The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Bruce David Johnson - One of the best experts on this subject based on the ideXlab platform.
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a possible role for systemic hypoxia in the Reactive Component of pulmonary hypertension in heart failure
Journal of Cardiac Failure, 2013Co-Authors: Bryan J Taylor, Cesar R Mojica, Thomas P Olson, Paul R Woods, Robert P Frantz, Bruce David JohnsonAbstract:Abstract Background The mechanisms underlying the Reactive Component of pulmonary hypertension (PH) in heart failure (HF) are unclear. We examined whether resting systemic oxygen levels are related to pulmonary hemodynamics in HF. Methods and Results Thirty-nine HF patients underwent right heart catheterization. Subsequently, patients were classified as having: 1) no PH (n = 12); 2) passive PH (n = 10); or 3) Reactive PH (n = 17). Blood was drawn from the radial and pulmonary arteries for the determination of PaO 2 , SaO 2 , PvO 2 , SvO 2 , and vasoactive neurohormones. PaO 2 and PvO 2 were lower in Reactive PH versus no PH and passive PH patients (65.3 ± 8.6 vs 78.3 ± 11.4 mm Hg and 74.5 ± 14.0 mm Hg; 29.2 ± 4.1 vs 36.2 ± 2.8 mm Hg and 33.4 ± 2.3 mm Hg; P 2 and SvO 2 were lower in Reactive PH versus no PH patients (93 ± 3% vs 96 ± 3%; 51 ± 11% vs 68 ± 4%; P 2 , PvO 2 , SaO 2 , and SvO 2 in the Reactive PH patients only ( r ≤ −0.557; P 2 , PvO 2 , SvO 2 ( r ≤ −0.495), and TPG ( r = 0.662; P Conclusions Systemic hypoxia may play a role in the Reactive Component of PH in HF, potentially via a hypoxia-induced increase in endothelial release of the vasoconstrictor endothelin-1.
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Basic Science and Experimental Studies A Possible Role for Systemic Hypoxia in the Reactive Component of Pulmonary Hypertension in Heart Failure
2013Co-Authors: Bryan J Taylor, Cesar R Mojica, Thomas P Olson, Paul R Woods, Robert P Frantz, Bruce David JohnsonAbstract:Background: The mechanisms underlying the Reactive Component of pulmonary hypertension (PH) in heart failure (HF) are unclear. We examined whether resting systemic oxygen levels are related to pulmonary hemodynamics in HF. Methods and Results: Thirty-nine HF patients underwent right heart catheterization. Subsequently, patients were classified as having: 1) no PH (n 5 12); 2) passive PH (n 5 10); or 3) Reactive PH (n 5 17). Blood was drawn from the radial and pulmonary arteries for the determination of PaO2, SaO2, PvO2, SvO2, and vasoactive neurohormones. PaO2 and PvO2 were lower in Reactive PH versus no PH and passive PH patients (65.3 6 8.6 vs 78.3 6 11.4 mm Hg and 74.5 6 14.0 mm Hg; 29.2 6 4.1 vs 36.2 6 2.8 mm Hg and 33.4 6 2.3 mm Hg; P ! .05). SaO2 and SvO2 were lower in Reactive PH versus no PH patients (93 6 3% vs 96 6 3%; 51 6 11% vs 68 6 4%; P ! .05), but not different versus passive PH patients. The transpulmonary pressure gradient (TPG) was inversely related to PaO2, PvO2, SaO2, and SvO2 in the Reactive PH patients only (r # � 0.557; P ! .05). Similarly, plasma endothelin-1 correlated with PaO2, PvO2, SvO2 (r # � 0.495), and TPG (r 5 0.662; P ! .05) in Reactive PH patients only. Conclusions: Systemic hypoxia may play a role in the Reactive Component of PH in HF, potentially via a hypoxia-induced increase in endothelial release of the vasoconstrictor endothelin-1. (J Cardiac Fail 2013;19:50e59)
H A Toliyat - One of the best experts on this subject based on the ideXlab platform.
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design and rating comparisons of pwm voltage source rectifiers and active power filters for ac drives with unity power factor
IEEE Transactions on Power Electronics, 2005Co-Authors: Sangshin Kwak, H A ToliyatAbstract:Given terminal constraints of unity power factor in ac drive applications, two ac drives are possible: one with a pulse-width modulation voltage source rectifier (PWM-VSR) and the other using a diode rectifier and an active power filter. Despite numerous publications for the two drives, the features and advantages between them have not been clearly explained. This paper presents a theoretical analysis and systematic comparison between the two drive topologies. Converter kVA ratings, dc-link voltage requirements, switch ratings, semiconductor losses, and Reactive Component designs are considered for the evaluations.
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Design and performance comparisons of two multidrive systems with unity power factor
IEEE Transactions on Power Delivery, 2005Co-Authors: Sangshin Kwak, H A ToliyatAbstract:From economical aspects, the multidrive systems are a promising application area for the converters, where the cost and size of the converters are shared by multiple inverter-motors. Given terminal constraints of unity power factor in grid line and independent multiple motor controls in output ports, two multidrive topologies are possible: one with single PWM-VSR feeding inverters through the common dc bus, and the other using a diode rectifier and an active power filter with its own load. Despite several publications for two systems, the features and advantages of the two systems have not been clearly explained. This paper, in detail, presents the theoretical analyses and systematic comparisons of the two multidrive topologies, from converter kilovolt-ampere ratings, dc-link voltage requirements, switch ratings, semiconductor losses, and Reactive Component designs point of views.
Victor M. Prida - One of the best experts on this subject based on the ideXlab platform.
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Frequency dependence of hysteretic magnetoimpedance in CoFeMoSiB amorphous ribbons
Journal of Magnetism and Magnetic Materials, 2000Co-Authors: M. Tejedor, Blanca Hernando, Victor M. Prida, M. L. Sánchez, Galina V. Kurlyandskaya, D. Garcia, Manuel VázquezAbstract:Abstract The hysteretic behaviour of the resistive and Reactive Components of the complex impedance at different frequencies in Co-based ribbons is presented. Sensitivities of the order of 1.2%/Am −1 at 70 kHz for the Reactive Component of the MI and 0.63%/Am −1 at 500 kHz for the resistive one were attained in the field range of 80–560 Am −1 . The maximum relative ratio of MI was reached at 120 kHz with a sensitivity of 0.41%/Am −1 .
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Magnetic field and low frequency dependence of impedance Reactive Component in nanocrystalline Fe73.5Cu1Nb3Si16.5B6 ribbons
Journal of Magnetism and Magnetic Materials, 1999Co-Authors: M. Tejedor, Blanca Hernando, María Luisa Fernández Sánchez, Victor M. PridaAbstract:Abstract The behaviour of the Reactive Component of impedance with the applied magnetic field and frequencies up to 120 kHz has been studied in Fe 73.5 Cu 1 Nb 3 Si 16.5 B 6 ribbons, after annealing at temperatures in the range between 400°C and 600°C. Reactive ratios of around 58% and sensitivities to the applied field of 40%/Oe were obtained.
Petra Pötschke - One of the best experts on this subject based on the ideXlab platform.
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The Localization Behavior of Different CNTs in PC/SAN Blends Containing a Reactive Component
Molecules (Basel Switzerland), 2021Co-Authors: Marén Gültner, Regine Boldt, Petr Formanek, Dieter Fischer, Frank Simon, Petra PötschkeAbstract:Co-continuous blend systems of polycarbonate (PC), poly(styrene-co-acrylonitrile) (SAN), commercial non-functionalized multi-walled carbon nanotubes (MWCNTs) or various types of commercial and laboratory functionalized single-walled carbon nanotubes (SWCNTs), and a Reactive Component (RC, N-phenylmaleimide styrene maleic anhydride copolymer) were melt compounded in one step in a microcompounder. The blend system is immiscible, while the RC is miscible with SAN and contains maleic anhydride groups that have the potential to Reactively couple with functional groups on the surface of the nanotubes. The influence of the RC on the localization of MWCNTs and SWCNTs (0.5 wt. %) was investigated by transmission electron microscopy (TEM) and energy-filtered TEM. In PC/SAN blends without RC, MWCNTs are localized in the PC Component. In contrast, in PC/SAN-RC, the MWCNTs localize in the SAN-RC Component, depending on the RC concentration. By adjusting the MWCNT/RC ratio, the localization of the MWCNTs can be tuned. The SWCNTs behave differently compared to the MWCNTs in PC/SAN-RC blends and their localization occurs either only in the PC or in both blend Components, depending on the type of the SWCNTs. CNT defect concentration and surface functionalities seem to be responsible for the localization differences.
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tuning the localization of functionalized mwcnts in san pc blends by a Reactive Component
Composites Science and Technology, 2011Co-Authors: Marén Gültner, Andreas Göldel, Petra PötschkeAbstract:Abstract The influence of the Reactive Component (N-phenylmaleimide styrene maleic anhydride) on the blend morphology, the localization of functionalized multiwalled carbon nanotubes (MWCNTs), and the electrical resistivity of MWCNT filled blend systems of polycarbonate (PC) and poly(styrene-co-acrylonitrile) (SAN) was investigated. SAN, PC, amino-functionalized MWCNTs (Nanocyl™ NC3152) and the Reactive Component (RC) were melt mixed in a DSM Xplore microcompounder using different mixing sequences. The RC containing maleic anhydride (MA) groups is miscible with SAN and is assumed to act as linking agent to the functionalized MWCNTs. The morphology of the SAN/PC blends was studied depending on the concentration of the RC. Thereby co-continuous morphologies were found for all blends with 40 wt.% SAN and 60 wt.% PC. In all nonmodified blends the MWCNTs were localized within the PC phase. After the addition of RC the MWCNTs migrated completely into the miscible SAN–RC phase. Consequently, the electrical resistivities of the blends changed in dependence on the localization. Whereas the SAN/PC/MWCNT blends showed low electrical resistivity values, much higher values were found for SAN–RC/PC/MWCNT blends. This was assigned to a coupling or strong interaction of MA groups to the nanotubes disturbing electrical contacts and percolation between them. The occurrence of the MWCNT migration from PC towards SAN was found to be dependent on the concentrations of RC and MWCNTs. By adapting that ratio and the mixing strategy, the localization of the carbon nanotubes in the blend phases can be tuned. The investigations indicated that MWCNTs once coupled with the RC remain in the SAN–RC phase. Thus, a chemical reaction or strong interactions seem to be the driving forces for localization of the MWCNTs in the SAN–RC blend phase.
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Tuning the localization of functionalized MWCNTs in SAN/PC blends by a Reactive Component
Composites Science and Technology, 2011Co-Authors: Marén Gültner, Andreas Göldel, Petra PötschkeAbstract:Abstract The influence of the Reactive Component (N-phenylmaleimide styrene maleic anhydride) on the blend morphology, the localization of functionalized multiwalled carbon nanotubes (MWCNTs), and the electrical resistivity of MWCNT filled blend systems of polycarbonate (PC) and poly(styrene-co-acrylonitrile) (SAN) was investigated. SAN, PC, amino-functionalized MWCNTs (Nanocyl™ NC3152) and the Reactive Component (RC) were melt mixed in a DSM Xplore microcompounder using different mixing sequences. The RC containing maleic anhydride (MA) groups is miscible with SAN and is assumed to act as linking agent to the functionalized MWCNTs. The morphology of the SAN/PC blends was studied depending on the concentration of the RC. Thereby co-continuous morphologies were found for all blends with 40 wt.% SAN and 60 wt.% PC. In all nonmodified blends the MWCNTs were localized within the PC phase. After the addition of RC the MWCNTs migrated completely into the miscible SAN–RC phase. Consequently, the electrical resistivities of the blends changed in dependence on the localization. Whereas the SAN/PC/MWCNT blends showed low electrical resistivity values, much higher values were found for SAN–RC/PC/MWCNT blends. This was assigned to a coupling or strong interaction of MA groups to the nanotubes disturbing electrical contacts and percolation between them. The occurrence of the MWCNT migration from PC towards SAN was found to be dependent on the concentrations of RC and MWCNTs. By adapting that ratio and the mixing strategy, the localization of the carbon nanotubes in the blend phases can be tuned. The investigations indicated that MWCNTs once coupled with the RC remain in the SAN–RC phase. Thus, a chemical reaction or strong interactions seem to be the driving forces for localization of the MWCNTs in the SAN–RC blend phase.
M. Tejedor - One of the best experts on this subject based on the ideXlab platform.
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Frequency dependence of hysteretic magnetoimpedance in CoFeMoSiB amorphous ribbons
Journal of Magnetism and Magnetic Materials, 2000Co-Authors: M. Tejedor, Blanca Hernando, Victor M. Prida, M. L. Sánchez, Galina V. Kurlyandskaya, D. Garcia, Manuel VázquezAbstract:Abstract The hysteretic behaviour of the resistive and Reactive Components of the complex impedance at different frequencies in Co-based ribbons is presented. Sensitivities of the order of 1.2%/Am −1 at 70 kHz for the Reactive Component of the MI and 0.63%/Am −1 at 500 kHz for the resistive one were attained in the field range of 80–560 Am −1 . The maximum relative ratio of MI was reached at 120 kHz with a sensitivity of 0.41%/Am −1 .
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Magnetic field and low frequency dependence of impedance Reactive Component in nanocrystalline Fe73.5Cu1Nb3Si16.5B6 ribbons
Journal of Magnetism and Magnetic Materials, 1999Co-Authors: M. Tejedor, Blanca Hernando, María Luisa Fernández Sánchez, Victor M. PridaAbstract:Abstract The behaviour of the Reactive Component of impedance with the applied magnetic field and frequencies up to 120 kHz has been studied in Fe 73.5 Cu 1 Nb 3 Si 16.5 B 6 ribbons, after annealing at temperatures in the range between 400°C and 600°C. Reactive ratios of around 58% and sensitivities to the applied field of 40%/Oe were obtained.
