ion region at the external pore mouth, a region itself being nonselective in terms of significant binding of different multivalent cations. This region is “open” to the external solution even if the channel is “closed” (“deactivated”), but undergoes imperative conformational changes during the gating (especially the inactivation) process of the channel.
Dissertations / Theses on the topic "Multi-ion channel"
1
Hoyles, Matthew, and Matthew Hoyles@anu edu au. "Computer Simulation of Biological Ion Channels." The Australian National University. Theoretical Physics, 2000. http://thesis.anu.edu.au./public/adt-ANU20010702.135814.
Full textAbstract:
This thesis describes a project in which algorithms are developed for the rapid and accurate solution of Poisson's equation in the presence of a dielectric boundary and multiple point charges. These algorithms are then used to perform Brownian dynamics simulations on realistic models of biological ion channels. An iterative method of solution, in which the dielectric boundary is tiled with variable sized surface charge sectors, provides the flexibility to deal with arbitrarily shaped boundaries, but is too slow to perform Brownian dynamics. An analytical solution is derived, which is faster and more accurate, but only works for a toroidal boundary. Finally, a method is developed of pre-calculating solutions to Poisson's equation and storing them in tables. The solution for a particular configuration of ions in the channel can then be assembled by interpolation from the tables and application of the principle of superposition. This algorithm combines the flexibility of the iterative method with greater speed even than the analytical method, and is fast enough that channel conductance can be predicted. The results of simulations for a model single-ion channel, based on the acetylcholine receptor channel, show that the narrow pore through the low dielectric strength medium of the protein creates an energy barrier which restricts the permeation of ions. They further show that this barrier can be removed by dipoles in the neck of the channel, but that the barrier is not removed by shielding by counter-ions. The results of simulations for a model multi-ion channel, based on a bacterial potassium channel, show that the model channel has conductance characteristics similar to those of real potassium channels. Ions appear to move through the model multi-ion channel via rapid transitions between a series of semi-stable states. This observation suggests a possible physical basis for the reaction rate theory of channel conductance, and opens up an avenue for future research.
2
Hsu, Chun-Cheng M. Eng Massachusetts Institute of Technology. "Investigation of ion transfer efficiency through multi-channel capillaries for a Desorption Electrospray Ionization (DESI) interface." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/130722.
Full textAbstract:
Thesis: M. Eng. in Advanced Manufacturing and Design, Massachusetts Institute of Technology, Department of Mechanical Engineering, February, 2021Cataloged from the official PDF of thesis. "February 2021."
Includes bibliographical references (page 53).
Desorption Electrospray Ionization (DESI) coupled with mass spectrometry (MS) is an efficient imaging technique for obtaining the spatial distribution of molecular species from a surface. In this study, we experimented with different capillary geometries to maximize the signal intensity of analyte peaks obtained through DESI by improving the temperature uniformity throughout the capillary flow. Multi-channel capillaries were discovered to be more sensitive to temperature and less prone to turbulence under certain conditions when compared to single channel capillaries. A multiple regression analysis reveals the significance of the surface-area-to-volume ratio, inlet-to-outlet area ratio, and the interaction of these main effects with temperature. This study illustrates the complex tradeoff between desolvation and ion loss, thereby providing a general guideline to instrumentation design for the purpose of maximizing signal intensity of the MS.
by Chun-Cheng, Hsu.
M. Eng. in Advanced Manufacturing and Design
M.Eng.inAdvancedManufacturingandDesign Massachusetts Institute of Technology, Department of Mechanical Engineering
3
Wang, Ling. "Microchannel enhanced neuron-computer interface: design, fabrication, biophysics of signal generation, signal strength optimization, and its applications to ion-channel screening and basic neuroscience research." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/52810.
Full textAbstract:
En el presente trabajo, utilizamos técnicas de microfabricación, simulaciones
numéricas, experimentos de electrofisiología para explorar la viabilidad en me-
jorar la interface ordenador-neurona a través de microcanales, y la biofísica para
la generación de señales en los dispositivos con microcanales. También demos-
tramos que los microcanales pueden ser usados como una técnica prometedora
con alto rendimiento en el muestreo automático de canales iónicos a nivel subce-
lular. Finalmente, se ha diseñado, fabricado y probado el micropozo-microcanal
como modificación adicional a los arreglos de multielectrodos, permitiendo una
alta ganancia en la relación señal/ ruido (en inglés Signal to Noise Ratio SNR),
y el registro de múltiples-lugares en poblaciones de baja densidad de redes neu-
ronales del hipocampo in vitro.
Primero, demostramos que son de alto rendimiento los microcanales de bajo
costo con interface neurona-electrodo, para el registro extracelular de la activi-
dad neuronal con baja complexidad, por periodos estables de larga duración y
con alta ganancia SNR.
En seguida, se realiza un estudio mediante experimentos y simulaciones nu-
méricas de la biofísica para la generación de las señales obtenidas de los dispositi-
vos con microcanales. Basados en los resultados, racionalizamos y demostramos
como es que la longitud del canal (siendo 200 μm) y la sección transversal del
microcanal (siendo 12 μm2) canaliza a los potenciales de acción para estar
dentro del rango de milivolts. A pesar del bajo grado de complexidad envuelto
en la fabricación y aplicación, los dispositivos con microcanales otorgan una sola
media de valor SNR de 101 76, lo cual es favorablemente comparable con la
SNR que se obtiene de desarrollos recientes que emplean electrodos curados con
CNT y Si-NWFETs.
Más aún, nosotros demostramos que el microcanal es una técnica promete-
dora para el alto rendimiento del muestro automático de canales iónicos a nivel
subcelular: (1) Información experimental y simulaciones numéricas sugieren que
las señales registradas sólo afectan los parches membranales localizados dentro
del microcanal o alrededor de 100 μm de las entradas del microcanal. (2) La
transferencia de masa de los componentes químicos en los microcanales fue ana-
lizada por experimentos y simulaciones FEM. Los resultados muestran que los
microcanales que contienen glía y tejido neuronal pueden funcionar como barre-
ra de fluido/química. Los componentes químicos pueden ser solamente aplicados
a diferentes compartimentos a nivel subcelular.
Finalmente, basado en simulaciones numéricas y resultados experimentales,
se propone que del micropozo-microcanal, obtenido de la modificación de MEA
(MWMC-MEA), la longitud óptima del canal debe ser 0,3 mm y la posición
1
óptima del electrodo intracanal, hacia la entrada más cercana del microcanal,
debe ser 0,1 mm. Nosotros fabricamos un prototipo de MWMC-MEA, cuyo hoyo
pasante sobre las películas de Polydimethylsiloxane (PDMS) fue microtrabajado
a través de la técnica de grabados reactivos de plasma de iones. La baja densidad
del cultivo (57 neuronas /mm2) en el MWMC-MEAs permitió que las neuronas
vivieran al menos 14 días, con lo que la señal neuronal con la máxima SNR
obtenida fue de 142.
2In this present work, we used microfabrication techniques, numerical simulations, electrophysiological experiments to explore the feasibility of enhancing neuron-computer interfaces with microchannels and the biophysics of the signal generation in microchannel devices. We also demonstrate the microchannel can be used as a promising technique for high-throughput automatic ion-channel screening at subcellular level. Finally, a microwell-microchannel enhanced multielectrode array allowing high signal-to-noise ratio (SNR), multi-site recording from the low-density hippocampal neural network in vitro was designed, fabricated and tested. First, we demonstrate using microchannels as a low-cost neuron-electrode interface to support low-complexity, long-term-stable, high SNR extracellular recording of neural activity, with high-throughput potential. Next, the biophysics of the signal generation of microchannel devices was studied by experiments and numerical simulations. Based on the results, we demonstrate and rationalize how channels with a length of 200 μm and channel cross section of 12 μm2 yielded spike sizes in the millivolt range. Despite the low degree of complexity involved in their fabrication and use, microchannel devices provided a single-unit mean SNR of 101 76, which compares favourably with the SNR obtained from recent developments employing CNT-coated electrodes and Si-NWFETs. Moreover, we further demonstrate that the microchannel is a promising technique for high-throughput automatic ion-channel screening at subcellular level: (1) Experimental data and numerical simulations suggest that the recorded signals are only affected by the membrane patches located inside the microchannel or within 100 μm to the microchannel entrances. (2) The mass transfer of chemical compounds in microchannels was analyzed by experiments and FEM simulations. The results show that the microchannel threaded by glial and neural tissue can function as fluid/chemical barrier. Thus chemical compounds can be applied to different subcellular compartments exclusively. Finally, a microwell-microchannel enhanced MEA (MWMC-MEA), with the optimal channel length of 0.3 mm and the optimal intrachannel electrode position of 0.1 mm to the nearest channel entrance, was proposed based on numerical simulation and experiment results. We fabricated a prototype of the MWMCMEA, whose through-hole feature of Polydimethylsiloxane film (PDMS) was micromachined by reactive-ion etching. The low-density culture (57 neurons/mm2) were survived on the MWMC-MEAs for at least 14 days, from which the neuronal signal with the maximum SNR of 142 was obtained.
4
Gwan, Jean-Fang. "The molecular mechanism of multi-ion conduction in K+ channels." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=983151253.
Full text
5
Zhao, Jun. "Multi-scale Molecular Dynamics Simulations of Membrane-associated Peptides." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1377265339.
Full text
6
Hoyles, Matthew. "Computer Simulation of Biological Ion Channels." Phd thesis, 1999. http://hdl.handle.net/1885/47286.
Full textAbstract:
This thesis describes a project in which algorithms are developed for the rapid and accurate solution of Poisson's equation in the presence of a dielectric boundary and multiple point charges. These algorithms are then used to perform Brownian dynamics simulations on realistic models of biological ion channels. An iterative method of solution, in which the dielectric boundary is tiled with variable sized surface charge sectors, provides the flexibility to deal with arbitrarily shaped boundaries, but is too slow to perform Brownian dynamics. An analytical solution is derived, which is faster and more accurate, but only works for a toroidal boundary. Finally, a method is developed of pre-calculating solutions to Poisson's equation and storing them in tables. The solution for a particular configuration of ions in the channel can then be assembled by interpolation from the tables and application of the principle of superposition. This algorithm combines the flexibility of the iterative method with greater speed even than the analytical method, and is fast enough that channel conductance can be predicted. The results of simulations for a model single-ion channel, based on the acetylcholine receptor channel, show that the narrow pore through the low dielectric strength medium of the protein creates an energy barrier which restricts the permeation of ions. They further show that this barrier can be removed by dipoles in the neck of the channel, but that the barrier is not removed by shielding by counter-ions. The results of simulations for a model multi-ion channel, based on a bacterial potassium channel, show that the model channel has conductance characteristics similar to those of real potassium channels. Ions appear to move through the model multi-ion channel via rapid transitions between a series of semi-stable states. This observation suggests a possible physical basis for the reaction rate theory of channel conductance, and opens up an avenue for future research.
7
Antony, Joseph. "Performance Models for Electronic Structure Methods on Modern Computer Architectures." Phd thesis, 2009. http://hdl.handle.net/1885/49420.
Full textAbstract:
Electronic structure codes are computationally intensive scientic applications used to probe and elucidate chemical processes at an atomic level. Maximizing the performance of these applications on any given hardware platform is vital in order to facilitate larger and more accurate computations. An important part of this endeavor is the development of protocols for measuring performance, and models to describe that performance as a function of system architecture. This thesis makes contributions in both areas, with a focus on shared memory parallel computer architectures and the Gaussian electronic structure code. Shared memory parallel computer systems are increasingly important as hardware man- ufacturers are unable to extract performance improvements by increasing clock frequencies. Instead the emphasis is on using multi-core processors to provide higher performance. These processor chips generally have complex cache hierarchies, and may be coupled together in multi-socket systems which exhibit highly non-uniform memory access (NUMA) characteristics. This work seeks to understand how cache characteristics and memory/thread placement affects the performance of electronic structure codes, and to develop performance models that can be used to describe and predict code performance by accounting for these effects. A protocol for performing memory and thread placement experiments on NUMA systems is presented and its implementation under both the Solaris and Linux operating systems is discussed. A placement distribution model is proposed and subsequently used to guide both memory/thread placement experiments and as an aid in the analysis of results obtained from experiments. In order to describe single threaded performance as a function of cache blocking a simple linear performance model is investigated for use when computing the electron repulsion integrals that lie at the heart of virtually all electronic structure methods. A parametric cache variation study is performed. This is achieved by combining parameters obtained for the linear performance model on existing hardware, with instruction and cache miss counts obtained by simulation, and predictions are made of performance as a function of cache architecture. Extension of the linear performance model to describe multi-threaded performance on complex NUMA architectures is discussed and investigated experimentally. Use of dynamic page migration to improve locality is also considered. Finally the use of large scale electronic structure calculations is demonstrated in a series of calculations aiming to study the charge distribution for a single positive ion solvated within a shell of water molecules of increasing size.
8
Gwan, Jean-Fang [Verfasser]. "The molecular mechanism of multi-ion conduction in K+ channels / von Jean-Fang Gwan." 2007. http://d-nb.info/983151253/34.
Full text
9
Lewis, Shanta. "Effects of carbon nanotubes on barrier epithelial cells via effects on lipid bilayers." Thesis, 2013. http://hdl.handle.net/1805/5611.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)Carbon nanotubes (CNTs) are one of the most common nanoparticles (NP) found in workplace air. Therefore, there is a strong chance that these NP will enter the human body. They have similar physical properties to asbestos, a known toxic material, yet there is limited evidence showing that CNTs may be hazardous to human barrier epithelia. In previous studies done in our laboratory, the effects of CNTs on the barrier function in the human airway epithelial cell line (Calu-3) were measured. Measurements were done using electrophysiology, a technique which measures both transepithelial electrical resistance (TEER), a measure of monolayer integrity, and short circuit current (SCC) which is a measure of vectorial ion transport across the cell monolayer. The research findings showed that select physiologically relevant concentrations of long single-wall (SW) and multi-wall (MW) CNTs significantly decreased the stimulated SCC of the Calu-3 cells compared to untreated cultures. Calu-3 cells showed decreases in TEER when incubated for 48 hours (h) with concentrations of MWCNT ranging from 4µg/cm2 to 0.4ng/cm2 and SWCNT ranging from 4µg/cm2 to 0.04ng/cm2. The impaired cellular function, despite sustained cell viability, led us to investigate the mechanism by which the CNTs were affecting the cell membrane. We investigated the interaction of short MWCNTs with model lipid membranes using an ion channel amplifier, Planar Bilayer Workstation. Membranes were synthesized using neutral diphytanoylphosphatidylcholine (DPhPC) and negatively charged diphytanoylphosphatidylserine (DPhPS) lipids. Gramicidin A (GA), an ion channel reporter protein, was used to measure changes in ion channel conductance due to CNT exposures. Synthetic membranes exposed to CNTs allowed bursts of currents to cross the membrane when they were added to the membrane buffer system. When added to the membrane in the presence of GA, they distorted channel formation and reduced membrane stability.
Books on the topic "Multi-ion channel"
1
Swayne, Leigh Anne, Christophe Altier, and Gerald W. Zamponi, eds. The truth in complexes: why unraveling ion channel multi-protein signaling nexuses is critical for understanding the function of the nervous system. Frontiers Media SA, 2015. http://dx.doi.org/10.3389/978-2-88919-445-2.
Full textBook chapters on the topic "Multi-ion channel"
1
Liu, Lu-xiang, Yong-dun Xie, Hui-jun Guo, Lin-shu Zhao, Hong-chun Xiong, Jia-yu Gu, and Shi-rong Zhao. "New mutation techniques for crop improvement in China." In Mutation breeding, genetic diversity and crop adaptation to climate change, 47–52. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0005.
Full textAbstract:
Abstract There are at least 1 billion hungry people worldwide and the Asia and Pacific region harbours the biggest estimated regional distribution of hunger. Lifting a billion people out of poverty and feeding more than 9 billion by 2050 will require increasing cereal production by 70%. Accelerating the development of agriculture to continually increase productivity should be the final approach to end poverty. Mutation techniques have played very significant roles in ensuring food security by developing new mutant germplasm and mutant varieties in China, which have generated a tremendous socio-economic impact. New mutagenesis approaches were initiated in the late 1980s by Chinese scientists, including spaceflight and heavy-ion beam irradiation used as new effective and alternative ways for crop genetic improvement. Protocols for crop mutation induction by space radiation with high-energy heavy-ion beams have been established and applied for crop breeding. More than 1030 mutant varieties with high-yielding, fine-quality and multi-resistant traits have been developed and officially released mainly in cereals, oil and vegetable crops. They have been playing an important role in agricultural production. Hundreds of rare mutant germplasm accessions with a possible breakthrough effect on main economic traits such as grain yield and quality were also identified and applied in conventional breeding programmes. The development of new mutation techniques will be heavily based on, and associated with, not only effective use of nuclear and aerospace research platforms, but also advanced plant omics and molecular biology.
2
Munteanu, Daniela, Jean-Luc Autran, and Sbastien Martinie. "Numerical Simulation of Transient Response in 3-D Multi-Channel Nanowire MOSFETs Submitted to Heavy Ion Irradiation." In Nanowires - Implementations and Applications. InTech, 2011. http://dx.doi.org/10.5772/16827.
Full text
3
Aizawa, Tatsuhiko, Tomomi Shiratori, Tomoaki Yoshino, Yohei Suzuki, and Takafumi Komatsu. "Nitrogen Supersaturation of AISI316 Base Stainless Steels at 673 K and 623 K for Hardening and Microstructure Control." In Stainless Steels [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102387.
Full textAbstract:
The high-density plasma nitriding at 673 K and 623 K was employed to make 10% of nitrogen supersaturation on AISI316 base austenitic stainless steels. The processing parameters and nitrogen-hydrogen gas flow ratio were optimized to increase the yield of N2+ ion and NH-radical for efficient nitriding. The nitrided AISI316 specimens were prepared for multidimensional analysis to describe the fundamental features of low-temperature plasma nitriding. First, macroscopic evaluation revealed that nitrogen supersaturation induced the γ-lattice expansion and the higher nitrogen content than 4% of mass in depth. The mesoscopic analysis describes the holding temperature and initial grain-size effects on the microstructure changes. Plastic straining, grain-size refinement, and nitrogen zone-boundary diffusion processes advance with nitrogen supersaturation to drive the inner nitriding behavior. The microscopic analysis explains the microstructure refinement, the two-phase structuring, and the microstructure modification. Through this multi-dimensional analysis, the essential characteristics of the low-temperature plasma nitriding of 316 austenitic stainless steels were precisely understood to extend the engineering treatise on the bulk nitrogen stainless steels for surface modification and treatment of stainless steels by nitriding. This plasma nitriding was applied to strengthen and harden the AISI316 wire surfaces toward its application on surgery wires.
Conference papers on the topic "Multi-ion channel"
1
Yu, Fan, Liqiang Zhang, Pengfei Lu, and Ming Li. "Design of Multi-channel EIS Measurement System for Lithium-ion Batteries." In 2020 11th International Conference on Prognostics and System Health Management (PHM-2020 Jinan). IEEE, 2020. http://dx.doi.org/10.1109/phm-jinan48558.2020.00039.
Full text
2
Ebersbach, Peter, Adam M. Urbanowicz, Dmitry Likhachev, and Carsten Hartig. "Monitoring of ion implantation in microelectronics production environment using multi-channel reflectometry." In SPIE Advanced Lithography, edited by Martha I. Sanchez and Vladimir A. Ukraintsev. SPIE, 2016. http://dx.doi.org/10.1117/12.2220184.
Full text
3
Engel, G. L., V. Vangapally, N. Duggireddi, L. G. Sobotka, J. M. Elson, R. J. Charity, Floyd D. McDaniel, and Barney L. Doyle. "Multi-Channel Integrated Circuits For Use In Research With Radioactive Ion Beams." In APPLICATION OF ACCELERATORS IN RESEARCH AND INDUSTRY: Twenty-First International Conference. AIP, 2011. http://dx.doi.org/10.1063/1.3586175.
Full text
4
Linan Zhang, Miao Zhang, and Mingya Sheng. "Development of a Multi-Channel Soil Macronutrient Detection System Using Ion-Selective Electrode." In 2012 Dallas, Texas, July 29 - August 1, 2012. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2012. http://dx.doi.org/10.13031/2013.42116.
Full text
5
Sidorov, V. P., S. Yu Udovichenko, N. G. Vaganov, and L. P. Skripal. "Formation of D− (H−) ion beams in a multi-channel ratio-frequency injector for ITER." In Production and neutralization of negative ions and beams. AIP, 1992. http://dx.doi.org/10.1063/1.44801.
Full text
6
Qin, Z. P., Y. S. Wang, and G. X. Wang. "Flow of Electrolyte With a Surface-Charged Particle in a Nano-Channel: Quasi-Steady Modeling." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12173.
Full textAbstract:
A Resistive Pulse Sensor (RPS) is a device for counting and characterizing small particles by recording the electrical current change (negative pulse) during the translocation of the particle through a small pore. RPS is now widely used to characterize various micro/nano size particles, including bio-particles, proteins, and DNA. This paper presents a comprehensive multi-physical model of RPS. The model involves a coupled system of the Navier-Stokes equation for flow field, the Nernst-Planck equation for electrolyte ion concentrations, and the Poisson equation for electrical field. The model is used to simulate the quasi-steady flow of electrolyte with a fixed surface charged particle in a micro/nano-channel connecting two reservoirs. The channel and reservoir are assumed to be cylindrical and a 2-D axial-symmetry system is used. The model predicts the flow and electric fields as well as the distribution of the ion concentrations in the channel. The effects of Electrical Double Layer (EDL) on the electric current change through the channel are then investigated. Conditions for the electric current change (positive and negative pulses) are then identified.
7
Ikeda, Keiji, Yuuichi Kamimuta, Noriyuki Taoka, Yoshihiko Moriyama, Minoru Oda, and Tsutomu Tezuka. "Precise thickness control of NiSi by nitrogen ion-implantation for multi-gate strained Si channel metal S/D MOSFETs." In 2010 Silicon Nanoelectronics Workshop (SNW). IEEE, 2010. http://dx.doi.org/10.1109/snw.2010.5562593.
Full text
8
Munteanu, Daniela, and Jean-Luc Autran. "Transient response of 3-D Multi-Channel nanowire MOSFETs submitted to heavy ion irradiation: A 3-D simulation study." In 2008 European Conference on Radiation and Its Effects on Components and Systems (RADECS). IEEE, 2008. http://dx.doi.org/10.1109/radecs.2008.5782711.
Full text
9
Kamakura, Y., G. Mil'nikov, N. Mori, and K. Taniguchi. "Impact of Attractive Ion in Undoped Channel on the Characteristics of Nanoscale Multi-Gate FETs: A 3D NEGF Study." In 2009 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2009. http://dx.doi.org/10.7567/ssdm.2009.c-7-4.
Full text
10
Goh, W. Z., B. Fong, H. Hussin, and S. F. Wan Muhamad Hatta. "Study of Scaling Limits of Multi-Gate Fets (Finfet) With High-K Dielectric." In International Technical Postgraduate Conference 2022. AIJR Publisher, 2022. http://dx.doi.org/10.21467/proceedings.141.18.
Full textAbstract:
Scaling of Multi-Gate FETs (FinFETs) to sub nanometer has seen several challenging problems such as short channel effects which significantly affect the device performance and huge off-state power leakage. High-k dielectric materials had always been looked at as a potential replacement to the conventional SiO2 to increase gate control over the channel which could be a possible solution. This paper examines the impact of scaling FinFETs with varying geometric conditions in the presence of high-k gate dielectrics oxide layer, and further demonstrate conflicting technical trade-off that emerges from short channel effects due to different oxide materials. The electric field distribution, carrier density and mobility of the FinFETs subsequent to miniaturization were also studied. A 3D model of the device is created and simulated using TiberLab and Nanohub to observe the carrier density and mobility in the device as well as the electric field created within the device. Short channel effects specifically drain induced barrier lowering (DIBL) and gate induced drain lowering (GIBL) were also analyzed. The overall results show that although high-k dielectric gate oxide has some drawbacks, it still outperforms SiO2 overall as a gate oxide material and proven to be a solid solution to mitigate short channel effect. The Ion/Ioff for the HfO2-based device increases by 90% as compared to a SiO2-based device. However, it was evident that the threshold voltage had increase slightly from 0.13 V to 0.26 V when the dielectric was changed from SiO2 to HfO2.