The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
Gou-jen Wang - One of the best experts on this subject based on the ideXlab platform.
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Measurement and control of the ion diffusion coefficient in a nanochannel
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, 2013Co-Authors: Yu-tze Tsai, Kang J. Chang, Gou-jen WangAbstract:In this study, we first propose a simple yet novel method to measure the diffusion coefficient of ions through a nanochannel. Back-side track etching is used for the fabrication of a nanochannel on an n-type silicon substrate. A metal-oxide semiconductor field-effect transistor (MOSFET) like device named the metal–semiconductor-solution field-effect transistor (MSSFET) is implemented to control the ion diffusion current. When a negative gate voltage is applied, positive ions that travel along the nanochannel are confined to the central zone of the nanochannel allowing the radial Brownian Movements to be reduced. The effect is equivalent to an increase of the diffusion coefficient. However, a positive gate voltage can produce an opposite Zeta potential on the nanochannel surface. The cations in the nanochannel are dragged to the channel surface. This condition can be regarded as a decrease of the diffusion coefficient. Experimental results illustrate that the transfer characteristics of the MSSFET are similar to those of a p-channel depletion-type MOSFET. The ion diffusion coefficient in a nanochannel can be controlled when the initial ion concentration difference across a nanochannel is larger than a certain threshold.
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Control of the ion diffusion coefficient in a nanochannel
2012 Symposium on Design Test Integration and Packaging of MEMS MOEMS, 2012Co-Authors: Yu-tze Tsai, Gou-jen WangAbstract:In this study, we first propose a simple yet novel method to measure the diffusion coefficient of ions through a nanochannel. Back-side track etching is used for the fabrication of a nanochannel on an n-type silicon substrate. A metal-oxide semiconductor field-effect transistor (MOSFET) like device named the metal-semiconductor-solution field-effect transistor (MSSFET) is implemented to control the ion diffusion current. When a negative gate voltage is applied, positive ions that travel along the nanochannel are confined to the central zone of the nanochannel allowing the radial Brownian Movements to be reduced. The effect is equivalent to an increase of the diffusion coefficient. However, a positive gate voltage can produce an opposite Zeta potential on the nanochannel surface. The cations in the nanochannel are dragged to the channel surface. This condition can be regarded as a decrease of the diffusion coefficient. Experimental results illustrate that the transfer characteristics of the MSSFET are similar to those of a p-channel depletion-type MOSFET. The ion diffusion coefficient in a nanochannel can be controlled when the the initial ion concentration difference across a nanochannel is larger than a certain threshold.
Yu-tze Tsai - One of the best experts on this subject based on the ideXlab platform.
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Measurement and control of the ion diffusion coefficient in a nanochannel
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, 2013Co-Authors: Yu-tze Tsai, Kang J. Chang, Gou-jen WangAbstract:In this study, we first propose a simple yet novel method to measure the diffusion coefficient of ions through a nanochannel. Back-side track etching is used for the fabrication of a nanochannel on an n-type silicon substrate. A metal-oxide semiconductor field-effect transistor (MOSFET) like device named the metal–semiconductor-solution field-effect transistor (MSSFET) is implemented to control the ion diffusion current. When a negative gate voltage is applied, positive ions that travel along the nanochannel are confined to the central zone of the nanochannel allowing the radial Brownian Movements to be reduced. The effect is equivalent to an increase of the diffusion coefficient. However, a positive gate voltage can produce an opposite Zeta potential on the nanochannel surface. The cations in the nanochannel are dragged to the channel surface. This condition can be regarded as a decrease of the diffusion coefficient. Experimental results illustrate that the transfer characteristics of the MSSFET are similar to those of a p-channel depletion-type MOSFET. The ion diffusion coefficient in a nanochannel can be controlled when the initial ion concentration difference across a nanochannel is larger than a certain threshold.
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Control of the ion diffusion coefficient in a nanochannel
2012 Symposium on Design Test Integration and Packaging of MEMS MOEMS, 2012Co-Authors: Yu-tze Tsai, Gou-jen WangAbstract:In this study, we first propose a simple yet novel method to measure the diffusion coefficient of ions through a nanochannel. Back-side track etching is used for the fabrication of a nanochannel on an n-type silicon substrate. A metal-oxide semiconductor field-effect transistor (MOSFET) like device named the metal-semiconductor-solution field-effect transistor (MSSFET) is implemented to control the ion diffusion current. When a negative gate voltage is applied, positive ions that travel along the nanochannel are confined to the central zone of the nanochannel allowing the radial Brownian Movements to be reduced. The effect is equivalent to an increase of the diffusion coefficient. However, a positive gate voltage can produce an opposite Zeta potential on the nanochannel surface. The cations in the nanochannel are dragged to the channel surface. This condition can be regarded as a decrease of the diffusion coefficient. Experimental results illustrate that the transfer characteristics of the MSSFET are similar to those of a p-channel depletion-type MOSFET. The ion diffusion coefficient in a nanochannel can be controlled when the the initial ion concentration difference across a nanochannel is larger than a certain threshold.
Tseng-hsin Wu - One of the best experts on this subject based on the ideXlab platform.
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Enhancement of Phase Change Heat Transfer by using Surface Energy Patterning Techniques
2006 1st IEEE International Conference on Nano Micro Engineered and Molecular Systems, 2006Co-Authors: Tseng-hsin WuAbstract:Using phase change of working fluid to remove heat in a heat exchanger device is a high efficiency method. When superheated vapor passes over a sub-cooled substrate, water droplets nucleate and grow by coalescence with the surrounding drops. The merging droplets exhibit two-dimensional random motion somewhat like the Brownian Movements of colloidal particles. If surface energy patterns are designed on the substrate surface, the random condensing droplets will nucleate and grow to a certain size and move toward the more hydrophilic side of the surface. Powered by this forces, condenser surface will not grow into film-wise condensation situation. Thus condensation speeds are faster than those of typical surfaces without any surface modification. This effect has implications for passively enhancing heat transfer in heat exchangers or heat pipes
Mitali Konwar - One of the best experts on this subject based on the ideXlab platform.
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investigation of time dependences of random force i n various colloidal suspension exhibiting Brownian Movements in the markoffian approximation
Advances in Applied Science Research, 2011Co-Authors: Mitali KonwarAbstract:The present work describes the nature of Brownian m ovement exhibited by colloidal suspensions. In the experiment we have used 5mW He- Ne laser light at 6328A and also Ar + laser light (green) to illuminate a sample cell containin g the liquid with colloidal suspensions of medicinal plants Alpine allughas, Murraya Koenigii( Linn), leucas cephalotes .The intensity fluctuations of the Brownian Movements are measured with the help of silicon photodiodes placed at particular positions and connected to a s ensitive digital multimeter. The readings are recorded with the help of a video camera [Model DCR -TRV 460 E Sony].The records of the fluctuations are taken for about two minutes and ar e transferred to a computer by USB cable. The fluctuating patterns per second are worked out with the help of a computer and they indicate the nature of particular colloidal suspensions. The intensity fluctuating patterns per second also exhibit the time dependence of the random force F v(t) which are characteristics of Brownian motion.
Shoji Takada - One of the best experts on this subject based on the ideXlab platform.
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Mechanism of Unidirectional Move of KIF1A Motor Studied by Coarse-Grained Simulations
Biophysical Journal, 2020Co-Authors: Ryo Kanada, Takeshi Kuwata, Hiroo Kenzaki, Shoji TakadaAbstract:KIF1A is a single-headed motor which can move unidirectionally along a microtubule (MT) using the chemical energy produced by ATP hydrolysis. Several experimental studies revealed that KIF1A makes the biased Brownian Movements (Okada et al., 2000). Fortunately, two major structures (ATP type and ADP type) are available. However, how KIF1A generates the translational movement from chemical reaction cycle still remains to be elucidated.To address this question we try to reproduce translational movement of KIF1A by coarse-grained simulation of the multiple-basin model (Okazaki et al., 2006) that realizes conformational change (Kikkawa et al., 2006) during ATP hydrolysis cycle.With a first set of simulations, ADP-type KIF1A detached from MT, diffused along MT, and attached to MT, but we did not find any forward bias in the stepping. We then found one condition that reproduces the biased Brownian movement. Namely, when a cargo (or a bead) with sufficiently large radius is attached to the C terminus of KIF1A, as in the in vivo situation, KIF1A exhibited the forward-biased Brownian movement along MT, in a consistent manner to experiments. In the presentation, we will also suggest the similarity of stepping mechanism between one-headed KIF1A motor and two-headed conventional kinesin.
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Structure-based Molecular Simulations Reveal the Enhancement of Biased Brownian Motions in Single-headed Kinesin
PLOS Computational Biology, 2013Co-Authors: Ryo Kanada, Takeshi Kuwata, Hiroo Kenzaki, Shoji TakadaAbstract:Kinesin is a family of molecular motors that move unidirectionally along microtubules (MT) using ATP hydrolysis free energy. In the family, the conventional two-headed kinesin was experimentally characterized to move unidirectionally through “walking” in a hand-over-hand fashion by coordinated motions of the two heads. Interestingly a single-headed kinesin, a truncated KIF1A, still can generate a biased Brownian movement along MT, as observed by in vitro single molecule experiments. Thus, KIF1A must use a different mechanism from the conventional kinesin to achieve the unidirectional motions. Based on the energy landscape view of proteins, for the first time, we conducted a set of molecular simulations of the truncated KIF1A Movements over an ATP hydrolysis cycle and found a mechanism exhibiting and enhancing stochastic forward-biased Movements in a similar way to those in experiments. First, simulating stand-alone KIF1A, we did not find any biased Movements, while we found that KIF1A with a large friction cargo-analog attached to the C-terminus can generate clearly biased Brownian Movements upon an ATP hydrolysis cycle. The linked cargo-analog enhanced the detachment of the KIF1A from MT. Once detached, diffusion of the KIF1A head was restricted around the large cargo which was located in front of the head at the time of detachment, thus generating a forward bias of the diffusion. The cargo plays the role of a diffusional anchor, or cane, in KIF1A “walking.”
