The Experts below are selected from a list of 29175 Experts worldwide ranked by ideXlab platform
M F Lawrence - One of the best experts on this subject based on the ideXlab platform.
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direct detection of the hybridization of synthetic homo oligomer dna sequences by field effect
Journal of Physical Chemistry B, 1997Co-Authors: E Souteyrand, J P Cloarec, J R Martin, C Wilson, I Lawrence, And S Mikkelsen, M F LawrenceAbstract:Homo-oligomer DNA strands were immobilized onto silicon/silicon dioxide electrodes using 3-aminopropyltriethoxysilane. These modified substrates were used as working electrodes in a three-electrode electrochemical cell. In-phase and out-of-phase impedances were measured in the range −1 to +1 V with respect to an Ag/AgCl reference electrode, with a superimposed 10 mV Ac Signal at frequencies of 20 and 100 kHz. Ex situ hybridization with complementary oligomer strands, performed at the surfAce of modified electrodes, is clearly reflected by negative shifts of about 100 mV in the flat-band potential of the semiconductor. Consecutive hybridization−denaturation steps show that the shifts are reproducible and the process is reversible. The in situ hybridization of complementary strands has also been observed with impedance measurements at Si/SiO2 substrates and with the use of a field effect device. The direct detection of hybridization with a field effect device was performed under constant drain current mode,...
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direct detection of the hybridization of synthetic homo oligomer dna sequences by field effect
Journal of Physical Chemistry B, 1997Co-Authors: E Souteyrand, J P Cloarec, J R Martin, C Wilson, I Lawrence, And S Mikkelsen, M F LawrenceAbstract:Homo-oligomer DNA strands were immobilized onto silicon/silicon dioxide electrodes using 3-aminopropyltriethoxysilane. These modified substrates were used as working electrodes in a three-electrode electrochemical cell. In-phase and out-of-phase impedances were measured in the range −1 to +1 V with respect to an Ag/AgCl reference electrode, with a superimposed 10 mV Ac Signal at frequencies of 20 and 100 kHz. Ex situ hybridization with complementary oligomer strands, performed at the surfAce of modified electrodes, is clearly reflected by negative shifts of about 100 mV in the flat-band potential of the semiconductor. Consecutive hybridization−denaturation steps show that the shifts are reproducible and the process is reversible. The in situ hybridization of complementary strands has also been observed with impedance measurements at Si/SiO2 substrates and with the use of a field effect device. The direct detection of hybridization with a field effect device was performed under constant drain current mode,...
E Souteyrand - One of the best experts on this subject based on the ideXlab platform.
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direct detection of the hybridization of synthetic homo oligomer dna sequences by field effect
Journal of Physical Chemistry B, 1997Co-Authors: E Souteyrand, J P Cloarec, J R Martin, C Wilson, I Lawrence, And S Mikkelsen, M F LawrenceAbstract:Homo-oligomer DNA strands were immobilized onto silicon/silicon dioxide electrodes using 3-aminopropyltriethoxysilane. These modified substrates were used as working electrodes in a three-electrode electrochemical cell. In-phase and out-of-phase impedances were measured in the range −1 to +1 V with respect to an Ag/AgCl reference electrode, with a superimposed 10 mV Ac Signal at frequencies of 20 and 100 kHz. Ex situ hybridization with complementary oligomer strands, performed at the surfAce of modified electrodes, is clearly reflected by negative shifts of about 100 mV in the flat-band potential of the semiconductor. Consecutive hybridization−denaturation steps show that the shifts are reproducible and the process is reversible. The in situ hybridization of complementary strands has also been observed with impedance measurements at Si/SiO2 substrates and with the use of a field effect device. The direct detection of hybridization with a field effect device was performed under constant drain current mode,...
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direct detection of the hybridization of synthetic homo oligomer dna sequences by field effect
Journal of Physical Chemistry B, 1997Co-Authors: E Souteyrand, J P Cloarec, J R Martin, C Wilson, I Lawrence, And S Mikkelsen, M F LawrenceAbstract:Homo-oligomer DNA strands were immobilized onto silicon/silicon dioxide electrodes using 3-aminopropyltriethoxysilane. These modified substrates were used as working electrodes in a three-electrode electrochemical cell. In-phase and out-of-phase impedances were measured in the range −1 to +1 V with respect to an Ag/AgCl reference electrode, with a superimposed 10 mV Ac Signal at frequencies of 20 and 100 kHz. Ex situ hybridization with complementary oligomer strands, performed at the surfAce of modified electrodes, is clearly reflected by negative shifts of about 100 mV in the flat-band potential of the semiconductor. Consecutive hybridization−denaturation steps show that the shifts are reproducible and the process is reversible. The in situ hybridization of complementary strands has also been observed with impedance measurements at Si/SiO2 substrates and with the use of a field effect device. The direct detection of hybridization with a field effect device was performed under constant drain current mode,...
Graham R Cooks - One of the best experts on this subject based on the ideXlab platform.
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calibration procedure for secular frequency scanning in ion trap mass spectrometers
Rapid Communications in Mass Spectrometry, 2016Co-Authors: Dalton T Snyder, Christopher J Pulliam, Graham R CooksAbstract:Rationale Mass spectra can be recorded using ion traps by scanning the frequency of an alternating current (Ac) Signal that corresponds to the secular frequency of a trapped ion. There is a considerable simplification in the instrumentation needed to perform such a scan compared with conventional scans of the radiofrequency (rf) amplitude. However, mass calibration is difficult. An algorithm that can be used to Achieve mass calibration is investigated and the fActors that affect ion mass assignments are discussed. Methods Time domain data, recorded using a commercial benchtop linear ion trap mass spectrometer, are converted to the m/z domain using ion Mathieu parameter qu values which are derived from the dimensionless frequency parameter βu expressed as a continuing frAction in terms of qu. The relationship between the operating parameters of an ideal ion trap and the ion m/z ratio is derived from the Mathieu equations and expressed as an algorithm which through successive approximations yields the Mathieu qu value and hence m/z values and peak widths. The predictions of the algorithm are tested against experiment by sweeping the frequency of a small supplementary Ac Signal so as to cause mass-selective ejection of trapped ions. Results Calibration AccurAcy is always better than 0.1%, often much better. Peak widths correspond to a mass resolution of 250 to 500 in the m/z 100–1800 range in secular frequency scans. Conclusions A simple, effective method of calibration of mass spectra recorded using secular frequency scans is Achieved. The effects of rf amplitude, scan rate, and Ac amplitude on calibration parameters are shown using LTQ linear ion trap data. Corrections for differences in ion mass must be made for Accurate calibration, and this is easily incorporated into the calibration procedure. Copyright © 2016 John Wiley & Sons, Ltd.
Daniel E Austin - One of the best experts on this subject based on the ideXlab platform.
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coaxial ion trap mass spectrometer concentric toroidal and quadrupolar trapping regions
Analytical Chemistry, 2011Co-Authors: Ying Peng, Aaron R Hawkins, Brett J Hansen, Hannah Quist, Zhiping Zhang, Miao Wang, Daniel E AustinAbstract:We present the design and results for a new radio-frequency ion trap mass analyzer, the coaxial ion trap, in which both toroidal and quadrupolar trapping regions are created simultaneously. The device is composed of two parallel ceramic plates, the fAcing surfAces of which are lithographically patterned with concentric metal rings and covered with a thin film of germanium. Experiments demonstrate that ions can be trapped in either region, transferred from the toroidal to the quadrupolar region, and mass-selectively ejected from the quadrupolar region to a detector. Ions trapped in the toroidal region can be transferred to the quadrupole region using an applied Ac Signal in the radial direction, although it appears that the mechanism of this transfer does not involve resonance with the ion secular frequency, and the process is not mass selective. Ions in the quadrupole trapping region are mass analyzed using dipole resonant ejection. Multiple transfer steps and mass analysis scans are possible on a single ...
J P Cloarec - One of the best experts on this subject based on the ideXlab platform.
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direct detection of the hybridization of synthetic homo oligomer dna sequences by field effect
Journal of Physical Chemistry B, 1997Co-Authors: E Souteyrand, J P Cloarec, J R Martin, C Wilson, I Lawrence, And S Mikkelsen, M F LawrenceAbstract:Homo-oligomer DNA strands were immobilized onto silicon/silicon dioxide electrodes using 3-aminopropyltriethoxysilane. These modified substrates were used as working electrodes in a three-electrode electrochemical cell. In-phase and out-of-phase impedances were measured in the range −1 to +1 V with respect to an Ag/AgCl reference electrode, with a superimposed 10 mV Ac Signal at frequencies of 20 and 100 kHz. Ex situ hybridization with complementary oligomer strands, performed at the surfAce of modified electrodes, is clearly reflected by negative shifts of about 100 mV in the flat-band potential of the semiconductor. Consecutive hybridization−denaturation steps show that the shifts are reproducible and the process is reversible. The in situ hybridization of complementary strands has also been observed with impedance measurements at Si/SiO2 substrates and with the use of a field effect device. The direct detection of hybridization with a field effect device was performed under constant drain current mode,...
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direct detection of the hybridization of synthetic homo oligomer dna sequences by field effect
Journal of Physical Chemistry B, 1997Co-Authors: E Souteyrand, J P Cloarec, J R Martin, C Wilson, I Lawrence, And S Mikkelsen, M F LawrenceAbstract:Homo-oligomer DNA strands were immobilized onto silicon/silicon dioxide electrodes using 3-aminopropyltriethoxysilane. These modified substrates were used as working electrodes in a three-electrode electrochemical cell. In-phase and out-of-phase impedances were measured in the range −1 to +1 V with respect to an Ag/AgCl reference electrode, with a superimposed 10 mV Ac Signal at frequencies of 20 and 100 kHz. Ex situ hybridization with complementary oligomer strands, performed at the surfAce of modified electrodes, is clearly reflected by negative shifts of about 100 mV in the flat-band potential of the semiconductor. Consecutive hybridization−denaturation steps show that the shifts are reproducible and the process is reversible. The in situ hybridization of complementary strands has also been observed with impedance measurements at Si/SiO2 substrates and with the use of a field effect device. The direct detection of hybridization with a field effect device was performed under constant drain current mode,...
