The Experts below are selected from a list of 163080 Experts worldwide ranked by ideXlab platform
Shinya Teramachi - One of the best experts on this subject based on the ideXlab platform.
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Direction of Temperature Gradient and retention mechanism in normal-phase Temperature Gradient interaction chromatography for poly(methyl methacrylate) fractionation
Polymer Journal, 2007Co-Authors: Hiroshi Matsumoto, Tadatomo Kawai, Shinya TeramachiAbstract:Direction of Temperature Gradient and Retention Mechanism in Normal-Phase Temperature Gradient Interaction Chromatography for Poly(methyl methacrylate) Fractionation
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Direction of Temperature Gradient for normal-phase Temperature Gradient interaction chromatography in polystyrene fractionation
Journal of chromatography. A, 2005Co-Authors: Shinya Teramachi, Hiroshi Matsumoto, Tadatomo KawaiAbstract:Abstract Temperature Gradient interaction chromatography (TGIC) is a powerful technique for molecular weight fractionation of polymers, in which the interaction strength is controlled by varying the column Temperature. In the present paper, the effects of the sign of the Temperature dependence of the retention and the direction of the Temperature Gradient (raising or lowering) on TGIC in the normal-phase mode were studied for the molecular weight fractionation of polystyrene samples in organic mobile phases. It was found that a positive Temperature Gradient was effective in the system consisting of amino-modified silica (NH2) column and the eluent mixture of tetrahydrofuran and n-hexane where retention decreased with increasing Temperature. A negative Temperature Gradient was effective for the systems consisting of a bare-silica column//chloroform/n-hexane and NH2-column//chloroform/n-hexane, where retention increased with increasing Temperature. Increasing retention with increasing Temperature has been found, so far, only for a water-soluble polymer (PEO) in an aqueous mobile phase in RP-TGIC.
Frank Jenko - One of the best experts on this subject based on the ideXlab platform.
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Short wavelength ion Temperature Gradient turbulence
Physics of Plasmas, 2012Co-Authors: J. Chowdhury, Stephan Brunner, R. Ganesh, X. Lapillonne, Laurent Villard, Frank JenkoAbstract:The ion Temperature Gradient (ITG) mode in the high wavenumber regime (k(y)rho(s) > 1), referred to as short wavelength ion Temperature Gradient mode (SWITG) is studied using the nonlinear gyrokinetic electromagnetic code GENE. It is shown that, although the SWITG mode may be linearly more unstable than the standard long wavelength (k(y)rho(s) < 1) ITG mode, nonlinearly its contribution to the total thermal ion heat transport is found to be low. We interpret this as resulting from an increased zonal flow shearing effect on the SWITG mode suppression. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4759458]
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critical Gradient formula for toroidal electron Temperature Gradient modes
Physics of Plasmas, 2001Co-Authors: Frank Jenko, William Dorland, G W HammettAbstract:Under certain conditions, the electron heat transport induced by electron Temperature Gradient (ETG) streamers is sufficiently large and sensitive with respect to the normalized electron Temperature Gradient to represent a possible cause for electron Temperature profile consistency (“stiffness”). Here, linear gyrokinetic simulations of toroidal ETG modes in tokamak core and edge plasmas are presented. An algebraic formula for the threshold of the linear instability is derived from the numerical solutions of the linear gyrokinetic equations which recovers previous analytical results in the appropriate limits.
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Electron Temperature Gradient turbulence.
Physical Review Letters, 2000Co-Authors: William Dorland, Frank Jenko, M T Kotschenreuther, B. N. RogersAbstract:The first toroidal, gyrokinetic, electromagnetic simulations of small scale plasma turbulence are presented. The turbulence considered is driven by Gradients in the electron Temperature. It is found that electron Temperature Gradient (ETG) turbulence can induce experimentally relevant thermal losses in magnetic confinement fusion devices. For typical tokamak parameters, the transport is essentially electrostatic in character. The simulation results are qualitatively consistent with a model that balances linear and secondary mode growth rates. Significant streamer-dominated transport at long wavelengths occurs because the secondary modes that produce saturation become weak in the ETG limit.
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electron Temperature Gradient driven turbulence
Physics of Plasmas, 2000Co-Authors: Frank Jenko, William Dorland, M T Kotschenreuther, B. N. RogersAbstract:Collisionless electron-Temperature-Gradient-driven (ETG) turbulence in toroidal geometry is studied via nonlinear numerical simulations. To this aim, two massively parallel, fully gyrokinetic Vlasov codes are used, both including electromagnetic effects. Somewhat surprisingly, and unlike in the analogous case of ion-Temperature-Gradient-driven (ITG) turbulence, we find that the turbulent electron heat flux is significantly underpredicted by simple mixing length estimates in a certain parameter regime (ŝ∼1, low α). This observation is directly linked to the presence of radially highly elongated vortices (“streamers”) which lead to very effective cross-field transport. The simulations therefore indicate that ETG turbulence is likely to be relevant to magnetic confinement fusion experiments.
Tadatomo Kawai - One of the best experts on this subject based on the ideXlab platform.
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Direction of Temperature Gradient and retention mechanism in normal-phase Temperature Gradient interaction chromatography for poly(methyl methacrylate) fractionation
Polymer Journal, 2007Co-Authors: Hiroshi Matsumoto, Tadatomo Kawai, Shinya TeramachiAbstract:Direction of Temperature Gradient and Retention Mechanism in Normal-Phase Temperature Gradient Interaction Chromatography for Poly(methyl methacrylate) Fractionation
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Direction of Temperature Gradient for normal-phase Temperature Gradient interaction chromatography in polystyrene fractionation
Journal of chromatography. A, 2005Co-Authors: Shinya Teramachi, Hiroshi Matsumoto, Tadatomo KawaiAbstract:Abstract Temperature Gradient interaction chromatography (TGIC) is a powerful technique for molecular weight fractionation of polymers, in which the interaction strength is controlled by varying the column Temperature. In the present paper, the effects of the sign of the Temperature dependence of the retention and the direction of the Temperature Gradient (raising or lowering) on TGIC in the normal-phase mode were studied for the molecular weight fractionation of polystyrene samples in organic mobile phases. It was found that a positive Temperature Gradient was effective in the system consisting of amino-modified silica (NH2) column and the eluent mixture of tetrahydrofuran and n-hexane where retention decreased with increasing Temperature. A negative Temperature Gradient was effective for the systems consisting of a bare-silica column//chloroform/n-hexane and NH2-column//chloroform/n-hexane, where retention increased with increasing Temperature. Increasing retention with increasing Temperature has been found, so far, only for a water-soluble polymer (PEO) in an aqueous mobile phase in RP-TGIC.
B. N. Rogers - One of the best experts on this subject based on the ideXlab platform.
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Electron Temperature Gradient turbulence.
Physical Review Letters, 2000Co-Authors: William Dorland, Frank Jenko, M T Kotschenreuther, B. N. RogersAbstract:The first toroidal, gyrokinetic, electromagnetic simulations of small scale plasma turbulence are presented. The turbulence considered is driven by Gradients in the electron Temperature. It is found that electron Temperature Gradient (ETG) turbulence can induce experimentally relevant thermal losses in magnetic confinement fusion devices. For typical tokamak parameters, the transport is essentially electrostatic in character. The simulation results are qualitatively consistent with a model that balances linear and secondary mode growth rates. Significant streamer-dominated transport at long wavelengths occurs because the secondary modes that produce saturation become weak in the ETG limit.
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electron Temperature Gradient driven turbulence
Physics of Plasmas, 2000Co-Authors: Frank Jenko, William Dorland, M T Kotschenreuther, B. N. RogersAbstract:Collisionless electron-Temperature-Gradient-driven (ETG) turbulence in toroidal geometry is studied via nonlinear numerical simulations. To this aim, two massively parallel, fully gyrokinetic Vlasov codes are used, both including electromagnetic effects. Somewhat surprisingly, and unlike in the analogous case of ion-Temperature-Gradient-driven (ITG) turbulence, we find that the turbulent electron heat flux is significantly underpredicted by simple mixing length estimates in a certain parameter regime (ŝ∼1, low α). This observation is directly linked to the presence of radially highly elongated vortices (“streamers”) which lead to very effective cross-field transport. The simulations therefore indicate that ETG turbulence is likely to be relevant to magnetic confinement fusion experiments.
Yu-chong Tai - One of the best experts on this subject based on the ideXlab platform.
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An integrated system for on-chip Temperature Gradient interaction chromatography
Sensors and Actuators A: Physical, 2006Co-Authors: Chi-yuan Shih, Yang Chen, Jun Xie, Yu-chong TaiAbstract:This paper reports the first integrated MEMS high performance liquid chromatography (HPLC) chip that consists of a parylene high-pressure liquid chromatography (LC) column, an electrochemical sensor, a resistive heater and a thermal-isolation structure for on-chip Temperature Gradient interaction chromatography (TGIC) application. Two sets of devices for different chromatography criteria were fabricated. The separation column was 8-mm long, 100-μm wide, 25-μm high and was packed with 5-μm sized, C18-coated beads using conventional slurry-packing technique. A novel parylene-enhanced air-gap thermal isolation technology was used to reduce heater power consumption by 58% and to reduce Temperature rise in the off-column area by 67%. To test the chromatography performance of the fabricated system, a mixture of derivatized amino acids was chosen for separation. A temporal Temperature Gradient scanning from 25 °C to 65 °C with a ramping rate of 3.6 °C/min was applied to the column during separation. Successful chromatographic separation of derivatized amino acids was obtained on the chip. Compared with conventional Temperature Gradient HPLC system which incorporates “macro oven” to generate temporal Temperature Gradient on the column, our chip's thermal performance, i.e., power consumption and thermal response, is greatly improved without sacrificing chromatography quality.
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On-chip Temperature Gradient interaction chromatography
Journal of Chromatography A, 2006Co-Authors: Chi-yuan Shih, Yang Chen, Jun Xie, Yu-chong TaiAbstract:This paper reports the first integrated microelectromechanical system (MEMS) HPLC chip that consists of a parylene high-pressure LC column, an electrochemical sensor, a resistive heater and a thermal-isolation structure for on-chip Temperature Gradient interaction chromatography application. The separation column was 8 mm long, 100 μm wide, 25 μm high and was packed with 5 μm sized, C18-coated beads using conventional slurry-packing technique. A novel parylene-enhanced, air-gap thermal isolation technology was used to reduce heater power consumption by 58% and to reduce Temperature rise in the off-column area by 67%. The fabricated chip consumed 400 mW when operated at 100 °C. To test the chromatography performance of the fabricated system, a mixture of derivatized amino acids was chosen for separation. A temporal Temperature Gradient scanning from 25 to 65 °C with a ramping rate of 3.6 °C/min was applied to the column during separation. Successful chromatographic separation of derivatized amino acids was carried out using our chip. Compared with conventional Temperature Gradient HPLC system which incorporates “macro oven” to generate temporal Temperature Gradient on the column, our chip's thermal performance, i.e., power consumption and thermal response, is greatly improved without sacrificing chromatography quality.
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On-chip Temperature Gradient liquid chromatography
18th IEEE International Conference on Micro Electro Mechanical Systems 2005. MEMS 2005., 1Co-Authors: Chi-yuan Shih, Yang Chen, Jun Xie, Yu-chong TaiAbstract:We report here the first MEMS Temperature-programmable high pressure parylene column with integrated thermal isolation and electrochemical sensor for on-chip Temperature Gradient liquid chromatography. Two sets of devices for different high performance liquid chromatography (HPLC) criteria were fabricated. The separation and detection of derivatized amino acids sample was successfully demonstrated. Compared with other Temperature Gradient HPLC systems which use "macro oven" to generate temporal Temperature Gradient in the column, our device's thermal performance is greatly improved by orders of magnitude without the sacrifice of chromatography quality.
