The Experts below are selected from a list of 106593 Experts worldwide ranked by ideXlab platform
Urs Von Stockar - One of the best experts on this subject based on the ideXlab platform.
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on line biomass monitoring of cho perfusion culture with scanning dielectric spectroscopy
Biotechnology and Bioengineering, 2003Co-Authors: Christopher Cannizzaro, Raphael Gugerli, I W Marison, Urs Von StockarAbstract:In this work, dielec. spectroscopy was used to monitor two CHO perfusion culture expts. (B14 and B16). The capacitance of the cell suspension was recorded every 20 min over an Excitation Frequency range of 0.2 MHz to 10.0 MHz. A phase plot of the capacitance at a low Excitation Frequency vs. the value at a higher Frequency proved to be an accurate indicator of the major transition points of the culture, i.e., max. cell viability, end of lactate consumption, point of zero viability. For both expts., the capacitance signal correlated very well (R2 >0.98) with viable cell no. up to concns. of 1 * 107 cells/mL. Visual observation of the capacitance spectra indicated that changes in the capacitance relative to Frequency were related to the cellular morphol. A multivariate model was developed using off-line data that could predict the median cell diam. within a single expt. (B14) with an error of 0.34 mm (2%). Upon extension to a subsequent expt. (B16), the predicted error was 1.18 mm (9%). [on SciFinder (R)]
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on line biomass monitoring of cho perfusion culture with scanning dielectric spectroscopy
Biotechnology and Bioengineering, 2003Co-Authors: Christopher Cannizzaro, Raphael Gugerli, I W Marison, Urs Von StockarAbstract:In this work, dielectric spectroscopy was used to monitor two CHO perfusion culture experiments (B14 and B16). The capacitance of the cell suspension was recorded every 20 minutes over an Excitation Frequency range of 0.2 MHz to 10.0 MHz. A phase plot of the capacitance at a low Excitation Frequency vs. the value at a higher Frequency proved to be an accurate indicator of the major transition points of the culture, i.e., maximum cell viability, end of lactate consumption, point of zero viability. For both experiments, the capacitance signal correlated very well (R(2) >0.98) with viable cell number up to concentrations of 1 x 10(7) cells/mL. Visual observation of the capacitance spectra indicated that changes in the capacitance relative to Frequency were related to the cellular morphology. A multivariate model was developed using off-line data that could predict the median cell diameter within a single experiment (B14) with an error of 0.34 microm (2%). Upon extension to a subsequent experiment (B16), the predicted error was 1.18 microm (9%).
Christopher Cannizzaro - One of the best experts on this subject based on the ideXlab platform.
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on line biomass monitoring of cho perfusion culture with scanning dielectric spectroscopy
Biotechnology and Bioengineering, 2003Co-Authors: Christopher Cannizzaro, Raphael Gugerli, I W Marison, Urs Von StockarAbstract:In this work, dielec. spectroscopy was used to monitor two CHO perfusion culture expts. (B14 and B16). The capacitance of the cell suspension was recorded every 20 min over an Excitation Frequency range of 0.2 MHz to 10.0 MHz. A phase plot of the capacitance at a low Excitation Frequency vs. the value at a higher Frequency proved to be an accurate indicator of the major transition points of the culture, i.e., max. cell viability, end of lactate consumption, point of zero viability. For both expts., the capacitance signal correlated very well (R2 >0.98) with viable cell no. up to concns. of 1 * 107 cells/mL. Visual observation of the capacitance spectra indicated that changes in the capacitance relative to Frequency were related to the cellular morphol. A multivariate model was developed using off-line data that could predict the median cell diam. within a single expt. (B14) with an error of 0.34 mm (2%). Upon extension to a subsequent expt. (B16), the predicted error was 1.18 mm (9%). [on SciFinder (R)]
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on line biomass monitoring of cho perfusion culture with scanning dielectric spectroscopy
Biotechnology and Bioengineering, 2003Co-Authors: Christopher Cannizzaro, Raphael Gugerli, I W Marison, Urs Von StockarAbstract:In this work, dielectric spectroscopy was used to monitor two CHO perfusion culture experiments (B14 and B16). The capacitance of the cell suspension was recorded every 20 minutes over an Excitation Frequency range of 0.2 MHz to 10.0 MHz. A phase plot of the capacitance at a low Excitation Frequency vs. the value at a higher Frequency proved to be an accurate indicator of the major transition points of the culture, i.e., maximum cell viability, end of lactate consumption, point of zero viability. For both experiments, the capacitance signal correlated very well (R(2) >0.98) with viable cell number up to concentrations of 1 x 10(7) cells/mL. Visual observation of the capacitance spectra indicated that changes in the capacitance relative to Frequency were related to the cellular morphology. A multivariate model was developed using off-line data that could predict the median cell diameter within a single experiment (B14) with an error of 0.34 microm (2%). Upon extension to a subsequent experiment (B16), the predicted error was 1.18 microm (9%).
Christoph Hollenstein - One of the best experts on this subject based on the ideXlab platform.
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dependence of intrinsic stress in hydrogenated amorphous silicon on Excitation Frequency in a plasma enhanced chemical vapor deposition process
Journal of Applied Physics, 1992Co-Authors: Joydeep Dutta, U Kroll, Patrick Chabloz, A A Howling, J L Dorier, Arvind Shah, Christoph HollensteinAbstract:Dependence of intrinsic stress in hydrogenated amorphous silicon on Excitation Frequency in a plasma-enhanced chemical vapor deposition process
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influences of a high Excitation Frequency 70 mhz in the glow discharge technique on the process plasma and the properties of hydrogenated amorphous silicon
Journal of Applied Physics, 1992Co-Authors: Friedhelm Finger, V Viret, X M Tang, Wolfhard Beyer, U Kroll, A A Howling, Arvind Shah, J. Weber, Christoph HollensteinAbstract:Hydrogenated amorphous silicon has been prepared at a plasma Excitation Frequency in the very‐high‐Frequency band at 70 MHz with the glow discharge technique at substrate temperatures between 280 and 50 °C. The structural properties have been studied using hydrogen evolution, elastic recoil detection analysis, and infrared spectroscopy. The films were further characterized by dark and photoconductivity and by photothermal deflection spectroscopy. With respect to films prepared at the conventional Frequency of 13.56 MHz considerable differences concerning the electronic and structural properties are observed as the substrate temperature is decreased from 280 to 50 °C. Down to a substrate temperature of 150 °C the electronic film properties change only a little and the total hydrogen content cH and the degree of microstructure that can be directly correlated to cH increase only moderately. Below 150 °C the electronic properties deteriorate in the usual manner but still the total hydrogen content does not ex...
Friedhelm Finger - One of the best experts on this subject based on the ideXlab platform.
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structure and growth of hydrogenated microcrystalline silicon investigation by transmission electron microscopy and raman spectroscopy of films grown at different plasma Excitation frequencies
Philosophical Magazine, 1997Co-Authors: M Luysberg, P Hapke, Reinhard Carius, Friedhelm FingerAbstract:Abstract Microcrystalline silicon prepared by plasma-enhanced chemical vapour deposition consists of variable volume fractions of amorphous phase, grain boundaries, cavities and crystalline grains. In this paper the structural properties, which strongly depend on the growth conditions, were investigated in detail by transmission electron microscopy and by Raman spectroscopy. A columnar structure parallel to the growth direction is observed for all conditions investigated. By increasing the plasma Excitation Frequency the crystalline volume fraction and the grain sizes are enhanced. Simultaneously an increase in the growth rate can be achieved, which is accompanied by an increasing etch rate of amorphous material. In addition, spherical voids were found predominantly in samples prepared at a low plasma Excitation Frequency. The growth of a porous initial layer containing a high density of ‘crack-line’ voids is observed when high plasma Excitation frequencies are applied. These results suggest that the micr...
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improvement of grain size and deposition rate of microcrystalline silicon by use of very high Frequency glow discharge
Applied Physics Letters, 1994Co-Authors: Friedhelm Finger, M Luysberg, P Hapke, H Wagner, Reinhard Carius, M ScheibAbstract:The influence of the plasma Excitation Frequency on the growth conditions and the material properties of microcrystalline silicon prepared by plasma enhanced chemical vapor deposition at low deposition temperature is investigated. It is found that an increase of the plasma Excitation Frequency leads to a simultaneous increase of the growth rate, the grain size, and the Hall mobility of microcrystalline silicon. This is attributed to an effective selective etching of disordered material creating more space to develop crystalline grains, while also more species for faster growth of the crystallites are available.
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influences of a high Excitation Frequency 70 mhz in the glow discharge technique on the process plasma and the properties of hydrogenated amorphous silicon
Journal of Applied Physics, 1992Co-Authors: Friedhelm Finger, V Viret, X M Tang, Wolfhard Beyer, U Kroll, A A Howling, Arvind Shah, J. Weber, Christoph HollensteinAbstract:Hydrogenated amorphous silicon has been prepared at a plasma Excitation Frequency in the very‐high‐Frequency band at 70 MHz with the glow discharge technique at substrate temperatures between 280 and 50 °C. The structural properties have been studied using hydrogen evolution, elastic recoil detection analysis, and infrared spectroscopy. The films were further characterized by dark and photoconductivity and by photothermal deflection spectroscopy. With respect to films prepared at the conventional Frequency of 13.56 MHz considerable differences concerning the electronic and structural properties are observed as the substrate temperature is decreased from 280 to 50 °C. Down to a substrate temperature of 150 °C the electronic film properties change only a little and the total hydrogen content cH and the degree of microstructure that can be directly correlated to cH increase only moderately. Below 150 °C the electronic properties deteriorate in the usual manner but still the total hydrogen content does not ex...
I W Marison - One of the best experts on this subject based on the ideXlab platform.
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on line biomass monitoring of cho perfusion culture with scanning dielectric spectroscopy
Biotechnology and Bioengineering, 2003Co-Authors: Christopher Cannizzaro, Raphael Gugerli, I W Marison, Urs Von StockarAbstract:In this work, dielec. spectroscopy was used to monitor two CHO perfusion culture expts. (B14 and B16). The capacitance of the cell suspension was recorded every 20 min over an Excitation Frequency range of 0.2 MHz to 10.0 MHz. A phase plot of the capacitance at a low Excitation Frequency vs. the value at a higher Frequency proved to be an accurate indicator of the major transition points of the culture, i.e., max. cell viability, end of lactate consumption, point of zero viability. For both expts., the capacitance signal correlated very well (R2 >0.98) with viable cell no. up to concns. of 1 * 107 cells/mL. Visual observation of the capacitance spectra indicated that changes in the capacitance relative to Frequency were related to the cellular morphol. A multivariate model was developed using off-line data that could predict the median cell diam. within a single expt. (B14) with an error of 0.34 mm (2%). Upon extension to a subsequent expt. (B16), the predicted error was 1.18 mm (9%). [on SciFinder (R)]
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on line biomass monitoring of cho perfusion culture with scanning dielectric spectroscopy
Biotechnology and Bioengineering, 2003Co-Authors: Christopher Cannizzaro, Raphael Gugerli, I W Marison, Urs Von StockarAbstract:In this work, dielectric spectroscopy was used to monitor two CHO perfusion culture experiments (B14 and B16). The capacitance of the cell suspension was recorded every 20 minutes over an Excitation Frequency range of 0.2 MHz to 10.0 MHz. A phase plot of the capacitance at a low Excitation Frequency vs. the value at a higher Frequency proved to be an accurate indicator of the major transition points of the culture, i.e., maximum cell viability, end of lactate consumption, point of zero viability. For both experiments, the capacitance signal correlated very well (R(2) >0.98) with viable cell number up to concentrations of 1 x 10(7) cells/mL. Visual observation of the capacitance spectra indicated that changes in the capacitance relative to Frequency were related to the cellular morphology. A multivariate model was developed using off-line data that could predict the median cell diameter within a single experiment (B14) with an error of 0.34 microm (2%). Upon extension to a subsequent experiment (B16), the predicted error was 1.18 microm (9%).
