The Experts below are selected from a list of 47769 Experts worldwide ranked by ideXlab platform
Mathias Choquer - One of the best experts on this subject based on the ideXlab platform.
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deletion of a mfs transporter like gene in cercospora nicotianae reduces cercosporin toxin accumulation and fungal virulence
FEBS Letters, 2007Co-Authors: Mathias ChoquerAbstract:Many phytopathogenic Cercospora species produce a host-nonselective polyketide toxin, called cercosporin, whose toxicity exclusively relies on the generation of reactive oxygen species. Here, we describe a Cercospora nicotianae CTB4 gene that encodes a putative membrane transporter and provide genetic evidence to support its role in cercosporin accumulation. The predicted CTB4 polypeptide has 12 transmembrane segments with four conserved motifs and has considerable similarity to a wide range of transporters belonging to the major facilitator superfamily (MFS). Disruption of the CTB4 gene resulted in a mutant that displayed a drastic reduction of cercosporin production and accumulation of an unknown brown pigment. Cercosporin was detected largely from fungal hyphae of ctb4 disruptants, but not from the surrounding medium, suggesting that the mutants were defective in both cercosporin biosynthesis and secretion. Cercosporin purified from the ctb4 disruptants exhibited toxicity to tobacco suspension cells, insignificantly different from wild-type, whereas the disruptants formed fewer lesions on tobacco leaves. The ctb4 null mutants retained normal resistance to cercosporin and other singlet oxygen-generating photosensitizers, indistinguishable from the parental Strain. Transformation of a functional CTB4 clone into a ctb4 null mutant fully revived cercosporin production. Thus, we propose that the CTB4 gene encodes a putative MFS transporter responsible for secretion and accumulation of cercosporin.
Hyung-joon Bang - One of the best experts on this subject based on the ideXlab platform.
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real time deformed shape estimation of a wind turbine blade using distributed fiber bragg grating sensors
Wind Energy, 2013Co-Authors: Hongil Kim, Jae-hung Han, Hyung-joon BangAbstract:This study presents a real-time shape estimation technique based on measured Strains at multiple points. For the measurement of multiple Strain data, fiber Bragg grating (FBG) sensors are used because of their excellent Strain accuracy and multiplexing capability with minimal mechanical loading. The displacement-Strain relation of a blade structure is systematically formulated using a finite element model, where the locations and directions of the FBG sensors are taken into account. Because there could be unavoidable modeling uncertainties, the operational modal analysis is also introduced to construct a displacement-Strain Transformation matrix. In the laboratory, the developed technique is applied to a wind turbine blade in which the FBG sensors are embedded. The blade deformation is reconstructed using the proposed method when the blade is subjected to static and vibratory loadings. At the same time, a stereo pattern recognition system consisting of eight cameras directly captures the deformation of the blade to validate the estimated blade shapes. For various loading cases, the estimated results of the blade shape agree very well with the reference measurements. Copyright © 2013 John Wiley & Sons, Ltd.
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Measurement of Strain and bending deflection of a wind turbine tower using arrayed FBG sensors
International Journal of Precision Engineering and Manufacturing, 2012Co-Authors: Hyung-joon BangAbstract:This paper introduces a fiber Bragg grating (FBG) based arrayed sensor system for use in the measurement of Strain and bending deflection of an 1.5 MW wind turbine tower, and describes the results of field tests of structural monitoring of turbine start and feathering load conditions. A wavelength division multiplexing (WDM) FBG interrogator was developed with a spectrometer-type demodulator based on a linear photo detector for high-speed Strain sensing. Real-time shape estimation of the wind turbine tower was accomplished using Strain data gathered by surface mounted fiber Bragg grating sensors. The finite element model of the wind turbine tower was created and the displacement-Strain Transformation (DST) matrix on the basis of the modal approach was obtained. To monitor the dynamic structural behavior of the wind turbine, 10 FBG sensors were arrayed and installed on the inner surface of the tower located at the primary wind direction. The time histories of the Strain were gathered using the FBG sensors and the deflections of the tower top position were simultaneously transformed using the DST matrix. Finally, the full deflection shapes of the tower were successfully estimated using arrayed FBG sensors.
Jae-hung Han - One of the best experts on this subject based on the ideXlab platform.
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real time deformed shape estimation of a wind turbine blade using distributed fiber bragg grating sensors
Wind Energy, 2013Co-Authors: Hongil Kim, Jae-hung Han, Hyung-joon BangAbstract:This study presents a real-time shape estimation technique based on measured Strains at multiple points. For the measurement of multiple Strain data, fiber Bragg grating (FBG) sensors are used because of their excellent Strain accuracy and multiplexing capability with minimal mechanical loading. The displacement-Strain relation of a blade structure is systematically formulated using a finite element model, where the locations and directions of the FBG sensors are taken into account. Because there could be unavoidable modeling uncertainties, the operational modal analysis is also introduced to construct a displacement-Strain Transformation matrix. In the laboratory, the developed technique is applied to a wind turbine blade in which the FBG sensors are embedded. The blade deformation is reconstructed using the proposed method when the blade is subjected to static and vibratory loadings. At the same time, a stereo pattern recognition system consisting of eight cameras directly captures the deformation of the blade to validate the estimated blade shapes. For various loading cases, the estimated results of the blade shape agree very well with the reference measurements. Copyright © 2013 John Wiley & Sons, Ltd.
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displacement field estimation for a two dimensional structure using fiber bragg grating sensors
Smart Materials and Structures, 2009Co-Authors: Stephan Rapp, Lae-hyong Kang, Jae-hung Han, Uwe C Mueller, Horst BaierAbstract:The structure shape itself is of great interest for many aerospace applications. For example, the stability of the surface shape of large, high precision or space reflectors is essential for the communication performance. The knowledge of static and dynamic displacements of these structures would provide the possibility to enhance their performance by appropriate countermeasures. During operation, however, the direct measurement of displacements of the whole structure is often difficult. This study investigates whole displacement field estimation using Strain measurement and a displacement–Strain-Transformation approach. The use of fiber Bragg gratings (FBGs) as Strain sensors for this application offers the possible implementation of an integrated sensor network including many measurement points within only a few optical fibers. This paper discusses many issues related to the displacement field estimation of a dynamically excited plate using a Transformation matrix based on a modal approach. In order to reduce systematic displacement estimation errors due to aliasing, a parametric study was performed and the sensor locations were optimized. Experimental validation was also conducted using a cantilever plate equipped with 16 FBG sensors in an optimized configuration. The estimated displacements showed good agreements with those measured directly from laser displacement sensors.
Horst Baier - One of the best experts on this subject based on the ideXlab platform.
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displacement field estimation for a two dimensional structure using fiber bragg grating sensors
Smart Materials and Structures, 2009Co-Authors: Stephan Rapp, Lae-hyong Kang, Jae-hung Han, Uwe C Mueller, Horst BaierAbstract:The structure shape itself is of great interest for many aerospace applications. For example, the stability of the surface shape of large, high precision or space reflectors is essential for the communication performance. The knowledge of static and dynamic displacements of these structures would provide the possibility to enhance their performance by appropriate countermeasures. During operation, however, the direct measurement of displacements of the whole structure is often difficult. This study investigates whole displacement field estimation using Strain measurement and a displacement–Strain-Transformation approach. The use of fiber Bragg gratings (FBGs) as Strain sensors for this application offers the possible implementation of an integrated sensor network including many measurement points within only a few optical fibers. This paper discusses many issues related to the displacement field estimation of a dynamically excited plate using a Transformation matrix based on a modal approach. In order to reduce systematic displacement estimation errors due to aliasing, a parametric study was performed and the sensor locations were optimized. Experimental validation was also conducted using a cantilever plate equipped with 16 FBG sensors in an optimized configuration. The estimated displacements showed good agreements with those measured directly from laser displacement sensors.
Denis Pompon - One of the best experts on this subject based on the ideXlab platform.
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enhanced in vivo monooxygenase activities of mammalian p450s in engineered yeast cells producing high levels of nadph p450 reductase and human cytochrome b5
Gene, 1993Co-Authors: Gilles Truan, Christophe Cullin, Philippe Reisdorf, Philippe Urban, Denis PomponAbstract:We have engineered yeast genomic DNA to construct a set of Strains producing various relative amounts of yeast NADPH-P450 reductase (Yred) and human cytochrome b5 (Hb5). Expression of cDNAs encoding human P450 1A1, 1A2, 3A4, 19A and mouse P450 1A1 in the different oxido-reduction backgrounds thus constituted were achieved after Strain Transformation by plasmid-based P450-encoding expression cassettes. The results indicate that the level of Yred strongly affects all activities tested. In contrast, the amount of Hb5 affects activities in a manner that is dependent both on the P450 isoform considered and the Yred level. In a Strain containing optimized amounts of Hb5 and Yred, human P450 3A4-specific testosterone-6 beta-hydroxylase activity can be enhanced as much as 73-fold in comparison with the activity observed in a wild-type Strain. Bioconversion of sterols or xenobiotics was easily achieved in vivo using this new co-expression system.
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enhanced in vivo monooxygenase activities of mammalian p450s in engineered yeast cells producing high levels of nadph p450 reductase and human cytochrome b5
Gene, 1993Co-Authors: Gilles Truan, Christophe Cullin, Philippe Reisdorf, Philippe Urban, Denis PomponAbstract:Abstract We have engineered yeast genomic DNA to construct a set of Strains producing various relative amounts of yeast NADPH-P450 reductase (Yred) and human cytochrome b5 (Hb5). Expression of cDNAs encoding human P450 1A1, 1A2, 3A4, 19A and mouse P450 1A1 in the different oxido-reduction backgrounds thus constituted were achieved after Strain Transformation by plasmid-based P450-encoding expression cassettes. The results indicate that the level of Yred strongly affects all activities tested. In contrast, the amount of Hb5 affects activities in a manner that is dependent both on the P450 isoform considered and the Yred level. In a Strain containing optimized amounts of Hb5 and Yred, human P450 3A4-specific testosterone-6β-hydroxylase activity can be enhanced as much as 73-fold in comparison with the activity observed in a wild-type Strain. Bioconversion of sterols or xenobiotics was easily achieved in vivo using this new co-expression system.