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Sample records for active npc converter

  1. A New PWM Strategy for Grid-Connected Half-Bridge Active NPC Converters With Losses Distribution Balancing Mechanism

    DEFF Research Database (Denmark)

    Lin, Ma; Kerekes, Tamas; Rodriguez, Pedro

    2015-01-01

    Photovoltaic systems technological development is driven by the request for higher efficiency and safety. These concerns influence also the choice of the power converter stage. Several topologies have been proposed and many of them are available commercially. Among them, the neutral point clamped....... By using the active NPC (ANPC) topology, where the clamping diodes are replaced by bidirectional switches, the power losses distribution problem is alleviated. The modulation strategy is a key issue for losses distribution in this topology. In this paper, two known strategies are discussed and a new PWM...

  2. Open-switch fault detection method of an NPC converter for wind turbine systems

    DEFF Research Database (Denmark)

    Lee, June-Seok; Lee, Kyo-Beum; Blaabjerg, Frede

    2013-01-01

    In wind turbine generation (WTG) systems, the neutral-point-clamped (NPC) topology is widely used as the part of a back-to-back converter since the three-level NPC topology has more advantages than the conventional two-level inverter especially for high power. There are twelve switches in the NPC...... topology and an open-switch fault of the NPC converter leads to current distortion and the torque ripple in the system. Furthermore, WTG systems can breakdown in the worst case by this ripple. To improve the reliability of WTG systems, an open-switch fault detection method is required. The open-switch...... detection method of the NPC converter is different from that of the NPC inverter due to the different current paths of the NPC converter. This paper proposes the open-switch fault detection method of the NPC converter connected the permanent-magnet synchronous generator (PMSG). Moreover, the open-switch...

  3. Development of modulation strategies for NPC converter addressing DC link voltage balancing and CMV reduction

    DEFF Research Database (Denmark)

    Boian, D.; Biris, C.; Teodorescu, Remus

    2012-01-01

    in insulation breakdown and bearing failures. By the use of this type of converters, both Electromagnetic Interference (EMI) and harmonic distortions are improved. This paper proposes two modulation strategies for Three Level Neutral Point Clamped Converter (3L-NPC). The main focus of these modulation...

  4. Optimal design of NPC and Active-NPC transformerless PV inverters

    DEFF Research Database (Denmark)

    Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

    2012-01-01

    Targeting at a cost-effective deployment of grid-connected PhotoVoltaic (PV) systems, this paper presents a new methodology for the optimal design of transformerless PV inverters, which are based on the Neutral Point Clamped (NPC) and the Active-Neutral Point Clamped (ANPC) topologies. The design...... optimization results demonstrate that a different set of optimal values of the PV inverter switching frequency and output filter components are derived for the NPC and ANPC topologies, respectively, as well as for each of the PV inverter installation sites under study. The NPC and ANPC PV inverter structures......, which are derived using the proposed design optimization methodology exhibit lower Levelized Cost Of generated Electricity (LCOE) and manufacturing cost and they are simultaneously capable to inject more energy into the electric grid than the corresponding non-optimized PV inverters. Thus, the proposed...

  5. A New Backward Euler Stabilized Optimum Controller for NPC Back-to-Back Five Level Converters

    Directory of Open Access Journals (Sweden)

    Miguel Chaves

    2017-05-01

    Full Text Available This paper presents a backward Euler stabilized-based control strategy applied to a neutral point clamped (NPC back-to-back connected five level converters. A generalized method is used to obtain the back-to-back NPC converter system model. The backward Euler stabilized-based control strategy uses one set of calculations to compute the optimum voltage vector needed to reach the references and to balance the voltage of the DC-bus capacitors. The output voltage vector is selected using a modified cost functional that includes variable tracking errors in the functional weights, whereas in classic approaches, the weights are considered constant. The proposed modified cost functional enables AC current tracking and DC-bus voltage balancing in a wide range of operating conditions. The paper main contributions are: (i a backward Euler stabilized-based control strategy applied to a double, back-to-back connected, five level NPC converter; (ii the use of cost functional weight varying as a function of the controlled variable tracking errors to enforce the controlled variables and to balance the DC capacitor voltages; and (iii the demonstration of system feasibility for this type of converter topology and control strategy, ensuring a high enough computational efficiency and extending the modulation index from 0.6 to 0.93. Experimental results are presented using a prototype of a five level NPC back-to-back converter.

  6. Open-Switch Fault Detection Method of a Back-to-Back Converter Using NPC Topology for Wind Turbine Systems

    DEFF Research Database (Denmark)

    Lee, June-Seok; Lee, Kyo_Beum; Blaabjerg, Frede

    2015-01-01

    In wind turbine generation (WTG) systems, a back-to-back converter with a neutral-point-clamped (NPC) topology is widely used because this topology has more advantages than a conventional two-level topology, particularly when operating at high power. There are 12 switches in the NPC topology....... An open-switch fault in the NPC rectifier of the back-to-back converter leads to the distortion of the input current and torque vibration in the system. Additionally, an open-switch fault in the NPC inverter of the back-to-back converter causes the distortion of the output current. Furthermore, the WTG...... system can break down in the worst case scenario. To improve the reliability of WTG systems, an open-switch fault detection method for back-to-back converters using the NPC topology is required. This study analyzes effects of inner and outer open-switch faults of the NPC rectifier and inverter...

  7. A SVPWM based on fluctuate capacitor voltage in 3L-NPC back-to-back converter applied to wind energy

    DEFF Research Database (Denmark)

    Chen, Quan; Wang, Qunjing; Chen, Zhe

    2014-01-01

    ' voltage, will cause variations of the voltage vector and the dwell time distribution in the synthesizing algorithm. In this paper a novel space vector PWM (SVPWM) for back-to-back 3L-NPC converter when unbalanced neutral point potential occurring is proposed. An error factor based on the difference...... between the fluctuate voltage of upper and lower capacitors is extracted. Based on this error factor the duty-time of every active voltage vector is calculated. In order to validate the model and the control strategy proposed in this paper, a 2MW 3L-NPC converter used in wind energy has been simulated....

  8. Optimized Pulse Width Modulation for transformerless active-NPC inverters

    DEFF Research Database (Denmark)

    Achilladelis, Nikolaos; Koutroulis, Eftichios; Blaabjerg, Frede

    2014-01-01

    their power semiconductors. In this paper, a new modulation technique is proposed for optimally controlling the power switches employed in transformerless Active-NPC inverters. The design results demonstrate that compared to the existing PWM strategies, using the proposed method results in lower total power......The transformerless DC/AC inverter topologies are employed in Photovoltaic systems in order to improve the power conversion efficiency, power density and cost. The Active-Neutral Point Clamped (Active-NPC) transformerless inverters have the advantage of achieving better thermal balance among...

  9. A hierarchical model predictive voltage control for NPC/H-bridge converters with a reduced computational burden

    DEFF Research Database (Denmark)

    Gong, Zheng; Dai, Peng; Wu, Xiaojie

    2017-01-01

    In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS-MPC) stra......In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS......-MPC) strategy is not practical for multilevel converters due to their substantial calculation requirements, especially under high number of voltage levels. To solve this problem, a hierarchical model predictive voltage control (HMPVC) strategy with referring to the implementation of g-h coordinate space vector...... calculation is significantly reduced and the advantages of the conventional FCS-MPC strategy are reserved. In addition, a HMPVC-based field oriented control scheme is applied to a drive system with the NPC/H-Bridge converter. Both steady-state and transient performances are evaluated by simulations...

  10. A High Performance Power Supply based on a Four-Leg Three-Level NPC Converter for Non-linear and Unbalanced Systems

    OpenAIRE

    Rojas Lobos, Felix Eduardo

    2016-01-01

    Throughout this Dissertation, the reader will find a comprehensive review and discussion about the state of the art and future perspectives of VSI implemented in four-wire applications. The three-dimensional Space Vector Modulation problem for this kind of converters is extensively discussed and a simple modulation algorithm for a three-level four-leg NPC converter is proposed and successfully validated in an experimental rig. Afterwards, the proposed modulation technique is implemented in an...

  11. Multiple low frequency dual reference PWM control of a grid connected photovoltaic three phase NPC inverter with DC/DC boost converter

    Directory of Open Access Journals (Sweden)

    Mechouma Rabiaa

    2014-01-01

    Full Text Available In recent years, power demand of industrial applications has increased significantly reaching some megawatts. The use of multilevel converters for applications of medium and high powers is proposed as a solution to drawback semiconductor technology. A multilevel converter not only achieves high power ratings, but also enables the use of renewable energy sources. Renewable energy sources such as photovoltaic can be easily interfaced to a multilevel converter system for a high power application. This paper presents the simulation study in Matlab/Simulink of a grid connected photovoltaic three phase Neutral Point Clamped (NPC inverter with DC/DC boost converter for constant and variable solar radiation.

  12. The mitochondrion interfering compound NPC-26 exerts potent anti-pancreatic cancer cell activity in vitro and in vivo.

    Science.gov (United States)

    Dong, Yang-Yang; Zhuang, Yi-Huang; Cai, Wen-Jie; Liu, Yan; Zou, Wen-Bing

    2016-11-01

    The development of novel anti-pancreatic cancer agents is extremely important. Here, we investigated the anti-pancreatic cancer activity by NPC-26, a novel mitochondrion interfering compound. We showed that NPC-26 was anti-proliferative and cytotoxic to human pancreatic cancer cells, possibly via inducing caspase-9-dependent cell apoptosis. Pharmacological inhibition or shRNA-mediated silence of caspase-9 attenuated NPC-26-induced pancreatic cancer cell death and apoptosis. Further, NPC-26 treatment led to mitochondrial permeability transition pore (mPTP) opening in the cancer cells, which was evidenced by mitochondrial depolarization, ANT-1(adenine nucleotide translocator-1)-Cyp-D (cyclophilin-D) association and oxidative phosphorylation disturbance. mPTP blockers (cyclosporin and sanglifehrin A) or shRNA-mediated knockdown of key mPTP components (Cyp-D and ANT-1) dramatically attenuated NPC-26-induced pancreatic cancer cell apoptosis. Importantly, we showed that NPC-26, at a low concentration, potentiated gemcitabine-induced mPTP opening and subsequent pancreatic cancer cell apoptosis. In vivo, NPC-26 intraperitoneal injection significantly suppressed the growth of PANC-1 xenograft tumors in nude mice. Meanwhile, NPC-26 sensitized gemcitabine-mediated anti-pancreatic cancer activity in vivo. In summary, the results of this study suggest that NPC-26, alone or together with gemcitabine, potently inhibits pancreatic cancer cells possibly via disrupting mitochondrion.

  13. All-trans retinoic acid-triggered antimicrobial activity against Mycobacterium tuberculosis is dependent on NPC2.

    Science.gov (United States)

    Wheelwright, Matthew; Kim, Elliot W; Inkeles, Megan S; De Leon, Avelino; Pellegrini, Matteo; Krutzik, Stephan R; Liu, Philip T

    2014-03-01

    A role for vitamin A in host defense against Mycobacterium tuberculosis has been suggested through epidemiological and in vitro studies; however, the mechanism is unclear. In this study, we demonstrate that vitamin A-triggered antimicrobial activity against M. tuberculosis requires expression of NPC2. Comparison of monocytes stimulated with all-trans retinoic acid (ATRA) or 1,25-dihydroxyvitamin D3 (1,25D3), the biologically active forms of vitamin A and vitamin D, respectively, indicates that ATRA and 1,25D3 induce mechanistically distinct antimicrobial activities. Stimulation of primary human monocytes with ATRA did not result in expression of the antimicrobial peptide cathelicidin, which is required for 1,25D3 antimicrobial activity. In contrast, ATRA triggered a reduction in the total cellular cholesterol concentration, whereas 1,25D3 did not. Blocking ATRA-induced cellular cholesterol reduction inhibits antimicrobial activity as well. Bioinformatic analysis of ATRA- and 1,25D3-induced gene profiles suggests that NPC2 is a key gene in ATRA-induced cholesterol regulation. Knockdown experiments demonstrate that ATRA-mediated decrease in total cellular cholesterol content and increase in lysosomal acidification are both dependent upon expression of NPC2. Expression of NPC2 was lower in caseous tuberculosis granulomas and M. tuberculosis-infected monocytes compared with normal lung and uninfected cells, respectively. Loss of NPC2 expression ablated ATRA-induced antimicrobial activity. Taken together, these results suggest that the vitamin A-mediated antimicrobial mechanism against M. tuberculosis requires NPC2-dependent expression and function, indicating a key role for cellular cholesterol regulation in the innate immune response.

  14. The Impact of Power Switching Devices on the Thermal Performance of a 10 MW Wind Power NPC Converter

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2012-01-01

    of significant deviation in the packaging structure, electrical characteristics, as well as thermal impedance, these available power switching devices may have various thermal cycling behaviors, which will lead to converter solutions with very different cost, size and reliability performance. As a result......, this paper aimed to investigate the thermal related characteristics of some important power switching devices. Their impact on the thermal cycling of a 10 MW three-level Neutral-Point-Clamped wind power converter is then evaluated under various operating conditions; the main focus will be on the grid......Power semiconductor switching devices play an important role in the performance of high power wind energy generation systems. The state-of-the-art device choices in the wind power application as reported in the industry include IGBT modules, IGBT press-pack and IGCT press-pack. Because...

  15. Assessment of plasma chitotriosidase activity, CCL18/PARC concentration and NP-C suspicion index in the diagnosis of Niemann-Pick disease type C: a prospective observational study.

    Science.gov (United States)

    De Castro-Orós, Isabel; Irún, Pilar; Cebolla, Jorge Javier; Rodriguez-Sureda, Victor; Mallén, Miguel; Pueyo, María Jesús; Mozas, Pilar; Dominguez, Carmen; Pocoví, Miguel

    2017-02-21

    Niemann-Pick disease type C (NP-C) is a rare, autosomal recessive neurodegenerative disease caused by mutations in either the NPC1 or NPC2 genes. The diagnosis of NP-C remains challenging due to the non-specific, heterogeneous nature of signs/symptoms. This study assessed the utility of plasma chitotriosidase (ChT) and Chemokine (C-C motif) ligand 18 (CCL18)/pulmonary and activation-regulated chemokine (PARC) in conjunction with the NP-C suspicion index (NP-C SI) for guiding confirmatory laboratory testing in patients with suspected NP-C. In a prospective observational cohort study, incorporating a retrospective determination of NP-C SI scores, two different diagnostic approaches were applied in two separate groups of unrelated patients from 51 Spanish medical centers (n = 118 in both groups). From Jan 2010 to Apr 2012 (Period 1), patients with ≥2 clinical signs/symptoms of NP-C were considered 'suspected NP-C' cases, and NPC1/NPC2 sequencing, plasma chitotriosidase (ChT), CCL18/PARC and sphingomyelinase levels were assessed. Based on findings in Period 1, plasma ChT and CCL18/PARC, and NP-C SI prediction scores were determined in a second group of patients between May 2012 and Apr 2014 (Period 2), and NPC1 and NPC2 were sequenced only in those with elevated ChT and/or elevated CCL18/PARC and/or NP-C SI ≥70. Filipin staining and 7-ketocholesterol (7-KC) measurements were performed in all patients with NP-C gene mutations, where possible. In total across Periods 1 and 2, 10/236 (4%) patients had a confirmed diagnosis o NP-C based on gene sequencing (5/118 [4.2%] in each Period): all of these patients had two causal NPC1 mutations. Single mutant NPC1 alleles were detected in 8/236 (3%) patients, overall. Positive filipin staining results comprised three classical and five variant biochemical phenotypes. No NPC2 mutations were detected. All patients with NPC1 mutations had high ChT activity, high CCL18/PARC concentrations and/or NP-C SI scores ≥70. Plasma 7

  16. Model Predictive Controlled Active NPC Inverter for Voltage Stress Balancing Among the Semiconductor Power Switches

    Science.gov (United States)

    Parvez Akter, Md.; Dah-Chuan Lu, Dylan

    2017-07-01

    This paper presents a model predictive controlled three-level three-phase active neutral-point-clamped (ANPC) inverter for distributing the voltage stress among the semiconductor power switches as well as balancing the neutral-point voltage. The model predictive control (MPC) concept uses the discrete variables and effectively operates the ANPC inverter by avoiding any linear controller or modulation techniques. A 4.0 kW three-level three-phase ANPC inverter is developed in the MATLAB/Simulink environment to verify the effectiveness of the proposed MPC scheme. The results confirm that the proposed model predictive controlled ANPC inverter equally distributes the voltage across all the semiconductor power switches and provides lowest THD (0.99%) compared with the traditional NPC inverter. Moreover, the neutral-point voltage balancing is accurately maintained by the proposed MPC algorithm. Furthermore, this MPC concept shows the robustness capability against the parameter uncertainties of the system which is also analyzed by MATLAB/Simulink.

  17. The PWM strategies of grid-connected distributed generation active NPC inverters

    DEFF Research Database (Denmark)

    Ma, Lin; Xinmin, Jin; Kerekes, Tamas

    2009-01-01

    The Neutral Point Clamped topology due to high efficiency, low leakage current and EMI, its integration is widely used in the distributed generation (DG) systems. However the main disadvantage of the NPC inverter is given by an unequal distribution of the losses in the semiconductor devices, which...

  18. Power density investigations for the large wind turbines' grid-side press-pack IGBT 3L-NPC-VSCs

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2012-01-01

    Power density is the important design criterion in wind turbine converter design provided that satisfactory converter performance is guaranteed. In order to assess a converter in terms of power density, which is dependent on converter electrical and thermal behaviors, converter electro-thermal...... models are required to be derived, implemented, and utilized. In this study, employed as a grid-side medium voltage full-scale voltage source converters (VSCs) in a multi-MW wind turbine, press-pack IGBT three-level neutral-point-clamped VSC (3L-NPC-VSC), 3L active NPC-VSC (3L-ANPC-VSC), and 3L neutral......-point-piloted VSC (3L-NPP-VSC) are characterized in terms of converter operating principles, physical structure, power loss, and DC bus capacitor size for establishing the basis for converter electro-thermal modeling. Via the practical implementations of the converter electro-thermal models in a computation...

  19. Analyze and Improve Lifetime in 3L-NPC Inverter from Power Cycle and Thermal Balance

    DEFF Research Database (Denmark)

    Chen, Quan; Chen, Zhe; Wang, Qunjing

    2014-01-01

    Three-level Neutral-point-clamped (3L-NPC) topology is becoming a realistic alternative to the conventional one in high-voltage and high-power application. Studies show that the power cycling mean time to failure (MTTF) of the semiconductor bond wire in 3L-NPC inverter system may be very short...... and load voltage is applied to reduce power cycle and switching losses. And then, three-level active neutral point-clamped topology is taken into account to wake the most thermo stressed device. In order to validate the improve lifetime method in this paper, a 2MW 3L-NPC converter used in wind energy has...... under some common conditions. Firstly, this paper shows the impact of some key parameters on power electronic system lifetime according the analysis of semiconductor failure mechanism. Secondly, a switching frequency reduction method based on the position relationship between the flowing current...

  20. NPC2 regulates biliary cholesterol secretion via stimulation of ABCG5/G8-mediated cholesterol transport.

    Science.gov (United States)

    Yamanashi, Yoshihide; Takada, Tappei; Yoshikado, Takashi; Shoda, Jun-Ichi; Suzuki, Hiroshi

    2011-05-01

    Biliary cholesterol secretion helps maintain cholesterol homeostasis; it is regulated by the cholesterol exporter adenosine triphosphate-binding cassettes G5 and G8 (ABCG5/G8) and the cholesterol importer Niemann-Pick C1-like 1 (NPC1L1). We studied another putative regulator of cholesterol secretion into bile, Niemann-Pick C2 (NPC2)--a cholesterol-binding protein secreted by the biliary system--and determined its effects on transporter-mediated biliary secretion of cholesterol. Mice with hepatic knockdown of Npc2 or that overexpressed NPC2 were created using adenovirus-mediated gene transfer; biliary lipids were characterized. The effects of secreted NPC2 on cholesterol transporter activity were examined in vitro using cells that overexpressed ABCG5/G8 or NPC1L1. Studies of mice with altered hepatic expression of NPC2 revealed that this expression positively regulates the biliary secretion of cholesterol, supported by the correlation between levels of NPC2 protein and cholesterol in human bile. In vitro analysis showed that secreted NPC2 stimulated ABCG5/G8-mediated cholesterol efflux but not NPC1L1-mediated cholesterol uptake. Consistent with these observations, no significant changes in biliary cholesterol secretion were observed on hepatic overexpression of NPC2 in ABCG5/G8-null mice, indicating that NPC2 requires ABCG5/G8 to stimulate cholesterol secretion. Analyses of NPC2 mutants showed that the stimulatory effect of biliary NPC2 was independent of the function of lysosomal NPC2 as a regulator of intracellular cholesterol trafficking. NPC2 is a positive regulator of biliary cholesterol secretion via stimulation of ABCG5/G8-mediated cholesterol transport. Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.

  1. New active load voltage clamp for HF-link converters

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path...

  2. Oxygen reduction in acid media: influence of the heat treatment on the FeNPc(1–20 isomer mixture impregnated on carbon blacks and active charcoals

    NARCIS (Netherlands)

    Biloul, A.; Coowar, F.; Contamin, O.; Scarbeck, G.; Savy, M.; van den Ham, D.; Riga, J.; Verbist, J.J.

    1992-01-01

    Oxygen reduction with the aid of a number of FeNPc(1–2) impregnated carbon supports in sulphuric acid solutions has been investigated. Loading of the carbon samples amounted to about 10 wt.%. After a 10 day stay in the aerated solutions the samples were investigated with rotating disk electrode and

  3. Boost Converter with Active Snubber Network

    Directory of Open Access Journals (Sweden)

    HIMMELSTOSS, F. A.

    2017-02-01

    Full Text Available A new concept for reducing the losses in a boost converter is described. With the help of an auxiliary switch and a resonant circuit, zero-voltage switching at turn-off and zero-current switching during turn-on are achieved. The modes of the circuit are shown in detail. The energy recovery of the turn-off is analyzed and the recovered energy is calculated; an optimized switching concept therefore is described. The influence of the parasitic capacity of the switch is discussed. Dimensioning hints for the converter and the design of the recuperation circuit are given. A bread-boarded design shows the functional efficiency of the concept.

  4. Converting Poultry Litter into Activated Carbon

    Science.gov (United States)

    Disposal of animal manure is one of the biggest problems facing agriculture today. Now new technology has been designed to covert manure into environmentally friendly and highly valued activated carbon. When pelletized and activated under specific conditions, the litter becomes a highly porous mat...

  5. New active load voltage clamp for HF-link converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, M.A.E.

    2005-07-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path during malfunctions of the secondary bidirectional bridge. The feasibility of the approach is shown on audio power amplifier prototype. New integrated magnetics design is presented that incorporates both the main power and auxiliary transformer on the same magnetic core. (au)

  6. Oxygen activity measurements in simulated converter matte

    CSIR Research Space (South Africa)

    Tshilombo, KG

    2007-01-01

    Full Text Available African Institute of Mining and Metallurgy VOLUME 107 REFEREED PAPER FEBRUARY 2007 Background Expected relationship between oxygen activity and iron content of matte The ideas tested in this work are that the activity of oxygen, as established.... © The Southern African Institute of Mining and Metallurgy, 2007. SA ISSN 0038–223X/3.00 + 0.00. This paper was first published at the SAIMM Conference, Platinum Surges Ahead, 8–12 October 2006. T r a n s a c t i o n P a p e r L123 Oxygen...

  7. Ezetimibe-sensitive cholesterol uptake by NPC1L1 protein does not require endocytosis.

    Science.gov (United States)

    Johnson, Tory A; Pfeffer, Suzanne R

    2016-06-01

    Human NPC1L1 protein mediates cholesterol absorption in the intestine and liver and is the target of the drug ezetimibe, which is used to treat hypercholesterolemia. Previous studies concluded that NPC1L1-GFP protein trafficking is regulated by cholesterol binding and that ezetimibe blocks NPC1L1-GFP function by inhibiting its endocytosis. We used cell surface biotinylation to monitor NPC1L1-GFP endocytosis and show that ezetimibe does not alter the rate of NPC1L1-GFP endocytosis in cultured rat hepatocytes grown under normal growth conditions. As expected, NPC1L1-GFP endocytosis depends in part on C-terminal, cytoplasmically oriented sequences, but endocytosis does not require cholesterol binding to NPC1L1's N-terminal domain. In addition, two small- molecule inhibitors of general (and NPC1L1-GFP) endocytosis failed to inhibit the ezetimibe-sensitive uptake of [(3)H]cholesterol from taurocholate micelles. These experiments demonstrate that cholesterol uptake by NPC1L1 does not require endocytosis; moreover, ezetimibe interferes with NPC1L1's cholesterol adsorption activity without blocking NPC1L1 internalization in RH7777 cells. © 2016 Johnson and Pfeffer. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  8. Shunt Active and Series Active Filters-Based Power Quality Conditioner for Matrix Converter

    OpenAIRE

    P. Jeno Paul

    2011-01-01

    This paper proposes a series active filter and shunt active filter to minimize the power quality impact present in matrix converters instead of passive filter. A matrix converter produces significant harmonics and nonstandard frequency components into load. The proposed system compensates the sag and swell problems efficiently in matrix converter. The proposed system has been tested and validated on the matrix converter using MATLAB/Simulink software. Simulated results confirm that the active...

  9. Active power decoupling with reduced converter stress for single ...

    Indian Academy of Sciences (India)

    SUJATA BHOWMICK

    The analysis and the simulation results are shown to prove the effectiveness of the topology. Keywords. Single phase; double-frequency ripple; active power decoupling; reduced stress; reliability. 1. Introduction. The single-phase power electronic converters interfacing a. DC storage system or a DC source have the inherent.

  10. Shunt Active and Series Active Filters-Based Power Quality Conditioner for Matrix Converter

    Directory of Open Access Journals (Sweden)

    P. Jeno Paul

    2011-01-01

    Full Text Available This paper proposes a series active filter and shunt active filter to minimize the power quality impact present in matrix converters instead of passive filter. A matrix converter produces significant harmonics and nonstandard frequency components into load. The proposed system compensates the sag and swell problems efficiently in matrix converter. The proposed system has been tested and validated on the matrix converter using MATLAB/Simulink software. Simulated results confirm that the active power filters can maintain high performance for matrix converter.

  11. A Single Residue in Ebola Virus Receptor NPC1 Influences Cellular Host Range in Reptiles.

    Science.gov (United States)

    Ndungo, Esther; Herbert, Andrew S; Raaben, Matthijs; Obernosterer, Gregor; Biswas, Rohan; Miller, Emily Happy; Wirchnianski, Ariel S; Carette, Jan E; Brummelkamp, Thijn R; Whelan, Sean P; Dye, John M; Chandran, Kartik

    2016-01-01

    Filoviruses are the causative agents of an increasing number of disease outbreaks in human populations, including the current unprecedented Ebola virus disease (EVD) outbreak in western Africa. One obstacle to controlling these epidemics is our poor understanding of the host range of filoviruses and their natural reservoirs. Here, we investigated the role of the intracellular filovirus receptor, Niemann-Pick C1 (NPC1) as a molecular determinant of Ebola virus (EBOV) host range at the cellular level. Whereas human cells can be infected by EBOV, a cell line derived from a Russell's viper (Daboia russellii) (VH-2) is resistant to infection in an NPC1-dependent manner. We found that VH-2 cells are resistant to EBOV infection because the Russell's viper NPC1 ortholog bound poorly to the EBOV spike glycoprotein (GP). Analysis of panels of viper-human NPC1 chimeras and point mutants allowed us to identify a single amino acid residue in NPC1, at position 503, that bidirectionally influenced both its binding to EBOV GP and its viral receptor activity in cells. Significantly, this single residue change perturbed neither NPC1's endosomal localization nor its housekeeping role in cellular cholesterol trafficking. Together with other recent work, these findings identify sequences in NPC1 that are important for viral receptor activity by virtue of their direct interaction with EBOV GP and suggest that they may influence filovirus host range in nature. Broader surveys of NPC1 orthologs from vertebrates may delineate additional sequence polymorphisms in this gene that control susceptibility to filovirus infection. IMPORTANCE Identifying cellular factors that determine susceptibility to infection can help us understand how Ebola virus is transmitted. We asked if the EBOV receptor Niemann-Pick C1 (NPC1) could explain why reptiles are resistant to EBOV infection. We demonstrate that cells derived from the Russell's viper are not susceptible to infection because EBOV cannot bind to

  12. Singularities of projection of an active power in frequency converter

    Directory of Open Access Journals (Sweden)

    Є.К. Батуревич

    2005-03-01

    Full Text Available  The level of security of static single-phase watt-hour meters of an electric energy concerning a possibility of unauthorized takeoff of an electric energy by electric methods is analyses. The shortages of an active power in a pulse frequency converter are marked which are used in such watt-hour meters. The solutions on their refinement are offered.

  13. EBV reactivation as a target of luteolin to repress NPC tumorigenesis.

    Science.gov (United States)

    Wu, Chung-Chun; Fang, Chih-Yeu; Hsu, Hui-Yu; Chuang, Hsin-Ying; Cheng, Yu-Jhen; Chen, Yen-Ju; Chou, Sheng-Ping; Huang, Sheng-Yen; Lin, Su-Fang; Chang, Yao; Tsai, Ching-Hwa; Chen, Jen-Yang

    2016-04-05

    Nasopharyngeal carcinoma (NPC) is a malignancy derived from the epithelial cells of the nasopharynx. Although a combination of radiotherapy with chemotherapy is effective for therapy, relapse and metastasis after remission remain major causes of mortality. Epstein-Barr virus (EBV) is believed to be one of causes of NPC development. We demonstrated previously that EBV reactivation is important for the carcinogenesis of NPC. We sought, therefore, to determine whether EBV reactivation can be a target for retardation of relapse of NPC. After screening, we found luteolin is able to inhibit EBV reactivation. It inhibited EBV lytic protein expression and repressed the promoter activities of two major immediate-early genes, Zta and Rta. Furthermore, luteolin was shown to reduce genomic instability induced by recurrent EBV reactivation in NPC cells. EBV reactivation-induced NPC cell proliferation and migration, as well as matrigel invasiveness, were also repressed by luteolin treatment. Tumorigenicity in mice, induced by EBV reactivation, was decreased profoundly following luteolin administration. Together, these results suggest that inhibition of EBV reactivation is a novel approach to prevent the relapse of NPC.

  14. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    Multilevel inverters are getting more and more attracted because they have better output waveform quality and lower semiconductor voltage stress. The Z-source NPC is a kind of single stage multilevel inverter which has the ability of voltage boost. But the boost capability is relatively low when...... they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...... would have a higher output voltage gain. It is anticipated that it would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually requested. Experimental testing has already been conducted and verifies the theory....

  15. Olfactory deficits in Niemann-Pick type C1 (NPC1 disease.

    Directory of Open Access Journals (Sweden)

    Marina Hovakimyan

    Full Text Available BACKGROUND: Niemann-Pick type C disease (NPC is a rare autosomal recessive lipid storage disease characterized by progressive neurodegeneration. As only a few studies have been conducted on the impact of NPC on sensory systems, we used a mutant mouse model (NPC1(-/- to examine the effects of this disorder to morphologically distinct regions of the olfactory system, namely the olfactory epithelium (OE and olfactory bulb (OB. METHODOLOGY/PRINCIPAL FINDINGS: For structural and functional analysis immunohistochemistry, electron microscopy, western blotting, and electrophysiology have been applied. For histochemistry and western blotting, we used antibodies against a series of neuronal and glia marker proteins, as well as macrophage markers. NPC1(-/- animals present myelin-like lysosomal deposits in virtually all types of cells of the peripheral and central olfactory system. Especially supporting cells of the OE and central glia cells are affected, resulting in pronounced astrocytosis and microgliosis in the OB and other olfactory cortices. Up-regulation of Galectin-3, Cathepsin D and GFAP in the cortical layers of the OB underlines the critical role and location of the OB as a possible entrance gate for noxious substances. Unmyelinated olfactory afferents of the lamina propria seem less affected than ensheathing cells. Supporting the structural findings, electro-olfactometry of the olfactory mucosa suggests that NPC1(-/- animals exhibit olfactory and trigeminal deficits. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate a pronounced neurodegeneration and glia activation in the olfactory system of NPC1(-/-, which is accompanied by sensory deficits.

  16. N-terminal domain of the cholesterol transporter Niemann-Pick C1-like 1 (NPC1L1) is essential for α-tocopherol transport.

    Science.gov (United States)

    Kamishikiryo, Jun; Haraguchi, Misaki; Nakashima, Shunsuke; Tasaka, Yuka; Narahara, Hiroe; Sugihara, Narumi; Nakamura, Tetsuya; Morita, Tetsuo

    2017-04-29

    Both cholesterol and α-tocopherol are essential lipophilic nutrients for humans and animals. Although cholesterol in excess causes severe problems such as coronary heart disease, it is a necessary component of cell membranes and is the precursor for the biosynthesis of steroid hormones and bile acids. Niemann-Pick C1-like 1 (NPC1L1) is a cholesterol transporter that is highly expressed in the small intestine and liver in humans and plays an important role in cholesterol homeostasis. Cholesterol promotes NPC1L1 endocytosis, which is an early step in cholesterol uptake. Furthermore, α-tocopherol is the most active form of vitamin E, and sufficient amounts of vitamin E are critical for health. It has been reported that NPC1L1 mediates α-tocopherol absorption; however, the mechanisms underlying this process are unknown. In this study, we found that treatment of cells that stably express NPC1L1-GFP with α-tocopherol promotes NPC1L1 endocytosis, and the NPC1L1 inhibitor, ezetimibe, efficiently prevents the α-tocopherol-induced endocytosis of NPC1L1. Cholesterol binding to the N-terminal domain (NTD) of NPC1L1 (NPC1L1-NTD) is essential for NPC1L1-mediated cholesterol absorption. We found that α-tocopherol competitively binds NPC1L1-NTD with cholesterol. Furthermore, when cells stably expressed NPC1L1ΔNTD-GFP, α-tocopherol could not induce the endocytosis of NPC1L1ΔNTD. Taken together, these results demonstrate that NPC1L1 recognizes α-tocopherol via its NTD and mediates α-tocopherol uptake through the same mechanism as cholesterol absorption. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Standing wave tube electro active polymer wave energy converter

    Science.gov (United States)

    Jean, Philippe; Wattez, Ambroise; Ardoise, Guillaume; Melis, C.; Van Kessel, R.; Fourmon, A.; Barrabino, E.; Heemskerk, J.; Queau, J. P.

    2012-04-01

    Over the past 4 years SBM has developed a revolutionary Wave Energy Converter (WEC): the S3. Floating under the ocean surface, the S3 amplifies pressure waves similarly to a Ruben's tube. Only made of elastomers, the system is entirely flexible, environmentally friendly and silent. Thanks to a multimodal resonant behavior, the S3 is capable of efficiently harvesting wave energy from a wide range of wave periods, naturally smoothing the irregularities of ocean wave amplitudes and periods. In the S3 system, Electro Active Polymer (EAP) generators are distributed along an elastomeric tube over several wave lengths, they convert wave induced deformations directly into electricity. The output is high voltage multiphase Direct Current with low ripple. Unlike other conventional WECs, the S3 requires no maintenance of moving parts. The conception and operating principle will eventually lead to a reduction of both CAPEX and OPEX. By integrating EAP generators into a small scale S3, SBM achieved a world first: direct conversion of wave energy in electricity with a moored flexible submerged EAP WEC in a wave tank test. Through an extensive testing program on large scale EAP generators, SBM identified challenges in scaling up to a utility grid device. French Government supports the consortium consisting of SBM, IFREMER and ECN in their efforts to deploy a full scale prototype at the SEMREV test center in France at the horizon 2014-2015. SBM will be seeking strategic as well as financial partners to unleash the true potentials of the S3 Standing Wave Tube Electro Active Polymer WEC.

  18. Active power decoupling with reduced converter stress for single ...

    Indian Academy of Sciences (India)

    2) using smaller capacitance value, thus alleviating the use of electrolytic capacitor and in turn improving the lifetime of the converter. The circuit consists of a third leg, a storage capacitor and a storage inductor. The analysis and the simulation ...

  19. Comparative activity of three inhibitors of the angiotensin converting ...

    African Journals Online (AJOL)

    Three angiotensin converting enzyme (ACE) inhibitors, enalapril, lisinopril and captopril were tested in vivo by topical application on growth, development and whole body ecdysteroids in Ephestia kuehniella Zeller (Lepidoptera:Pyralidae), an important pest in stored products worldwide. The compounds were diluted in ...

  20. Imbalance between pulmonary angiotensin-converting enzyme and angiotensin-converting enzyme 2 activity in acute respiratory distress syndrome

    NARCIS (Netherlands)

    Wosten-van Asperen, Roelie M.; Bos, Albert; Bem, Reinout A.; Dierdorp, Barbara S.; Dekker, Tamara; van Goor, Harry; Kamilic, Jelena; van der Loos, Chris M.; van den Berg, Elske; Bruijn, Martijn; van Woensel, Job B.; Lutter, Rene

    2013-01-01

    Objective: Angiotensin-converting enzyme and its effector peptide angiotensin II have been implicated in the pathogenesis of acute respiratory distress syndrome. Recently, angiotensin-converting enzyme 2 was identified as the counter-regulatory enzyme of angiotensin-converting enzyme that converts

  1. Inactivating mutations in NPC1L1 and protection from coronary heart disease

    NARCIS (Netherlands)

    Stitziel, Nathan O.; Won, Hong-Hee; Morrison, Alanna C.; Peloso, Gina M.; Do, Ron; Lange, Leslie A.; Fontanillas, Pierre; Gupta, Namrata; Duga, Stefano; Goel, Anuj; Farrall, Martin; Saleheen, Danish; Ferrario, Paola; König, Inke; Asselta, Rosanna; Merlini, Piera A.; Marziliano, Nicola; Notarangelo, Maria Francesca; Schick, Ursula; Auer, Paul; Assimes, Themistocles L.; Reilly, Muredach; Wilensky, Robert; Rader, Daniel J.; Hovingh, G. Kees; Meitinger, Thomas; Kessler, Thorsten; Kastrati, Adnan; Laugwitz, Karl-Ludwig; Siscovick, David; Rotter, Jerome I.; Hazen, Stanley L.; Tracy, Russell; Cresci, Sharon; Spertus, John; Jackson, Rebecca; Schwartz, Stephen M.; Natarajan, Pradeep; Crosby, Jacy; Muzny, Donna; Ballantyne, Christie; Rich, Stephen S.; O'Donnell, Christopher J.; Abecasis, Goncalo; Sunyaev, Shamil; Nickerson, Deborah A.; Buring, Julie E.; Ridker, Paul M.; Chasman, Daniel I.; Austin, Erin; Ye, Zi; Kullo, Iftikhar J.; Weeke, Peter E.; Shaffer, Christian M.; Bastarache, Lisa A.; Denny, Joshua C.; Roden, Dan M.; Palmer, Colin; Deloukas, Panos; Lin, Dan-Yu; Tang, Zheng-zheng; Erdmann, Jeanette; Schunkert, Heribert; Danesh, John; Marrugat, Jaume; Elosua, Roberto; Ardissino, Diego; McPherson, Ruth; Watkins, Hugh; Reiner, Alex P.; Wilson, James G.; Altshuler, David; Gibbs, Richard A.; Lander, Eric S.; Boerwinkle, Eric; Gabriel, Stacey; Kathiresan, Sekar

    2014-01-01

    Ezetimibe lowers plasma levels of low-density lipoprotein (LDL) cholesterol by inhibiting the activity of the Niemann-Pick C1-like 1 (NPC1L1) protein. However, whether such inhibition reduces the risk of coronary heart disease is not known. Human mutations that inactivate a gene encoding a drug

  2. Five-Level Active-Neutral-Point-Clamped DC/DC Converter

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

    2016-01-01

    Multi-level converters are getting more and more attentions because of their obvious merits such as lower voltage stress and harmonic, smaller size of output filters, and so on. In this paper, a five-level active-neutral-point-clamped (5L-ANPC) dc/dc converter is proposed for power transfer...

  3. Device loading of modular multilevel converter MMC in wind power application

    DEFF Research Database (Denmark)

    Popova, L.; Pyrhönen, J.; Ma, Ke

    2014-01-01

    Modular multilevel converter (MMC) is a recently emerged multilevel topology for high-voltage high-power applications. However, in wind power application the performance of the MMC has not been deeply investigated. In this paper the application of MMC in wind energy systems is studied....... The converters used to connect the wind turbine to the grid having the rated active powers of 2MW and 10MW are designed and investigated. Electrical losses and thermal loading of the power devices in the proposed converter solutions are analyzed. The efficiency of the MMC converter under different P/Q boundaries...... defined by grid codes is investigated and compared with two-level and three-level NPC converters. It is concluded that it is possible to use the MMC in wind power application and the losses are distributed evenly between the sub-modules of the MMC converter. However, inside a sub-module the losses...

  4. Reduced VLDL clearance in Apoe(-/-)Npc1(-/-) mice is associated with increased Pcsk9 and Idol expression and decreased hepatic LDL-receptor levels.

    Science.gov (United States)

    Ishibashi, Minako; Masson, David; Westerterp, Marit; Wang, Nan; Sayers, Scott; Li, Rong; Welch, Carrie L; Tall, Alan R

    2010-09-01

    Niemann-Pick type C1 (NPC1) promotes the transport of LDL receptor (LDL-R)-derived cholesterol from late endosomes/lysosomes to other cellular compartments. NPC1-deficient cells showed impaired regulation of liver_X receptor (LXR) and sterol regulatory element-binding protein (SREBP) target genes. We observed that Apoe(-/-)Npc1(-/-) mice displayed a marked increase in total plasma cholesterol mainly due to increased VLDL, reflecting decreased clearance. Although nuclear SREBP-2 and Ldlr mRNA levels were increased in Apoe(-/-)Npc1(-/-) liver, LDL-R protein levels were decreased in association with marked induction of proprotein convertase subtilisin/kexin type 9 (Pcsk9) and inducible degrader of the LDL-R (Idol), both known to promote proteolytic degradation of LDL-R. While Pcsk9 is known to be an SREBP-2 target, marked upregulation of IDOL in Apoe(-/-)Npc1(-/-) liver was unexpected. However, several other LXR target genes also increased in Apoe(-/-)Npc1(-/-) liver, suggesting increased synthesis of endogenous LXR ligands secondary to activation of sterol biosynthesis. In conclusion, we demonstrate that NPC1 deficiency has a major impact on VLDL metabolism in Apoe(-/-) mice through modulation of hepatic LDL-R protein levels. In contrast to modest induction of hepatic IDOL with synthetic LXR ligands, a striking upregulation of IDOL in Apoe(-/-)Npc1(-/-) mice could indicate a role of endogenous LXR ligands in regulation of hepatic IDOL.

  5. Design and Control of Modular Multilevel Converter in an Active Front and Application

    CERN Document Server

    Asimakopoulos, Panagiotis; Prof Bongiorno, Massimo

    2013-09-01

    A proposed topology to operate as an Active Front End is the Modular Multilevel Converter. The Modular Multilevel Converter is a new solution in the field of medium and high power electronics. The converter's operation is based on the modular approach. It consists of modules, each one being a half-bridge connected in parallel to a capacitor. The special characteristic of this idea is that it is possible to build the sinusoidal waveform of the voltage by adding several modules in series in each phase-leg of the converter. An arm inductance is connected in series with the modules of every arm. In contrast to the two level voltage source converter, where the output phase voltage can be either plus or minus the half of the dc-link voltage, the MMC can change its output with steps equal to each module capacitor's voltage level.

  6. Neutral Point Clamped Npc Type Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    Purohit Sadanand Chandrashekhar

    2015-08-01

    Full Text Available Concept of the multilevel inverter is same as the other inverter which is to converts Direct current DC to Alternating current AC .The inverted current can be at any vital voltage and frequency with the use of pertinent transformers switching and control circuits. From the source like batteries solar panel wind turbine or fuel cell the inverter will convert the DC electricity to AC electricity. In this modern technology Power electronics is very important where it used in a great variety of product. With the high potential in high power for industry multilevel inverter will become most popular for so many applications.

  7. A new configuration for multilevel converters with diode clamped topology

    DEFF Research Database (Denmark)

    Nami, A.; Zare, F.; Ledwich, G.

    2008-01-01

    points in this type of converter is dc-voltage control. In this paper, a novel multi output dc-dc converter connected to a diode clamped topology is presented. This converter, for a given duty cycles, is able to regulate the capacitor voltage to provide an appropriate input voltage for NPC regardless...

  8. Nandrolone increases angiotensin-I converting enzyme activity in rats tendons

    OpenAIRE

    Marqueti, Rita de Cassia; Hashimoto, Nara Yumi; Durigan, João Luiz Quaglioti; Batista e Silva, Lívia Larissa; Almeida, Jeeser Alves de; Silva, Maria da Glória da; Oliveira, Edilamar Menezes de; Araújo, Heloisa Sobreiro Selistre de

    2015-01-01

    INTRODUCTION: The renin-angiotensin system (RAS) has been associated with several biological processes of the human body, regulating, among others blood pressure and water and electrolytes balance. Moreover, RAS also regulates connective tissue growth. Recently, studies have shown that the use of nandrolone modifies the angiotensin-I converting enzyme (ACE) activity and increases collagen deposition in the heart. OBJECTIVE: The aim of study was to evaluate the Angiotensin-I converting enzyme ...

  9. Diversity of glycosphingolipid GM2 and cholesterol accumulation in NPC1 patient-specific iPSC-derived neurons.

    Science.gov (United States)

    Trilck, Michaela; Peter, Franziska; Zheng, Chaonan; Frank, Marcus; Dobrenis, Kostantin; Mascher, Hermann; Rolfs, Arndt; Frech, Moritz J

    2017-02-15

    Niemann-Pick disease Type C1 (NPC1) is a rare progressive neurodegenerative disorder caused by mutations in the NPC1 gene. On the cellular level NPC1 mutations lead to an accumulation of cholesterol and gangliosides. As a thorough analysis of the severely affected neuronal cells is unfeasible in NPC1 patients, we recently described the cellular phenotype of neuronal cells derived from NPC1 patient iPSCs carrying the compound heterozygous mutation c.1836A>C/c.1628delC. Here we expanded the analysis to cell lines carrying the prevalent mutation c.3182T>C and the novel mutation c.1180T>C, as well as to the determination of GM2 and GM3 gangliosides in NPC1 patient-specific iPSC-derived neurons and glia cells. Immunocytochemical detection of GM2 revealed punctated staining pattern predominantly localized in neurons. Detection of cholesterol by filipin staining showed a comparable staining pattern, colocalized with GM2, indicating a deposit of GM2 and cholesterol in the same cellular compartments. Accumulations were not only restricted to cell bodies, but were also found in the neuronal extensions. A quantification of the GM2 amount by HPLC-MS/MS confirmed significantly higher amounts in neurons carrying a mutation. Additionally, these cells displayed a lowered activity of the catabolic enzyme Hex A, but not B4GALNT1. Molecular docking simulations indicated binding of cholesterol to Hex A, suggesting cholesterol influences the GM2 degradation pathway and, subsequently, leading to the accumulation of GM2. Taken together, this is the first study showing an accumulation of GM2 in neuronal derivatives of patient-specific iPSCs and thus proving further disease-specific hallmarks in this human in vitro model of NPC1. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Passivity Enhancement of Grid-Tied Converter by Series LC-Filtered Active Damper

    DEFF Research Database (Denmark)

    Bai, Haofeng; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    Series LC-filtered active damper can be used to stabilize the grid-tied voltage source converter in a non-ideal grid. The operation principle of the active damper is to mimic a damping resistance at the resonance frequencies. However, the selection of the damping resistance has not received much...... attention. Also, parasitic capacitance of the grid transmission line brings new challenge for the application of an active damper, which has not been discussed before. In order to fill these gaps, this paper first analyzes the stability of a grid-tied converter with the help of passivity. Based...

  11. High Voltage Power Converter for Large Wind Turbine

    DEFF Research Database (Denmark)

    Sztykiel, Michal

    system operates at 20 kV level - identical as for the collector distribution network. Medium voltage operation allows the converter unit along with the filter to be installed on the base platform inside the tower. In this manner, more space in the nacelle can be flexibly accommodated by the mechanical...... application. System B consists of the generator-side 2-level converter, DC/DC boost unit and a grid-side NPC-3L converter. System C is made of a seriesconnected full-bridge cells on the generator-side, and a grid-side NPC-5L converter. The performance of the proposed topologies is analyzed both under...

  12. Robust Vehicle Suspension System by Converting Active & Passive Control of a Vehicle to Semi-Active Control System Analytically

    National Research Council Canada - National Science Library

    Hassan Elahi; Dr. Riffat Asim Pasha; Dr. Asif Israr; Dr. M. Zubair Khan

    2014-01-01

    .... Passive Vehicle Suspension System is converted into Semi Active Vehicle System. Major advantage achieved by this system is that it adjusts the damping of the suspension system without the application of any actuator by using MATLAB® simulations...

  13. Angiotensin-converting enzyme activity and cognitive impairment during hypoglycaemia in healthy humans

    DEFF Research Database (Denmark)

    Pedersen-Bjergaard, Ulrik; Thomsen, Carsten E; Høgenhaven, Hans

    2008-01-01

    INTRODUCTION: In type 1 diabetes increased risk of severe hypoglycaemia is associated with high angiotensin-converting enzyme (ACE) activity. We tested in healthy humans the hypothesis that this association is explained by the reduced ability of subjects with high ACE activity to maintain normal ...

  14. Robust Design of LCL-Filters for Active Damping in Grid Converters

    DEFF Research Database (Denmark)

    Alzola, Rafael Pena; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    Grid converters require a simple inductor or an LCL-filter to limit the current ripples. The LCL-filter is nowadays the preferred solution as it allows lower inductance values. In order to solve the stability concerns, active damping is preferred to passive damping since it does not use dissipative...... elements. However, large variations in the grid inductance and resonances arising from parallel converters may still compromise the system stability. This calls for a robust design of LCL-filters with active damping. This paper proposes a design flow with little iteration for two well-known methods, namely...... lead-lag network and current capacitor feedback. The proposed formulas for the resonance frequency, grid and converter inductance ratio, and capacitance of the LCL-filter allow calculating all the LCL-filter parameters. An estimation for the achieved Total Harmonic Distortion (THD) of the grid current...

  15. Inhibition of Angiotensin-Converting Enzyme Activity by Flavonoids: Structure-Activity Relationship Studies

    Science.gov (United States)

    Guerrero, Ligia; Castillo, Julián; Quiñones, Mar; Garcia-Vallvé, Santiago; Arola, Lluis; Pujadas, Gerard; Muguerza, Begoña

    2012-01-01

    Previous studies have demonstrated that certain flavonoids can have an inhibitory effect on angiotensin-converting enzyme (ACE) activity, which plays a key role in the regulation of arterial blood pressure. In the present study, 17 flavonoids belonging to five structural subtypes were evaluated in vitro for their ability to inhibit ACE in order to establish the structural basis of their bioactivity. The ACE inhibitory (ACEI) activity of these 17 flavonoids was determined by fluorimetric method at two concentrations (500 µM and 100 µM). Their inhibitory potencies ranged from 17 to 95% at 500 µM and from 0 to 57% at 100 µM. In both cases, the highest ACEI activity was obtained for luteolin. Following the determination of ACEI activity, the flavonoids with higher ACEI activity (i.e., ACEI >60% at 500 µM) were selected for further IC50 determination. The IC50 values for luteolin, quercetin, rutin, kaempferol, rhoifolin and apigenin K were 23, 43, 64, 178, 183 and 196 µM, respectively. Our results suggest that flavonoids are an excellent source of functional antihypertensive products. Furthermore, our structure-activity relationship studies show that the combination of sub-structures on the flavonoid skeleton that increase ACEI activity is made up of the following elements: (a) the catechol group in the B-ring, (b) the double bond between C2 and C3 at the C-ring, and (c) the cetone group in C4 at the C-ring. Protein-ligand docking studies are used to understand the molecular basis for these results. PMID:23185345

  16. Miglustat Reverts the Impairment of Synaptic Plasticity in a Mouse Model of NPC Disease

    Directory of Open Access Journals (Sweden)

    G. D’Arcangelo

    2016-01-01

    Full Text Available Niemann-Pick type C disease is an autosomal recessive storage disorder, characterized by abnormal sequestration of unesterified cholesterol within the late endolysosomal compartment of cells and accumulation of gangliosides and other sphingolipids. Progressive neurological deterioration and insurgence of symptoms like ataxia, seizure, and cognitive decline until severe dementia are pathognomonic features of the disease. Here, we studied synaptic plasticity phenomena and evaluated ERKs activation in the hippocampus of BALB/c NPC1−/− mice, a well described animal model of the disease. Our results demonstrated an impairment of both induction and maintenance of long term synaptic potentiation in NPC1−/− mouse slices, associated with the lack of ERKs phosphorylation. We then investigated the effects of Miglustat, a recent approved drug for the treatment of NPCD. We found that in vivo Miglustat administration in NPC1−/− mice was able to rescue synaptic plasticity deficits, to restore ERKs activation and to counteract hyperexcitability. Overall, these data indicate that Miglustat may be effective for treating the neurological deficits associated with NPCD, such as seizures and dementia.

  17. Effects of Carbohydrates on the oNPG Converting Activity of ß-Galactosidases

    NARCIS (Netherlands)

    Warmerdam, A.; Wang, J.; Boom, R.M.; Janssen, A.E.M.

    2013-01-01

    The effects of high concentrations of carbohydrates on the o-nitrophenyl ß-D-galactopyranoside (oNPG) converting activity of ß-galactosidase from Bacillus circulans are studied to get a better understanding of the enzyme behavior in concentrated and complicated systems in which enzymatic synthesis

  18. Prediction of severe hypoglycaemia by angiotensin-converting enzyme activity and genotype in type 1 diabetes

    DEFF Research Database (Denmark)

    Pedersen-Bjergaard, U; Agerholm-Larsen, Birgit; Pramming, S

    2003-01-01

    AIMS/HYPOTHESIS: We have previously shown a strong relationship between high angiotensin-converting enzyme (ACE) activity, presence of the deletion (D) allele of the ACEgene and recall of severe hypoglycaemic events in patients with Type 1 diabetes. This study was carried out to assess this relat...

  19. Effects of Mooring Systems on the Performance of a Wave Activated Body Energy Converter

    DEFF Research Database (Denmark)

    Zanuttigh, Barbara; Angelelli, Elisa; Kofoed, Jens Peter

    2013-01-01

    Aim of this paper is to analyse the power and hydraulic performance of a floating Wave Energy Converter with the purpose at optimising its design for installation in arrays. The paper presents new experiments carried out in 1:30 scale on a single device of the Wave Activated Body type in the deep...

  20. A Color LED Driver Implemented by the Active Clamp Forward Converter

    Directory of Open Access Journals (Sweden)

    C.H. Chang

    2013-04-01

    Full Text Available Because light emitting diodes (LEDs have the advantages of dc working voltage, high luminescent efficiency, short ignition time, high reliability and pollution free, they have substituted for incandescent bulbs and fluorescent lamps gradually. In order to simplify circuit complexity, an active clamp forward converter with the sequential color display (SCD control is proposed to drive red, green and blue (RGB LED arrays. The proposed converter has zero-voltage switching (ZVS operations of both the main switch and the auxiliary switch, resulting in high system efficiency. Driving RGB LED arrays sequentially by one converter can save components and reduce cost significantly. Additionally, the pulse-width modulation (PWM control is applied to achieve a large chromaticity variation. The circuit operations are analyzed in detail and the circuit parameters are designed based on the practical considerations. Finally, an illustrative example is implemented to demonstrate the feasibility and validity of the proposed LED driver.

  1. A Voltage Doubler Circuit to Extend the Soft-switching Range of Dual Active Bridge Converters

    DEFF Research Database (Denmark)

    Qin, Zian; Shen, Yanfeng; Wang, Huai

    2017-01-01

    A voltage doubler circuit is realized to extend the soft-switching range of Dual Active Bridge (DAB) converters. No extra hardware is added to the DAB to form this circuit, since it is composed of the dc blocking capacitor and the low side full bridge converter, which already exist in DAB....... With the voltage doubler, the DAB converter can achieve soft switching and high efficiency when the low side dc voltage is close to 2 pu (1 pu is the high side dc voltage divided by the transformer turn ratio), which can be realized only when the low side dc voltage is close to 1 pu by using the conventional phase...... shift modulation in DAB. Thus the soft switching range is extended. The soft switching boundary conditions are derived. A map to show the soft switching or hard switching in the full load and voltage range is obtained. The feasibility and effectiveness of the proposed method is finally verified...

  2. A new model predictive control algorithm by reducing the computing time of cost function minimization for NPC inverter in three-phase power grids.

    Science.gov (United States)

    Taheri, Asghar; Zhalebaghi, Mohammad Hadi

    2017-11-01

    This paper presents a new control strategy based on finite-control-set model-predictive control (FCS-MPC) for Neutral-point-clamped (NPC) three-level converters. Containing some advantages like fast dynamic response, easy inclusion of constraints and simple control loop, makes the FCS-MPC method attractive to use as a switching strategy for converters. However, the large amount of required calculations is a problem in the widespread of this method. In this way, to resolve this problem this paper presents a modified method that effectively reduces the computation load compare with conventional FCS-MPC method and at the same time does not affect on control performance. The proposed method can be used for exchanging power between electrical grid and DC resources by providing active and reactive power compensations. Experiments on three-level converter for three Power Factor Correction (PFC), inductive and capacitive compensation modes verify the good and comparable performance. The results have been simulated using MATLAB/SIMULINK software. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  3. Cytokine and immunoglobulin production by PWM-stimulated peripheral and tumor-infiltrating lymphocytes of undifferentiated nasopharyngeal carcinoma (NPC patients

    Directory of Open Access Journals (Sweden)

    Bouzouita Kamel

    2004-09-01

    Full Text Available Abstract Background Undifferentiated Nasopharyngeal Carcinoma (NPC patients show a characteristic pattern of antibody responses to the Epstein-Barr virus (EBV which is regularly associated with this tumor. However, no EBV-specific cytotoxic activity is detectable by the standard chromium-release assay at both peripheral and intratumoral levels. The mechanisms underlying this discrepancy between the humoral and cellular immune responses in NPC are still unknown, but might be related to an imbalance in immunoregulatory interleukin production. In this report, we investigated the ability of peripheral (PBL and tumor- infiltrating (TIL lymphocytes of undifferentiated NPC patients to produce in vitro three interleukins (IL-2, IL-6, IL-10 and three immunoglobulin isotypes (IgM, IgG, IgA. Methods Lymphocytes from 17 patients and 17 controls were cultured in the presence of Pokeweed mitogen (PWM for 12 days and their culture supernatants were tested for interleukins and immunoglobulins by specific enzyme-linked immunosorbent assays (ELISA. Data were analysed using Student's t-test and probability values below 5% were considered significant. Results The data obtained indicated that TIL of NPC patients produced significantly more IL-2 (p = 0,0002, IL-10 (p = 0,020, IgM (p= 0,0003 and IgG (p Conclusion Taken together, our data reinforce the possibility of an imbalance in immunoregulatory interleukin production in NPC patients. An increased ability to produce cytokines such as IL-10 may underlie the discrepancy between humoral and cellular immune responses characteristic of NPC.

  4. Active-Pixel Image Sensor With Analog-To-Digital Converters

    Science.gov (United States)

    Fossum, Eric R.; Mendis, Sunetra K.; Pain, Bedabrata; Nixon, Robert H.

    1995-01-01

    Proposed single-chip integrated-circuit image sensor contains 128 x 128 array of active pixel sensors at 50-micrometer pitch. Output terminals of all pixels in each given column connected to analog-to-digital (A/D) converter located at bottom of column. Pixels scanned in semiparallel fashion, one row at time; during time allocated to scanning row, outputs of all active pixel sensors in row fed to respective A/D converters. Design of chip based on complementary metal oxide semiconductor (CMOS) technology, and individual circuit elements fabricated according to 2-micrometer CMOS design rules. Active pixel sensors designed to operate at video rate of 30 frames/second, even at low light levels. A/D scheme based on first-order Sigma-Delta modulation.

  5. An embryonic myosin converter domain influences Drosophila indirect flight muscle stretch activation, power generation and flight.

    Science.gov (United States)

    Wang, Qian; Newhard, Christopher S; Ramanath, Seemanti; Sheppard, Debra; Swank, Douglas M

    2014-01-15

    Stretch activation (SA) is critical to the flight ability of insects powered by asynchronous, indirect flight muscles (IFMs). An essential muscle protein component for SA and power generation is myosin. Which structural domains of myosin are significant for setting SA properties and power generation levels is poorly understood. We made use of the transgenic techniques and unique single muscle myosin heavy chain gene of Drosophila to test the influence of the myosin converter domain on IFM SA and power generation. Replacing the endogenous converter with an embryonic version decreased SA tension and the rate of SA tension generation. The alterations in SA properties and myosin kinetics from the converter exchange caused power generation to drop to 10% of control fiber power when the optimal conditions for control fibers - 1% muscle length (ML) amplitude and 150 Hz oscillation frequency - were applied to fibers expressing the embryonic converter (IFI-EC). Optimizing conditions for IFI-EC fiber power production, by doubling ML amplitude and decreasing oscillation frequency by 60%, improved power output to 60% of optimized control fiber power. IFI-EC flies altered their aerodynamic flight characteristics to better match optimal fiber power generation conditions as wing beat frequency decreased and wing stroke amplitude increased. This enabled flight in spite of the drastic changes to fiber mechanical performance.

  6. Passivity Enhancement of Grid-Tied Converters by Series LC-Filtered Active Damper

    DEFF Research Database (Denmark)

    Bai, Haofeng; Wang, Xiongfei; Loh, Poh Chiang

    2017-01-01

    The series LC-filtered active damper can be used for stabilizing a grid converter tied to the non-ideal grid. Its operation principle is to mimic a damping resistance at the resonance frequencies appearing in the grid. However, the selection of the damping resistance has not been fully analyzed...... in the literature. Its effect with parasitic capacitance present in the grid has also usually been ignored, even though it may bring new challenges to the active damper. To address these issues, passivity is applied to study the grid converter stability before the understanding gained is used for formulating...... a damping resistance selection method. The method formulated can further be improved by admittance shaping so that system stability can always be ensured even when considering grid parasitic capacitance and control imperfection. Experimental results obtained have verified the expectations, and hence...

  7. High Frequency AC Inductor Analysis and Design for Dual Active Bridge (DAB) Converters

    DEFF Research Database (Denmark)

    Zhang, Zhe; Andersen, Michael A. E.

    2016-01-01

    The dual active bridge (DAB) converter is an isolated bidirectional dc-dc topology which is the most critical part for the power conversion systems such as solid-state transformers (SST). This paper focuses on analysis and design of high frequency ac inductors which are the power interfacing...... the core loss and the winding loss are almost equal is selected as the optimal one. The experimental results are presented to verify the validity of the analysis and design....

  8. Early pharmacological inhibition of angiotensin-I converting enzyme activity induces obesity in adulthood

    OpenAIRE

    Kely ede Picoli Souza; Elton Dias da Silva; Elice Carneiro Batista; Felipe Castellani Gomes Reis; Sylvia Maria Affonso Silva; Charlles H M Castro; Jaqueline eLuz; Jorge Luiz Pesquero; Edson Lucas dos Santos; Joao Bosco Pesquero

    2015-01-01

    We have investigated early programming of body mass in order to understand the multifactorial etiology of obesity. Considering that the renin-angiotensin system (RAS) is expressed and functional in the white adipose tissue (WAT) and modulates its development, we reasoned whether early transitory inhibition of angiotensin-I converting enzyme activity after birth could modify late body mass development. Therefore, newborn Wistar rats were treated with enalapril (10 mg/kg of body mass) or saline...

  9. LCL-Filter Design for Robust Active Damping in Grid-Connected Converters

    DEFF Research Database (Denmark)

    Pena-Alzola, Rafael; Liserre, Marco; Blaabjerg, Frede

    2014-01-01

    in the grid inductance may compromise system stability, and this problem is more severe for parallel converters. This situation, typical of rural areas with solar and wind resources, calls for robust LCL-filter design. This paper proposes a design procedure with remarkable results under severe grid inductance......Grid-connected converters employ LCL-filters, instead of simple inductors, because they allow lower inductances while reducing cost and size. Active damping, without dissipative elements, is preferred to passive damping for solving the associated stability problems. However, large variations...... inductance, and the filter capacitance and total inductance. An estimation for the grid current total harmonic distortion (THD) is also proposed. Simulation and experiments validate the proposals....

  10. Interleukin-1 beta converting enzyme requires oligomerization for activity of processed forms in vivo.

    Science.gov (United States)

    Gu, Y; Wu, J; Faucheu, C; Lalanne, J L; Diu, A; Livingston, D J; Su, M S

    1995-05-01

    Interleukin-1 beta converting enzyme (ICE) is composed of 10' (p10) and 20 kDa (p20) subunits, which are derived from a common 45 kDa precursor. Recent crystallographic studies have shown that ICE exists as a tetramer (p20/p10)2 in the crystal lattice. We provide evidence that the p10 and p20 subunits of ICE associate as oligomers in transfected COS cells. Using intragenic complementation, we show that the activity of a p10/p10 interface mutant defective in autoprocessing can be restored by co-expression with active site ICE mutants. Different active site mutants can also complement each other by oligomerization to form active ICE. These studies indicate that ICE precursor polypeptides may associate in different quaternary structures and that oligomerization is required for autoprocessing. Furthermore, integenic complementation of active site mutants of ICE and an ICE homolog restores autoprocessing activity, suggesting that hetero-oligomerization occurs between ICE homologs.

  11. Robust Vehicle Suspension System by Converting Active & Passive Control of a Vehicle to Semi-Active Control System Analytically

    Directory of Open Access Journals (Sweden)

    Hassan Elahi

    2014-12-01

    Full Text Available In this research work a simplified translational model of an automotive suspension system is constructed by only considering the translation motion of one wheel of a car. Passive Vehicle Suspension System is converted into Semi Active Vehicle System. Major advantage achieved by this system is that it adjusts the damping of the suspension system without the application of any actuator by using MATLAB® simulations. The semi-active control is found to control the vibration of suspension system very well.

  12. A novel active T-type three-level converter with open-circuit fault-tolerant control

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede

    2015-01-01

    This paper proposes a novel active T-type three-level converter concept with fault-tolerant control. With the proposed topology, the converter can be operated continuously under open-circuit faults. It is shown that the proposed topology not only can keep its outputs under open-circuit fault cond...

  13. Effect of Mechanical Activation Treatment on the Recovery of Vanadium from Converter Slag

    Science.gov (United States)

    Xiang, Junyi; Huang, Qingyun; Lv, Xuewei; Bai, Chenguang

    2017-10-01

    The high roasting temperature and low leaching efficiency of vanadium from vanadium-bearing converter slag are regarded as the main factors significantly influencing the application of calcification roasting-acid leaching processes in the cleaner production of vanadium. In this study, a mechanical activation treatment was performed to enhance the extraction of vanadium from converter slag. The enhancement effects obtained from mechanical activation were comprehensively evaluated through indices such as the roasting temperature and leaching efficiency. The effects of mechanical activation time, roasting temperature, leaching temperature, solid to liquid ratio, particle size, and acid concentration on the leaching efficiency were investigated. Microstructure morphology and elemental analyses of the raw materials and leaching residue were also investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results demonstrated that the mechanical activation significantly decreased the optimum roasting temperature from 1173 K to 1073 K (900 °C to 800 °C) and increased the leaching efficiency from 86.0 to 90.9 pct.

  14. Enhanced photosynthetic activity in Spinacia oleracea by spectral modification with a photoluminescent light converting material.

    Science.gov (United States)

    Xia, Qi; Batentschuk, Miroslaw; Osvet, Andres; Richter, Peter; Häder, Donat P; Schneider, Juergen; Brabec, Christoph J; Wondraczek, Lothar; Winnacker, Albrecht

    2013-11-04

    The spectral conversion of incident sunlight by appropriate photoluminescent materials has been a widely studied issue for improving the efficiency of photovoltaic solar energy harvesting. By using phosphors with suitable excitation/emission properties, also the light conditions for plants can be adjusted to match the absorption spectra of chlorophyll dyes, in this way increasing the photosynthetic activity of the plant. Here, we report on the application of this principle to a high plant, Spinacia oleracea. We employ a calcium strontium sulfide phosphor doped with divalent europium (Ca0.4Sr0.6S:Eu(2+), CSSE) on a backlight conversion foil in photosynthesis experiments. We show that this phosphor can be used to effectively convert green to red light, centering at a wavelength of ~650 nm which overlaps the absorption peaks of chlorophyll a/b pigments. A measurement system was developed to monitor the photosynthetic activity, expressed as the CO2 assimilation rate of spinach leaves under various controlled light conditions. Results show that under identical external light supply which is rich in green photons, the CO2 assimilation rate can be enhanced by more than 25% when the actinic light is modified by the CSSE conversion foil as compared to a purely reflecting reference foil. These results show that the phosphor could be potentially applied to modify the solar spectrum by converting the green photons into photosynthetically active red photons for improved photosynthetic activity.

  15. Enhanced static ground power unit based on flying capacitor based h-bridge hybrid active-neutral-point-clamped converter

    DEFF Research Database (Denmark)

    Abarzadeh, Mostafa; Madadi Kojabadi, Hossein; Deng, Fujin

    2016-01-01

    Static power converters have various applications, such as static ground power units (GPUs) for airplanes. This study proposes a new configuration of a static GPU based on a novel nine-level flying capacitor h-bridge active-neutral-point-clamped (FCHB_ANPC) converter. The main advantages of the p......Static power converters have various applications, such as static ground power units (GPUs) for airplanes. This study proposes a new configuration of a static GPU based on a novel nine-level flying capacitor h-bridge active-neutral-point-clamped (FCHB_ANPC) converter. The main advantages...... demonstrate the validity and feasibility of the proposed converter and the modulation method under various operating conditions....

  16. Angiotensin-converting enzyme activity is reduced in brain microvessels of spontaneously hypertensive rats.

    Science.gov (United States)

    Kobayashi, H; Take, K; Wada, A; Izumi, F; Magnoni, M S

    1984-06-01

    Angiotensin -converting enzyme (ACE) activity in brain microvessels of spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) controls was measured. Cerebral microvessels, prepared from the cerebral cortices by the albumin flotation and glass bead filtration technique, were free of neuronal and glial elements. ACE activity in brain microvessels of SHR was lower than that of WKY. A Woolf - Augustinsson -Hofstee plot showed that the reduction of the enzyme activity in SHR was due to a 30% decrease in Vmax, without any change in Km for substrate. The decrease of ACE activity in brain microvessels of SHR may indicate an impairment of the central renin-angiotensin system and may be related to cerebral microvascular dysfunctions occurring in hypertension.

  17. Polyunsaturated fatty acids down-regulate in vitro expression of the key intestinal cholesterol absorption protein NPC1L1: no effect of monounsaturated nor saturated fatty acids.

    Science.gov (United States)

    Alvaro, Adriana; Rosales, Roser; Masana, Lluís; Vallvé, Joan-Carles

    2010-06-01

    Several transporter proteins regulate intestinal cholesterol absorption. Of these proteins, NPC1L1 is a major contributor to this process. Fatty acids (FAs) modulate cholesterol absorption by a mechanism that remains unknown. We evaluate the effect of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) on the expression of NPC1L1 and others proteins associated with cholesterol absorption (SR-BI, ABCG5, ABCG8, ABCA1, CAV-1, ANX-2) in human enterocytes in vitro. The role of SREBPs, PPARs, LXR and RXR in this process was also investigated. Caco-2/TC-7 enterocytes were incubated for 24 h with a wide range of concentrations of FA-bovine serum albumin (50-300 microM). Gene expression was analyzed by quantitative real-time PCR. The NPC1L1 protein present in enterocyte membranes was analyzed using Western blot. NPC1L1 mRNA levels were reduced 35-58% by the n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (PLinoleic acid (n-6), palmitic acid and oleic acid did not affect NPC1L1 mRNA expression. ABCA1 mRNA levels were reduced 44-70% by n-6 arachidonic acid and 43-55% by n-3 EPA (P<.05). LXR and LXR+RXR agonists decreased NPC1L1 mRNA expression by 28% and 57%, respectively (P<.05). A concentration of 200 microM of EPA and DHA decreased NPC1L1 protein expression in enterocyte membranes by 58% and 59%, respectively. We have demonstrated that the PUFAs n-3 EPA and DHA down-regulate NPC1L1 mRNA expression. In addition, PUFAs also down-regulate NPC1L1 protein expression in enterocyte membranes. LXR and RXR activation induced a similar repression effect. The lipid-lowering effect of n-3 PUFAs could be mediated in part by their action at the NPC1L1 gene level. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  18. Modelling and analysis of the transformer current resonance in dual active bridge converters

    DEFF Research Database (Denmark)

    Qin, Zian; Shen, Zhan; Blaabjerg, Frede

    2017-01-01

    Due to the parasitic capacitances of the transformer and inductor in Dual Active Bridge (DAB) converters, resonance happens in the transformer currents. This high frequency resonant current flowing into the full bridges will worsen their soft-switching performance and thereby reduce its efficiency....... In order to study the generation mechanism of this current resonance, the impedance of the transformer and inductor with parasitic components is modelled in this digest. Then, based on the impedance model, an approach is proposed to mitigate the current resonance. Finally, both the impedance model...... and the current resonance mitigation approach are verified by simulated results....

  19. Linear Active Disturbance Rejection Control for LCL Type Grid-connected Converter

    DEFF Research Database (Denmark)

    Lu, Jinghang; Savaghebi, Mehdi; Guerrero, Josep M.

    2016-01-01

    This paper presents a linear active disturbance rejection control (LADRC) for grid-connected converter with LCL filter. The high rejection performance for external disturbance, internal decoupling, parameter variation is achieved by adopting extended state observer(ESO) and designing controller...... with direct pole placement. Robustness of parameter uncertainty and sensitivity of input disturbance are analyzed in frequency domain to demonstrate the superior characteristic in disturbance rejection. The theoretical analysis is verified in Matlab/Simulink. The simulation results show the excellent...... capability of rejection in grid voltage disturbance....

  20. Modelling and analysis of the transformer current resonance in dual active bridge converters

    DEFF Research Database (Denmark)

    Qin, Zian; Shen, Zhan; Blaabjerg, Frede

    2017-01-01

    Due to the parasitic capacitances of the transformer and inductor in Dual Active Bridge (DAB) converters, resonance happens in the transformer currents. This high frequency resonant current flowing into the full bridges will worsen their soft-switching performance and thereby reduce its efficiency....... In order to study the generation mechanism of this current resonance, the impedance of the transformer and inductor with parasitic components is modelled in this digest. Then, based on the impedance model, an approach is proposed to mitigate the current resonance. Finally, both the impedance model...

  1. Hysteresis Current Control Based Shunt Active Power Filter for Six Pulse Ac/Dc Converter

    OpenAIRE

    Rakesh Kumar Pandey; Vaibhav Purwar; Nikhlesh Sharma

    2017-01-01

    In this paper the simulation of Shunt Active power Filter using P-Q theory and PI controller has been presented. This SAPF compensates the harmonic currents drawn by three phase six pulse AC/DC converter. The process of compensation is done by calculating the instantaneous reactive power losses using p-q theory and the PI controller to reduce the ripple voltage of the dc capacitor of the PWM-VSI. This approach is different from conventional approach and provides very effective sol...

  2. Enhanced Stability of Capacitor-Current Feedback Active Damping for LCL-Filtered Grid Converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The proportional capacitor-current feedback active damping method has been widely used to suppress the LCL-filter resonance. However, the time delay in the damping control loop may lead to non-minimum phase or even unstable responses when the resonance frequency varies in a wide range. To improve...... method against grid inductance variation is proved by z-domain and s-domain analyses. Finally, experimental results validate the effectiveness of the proposed method on a three-phase grid-connected converter....

  3. Nandrolone increases angiotensin-I converting enzyme activity in rats tendons

    Directory of Open Access Journals (Sweden)

    Rita de Cassia Marqueti

    2015-06-01

    Full Text Available INTRODUCTION: The renin-angiotensin system (RAS has been associated with several biological processes of the human body, regulating, among others blood pressure and water and electrolytes balance. Moreover, RAS also regulates connective tissue growth. Recently, studies have shown that the use of nandrolone modifies the angiotensin-I converting enzyme (ACE activity and increases collagen deposition in the heart. OBJECTIVE: The aim of study was to evaluate the Angiotensin-I converting enzyme (ACE activity in the superficial flexor tendon (SFT and in serum after load exercise in combination with anabolic androgenic steroid (AAS administration after training session and six weeks of detraining. METHODS: Forty-eight Wistar rats were used into two groups (G1 and G2 subdivided into four subgroups: Sedentary (S; trained (T; AAS-treated (Deca-Durabolin(r, 5mg/kg, twice a week sedentary rats (AAS and AAS-treated and trained animals (AAST. Trained groups performed jumps in water: four series of 10 jumps each, followed by a 30 sec interval between the series, for seven weeks. RESULTS: Training increased ACE activity in the SFT compared to the control group (p <0.05. Both AAS and AAST groups presented higher ACE activity levels (p < 0.05. The AAST increased the ACE activity only compared to the trained animals. Only the AAST group presented significant higher levels of ACE in the serum. In the G2 group, all experimental groups presented decreased ACE activity in the serum and in the tendon, as compared to the control group. CONCLUSION: This study indicates that AAS administration and its combination with exercise increased ACE activity of tendons. AAS abuse could compromise tendon adaptation causing maladaptive remodeling.

  4. Activity of angiotensin-converting enzyme and risk of severe hypoglycaemia in type 1 diabetes mellitus

    DEFF Research Database (Denmark)

    Pedersen-Bjergaard, U; Agerholm-Larsen, Birgit; Pramming, S

    2001-01-01

    BACKGROUND: The insertion (I) allele of the angiotensin-converting-enzyme (ACE) gene occurs at increased frequency in endurance athletes. This association suggests that low ACE activity is favourable for performance in conditions with limited substrate availability. Such conditions occur in endur......BACKGROUND: The insertion (I) allele of the angiotensin-converting-enzyme (ACE) gene occurs at increased frequency in endurance athletes. This association suggests that low ACE activity is favourable for performance in conditions with limited substrate availability. Such conditions occur...... in type 1 diabetes. METHODS: Consecutive adult outpatients with type 1 diabetes, untreated with ACE inhibitors or angiotensin-II-receptor antagonists (n=207) reported their experience of mild and severe hypoglycaemia during the previous 1 year and 2 years. The patients were further characterised...... by diabetes history, degree of hypoglycaemia awareness, measurement of C-peptide, haemoglobin A(1c), and serum ACE concentrations, and determination of ACE genotype. FINDINGS: Patients with the DD genotype had a relative risk of severe hypoglycaemia in the preceding 2 years of 3.2 (95% CI 1.4-7.4) compared...

  5. A High Step-Down Interleaved Buck Converter with Active-Clamp Circuits for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2012-12-01

    Full Text Available In this paper, a high step-down interleaved buck coupled-inductor converter (IBCC with active-clamp circuits for wind energy conversion has been studied. In high step-down voltage applications, an IBCC can extend duty ratio and reduce voltage stresses on active switches. In order to reduce switching losses of active switches to improve conversion efficiency, a IBCC with soft-switching techniques is usually required. Compared with passive-clamp circuits, the IBCC with active-clamp circuits have lower switching losses and minimum ringing voltage of the active switches. Thus, the proposed IBCC with active-clamp circuits for wind energy conversion can significantly increase conversion efficiency. Finally, a 240 W prototype of the proposed IBCC with active-clamp circuits was built and implemented. Experimental results have shown that efficiency can reach as high as 91%. The proposed IBCC with active-clamp circuits is presented in high step-down voltage applications to verify the performance and the feasibility for energy conversion of wind turbines.

  6. A Five Level NPC Inverter Controlled by Using SHEPWM Strategy

    Directory of Open Access Journals (Sweden)

    Noureddine Ould Cherchali

    2011-01-01

    Full Text Available The object of this paper is to analyse the behavior and the performances of a three-phase induction machine supplied with a five level neutral-point-clamped (NPC inverter controlled by Selective Harmonic Eliminated Pulse-Width Modulation Technique (SHEPWM. First, the modeling of the inverter and the machine is presented. Thereafter, a theoretical study of the harmonics elimination strategy is detailed; where the genetic algorithm (GA for elimination purposes is used. After that, this strategy is validated by simulation. Finally, a behavior of the induction machine controlled with this inverter is presented.

  7. Effect of Jatropha curcas Peptide Fractions on the Angiotensin I-Converting Enzyme Inhibitory Activity

    Science.gov (United States)

    Segura-Campos, Maira R.; Peralta-González, Fanny; Castellanos-Ruelas, Arturo; Chel-Guerrero, Luis A.; Betancur-Ancona, David A.

    2013-01-01

    Hypertension is one of the most common worldwide diseases in humans. Angiotensin I-converting enzyme (ACE) plays an important role in regulating blood pressure and hypertension. An evaluation was done on the effect of Alcalase hydrolysis of defatted Jatropha curcas kernel meal on ACE inhibitory activity in the resulting hydrolysate and its purified fractions. Alcalase exhibited broad specificity and produced a protein hydrolysate with a 21.35% degree of hydrolysis and 34.87% ACE inhibition. Ultrafiltration of the hydrolysate produced peptide fractions with increased biological activity (24.46–61.41%). Hydrophobic residues contributed substantially to the peptides' inhibitory potency. The 5–10 and Jatropha kernel have potential applications in alternative hypertension therapies, adding a new application for the Jatropha plant protein fraction and improving the financial viability and sustainability of a Jatropha-based biodiesel industry. PMID:24224169

  8. Utility of angiotensin-converting enzyme activity in aqueous humor in the diagnosis of ocular sarcoidosis.

    Science.gov (United States)

    Mihailovic-Vucinic, Violeta; Popevic, Ljubica; Popevic, Spasoje; Stjepanovic, Mihailo; Aleksic, Andjelka; Stanojevic-Paovic, Anka

    2017-10-01

    Many studies include elevated activity of angiotensin-converting enzyme (ACE) in serum in sarcoidosis and in ocular sarcoidosis as well, but there are only a few analyzing ACE activities in aqueous humor. The aim of this study is to illuminate the diagnostic value of ACE in aqueous humor in patients with ocular sarcoidosis. We analyzed twenty patients with ocular sarcoidosis and 18 patients with nonocular involvement. All patients have biopsy-positive sarcoidosis of the lungs and/or mediastinal lymph nodes. Blood samples for ACE serum levels were obtained from all patients. Aqueous humor samples were taken by paracentesis with a 25-gauge needle in local anesthesia. With appropriate statistical tests, we compared ACE activity in serum and aqueous humor in patients with and without ocular sarcoidosis. The majority of our patients with ocular sarcoidosis were female (12/20), also in the group with systemic sarcoidosis and without ocular involvement (12/6). Mean age of the whole analyzed group of sarcoidosis patients was 45 ± 6 years. There is no statistically significant difference in ACE activity in serum between two groups of patients (with and without ocular sarcoidosis). There is statistically significant difference in ACE activity in aqueous humor among patients with ocular and nonocular sarcoidosis. ACE activity in aqueous humor is significantly higher in patients with ocular sarcoidosis. Increased ACE activity in aqueous humor can point to a diagnosis of ocular sarcoidosis, without the need for ocular biopsy.

  9. Inhibition of angiotensin converting enzyme activity by flavanol-rich foods.

    Science.gov (United States)

    Actis-Goretta, Lucas; Ottaviani, Javier I; Fraga, Cesar G

    2006-01-11

    Angiotensin converting enzyme (ACE) activity was evaluated in the presence of flavanol-rich foods, i.e., wines, chocolates, and teas, and of purified flavonoids. All foods assayed inhibited ACE activity, red wines being more effective than white wine, and green tea more effective than black tea. The inhibition of ACE activity was associated with both phenolic and flavanol content in the foods. When isolated polyphenols were assayed, procyanidins (dimer and hexamer) and epigallocatechin significantly inhibited enzyme activity; similar concentrations of (+)-catechin, (-)-epicatechin, gallic acid, chlorogenic acid, caffeic acid, quercetin, kaempferol, and resveratrol were ineffective. When ACE activity was assayed in rat kidney membranes in the presence of chocolate extracts or purified procyanidins, it was observed that the inhibition depended on the chocolate content of flavanols and the number of flavanol units constituting the procyanidin. These experiments demonstrate that flavanols either isolated or present in foods could inhibit ACE activity. The occurrence of such inhibition in vivo needs to be determined, although is supported by the association between the consumption of flavanol-rich foods and reductions in blood pressure observed in several experimental models.

  10. An active current-sensing constant-frequency HCC buck converter using phase-frequency-locked techniques.

    Science.gov (United States)

    Chen, Jiann-Jong

    2008-04-01

    A hysteresis-current-controlled (HCC) buck converter with active current-sensing and phase-frequencylocked techniques is presented in this paper. The proposed active current-sensing technique can not only consume less power than previous techniques, but also fully sense the inductor current. Although the buck converter is HCC, the switching frequency can be constant due to the devised phase-frequency-locked technique. The proposed converter has been designed and implemented with TSMC 0.35 microm DPQM CMOS processes. It is shown in the experimental results that the HCC buck converter features the following characteristics: 1) up to 800 mA of load current, 2) wide input and output voltage range, 3) high power efficiency, and 4) constant-frequency operation.

  11. NREL Pyrheliometer Comparisons: September 26-October 7, 2016 (NPC-2016)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, Ibrahim [National Renewable Energy Lab. (NREL), Golden, CO (United States); Dooraghi, Mike [National Renewable Energy Lab. (NREL), Golden, CO (United States); Andreas, Afshin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Habte, Aron [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-10-01

    Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for developing and deploying solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations that are traceable to an international standard is the first step in producing research-quality solar irradiance measurements. National Renewable Energy Laboratory (NREL) pyrheliometer comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owners and operators, each NPC provides an opportunity to determine the unique World Radiometric Reference transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the WRR. NPC-2016 was September 26 through October 7, 2016. Participants operated 45 absolute cavity radiometers and 27 conventional thermopile-based pyrheliometers to simultaneously measure clear-sky, direct normal solar irradiance during this period.

  12. Psychiatric and neurological symptoms in patients with Niemann-Pick disease type C (NP-C): Findings from the International NPC Registry.

    Science.gov (United States)

    Bonnot, Olivier; Gama, Clarissa S; Mengel, Eugen; Pineda, Mercè; Vanier, Marie T; Watson, Louise; Watissée, Marie; Schwierin, Barbara; Patterson, Marc C

    2017-10-09

    Niemann-Pick disease type C (NP-C) is a rare inherited neurovisceral disease that should be recognised by psychiatrists as a possible underlying cause of psychiatric abnormalities. This study describes NP-C patients who had psychiatric manifestations at enrolment in the international NPC Registry, a unique multicentre, prospective, observational disease registry. Treating physicians' data entries describing psychiatric manifestations in NPC patients were coded and grouped by expert psychiatrists. Out of 386 NP-C patients included in the registry as of October 2015, psychiatric abnormalities were reported to be present in 34% (94/280) of those with available data. Forty-four patients were confirmed to have identifiable psychiatric manifestations, with text describing these psychiatric manifestations. In these 44 patients, the median (range) age at onset of psychiatric manifestations was 17.9 years (2.5-67.9; n = 15), while the median (range) age at NP-C diagnosis was 23.7 years (0.2-69.8; n = 34). Almost all patients (43/44; 98%) had an occurrence of ≥1 neurological manifestation at enrolment. These data show that substantial delays in diagnosis of NP-C are long among patients with psychiatric symptoms and, moreover, patients presenting with psychiatric features and at least one of cognitive impairment, neurological manifestations, and/or visceral symptoms should be screened for NP-C.

  13. Changes in vasopressin-converting aminopeptidase activity in the rat pineal gland during summer : Relationship to vasopressin contents

    NARCIS (Netherlands)

    Liu, B.; Burbach, J.P.H.

    Vasopressin (VP)-converting aminopeptidase (VP-AP) activity and VP contents were measured in single rat pineal glands during the summer of two successive years. The peptidase activity decreased significantly in August. The lowest activity (±SEM) of 0.18±0.02 pmol·hour−1 was recorded on August 14,

  14. Changes in vasopressin-converting aminopeptidase activity in the rat pineal gland during summer : Relationship to vasopressin contents

    NARCIS (Netherlands)

    Liu, B.; Burbach, J.P.H.

    1988-01-01

    Vasopressin (VP)-converting aminopeptidase (VP-AP) activity and VP contents were measured in single rat pineal glands during the summer of two successive years. The peptidase activity decreased significantly in August. The lowest activity (±SEM) of 0.18±0.02 pmol·hour−1 was recorded on August 14,

  15. Power Capability Investigation Based on Electrothermal Models of Press-pack IGBT Three-Level NPC and ANPC VSCs for Multimegawatt Wind Turbines

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2012-01-01

    capability investigations regarding a sample grid code's reactive power requirement show that 3L-ANPC-VSC results in 32% better power capability than 3L-NPC-VSC at the switching frequency of 1050 Hz. Furthermore, 3L-ANPC-VSC with 57% higher switching frequency (1650 Hz) and 33% smaller switching ripple...... to provide reactive power support as an ancillary service. For multimegawatt full-scale wind turbines, power capability depends on converter topology and semiconductor switch technology. As power capability limiting factors, switch current, semiconductor junction temperature, and converter output voltage...

  16. Mixed micellar liquid chromatography methods: modelling quantitative retention-activity relationships of angiotensin converting enzyme inhibitors.

    Science.gov (United States)

    Wu, Li-Ping; Cui, Yan; Xiong, Mei-Jin; Wang, Shu-Rong; Chen, Cong; Ye, Li-Ming

    2008-11-01

    The capability of biopartitioning micellar chromatography (BMC), using pure Brij35 solution and mixed micellar system of Brij35-SDS (85:15) as mobile phase, to describe and estimate bioactivities of angiotensin converting enzyme inhibitors at different pH has been studied. Quantitative retention-activity relationships (QRAR) in BMC were investigated for these compounds. The obtained BMC(Brij35-SDS)-QRAR models were compared with the traditional BMC(Brij35)-QRAR, and better statistically models were obtained using Brij35-SDS retention data. The superiority of BMC(Brij35-SDS)-QRAR is due to the fact that the mixed micellar mobile phase can simulate the resting membrane potential and the conformation of the long hydrophilic polyoxyethylene chains remains unchanged.

  17. A Single Residue in Ebola Virus Receptor NPC1 Influences Cellular Host Range in Reptiles

    Science.gov (United States)

    2016-09-07

    they serve as receptors (severe 74   acute respiratory syndrome -related coronaviruses (11, 12); New World mammarenaviruses, ca-75   nine parvoviruses...previ-308   ously described (22), to stably overexpress the NPC1 constructs in CHO-M12 cells, which con-309   tain a deletion in the NPC1 locus (26...FreeStyle™ 311   293 expression medium (Thermo Fisher Scientific) at 37˚C and 8% CO2. 312   313   NPC1 constructs 314   NPC1 domain C sequences

  18. Hepatic NPC1L1 overexpression ameliorates glucose metabolism in diabetic mice via suppression of gluconeogenesis.

    Science.gov (United States)

    Kurano, Makoto; Hara, Masumi; Satoh, Hiroaki; Tsukamoto, Kazuhisa

    2015-05-01

    Inhibition of intestinal NPC1L1 by ezetimibe has been demonstrated to improve glucose metabolism in rodent models; however, the role of hepatic NPC1L1 in glucose metabolism has not been elucidated. In this study, we analyzed the effects of hepatic NPC1L1 on glucose metabolism. We overexpressed NPC1L1 in the livers of lean wild type mice, diet-induced obesity mice and db/db mice with adenoviral gene transfer. We found that in all three mouse models, hepatic NPC1L1 overexpression lowered fasting blood glucose levels as well as blood glucose levels on ad libitum; in db/db mice, hepatic NPC1L1 overexpression improved blood glucose levels to almost the same as those found in lean wild type mice. A pyruvate tolerance test revealed that gluconeogenesis was suppressed by hepatic NPC1L1 overexpression. Further analyses revealed that hepatic NPC1L1 overexpression decreased the expression of FoxO1, resulting in the reduced expression of G6Pase and PEPCK, key enzymes in gluconeogenesis. These results indicate that hepatic NPC1L1 might have distinct properties of suppressing gluconeogenesis via inhibition of FoxO1 pathways. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Early pharmacological inhibition of angiotensin-I converting enzyme activity induces obesity in adulthood

    Directory of Open Access Journals (Sweden)

    Kely ede Picoli Souza

    2015-04-01

    Full Text Available We have investigated early programming of body mass in order to understand the multifactorial etiology of obesity. Considering that the renin-angiotensin system is expressed and functional in the white adipose tissue (WAT and modulates its development, we reasoned whether early transitory inhibition of angiotensin-I converting enzyme activity after birth could modify late body mass development. Therefore, newborn Wistar rats were treated with enalapril (10 mg/kg of body mass or saline, starting at the first day of life until the age of 16 days. Between days 90th and 180th, a group of these animals received high fat diet (HFD. Molecular, biochemical, histological and physiological data were collected. Enalapril treated animals presented hyperphagia, overweight and increased serum level of triglycerides, total cholesterol and leptin, in adult life. Body composition analyses revealed higher fat mass with increased adipocyte size in these animals. Molecular analyses revealed that enalapril treatment increases neuropeptide Y (NPY and cocaine- and amphetamine-regulated transcript (CART gene expression in hypothalamus, fatty acid synthase (FAS and hormone-sensitive lipase (HSL gene expression in retroperitoneal WAT and decreases peroxixome proliferators-activated receptor (PPAR γ, PPARα, uncoupling protein (UCP 2 and UCP3 gene expression in WAT. The results of the current study indicate that enalapril administration during early postnatal development increases body mass, adiposity and serum lipids in adulthood associated with enhanced food intake and decreased metabolic activity in WAT, predisposing to obesity in adulthood.

  20. Early pharmacological inhibition of angiotensin-I converting enzyme activity induces obesity in adulthood.

    Science.gov (United States)

    de Picoli Souza, Kely; da Silva, Elton D; Batista, Elice C; Reis, Felipe C G; Silva, Sylvia M A; Castro, Charlles H M; Luz, Jaqueline; Pesquero, Jorge L; Dos Santos, Edson L; Pesquero, João B

    2015-01-01

    We have investigated early programming of body mass in order to understand the multifactorial etiology of obesity. Considering that the renin-angiotensin system (RAS) is expressed and functional in the white adipose tissue (WAT) and modulates its development, we reasoned whether early transitory inhibition of angiotensin-I converting enzyme activity after birth could modify late body mass development. Therefore, newborn Wistar rats were treated with enalapril (10 mg/kg of body mass) or saline, starting at the first day of life until the age of 16 days. Between days ninetieth and hundred and eightieth, a group of these animals received high fat diet (HFD). Molecular, biochemical, histological, and physiological data were collected. Enalapril treated animals presented hyperphagia, overweight, and increased serum level of triglycerides, total cholesterol and leptin, in adult life. Body composition analyses revealed higher fat mass with increased adipocyte size in these animals. Molecular analyses revealed that enalapril treatment increases neuropeptide Y (NPY) and cocaine- and amphetamine-regulated transcript (CART) gene expression in hypothalamus, fatty acid synthase (FAS), and hormone-sensitive lipase (HSL) gene expression in retroperitoneal WAT, and decreases peroxixome proliferators-activated receptor (PPAR)γ, PPARα, uncoupling protein (UCP)2, and UCP3 gene expression in WAT. The results of the current study indicate that enalapril administration during early postnatal development increases body mass, adiposity and serum lipids in adulthood associated with enhanced food intake and decreased metabolic activity in WAT, predisposing to obesity in adulthood.

  1. Control of modular multilevel converters for grid integration of full-scale wind energy conversion systems

    Science.gov (United States)

    Debnath, Suman

    The growing demand for wind power generation has pushed the capacity of wind turbines towards MW power levels. Higher capacity of the wind turbines necessitates operation of the generators and power electronic conversion systems at higher voltage/power levels. The power electronic conversion system of a wind energy conversion system (WECS) needs to meet the stringent requirements in terms of reliability, efficiency, scalability and ease of maintenance, power quality, and dv/dt stress on the generator/transformer. Although the multilevel converters including the neutral point clamped (NPC) converter and the active NPC converter meet most of the requirements, they fall short in reliability and scalability. Motivated by modularity/scalability feature of the modular multilevel converter (MMC), this research is to enable the MMC to meet all of the stringent requirements of the WECS by addressing their unique control challenges. This research presents systematic modeling and control of the MMC to enable it to be a potential converter topology for grid integration of full-scale WECSs. Based on the developed models, appropriate control systems for control of circulating current and capacitor voltages under fixed- and variable-frequency operations are proposed. Using the developed MMC models, a gradient-based cosimulation algorithm to optimize the gains of the developed control systems, is proposed. Performance/effectiveness of the developed models and the proposed control systems for the back-to-back MMC-based WECS are evaluated/verified based on simulations studies in the PSCAD/EMTDC software environment and experimental case studies on a laboratory-scale hardware prototype.

  2. NREL Pyrheliometer Comparisons: September 22-26, 2014 (NPC-2014)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.; Dooraghi, M.; Habte, A.

    2014-10-01

    Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for developing and deploying solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations that are traceable to an international standard is the first step in producing research-quality solar irradiance measurements. As with all measurement systems, absolute cavity radiometers and other types of pyrheliometers are subject to performance changes over time. NREL has developed and maintained a select group of absolute cavity radiometers with direct calibration traceability to the World Radiometric Reference (WRR), and uses these reference instruments to calibrate pyrheliometers and pyranometers using the ISO 17025 accredited Broadband Outdoor Radiometer Calibration (BORCAL) process. National Renewable Energy Laboratory (NREL) pyrheliometer comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owners and operators, each NPC provides an opportunity to determine the unique WRR transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the WRR. NPC-2014 was held September 22-26, 2014. Participants operated 36 absolute cavity radiometers and 22 conventional thermopile-based pyrheliometers to simultaneously measure clear-sky direct normal solar irradiance during this period, and this report documents the findings.

  3. Angiotensin converting enzyme (ACE) inhibitory, antihypertensive and antihyperlipidaemic activities of protein hydrolysates from Rhopilema esculentum.

    Science.gov (United States)

    Liu, Xin; Zhang, Miansong; Zhang, Chao; Liu, Changheng

    2012-10-15

    Angiotensin-converting enzyme (ACE) inhibitory, antihypertensive and antihyperlipidaemic activities of protein hydrolysates (RPH) from the jellyfish Rhopilema esculentum were investigated. R. esculentum was hydrolysed sequentially with pepsin and papain, and then the hydrolysate was ultrafiltered with a 2000 Da cut-off membrane. It was found that RPH contained high levels of Gly, Glu, Pro, Asp and Ala, having potential ACE inhibitory activity in vitro with an IC(50) of 1.28 mg/ml. It was also found that systolic blood pressure was reduced markedly in spontaneously hypertensive rats after single and chronic oral administration of RPH, indicating that RPH had an antihypertensive effect. In addition, oral administration of RPH decreased total serum cholesterol and triglyceride, and increased high-density lipoprotein cholesterol in rats fed with high-fat diet. These results indicate that RPH may prove to be a promising functional food for the prevention and treatment of hypertension and hyperlipidaemia. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Increasing brain angiotensin converting enzyme 2 activity decreases anxiety-like behavior in male mice by activating central Mas receptors.

    Science.gov (United States)

    Wang, Lei; de Kloet, Annette D; Pati, Dipanwita; Hiller, Helmut; Smith, Justin A; Pioquinto, David J; Ludin, Jacob A; Oh, S Paul; Katovich, Michael J; Frazier, Charles J; Raizada, Mohan K; Krause, Eric G

    2016-06-01

    Over-activation of the brain renin-angiotensin system (RAS) has been implicated in the etiology of anxiety disorders. Angiotensin converting enzyme 2 (ACE2) inhibits RAS activity by converting angiotensin-II, the effector peptide of RAS, to angiotensin-(1-7), which activates the Mas receptor (MasR). Whether increasing brain ACE2 activity reduces anxiety by stimulating central MasR is unknown. To test the hypothesis that increasing brain ACE2 activity reduces anxiety-like behavior via central MasR stimulation, we generated male mice overexpressing ACE2 (ACE2 KI mice) and wild type littermate controls (WT). ACE2 KI mice explored the open arms of the elevated plus maze (EPM) significantly more than WT, suggesting increasing ACE2 activity is anxiolytic. Central delivery of diminazene aceturate, an ACE2 activator, to C57BL/6 mice also reduced anxiety-like behavior in the EPM, but centrally administering ACE2 KI mice A-779, a MasR antagonist, abolished their anxiolytic phenotype, suggesting that ACE2 reduces anxiety-like behavior by activating central MasR. To identify the brain circuits mediating these effects, we measured Fos, a marker of neuronal activation, subsequent to EPM exposure and found that ACE2 KI mice had decreased Fos in the bed nucleus of stria terminalis but had increased Fos in the basolateral amygdala (BLA). Within the BLA, we determined that ∼62% of GABAergic neurons contained MasR mRNA and expression of MasR mRNA was upregulated by ACE2 overexpression, suggesting that ACE2 may influence GABA neurotransmission within the BLA via MasR activation. Indeed, ACE2 overexpression was associated with increased frequency of spontaneous inhibitory postsynaptic currents (indicative of presynaptic release of GABA) onto BLA pyramidal neurons and central infusion of A-779 eliminated this effect. Collectively, these results suggest that ACE2 may reduce anxiety-like behavior by activating central MasR that facilitate GABA release onto pyramidal neurons within the

  5. Robust Active Damping Control of LCL Filtered Grid Connected Converter Based Active Disturbance Rejection Control

    DEFF Research Database (Denmark)

    Abdeldjabar, Benrabah; Xu, Dianguo; Wang, Xiongfei

    2016-01-01

    This paper deals with the problem of LCL filter resonance in grid connected inverter control. The system equations are reformulated to allow the application of the active disturbance rejection control (ADRC). The resonance, assumed unknown, is treated as a disturbance, then estimated and mitigated....... By using this new robust control, a high level of performance is achieved with a minimum complexity in the controller design, and without any adaptive algorithm. It is demonstrated that the true quality of the control system is obtained by the proposed solution. Furthermore, it is shown that this control...... is robust against parameter variations and disturbances....

  6. A Novel Neutral Point Voltage Control Strategy for Three-Level NPC APF Based on SVPWM

    Directory of Open Access Journals (Sweden)

    Yao Xiaolong

    2015-01-01

    Full Text Available The unbalance of the neutral point voltage is an inherent problem of three-level neutral-point-clamped (NPC Active Power Filter (APF; this paper analyzes the causes of unbalanced neutral point voltage and studies the reason of the unbalance of the neutral point voltage. A novel neutral point voltage control strategy using Space Vector Pulse Width Modulation (SVPWM is proposed. The proposed strategy is based on the traditional SVPWM, by controlling the effect time of small vector, which can change the state of the midpoint voltage fluctuation, and the neutral point voltage can be maintained balance. The influence of the vector on neutral point balance is investigated in depth. Simulation results show the neutral point voltage balancing control strategy based on SPWM is effective.

  7. Quantitative retention-activity relationship models of angiotensin converting enzyme inhibitors using biopartitioning micellar chromatography.

    Science.gov (United States)

    Wang, Shu-Rong; Chen, Cong; Xiong, Mei-Jin; Wu, Li-Ping; Ye, Li-Ming

    2010-02-01

    Biopartitioning micellar chromatography (BMC) is a mode of micellar liquid chromatography that uses micellar mobile phases of Brij35 under adequate experimental conditions and can simulate biopartioning process of many kinds of drugs and describe their biological behavior. The capability of BMC to describe and estimate pharmacokinetic and pharmacodynamic parameters of angiotensin-converting enzyme inhibitors (ACEIs) had been studied in this paper. The correlation between retention factors of ACEIs obtained using BMC and bioactivity parameters (half-life, volume of distribution, clearance, and IC(50)) was investigated utilizing a second-order polynomial model. The P-values obtained for half-life, volume of distribution, clearance, and IC(50) models were less than 0.05, and the r(2) of those four models were 0.89, 0.98, 0.94, and 0.97, with r(2)(adj) (adjusted for freedom degrees) being 0.85, 0.98, 0.91, and 0.95, respectively. The predictive and interpretative ability of the chromatographic models was evaluated in terms of cross-validated data [root mean squared error of calibration (RMSEC), root mean squared error of cross-validation (leave-one-out) (RMSECV), and root mean squared error of cross-validation (leave-one-out) for interpolated data (RMSECVi)]. The quantitative retention-activity relationship (QRAR) models of ACEIs developed in this paper may be a useful approach to screening new chemicals in the early stage of development.

  8. Enzymatic activity of two caspases related to interleukin-1beta-converting enzyme.

    Science.gov (United States)

    Fassy, F; Krebs, O; Rey, H; Komara, B; Gillard, C; Capdevila, C; Yea, C; Faucheu, C; Blanchet, A M; Miossec, C; Diu-Hercend, A

    1998-04-01

    Interleukin-1beta-converting enzyme is a member of a family of human cysteine proteases with specificity for aspartic acid, which have been named caspases. Within this family of enzymes, transcript X (TX) and transcript Y (TY) (caspases 4 and 5, respectively) are very similar to ICE (caspase 1) and form the ICE subfamily. Given the high degree of conservation in the sequences of these proteases (more than 50% amino acid identity in the mature enzymes), it was of interest to examine whether they shared similar substrate specificities. The three enzymes, ICE, TX and TY, were therefore expressed in baculovirus-infected insect cells, as 30-kDa proteins lacking the propeptide. Automaturation into p20 and p10 subunits occurred within the cells. Active ICE, TX and TY were collected in the cell culture supernatants. In addition, their production induced the activation of an endogenous 32-kDa putative cysteine protease (CPP32) like caspase. T7-tagged ICE, TX and TY were purified by immunoaffinity and tested for their catalytic efficiency on YVAD-containing synthetic substrates and on the ICE natural substrate, pro-interleukin-1beta. TX cleaved the same synthetic substrates as ICE (Km of 90 microM and k(cat) of 0.4 s(-1) for Suc-YVAD-NH-Mec, where Suc represents succinyl and NH-Mec represents amino-4-methylcoumarin) and could cleave pro-interleukin-1beta into the same peptides as ICE but less efficiently. On the other hand, TY showed very little efficacy on the different ICE substrates (Km of 860 microM for Suc-YVAD-NH-Mec). These results show that the ICE/TX/TY subfamily has functional heterogeneity and that ICE remains the preferred enzyme for pro-interleukin-1beta cleavage.

  9. A Design of a New Column-Parallel Analog-to-Digital Converter Flash for Monolithic Active Pixel Sensor

    OpenAIRE

    Chakir, Mostafa; Akhamal, Hicham; Qjidaa, Hassan

    2017-01-01

    The CMOS Monolithic Active Pixel Sensor (MAPS) for the International Linear Collider (ILC) vertex detector (VXD) expresses stringent requirements on their analog readout electronics, specifically on the analog-to-digital converter (ADC). This paper concerns designing and optimizing a new architecture of a low power, high speed, and small-area 4-bit column-parallel ADC Flash. Later in this study, we propose to interpose an S/H block in the converter. This integration of S/H block increases the...

  10. Reduced VLDL clearance in Apoe−/−Npc1−/− mice is associated with increased Pcsk9 and Idol expression and decreased hepatic LDL-receptor levels

    Science.gov (United States)

    Ishibashi, Minako; Masson, David; Westerterp, Marit; Wang, Nan; Sayers, Scott; Li, Rong; Welch, Carrie L.; Tall, Alan R.

    2010-01-01

    Niemann-Pick type C1 (NPC1) promotes the transport of LDL receptor (LDL-R)-derived cholesterol from late endosomes/lysosomes to other cellular compartments. NPC1-deficient cells showed impaired regulation of liver_X receptor (LXR) and sterol regulatory element-binding protein (SREBP) target genes. We observed that Apoe−/−Npc1−/− mice displayed a marked increase in total plasma cholesterol mainly due to increased VLDL, reflecting decreased clearance. Although nuclear SREBP-2 and Ldlr mRNA levels were increased in Apoe−/−Npc1−/− liver, LDL-R protein levels were decreased in association with marked induction of proprotein convertase subtilisin/kexin type 9 (Pcsk9) and inducible degrader of the LDL-R (Idol), both known to promote proteolytic degradation of LDL-R. While Pcsk9 is known to be an SREBP-2 target, marked upregulation of IDOL in Apoe−/−Npc1−/− liver was unexpected. However, several other LXR target genes also increased in Apoe−/−Npc1−/− liver, suggesting increased synthesis of endogenous LXR ligands secondary to activation of sterol biosynthesis. In conclusion, we demonstrate that NPC1 deficiency has a major impact on VLDL metabolism in Apoe−/− mice through modulation of hepatic LDL-R protein levels. In contrast to modest induction of hepatic IDOL with synthetic LXR ligands, a striking upregulation of IDOL in Apoe−/−Npc1−/− mice could indicate a role of endogenous LXR ligands in regulation of hepatic IDOL. PMID:20562239

  11. Development of Buck-Type Single-Phase to Three-Phase Power Converter with Active Buffer

    Science.gov (United States)

    Ohnuma, Yoshiya; Itoh, Jun-Ichi

    This paper proposes a novel single-phase to three-phase power converter that can reduce the capacitance value of the smoothing capacitor in the DC link part. In the case of the single-phase converter, a large smoothing capacitor is required to absorb a power ripple with a frequency twice that of the power supply. The proposed method involves the use of an indirect matrix converter with an active snubber to absorb the power ripple. Therefore, the proposed system does not require a reactor and large energy buffer, such as a smoothing capacitor. Moreover, a diode bridge can be used on the rectifier stage in the proposed circuit. In this paper, the basic operation and validity of the proposed method are confirmed by simulation and experiment result. Thus, it is confirmed that good waveforms for input and output currents can be obtained by the proposed method.

  12. Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber

    Science.gov (United States)

    Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

    2014-04-01

    Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

  13. Assaying nonspecific phospholipase C activity

    OpenAIRE

    Pejchar, P. (Přemysl); Günther, F.E.S.; Martinec, J. (Jan)

    2013-01-01

    Plant nonspecific phospholipase C (NPC) is a recently described enzyme which plays a role in membrane rearrangement during phosphate starvation. It is also involved in responses of plants to brassinolide, abscisic acid (ABA), elicitors, and salt. The NPC activity is decreased in cells treated with aluminum. In the case of salt stress, the molecular mechanism of NPC action is based on accumulation of diacylglycerol (DAG) by hydrolysis of phospholipids and conversion of DAG, the product of NPC ...

  14. NREL Pyrheliometer Comparison: September 16 to 27, 2013 (NPC-2013)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.; Dooraghi, M.; Habte, A.

    2013-11-01

    Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for the development and deployment of solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations traceable to an international standard is the first step in producing research-quality solar irradiance measurements. As with all measurement systems, absolute cavity radiometers and other types of pyrheliometers are subject to performance changes over time. NREL has developed and maintained a group of absolute cavity radiometers with direct calibration traceability to the World Radiometric Reference (WRR). These reference instruments are used by NREL to calibrate pyrheliometers and pyranometers using the ISO 17025 accredited Broadband Outdoor Radiometer Calibration (BORCAL) process (Reda et al. 2008). NPCs are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owners/operators, e.g. NREL, NASA, NIST, NOAA, USA industry and academia, USA-DOE and other national laboratories, and national and international organizations. Each NPC provides an opportunity to determine the unique World Radiometric Reference (WRR) transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the International System of Units through WRR.

  15. Fault Tolerant Operation of ISOP Multicell Dc-Dc Converter Using Active Gate Controlled SiC Protection Switch

    OpenAIRE

    Yusuke Hayashi; Yoshikatsu Matsugaki; Tamotsu Ninomiya

    2016-01-01

    An active gate controlled semiconductor protection switch using SiC-MOSFET is proposed to achieve the fault tolerant operation of ISOP (Input Series and Output Parallel) connected multicell dc-dc converter. The SiC-MOSFET with high temperature capability simplifies the configuration of the protection circuit, and its on-resistance control by the active gate controller realizes the smooth protection without the voltage and the current surges. The first laboratory prototype of the protection sw...

  16. Understanding the interplay between host immunity and Epstein-Barr virus in NPC patients

    Science.gov (United States)

    Shen, Yong; Zhang, Suzhan; Sun, Ren; Wu, Tingting; Qian, Jing

    2015-01-01

    Epstein-Barr virus (EBV) has been used as a paradigm for studying host–virus interactions, not only because of its importance as a human oncogenic virus associated with several malignancies including nasopharyngeal carcinoma (NPC) but also owing to its sophisticated strategies to subvert the host antiviral responses. An understanding of the interplay between EBV and NPC is critical for the development of EBV-targeted immunotherapy. Here, we summarize the current knowledge regarding the host immune responses and EBV immune evasion mechanisms in the context of NPC. PMID:26038769

  17. Single-current-sensor-based active front-end-converter-fed four ...

    Indian Academy of Sciences (India)

    /fulltext/sadh/042/08/1275-1283 ... The vector control analogy of the back to back converters is highlighted along with the experimental results of field-oriented control of induction machine using a dsPIC30F6010A digital signal controller.

  18. A Tapped-Inductor Buck-Boost Converter for a Dielectric ElectroActive Polymer Generator

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Munk-Nielsen, Stig

    2014-01-01

    of commercially-available, high-efficient, high-voltage, low-power semiconductor devices. In this paper, a high-efficient bidirectional tapped-inductor buck-boost converter, addressing high step-up and high step-down voltage conversion ratios, is proposed for energy harvesting applications based on DEAP...

  19. Lignocellulose-converting enzyme activity profiles correlate with molecular systematics and phylogeny grouping in the incoherent genus Phlebia (Polyporales, Basidiomycota).

    Science.gov (United States)

    Kuuskeri, Jaana; Mäkelä, Miia R; Isotalo, Jarkko; Oksanen, Ilona; Lundell, Taina

    2015-10-19

    The fungal genus Phlebia consists of a number of species that are significant in wood decay. Biotechnological potential of a few species for enzyme production and degradation of lignin and pollutants has been previously studied, when most of the species of this genus are unknown. Therefore, we carried out a wider study on biochemistry and systematics of Phlebia species. Isolates belonging to the genus Phlebia were subjected to four-gene sequence analysis in order to clarify their phylogenetic placement at species level and evolutionary relationships of the genus among phlebioid Polyporales. rRNA-encoding (5.8S, partial LSU) and two protein-encoding gene (gapdh, rpb2) sequences were adopted for the evolutionary analysis, and ITS sequences (ITS1+5.8S+ITS2) were aligned for in-depth species-level phylogeny. The 49 fungal isolates were cultivated on semi-solid milled spruce wood medium for 21 days in order to follow their production of extracellular lignocellulose-converting oxidoreductases and carbohydrate active enzymes. Four-gene phylogenetic analysis confirmed the polyphyletic nature of the genus Phlebia. Ten species-level subgroups were formed, and their lignocellulose-converting enzyme activity profiles coincided with the phylogenetic grouping. The highest enzyme activities for lignin modification (manganese peroxidase activity) were obtained for Phlebia radiata group, which supports our previous studies on the enzymology and gene expression of this species on lignocellulosic substrates. Our study implies that there is a species-level connection of molecular systematics (genotype) to the efficiency in production of both lignocellulose-converting carbohydrate active enzymes and oxidoreductases (enzyme phenotype) on spruce wood. Thus, we may propose a similar phylogrouping approach for prediction of lignocellulose-converting enzyme phenotypes in new fungal species or genetically and biochemically less-studied isolates of the wood-decay Polyporales.

  20. Design of a Modular Multilevel Converter as an Active Front-End for a magnet supply application

    CERN Document Server

    Panagiotis, Asimakopoulos; Massimo, Bongiorno

    2015-01-01

    The aim of this work is to describe the general design procedure of a Modular Multilevel Converter (MMC) applied as an Active Front-End (AFE) for a magnet supply for beam accelerators. The dimensioning criteria for the converter and the dc-link capacitance are presented and the grid transformer requirements are set. Considering the converter design, the arm inductance calculation is based on the specifications for the arm-current ripple and the DC-link fault tolerance, but, also, on the limitation of the second harmonic and the second-order LC resonance of the arm current. The module capacitance value is evaluated by focusing on the required switching dynamics and the capacitor-voltage ripple according to a newly proposed graphical method. The loading of each semiconductor in the half bridge is calculated via simulation, indicating the unsymmetrical current distribution. It is concluded that the current distribution for each semiconductor depends on the mode of operation of the converter. The different criter...

  1. A Design of a New Column-Parallel Analog-to-Digital Converter Flash for Monolithic Active Pixel Sensor.

    Science.gov (United States)

    Chakir, Mostafa; Akhamal, Hicham; Qjidaa, Hassan

    2017-01-01

    The CMOS Monolithic Active Pixel Sensor (MAPS) for the International Linear Collider (ILC) vertex detector (VXD) expresses stringent requirements on their analog readout electronics, specifically on the analog-to-digital converter (ADC). This paper concerns designing and optimizing a new architecture of a low power, high speed, and small-area 4-bit column-parallel ADC Flash. Later in this study, we propose to interpose an S/H block in the converter. This integration of S/H block increases the sensitiveness of the converter to the very small amplitude of the input signal from the sensor and provides a sufficient time to the converter to be able to code the input signal. This ADC is developed in 0.18  μ m CMOS process with a pixel pitch of 35  μ m. The proposed ADC responds to the constraints of power dissipation, size, and speed for the MAPS composed of a matrix of 64 rows and 48 columns where each column ADC covers a small area of 35 × 336.76  μ m 2 . The proposed ADC consumes low power at a 1.8 V supply and 100 MS/s sampling rate with dynamic range of 125 mV. Its DNL and INL are 0.0812/-0.0787 LSB and 0.0811/-0.0787 LSB, respectively. Furthermore, this ADC achieves a high speed more than 5 GHz.

  2. NREL Pyrheliometer Comparisons (NPC-2002), September 23 - October 4, 2002, Golden, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.; Stoffel, T.; Wilcox, S.

    2003-09-01

    NREL Pyrheliometer Comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owner/operators, the NPC provides an opportunity to determine the unique WRR transfer factor for each participating pyrheliometer.

  3. Results of NREL Pyrheliometer Comparisons (NPC1999), October 4-10, 1999, Golden, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.; Stoffel, T.; Wilcox, S.

    2000-09-01

    NREL Pyrheliometer Comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owner/operators, the NPC provides an opportunity to determine the unique WRR transfer factor for each participating pyrheliometer.

  4. NREL Pyrheliometer Comparisons (NPC-2001), September 24 - October 5, 2001, Golden, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.; Stoffel, T.; Wilcox, S.

    2003-09-01

    NREL Pyrheliometer Comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owner/operators, the NPC provides an opportunity to determine the unique WRR transfer factor for each participating pyrheliometer.

  5. NREL Pyrheliometer Comparisons (NPC-2003), September 22 - October 3, 2003, Golden, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Stoffel, T.; Reda, I.; Wilcox, S.

    2004-07-01

    NREL Pyrheliometer Comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owner/operators, the NPC provides an opportunity to determine the unique WRR transfer factor for each participating pyrheliometer.

  6. The Impact of a Power Electronics Converter in Phase Failure Work on the Power System Network

    Directory of Open Access Journals (Sweden)

    Dariusz Zieliński

    2016-09-01

    Full Text Available The paper presents the impact of phase failure work on power converters. The study includes a three-level NPC inverter (Neutral Point Clamped, controlled by Voltage Oriented Control (VOC. The NPC converter integrates renewable energy sources with the power grid. The article includes a discussion about the causes of phase failure work and an analysis of the converter’s failure and its impact on the power grid. The simulations were performed in MATLAB/Simulink. The study also includes the concept of an integrated protection for IGBTs, controlled by the DSP microprocessor system.

  7. Associations between HLA Class I alleles and the prevalence of nasopharyngeal carcinoma (NPC) among Tunisians

    Science.gov (United States)

    Li, Xin; Ghandri, Nahla; Piancatelli, Daniela; Adams, Sharon; Chen, Deborah; Robbins, Fu-Meei; Wang, Ena; Monaco, Alessandro; Selleri, Silvia; Bouaouina, Noureddine; Stroncek, David; Adorno, Domenico; Chouchane, Lotfi; Marincola, Francesco M

    2007-01-01

    The high prevalence of nasopharyngeal cancer (NPC) in Southern Asia and Mediterranean Northern Africa suggests genetic predisposition among other factors. While Human Leukocyte Antigen (HLA) haplotypes have been conclusively associated with NPC predisposition in Asians, Northern African Maghrebians have been less intensely studied. However, low resolution serological methods identified weak positive associations with HLA-B5, B13 and B18 and a negative with HLA-B14. Using sequence based typing (SBT), we performed a direct comparison of HLA class I frequencies in a cohort of 136 Tunisian patients with NPC matched for gender, age and geographical residence to 148 normal Tunisians. The bimodal age distribution of NPC in Maghrebians was also taken into account. HLA frequencies in normal Tunisians were also compared with those of Northern Moroccan Berbers (ME) to evaluate whether the Tunisian population in this study could be considered representative of other Maghrebian populations. HLA-B14 and -Cw08 were negatively associated with NPC (odd ratio = 0.09 and 0.18 respectively, Fisher p2-value = 0.0001 and = 0.003). Moreover, positive associations were observed for HLA-B-18, -B51 (split of -B5) and -B57 (p2-value < 0.025 in all) confirming previous findings in Maghrebs. The HLA-B14/Cw*08 haplotype frequency (HF) was 0.007 in NPC patients compared to 0.057 in both Tunisian (OR = 0.12; p2-value = 0.001) and Moroccan controls. This study confirms several previous associations noted by serologic typing between HLA class I alleles and the prevalence of NPC in Maghrebians populations. In addition, we identified a putative haplotype rare in Tunisian patients with NPC that may serve as a genetic marker for further susceptibility studies. PMID:17480220

  8. Combination of proteasome and class I HDAC inhibitors induces apoptosis of NPC cells through an HDAC6-independent ER stress-induced mechanism.

    Science.gov (United States)

    Hui, Kwai Fung; Chiang, Alan K S

    2014-12-15

    The current paradigm stipulates that inhibition of histone deacetylase (HDAC) 6 is essential for the combinatorial effect of proteasome and HDAC inhibitors for the treatment of cancers. Our study aims to investigate the effect of combining different class I HDAC inhibitors (without HDAC6 action) with a proteasome inhibitor on apoptosis of nasopharyngeal carcinoma (NPC). We found that combination of a proteasome inhibitor, bortezomib, and several class I HDAC inhibitors, including MS-275, apicidin and romidepsin, potently induced killing of NPC cells both in vitro and in vivo. Among the drug pairs, combination of bortezomib and romidepsin (bort/romidepsin) was the most potent and could induce apoptosis at low nanomolar concentrations. The apoptosis of NPC cells was reactive oxygen species (ROS)- and caspase-dependent but was independent of HDAC6 inhibition. Of note, bort/romidepsin might directly suppress the formation of aggresome through the downregulation of c-myc. In addition, two markers of endoplasmic reticulum (ER) stress-induced apoptosis, ATF-4 and CHOP/GADD153, were upregulated, whereas a specific inhibitor of caspase-4 (an initiator of ER stress-induced apoptosis) could suppress the apoptosis. When ROS level in the NPC cells was reduced to the untreated level, ER stress-induced caspase activation was abrogated. Collectively, our data demonstrate a model of synergism between proteasome and class I HDAC inhibitors in the induction of ROS-dependent ER stress-induced apoptosis of NPC cells, independent of HDAC6 inhibition, and provide the rationale to combine the more specific and potent class I HDAC inhibitors with proteasome inhibitors for the treatment of cancers. © 2014 UICC.

  9. IMPLEMENTASI KLASIFIKASI BAYESIAN UNTUK STRATEGI MENYERANG JARAK DEKAT PADA NPC (NON PLAYER CHARACTERMENGGUNAKAN UNITY 3D

    Directory of Open Access Journals (Sweden)

    Siti Asmiatun

    2016-06-01

    Full Text Available Abstract—Dalam sebuah game strategi penyerangan untuk melawan musuh harus diterapkan, sehingga lebih menarik pemain game untuk menyelesaikan permainan sampai dengan tujuan yang akan dicapai. Penelitian ini membahas tentang strategi menyerang jarak dekat untuk NPC (Non Player Character. Dalam sebuah game khususnya untuk game FPS (First Person Shooter, dibutuhkan suatu strategi NPC, dengan tujuan untuk membuat game menjadi lebih atraktif dan realistik. Strategi menyerang dalam penelitian ini adalah membagi beberapa perilaku penyerangan NPC ketika berada pada posisi paling dekat dengan musuh. Penelitian ini menerapkan algoritma bayesian untuk klasifikasi perilaku penyerangan NPC tersebut. Klasifikasi tersebut diharapkan dapat meningkatkan strategi menyerang melawan musuh. Klasifikasi  penyerangan NPC dibiagi menjadi dua perilaku penyerangan yaitu perilaku memukul dan perilaku menggigit. Sedangkan untuk variabel yang digunakan dalam klasifikasi bayesian adalah health point, attack point player dan jarak yang diperoleh dari kondisi NPC. Dari hasil pengujian metode klasifikasi bayesian menggunakan pengujian confusion matrix, dengan percobaan permainan sebanyak 10 kali, telah  menghasilkan presentasi tingkat akurasi pada confusion matrix mencapai nilai persentase sebesar 80 %. Hal ini membubktikan bahwa klasifikasi perilaku penyerangan jarak dekat dengan metode klasifikasi bayesian dapat diterapkan dengan hasil yang baik.

  10. Ebola virus and severe acute respiratory syndrome coronavirus display late cell entry kinetics: evidence that transport to NPC1+ endolysosomes is a rate-defining step.

    Science.gov (United States)

    Mingo, Rebecca M; Simmons, James A; Shoemaker, Charles J; Nelson, Elizabeth A; Schornberg, Kathryn L; D'Souza, Ryan S; Casanova, James E; White, Judith M

    2015-03-01

    Ebola virus (EBOV) causes hemorrhagic fevers with high mortality rates. During cellular entry, the virus is internalized by macropinocytosis and trafficked through endosomes until fusion between the viral and an endosomal membrane is triggered, releasing the RNA genome into the cytoplasm. We found that while macropinocytotic uptake of filamentous EBOV viruslike particles (VLPs) expressing the EBOV glycoprotein (GP) occurs relatively quickly, VLPs only begin to enter the cytoplasm after a 30-min lag, considerably later than particles bearing the influenza hemagglutinin or GP from lymphocytic choriomeningitis virus, which enter through late endosomes (LE). For EBOV, the long lag is not due to the large size or unusual shape of EBOV filaments, the need to prime EBOV GP to the 19-kDa receptor-binding species, or a need for unusually low endosomal pH. In contrast, since we observed that EBOV entry occurs upon arrival in Niemann-Pick C1 (NPC1)-positive endolysosomes (LE/Lys), we propose that trafficking to LE/Lys is a key rate-defining step. Additional experiments revealed, unexpectedly, that severe acute respiratory syndrome (SARS) S-mediated entry also begins only after a 30-min lag. Furthermore, although SARS does not require NPC1 for entry, SARS entry also begins after colocalization with NPC1. Since the only endosomal requirement for SARS entry is cathepsin L activity, we tested and provide evidence that NPC1(+) LE/Lys have higher cathepsin L activity than LE, with no detectable activity in earlier endosomes. Our findings suggest that both EBOV and SARS traffic deep into the endocytic pathway for entry and that they do so to access higher cathepsin activity. Ebola virus is a hemorrhagic fever virus that causes high fatality rates when it spreads from zoonotic vectors into the human population. Infection by severe acute respiratory syndrome coronavirus (SARS-CoV) causes severe respiratory distress in infected patients. A devastating outbreak of EBOV occurred in West

  11. Angiotensin-I Converting Enzyme (ACE Inhibitory and Anti-Oxidant Activities of Sea Cucumber (Actinopyga lecanora Hydrolysates

    Directory of Open Access Journals (Sweden)

    Raheleh Ghanbari

    2015-12-01

    Full Text Available In recent years, food protein-derived hydrolysates have received considerable attention because of their numerous health benefits. Amongst the hydrolysates, those with anti-hypertensive and anti-oxidative activities are receiving special attention as both activities can play significant roles in preventing cardiovascular diseases. The present study investigated the angiotensin-I converting enzyme (ACE inhibitory and anti-oxidative activities of Actinopyga lecanora (A. lecanora hydrolysates, which had been prepared by alcalase, papain, bromelain, flavourzyme, pepsin, and trypsin under their optimum conditions. The alcalase hydrolysate showed the highest ACE inhibitory activity (69.8% after 8 h of hydrolysis while the highest anti-oxidative activities measured by 2,2-diphenyl 1-1-picrylhydrazyl radical scavenging (DPPH (56.00% and ferrous ion-chelating (FIC (59.00% methods were exhibited after 24 h and 8 h of hydrolysis, respectively. The ACE-inhibitory and anti-oxidative activities displayed dose-dependent trends, and increased with increasing protein hydrolysate concentrations. Moreover, strong positive correlations between angiotensin-I converting enzyme (ACE inhibitory and anti-oxidative activities were also observed. This study indicates that A. lecanora hydrolysate can be exploited as a source of functional food owing to its anti-oxidant as well as anti-hypertension functions.

  12. Extraction temperature affects the activities of antioxidation, carbohydrate-digestion enzymes, and angiotensin-converting enzyme of Pleurotus citrinopileatus extract

    Directory of Open Access Journals (Sweden)

    Pao-Huei Chen

    2016-07-01

    Full Text Available Extraction temperature can potentially affect the chemical compositions and bioactivities of the extracts obtained. The objective of this study was to investigate the effect of extraction temperature on the distribution of bioactive compounds and the bioactivities of Pleurotus citrinopileatus. The antioxidant activities (2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid+ scavenging capabilities and the inhibitory capabilities on pancreatic α-amylase, intestinal α-glucosidase, and hypertension-linked angiotensin-converting enzyme of hot water P. citrinopileatus extract and cold water P. citrinopileatus extract were determined. The results showed that the antioxidant capabilities and inhibitory effects on α-amylase, α-glucosidase, and angiotensin-converting enzyme of cold water P. citrinopileatus extract were significantly higher than those of hot water P. citrinopileatus extract. The cold water P. citrinopileatus extracted was further precipitated with 100% ammonium sulfate to obtain a polysaccharide fraction or with 75% ethanol to obtain a protein fraction. The inhibitory activities of the protein fraction of the cold water P. citrinopileatus extract on α-amylase, α-glucosidase, and angiotensin-converting enzyme were significantly higher than those of the polysaccharide fraction. In conclusion, the protein fraction of the cold water P. citrinopileatus extract could be responsible for its bioactivities.

  13. NREL Pyrheliometer Comparisons: September 25-October 6, 2017 (NPC-2017)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, Ibrahim M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dooraghi, Michael R. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Andreas, Afshin M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Habte, Aron M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-11-07

    et al. 2008). National Renewable Energy Laboratory (NREL) pyrheliometer comparisons (NPCs) are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all ACR owners and operators, each NPC provides an opportunity to determine the unique WRR transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the WRR.

  14. Effects on plasma angiotensin-converting enzyme activity and circulating renin of lisinopril and enalapril alone and in combination with propranolol in healthy volunteers

    DEFF Research Database (Denmark)

    Hansen, Erik Feldager; Bendtsen, Flemming; Henriksen, Jens Henrik

    1999-01-01

    The effects on plasma angiotensin-converting enzyme activity and renin activity of the two long-acting angiotensin-converting enzyme inhibitors, lisinopril and enalapril, alone and in combination with propranolol were studied. In an open, randomised, cross-over design 12 healthy volunteers received...... orally enalapril 20 mg alone, enalapril 20 mg in combination with propranolol 80 mg, lisinopril 20 mg alone, and lisinopril 20 mg in combination with propranolol 80 mg. Plasma angiotensin-converting enzyme activity and plasma renin activity were measured for 24 h after each treatment period. Lisinopril...

  15. A Generic Topology Derivation Method for Single-phase Converters with Active Capacitive DC-links

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai; Zhu, Guorong

    2016-01-01

    capacitive DCDC- link solutions, but important aspects of the topology assess-ment, such as the total energy storage, overall capacitive energy buffer ratio, cost, and reliability are still not available. This paper proposes a generic topology derivation method of single-phase power converters...... with capacitive DC-links, which derives all existing topologies to our best knowledge, and identify a few new topologies. A reliability-oriented design process is applied to compare the cost of different solutions with the lifetime target of 10 years and 35 years, respectively. It reveals that the most cost...

  16. Combined Chemical Activation and Fenton Degradation to Convert Waste Polyethylene into High-Value Fine Chemicals.

    Science.gov (United States)

    Chow, Cheuk-Fai; Wong, Wing-Leung; Ho, Keith Yat-Fung; Chan, Chung-Sum; Gong, Cheng-Bin

    2016-07-04

    Plastic waste is a valuable organic resource. However, proper technologies to recover usable materials from plastic are still very rare. Although the conversion/cracking/degradation of certain plastics into chemicals has drawn much attention, effective and selective cracking of the major waste plastic polyethylene is extremely difficult, with degradation of C-C/C-H bonds identified as the bottleneck. Pyrolysis, for example, is a nonselective degradation method used to crack plastics, but it requires a very high energy input. To solve the current plastic pollution crisis, more effective technologies are needed for converting plastic waste into useful substances that can be fed into the energy cycle or used to produce fine chemicals for industry. In this study, we demonstrate a new and effective chemical approach by using the Fenton reaction to convert polyethylene plastic waste into carboxylic acids under ambient conditions. Understanding the fundamentals of this new chemical process provides a possible protocol to solve global plastic-waste problems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Angiotensin Converting Enzyme Inhibitory and Antioxidant Activities of Enzymatic Hydrolysates of Korean Native Cattle (Hanwoo Myofibrillar Protein

    Directory of Open Access Journals (Sweden)

    Seung Yun Lee

    2017-01-01

    Full Text Available The purpose of this study was to determine the angiotensin converting enzyme (ACE inhibitory and antioxidant activities of myofibrillar protein hydrolysates (HMPHs of different molecular weights (<3 and <10 kDa derived from Korean native cattle (Hanwoo breed using a commercially available and inexpensive enzyme (Alkaline-AK. HMPH of both tested molecular weights had ACE inhibitory activity. Among the antioxidant activities, iron chelation and nitrite scavenging activities were higher in low-molecular-weight peptide of HMPH (<3 kDa, whereas 2,2-diphenyl-1-picrylhydrazyl (DPPH radical scavenging activity was higher in high-molecular-weight peptide of HMPH (<10 kDa. HMPH did not induce cytotoxicity in RAW 264.7 cells at concentrations of 5–20 mg/mL. These results indicate that HMPH can be cheaply produced using Alkaline-AK and applied as a potential ACE inhibitor and antioxidant.

  18. Effects on plasma angiotensin-converting enzyme activity and circulating renin of lisinopril and enalapril alone and in combination with propranolol in healthy volunteers

    DEFF Research Database (Denmark)

    Hansen, EF; Bendtsen, F; Henriksen, Jens Henrik Sahl

    1999-01-01

    The effects on plasma angiotensin-converting enzyme activity and renin activity of the two long-acting angiotensin-converting enzyme inhibitors, lisinopril and enalapril, alone and in combination with propranolol were studied. In an open, randomised, cross-over design 12 healthy volunteers received...... orally enalapril 20 mg alone, enalapril 20 mg in combination with propranolol 80 mg, lisinopril 20 mg alone, and lisinopril 20 mg in combination with propranolol 80 mg. Plasma angiotensin-converting enzyme activity and plasma renin activity were measured for 24 h after each treatment period. Lisinopril.......05). Plasma renin activity increased almost ten times after ingestion of both angiotensin-converting enzyme inhibitors, but the effect lasted significantly longer after lisinopril than after enalapril. Beta-Adrenergic blockade blunted the effect on the increase in plasma renin activity induced by both...

  19. A Design of a New Column-Parallel Analog-to-Digital Converter Flash for Monolithic Active Pixel Sensor

    Directory of Open Access Journals (Sweden)

    Mostafa Chakir

    2017-01-01

    Full Text Available The CMOS Monolithic Active Pixel Sensor (MAPS for the International Linear Collider (ILC vertex detector (VXD expresses stringent requirements on their analog readout electronics, specifically on the analog-to-digital converter (ADC. This paper concerns designing and optimizing a new architecture of a low power, high speed, and small-area 4-bit column-parallel ADC Flash. Later in this study, we propose to interpose an S/H block in the converter. This integration of S/H block increases the sensitiveness of the converter to the very small amplitude of the input signal from the sensor and provides a sufficient time to the converter to be able to code the input signal. This ADC is developed in 0.18 μm CMOS process with a pixel pitch of 35 μm. The proposed ADC responds to the constraints of power dissipation, size, and speed for the MAPS composed of a matrix of 64 rows and 48 columns where each column ADC covers a small area of 35 × 336.76 μm2. The proposed ADC consumes low power at a 1.8 V supply and 100 MS/s sampling rate with dynamic range of 125 mV. Its DNL and INL are 0.0812/−0.0787 LSB and 0.0811/−0.0787 LSB, respectively. Furthermore, this ADC achieves a high speed more than 5 GHz.

  20. Catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Liber, B.

    1991-08-22

    A catalytic converter is provided which is economical to manufacture and is not readily poisoned by contaminants in a gas stream such as would be encountered in the operation of an internal combustion engine, whereby an improved life expectancy of the unit can be achieved. The converter of the invention comprises a sintered porous body including molybdenum or a molybdenum-containing compound or a molybdenum complex. A method of forming a catlytic converter unit comprises forming a slurry including molybdenum or a molybdenum compound, forming the slurry into a sintered body member, and hardening or curing the same to form a self-sustaining body member. A method for treating an exhaust gas using the above catalytic converter is also disclosed. A preferred embodiment for an internal combustion engine is described. Examples of different catalytic compositions are included. 13 figs.

  1. Photovoltaic power converter system with a controller configured to actively compensate load harmonics

    Science.gov (United States)

    de Rooij, Michael Andrew; Steigerwald, Robert Louis; Delgado, Eladio Clemente

    2008-12-16

    Photovoltaic power converter system including a controller configured to reduce load harmonics is provided. The system comprises a photovoltaic array and an inverter electrically coupled to the array to generate an output current for energizing a load connected to the inverter and to a mains grid supply voltage. The system further comprises a controller including a first circuit coupled to receive a load current to measure a harmonic current in the load current. The controller includes a second circuit to generate a fundamental reference drawn by the load. The controller further includes a third circuit for combining the measured harmonic current and the fundamental reference to generate a command output signal for generating the output current for energizing the load connected to the inverter. The photovoltaic system may be configured to compensate harmonic currents that may be drawn by the load.

  2. Active pixel sensor having intra-pixel charge transfer with analog-to-digital converter

    Science.gov (United States)

    Fossum, Eric R. (Inventor); Mendis, Sunetra K. (Inventor); Pain, Bedabrata (Inventor); Nixon, Robert H. (Inventor); Zhou, Zhimin (Inventor)

    2003-01-01

    An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node and an analog-to-digital converter formed in the substrate connected to the output of the readout circuit.

  3. [Statistical tests in medical research: traditional methods vs. multivariate NPC permutation tests].

    Science.gov (United States)

    Arboretti, Rosa; Bordignon, Paolo; Corain, Livio; Palermo, Giuseppe; Pesarin, Fortunato; Salmaso, Luigi

    2015-01-01

    Statistical tests in medical research: traditional methods vs. multivariate npc permutation tests.Within medical research, a useful statistical tool is based on hypotheses testing in terms of the so-called null, that is the treatment has no effect, and alternative hypotheses, that is the treatment has some effects. By controlling the risks of wrong decisions, empirical data are used in order to possibly reject the null hypotheses in favour of the alternative, so that demonstrating the efficacy of a treatment of interest. The multivariate permutation tests, based on the nonparametric combination - NPC method, provide an innovative, robust and effective hypotheses testing solution to many real problems that are commonly encountered in medical research when multiple end-points are observed. This paper discusses the various approaches to hypothesis testing and the main advantages of NPC tests, which consist in the fact that they require much less stringent assumptions than traditional statistical tests. Moreover, the related results may be extended to the reference population even in case of selection-bias, that is non-random sampling. In this work, we review and discuss some basic testing procedures along with the theoretical and practical relevance of NPC tests showing their effectiveness in medical research. Within the non-parametric methods, NPC tests represent the current "frontier" of statistical research, but already widely available in the practice of analysis of clinical data.

  4. Decreased NPC1L1 expression in the liver from Chinese female gallstone patients

    Directory of Open Access Journals (Sweden)

    Zhang Sheng-Dao

    2010-02-01

    Full Text Available Abstract Background Cholesterol gallstone disease is a very common disease in both industrialized and developing countries. Many studies have found that cholesterol gallstones are more common in women than men. The molecular mechanisms underlying the relationship between female gallstone disease and hepatic sterol transporters are still undergoing definition and have not been evaluated in humans. Aims The aim of this study is to probe for underlying hepatic molecular defects associated with development of gallstones in female. Methods/Results Fifty-seven nonobese, normolipidemic Chinese female gallstone patients (GS were investigated with 12 age- and body mass index-matched female gallstone-free controls (GSF. The bile from the female GS had higher cholesterol saturation than that from the female GSF. The hepatic NPC1L1 mRNA levels were lower in female GS, correlated with SREBP2 mRNA. NPC1L1 downregulation was confirmed at protein levels. Consistently, immunohistochemistry showed decreased NPC1L1 expression in female GS. Conclusions The decreased hepatic NPC1L1 levels in female GS might indicate a downregulated reabsorption of biliary cholesterol in the liver, which, in turn, leads to the cholesterol supersaturation of bile. Our data are consistent with the possibility that hepatic NPC1L1 may be mediated by SREBP2.

  5. Role of STARD4 and NPC1 in intracellular sterol transport.

    Science.gov (United States)

    Maxfield, Frederick R; Iaea, David B; Pipalia, Nina H

    2016-12-01

    Cholesterol plays an important role in determining the biophysical properties of membranes in mammalian cells, and the concentration of cholesterol in membranes is tightly regulated. Cholesterol moves among membrane organelles by a combination of vesicular and nonvesicular transport pathways, but the details of these transport pathways are not well understood. In this review, we discuss the mechanisms for nonvesicular sterol transport with an emphasis on the role of STARD4, a small, soluble, cytoplasmic sterol transport protein. STARD4 can rapidly equilibrate sterol between membranes, especially membranes with anionic lipid headgroups. We also discuss the sterol transport in late endosomes and lysosomes, which is mediated by a soluble protein, NPC2, and a membrane protein, NPC1. Homozygous mutations in these proteins lead to a lysosomal lipid storage disorder, Niemann-Pick disease type C. Many of the disease-causing mutations in NPC1 are associated with degradation of the mutant NPC1 proteins in the endoplasmic reticulum. Several histone deacetylase inhibitors have been found to rescue the premature degradation of the mutant NPC1 proteins, and one of these is now in a small clinical trial.

  6. Active Power and DC-link Voltage Coordinative Control for Cascaded DC-AC Converter with Bidirectional Power Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Chen, Zhe; Deng, Fujin

    2015-01-01

    Two stage cascaded converters are widely used in DC/AC hybrid systems to achieve the bidirectional power transmission. The topology of dual active bridge cascaded with inverter (DABCI) is commonly used in this application. This paper proposes a coordinative control method for DABCI and it’s able......, and this responsibility sharing control can effectively suppress the impact of the power variation on the DC-link voltage, without sacrificing stability. The proposed control method is also effective for DABCI in unidirectional power transmission. The effectiveness of the propose control has been validated by both...

  7. A Dual Active Bridge Converter with an Extended High-Efficiency Range by DC Blocking Capacitor Voltage Control

    DEFF Research Database (Denmark)

    Qin, Zian; Shen, Yanfeng; Loh, Poh Chiang

    2017-01-01

    A Dual Active Bridge (DAB) converter can achieve a wide high-efficiency range when its input and output voltages are equal, assuming a 1:1 turns ratio for its isolation transformer. If its input or output voltage is doubled, efficiency of the DAB will drop significantly, because of the introduction...... of hard switching and high circulating power. Thus, a new modulation scheme has been proposed, whose main idea is to introduce a voltage offset across the dc blocking capacitor connected in series with the transformer. Operational principle of the proposed modulation has been introduced, before analyzing...

  8. Self-commissioning notch filter for active damping in three phase LCL-filter based grid converters

    DEFF Research Database (Denmark)

    Alzola, Rafael Pena; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    LCL-filters are used to mitigate the harmonic current content in grid converters. The LCL-filter resonance must be damped in order to avoid stability problems in the current control. Active damping avoids resistors at the expense of increased control complexity. Large grid impedance variations can...... of exciting the LCL-filter. However, the notch filter tuning requires considerable design effort and the variations in the resonance frequency limit the LCL-filter robustness. This paper proposes a simple tuning procedure for the notch filter that results in proper robustness. In order to cope with the grid...

  9. (1)H NMR-Linked Metabolomics Analysis of Liver from a Mouse Model of NP-C1 Disease.

    Science.gov (United States)

    Ruiz-Rodado, Victor; Nicoli, Elena-Raluca; Probert, Fay; Smith, David A; Morris, Lauren; Wassif, Christopher A; Platt, Frances M; Grootveld, Martin

    2016-10-07

    Clinical manifestations of Niemann-Pick type C1 (NP-C1) disease include neonatal hepatosplenomegaly and in some patients progressive liver dysfunction and failure. This study involved a (1)H NMR-linked metabolomics analysis of liver samples collected from a NP-C1 disease mutant mouse model in order to explore time-dependent imbalances in metabolic pathways associated with NP-C1 liver dysfunction, including fibrosis. NP-C1 mutant (Npc1(-/-); NP-C1), control (Npc1(+/+); WT), and NP-C1 heterozygous mice (Npc1(+/-); HET) were generated from heterozygote matings. Aqueous extracts of these liver samples collected at time points of 3, 6, 9, and 11 weeks were subjected to high-resolution NMR analysis, and multivariate (MV) metabolomics analyses of data sets acquired were performed. A MV random forests (RFs) model effectively discriminated between NP-C1 and a combined WT/HET hepatic NMR profiles with very high predictive accuracy and reliability. Key distinguishing features included significant upregulations in the hepatic concentrations of phenylalanine, tyrosine, glutamate, lysine/ornithine, valine, threonine, and hypotaurine/methionine, and diminished levels of nicotinate/niacinamide, inosine, phosphoenolpyruvate, and 3-hydroxyphenylacetate. Quantitative pathway topological analysis confirmed that imbalances in tyrosine biosynthesis, and hepatic phenylalanine, tyrosine, glutamate/glutamine, and nicotinate/niacinamide metabolism were involved in the pathogenesis of NP-C1 disease-associated liver dysfunction/damage. (1)H NMR-linked metabolomics analysis provides valuable biomarker information regarding hepatic dysfunction or damage in NP-C1 disease.

  10. Control and dynamic analysis of a parallel-connected single active bridge DC-DC converter for DC-grid wind farm application

    DEFF Research Database (Denmark)

    Park, Kiwoo; Chen, Zhe

    2015-01-01

    This study presents a control strategy and its dynamic analysis of a high-power dc-dc converter, which is constructed with the parallel-connected single active bridge (SAB) dc-dc converters for dc-grid wind farm applications. The structural and operational characteristics of the SAB dc-dc convert...... for dc-grid wind farm applications, an input voltage control method based on the PI control will be introduced and the dynamics of the overall system will be analysed. The analysis results are to be verified by means of simulations and experiments.......This study presents a control strategy and its dynamic analysis of a high-power dc-dc converter, which is constructed with the parallel-connected single active bridge (SAB) dc-dc converters for dc-grid wind farm applications. The structural and operational characteristics of the SAB dc-dc converter...... have several advantages for high-power applications, and the modular concept of the parallel-connected converter is highly beneficial especially for offshore wind farm applications in terms of maintenance cost and fault tolerance. To justify the feasibility of the parallel-connected SAB dc-dc converter...

  11. Kinetic imaging of NPC1L1 and sterol trafficking between plasma membrane and recycling endosomes in hepatoma cells

    DEFF Research Database (Denmark)

    Hartwig Petersen, Nicole; Færgeman, Nils J; Yu, Liqing

    2008-01-01

    fluorescent protein (NPC1L1-EGFP) and cholesterol analogues in hepatoma cells. At steady state about 42% of NPC1L1 resided in the transferrin (Tf) positive, sterol enriched endocytic recycling compartment (ERC), while time-lapse microscopy demonstrated NPC1L1 traffic between plasma membrane and ERC....... Fluorescence recovery after photobleaching (FRAP) revealed rapid recovery (half-time t1/2 ~2.5 min) of about 35% of NPC1L1 in the ERC probably replenished from peripheral sorting endosomes. Acute cholesterol depletion blocked internalization of NPC1L1-EGFP and Tf and stimulated recycling of NPC1L1-EGFP from...... the ERC to the plasma membrane. NPC1L1-EGFP facilitated transport of fluorescent sterols from the plasma membrane to the ERC. Insulin induced translocation of vesicles containing NPC1L1 and fluorescent sterol from the ERC to the cell membrane. Upon polarization of hepatoma cells NPC1L1 resided almost...

  12. Angiotensin-I-Converting Enzyme Inhibitory and Antioxidant Activities of Protein Hydrolysate from Muscle of Barbel (Barbus callensis

    Directory of Open Access Journals (Sweden)

    Assaad Sila

    2013-01-01

    Full Text Available The present study investigated angiotensin-I-converting enzyme (ACE inhibitory and antioxidant activities of barbel muscle protein hydrolysate prepared with Alcalase. The barbel muscle protein hydrolysate displayed a high ACE inhibitory activity (CI50=0.92 mg/mL. The antioxidant activities of protein hydrolysate at different concentrations were evaluated using various in vitro antioxidant assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH radical method and reducing power assay. The barbel muscle protein hydrolysate exhibited an important radical scavenging effect and reducing power. These results obtained by in vitro systems obviously established the antioxidant potency of barbel hydrolysate to donate electron or hydrogen atom to reduce the free radical. Furthermore, these bioactive substances can be exploited into functional foods or used as source of nutraceuticals.

  13. Analysis and design of grid-current-feedback active damping for LCL resonance in grid-connected voltage source converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    in a digital control system. The instability induced by the negative virtual resistance, which is commonly experienced in the feedback-type active damping, can thus be avoided. A systematic design method of the highpass filter is also proposed by the help of root locus analysis in the discrete z-domain. Lastly......This paper investigates the active damping of LCL-filter resonance within single-loop grid current control of grid-connected voltage source converters. First, the basic analysis in the continuous s-domain reveals that the grid-current-feedback active damping forms a virtual impedance across...... the grid-side inductor, and the use of a high-pass filter with a negative sign shapes the virtual impedance by an RL damper paralleled by a negative inductance. It is further found that such a negative virtual inductance plays a critical role in mitigating the phase lag caused by the time delay...

  14. Grid-Current-Feedback Active Damping for LCL Resonance in Grid-Connected Voltage-Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2016-01-01

    This paper investigates active damping of LCL-filter resonance in a grid-connected voltage-source converter with only grid-current feedback control. Basic analysis in the s-domain shows that the proposed damping technique with a negative high-pass filter along its damping path is equivalent...... to adding a virtual impedance across the grid-side inductance. This added impedance is more precisely represented by a series RL branch in parallel with a negative inductance. The negative inductance helps to mitigate phase lag caused by time delays found in a digitally controlled system. The mitigation...... of phase-lag, in turn, helps to shrink the region of nonminimum-phase behavior caused by negative virtual resistance inserted unintentionally by most digitally implemented active damping techniques. The presented high-pass-filtered active damping technique with a single grid-current feedback loop is thus...

  15. Fault Tolerant Operation of ISOP Multicell Dc-Dc Converter Using Active Gate Controlled SiC Protection Switch

    Directory of Open Access Journals (Sweden)

    Yusuke Hayashi

    2016-01-01

    Full Text Available An active gate controlled semiconductor protection switch using SiC-MOSFET is proposed to achieve the fault tolerant operation of ISOP (Input Series and Output Parallel connected multicell dc-dc converter. The SiC-MOSFET with high temperature capability simplifies the configuration of the protection circuit, and its on-resistance control by the active gate controller realizes the smooth protection without the voltage and the current surges. The first laboratory prototype of the protection switch is fabricated by using a SiC-MOSFET with a high frequency buck chopper for the active gate controller. The effectiveness of the proposed protection switch is verified, taking the impact of the volume reduction into account.

  16. Open-circuit fault diagnosis for a grid-connected NPC inverter with unity Power Factor

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede; Lee, June-Seok

    2015-01-01

    This paper presents an open-circuit fault detection method for a grid-connected Neutral-Point Clamped (NPC) inverter. The open-circuit fault mainly occurs due to bonding wire failures like lift-off and crack in the power module where the thermal stress is major factor among the stresses that can...... lead to bond-wire failures. Under the grid-connected condition, it is impossible to identify the location of faulty switch by the conventional methods, which usually use the output currents as it has the same distortions in several fault cases. The clamping diode is also one of fragile component...... in the NPC inverter, but usually it is not considered. The proposed method identifies precisely the faulty location of switch and clamping diode without any additional hardware or complex calculations. The feasibility of the proposed fault detection method for the grid-connected NPC inverter is verified...

  17. Molecular screening for Epstein Barr virus (EBV) among Sudanese patients with nasopharyngeal carcinoma (NPC).

    Science.gov (United States)

    Ahmed, Hussain Gadelkarim; Suliman, Rania Saad Abdul Gader; El Aziz, Mohammed Siddig Abd; Alshammari, Fawaz D

    2015-01-01

    The aim of this study was to screen for the presence of Epstein Barr Virus (EBV) among Sudanese patients with Nasopharyngeal Carcinoma (NPC). In this study, 150 tissue samples that were previously diagnosed as having NPC were screened for the presence of EBV using Polymerase Chain Reaction (PCR). PCR was performed to amplify two viral genes; EBV nuclear antigen-4 (EBNA-4) and latent membrane protein-1 (LMP1). EBV genes were detected in 92/150 (61.3%) tissue samples. Of the 92 infected samples, 58/92 (63%) were found among males and 34/92 (37%) were among females. EBV is prevalent in the Sudan and responsible of the vast majority of cases of NPC.

  18. Antioxidant, Liver Protective and Angiotensin I-converting Enzyme Inhibitory Activities of Old Laying Hen Hydrolysate in Crab Meat Analogue.

    Science.gov (United States)

    Jin, Sang Keun; Choi, Jung Seok; Choi, Yeung Joon; Lee, Seung-Jae; Lee, Seung Yun; Hur, Sun Jin

    2016-12-01

    The purpose of this study was to evaluate the antioxidative activities of Crab meat analogue prepared with protein hydrolysates obtained from mechanically deboned chicken meat (MDCM) from spent laying hens. 2 , 2-diphenyl-1-picrylhydrazyl hydrate (DPPH) radical-scavenging activity was increased by adding MDCM hydrolysates during storage, and activity correlated with the concentration of DPPH added up to 6 weeks of storage. Hydroxyl radical-scavenging activity was increased in all analogues containing MDCM hydrolysates. At 0 days of storage, angiotensin I-converting enzyme (ACE)-inhibitory activity was increased by the addition of MDCM hydrolysates. Activity did not correlate after 6 weeks of storage, in which ACE-inhibitory activity was increased with low concentrations of MDCM hydrolysates, but no ACE-inhibitory activity was observed at higher concentrations. The liver-protecting activity of crab meat analogue was shown to be around 60% of the positive control; however, it was not significantly different among the samples during storage. These results support the use of MDCM as a source of health-promoting constituents in crab meat analogue.

  19. Antioxidant, Liver Protective and Angiotensin I-converting Enzyme Inhibitory Activities of Old Laying Hen Hydrolysate in Crab Meat Analogue

    Directory of Open Access Journals (Sweden)

    Sang Keun Jin

    2016-12-01

    Full Text Available The purpose of this study was to evaluate the antioxidative activities of Crab meat analogue prepared with protein hydrolysates obtained from mechanically deboned chicken meat (MDCM from spent laying hens. 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH radical-scavenging activity was increased by adding MDCM hydrolysates during storage, and activity correlated with the concentration of DPPH added up to 6 weeks of storage. Hydroxyl radical-scavenging activity was increased in all analogues containing MDCM hydrolysates. At 0 days of storage, angiotensin I-converting enzyme (ACE-inhibitory activity was increased by the addition of MDCM hydrolysates. Activity did not correlate after 6 weeks of storage, in which ACE-inhibitory activity was increased with low concentrations of MDCM hydrolysates, but no ACE-inhibitory activity was observed at higher concentrations. The liver-protecting activity of crab meat analogue was shown to be around 60% of the positive control; however, it was not significantly different among the samples during storage. These results support the use of MDCM as a source of health-promoting constituents in crab meat analogue.

  20. Characterization of Niemann-Pick Type C2 protein expression in multiple cancers using a novel NPC2 monoclonal antibody.

    Directory of Open Access Journals (Sweden)

    Yi-Jen Liao

    Full Text Available Niemann-Pick Type C2 (NPC2 plays an important role in the regulation of intracellular cholesterol homeostasis via direct binding with free cholesterol. However, little is known about the significance of NPC2 in cancer. In this study, we have pinpointed the impact of various different cancers on NPC2 expression. A series of anti-NPC2 monoclonal antibodies (mAbs with the IgG2a isotype were generated and peptide screening demonstrated that the reactive epitope were amino acid residues 31-40 of the human NPC2 protein. The specificity of these mAbs was confirmed by Western blotting using shRNA mediated knock-down of NPC2 in human SK-Hep1 cells. By immunohistochemical staining, NPC2 is expressed in normal kidney, liver, breast, colon, lung, esophageal, uterine cervical, pancreatic and stomach tissue. Strong expression of NPC2 was found in the distal and proximal convoluted tubule of kidney and the hepatocytes of liver. Normal esophageal, uterine cervical, pancreatic, stomach, breast, colon and lung tissue stained moderately to weakly. When compared to their normal tissue equivalents, NPC2 overexpression was observed in cancers of the breast, colon and lung. Regarding to breast cancer, NPC2 up-regulation is associated with estrogen receptor (-, progesterone receptor (- and human epidermal growth factor receptor (+. On the other hand, NPC2 was found to be down-regulated in renal cell carcinoma, liver cirrhosis and hepatoma tissues. By antigen-capture enzyme immunoassay ELISA, the serum NPC2 is increased in patients with cirrhosis and liver cancer. According to western blot data, the change of glycosylated pattern of NPC2 in serum is associated with cirrhosis and liver cancer. To the best of our knowledge, this is the first comprehensive immunohistochemical and serological study investigating the expression of NPC2 in a variety of different human cancers. These novel monoclonal antibodies should help with elucidating the roles of NPC2 in tumor

  1. Digital Realization of Capacitor-Voltage Feedback Active Damping for LCL-Filtered Grid Converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The capacitor voltage of an LCL-filter can also be used for active damping, if it is fed back for synchronization. By this way, an extra current sensor can be avoided. Compared with the existing active damping techniques designed with capacitor current feedback, the capacitor voltage feedback act...

  2. Accurate and Less-Disturbing Active Antiislanding Method Based on PLL for Grid-Connected Converters

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Agelidis, Vassilios G.; Teodorescu, Remus

    2010-01-01

    by this method is small compared to other active antiislanding methods, such as active frequency drift or frequency shift up/down. The method does not affect the zero crossing of the injected current, can be used to estimate the grid impedance, and is highly robust to different grid disturbances and stiffness...

  3. Data Converter

    NARCIS (Netherlands)

    Schinkel, Daniel; Nuijten, Petrus A.C.M.

    2005-01-01

    A data converter comprises a discrete- time sigma delta modulator e.g. for driving a Class-D power amplifier. The low-pass filter of the sigma delta modulator is modified by adding a suitably positioned pole to lower the oscillation frequency (limit cycle) of the sigma delta modulator in order to

  4. Data Converter

    NARCIS (Netherlands)

    Schinkel, Daniel

    2005-01-01

    A data converter comprises a discrete-time sigma delta modulator e.g. for driving a Class-D power amplifier. The low-pass filter of the sigma delta modulator is modified by adding a suitably positioned pole to lower the oscillation frequency (limit cycle) of the sigma delta modulator in order to

  5. Data Converter

    NARCIS (Netherlands)

    Schinkel, Daniel

    2006-01-01

    A data converter comprises a discrete-time sigma delta modulator e.g. for driving a Class-D power amplifier. The low-pass filter of the sigma delta modulator is modified by adding a suitably positioned pole to lower the oscillation frequency (limit cycle) of the sigma delta modulator in order to

  6. Design optimization of a high-power transformer for three-phase dual active bridge DC-DC converter for MVDC grids

    OpenAIRE

    Lee, Youngsil; Vakil, Gaurang; Feldman, Ralph; Goodman, Andrew; Wheeler, Patrick

    2016-01-01

    High-power DC-DC converter will be one of the essential technologies for the future DC grids. Especially, a three-phase dual-active bridge DC-DC (3DAB) Converter is highly suitable for high-power DC systems. Key component within this converter is the high power transformer operated at a medium frequency (MF) range. The design and optimization of this key component is presented in this paper. The transformer provides galvanic isolation from low voltage level to medium level or high voltage lev...

  7. Asymmetric power device rating selection for even temperature distribution in NPC inverter

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede

    2017-01-01

    A major drawback of the NPC inverter is an unequal power loss distribution among the power devices which leads to unequal temperature stress among them. Therefore, certain power devices experience higher temperature stress, which is the main cause of power device module failure and thus both the ...

  8. Matrix metalloproteinase-1 (MMP-1) rs1799750 polymorphism is associated with nasopharyngeal carcinoma (NPC) risk.

    Science.gov (United States)

    Cao, L; Li, P; Dong, L

    2017-10-31

    A few studies suggested that matrix metalloproteinase 1 (MMP-1) rs1799750 polymorphism was associated with nasopharyngeal carcinoma (NPC) risk. However, other studies did not confirm this result. Thus, we did this meta-analysis to evaluate the association between MMP-1 rs1799750 polymorphism and NPC risk. We searched PubMed and EMBASE. Five studies with 1497 cases and 1643 controls were included in this meta-analysis. Subjects with MMP-1 rs1799750 polymorphism had an decreased NPC risk (OR = 0.79; 95%CI, 0.69-0.91; P = 0.0007; I2 = 70%). In the subgroup analysis by smoking, a marginally significant association was found in non-smokers (OR = 0.73, 95% CI 0.52 - 1.04, P = 0.08; I2 = 0%) but not smokers (OR = 0.59, 95% CI 0.24 - 1.42, P = 0.24; I2 = 83%). In conclusion, this meta-analysis showed that MMP-1 rs1799750 polymorphism was significantly associated with NPC risk.

  9. National Renewable Energy Laboratory Pyrheliometer Comparisons: 24 September - 5 October 2012 (NPC-2012)

    Energy Technology Data Exchange (ETDEWEB)

    Stoffel, T.; Reda, I.

    2013-05-01

    The NREL Pyrheliometer Comparisons for 2012 (NPC-2012) were held at the Solar Radiation Research Laboratory in Golden, Colorado, from September 24 through October 5 for the purpose of transferring the World Radiometric Reference (WRR) to participating instrument. Twenty scientists and engineers operated 32 absolute cavity radiometers and 18 conventional thermopile-based pyrheliometers to simultaneously measure clear-sky direct normal irradiance during the comparisons. The transfer standard group of reference radiometers for NPC-2012 consisted of four NREL radiometers with direct traceability to the WRR, having participated in the Eleventh International Pyrheliometer Comparisons (IPC-XI) hosted by the World Radiation Center in the fall of 2010. As the result of NPC-2012, each participating absolute cavity radiometer was assigned a new WRR transfer factor, computed as the reference irradiance computed by the transfer standard group divided by the observed irradiance from the participating radiometer. The performance of the transfer standard group during NPC-2012 was consistent with previous comparisons, including IPC-XI. The measurement performance of the transfer standard group allowed the transfer of the WRR to each participating radiometer with an estimated uncertainty of +/- 0.33% with respect to the International System of Units.

  10. SOGI-based capacitor voltage feedback active damping in LCL-filtered grid converters

    DEFF Research Database (Denmark)

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    The capacitor voltage feedback active damping control is an attractive way to suppress LCL-filter resonance especially for the systems where the capacitor voltage is used for grid synchronization, since no extra sensors are added. The derivative is the core of the capacitor voltage feedback active...... damping control. However, in digital systems, the discrete implementation of the derivative suffers from noise amplification and accuracy issues. To overcome these drawbacks, this paper proposes a new derivative method based on Second-Order Generalized Integrator. Theoretical study shows that the proposed...

  11. A rat brain cytosolic N-methyltransferase(s) activity converting phosphorylethanolamine into phosphorylcholine.

    Science.gov (United States)

    Andriamampandry, C; Massarelli, R; Freysz, L; Kanfer, J N

    1990-09-14

    It had been previously speculated upon but never proved that the methylation of phosphorylethanolamine could contribute to the production of choline containing compounds. However, experimental evidence obtained with neuronal cultures was interpreted as showing that the stepwise methylation of phosphobases may be an important route for this biosynthesis. We demonstrate that cytosolic fraction from rat brain possesses a N-methyltransferase activity capable of methylating phosphorylethanolamine and its mono- and dimethyl-derivatives into phosphorylcholine. The level of activity detectable in rat liver cytosol is only 18% of that found in the brain cytosol.

  12. Constitutively active Notch1 converts cranial neural crest-derived frontonasal mesenchyme to perivascular cells in vivo

    Directory of Open Access Journals (Sweden)

    Sophie R. Miller

    2017-03-01

    Full Text Available Perivascular/mural cells originate from either the mesoderm or the cranial neural crest. Regardless of their origin, Notch signalling is necessary for their formation. Furthermore, in both chicken and mouse, constitutive Notch1 activation (via expression of the Notch1 intracellular domain is sufficient in vivo to convert trunk mesoderm-derived somite cells to perivascular cells, at the expense of skeletal muscle. In experiments originally designed to investigate the effect of premature Notch1 activation on the development of neural crest-derived olfactory ensheathing glial cells (OECs, we used in ovo electroporation to insert a tetracycline-inducible NotchΔE construct (encoding a constitutively active mutant of mouse Notch1 into the genome of chicken cranial neural crest cell precursors, and activated NotchΔE expression by doxycycline injection at embryonic day 4. NotchΔE-targeted cells formed perivascular cells within the frontonasal mesenchyme, and expressed a perivascular marker on the olfactory nerve. Hence, constitutively activating Notch1 is sufficient in vivo to drive not only somite cells, but also neural crest-derived frontonasal mesenchyme and perhaps developing OECs, to a perivascular cell fate. These results also highlight the plasticity of neural crest-derived mesenchyme and glia.

  13. Yeasts from Colombian Kumis as source of peptides with Angiotensin I converting enzyme (ACE) inhibitory activity in milk.

    Science.gov (United States)

    Chaves-López, Clemencia; Tofalo, Rosanna; Serio, Annalisa; Paparella, Antonello; Sacchetti, Giampiero; Suzzi, Giovanna

    2012-09-17

    This study investigated the possibility of using yeast strains in fermented milks to obtain products with high Angiotensin I-converting enzyme (ACE) inhibitory activity and low bitter taste. Ninety-three yeast strains isolated from Colombian Kumis in different geographic regions were molecularly identified, and their milk fermentation performances were determined. Molecular identification evidenced that Galactomyces geotrichum, Pichia kudriavzevii, Clavispora lusitaniae and Candida tropicalis, were the dominant species. Eighteen out of 93 strains produced fermented milk with ACE-inhibitory (ACEI) activity values ranging from 8.69 to 88.19%. Digestion of fermented milk samples by pepsin and pancreatin demonstrated an increase in ACEI activity, with C. lusitaniae KL4A as the best producer of ACEI peptides. Moreover, sensory analysis of the products containing the major ACE-inhibitory activity pointed out that P. kudriavzevii KL84A and Kluyveromyces marxianus KL26A could be selected as potential adjunct starter cultures in Kumis, since they made a considerable contribution to the ACE inhibitory activity and produced fermented milk without bitter taste. In this study we observed that Colombian Kumis can be an excellent vehicle for the isolation of yeasts with a potential to enhance bioactive peptides produced during milk fermentation. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Highly Accurate Derivatives for LCL-Filtered Grid Converter with Capacitor Voltage Active Damping

    DEFF Research Database (Denmark)

    Xin, Zhen; Loh, Poh Chiang; Wang, Xiongfei

    2016-01-01

    The middle capacitor voltage of an LCL-filter, if fed back for synchronization, can be used for active damping. An extra sensor for measuring the capacitor current is then avoided. Relating the capacitor voltage to existing popular damping techniques designed with capacitor current feedback would...

  15. Impedance Stability Assessment of Active Damping Strategies for LCL Grid-Connected Converters

    DEFF Research Database (Denmark)

    Diaz, Enrique Rodriguez; Quintero, Juan Carlos Vasquez; Guerrero, Josep M.

    2017-01-01

    The use of LCL filters is a well accepted solution to attenuate the harmonics created by the pulsewidth modulation (PWM). However, inherently LCL filters have a resonance region where the unwanted harmonics are amplified, which can compromise instability. Active damping strategies are implemented...

  16. Disease and patient characteristics in NP-C patients: findings from an international disease registry

    Directory of Open Access Journals (Sweden)

    Patterson Marc C

    2013-01-01

    Full Text Available Abstract Background Niemann-Pick disease type C (NP-C is a rare neurovisceral disease characterized by progressive neurodegeneration and premature death. We report data recorded at enrolment in an ongoing international NP-C registry initiated in September 2009 to describe disease natural history, clinical course and treatment experience of NP-C patients in clinical practice settings. Methods The NPC Registry is a prospective observational cohort study. Participating sites are encouraged to evaluate all consecutive patients with a confirmed diagnosis of NP-C, regardless of their treatment status. All patients undergo clinical assessments and medical care as determined by their physicians. Data are collected through a secure internet-based data collection system. Results As of 19th March, 2012, 163 patients have been enrolled in centres across 14 European countries, Australia, Brazil and Canada. The mean (SD age at enrolment was 19.6 (13.0 years. In general there was a long lag time between the mean (SD age at neurological onset (10.9 (9.8 years and age at diagnosis (15.0 (12.2 years. Among all enrolled patients, 107 were diagnosed based on combined genetic testing and filipin staining. Sixteen (11% out of 145 patients with available age-at-neurological-onset data had early-infantile neurological onset, 45 (31% had late-infantile onset; 45 (31% had juvenile onset and 39 (27% had adolescent/adult onset. The frequencies of neonatal jaundice, hepatomegaly and/or splenomegaly during infancy were greatest among early-infantile patients, and decreased with increasing age at neurological onset. The most frequent neurological manifestations were: ataxia (70%, vertical supranuclear gaze palsy (VSGP; 70%, dysarthria (66%, cognitive impairment (62%, dysphagia (52%. There were no notable differences in composite NP-C disability scores between age-at-neurological-onset groups. Miglustat therapy at enrolment was recorded in 117/163 (72% patients. Conclusions

  17. Angiotensin-I converting enzyme inhibitory and antioxidant activity of bioactive peptides produced by enzymatic hydrolysis of skin from grass carp (Ctenopharyngodon idella)

    DEFF Research Database (Denmark)

    Yi, Jierong; De Gobba, Cristian; Skibsted, Leif Horsfelt

    2017-01-01

    Grass carp skin pieces were homogenized in water and hydrolyzed by Alcalase®, collagenase, proteinase K, and/or trypsin at their optimum conditions. Samples were taken at various degrees of hydrolysis and were evaluated for antioxidant, antimicrobial, and angiotensin-converting enzyme inhibitory...... hydrolysates with trypsin slightly increased the antioxidant activity. Proteinase K, although only partially hydrolyzing the skin, also catalyzed the release of peptides with antioxidant and angiotensin-converting enzyme-inhibitory activities. These results show that skin by-products from grass carp can...... activities. Alcalase and collagenase completely hydrolyzed the skin with different rates, and released peptides with antioxidant and angiotensin-converting enzyme-inhibitory activity. These activities increased linearly with increasing degrees of hydrolysis. Subsequent incubation of the collagenase...

  18. Effect of Vaccinium myrtillus and its polyphenols on angiotensin-converting enzyme activity in human endothelial cells.

    Science.gov (United States)

    Persson, Ingrid A-L; Persson, Karin; Andersson, Rolf G G

    2009-06-10

    This study investigates if the connection between Vaccinium myrtillus and angiotensin-converting enzyme (ACE) might be an explanation of the pharmacological effects on circulation. Cultured endothelial cells from human umbilical veins were incubated with bilberry 25E extract. The main anthocyanidins combined in myrtillin chloride and separately in cyanidin, delphinidin, and malvidin, respectively, were examined concerning their effects on ACE. After 10 min of incubation with bilberry 25E, a significant, dose-dependent inhibition of ACE activity was seen, and after incubation with myrtillin chloride a significant inhibition was seen. No effect was seen with the anthocyanidins. The effect seems to be dependent on this specific mixture of anthocyanins in the bilberry. V. myrtillus may thus have the potential to prevent and protect against cardiovascular diseases.

  19. Wavelength Converters

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Wolfson, David

    1999-01-01

    . It is predicted that jitter accumulation can be minimised by using a 9-10 dB ratio between the signal and CW power also assuring a high extinction ratio. Using this guideline simulations show that 20 cross-gain modulation converters can be cascaded at 10 Gbit/s with only ~20 ps of accumulated jitter...... and an extinction ratio of ~10 dB.The regenerative capabilities of the cross-phase converters are described and verified experimentally at 20 Gbit/s, where the noise redistribution and improvement of the signal-to-noise ratio clearly is demonstrated by controlling the input power to an EDFA. In a similar experiment...... at 2.5 Gbit/s, the regeneration causes a reduction of the required input power to an in-line EDFA of ~6 dB for a power penalty of 1 dB at a bit error rate of 10-9. If two converters are concatenated the power requirement is reduced ~8 dB. Obviously, the power reduction allows for longer spans between...

  20. Converting poultry litter to activated carbon: optimal carbonization conditions and product sorption for benzene.

    Science.gov (United States)

    Guo, Mingxin; Song, Weiping

    2011-12-01

    To promote utilization of poultry litter as a source material for manufacturing low-cost activated carbon (AC) that can be used in wastewater treatment, this study investigated optimal production conditions and water-borne organic sorption potential of poultry litter-based AC. Pelletized broiler litter was carbonized at different temperatures for varied time periods and activated with steam at a range of flow rate and time. The AC products were examined for quality characteristics using standard methods and for organic sorption potentials using batch benzene sorption techniques. The study shows that the yield and quality of litter AC varied with production conditions. The optimal production conditions for poultry litter-based AC were carbonization at 700 degrees C for 45 min followed by activation with 2.5 ml min(-1) steam for another 45 min. The resulting AC possessed an iodine number of 454 mg g(-1) and a specific surface area of 403 m2 g(-1). It sorbed benzene in water following sigmoidal kinetic and isothermal patterns. The sorption capacity for benzene was 23.70 mg g(-1), lower than that of top-class commercial AC. The results, together with other reported research findings, suggest that poultry litter is a reasonable feedstock for low-cost AC applicable to pre-treat wastewater contaminated by organic pollutants and heavy metals.

  1. Aronia melanocarpa Elliot Reduces the Activity of Angiotensin I-Converting Enzyme—In Vitro and Ex Vivo Studies

    Directory of Open Access Journals (Sweden)

    Joanna Sikora

    2014-01-01

    Full Text Available Purpose. The aim of the study was to analyze the effects of two-month supplementation with chokeberry preparation on the activity of angiotensin I-converting enzyme (ACE in patients with metabolic syndrome (MS. During the in vitro stage of the study, we determined the concentration of chokeberry extract, which inhibited the activity of ACE by 50% (IC50. Methods. The participants (n=70 were divided into three groups: I—patients with MS who received chokeberry extract supplements, II—healthy controls, and III—patients with MS treated with ACE inhibitors. Results. After one and two months of the experiment, a decrease in ACE activity corresponded to 25% and 30%, respectively. We documented significant positive correlations between the ACE activity and the systolic (r=0.459, P=0.048 and diastolic blood pressure, (r=0.603, P=0.005 and CRP. The IC50 of chokeberry extract and captopril amounted to 155.4±12.1 μg/mL and 0.52±0.18 μg/mL, respectively. Conclusions. Our in vitro study revealed that chokeberry extract is a relatively weak ACE inhibitor. However, the results of clinical observations suggest that the favorable hypotensive action of chokeberry polyphenols may be an outcome of both ACE inhibition and other pleotropic effects, for example, antioxidative effect.

  2. Antioxidant capacity and angiotensin I converting enzyme inhibitory activity of a melon concentrate rich in superoxide dismutase.

    Science.gov (United States)

    Carillon, Julie; Del Rio, Daniele; Teissèdre, Pierre-Louis; Cristol, Jean-Paul; Lacan, Dominique; Rouanet, Jean-Max

    2012-12-01

    Antioxidant capacity and angiotensin 1-converting enzyme (ACE) inhibitory activity of a melon concentrate rich in superoxide dismutase (SOD-MC) were investigated in vitro. The total antioxidant capacity (TAC) was measured by the Trolox equivalent antioxidant capacity assay (TEAC), the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assay, and the ferric reducing antioxidant power assay (FRAP). The ability of the extract to scavenge three specific reactive oxygen species (superoxide radical anion (O(2)(-)), hydroxyl radical (HO()) and hydrogen peroxide (H(2)O(2))) was also investigated in order to better evaluate its antioxidant properties. Even if the measures of TAC were relatively low, results clearly established an antioxidant potential of SOD-MC that exhibited the highest radical-scavenging activity towards O(2)(-), with a IC(50) 12-fold lower than that of H(2)O(2) or HO(). This lets hypothesis that the antioxidant potential of SOD-MC could be mainly due to its high level of SOD. Moreover, for the first time, an ACE inhibitory activity of SOD-MC (IC(50)=2.4±0.1mg/mL) was demonstrated, showing that its use as a functional food ingredient with potential preventive benefits in the context of hypertension may have important public health implications and should be carefully considered. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Antioxidant and Angiotensin-Converting Enzyme Inhibitory Activity of Eucalyptus camaldulensis and Litsea glaucescens Infusions Fermented with Kombucha Consortium

    Directory of Open Access Journals (Sweden)

    Claudia I. Gamboa-Gómez

    2016-01-01

    Full Text Available Physicochemical properties, consumer acceptance, antioxidant and angiotensin-converting enzyme (ACE inhibitory activities of infusions and fermented beverages of Eucalyptus camaldulensis and Litsea glaucescens were compared. Among physicochemical parameters, only the pH of fermented beverages decreased compared with the unfermented infusions. No relevant changes were reported in consumer preference between infusions and fermented beverages. Phenolic profi le measured by UPLC MS/MS analysis demonstrated significant concentration changes of these compounds in plant infusions and fermented beverages. Fermentation induced a decrease in the concentration required to stabilize 50 % of DPPH radical (i.e. lower IC50. Additionally, it enhanced the antioxidant activity measured by the nitric oxide scavenging assay (14 % of E. camaldulensis and 49 % of L. glaucescens; whereas relevant improvements in the fermented beverage were not observed in the lipid oxidation assay compared with unfermented infusions. The same behaviour was observed in the inhibitory activity of ACE; however, both infusions and fermented beverages had lower IC50 than positive control (captopril. The present study demonstrated that fermentation has an influence on the concentration of phenolics and their potential bioactivity. E. camaldulensis and L. glaucescens can be considered as natural sources of biocompounds with antihypertensive potential used either as infusions or fermented beverages.

  4. Antioxidant and Angiotensin-Converting Enzyme Inhibitory Activity of Eucalyptus camaldulensis and Litsea glaucescens Infusions Fermented with Kombucha Consortium.

    Science.gov (United States)

    Gamboa-Gómez, Claudia I; González-Laredo, Rubén F; Gallegos-Infante, José Alberto; Pérez, Mş Del Mar Larrosa; Moreno-Jiménez, Martha R; Flores-Rueda, Ana G; Rocha-Guzmán, Nuria E

    2016-09-01

    Physicochemical properties, consumer acceptance, antioxidant and angiotensin-converting enzyme (ACE) inhibitory activities of infusions and fermented beverages of Eucalyptus camaldulensis and Litsea glaucescens were compared. Among physicochemical parameters, only the pH of fermented beverages decreased compared with the unfermented infusions. No relevant changes were reported in consumer preference between infusions and fermented beverages. Phenolic profile measured by UPLC MS/MS analysis demonstrated significant concentration changes of these compounds in plant infusions and fermented beverages. Fermentation induced a decrease in the concentration required to stabilize 50% of DPPH radical (i.e. lower IC50). Additionally, it enhanced the antioxidant activity measured by the nitric oxide scavenging assay (14% of E. camaldulensis and 49% of L. glaucescens); whereas relevant improvements in the fermented beverage were not observed in the lipid oxidation assay compared with unfermented infusions. The same behaviour was observed in the inhibitory activity of ACE; however, both infusions and fermented beverages had lower IC50 than positive control (captopril). The present study demonstrated that fermentation has an influence on the concentration of phenolics and their potential bioactivity. E. camaldulensis and L. glaucescens can be considered as natural sources of biocompounds with antihypertensive potential used either as infusions or fermented beverages.

  5. Fine-Mapping Angiotensin-Converting Enzyme Gene: Separate QTLs Identified for Hypertension and for ACE Activity

    Science.gov (United States)

    Chung, Chia-Min; Wang, Ruey-Yun; Fann, Cathy S. J.; Chen, Jaw-Wen; Jong, Yuh-Shiun; Jou, Yuh-Shan; Yang, Hsin-Chou; Kang, Chih-Sen; Chen, Chien-Chung; Chang, Huan-Cheng; Pan, Wen-Harn

    2013-01-01

    Angiotensin-converting enzyme (ACE) has been implicated in multiple biological system, particularly cardiovascular diseases. However, findings associating ACE insertion/deletion polymorphism with hypertension or other related traits are inconsistent. Therefore, in a two-stage approach, we aimed to fine-map ACE in order to narrow-down the function-specific locations. We genotyped 31 single nucleotide polymorphisms (SNPs) of ACE from 1168 individuals from 305 young-onset (age ≤40) hypertension pedigrees, and found four linkage disequilibrium (LD) blocks. A tag-SNP, rs1800764 on LD block 2, upstream of and near the ACE promoter, was significantly associated with young-onset hypertension (p = 0.04). Tag-SNPs on all LD blocks were significantly associated with ACE activity (p-value: 10–16 to ACE activity were found between exon13 and intron18 and between intron 20 and 3′UTR, as revealed by measured haplotype analysis. These two major QTLs of ACE activity and the moderate effect variant upstream of ACE promoter for young-onset hypertension were replicated by another independent association study with 842 subjects. PMID:23469169

  6. Pomegranate peel extract attenuates oxidative stress by decreasing coronary angiotensin-converting enzyme (ACE) activity in hypertensive female rats.

    Science.gov (United States)

    Dos Santos, Roger L; Dellacqua, Lais O; Delgado, Nathalie T B; Rouver, Wender N; Podratz, Priscila L; Lima, Leandro C F; Piccin, Mariela P C; Meyrelles, Silvana S; Mauad, Helder; Graceli, Jones B; Moyses, Margareth R

    2016-01-01

    Based on the antioxidant properties of pomegranate, this study was designed to investigate the effects of pomegranate peel extract on damage associated with hypertension and aging in a spontaneously hypertensive rat (SHR) model. The influence of pomegranate consumption was examined on systolic blood pressure (SBP), angiotensin-converting enzyme (ACE) coronary activity, oxidative stress, and vascular morphology. Four- or 28-wk-old SHR model rats were treated for 30 d, with terminal experimental animal age being 8 and 32 wk, respectively, with either pomegranate extract (SHR-PG) or filtered water (SHR). Data showed significant reduction in SBP and coronary ACE activity in both age groups. The levels of superoxide anion, a measure of oxidative stress, were significantly lower in animals in the SHR-PG group compared to SHR alone. Coronary morphology demonstrated total increases in vascular wall areas were in the SHR group, and pomegranate peel extract diminished this effect. Pomegranate peel extract consumption conferred protection against hypertension in the SHR model. This finding was demonstrated by marked reduction in coronary ACE activity, oxidative stress, and vascular remodelling. In addition, treatment was able to reduce SBP in both groups. Evidence indicates that the use of pomegranate peel extract may prove beneficial in alleviating coronary heart disease.

  7. Relationship of quadriceps muscle power and optimal shortening velocity with angiotensin-converting enzyme activity in older women

    Directory of Open Access Journals (Sweden)

    Kostka J

    2017-10-01

    Full Text Available Joanna Kostka,1,2 Joanna Sikora,3 Tomasz Kostka1 1Department of Geriatrics, Healthy Ageing Research Centre, 2Department of Physical Medicine, 3Laboratory of Bioanalysis, Department of Pharmaceutical Chemistry, Drug Analysis and Radiopharmacy, Medical University of Lodz, Lodz, Poland Background: The goal of this study was to assess whether angiotensin-converting enzyme (ACE activity is related to muscle function (strength, power and velocity, as well as to assess if ACE inhibitors (ACEIs and other angiotensin system blocking medications (ASBMs influence muscle performance in elderly women.Subjects and methods: Ninety-five community-dwelling elderly women took part in this study. Anthropometric data, blood ACE activity analysis, maximum power (Pmax and optimal shortening velocity (υopt of the knee extensor muscles, handgrip strength, physical activity (PA and functional performance were measured.Results: Women taking ACEI were on average almost 2 years older than the women who did not take ACEI. They took more medicines and were also characterized by significantly lower level of ACE, but they did not differ in terms of PA level, results of functional performance and parameters characterizing muscle functions. No correlations of ACE activity with Pmax and handgrip strength, as well as with PA or functional performance were found. Higher ACE activity was connected with lower υopt for women who did not take any ASBMs (rho =−0.37; p=0.01.Conclusion: Serum ACE activity was not associated with muscle strength, power and functional performance in both ASBM users and nonusers, but was associated with optimal shortening velocity of quadriceps muscles in older women. Further prospective studies are needed to assess if ACEIs or other ASBMs may slow down the decline in muscle function and performance. Keywords: sarcopenia, frailty, muscle strength, functional performance, aging, ACE inhibitors 

  8. Convertible barge

    Energy Technology Data Exchange (ETDEWEB)

    Howson, R.E.

    1988-08-23

    This patent describes a convertible barge, comprising: a. a deck; b. modules positioned on the deck in end to end relation and at least some of which contain pipeline processing equipment. The modules being removably attached to the deck, each module comprising a floor, ceiling, and a pair of side walls extending longitudinally of the barge between the ends; and c. means defining a closable opening comprising a roll-up door in at least one end of the modules for passing a pipeline portion from the module to a respectively adjacent module as the pipeline is being processed, for sealing the module during storage and for providing passageways between the modules and a view of pipe laying operations during use. A method for converting a barge to a lay barge, comprising: a. positioning on a deck of the barge in end to end relation of modules each of which has a floor, ceiling, and a pair of sidewalls extending longitudinally of the barge between the ends; b. providing pipeline process stations in at least some of the modules; c. removably attaching the modules to the deck; and d. providing a roll-up door in at least one of the modules ends of each module for passing a pipeline portion from the module to a respectively adjacent module as the pipeline is being processed and for providing passageways between the modules and a view of pipe laying operations during use.

  9. Association of angiotensin-converting enzyme activity and polymorphism with echocardiographic measures in familial and nonfamilial hypertrophic cardiomyopathy

    Directory of Open Access Journals (Sweden)

    P.C. Buck

    2009-08-01

    Full Text Available Angiotensin-converting enzyme (ACE activity and polymorphism contribute significantly to the prognosis of patients with cardiomyopathy. The aim of this study was to determine the activity and type of ACE polymorphism in patients with familial and nonfamilial hypertrophic cardiomyopathy (HCM and to correlate these with echocardiographic measurements (echo-Doppler. We studied 136 patients (76 males with HCM (69 familial and 67 nonfamilial cases. Mean age was 41 ± 17 years. DNA was extracted from blood samples for the polymerase chain reaction and the determination of plasma ACE levels. Left ventricular mass, interventricular septum, and wall thickness were measured. Mean left ventricular mass index, interventricular septum and wall thickness in familial and nonfamilial forms were 154 ± 63 and 174 ± 57 g/m² (P = 0.008, 19 ± 5 and 21 ± 5 mm (P = 0.02, and 10 ± 2 and 12 ± 3 mm (P = 0.0001, respectively. ACE genotype frequencies were DD = 35%, ID = 52%, and II = 13%. A positive association was observed between serum ACE activity and left ventricular mass index (P = 0.04. Logistic regression showed that ACE activity was twice as high in patients with familial HCM and left ventricular mass index ≥190 g/m² compared with the nonfamilial form (P = 0.02. No other correlation was observed between ACE polymorphisms and the degree of myocardial hypertrophy. In conclusion, ACE activity, but not ACE polymorphisms, was associated with the degree of myocardial hypertrophy in the patients with HCM.

  10. Medium Voltage Three-level Converters for the Grid Connection of aMulti-MW Wind Turbine

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2009-01-01

    Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid...

  11. Medium voltage three-level converters for the grid connection of a multi-MW wind turbine

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2009-01-01

    Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid...

  12. Hydrolysates of sheep cheese whey as a source of bioactive peptides with antioxidant and angiotensin-converting enzyme inhibitory activities.

    Science.gov (United States)

    Corrêa, Ana Paula Folmer; Daroit, Daniel Joner; Fontoura, Roberta; Meira, Stela Maris Meister; Segalin, Jeferson; Brandelli, Adriano

    2014-11-01

    Enzymatic proteolysis may be employed to release bioactive peptides, which have been investigated for potential benefits from both technological and human health perspectives. In this study, sheep cheese whey (SCW) was hydrolyzed with a protease preparation from Bacillus sp. P7, and the hydrolysates were evaluated for antioxidant and angiotensin I-converting enzyme (ACE)-inhibitory activities. Soluble protein and free amino acids increased during hydrolysis of SCW for up to 4h. Antioxidant activity of hydrolysates, evaluated by the 2,2'azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid radical scavenging method, increased 3.2-fold from 0 h (15.9%) to 6h of hydrolysis (51.3%). Maximum Fe(2+) chelation was reached in 3h hydrolysates, and the reducing power peaked at 1h of hydrolysis, representing 6.2 and 2.1-fold increase, respectively, when compared to that of non-hydrolyzed SCW. ACE inhibition by SCW (12%) was improved through hydrolysis, reaching maximal values (55% inhibition) in 4h, although 42% inhibition was already observed after 1h hydrolysis. The peptide LAFNPTQLEGQCHV, derived from β-lactoglobulin, was identified from 4-h hydrolysates. Such a biotechnological approach might be an interesting strategy for SCW processing, potentially contributing to the management and valorization of this abundant dairy byproduct. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Antioxidation, angiotensin converting enzyme inhibition activity, nattokinase, and antihypertension of Bacillus subtilis (natto)-fermented pigeon pea.

    Science.gov (United States)

    Lee, Bao-Hong; Lai, Yi-Syuan; Wu, She-Ching

    2015-12-01

    Because of the high incidence of cardiovascular diseases in Asian countries, traditional fermented foods from Asia have been increasingly investigated for antiatherosclerotic effects. This study investigated the production of nattokinase, a serine fibrinolytic enzyme, in pigeon pea by Bacillus subtilis fermentation. B. subtilis 14714, B. subtilis 14715, B. subtilis 14716, and B. subtilis 14718 were employed to produce nattokinase. The highest nattokinase activity in pigeon pea was obtained using B. subtilis 14715 fermentation for 32 hours. In addition, the levels of antioxidants (phenolics and flavonoids) and angiotensin converting enzyme inhibitory activity were increased in B. subtilis 14715-fermented pigeon pea, compared with those in nonfermented pigeon pea. In an animal model, we found that both water extracts of pigeon pea (100 mg/kg body weight) and water extracts of B. subtilis-fermented pigeon pea (100 mg/kg body weight) significantly improved systolic blood pressure (21 mmHg) and diastolic blood pressure (30 mmHg) in spontaneously hypertensive rats. These results suggest that Bacillus-fermented pigeon pea has benefits for cardiovascular health and can be developed as a new dietary supplement or functional food that prevents hypertension. Copyright © 2015. Published by Elsevier B.V.

  14. Antioxidation, angiotensin converting enzyme inhibition activity, nattokinase, and antihypertension of Bacillus subtilis (natto-fermented pigeon pea

    Directory of Open Access Journals (Sweden)

    Bao-Hong Lee

    2015-12-01

    Full Text Available Because of the high incidence of cardiovascular diseases in Asian countries, traditional fermented foods from Asia have been increasingly investigated for antiatherosclerotic effects. This study investigated the production of nattokinase, a serine fibrinolytic enzyme, in pigeon pea by Bacillus subtilis fermentation. B. subtilis 14714, B. subtilis 14715, B. subtilis 14716, and B. subtilis 14718 were employed to produce nattokinase. The highest nattokinase activity in pigeon pea was obtained using B. subtilis 14715 fermentation for 32 hours. In addition, the levels of antioxidants (phenolics and flavonoids and angiotensin converting enzyme inhibitory activity were increased in B. subtilis 14715-fermented pigeon pea, compared with those in nonfermented pigeon pea. In an animal model, we found that both water extracts of pigeon pea (100 mg/kg body weight and water extracts of B. subtilis-fermented pigeon pea (100 mg/kg body weight significantly improved systolic blood pressure (21 mmHg and diastolic blood pressure (30 mmHg in spontaneously hypertensive rats. These results suggest that Bacillus-fermented pigeon pea has benefits for cardiovascular health and can be developed as a new dietary supplement or functional food that prevents hypertension.

  15. New Quantitative Structure-Activity Relationship Model for Angiotensin-Converting Enzyme Inhibitory Dipeptides Based on Integrated Descriptors.

    Science.gov (United States)

    Deng, Baichuan; Ni, Xiaojun; Zhai, Zhenya; Tang, Tianyue; Tan, Chengquan; Yan, Yijing; Deng, Jinping; Yin, Yulong

    2017-11-08

    Angiotensin-converting enzyme (ACE) inhibitory peptides derived from food proteins have been widely reported for hypertension treatment. In this paper, a benchmark data set containing 141 unique ACE inhibitory dipeptides was constructed through database mining, and a quantitative structure-activity relationships (QSAR) study was carried out to predict half-inhibitory concentration (IC50) of ACE activity. Sixteen descriptors were tested and the model generated by G-scale descriptor showed the best predictive performance with the coefficient of determination (R2) and cross-validated R2 (Q2) of 0.6692 and 0.6220, respectively. For most other descriptors, R2 were ranging from 0.52 to 0.68 and Q2 were ranging from 0.48 to 0.61. A complex model combining all 16 descriptors was carried out and variable selection was performed in order to further improve the prediction performance. The quality of model using integrated descriptors (R2 0.7340 ± 0.0038, Q2 0.7151 ± 0.0019) was better than that of G-scale. An in-depth study of variable importance showed that the most correlated properties to ACE inhibitory activity were hydrophobicity, steric, and electronic properties and C-terminal amino acids contribute more than N-terminal amino acids. Five novel predicted ACE-inhibitory peptides were synthesized, and their IC50 values were validated through in vitro experiments. The results indicated that the constructed model could give a reliable prediction of ACE-inhibitory activity of peptides, and it may be useful in the design of novel ACE-inhibitory peptides.

  16. Optimization of SiC-based H5 and conergy-NPC transformerless PV inverters

    DEFF Research Database (Denmark)

    Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

    2015-01-01

    The transformerless dc/ac inverters are critical components in the rapidly growing market of grid-connected photovoltaic (PV) applications. They are synthesized by combining available solutions in terms of the power-section topology, power-semiconductors manufacturing technology, and structure...... and structure of the output filter (either LCL- or LLCL-type) in transformerless H5 and conergy-neutral point clamped (Conergy-NPC) PV inverters, which employ SiC-type power devices. The design results demonstrate that the optimized SiC-based H5 and Conergy-NPC transformerless PV inverters are more effective...... in terms of energy production than their nonoptimized and silicon (Si)-based counterparts. In addition, by reducing the market price of SiC-type power semiconductors to the level of Si-based power devices, enables the development of optimized SiC-based PV inverters with a lower cost of energy than...

  17. Genetic variation in the cholesterol transporter NPC1L1, ischaemic vascular disease, and gallstone disease

    DEFF Research Database (Denmark)

    Lauridsen, Bo Kobberø; Stender, Stefan; Frikke-Schmidt, Ruth

    2015-01-01

    variation in NPC1L1, mimicking the effect of ezetimibe, was associated with reduced risk of ischaemic vascular disease (IVD) and with increased risk of symptomatic gallstone disease. METHODS AND RESULTS: We included 67 385 individuals from the general population. Of these, 5255 and 3886 individuals...... developed IVD or symptomatic gallstone disease, respectively, during follow-up from 1977 to 2013. We genotyped four common NPC1L1 variants, previously associated with reduced LDL cholesterol levels, thus mimicking the effect of ezetimibe, and calculated a weighted genotype score. With increasing genotype...... score, LDL cholesterol decreased stepwise up to 3.5% (0.12 mmol/L) and total cholesterol up to 1.9% (0.11 mmol/L) (P-trend: 2 × 10(-12) and 2 × 10(-9)). The cumulative incidence by age of IVD decreased, while that of symptomatic gallstone disease increased as a function of increasing genotype score (P...

  18. Active peptides from skate (Okamejei kenojei) skin gelatin diminish angiotensin-I converting enzyme activity and intracellular free radical-mediated oxidation.

    Science.gov (United States)

    Ngo, Dai-Hung; Ryu, BoMi; Kim, Se-Kwon

    2014-01-15

    Skin gelatin of skate (Okamejei kenojei) was hydrolyzed using Alcalase, flavourzyme, Neutrase and protamex. It was found that the Alcalase hydrolysate exhibited the highest angiotensin-I converting enzyme (ACE) inhibitory activity. Then, Alcalase hydrolysate was further hydrolyzed with protease and separated by an ultrafiltration membrane system. Finally, two peptides responsible for ACE inhibitory activity were identified to be MVGSAPGVL (829Da) and LGPLGHQ (720Da), with IC50 values of 3.09 and 4.22μM, respectively. Moreover, the free radical-scavenging activity of the purified peptides was determined in human endothelial cells. In addition, the antioxidative mechanism of the purified peptides was evaluated by protein and gene expression levels of antioxidant enzymes. The current study demonstrated that the peptides derived from skate skin gelatin could be used in the food industry as functional ingredients with potent antihypertensive and antioxidant benefits. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. COMPARATIVE STUDY ON ANGIOTENSIN CONVERTING ENZYME INHIBITORY ACTIVITY OF HYDROLYSATE OF MEAT PROTEIN OF INDONESIAN LOCAL LIVESTOCKS

    Directory of Open Access Journals (Sweden)

    J. Jamhari

    2014-10-01

    Full Text Available The experiment was conducted to investigate the angiotensin converting enzyme (ACE inhibitoryactivity of hydrolysate in meat protein of Bali cattle, Kacang goat, native chicken, and local duck. Themeats of Bali cattle, Kacang goat, native chicken, and local duck were used in this study. The meatswere ground using food processor added with aquadest to obtain meat extract. The meat extracts werethen hydrolyzed using protease enzymes to obtain hydrolysate of meat protein. Protein concentration ofmeat extract and hydrolysate of meat protein were determined, and were confirmed by sodium dodecylsulfate - poly acrylamide gel electrophoresis (SDS-PAGE. ACE inhibitory activity of hydrolysate ofmeat protein derived from Bali cattle, Kacang goat, native chicken, and local duck was also determined.The results showed that protein concentration of hydrolysate of meat protein of Bali cattle, Kacang goat,native chicken, and local duck meat was significantly higher than their meat extracts. SDS-PAGEanalysis indicated that hydrolysate of meat protein of Bali cattle, Kacang goat, native chicken, and localduck had more peptides with lower molecular weight, compared to their meat extracts. Hydrolysate ofmeat protein of Bali cattle, Kacang goat, native chicken, and local duck had potencies in inhibiting ACEactivity, so it will potentially reduce blood pressure.

  20. Modulation Methods for Neutral-Point-Clamped Wind Power Converter Achieving Loss and Thermal Redistribution Under Low-Voltage Ride-Through

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2014-01-01

    The three-level neutral-point (NP)-clamped (3L-NPC) converter is a promising multilevel topology in the application of megawatt wind power generation systems. However, the growing requirements by grid codes may impose high stress and even give reliability problem to this converter topology....... This paper investigates the loss and thermal performances of a 10-MW 3L-NPC wind power inverter undergoing low-voltage ride-through (LVRT) operation. A series of new space vector modulation methods is then proposed to relocate the thermal loading among the power switching devices. It is concluded that...

  1. Differential effects of isoproterenol on the activity of angiotensin-converting enzyme in the rat heart and aorta

    Directory of Open Access Journals (Sweden)

    Busatto V.C.W.

    1999-01-01

    Full Text Available The excessive stimulation of beta-adrenergic receptors in the heart induces myocardial hypertrophy. There are several experimental data suggesting that this hypertrophy may also depend, at least partially, on the increase of local production of angiotensin II secondary to the activation of the cardiac renin-angiotensin system. In this study we investigated the effects of isoproterenol on the activity of angiotensin-converting enzyme (ACE in the heart and also in the aorta and plasma. Male Wistar rats weighing 250 to 305 g were treated with a dose of (±-isoproterenol (0.3 mg kg-1 day-1, N = 8 sufficient to produce cardiac hypertrophy without deleterious effects on the pumping capacity of the heart. Control rats (N = 7 were treated with vehicle (corn oil. The animals were killed one week later. ACE activity was determined in vitro in the four cardiac chambers, aorta and plasma by a fluorimetric assay. A significant hypertrophy was observed in both ventricular chambers. ACE activity in the atria remained constant after isoproterenol treatment. There was a significant increase (P<0.05 of ACE activity in the right ventricle (6.9 ± 0.9 to 8.2 ± 0.6 nmol His-Leu g-1 min-1 and in the left ventricle (6.4 ± 1.1 to 8.9 ± 0.8 nmol His-Leu g-1 min-1. In the aorta, however, ACE activity decreased (P<0.01 after isoproterenol (41 ± 3 to 27 ± 2 nmol His-Leu g-1 min-1 while it remained unchanged in the plasma. These data suggest that ACE expression in the heart can be increased by stimulation of beta-adrenoceptors. However, this effect is not observed on other local renin-angiotensin systems, such as the aorta. Our data also suggest that the increased sympathetic discharge and the elevated plasma concentration of catecholamines may contribute to the upregulation of ACE expression in the heart after myocardial infarction and heart failure.

  2. Convertible Stadium

    Science.gov (United States)

    1978-01-01

    Air flotation technology used in NASA's Apollo program has found an interesting application in Hawaii's Aloha Stadium near Honolulu. The stadium's configuration can be changed, by moving entire 7,000-seat sections on a cushion of air, for best accommodation of spectators and participants at different types of events. In most stadiums, only a few hundred seats can be moved, by rolling sections on wheels or rails. At Aloha Stadium, 28,000 of the 50,000 seats can be repositioned for better spectator viewing and, additionally, for improved playing conditions. For example, a stadium designed primarily for football may compromise the baseball diamond by providing only a shallow outfield. Aloha's convertibility allows a full-size baseball field as well as optimum configurations for many other types of sports and special events. The photos show examples. The stadium owes its versatility to air flotation technology developed by General Motors. Its first large-scale application was movement of huge segments of the mammoth Saturn V moonbooster during assembly operations at Marshall Space Flight Center.

  3. A continuous fluorescent assay for the determination of plasma and tissue angiotensin I-converting enzyme activity

    Directory of Open Access Journals (Sweden)

    Alves M.F.

    2005-01-01

    Full Text Available A continuous assay using internally quenched fluorescent peptides with the general sequence Abz-peptidyl-(DnpP-OH (Abz = ortho-aminobenzoic acid; Dnp = 2,4-dinitrophenyl was optimized for the measurement of angiotensin I-converting enzyme (ACE in human plasma and rat tissues. Abz-FRK(DnpP-OH, which was cleaved at the Arg-Lys bond by ACE, was used for the enzyme evaluation in human plasma. Enzymatic activity was monitored by continuous recording of the fluorescence (lambdaex = 320 nm and lambdaem = 420 nm at 37ºC, in 0.1 M Tris-HCl buffer, pH 7.0, with 50 mM NaCl and 10 µM ZnCl2. The assays can be performed directly in the cuvette of the fluorimeter and the hydrolysis followed for 5 to 10 min. ACE measurements in the plasma of 80 healthy patients with Hip-His-Leu and with Abz-FRK(DnpP-OH correlated closely (r = 0.90, P < 0.001. The specificity of the assay was demonstrated by the complete inhibition of hydrolysis by 0.5 µM lisinopril or captopril. Abz-FRK(DnpP-OH cleavage by ACE was monitored in rat lung, kidney, heart, and liver homogenates in the presence of a cocktail of inhibitors containing trans-epoxy-succinyl-L-leucylamido-(4-guanido-butene, pepstatin, phenyl-methylsulfonyl fluoride, N-tosyl-L-phenylalanyl-chloromethyl ketone, and N-tosyl-lysyl-chloromethyl ketone to prevent undesirable hydrolysis. ACE activity in lung, heart and kidney homogenates, but not in liver homogenates, was completely abolished by 0.5 µM lisinopril or captopril. The advantages of the method are the procedural simplicity and the high sensitivity providing a rapid assay for ACE determinations.

  4. Analysis and Comparison Based on Component Stress Factor of Dual Active Bridge and Isolated Full Bridge Boost Converters for Bidirectional Fuel Cells Systems

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Mira Albert, Maria del Carmen; Zhang, Zhe

    2014-01-01

    This paper presents an analysis and comparison of isolated topologies for bidirectional fuel cell systems. The analyzed topologies are the dua l active bridge (DAB) and the isolated full bridge boost converter (IFBBC). The analysis is performed based on the component stress factor (CSF). Results ...

  5. INFLUENCE OF CURCUMIN ON CYTOKINES CONTENT AND ANGIOTENSIN-CONVERTING ACTIVITY UNDER INTRAHIPPOCAMPUS ADMINISTRATION OF β-AMYLOID PEPTIDE IN RATS

    Directory of Open Access Journals (Sweden)

    Sokolik V. V.

    2015-08-01

    Full Text Available The purpose of this study was to investigate the effect of curcumin on cytokine response and angiotensin-converting activity in terms of intrahippocampus administration of ß-amyloid peptide in rats. Animals with experimental model of Alzheimer’s disease received nasal therapy aqueous solution of curcumin. Recorded concentration of cytokines (interleukin-1ß, interleukin-6, interleukin-10, tumor necrosis factor-α and angiotensin-converting activity in the parts of the brain (cerebral cortex and hippocampus and blood serum, as well as indicators of conditional reflex escapers action. Install a reduction in cytokine response intrahippocampus administering Aß42_Human and angiotensin-converting activity inhibition in the brain but not in the blood serum of animals under the action of curcumin. Recorded improvement in cognitive performance in rats with a model of Alzheimer’s disease as a result of curcumin therapy. Nasal treatment with an aqueous solution of curcumin has anti-inflammatory effect in the targeted parts of the brain (сerebral cortex and hippocampus, but inhibits angiotensin-converting activity.

  6. A Self-commissioning Notch Filter for Active Damping in a Three-Phase LCL -Filter-Based Grid-Tie Converter

    DEFF Research Database (Denmark)

    Pena-Alzola, Rafael; Liserre, Marco; Blaabjerg, Frede

    2014-01-01

    LCL-filters are a cost-effective solution to mitigate harmonic current content in grid-tie converters. In order to avoid stability problems, the resonance frequency of LCL-filters can be damped with active techniques that remove dissipative elements but increase control complexity. A notch filter...

  7. Genetic variation at the NPC1L1 gene locus, plasma lipoproteins, and heart disease risk in the elderly

    Science.gov (United States)

    Niemann-Pick C1-like 1 protein (NPC1L1) plays a critical role in intestinal cholesterol absorption. Our objective was to examine whether five variants (-133A>G, -18A>C, L272L, V1296V, and U3_28650A>G) at the NPC1L1 gene have effects on lipid levels, prevalence, and incidence of coronary heart diseas...

  8. The angiotensin converting enzyme (ACE) inhibitor, captopril disrupts the motility activation of sperm from the silkworm, Bombyx mori.

    Science.gov (United States)

    Nagaoka, Sumiharu; Kawasaki, Saori; Kawasaki, Hideki; Kamei, Kaeko

    2017-11-01

    Angiotensin I-converting enzyme (also known as peptidyl dicarboxypeptidase A, ACE, and EC 3.4.15.1), which is found in a wide range of organisms, cleaves C-terminal dipeptides from relatively short oligopeptides. Mammalian ACE plays an important role in the regulation of blood pressure. However, the precise physiological functions of insect ACE homologs have not been understood. As part of our effort to elucidate new physiological roles of insect ACE, we herein report a soluble ACE protein in male reproductive secretions from the silkmoth, Bombyx mori. Seminal vesicle sperm are quiescent in vitro, but vigorous motility is activated by treatment with either a glandula (g.) prostatica homogenate or trypsin in vitro. When seminal vesicle sperm were pre-incubated with captopril, a strong and specific inhibitor of mammalian ACE, and then stimulated to initiate motility by the addition of the g. prostatica homogenate or trypsin, the overall level of acquired motility was reduced in an inhibitor-concentration-dependent manner. In the course of this project, we detected ACE-related carboxypeptidase activity that was inhibited by captopril in both the vesicular (v.) seminalis of the noncopulative male reproductive tract and in the spermatophore that forms in the female bursa copulatrix at the time of mating, just as in an earlier report on the tomato moth, Lacanobia oleracea, which belongs to a different lepidopteran species (Ekbote et al., 2003a). Two distinct genes encoding ACE-like proteins were identified by analysis of B. mori cDNA, and were named BmAcer and BmAcer2, respectively [the former was previously reported by Quan et al. (2001) and the latter was first isolated in this paper]. RT-qPCR and Western blot analyses indicated that the BmAcer2 was predominantly produced in v. seminalis and transferred to the spermatophore during copulation, while the BmAcer was not detected in the adult male reproductive organs. A recombinant protein of BmAcer2 (devoid of a signal

  9. Association of plasminogen activator inhibitor-1 and angiotensin converting enzyme polymorphisms with recurrent pregnancy loss in Iranian women

    Directory of Open Access Journals (Sweden)

    Fatemeh Shakarami

    2015-10-01

    Full Text Available Background: Recurrent pregnancy loss (RPL defined by two or more failed pregnancies before 20 weeks of gestation. Several factors play a role in RPL including thrombophilic conditions which can be influenced by gene polymorphisms. Plasminogen activator inhibitor-1 (PAI-1 and angiotensin converting enzyme (ACE genes are closely related to fibrinolytic process, embryonic development and pregnancy success. Objective: The aim of this study was to investigate the relationship between RPL and common polymorphisms in ACE and PAI-1 genes. Materials and Methods: In this case control study, 100 women with recurrent abortions (at least two were selected as cases and 100 healthy women with two or more normal term deliveries without a history of abortion as controls. Total genomic DNA was isolated from blood leukocytes. The status of the PAI-1 4G/5G and ACE (D/I polymorphism was determined by PCR-RFLP. Results: Homozygosity for PAI-1 4G polymorphism was seen in 17 cases (17%, and 5 controls (5% (p=0.006 so patients with homozygote 4G mutation were significantly more prone to RPL in contrast to control group (OR: 4.63, % 95 CI: 1.55-13.84. In addition, 7 patients (7 %, and no one from the control group, were homozygote (I/I for ACE polymorphism (p=0.034, suggesting no significant associations between ACE D allele or DD genotype and RPL. Conclusion: Considering these results, because 4G/4G polymorphism for PAI-1 gene could be a thrombophilic variant leading to abortion, analysis of this mutation and other susceptibility factors are recommended in patients with RPL.

  10. The angiotensin-converting enzyme insertion/deletion polymorphism rs4340 associates with habitual physical activity among European American adults.

    Science.gov (United States)

    Bruneau, Michael; Angelopoulos, Theodore J; Gordon, Paul; Moyna, Niall; Visich, Paul; Zoeller, Robert; Seip, Rick; Bilbie, Stephen; Thompson, Paul; Devaney, Joseph; Gordish-Dressman, Heather; Hoffman, Eric; Pescatello, Linda S

    2017-09-01

    The angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism (rs4340) (ACE DIP) accounts for half of the variability in plasma ACE concentrations. ACE has been widely studied for its influence on sports performance; however, research on its influence in physical activity is limited and inconsistent. We examined the influence of the ACE DIP on physical activity among 461 European Americans. Subjects completed the Paffenbarger Physical Activity Questionnaire for weekly walking distance. Multivariate analysis of covariance (MANCOVA) tested log-transformed differences in weekly walking distance among ACE DIP genotypes (II, ID, DD) with gender as a fixed factor, and age and body mass index (BMI) as covariates. Because we found a significant ACE DIPxBMI interaction (P = 0.03), we categorized the sample by normal weight (NW: BMIMANCOVA with multiple comparison adjustments. NW adults with ACE II walked 15.8 ± 11.1 km/week, ID 13.2 ± 10.6 km/week, and DD 17.9 ± 13.0 km/week, with ID walking less than II (P = 0.03) and DD (P = 0.01). OW adults with ACE II walked 16.7 ± 12.6 km/week, ID 13.8 ± 11.6 km/week, and DD 9.7 ± 9.0 km/week, with DD walking less than II (P = 0.02). Weekly walking distance was 8.2 ± 2.4 km/week less among OW adults with ACE DD than NW (P = 0.02). BMI interacted with ACE DD such that OW walked ~8.2 km/week less than NW, potentially equating to a body weight differential of ~3.5 kg annually.

  11. Angiotensin I-converting enzyme inhibitory activity and antioxidant capacity of bioactive peptides derived from enzymatic hydrolysis of buffalo milk proteins

    DEFF Research Database (Denmark)

    Abdel-Hamid, Mahmoud; Otte, Jeanette; De Gobba, Cristian

    2017-01-01

    Buffaloes' milk, which is consumed in many parts of the world, is a little-explored source of bioactive peptides. The angiotensin converting enzyme (ACE)-inhibitory activity and the antioxidant capacity of peptides from buffaloes' milk were examined. A retentate from buffaloes' skimmed milk......-inhibitory (FPGPIPK, IPPK, IVPN, and QPPQ) and antioxidant (YPSG, HPFA and KFQ) activities. The results obtained showed the potential of buffaloes' milk proteins to release ACE-inhibitory and antioxidant peptides...

  12. NPC-EXs Alleviate Endothelial Oxidative Stress and Dysfunction through the miR-210 Downstream Nox2 and VEGFR2 Pathways

    Directory of Open Access Journals (Sweden)

    Hua Liu

    2017-01-01

    Full Text Available We have demonstrated that neural progenitor cells (NPCs protect endothelial cells (ECs from oxidative stress. Since exosomes (EXs can convey the benefit of parent cells through their carried microRNAs (miRs and miR-210 is ubiquitously expressed with versatile functions, we investigated the role of miR-210 in the effects of NPC-EXs on oxidative stress and dysfunction in ECs. NPCs were transfected with control and miR-210 scramble/inhibitor/mimic to generate NPC-EXscon, NPC-EXssc, NPC-EXsanti-miR-210, and NPC-EXsmiR-210. The effects of various NPC-EXs on angiotensin II- (Ang II- induced reactive oxygen species (ROS overproduction, apoptosis, and dysfunction, as well as dysregulation of Nox2, ephrin A3, VEGF, and p-VEGFR2/VEGFR2 in ECs were evaluated. Results showed (1 Ang II-induced ROS overproduction, increase in apoptosis, and decrease in tube formation ability, accompanied with Nox2 upregulation and reduction of p-VEGFR2/VEGFR2 in ECs. (2 Compared to NPC-EXscon or NPC-EXssc, NPC-EXsanti-miR-210 were less whereas NPC-EXsmiR-210 were more effective on attenuating these detrimental effects induced by Ang II in ECs. (3 These effects of NPC-EXsanti-miR-210 and NPC-EXsmiR-210 were associated with the changes of miR-210, ephrin A3, VEGF, and p-VEGFR2/VEGFR2 ratio in ECs. Altogether, the protective effects of NPC-EXs on Ang II-induced endothelial injury through miR-210 which controls Nox2/ROS and VEGF/VEGFR2 signals were studied.

  13. The high efficiency transformer-less PV inverter topologies derived from NPC topology

    DEFF Research Database (Denmark)

    Ma, Lin; Kerekes, Tamas; Teodorescu, Remus

    2009-01-01

    The grid-connected photovoltaic (PV) systems are an important part of renewable energy sources and their integration is getting more and more widespread. In order to improve the efficiency, practicality and reliability of the PV systems, many kinds of new inverter topologies have been proposed...... to avoid using a grid isolation transformer. The NPC topology and two other derived topologies are presented and analyzed in this paper. Validated by experiments, it has been proven that they are very suitable for using in transformer-less PV applications due to high efficiency, low leakage current and EMI...

  14. Bisphenol A promotes cholesterol absorption in Caco-2 cells by up-regulation of NPC1L1 expression.

    Science.gov (United States)

    Feng, Dan; Zou, Jun; Zhang, Shanshan; Li, Xuechun; Li, Peiyang; Lu, Minqi

    2017-01-06

    Bisphenol A (BPA), an commonly exposed environmental chemicals in humans, has been shown to have a hypercholesterolemic effect with molecular mechanism not clear. Since intestinal cholesterol absorption plays a major role in maintaining total body cholesterol homeostasis, the present study is to investigate whether BPA affects cholesterol absorption in the intestinal Caco-2 cells. The Caco-2 cells were pretreated with BPA at different concentrations for 24 h and then incubated with radioactive micellar cholesterol for 2 h. The absorption of radioactive cholesterol was quantified by liquid scintillation. The expression of Niemann-Pick C1-like 1 (NPC1L1) and sterol regulatory element binding protein-2 (SREBP-2) was analyzed by Western blot and qPCR. We found that confluent Caco-2 cells expressed NPC1L1, and the absorption of cholesterol in the cells was inhibited by ezetimibe, a specific inhibitor of NPC1L1. We then pretreated the cells with 0.1-10 nM BPA for 24 h and found that BPA at 1 and 10 nM doses promoted cholesterol absorption. In addition, we found that the BPA-induced promotion of cholesterol absorption was associated with significant increase in the levels of NPC1L1 protein and NPC1L1 mRNA. Moreover, the stimulatory effects of BPA on cholesterol absorption and NPC1L1 expression could be prevented by blockade of the SREBP-2 pathway. This study provides the first evidence that BPA promotes cholesterol absorption in the intestinal cells and the stimulatory effect of BPA is mediated, at least in part, by SREBP-2-NPC1L1 signaling pathway.

  15. Novel activity of human angiotensin I converting enzyme: release of the NH2- and COOH-terminal tripeptides from the luteinizing hormone-releasing hormone.

    OpenAIRE

    Skidgel, R A; Erdös, E G

    1985-01-01

    Angiotensin I converting enzyme (ACE; kininase II; peptidyldipeptide hydrolase, EC 3.4.15.1) cleaves COOH-terminal dipeptides from active peptides containing a free COOH terminus. We investigated the hydrolysis of luteinizing hormone-releasing hormone (LH-RH) by homogeneous human ACE. Although this decapeptide is blocked at both the NH2 and COOH termini, it was metabolized to several peptides, which were separated by HPLC and identified by amino acid analysis. A major product was the NH2-term...

  16. A Nup133-dependent NPC-anchored network tethers centrosomes to the nuclear envelope in prophase.

    Science.gov (United States)

    Bolhy, Stéphanie; Bouhlel, Imène; Dultz, Elisa; Nayak, Tania; Zuccolo, Michela; Gatti, Xavier; Vallee, Richard; Ellenberg, Jan; Doye, Valérie

    2011-03-07

    Centrosomes are closely associated with the nuclear envelope (NE) throughout the cell cycle and this association is maintained in prophase when they separate to establish the future mitotic spindle. At this stage, the kinetochore constituents CENP-F, NudE, NudEL, dynein, and dynactin accumulate at the NE. We demonstrate here that the N-terminal domain of the nuclear pore complex (NPC) protein Nup133, although largely dispensable for NPC assembly, is required for efficient anchoring of the dynein/dynactin complex to the NE in prophase. Nup133 exerts this function through an interaction network via CENP-F and NudE/EL. We show that this molecular chain is critical for maintaining centrosome association with the NE at mitotic entry and contributes to this process without interfering with the previously described RanBP2-BICD2-dependent pathway of centrosome anchoring. Finally, our study reveals that tethering of centrosomes to the nuclear surface at the G2/M transition contributes, along with other cellular mechanisms, to early stages of bipolar spindle assembly.

  17. KARAKTERISTIK FISIK, KIMIA, MIKROBIOLOGI WHEY KEFIR DAN AKTIVITASNYA TERHADAP PENGHAMBATAN ANGIOTENSIN CONVERTING ENZYME (ACE [Physical, Chemical and Microbiological Characteristics of Whey Kefir and Its Angiotensin Converting Enzyme (ACE Inhibitory Activity

    Directory of Open Access Journals (Sweden)

    Andi Febrisiantosa*

    2013-12-01

    Full Text Available This study was conducted to evaluate the characteristics of whey-based kefir products and their activity to inhibit the angiotensin converting enzyme (ACE. Kefir was produced by using many types of whey, namely SK: skim milk based kefir (control; WK: gouda cheese whey based kefir; and WKB: commercial whey powder based kefir. The experimental design was a completely randomized design. Each treatment was conducted in triplicates. Kefirs were evaluated for physical and chemical properties (pH, total titratable acidity, viscosity, protein, fat, lactose, and alcohol, microbiological (lactic acid bacteria and yeast population, peptide concentration, ACE inhibition, IC50 and Inhibition Efficiency Ratio (IER. The results showed that the types of whey used for kefir productions significantly affected the physical and chemical characteristics of the products (p0.05. The peptide concentration and ACE inhibitory activity of WK, 1.54±0.02 mg/mL and 73.07±0.91%, was significantly higher (p0.05 from the control (47.19±0.09% per mg/mL but was significantly higher (p<0.05 than that of WKB (45.75±0.18% per mg/mL. This research indicated that whey kefir is a potential source of bioactive peptide for antihypertention agent.

  18. Parallel input parallel output high voltage bi-directional converters for driving dielectric electro active polymer actuators

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2014-01-01

    Dielectric electroactive polymer (DEAP) actuators are capacitive devices which provide mechanical motions when charged electrically. The charging characteristics of a DEAP actuator depends on its size, voltage applied to its electrodes, and its operating frequency. The main idea of this paper....... This enables operating the DEAP actuators in various static and dynamic applications e.g. positioning, vibration generation or damping, and pumps. The proposed idea is experimentally verified by connecting three high voltage converters in parallel to operate a single DEAP actuator. The experimental results...... with both film capacitive load and the DEAP actuator are shown for a maximum charging voltage of 2 kV....

  19. Modular Multilevel Converters Based Variable Speed Wind Turbines for Grid Faults

    DEFF Research Database (Denmark)

    Deng, Fujin; Liu, Dong; Wang, Yanbo

    2016-01-01

    The modular multilevel converter (MMC) becomes attractive in the medium- and high-power application with high modularity. In this paper, the MMC is proposed to be applied in the variable speed wind turbine (VSWT) based on the full-scale back-to-back (BTB) power converter, where the generator......-side converter is the three-level neutral-point-clamped (NPC) converter and the grid-side converter is the three-phase MMC. A control strategy is also presented for the MMC based VSWT for the second-order harmonic current elimination. The proposed MMC based VSWT and control not only mitigate the voltage ripple...... of the proposed MMC based VSWT and control are conducted with a detailed PSCAD/EMTDC model, and the results show their effectiveness....

  20. Impact of modulation strategies on power devices loading for 10 MW multilevel wind power converter

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Isidori, Andrea; Rossi, Fabio Mario

    2012-01-01

    the dynamics of the system using different kinds of modulation strategies, identifying which methods can improve the converter efficiency. It is concluded that 60° discontinuous PWM modulation strategies show less power losses in the semiconductor devices and will increase the overall efficiency......This paper focuses on the control and modulation of a three-level Neutral Point Clamped (3L-NPC) back-to-back full scale converter for a 10 MW direct-drive wind turbine, equipped with a Permanent Magnet Synchronous Generator (PMSG). Emphasis is oriented towards the investigation of the power losses...

  1. Optimization of SiC-based H5 and Conergy-NPC transformerless PV inverters

    DEFF Research Database (Denmark)

    Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

    2013-01-01

    The transformerless DC/AC inverters are critical components in the rapidly growing market of grid-connected Photovoltaic (PV) applications. Also, the SiC-based power semiconductors are capable to operate reliably at high operating temperature and switches frequency levels. In this paper, a new...... design technique is presented for optimizing the switching frequency and structure of the LCL-type output filter in transformerless H5 and Conergy-NPC PV inverters, which employ SiC-type power devices. The design optimization results demonstrate that the optimized SiC-based PV inverters are more...... effective in terms of energy production than their non-optimized and Si-based counterparts. Reducing the market price of SiC-type power semiconductors enables to design optimized PV inverters with a lower cost of energy than that of PV inverters employing Si technology, thus maximizing the economic...

  2. High performance fuzzy sliding mode control of DFIG supplied by seven level NPC inverter

    Directory of Open Access Journals (Sweden)

    Mohamed BENKAHLA

    2017-09-01

    Full Text Available This article presents the powers control of a variable speed wind turbine (WT based on a doubly fed induction generator (DFIG because of their advantages in terms of economy and control. The considered system consists of a double fed induction generator whose stator is connected directly to the network and its rotor is supplied by seven-level inverter with structure NPC are well used to minimize the harmonics absorbed by the DFIG. In order to control the power flowing between the stator of the DFIG and the grid. Have been studied and compared two types of controllers : Sliding Mode Control (SMC and Fuzzy SMC (FSMC. Their respective performances are compared in terms of power reference tracking, response to sudden speed variations, sensitivity to perturbations and robustness against machine parameters variations.

  3. A novel approach to analyze lysosomal dysfunctions through subcellular proteomics and lipidomics: the case of NPC1 deficiency

    Science.gov (United States)

    Tharkeshwar, Arun Kumar; Trekker, Jesse; Vermeire, Wendy; Pauwels, Jarne; Sannerud, Ragna; Priestman, David A.; Te Vruchte, Danielle; Vints, Katlijn; Baatsen, Pieter; Decuypere, Jean-Paul; Lu, Huiqi; Martin, Shaun; Vangheluwe, Peter; Swinnen, Johannes V.; Lagae, Liesbet; Impens, Francis; Platt, Frances M.; Gevaert, Kris; Annaert, Wim

    2017-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) have mainly been used as cellular carriers for genes and therapeutic products, while their use in subcellular organelle isolation remains underexploited. We engineered SPIONs targeting distinct subcellular compartments. Dimercaptosuccinic acid-coated SPIONs are internalized and accumulate in late endosomes/lysosomes, while aminolipid-SPIONs reside at the plasma membrane. These features allowed us to establish standardized magnetic isolation procedures for these membrane compartments with a yield and purity permitting proteomic and lipidomic profiling. We validated our approach by comparing the biomolecular compositions of lysosomes and plasma membranes isolated from wild-type and Niemann-Pick disease type C1 (NPC1) deficient cells. While the accumulation of cholesterol and glycosphingolipids is seen as a primary hallmark of NPC1 deficiency, our lipidomics analysis revealed the buildup of several species of glycerophospholipids and other storage lipids in selectively late endosomes/lysosomes of NPC1-KO cells. While the plasma membrane proteome remained largely invariable, we observed pronounced alterations in several proteins linked to autophagy and lysosomal catabolism reflecting vesicular transport obstruction and defective lysosomal turnover resulting from NPC1 deficiency. Thus the use of SPIONs provides a major advancement in fingerprinting subcellular compartments, with an increased potential to identify disease-related alterations in their biomolecular compositions.

  4. Active and Reactive Power Control Strategy for Grid-Connected Six-Phase Generator by Using Multi-Modular Matrix Converters

    Directory of Open Access Journals (Sweden)

    David Caballero

    2016-12-01

    Full Text Available This paper proposes an active and reactive power control strategy based on predictive control approaches applied to gridconnected renewable energy systems. To accomplish this a multi-modular matrix converter topologies are used in combination with a simple but efficient grid synchronization strategy. The theoretical performance analysis is performed considering a six-phase wind energy generator system interconnected with the grid. Results based on a MATLAB/Simulink simulation environment are discussed and the most relevant characteristics of the proposed control technique are highlighted considering the total harmonic distortion and the mean squared error as a parameters of performance.

  5. Junction temperature measurements via thermo-sensitive electrical parameters and their application to condition monitoring and active thermal control of power converters

    DEFF Research Database (Denmark)

    Baker, Nick; Liserre, Marco; Dupont, L.

    2013-01-01

    implementation of active thermal control to reduce losses and increase lifetime can be performed given an accurate knowledge of temperature. Temperature measurements via thermo-sensitive electrical parameters (TSEP) are one way to carry out immediate temperature readings on fully packaged devices. However......, successful implementation of these techniques during the actual operation of a device has not yet been achieved. This paper provides an overview of literature where the usage of TSEPs has been hypothesised or realised in realistic power electronic converter setups. Barriers and limitations preventing wider...

  6. A single leg switched PWM method for three-phase H-Bridge Voltage Source Converters

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2009-01-01

    This paper proposes a single leg switched or a hybrid PWM (HPWM) method for three-phase three-level H-Bridge Voltage Source Converters (3L-HB-VSCs). By means of the proposed modulation, a 3L-HB-VSC can generate the same output as a three-level neutral point clamped (3L-NPC) VSC with phase...... disposition (PD) PWM provided that the outputs of 3L-HBVSC are isolated by transformers or connected to open winding machines. Thus, the proposed method is called PD-HPWM. Moreover, it is emphasized that 3L-HB-VSC with HPWM utilizes its switches similar to 3L-NPC-VSC. Compared to 3L-NPC-VSCs, 3L......-HB-VSCs (without neutral point clamping diodes) have simpler, more modular, and more reliable 2L circuit structure. Therefore, this method encourages the use of 3L-HB-VSCs in the applications utilizing transformers such as grid-side converters of multi-MW wind turbines. The proposed PWM method's performance...

  7. Effect of Combination of Angiotensin-Converting Enzyme Inhibitors and Vitamin D Receptor Activators on Cardiac Oxidative Stress in Diabetic Rats.

    Science.gov (United States)

    Ali, Tarek Mohamed; Mehanna, Osama Mahmoud; Elsaid, Amgad Gaber; Askary, Ahmad El

    2016-08-01

    The principle mediator of diabetic myocardial injury is oxidative stress. The aim was to compare the effect of monotherapy with enalapril, angiotensin-converting enzyme inhibitor and paricalcitol (vitamin D receptor activator), to the combined therapy with both drugs on the cardiac oxidant-antioxidant balance in the type 2 diabetic rats. A total of 50 male Sprague-Dawley rats were divided into 5 groups, namely the normal control and diabetic, vehicle, enalapril, paricalcitol and paricalcitol and enalapril-treated groups. Enalapril was given at a dose of (25mg/L) in drinking water once daily and paricalcitol was given intraperitoneally (0.8μg/kg/3 × week) for 3 months. Glycemic status, cardiac oxidant-antioxidant parameters and histologic examination were determined. Paricalcitol and combined treatment significantly (P model assessment-insulin resistance, cardiac malondialdehyde and nitric oxide. Moreover, they significantly (P < 0.01) increased the levels of insulin and c-peptide compared to diabetic control rats. Combined treatment significantly (P < 0.01) raised the level of glutathione, glutathione S-transferase and catalase more than monotherapy. The combination of angiotensin-converting enzyme inhibitors and vitamin D receptor activators has a superior effect on reducing cardiac oxidative stress by raising antioxidant activity than monotherapy in diabetic rats. Copyright © 2016 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.

  8. Gender difference of serum angiotensin-converting enzyme (ACE) activity in DD genotype of ACE insertion/deletion polymorphism in elderly Chinese.

    Science.gov (United States)

    Zhang, Ya-Feng; Cheng, Qiong; Tang, Nelson L S; Chu, Tanya T W; Tomlinson, Brian; Liu, Fan; Kwok, Timothy C Y

    2014-12-01

    In this study we investigated the gender difference of serum angiotensin-converting enzyme (ACE) activity in a population of Hong Kong-dwelling elderly Chinese. A total of 1767 (843 male, 924 female) Hong Kong-dwelling elderly Chinese were recruited. ACE I/D genotypes were identified by polymerase chain reaction amplification and serum ACE activity was determined using a commercially available kinetic kit. ACE I/D genotype distribution was compared by chi-square test, the correlation between ACE I/D polymorphism and serum ACE activity was analysed by ANOVA test and gender difference of serum ACE activity of different genotypes was compared by independent sample t-test. No statistically significant difference of genotype distribution between male and female subjects was found. Serum ACE activity was significantly correlated with ACE genotype. Overall, there was no gender difference of serum ACE activity; however, when sub-grouping the subjects by ACE I/D genotype, male subjects with DD genotype had higher serum ACE activity than female subjects with DD genotype. No significant gender difference of genotype distribution was found in elderly Chinese. Serum ACE activity was significantly correlated with ACE I/D polymorphism in elderly Chinese. Male subjects with DD genotype had higher serum ACE activity than female subjects with DD genotype. © The Author(s) 2013.

  9. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers.......Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers....

  10. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on air-optical wavelength converter types based on semiconductor optical amplifiers.......Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on air-optical wavelength converter types based on semiconductor optical amplifiers....

  11. Technologies for converter topologies

    Science.gov (United States)

    Zhou, Yan; Zhang, Haiyu

    2017-02-28

    In some embodiments of the disclosed inverter topologies, an inverter may include a full bridge LLC resonant converter, a first boost converter, and a second boost converter. In such embodiments, the first and second boost converters operate in an interleaved manner. In other disclosed embodiments, the inverter may include a half-bridge inverter circuit, a resonant circuit, a capacitor divider circuit, and a transformer.

  12. Power Converters for Accelerators

    CERN Document Server

    Visintini, R.

    2015-06-15

    Particle accelerators use a great variety of power converters for energizing their sub-systems; while the total number of power converters usually depends on the size of the accelerator or combination of accelerators (including the experimental setup), the characteristics of power converters depend on their loads and on the particle physics requirements: this paper aims to provide an overview of the magnet power converters in use in several facilities worldwide.

  13. Operating and Loading Conditions of a Three-Level Neutral-Point-Clamped Wind Power Converter Under Various Grid Faults

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2014-01-01

    , the thermal loading of the wind power converter under various grid faults is still not yet clarified, particularly at megawatt power level. In this paper, the impacts by three types of grid faults to a three-level neutral-point-clamped (3L-NPC) wind power converter in terms of operating and loading conditions......In order to fulfill the growing demands from the grid side, full-scale power converters are becoming popular in the wind turbine system. The low-voltage ride-through (LVRT) requirements may not only cause control problems but also result in overstressed components for the power converter. However...... are analytically solved and simulated. It has been found that the operating and loading conditions of the converter under LVRT strongly depend on the types/severity values of grid voltage dips and also the chosen control algorithms. The thermal distribution among the three phases of the converter may be quite...

  14. Simvastatin promotes NPC1-mediated free cholesterol efflux from lysosomes through CYP7A1/LXRα signalling pathway in oxLDL-loaded macrophages.

    Science.gov (United States)

    Xu, Xiaoyang; Zhang, Aolin; Halquist, Matthew S; Yuan, Xinxu; Henderson, Scott C; Dewey, William L; Li, Pin-Lan; Li, Ningjun; Zhang, Fan

    2017-02-01

    Statins, 3-hydroxyl-3-methylglutaryl coenzyme A reductase inhibitors, are the first-line medications prescribed for the prevention and treatment of coronary artery diseases. The efficacy of statins has been attributed not only to their systemic cholesterol-lowering actions but also to their pleiotropic effects that are unrelated to cholesterol reduction. These pleiotropic effects have been increasingly recognized as essential in statins therapy. This study was designed to investigate the pleiotropic actions of simvastatin, one of the most commonly prescribed statins, on macrophage cholesterol homeostasis with a focus on lysosomal free cholesterol egression. With simultaneous nile red and filipin staining, analysis of confocal/multi-photon imaging demonstrated that simvastatin markedly attenuated unesterified (free) cholesterol buildup in macrophages loaded with oxidized low-density lipoprotein but had little effect in reducing the sizes of cholesteryl ester-containing lipid droplets; the reduction in free cholesterol was mainly attributed to decreases in lysosome-compartmentalized cholesterol. Functionally, the egression of free cholesterol from lysosomes attenuated pro-inflammatory cytokine secretion. It was determined that the reduction of lysosomal free cholesterol buildup by simvastatin was due to the up-regulation of Niemann-Pick C1 (NPC1), a lysosomal residing cholesterol transporter. Moreover, the enhanced enzymatic production of 7-hydroxycholesterol by cytochrome P450 7A1 and the subsequent activation of liver X receptor α underscored the up-regulation of NPC1. These findings reveal a novel pleiotropic effect of simvastatin in affecting lysosomal cholesterol efflux in macrophages and the associated significance in the treatment of atherosclerosis. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  15. The relationship between angiotensin-converting enzyme (ACE) insertion (I) / deletion (D) polymorphism, serum ACE activity and bone mineral density (BMD) in older Chinese.

    Science.gov (United States)

    Zhang, Ya-Feng; Wang, Hong; Cheng, Qiong; Qin, Ling; Tang, Nelson Ls; Leung, Ping-Chong; Kwok, Timothy Cy

    2017-01-01

    In this study, we set out to investigate the relationship between angiotensin-converting enzyme ( ACE) I/D polymorphism, serum ACE activity and bone mineral density (BMD) in older Chinese. A standardized, structured, face-to-face interview was performed to collect demographic information. BMD was measured using dual-energy X-ray absorptiometry (DXA). I/D genotypes of ACE were determined by polymerase chain reaction (PCR) amplification. Serum ACE activity was determined photometrically by a commercially available kinetic kit. Multiple linear regression analysis was used to examine the relationship between ACE I/D polymorphism, serum ACE activity and BMD. A total of 1567 males and 1760 females were selected for analyzing the relationship between ACE I/D polymorphism and BMD. There was no significant difference in spine BMD, total hip BMD and femur neck BMD among different ACE I/D genotypes both in males and females. A total of 1699 males and 1739 females were selected for analyzing the relationship between serum ACE activity and BMD. There was also no significant difference in spine BMD, total hip BMD and femur neck BMD among different serum ACE activity groups both in males and females. There was no relationship between ACE I/D polymorphism, serum ACE activity and BMD in older Chinese.

  16. Discontinuous PWM Modulation Strategy with Circuit-Level Decoupling Concept of Three-Level Neutral-Point Clamped (NPC) Inverter

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2013-01-01

    A new pulse width modulation (PWM) strategy which is an alternative approach of discontinuous PWM (DPWM) for a three-level neutral point clamped (NPC) inverter is developed and presented in this paper. The proposed PWM scheme not only takes advantage of the special properties available in NPC...... can be simplified. The salient features of the proposed scheme, as compared with the existing carrier-based DPWM strategies, are: 1) its reduced computational processing time, 2) its capability to balance the DC-link voltage without any additional control and 3) its reduced complexity e.g. only one...... carrier wave needed for pulse width modulating. Same as a space vector modulation, the maximum modulation index, 1.1547, can be attainable by the proposed scheme. Moreover, compared to conventional continuous sinusoidal pulse width modulation, using this technique here the switching losses of the devices...

  17. New strategy for eliminating zero-sequence circulating current between parallel operating three-level NPC voltage source inverters

    DEFF Research Database (Denmark)

    Li, Kai; Dong, Zhenhua; Wang, Xiaodong

    2018-01-01

    A novel strategy based on a zero common mode voltage pulse-width modulation (ZCMV-PWM) technique and zero-sequence circulating current (ZSCC) feedback control is proposed in this study to eliminate ZSCCs between three-level neutral point clamped (NPC) voltage source inverters, with common AC and DC...... buses, that are operating in parallel. First, an equivalent model of ZSCC in a three-phase three-level NPC inverter paralleled system is developed. Second, on the basis of the analysis of the excitation source of ZSCCs, i.e., the difference in common mode voltages (CMVs) between paralleled inverters......, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can...

  18. A high voltage DC-DC converter driving a Dielectric Electro Active Polymer actuator for wind turbine flaps

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2012-01-01

    The Dielectric Electro Active Polymer (DEAP) material is a very thin (~80 μm) silicone elastomer film with a compliant metallic electrode layer on both sides. The DEAP is fundamentally a capacitor that is capable of very high strain. The property that the polymer changes its shape, as a result...

  19. Dielectric Electro Active Polymer Incremental Actuator Driven by Multiple High-Voltage Bi-directional DC-DC Converters

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    This paper presents driving circuit for a recently invented dielectric electro active polymer (DEAP) incremental actuator. The basic operation of such an actuator is bioinspired from the movement of an inchworm. The actuator consists of three electrically isolated, and mechanically connected capa...

  20. High-pressure improves enzymatic proteolysis and the release of peptides with angiotensin I converting enzyme inhibitory and antioxidant activities from lentil proteins.

    Science.gov (United States)

    Garcia-Mora, P; Peñas, E; Frias, J; Gomez, R; Martinez-Villaluenga, C

    2015-03-15

    Angiotensin I converting enzyme (ACE) inhibitory and antioxidant peptides are receiving attention due to their beneficial effects in the prevention/treatment of hypertension. The objective was to explore the effect of high hydrostatic pressure (HP) on proteolysis by different proteases and the release of bioactive peptides from lentil proteins. Pressurisation (100-300 MPa) enhanced the hydrolytic efficiency of Protamex, Savinase and Corolase 7089 compared to Alcalase. Proteolysis at 300 MPa led to a complete degradation of lentil proteins and increased peptide (antioxidant activities that were retained upon in vitro gastrointestinal digestion. The peptides responsible for the multifunctional properties of S300 hydrolysate were identified as different fragments from storage proteins and the allergen Len c 1. These results support the potential of HP as a technology for the cost-effective production of bioactive peptides from lentil proteins during enzymatic proteolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Prevention of oxLDL uptake leads to decreased atherosclerosis in hematopoietic NPC1-deficient Ldlr(-/-) mice.

    Science.gov (United States)

    Jeurissen, Mike L J; Walenbergh, Sofie M A; Houben, Tom; Gijbels, Marion J J; Li, Jieyi; Hendrikx, Tim; Oligschlaeger, Yvonne; van Gorp, Patrick J; Binder, Christoph J; Donners, Marjo M P C; Shiri-Sverdlov, Ronit

    2016-12-01

    Atherosclerosis is a chronic inflammatory disease of medium and large vessels and is typically characterized by the predominant accumulation of low-density lipoprotein (LDL)-cholesterol inside macrophages that reside in the vessel walls. Previous studies clearly demonstrated an association specifically between the oxidized type of LDL (oxLDL) and atherosclerotic lesion formation. Further observations revealed that these atherosclerotic lesions displayed enlarged, lipid-loaded lysosomes. By increasing natural antibodies against oxLDL, pneumococcal vaccination has been shown to reduce atherosclerosis in LDL receptor knockout (Ldlr(-/-)) mice. Relevantly, loss of the lysosomal membrane protein Niemann-Pick Type C1 (NPC1) led to lysosomal accumulation of various lipids and promoted atherosclerosis. Yet, the importance of lysosomal oxLDL accumulation inside macrophages, compared to non-modified LDL, in atherosclerosis has never been established. By transplanting NPC1 bone marrow into lethally irradiated Ldlr(-/-) mice, a hematopoietic mouse model for lysosomal cholesterol accumulation was created. Through injections with heat-inactivated pneumococci, we aimed to demonstrate the specific contribution of lysosomal oxLDL accumulation inside macrophages in atherosclerosis development. While there were no differences in plaque morphology, a reduction in plaque size and plaque inflammation was found in immunized NPC1(mut)-transplanted mice, compared to non-immunized NPC1(mut)-transplanted mice. Lysosomal oxLDL accumulation within macrophages contributes to murine atherosclerosis. Future intervention strategies should focus specifically on preventing oxLDL, unlike non-modified LDL, from being internalized into lysosomes. Such an intervention can have an additive effect to current existing treatments against atherosclerosis. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  2. HPLC-DAD Analysis and In-Vitro Property of Polyphenols Extracts from (Solanum Aethiopium) Fruits on α -Amylase, α -Glucosidase and Angiotensin - 1- Converting Enzyme Activities.

    Science.gov (United States)

    Nwanna, E E; Ibukun, E O; Oboh, G; Ademosun, A O; Boligon, A A; Athayde, M

    2014-12-01

    Garden egg (Solanum aethiopium) is an edible fruits vegetable with  different species.This study investigated characterisation and the effect of the phenolics extracts from S. aethiopium species with enzymes linked with type -2-diabetes (α-amylase and α-glucosidase) and hypertension [Angiotensin-1-converting enzyme (ACE)]. Fresh samples of the 5 species of the garden egg namely, [Solanum gilo (PW), Solanum torvum (TWS), Solanum kumba (PGR), Solanum incanum (GSB), and Solanum indicum (WSB)] were oven-dried at 50°C and milled into flour. The aqueous extracts were prepared (1:50 w/v). The phenolic contents (total phenol and total flavonoid), vitamin C and 1,1-diphenyl-2-picrylhydrazyl (DPPH), the antioxidant activities of the extracts were evaluated. The ability of the extracts to inhibit diabetes enzymes in rat pancreas as well as the inhibition of angiotensin-1-converting (ACE) enzyme in lungs homogenates in vitro were investigated. Furthermore, the fruits polyphenols were identified and quantified using HPLC-DAD. The phenolic contents ranged from 2.70-3.76 mgGAE/g, while there were no significant (P>0.05) differences in their flavonoid content and ability to reduce Fe(3+) to Fe(2+). The vitamin C contents of the species ranged from 4.01-6.52 mg/ml. The extracts scavenged DPPH in a dose dependent manner with the IC50 values ranging from 3.23-4.20 mg/ml. Furthermore, the extracts showed strong inhibition of α-glucosidase, mild inhibition of α-amylase and strong inhibition of ACE activities. This study showed that the inhibition of the key enzymes relevant to type-2 diabetes and hypertension could be part of the mechanisms by which garden egg manage/prevent the degenerative conditions.

  3. Extraction temperature affects the activities of antioxidation, carbohydrate-digestion enzymes, and angiotensin-converting enzyme of Pleurotus citrinopileatus extract

    OpenAIRE

    Chen, Pao-Huei; Weng, Yih-Ming; Yu, Zer-Ran; Koo, Malcolm; Wang, Be-Jen

    2016-01-01

    Extraction temperature can potentially affect the chemical compositions and bioactivities of the extracts obtained. The objective of this study was to investigate the effect of extraction temperature on the distribution of bioactive compounds and the bioactivities of Pleurotus citrinopileatus. The antioxidant activities (2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)+ scavenging capabilities) and the inhibitory capabilities on pancreatic α-amylase, in...

  4. Utilisation of rapeseed protein isolates for production of peptides with angiotensin I-converting enzyme (ACE-inhibitory activity

    Directory of Open Access Journals (Sweden)

    Vioque, Javier

    2004-12-01

    Full Text Available ACE activity is related to increased arterial pressure and coronary diseases. A rapeseed protein isolate was hydrolyzed with the protease Alcalase in order to investigate the possible presence of ACE inhibitory peptides in the resulting hydrolysates. Hydrolysis for 30 min yielded a hydrolysate with the highest ACE inhibitory activity. Two fractions of this hydrolysate obtained by Biogel P2 gel filtration chromatography were used for further purification of ACE inhibitory peptides. Three fractions with ACE inhibitory activity were purified by reverse-phase HPLC of Biogel P2 f ractions. This demonstrates that rapeseed protein hydrolysates represent a good source of ACE inhibitory peptides .La actividad de ECA está relacionada con una presión arterial alta y enfermedades cardíacas. Un aislado proteico de colza se hidrolizó con alcalasa para estudiar la posible presencia de péptidos inhibidores de ECA en el hidrolizado. La hidrólisis durante 30 min produjo el hidrolizado con la mayor actividad inhibidora de ECA. Dos fracciones de este hidrolizado, obtenidas por cromatografía de filtración en gel Biogel P2, se usaron para la purificación de péptidos inhibidores de ECA. Tres fracciones con actividad inhibidora de ECA se purificaron mediante HPLC en fase reversa de las fracciones obtenidas mediante Biogel P2. Esto demuestra que los hidrolizados proteicos de colza representan una buena fuente de péptidos inhibidores de ECA.

  5. Osteoanabolic activity of whey-derived anti-oxidative (MHIRL and YVEEL) and angiotensin-converting enzyme inhibitory (YLLF, ALPMHIR, IPA and WLAHK) bioactive peptides.

    Science.gov (United States)

    Pandey, Masum; Kapila, Rajeev; Kapila, Suman

    2017-11-06

    Exploring bone rebuilding anabolic agents has been gaining much attention due to their potential therapeutic effects in treating several bone disorders including osteoporosis. Whey protein has been reported to affect bone health osteoanabolically, in terms of proliferation and differentiation of primary osteoblast cells. This study investigates whether whey derived anti-oxidative (AO) (P1- MHIRL, P2- YVEEL) and angiotensin converting enzyme inhibitory (ACE inhibitory) (P3- YLLF, P4-ALPMHIR, P5-IPA, P6- WLAHK) bioactive peptides affect the proliferation and differentiation of primary osteoblast cells isolated from rat calvaria. The proliferation and osteogenic activity of osteoblast cells in presence of these peptides were determined by MTT assay, DNA quantification study, Alkaline phosphatase activity (ALP) and ALP staining, Alizarin red activity and staining, and secretory osteocalcin measurement. The expression of osteogenesis-related genes (COLI-α, ALP, OCN and RUNX2) were determined by real-time quantitative PCR (RT-PCR) analysis over a period of 21days. The peptide treated osteoblasts showed a significant increase in viable cell density and proliferation in the order of P2>P6>P3 at optimised concentration. Furthermore, the osteoblastic differentiation markers in response to these peptides were found to be significantly up regulated in the order of P2>P6>P3 when compared to the controls. These results demonstrated that bioactive whey-derived AO and ACE inhibitory peptides can play a potential therapeutic role in osteoporosis by activating osteoblasts anabolically. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Power converters definitions, classification and converter topologies

    CERN Document Server

    Bordry, Frederick

    2006-01-01

    This paper introduces power conversion principles and defines the terminology. The concepts of sources and switches are defined and classified. From the basic laws of source interconnections, a generic method of power converter synthesis is presented. Some examples illustrate this systematic method. Finally, the notions of commutation cell and soft commutation are introduced and discussed.

  7. Lifetime Estimation of DC-link Capacitors in a Single-phase Converter with an Integrated Active Power Decoupling Module

    DEFF Research Database (Denmark)

    Ma, Siyuan; Wang, Haoran; Tang, Junchaojie

    2016-01-01

    In single-phase inverters, DC-link capacitors are installed at the DC-link to buffer the ripple power between the AC side and DC side. Active decoupling methods introduce additional circuits at the DC side or AC side to partially or fully supply the ripple power. So that the demanded DC-link capa...... at the DC side and AC side, respectively. The ripple current spectrum of the capacitors is obtained by double Fourier analysis of a H-bridge inverter with natural sampling PWM modulation. A study case is demonstrated by a 2,000 W H-bridge inverter with 400 V DC-link voltage.......-link capacitor capacitance can be decreased. However, few research is about the effect of DC side and AC side decoupling on the DC-link capacitor reliability considering its electro-thermal stresses. This paper presents a quantitative analysis on the lifetime of capacitors with power decoupling circuits...

  8. Systematic Design of the Lead-Lag Network Method for Active Damping in LCL-Filter Based Three Phase Converters

    DEFF Research Database (Denmark)

    Alzola, Rafael Pena; Liserre, Marco; Blaabjerg, Frede

    2014-01-01

    ) nor its rationale has been explained. Thus, in this paper a straightforward procedure is developed to tune the lead-lag network with the help of software tools. The rationale of this procedure, based on the capacitor current feedback, is elucidated. Stability is studied by means of the root locus......Three-phase active rectifiers guarantee sinusoidal input currents and unity power factor at the price of a high switching frequency ripple. To adopt an LCL-filter, instead of an L-filter, allows using reduced values for the inductances and so preserving dynamics. However, stability problems can...... without using dissipative elements but, sometimes, needing additional sensors. This solution has been addressed in many publications. The lead-lag network method is one of the first reported procedures and continues being in use. However, neither there is a direct tuning procedure (without trial and error...

  9. Fermentation characteristics and angiotensin I-converting enzyme-inhibitory activity of Lactobacillus helveticus isolate H9 in cow milk, soy milk, and mare milk.

    Science.gov (United States)

    Wang, Jicheng; Li, Changkun; Xue, Jiangang; Yang, Jie; Zhang, Qing; Zhang, Heping; Chen, Yongfu

    2015-06-01

    Lactobacillus helveticus isolate H9 demonstrated high angiotensin I-converting enzyme (ACE)-inhibitory activity in previous research. Here, we evaluated the fermentation characteristics (pH, titratable acidity, free amino nitrogen, and viable bacterial counts), ACE-inhibitory activity, and contents of Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP) peptides of stored yogurt (4°C for 28 d) fermented by L. helveticus isolate H9 (initially inoculated at 4 concentrations), from cow, mare, and soy milks. During storage, the pH and titratable acidity remained stable in yogurts produced from all milk types and all inoculation concentrations. The viable bacterial counts in all stored yogurts ranged between 10(6.72) and 10(8.59) cfu/g. The highest ACE-inhibitory activity (70.9-74.5%) was achieved at inoculation concentrations of 5×10(6) cfu/mL. The ACE-inhibitory tripeptides VPP and IPP as determined by ultra-performance liquid chromatography-tandem mass spectrometry were not produced in yogurt made from soy milk or mare milk. These evaluations indicate that L. helveticus H9 has good probiotic properties and would be a promising candidate for production of fermented food with probiotic properties. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  10. Short communication: Potential of Fresco-style cheese whey as a source of protein fractions with antioxidant and angiotensin-I-converting enzyme inhibitory activities.

    Science.gov (United States)

    Tarango-Hernández, S; Alarcón-Rojo, A D; Robles-Sánchez, M; Gutiérrez-Méndez, N; Rodríguez-Figueroa, J C

    2015-11-01

    Recently, traditional Mexican Fresco-style cheese production has been increasing, and the volume of cheese whey generated represents a problem. In this study, we investigated the chemical composition of Fresco-style cheese wheys and their potential as a source of protein fractions with antioxidant and angiotensin-I-converting enzyme (ACE)-inhibitory activities. Three samples from Fresco, Panela, and Ranchero cheeses whey were physicochemically characterized. Water-soluble extracts were fractionated to obtain whey fractions with different molecular weights: 10-5, 5-3, 3-1 and cheese wheys. All whey fractions had antioxidant and ACE-inhibitory activities. The 10-5 kDa whey fraction of Ranchero cheese had the highest Trolox equivalent antioxidant capacity (0.62 ± 0.00 mM), and the 3-1 kDa Panela and Fresco cheese whey fractions showed the highest ACE-inhibitory activity (0.57 ± 0.02 and 0.59 ± 0.04 μg/mL 50%-inhibitory concentration values, respectively). These results suggest that Fresco-style cheese wheys may be a source of protein fractions with bioactivity, and thus could be useful ingredients in the manufacture of functional foods with increased nutritional value. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  11. Evidence for an interleukin-1beta converting enzyme (ICE)-like activity distinct from ICE and responsible for ICE and CPP32 cleavage during apoptosis.

    Science.gov (United States)

    Miossec, C; Dutilleul, V; Durand, L; Faucheu, C; Pilatre, L; Golec, J; Fassy, F; Diu-Hercend, A

    1997-01-01

    IL-1beta converting enzyme (ICE) and ICE-related proteases (IRPs) have been suggested to play a central role in apoptosis. We report the use of peptidic ICE inhibitors to reassess the role of this enzyme in the apoptosis induced by Fas or TNFalpha receptor ligation in Jurkat cells, U937 cells or monocytes. Our results show that inhibition of IL-1beta processing can be dissociated from inhibition of apoptosis. Indeed, two out of three com-pounds active on ICE are not inhibitory for apoptosis. This shows that ICE is not required for progression in the apoptotic pathway, but that one or several IRPs are necessary. In addition, Western blot analysis of cell lysates shows that both ICE and CPP32 precursors disappear rapidly after apoptosis induction, while ICH-1L precursor remains intact. Concomitant appearance of cleavage products can be visualized for CPP32, but not for ICE, suggesting that the former is proteolytically activated. In addition, this precursor cleavage can be blocked by an ICE inhibitor active on apoptosis. Altogether, our data support the hypothesis that one or several IRPs are necessary for apoptosis and are responsible for ICE and CPP32 cleavage during this process.

  12. Investigation of lactic acid bacterial strains for meat fermentation and the product's antioxidant and angiotensin-I-converting-enzyme inhibitory activities.

    Science.gov (United States)

    Takeda, Shiro; Matsufuji, Hisashi; Nakade, Koji; Takenoyama, Shin-Ichi; Ahhmed, Abdulatef; Sakata, Ryoichi; Kawahara, Satoshi; Muguruma, Michio

    2017-03-01

    In the lactic acid bacteria (LAB) strains screened from our LAB collection, Lactobacillus (L.) sakei strain no. 23 and L. curvatus strain no. 28 degraded meat protein and tolerated salt and nitrite in vitro. Fermented sausages inoculated strains no. 23 and no. 28 showed not only favorable increases in viable LAB counts and reduced pH, but also the degradation of meat protein. The sausages fermented with these strains showed significantly higher antioxidant activity than those without LAB or fermented by each LAB type strain. Angiotensin-I-converting-enzyme (ACE) inhibitory activity was also significantly higher in the sausages fermented with strain no. 23 than in those fermented with the type strain. Higher ACE inhibitory activity was also observed in the sausages fermented with strain no. 28, but did not differ significantly from those with the type strain. An analysis of the proteolysis and degradation products formed by each LAB in sausages suggested that those bioactivities yielded fermentation products such as peptides. Therefore, LAB starters that can adequately ferment meat, such as strains no. 23 and no. 28, should contribute to the production of bioactive compounds in meat products. © 2016 Japanese Society of Animal Science.

  13. Novel NPC1 mutations with different segregation in two related Greek patients with Niemann-Pick type C disease: molecular study in the extended pedigree and clinical correlations.

    Science.gov (United States)

    Bountouvi, Evangelia; Papadopoulou, Anna; Vanier, Marie T; Nyktari, Georgia; Kanellakis, Spyridon; Michelakakis, Helen; Dinopoulos, Argyrios

    2017-05-04

    Niemann-Pick type C disease (NPC) is an autosomal recessive, neurovisceral, lysosomal storage disorder with protean and progressive clinical manifestations, resulting from mutations in either of the two genes, NPC1 (~95% of families) and NPC2. Contrary to other populations, published evidence regarding NPC disease in Greece is sparse. The study population consisted of two Greek NPC patients and their extended pedigree. Patients' clinical, biochemical, molecular profiles and the possible correlations are presented. Genotyping was performed by direct sequencing. Mutations' origin was investigated through selected exonic NPC1 polymorphisms encountered more frequently in a group of 37 Greek patients with clinical suspicion of NPC disease and in a group of 90 healthy Greek individuals, by the use of Haplore software. Two novel NPC1 mutations, [IVS23 + 3insT (c.3591 + 3insT) and p. K1057R (c.3170A > C)] were identified and each mutation was associated with a specific haplotype. One of the patients was entered to early treatment with miglustat and has presented no overt neurological impairment after 11.5 years. The splicing mutation IVS23 + 3insT was associated in homozygocity with a severe biochemical and clinical phenotype. A possible founder effect for this mutation was demonstrated in the Greek Island, as well as a different origin for each novel mutation. Longitudinal follow-up may contribute to clarify the possible effect of early miglustat therapy on the patient compound heterozygous for the two novel mutations.

  14. An L213A variant of β-glycosidase from Sulfolobus solfataricus with increased α-L-arabinofuranosidase activity converts ginsenoside Rc to compound K.

    Directory of Open Access Journals (Sweden)

    Ji-Hyeon Choi

    Full Text Available Compound K (C-K is a crucial pharmaceutical and cosmetic component because of disease prevention and skin anti-aging effects. For industrial application of this active compound, the protopanaxadiol (PPD-type ginsenosides should be transformed to C-K. β-Glycosidase from Sulfolobus solfataricus has been reported as an efficient C-K-producing enzyme, using glycosylated PPD-type ginsenosides as substrates. β-Glycosidase from S. solfataricus can hydrolyze β-d-glucopyranoside in ginsenosides Rc, C-Mc1, and C-Mc, but not α-l-arabinofuranoside in these ginsenosides. To determine candidate residues involved in α-l-arabinofuranosidase activity, compound Mc (C-Mc was docking to β-glycosidase from S. solfataricus in homology model and sequence was aligned with β-glycosidase from Pyrococcus furiosus that has α-l-arabinofuranosidase activity. A L213A variant β-glycosidase with increased α-l-arabinofuranosidase activity was selected by substitution of other amino acids for candidate residues. The increased α-l-arabinofuranosidase activity of the L213A variant was confirmed through the determination of substrate specificity, change in binding energy, transformation pathway, and C-K production from ginsenosides Rc and C-Mc. The L213A variant β-glycosidase catalyzed the conversion of Rc to Rd by hydrolyzing α-l-arabinofuranoside linked to Rc, whereas the wild-type β-glycosidase did not. The variant enzyme converted ginsenosides Rc and C-Mc into C-K with molar conversions of 97%, which were 1.5- and 2-fold higher, respectively, than those of the wild-type enzyme. Therefore, protein engineering is a useful tool for enhancing the hydrolytic activity on specific glycoside linked to ginsenosides.

  15. High speed data converters

    CERN Document Server

    Ali, Ahmed MA

    2016-01-01

    This book covers high speed data converters from the perspective of a leading high speed ADC designer and architect, with a strong emphasis on high speed Nyquist A/D converters. For our purposes, the term 'high speed' is defined as sampling rates that are greater than 10 MS/s.

  16. Electrical Power Converter

    NARCIS (Netherlands)

    Ferreira, J.A.

    2014-01-01

    Electrical power converter for converting electrical power of a power source connected or connectable at an input to electrical DC-power at an output, wherein between the input and the output a first circuit of submodules is provided, wherein said first circuit of submodules and the power source

  17. Digital to Analog Converter

    NARCIS (Netherlands)

    Westra, Jan R.; Annema, Anne J.; van den Boom, Jeroen M.; Dijkmans, Eise C.

    2001-01-01

    A digital to analog converter (DAC) for converting a digital signal (DS) having a maximum voltage range which corresponds to a first supply voltage (UL) into an analog signal (UOUT) having a maximum voltage range which corresponds to a second supply voltage (UH). The first supply voltage (UL) is

  18. Digital to Analog Converter

    NARCIS (Netherlands)

    Westra, Jan R.; Annema, Anne J.; van den Boom, Jeroen M.; Dijkmans, Eise C.

    2006-01-01

    A digital to analog converter (DAC) for converting a digital signal (DS) having a maximum voltage range which corresponds to a first supply voltage (UL) into an analog signal (UOUT) having a maximum voltage range which corresponds to a second supply voltage (UH). The first supply voltage (UL) is

  19. Bidirectional converter interface for a battery energy storage test bench

    DEFF Research Database (Denmark)

    Trintis, Ionut; Thomas, Stephan; Blank, Tobias

    2011-01-01

    This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation...... ratio. The dc-dc converter controls the battery charge/discharge current while the grid converter controls the common dc-link voltage and the grid current. The applied control structures and the hardware implementation of both converters are presented, together with their interaction. Experimental...

  20. Reduction of blood pressure by aronia berries through inhibition of angiotensin-converting enzyme activity in the spontaneously hypertensive rat kidney

    Directory of Open Access Journals (Sweden)

    Takuya Yamane

    2017-04-01

    Full Text Available Background: Aronia berries contain many important effects on potential health, with previous studies suggesting that aronia juice is useful for the treatment of hypertension. Objective:To examine whether aronia berries have improvement effects on hypertension through the inhibition of angiotensin-converting enzyme (ACEactivity.Method:The normal diet containing 10% freeze-dried aronia berries was administered to five spontaneously hypertensive rats (SHRs in each group for 28 days, with their body weight, food intake,and systolic blood pressure being measured. At 28 days after administration of aronia berry-containing diets, the serum, lungs,and kidneys were isolated and used for measurement of ACE activity.Results:In this study, we found that blood pressure in SHRs fed freeze-dried aronia berries-containing diet decreased compared with the blood pressure in SHRs fed normal diet. We also discovered that the catalytic activity of ACE was reduced in the kidney of SHRs fed freeze-dried aronia berries-containing diet but not in the lungs of aronia berries-administered rats. Conclusion: Aronia berries have beneficial effects on the amelioration of hypertension through inhibition of the kidney renin-angiotensin system.

  1. Flavonoids from the buds of Rosa damascena inhibit the activity of 3-hydroxy-3-methylglutaryl-coenzyme a reductase and angiotensin I-converting enzyme.

    Science.gov (United States)

    Kwon, Eun-Kyung; Lee, Dae-Young; Lee, Hyungjae; Kim, Dae-Ok; Baek, Nam-In; Kim, Young-Eon; Kim, Hae-Yeong

    2010-01-27

    Rosa damascena has been manufactured as various food products, including tea, in Korea. A new flavonoid glycoside, kaempferol-3-O-beta-D-glucopyranosyl(1-->4)-beta-D-xylopyranoside, named roxyloside A was isolated from the buds of this plant, along with four known compounds, isoquercitrin, afzelin, cyanidin-3-O-beta-glucoside, and quercetin gentiobioside. The chemical structures of these compounds were determined by spectroscopic analyses, including FAB-MS, UV, IR, (1)H and (13)C NMR, DEPT, and 2D NMR (COSY, HSQC, and HMBC). All the isolated compounds except cyanidin-3-O-beta-glucoside exhibited high levels of inhibitory activity against 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase with IC(50) values ranging from 47.1 to 80.6 microM. Cyanidin-3-O-beta-glucoside significantly suppressed angiotensin I-converting enzyme (ACE) activity, with an IC(50) value of 138.8 microM, while the other four compounds were ineffective. These results indicate that R. damascena and its flavonoids may be effective to improve the cardiovascular system.

  2. Acute effects of angiotensin-converting enzyme inhibition versus angiotensin II receptor blockade on cardiac sympathetic activity in patients with heart failure.

    Science.gov (United States)

    Azevedo, Eduardo R; Mak, Susanna; Floras, John S; Parker, John D

    2017-10-01

    The beneficial effects of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II (ANG II) receptor antagonists in patients with heart failure secondary to reduced ejection fraction (HFrEF) are felt to result from prevention of the adverse effects of ANG II on systemic afterload and renal homeostasis. However, ANG II can activate the sympathetic nervous system, and part of the beneficial effects of ACE inhibitors and ANG II antagonists may result from their ability to inhibit such activation. We examined the acute effects of the ACE inhibitor captopril (25 mg, n = 9) and the ANG II receptor antagonist losartan (50 mg, n = 10) on hemodynamics as well as total body and cardiac norepinephrine spillover in patients with chronic HFrEF. Hemodynamic and neurochemical measurements were made at baseline and at 1, 2, and 4 h after oral dosing. Administration of both drugs caused significant reductions in systemic arterial, cardiac filling, and pulmonary artery pressures ( P < 0.05 vs. baseline). There was no significant difference in the magnitude of those hemodynamic effects. Plasma concentrations of ANG II were significantly decreased by captopril and increased by losartan ( P < 0.05 vs. baseline for both). Total body sympathetic activity increased in response to both captopril and losartan ( P < 0.05 vs. baseline for both); however, there was no change in cardiac sympathetic activity in response to either drug. The results of the present study do not support the hypothesis that the acute inhibition of the renin-angiotensin system has sympathoinhibitory effects in patients with chronic HFrEF. Copyright © 2017 the American Physiological Society.

  3. CD40 agonist converting CTL exhaustion via the activation of the mTORC1 pathway enhances PD-1 antagonist action in rescuing exhausted CTLs in chronic infection.

    Science.gov (United States)

    Xu, Aizhang; Wang, Rong; Freywald, Andrew; Stewart, Kristoffor; Tikoo, Suresh; Xu, Jianqing; Zheng, Changyu; Xiang, Jim

    2017-03-11

    Expansion of PD-1-expressing CD8 + cytotoxic T lymphocytes (CTLs) and associated CTL exhaustion are chief issues for ineffective virus-elimination in chronic infectious diseases. PD-1 blockade using antagonistic anti-PD-L1 antibodies results in a moderate conversion of CTL exhaustion. We previously demonstrated that CD40L signaling of ovalbumin (OVA)-specific vaccine, OVA-Texo, converts CTL exhaustion via the activation of the mTORC1 pathway in OVA-expressing adenovirus (AdVova)-infected B6 mice showing CTL inflation and exhaustion. Here, we developed AdVova-infected B6 and transgenic CD11c-DTR (termed AdVova-B6 and AdVova-CD11c-DTR) mice with chronic infection, and assessed a potential effect of CD40 agonist on the conversion of CTL exhaustion and on a potential enhancement of PD-1 antagonist action in rescuing exhausted CTLs in our chronic infection models. We demonstrate that a single dose of anti-CD40 alone can effectively convert CTL exhaustion by activating the mTORC1 pathway, leading to CTL proliferation, up-regulation of an effector-cytokine IFN-γ and the cytolytic effect in AdVova-B6 mice. Using anti-CD4 antibody and diphtheria toxin (DT) to deplete CD4 + T-cells and dendritic cells (DCs), we discovered that the CD40 agonist-induced conversion in AdVova-B6 and AdVova-CD11c-DTR mice is dependent upon host CD4 + T-cell and DC involvements. Moreover, CD40 agonist significantly enhances PD-1 antagonist effectiveness in rescuing exhausted CTLs in chronic infection. Taken together, our data demonstrate the importance of CD40 signaling in the conversion of CTL exhaustion and its ability to enhance PD-1 antagonist action in rescuing exhausted CTLs in chronic infection. Therefore, our findings may positively impact the design of new therapeutic strategies for chronic infectious diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Microminiature thermionic converters

    Science.gov (United States)

    King, Donald B.; Sadwick, Laurence P.; Wernsman, Bernard R.

    2001-09-25

    Microminiature thermionic converts (MTCs) having high energy-conversion efficiencies and variable operating temperatures. Methods of manufacturing those converters using semiconductor integrated circuit fabrication and micromachine manufacturing techniques are also disclosed. The MTCs of the invention incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. Existing prior art thermionic converter technology has energy conversion efficiencies ranging from 5-15%. The MTCs of the present invention have maximum efficiencies of just under 30%, and thousands of the devices can be fabricated at modest costs.

  5. Improving Power Converter Reliability

    DEFF Research Database (Denmark)

    Ghimire, Pramod; de Vega, Angel Ruiz; Beczkowski, Szymon

    2014-01-01

    The real-time junction temperature monitoring of a high-power insulated-gate bipolar transistor (IGBT) module is important to increase the overall reliability of power converters for industrial applications. This article proposes a new method to measure the on-state collector?emitter voltage...... of a high-power IGBT module during converter operation, which may play a vital role in improving the reliability of the power converters. The measured voltage is used to estimate the module average junction temperature of the high and low-voltage side of a half-bridge IGBT separately in every fundamental...

  6. Corneal alterations during combined therapy with cyclodextrin/allopregnanolone and miglustat in a knock-out mouse model of NPC1 disease.

    Directory of Open Access Journals (Sweden)

    Marine Hovakimyan

    Full Text Available BACKGROUND: Niemann Pick disease type C1 is a neurodegenerative disease caused by mutations in the NPC1 gene, which result in accumulation of unesterified cholesterol and glycosphingolipids in the endosomal-lysosomal system as well as limiting membranes. We have previously shown the corneal involvement in NPC1 pathology in form of intracellular inclusions in epithelial cells and keratocytes. The purpose of the present study was to clarify if these inclusions regress during combined substrate reduction- and by-product therapy (SRT and BPT. METHODOLOGY/PRINCIPAL FINDINGS: Starting at postnatal day 7 (P7 and thereafter, NPC1 knock-out mice (NPC1(-/- and wild type controls (NPC1(+/+ were injected with cyclodextrin/allopregnanolone weekly. Additionally, a daily miglustat injection started at P10 until P23. Starting at P23 the mice were fed powdered chow with daily addition of miglustat. The sham group was injected with 0.9% NaCl at P7, thereafter daily starting at P10 until P23, and fed powdered chow starting at P23. For corneal examination, in vivo confocal laser-scanning microscopy (CLSM was performed one day before experiment was terminated. Excised corneas were harvested for lipid analysis (HPLC/MS and electron microscopy. In vivo CLSM demonstrated a regression of hyperreflective inclusions in all treated NPC1(-/-mice. The findings varied between individual mice, demonstrating a regression, ranging from complete absence to pronounced depositions. The reflectivity of inclusions, however, was significantly lower when compared to untreated and sham-injected NPC1(-/- mice. These confocal findings were confirmed by lipid analysis and electron microscopy. Another important CLSM finding revealed a distinct increase of mature dendritic cell number in corneas of all treated mice (NPC1(-/- and NPC1(+/+, including sham-treated ones. CONCLUSIONS/SIGNIFICANCE: The combined substrate reduction- and by-product therapy revealed beneficial effects on the cornea

  7. Sex differences in renal angiotensin converting enzyme 2 (ACE2 activity are 17β-oestradiol-dependent and sex chromosome-independent

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2010-11-01

    Full Text Available Abstract Background Angotensin converting enzyme 2 (ACE2 is a newly discovered monocarboxypeptidase that counteracts the vasoconstrictor effects of angiotensin II (Ang II by converting Ang II to Ang-(1-7 in the kidney and other tissues. Methods ACE2 activity from renal homogenates was investigated by using the fluorogenic peptide substrate Mca-YVADAPK(Dnp-OH, where Mca is (7-methoxycoumarin-4-yl-acetyl and Dnp is 2,4-dinitrophenyl. Results We found that ACE2 activity expressed in relative fluorescence units (RFU in the MF1 mouse is higher in the male (M compared to the female (F kidney [ACE2 (RFU/min/μg protein: M 18.1 ± 1.0 versus F 11.1 ± 0.39; P n = 6]. Substrate concentration curves revealed that the higher ACE2 activity in the male was due to increased ACE2 enzyme velocity (Vmax rather than increased substrate affinity (Km. We used the four core genotypes mouse model in which gonadal sex (ovaries versus testes is separated from the sex chromosome complement enabling comparisons among XX and XY gonadal females and XX and XY gonadal males. Renal ACE2 activity was greater in the male than the female kidney, regardless of the sex chromosome complement [ACE2 (RFU/min/μg protein: intact-XX-F, 7.59 ± 0.37; intact-XY-F, 7.43 ± 0.53; intact-XX-M, 12.1 ± 0.62; intact-XY-M, 12.7 ± 1.5; n = 4-6/group; P n = 6/group]. 17β-oestradiol (E2 treatment of GDX mice resulted in ACE2 activity that was only 40% of the activity found in the GDX mice, regardless of their being male or female, and was independent of the sex chromosome complement [ACE2 (RFU/min/μg protein: GDX+E2-XX-F, 5.56 ± 1.0; GDX+E2-XY-F, 4.60 ± 0.52; GDX+E2-XX-M, 5.35 ± 0.70; GDX+E2-XY-M, 5.12 ± 0.47; n = 6/group]. Conclusions Our findings suggest sex differences in renal ACE2 activity in intact mice are due, at least in part, to the presence of E2 in the ovarian hormone milieu and not to the testicular milieu or to differences in sex chromosome dosage (2X versus 1X; 0Y versus 1Y

  8. Niemann-Pick Type C2 Protein Mediates Hepatic Stellate Cells Activation by Regulating Free Cholesterol Accumulation

    Directory of Open Access Journals (Sweden)

    Yuh-Ching Twu

    2016-07-01

    Full Text Available In chronic liver diseases, regardless of their etiology, the development of fibrosis is the first step toward the progression to cirrhosis, portal hypertension, and hepatocellular carcinoma. Hepatic stellate cells (HSCs are the main profibrogenic cells that promote the pathogenesis of liver fibrosis, and so it is important to identify the molecules that regulate HSCs activation and liver fibrosis. Niemann-Pick type C2 (NPC2 protein plays an important role in the regulation of intracellular cholesterol homeostasis by directly binding with free cholesterol. However, the roles of NPC2 in HSCs activation and liver fibrosis have not been explored in detail. Since a high-cholesterol diet exacerbates liver fibrosis progression in both rodents and humans, we propose that the expression of NPC2 affects free cholesterol metabolism and regulates HSCs activation. In this study, we found that NPC2 is decreased in both thioacetamide- and carbon tetrachloride-induced liver fibrosis tissues. In addition, NPC2 is expressed in quiescent HSCs, but its activation status is down-regulated. Knockdown of NPC2 in HSC-T6 cells resulted in marked increases in transforming growth factor-β1 (TGF-β1-induced collagen type 1 α1 (Col1a1, α-smooth muscle actin (α-SMA expression, and Smad2 phosphorylation. In contrast, NPC2 overexpression decreased TGF-β1-induced HSCs activation. We further demonstrated that NPC2 deficiency significantly increased the accumulation of free cholesterol in HSCs, increasing Col1a1 and α-SMA expression and activating Smad2, and leading to sensitization of HSCs to TGF-β1 activation. In contrast, overexpression of NPC2 decreased U18666A-induced free cholesterol accumulation and inhibited the subsequent HSCs activation. In conclusion, our study has demonstrated that NPC2 plays an important role in HSCs activation by regulating the accumulation of free cholesterol. NPC2 overexpression may thus represent a new treatment strategy for liver fibrosis.

  9. Microsatellite CONVERT Input File

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Microsatellite data formatted for the software CONVERT, which includes dataset numerical IDs, sampling site names, and locus identifiers. Rows 291-294 provides...

  10. Angiotensin I-Converting Enzyme (ACE Inhibitory Activity, Antioxidant Properties, Phenolic Content and Amino Acid Profiles of Fucus spiralis L. Protein Hydrolysate Fractions

    Directory of Open Access Journals (Sweden)

    Lisete Paiva

    2017-10-01

    Full Text Available Food protein-derived hydrolysates with multi-bioactivities such as antihypertensive and antioxidant properties have recently received special attention since both activities can play significant roles in preventing cardiovascular diseases. This study reports, for the first time, the angiotensin I-converting enzyme (ACE-inhibition and antioxidant properties of ultrafiltrate fractions (UF with different molecular weight ranges (<1, 1–3 and ≥3 kDa obtained from Fucus spiralis protein hydrolysate (FSPH digested with cellulase–bromelain. The amino acids profile, recovery yield, protein, peptide and total phenolic contents of these FSPH-UF, and the in vitro digestibility of F. spiralis crude protein were also investigated. FSPH-UF ≥3 kDa presented remarkably higher ACE-inhibition, yield, peptide and polyphenolic (phlorotannins contents. Antioxidant analysis showed that FSPH-UF <1 kDa and ≥3 kDa exhibited significantly higher scavenging of 2,2-diphenyl-1-picrylhydrazyl radical and ferrous ion-chelating (FIC activity. FSPH-UF ≥3 kDa had also notably higher ferric reducing antioxidant power (FRAP. Strong correlations were observed between ACE-inhibition and antioxidant activities (FIC and FRAP. The results suggest that ACE-inhibition and antioxidant properties of FSPH-UF may be due to the bioactive peptides and polyphenols released during the enzymatic hydrolysis. In conclusion, this study shows the potential use of defined size FSPH-UF for the prevention/treatment of hypertension and/or oxidative stress-related diseases.

  11. Reduced plasma levels of angiotensin-(1-7 and renin activity in preeclamptic patients are associated with the angiotensin I- converting enzyme deletion/deletion genotype

    Directory of Open Access Journals (Sweden)

    E.P. Velloso

    2007-04-01

    Full Text Available The relationship between preeclampsia and the renin-angiotensin system (RAS is poorly understood. Angiotensin I-converting enzyme (ACE is a key RAS component and plays an important role in blood pressure homeostasis by generating angiotensin II (Ang II and inactivating the vasodilator angiotensin-(1-7 (Ang-(1-7. ACE (I/D polymorphism is characterized by the insertion (I or deletion (D of a 287-bp fragment, leading to changes in ACE activity. In the present study, ACE (I/D polymorphism was correlated with plasma Ang-(1-7 levels and several RAS components in both preeclamptic (N = 20 and normotensive pregnant women (N = 20. The percentage of the ACE DD genotype (60% in the preeclamptic group was higher than that for the control group (35%; however, this percentage was not statistically significant (Fisher exact test = 2.86, d.f. = 2, P = 0.260. The highest plasma ACE activity was observed in the ACE DD preeclamptic women (58.1 ± 5.06 vs 27.6 ± 3.25 nmol Hip-His Leu-1 min-1 mL-1 in DD control patients; P = 0.0005. Plasma renin activity was markedly reduced in preeclampsia (0.81 ± 0.2 vs 3.43 ± 0.8 ng Ang I mL plasma-1 h-1 in DD normotensive patients; P = 0.0012. A reduced plasma level of Ang-(1-7 was also observed in preeclamptic women (15.6 ± 1.3 vs 22.7 ± 2.5 pg/mL in the DD control group; P = 0.0146. In contrast, plasma Ang II levels were unchanged in preeclamptic patients. The selective changes in the RAS described in the present study suggest that the ACE DD genotype may be used as a marker for susceptibility to preeclampsia.

  12. Reduced plasma levels of angiotensin-(1-7 and renin activity in preeclamptic patients are associated with the angiotensin I- converting enzyme deletion/deletion genotype

    Directory of Open Access Journals (Sweden)

    E.P. Velloso

    Full Text Available The relationship between preeclampsia and the renin-angiotensin system (RAS is poorly understood. Angiotensin I-converting enzyme (ACE is a key RAS component and plays an important role in blood pressure homeostasis by generating angiotensin II (Ang II and inactivating the vasodilator angiotensin-(1-7 (Ang-(1-7. ACE (I/D polymorphism is characterized by the insertion (I or deletion (D of a 287-bp fragment, leading to changes in ACE activity. In the present study, ACE (I/D polymorphism was correlated with plasma Ang-(1-7 levels and several RAS components in both preeclamptic (N = 20 and normotensive pregnant women (N = 20. The percentage of the ACE DD genotype (60% in the preeclamptic group was higher than that for the control group (35%; however, this percentage was not statistically significant (Fisher exact test = 2.86, d.f. = 2, P = 0.260. The highest plasma ACE activity was observed in the ACE DD preeclamptic women (58.1 ± 5.06 vs 27.6 ± 3.25 nmol Hip-His Leu-1 min-1 mL-1 in DD control patients; P = 0.0005. Plasma renin activity was markedly reduced in preeclampsia (0.81 ± 0.2 vs 3.43 ± 0.8 ng Ang I mL plasma-1 h-1 in DD normotensive patients; P = 0.0012. A reduced plasma level of Ang-(1-7 was also observed in preeclamptic women (15.6 ± 1.3 vs 22.7 ± 2.5 pg/mL in the DD control group; P = 0.0146. In contrast, plasma Ang II levels were unchanged in preeclamptic patients. The selective changes in the RAS described in the present study suggest that the ACE DD genotype may be used as a marker for susceptibility to preeclampsia.

  13. Epitope mapping of gp350/220 conserved domain of epstein barr virus to develop nasopharyngeal carcinoma (npc) vaccine.

    Science.gov (United States)

    Sitompul, Loly Sabrina; Widodo, Nashi; Djati, M Sasmito; Utomo, Didik H

    2012-01-01

    Nasopharyngeal carcinoma (NPC) is a malignant tumor in the nasopharyngeal epithelial cells that caused by many factors, one of which is the viral infection of EBV (Epstein Barr Virus). The standard treatments to cure NPC still have not been encouraging. The prevention through vaccination is an effective way to stop the disease. However, EBV vaccine being able to cover all variants of virus is still not available yet. Therefore, we identified the conserved region of glycoprotein 350/220 of EBV which has immunogenic and antigenic properties. The glycoprotein 350/220 is viral surface protein responsible to bind CR2 receptor, mediated EBV to enter the host cell. The conserved domain is crucial for EBV in infecting host cells. Further, by blocking CR2 binding domain of gp350/220 using antibody will inhibit EBV's spreading, and provoke an immune system to eliminate the virus in a patient. Glycoprotein 350/220 from all variants of Epstein-Barr virus was retrieved from NCBI. The conserved domain of gp350/220 was identified by aligning the protein sequences and structures. The polymorphic structure was used as a template for docking analysis to identify the resemblance of amino acid from polymorphic variants of gp350/220 that binds CR2. The epitope mapping of gp350/220 was done by Discotope BepiPred method. The result revealed that the conserved region of gp350/220 was predicted to have an epitope, QNPVYLIPETVPYIKWDNC residue, and it does not have any similarities to the human's cell surface protein. Therefore, it can be used as a reference to develop vaccine to prevent NPC.

  14. The Nurse Professional Competence (NPC) Scale: Self-reported competence among nursing students on the point of graduation.

    Science.gov (United States)

    Gardulf, Ann; Nilsson, Jan; Florin, Jan; Leksell, Janeth; Lepp, Margret; Lindholm, Christina; Nordström, Gun; Theander, Kersti; Wilde-Larsson, Bodil; Carlsson, Marianne; Johansson, Eva

    2016-01-01

    International organisations, e.g. WHO, stress the importance of competent registered nurses (RN) for the safety and quality of healthcare systems. Low competence among RNs has been shown to increase the morbidity and mortality of inpatients. To investigate self-reported competence among nursing students on the point of graduation (NSPGs), using the Nurse Professional Competence (NPC) Scale, and to relate the findings to background factors. The NPC Scale consists of 88 items within eight competence areas (CAs) and two overarching themes. Questions about socio-economic background and perceived overall quality of the degree programme were added. In total, 1086 NSPGs (mean age, 28.1 [20-56]years, 87.3% women) from 11 universities/university colleges participated. NSPGs reported significantly higher scores for Theme I "Patient-Related Nursing" than for Theme II "Organisation and Development of Nursing Care". Younger NSPGs (20-27years) reported significantly higher scores for the CAs "Medical and Technical Care" and "Documentation and Information Technology". Female NSPGs scored significantly higher for "Value-Based Nursing". Those who had taken the nursing care programme at upper secondary school before the Bachelor of Science in Nursing (BSN) programme scored significantly higher on "Nursing Care", "Medical and Technical Care", "Teaching/Learning and Support", "Legislation in Nursing and Safety Planning" and on Theme I. Working extra paid hours in healthcare alongside the BSN programme contributed to significantly higher self-reported scores for four CAs and both themes. Clinical courses within the BSN programme contributed to perceived competence to a significantly higher degree than theoretical courses (93.2% vs 87.5% of NSPGs). Mean scores reported by NSPGs were highest for the four CAs connected with patient-related nursing and lowest for CAs relating to organisation and development of nursing care. We conclude that the NPC Scale can be used to identify and measure

  15. Advanced converter technology

    Science.gov (United States)

    Banic, C. V.; Eckhouse, S. A.; Kornbrust, F. J.; Lifman, K.; Peterson, J. L.; Rosati, R. W.; Young, D.

    An advanced converter system for use in electrochemical energy storge was defined. Improved and experimental apparatus are designed to measure these characteristics and to enable better definition of the battery power conditioner interface. Improvement of energy storage system performance through modification of battery converter characteristics is investigated. Power conditioning based on fuel cell use was evaluated. It is concluded that this high switching frequency concept has the potential for significantly reducing the size and cost of battery plant power conditioners.

  16. [The investigation of angiotensin converting enzyme I/D and plasminogen activator inhibitor-1 4G/5G polymorphisms in venous thromboembolism patients].

    Science.gov (United States)

    Kaya, Halide; Karkucak, Mutlu; Salifoğlu, Hatice; Torun, Deniz; Kozan, Salih; Tunca, Yusuf

    2013-01-01

    Deep venous thrombosis and pulmonary embolism, known as venous thromboembolism and seen as a fairly common multifactorial diseases. Differ between populations due to genetic factors, several polymorphisms associated with venous thromboembolism was conducted. As a result of these studies the relationship between disease development and polymorphism is not clear yet. In this study we aimed to investigate the role of angiotensin converting enzyme insersion/deletion (ACE I/D) and plasminogen activator inhibitor-1 4G/5G (PAI-1 4G/5G) polymorphism in the development of disease. In our study, DNA isolated from 80 venous thromboembolism patients and 79 control groups was used. While the classical polymerase chain reaction method used to investigate the ACE I/D polymorphism, the polymerase chain reaction based on allele-specific amplification was used for the detection of PAI-1 4G/5G polymorphism. As a result, there were no significant statistical differences for ACE I/D and PAI-1 4G/5G polymorphism among patient and control groups (p> 0.05). These findings revealed that there is no relationship between these polymorphisms and the development of venous thromboembolism, but large-scale studies are need to be done.

  17. Angiotensin-I converting enzyme inhibitory activity of hydrolysates from oat (Avena sativa) proteins by in silico and in vitro analyses.

    Science.gov (United States)

    Cheung, Imelda W Y; Nakayama, Satoko; Hsu, Monica N K; Samaranayaka, Anusha G P; Li-Chan, Eunice C Y

    2009-10-14

    The potential for producing antihypertensive peptides from oat proteins through enzymatic hydrolysis was assessed in silico and confirmed in vitro. Thermolysin (EC 3.4.24.27) was predicted using BIOPEP database as the enzyme that would theoretically produce the most angiotensin I converting enzyme (ACE) inhibitory peptides from oat. Experimental evidence confirmed that strong ACE-inhibitory activity was produced under various hydrolysis conditions. Hydrolysates produced under high enzyme-to-substrate ratio (3%) short time (20 min) (HEST) and low enzyme-to-substrate ratio (0.1%) long time (120 min) (LELT) conditions had IC(50) values of 30 and 50 microg/mL, respectively. After simulated gastrointestinal digestion, the IC(50) of the HEST hydrolysate was 35 microg/mL whereas the IC(50) of the LELT hydrolysate was higher at 85 microg/mL. Ultrafiltration revealed that potent ACE-inhibitory peptides had molecular weights below 3 kDa. This study demonstrates the usefulness of in silico analysis to select enzymes for hydrolysis of proteins not previously examined as sources of bioactive peptides.

  18. In vitro inhibitory activities of selected Australian medicinal plant extracts against protein glycation, angiotensin converting enzyme (ACE) and digestive enzymes linked to type II diabetes.

    Science.gov (United States)

    Deo, Permal; Hewawasam, Erandi; Karakoulakis, Aris; Claudie, David J; Nelson, Robert; Simpson, Bradley S; Smith, Nicholas M; Semple, Susan J

    2016-11-04

    There is a need to develop potential new therapies for the management of diabetes and hypertension. Australian medicinal plants collected from the Kuuku I'yu (Northern Kaanju) homelands, Cape York Peninsula, Queensland, Australia were investigated to determine their therapeutic potential. Extracts were tested for inhibition of protein glycation and key enzymes relevant to the management of hyperglycaemia and hypertension. The inhibitory activities were further correlated with the antioxidant activities. Extracts of five selected plant species were investigated: Petalostigma pubescens, Petalostigma banksii, Memecylon pauciflorum, Millettia pinnata and Grewia mesomischa. Enzyme inhibitory activity of the plant extracts was assessed against α-amylase, α-glucosidase and angiotensin converting enzyme (ACE). Antiglycation activity was determined using glucose-induced protein glycation models and formation of protein-bound fluorescent advanced glycation endproducts (AGEs). Antioxidant activity was determined by measuring the scavenging effect of plant extracts against 1, 1-diphenyl-2-picryl hydrazyl (DPPH) and using the ferric reducing anti-oxidant potential assay (FRAP). Total phenolic and flavonoid contents were also determined. Extracts of the leaves of Petalostigma banksii and P. pubescens showed the strongest inhibition of α-amylase with IC50 values of 166.50 ± 5.50 μg/mL and 160.20 ± 27.92 μg/mL, respectively. The P. pubescens leaf extract was also the strongest inhibitor of α-glucosidase with an IC50 of 167.83 ± 23.82 μg/mL. Testing for the antiglycation potential of the extracts, measured as inhibition of formation of protein-bound fluorescent AGEs, showed that P. banksii root and fruit extracts had IC50 values of 34.49 ± 4.31 μg/mL and 47.72 ± 1.65 μg/mL, respectively, which were significantly lower (p < 0.05) than other extracts. The inhibitory effect on α-amylase, α-glucosidase and the antiglycation potential of the

  19. Operation and thermal loading of three-level Neutral-Point-Clamped wind power converter under various grid faults

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede; Liserre, Marco

    2012-01-01

    Ride Through (LVRT) operation under grid faults, may compromise the reliability of the system and consequently further increase its cost. In this paper, the impact of various grid faults on a three-level Neutral-Point-Clamped (3L-NPC) grid-converter in terms of thermal loading of power semiconductor...... devices is highlighted. It has been found that the thermal loading of the phases of the power converter may be uneven and dependent on the different types and severities of grid voltage dips as well as on the chosen control algorithms.......In order to fulfill the continuous growing grid-side demands, the full-scale power converters are becoming more and more popular in the wind power application. Nevertheless, the more severe loading of the power semiconductor devices in the full-scale power converters, especially during Low Voltage...

  20. Angiotensin I-Converting Enzyme (ACE Inhibitory Activity and ACE Inhibitory Peptides of Salmon (Salmo salar Protein Hydrolysates Obtained by Human and Porcine Gastrointestinal Enzymes

    Directory of Open Access Journals (Sweden)

    Małgorzata Darewicz

    2014-08-01

    Full Text Available The objectives of the present study were two-fold: first, to detect whether salmon protein fractions possess angiotensin I-converting enzyme (ACE inhibitory properties and whether salmon proteins can release ACE inhibitory peptides during a sequential in vitro hydrolysis (with commercial porcine enzymes and ex vivo digestion (with human gastrointestinal enzymes. Secondly, to evaluate the ACE inhibitory activity of generated hydrolysates. A two-step ex vivo and in vitro model digestion was performed to simulate the human digestion process. Salmon proteins were degraded more efficiently by porcine enzymes than by human gastrointestinal juices and sarcoplasmic proteins were digested/hydrolyzed more easily than myofibrillar proteins. The ex vivo digested myofibrillar and sarcoplasmic duodenal samples showed IC50 values (concentration required to decrease the ACE activity by 50% of 1.06 and 2.16 mg/mL, respectively. The in vitro hydrolyzed myofibrillar and sarcoplasmic samples showed IC50 values of 0.91 and 1.04 mg/mL, respectively. Based on the results of in silico studies, it was possible to identify 9 peptides of the ex vivo hydrolysates and 7 peptides of the in vitro hydrolysates of salmon proteins of 11 selected peptides. In both types of salmon hydrolysates, ACE-inhibitory peptides IW, IY, TVY and VW were identified. In the in vitro salmon protein hydrolysates an ACE-inhibitory peptides VPW and VY were also detected, while ACE-inhibitory peptides ALPHA, IVY and IWHHT were identified in the hydrolysates generated with ex vivo digestion. In our studies, we documented ACE inhibitory in vitro effects of salmon protein hydrolysates obtained by human and as well as porcine gastrointestinal enzymes.

  1. Measuring angiotensin-I converting enzyme inhibitory activity by micro plate assays: comparison using marine cryptides and tentative threshold determinations with captopril and losartan.

    Science.gov (United States)

    Ben Henda, Yesmine; Labidi, Anis; Arnaudin, Ingrid; Bridiau, Nicolas; Delatouche, Régis; Maugard, Thierry; Piot, Jean-Marie; Sannier, Frédéric; Thiéry, Valérie; Bordenave-Juchereau, Stéphanie

    2013-11-13

    To determine the angiotensin-I converting enzyme (ACE) inhibitory activity of marine cryptides, different methods were tested. ACE inhibition was measured using two synthetic substrates, (N-[3-(2-furyl) acryloyl]-Phe-Gly-Gly (FAPGG) and N-hippuryl-His-Leu hydrate salt (HHL)), and a natural one, angiotensin-I. The IC50 value (defined as the concentration of inhibitory molecule needed to inhibit 50% of the ACE activity) of the reference synthetic inhibitor captopril was in the nanomolar range (1.79-15.1 nM) when synthetic substrates were used, whereas it exhibited IC50 of micromolar range (16.71 μM) with angiotensin-I. We chose losartan, an antagonist of angiotensin-II receptor as negative control for the ACE inhibition. Losartan was also able to inhibit ACE whatever the substrate tested, with IC50 of micromolar range (17.13-146 μM). We defined this value as a limit above which molecules are not showing in vitro ACE inhibitory activity. Val-Trp (VW), Val-Tyr (VY), Lys-Tyr (KY), Lys-Trp (KW), Ile-Tyr (IY), Ala-Pro (AP), Val-Ile-Tyr (VIY), Leu-Lys-Pro (LKP), Gly-Pro-Leu (GPL), Ala-Lys-Lys (AKK), and Val-Ala-Pro (VAP) were tested as inhibitors of ACE with synthetic and natural substrates. IC50 displayed were substrate-dependent. With FAPGG as substrate, IW, VAP, KY, IY, AP, AKK, and VIY show IC50 values over the IC50 value of losartan and should not be considered as inhibitors of ACE. VY, VW, KW, and LKP exhibited IC50 value lower than the IC50 value of losartan for all substrates tested and were thus considered as good candidates for effectively decreasing hypertension. It appears that the comparison of IC50 is not consistent when IC50 values are obtained with different substrates and different methods. In vitro ACE inhibitory activity assays should always include various ACE substrates and references such as captopril and a negative control to obtain data reliable to discriminate ACE inhibitory peptides.

  2. Efficiency of Capacitively Loaded Converters

    DEFF Research Database (Denmark)

    Andersen, Thomas; Huang, Lina; Andersen, Michael A. E.

    2012-01-01

    This paper explores the characteristic of capacitance versus voltage for dielectric electro active polymer (DEAP) actuator, 2kV polypropylene film capacitor as well as 3kV X7R multi layer ceramic capacitor (MLCC) at the beginning. An energy efficiency for capacitively loaded converters...... is introduced as a definition of efficiency. The calculated and measured efficiency curves for charging DEAP actuator, polypropylene film capacitor and X7R MLCC are provided and compared. The attention has to be paid for the voltage dependent capacitive load, like X7R MLCC, when evaluating the charging...... efficiency of converter. Based on the capacitancevoltage curve, the correct capacitance should be chosen when calculating the stored energy; otherwise misleading optimistic efficiency can always be obtained. Actually, when DEAP actuator is not available at the early developing stage, the voltage independent...

  3. SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Vicinanza, Diego; Frigaard, Peter

    2008-01-01

    The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level, in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low...... head hydroturbines are converting the potential energy of the stored water into power. A key to success for the SSG will be the low cost of the structure and its robustness. The construction of the pilot plant is scheduled and this paper aims to describe the concept of the SSG wave energy converter...... and the studies behind the process that leads to its construction. The pilot plant is an on-shore full scale module in 3 levels with an expected power production of 320 MWh/y in the North Sea. Location, wave climate and laboratory tests results will be used here to describe the pilot plant and its characteristics....

  4. Angiotensin I-converting enzyme (ACE) inhibitory activity of Fucus spiralis macroalgae and influence of the extracts storage temperature-A short report.

    Science.gov (United States)

    Paiva, Lisete; Lima, Elisabete; Neto, Ana Isabel; Baptista, José

    2016-11-30

    Recently, increasing attention has been paid to the marine algae as a natural source of novel angiotensin-I converting enzyme (ACE) inhibitors, such as the phlorotannins that are the predominant polyphenols in brown algae. This study reports, for the first time, the ACE inhibition of methanol extract/fractions from Azorean brown algae Fucus spiralis (Fs) determined by HPLC-UV method, their total phenolic content (TPC) quantified as phloroglucinol equivalents (PE) and the effect of the Fs dry powder methanol extracts (Fs-DME) storage temperature on ACE inhibition. The results indicate that the ACE inhibition of Fs-DME decreased by 28.8% and 78.2% when stored during 15days at -80°C and -13°C, respectively, as compared with the activity of Fs-DME at a refrigerated temperature of 6°C and assayed immediately after extraction that showed a value of 80.1±2.1%. This Fs-DME sample was fractionated by ultrafiltration membranes into three molecular weight ranges (3kDa), presenting the fraction>3kDa remarkably high ACE inhibition (88.8±2.4%), TPC value (156.6±1.4mg PE/g of dry weight fraction) and yield. Furthermore, chromatographic and spectrophotometric analyses corroborate that phenolic compounds were present in Fs methanol extract/fractions, and also revealed that phloroglucinol occurs in Fs. The results seem to suggest that Azorean Fs can be a source of powerful ACE-inhibitory phlorotannins with potential impact on public health, particularly on hypertensive patients. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Mitogen-activated protein kinase kinase 1/2 inhibition and angiotensin II converting inhibition in mice with cardiomyopathy caused by lamin A/C gene mutation

    Energy Technology Data Exchange (ETDEWEB)

    Muchir, Antoine, E-mail: a.muchir@institut-myologie.org [Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY (United States); Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY (United States); Wu, Wei [Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY (United States); Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY (United States); Sera, Fusako; Homma, Shunichi [Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY (United States); Worman, Howard J., E-mail: hjw14@columbia.edu [Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY (United States); Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY (United States)

    2014-10-03

    Highlights: • Both ACE and MEK1/2 inhibition are beneficial on cardiac function in Lmna cardiomyopathy. • MEK1/2 inhibitor has beneficial effects beyond ACE inhibition for Lmna cardiomyopathy. • These results provide further preclinical rationale for a clinical trial of a MEK1/2 inhibitor. - Abstract: Background: Mutations in the LMNA gene encoding A-type nuclear lamins can cause dilated cardiomyopathy with or without skeletal muscular dystrophy. Previous studies have shown abnormally increased extracellular signal-regulated kinase 1/2 activity in hearts of Lmna{sup H222P/H222P} mice, a small animal model. Inhibition of this abnormal signaling activity with a mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor has beneficial effects on heart function and survival in these mice. However, such treatment has not been examined relative to any standard of care intervention for dilated cardiomyopathy or heart failure. We therefore examined the effects of an angiotensin II converting enzyme (ACE) inhibitor on left ventricular function in Lmna{sup H222P/H222P} mice and assessed if adding a MEK1/2 inhibitor would provide added benefit. Methods: Male Lmna{sup H222P/H222P} mice were treated with the ACE inhibitor benazepril, the MEK1/2 inhibitor selumetinib or both. Transthoracic echocardiography was used to measure left ventricular diameters and fractional shortening was calculated. Results: Treatment of Lmna{sup H222P/H222P} mice with either benazepril or selumetinib started at 8 weeks of age, before the onset of detectable left ventricular dysfunction, lead to statistically significantly increased fractional shortening compared to placebo at 16 weeks of age. There was a trend towards a great value for fractional shortening in the selumetinib-treated mice. When treatment was started at 16 weeks of age, after the onset of left ventricular dysfunction, the addition of selumetinib treatment to benazepril lead to a statistically significant increase in left

  6. Effects of gamma irradiation on microbiological, phytochemical content, antioxidant activity and inhibition of angiotensin converting enzyme (ACE) Activity of Peperomia pellucida (L.) Kunth

    NARCIS (Netherlands)

    Mun'im, Abdul; Ramadhani, Fitria; Chaerani, Kartika; Amelia, Lili; Arrahman, Arif

    2017-01-01

    Objective: Gamma irradiation is an effective technique can be used to reduce contaminants in herbal products. Peperomia pellucida (L.) Kunth belongs to Piperaceae family has some biological activity, such as antioxidant and ACE inhibitor. The aimed of this research was to determine the effects of

  7. Microwave pyrolysis using self-generated pyrolysis gas as activating agent: An innovative single-step approach to convert waste palm shell into activated carbon

    Science.gov (United States)

    Yek, Peter Nai Yuh; Keey Liew, Rock; Shahril Osman, Mohammad; Chung Wong, Chee; Lam, Su Shiung

    2017-11-01

    Waste palm shell (WPS) is a biomass residue largely available from palm oil industries. An innovative microwave pyrolysis method was developed to produce biochar from WPS while the pyrolysis gas generated as another product is simultaneously used as activating agent to transform the biochar into waste palm shell activated carbon (WPSAC), thus allowing carbonization and activation to be performed simultaneously in a single-step approach. The pyrolysis method was investigated over a range of process temperature and feedstock amount with emphasis on the yield and composition of the WPSAC obtained. The WPSAC was tested as dye adsorbent in removing methylene blue. This pyrolysis approach provided a fast heating rate (37.5°/min) and short process time (20 min) in transforming WPS into WPSAC, recording a product yield of 40 wt%. The WPSAC was detected with high BET surface area (≥ 1200 m2/g), low ash content (< 5 wt%), and high pore volume (≥ 0.54 cm3/g), thus recording high adsorption efficiency of 440 mg of dye/g. The desirable process features (fast heating rate, short process time) and the recovery of WPSAC suggest the exceptional promise of the single-step microwave pyrolysis approach to produce high-grade WPSAC from WPS.

  8. Angiotensin-converting enzyme

    DEFF Research Database (Denmark)

    Sørensen, P G; Rømer, F K; Cortes, D

    1984-01-01

    In order to evaluate bleomycin-associated lung damage in humans, lung function parameters and serum levels of the endothelial-bound angiotensin-converting enzyme (ACE) were determined by serial measurements in 11 patients who were treated for testicular cancer. None developed clinical or radiolog...

  9. Thermionic energy converters

    Science.gov (United States)

    Monroe, Jr., James E.

    1977-08-09

    A thermionic device for converting nuclear energy into electrical energy comprising a tubular anode spaced from and surrounding a cylindrical cathode, the cathode having an outer emitting surface of ruthenium, and nuclear fuel on the inner cylindrical surface. The nuclear fuel is a ceramic composition of fissionable material in a metal matrix. An axial void is provided to collect and contain fission product gases.

  10. Definition of Power Converters

    CERN Document Server

    Bordry, F

    2015-01-01

    The paper is intended to introduce power conversion principles and to define common terms in the domain. The concept s of sources and switches are defined and classified. From the basic laws of source interconnections, a generic method of power converter synthesis is presented. Some examples illustrate this systematic method. Finally, the commutation cell and soft commuta tion are introduced and discussedd.

  11. An Electromagnetic Beam Converter

    DEFF Research Database (Denmark)

    2009-01-01

    The present invention relates to an electromagnetic beam converter and a method for conversion of an input beam of electromagnetic radiation having a bell shaped intensity profile a(x,y) into an output beam having a prescribed target intensity profile l(x',y') based on a further development...

  12. Comparison of Performance and Realization Effort of a Very Sparse Matrix Converter to a Voltage DC Link PWM Inverter with Active Front End

    Science.gov (United States)

    Round, Simon; Schafmeister, Frank; Heldwein, Marcelo; Pereira, Eduardo; Serpa, Leonardo; Kolar, Johann

    This paper undertakes a comparison of the very sparse matrix converter (VSMC) and the back-to-back voltage DC-link converter (BBC) for a permanent magnetic synchronous motor drive application. The VSMC has the same functionality as the conventional matrix converter but a reduced number of switches and lower control complexity. The two converters are designed, using the same IGBT power modules, with a switching frequency of 40kHz and a thermal rating of 6.8kW at an ambient temperature of 45°C. From the design, the volume of the VSMC is 2.3 liters and is half that of the BBC. The efficiency for the VSMC at full load is 94.5% compared to 92% for the BBC. At very low output frequencies the output current of the VSMC can be increased by 25% above nominal compared to a 54% decrease for the BBC. Overall the VSMC offers advantages in volume and efficiency for motor drive applications requiring switching frequencies above 10kHz.

  13. Met-Lys-bradykinin-Ser-Ser, a peptide produced by the neutrophil from kininogen, is metabolically activated by angiotensin converting enzyme in vascular tissue.

    Science.gov (United States)

    Gera, Lajos; Roy, Caroline; Bawolak, Marie-Thérèse; Bouthillier, Johanne; Adam, Albert; Marceau, François

    2011-11-01

    Bradykinin (BK) is a vasoactive nonapeptide cleaved from circulating kininogens and that is degraded by angiotensin converting enzyme (ACE). It has been reported that the PR3 protease from human neutrophil releases an alternate peptide of 13 amino acids, Met-Lys-BK-Ser-Ser, from high molecular weight kininogen. We have studied vascular actions of this kinin. Its affinity for recombinant B₁ and B₂ receptors is very low, as assessed by the binding competition of [³H]Lys-des-Arg⁹-BK and [³H]BK, respectively, but Met-Lys-BK-Ser-Ser effectively displaced a fraction of [³H]enalaprilat binding to recombinant ACE. Mutant recombinant ACE constructions revealed that affinity gap between BK and Met-Lys-BK-Ser-Ser is larger for the N-terminal catalytic site than for the C-terminal one, based on competition for the substrate Abz-Phe-Arg-Lys(Dnp)-Pro-OH in an enzymatic assay. Met-Lys-BK-Ser-Ser is a low potency stimulant of the rabbit aorta (bioassay for B₁ receptors), but the human isolated umbilical vein, a contractile bioassay for the B₂ receptors, responded to Met-Lys-BK-Ser-Ser more than expected from the radioligand binding assay, this agonist being ∼30-fold less potent than BK in the vein. Venous tissue treatment with the ACE inhibitor enalaprilat reduced the apparent potency of Met-Lys-BK-Ser-Ser by 15-fold, while not affecting that of BK. In the rabbit isolated jugular vein, Met-Lys-BK-Ser-Ser is nearly as potent as BK as a contractile stimulant of endogenous B₂ receptors (EC₅₀ values of 16.3 and 10.5 nM, respectively), but enalaprilat reduced the potency of Met-Lys-BK-Ser-Ser 13-fold while increasing that of BK 5.3-fold. In vascular tissue, ACE assumes a paradoxical activating role for Met-Lys-BK-Ser-Ser. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Design of Neutral-Point Voltage Controller of a Three-level NPC Inverter with Small DC-Link Capacitors

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, S.

    2013-01-01

    A Neutral-Point-Clamped (NPC) three-level inverter with small dc-link capacitors is presented in this paper. The inverter requires zero average neutral-point current for stable neutral-point voltage. The small dc-link capacitors may not maintain capacitor voltage balance, even with zero neutral-point...... current. This may happen due to nonlinearities present in the circuit. This requires a fast control of the neutral-point voltage. A simple carrier based modulation strategy which allows modeling of the neutral-point voltage dynamics as a continuous function of power drawn from the inverter is proposed....... This continuous model shows that the neutral-point current is proportional to the power drawn from the inverter, and it enables the use of well established classical control theory for the neutral-point voltage controller design. A simple PI (proportional integral) controller is designed for the neutral-point...

  15. Filter optimization of Si and SiC semiconductor-based H5 and Conergy-NPC transformerless PV inverters

    DEFF Research Database (Denmark)

    Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede

    2013-01-01

    semiconductors type (Si- or SiC-based), switching frequency and output filter (LCL- or LLCL-type) employed in H5 and Conergy-NPC PV inverters, considering the simultaneous impact of the factors affecting the PV energy processing performance and PV inverter cost. According to the design results, the optimized Si......C-based PV inverters will inject more energy into the electric grid, compared to the Si-based structures and enable the reduction of the output filter size, weight and cost. Employing an LLCL-type output filter and simultaneously reducing the cost of SiC power semiconductors to the level of their Si......Single-phase transformerless Photovoltaic (PV) inverters are synthesized by combining available solutions in terms of the power section topology, power semiconductors manufacturing technology and structure of the output filter. A design method is presented in this paper for optimizing the power...

  16. Thermal Equilibrium Dynamic Control Based on DPWM Dual-Mode Modulation of High Power NPC Three-Level Inverter

    Directory of Open Access Journals (Sweden)

    Shi-Zhou Xu

    2016-01-01

    Full Text Available In some special applications of NPC three-level inverters, such as mine hoist, there exist special conditions of overloading during the whole hoisting process and large overload in starting stage, during which the power-loss calculation of power devices and thermal control are important factors affecting the thermal stability of inverters. The principles of SVPWM and DPWM were described in this paper firstly, based on which the dynamic power losses of the two modulations of hoist in single period were calculated. Secondly, a thermal equilibrium dynamic control based on DPMW dual-mode modulation was proposed, which can switch the modulation dynamically according to the change of dynamic power loss to realize dynamic control of power loss and thermal equilibrium of inverter. Finally, simulation and experiment prove the effectiveness of the proposed strategy.

  17. The microminiature thermionic converter

    Science.gov (United States)

    King, Donald B.; Luke, James R.; Zavadil, Kevin R.

    2001-02-01

    A new generation of thermionic converter, the microminiature thermionic converter (MTC) has been fabrication using semiconductor integrated circuit (IC) fabrication methods and micromachining manufacturing (MM) techniques. The use of IC and MM techniques allows the fabrication of MTCs with micron scale cathode to anode spacing and with anode and cathode materials which will have work functions ranging from 1 eV to 2.5 eV. The use of small cathode to anode spacing and variable electrode work functions gives the MTC the potential to convert heat energy to relatively large current densities (up to 10s of Amps/cm2) at relatively high conversion efficiencies (~25%), well within the range of high end conventional electrical generation equipment. Tests of prototype MTCs have demonstrated energy conversion at several emitter and collector temperatures. Power generated by the prototype MTC is less than expected because of less than optimal emission characteristics encountered with the low work function materials used for the first MTC prototypes. Work is in progress to improve the thermionic emission characteristics of the low work function electrodes. .

  18. Multilevel converters -- A new breed of power converters

    Energy Technology Data Exchange (ETDEWEB)

    Lai, J.S. [Oak Ridge National Lab., TN (United States). Engineering Technology Div.; Peng, F.Z. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States)

    1995-09-01

    Multilevel voltage source converters are emerging as a new breed of power converter options for high-power applications. The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc capacitor voltages. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. The techniques to balance the voltage between different levels normally involve voltage clamping or capacitor charge control. There are several ways of implementing voltage balance in multilevel converters. Without considering the traditional magnetic coupled converters, this paper presents three recently developed multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded-inverters with separate dc sources. The operating principle, features, constraints, and potential applications of these converters will be discussed.

  19. A generalized discontinuous PWM based neutral point voltage balancing method for three-level NPC voltage source inverter with switching losses reduction

    DEFF Research Database (Denmark)

    Li, Kai; Wei, Min; Xie, Chuan

    2017-01-01

    In order to control the neutral point voltage of inverter with discontinuous PWM (DPWM), this paper proposed a generalized discontinuous PWM (GDPWM) based neutral point voltage balancing method for three level neutral point clamped (NPC) voltage source inverter (VSI). Firstly, a triangle carrier ...

  20. Oxygen reduction in an acid medium - electrocatalysis by CoNPc (1,2) impregnated on a carbon black support - effect of loading and heat treatment

    NARCIS (Netherlands)

    Biloul, A.; Coowar, F.; Contamin, O.; Scarbeck, G.; Savy, M.; van den Ham, D.; van den Ham, D.M.W.; Riga, J.; Verbist, J.J.

    1993-01-01

    O2 reduction in an acid medium has been investigated on a transition metal macrocycle, CoNPc(1,2), impregnated on a carbon black support with a high dibutylphthalate adsorption value, using a rotating disk electrode and voltammetry techniques described previously, combined with X-ray photoelectron

  1. X-Y Converter Family

    DEFF Research Database (Denmark)

    Bhaskar, Mahajan Sagar; Sanjeevikumar, Padmanaban; Wheeler, Patrick

    2016-01-01

    A New breed of a buck boost converter, named as the XY converter family is proposed in this article. In the XY family, 16 topologies are presented which are highly suitable for renewable energy applications which require a high ratio of DC-DC converter; such as a photovoltaic multilevel inverter...... system, high voltage automotive applications and industrial drives. Compared to the traditional boost converter and existing recent converters, the proposed XY converter family has the ability to provide a higher output voltage by using less number of power devices and reactive components. Other distinct...... features of the XY converter family are i) Single control switch ii) Provide negative output voltage iii) Non-isolated topologies iv) High conversion ratio without making the use of high duty cycle and v) modular structure. XY family is compared with the recent high step-up converters and the detailed...

  2. Cycloidal Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  3. Resonant power converters

    CERN Document Server

    Kazimierczuk, Marian K

    2012-01-01

    This book is devoted to resonant energy conversion in power electronics. It is a practical, systematic guide to the analysis and design of various dc-dc resonant inverters, high-frequency rectifiers, and dc-dc resonant converters that are building blocks of many of today's high-frequency energy processors. Designed to function as both a superior senior-to-graduate level textbook for electrical engineering courses and a valuable professional reference for practicing engineers, it provides students and engineers with a solid grasp of existing high-frequency technology, while acquainting them wit

  4. Bidirectional DC/DC Converter

    Science.gov (United States)

    Pedersen, F.

    2008-09-01

    The presented bidirectional DC/DC converter design concept is a further development of an already existing converter used for low battery voltage operation.For low battery voltage operation a high efficient low parts count DC/DC converter was developed, and used in a satellite for the battery charge and battery discharge function.The converter consists in a bidirectional, non regulating DC/DC converter connected to a discharge regulating Buck converter and a charge regulating Buck converter.The Bidirectional non regulating DC/DC converter performs with relatively high efficiency even at relatively high currents, which here means up to 35Amps.This performance was obtained through the use of power MOSFET's with on- resistances of only a few mille Ohms connected to a special transformer allowing paralleling several transistor stages on the low voltage side of the transformer. The design is patent protected. Synchronous rectification leads to high efficiency at the low battery voltages considered, which was in the range 2,7- 4,3 Volt DC.The converter performs with low switching losses as zero voltage zero current switching is implemented in all switching positions of the converter.Now, the drive power needed, to switch a relatively large number of low Ohm , hence high drive capacitance, power MOSFET's using conventional drive techniques would limit the overall conversion efficiency.Therefore a resonant drive consuming considerable less power than a conventional drive circuit was implemented in the converter.To the originally built and patent protected bidirectional non regulating DC/DC converter, is added the functionality of regulation.Hereby the need for additional converter stages in form of a Charge Buck regulator and a Discharge Buck regulator is eliminated.The bidirectional DC/DC converter can be used in connection with batteries, motors, etc, where the bidirectional feature, simple design and high performance may be useful.

  5. Fluorescent radiation converter

    Science.gov (United States)

    Viehmann, W. (Inventor)

    1981-01-01

    A fluorescence radiation converter is described which includes a substantially undoped optically transparent substrate and a waveshifter coating deposited on at least one portion of the substrate for absorption of radiation and conversion of fluorescent radiation. The coating is formed to substantially 1000 g/liter of a solvent, 70 to 200 g/liter of an organic polymer, and 0.2 to 25 g/liter of at least one organic fluorescent dye. The incoming incident radiation impinges on the coating. Radiation is absorbed by the fluorescent dye and is re-emitted as a longer wavelength radiation. Radiation is trapped within the substrate and is totally internally reflected by the boundary surface. Emitted radiation leaves the substrate ends to be detected.

  6. Electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  7. Integrated power electronic converters and digital control

    CERN Document Server

    Emadi, Ali; Nie, Zhong

    2009-01-01

    Non-isolated DC-DC ConvertersBuck ConverterBoost ConverterBuck-Boost ConverterIsolated DC-DC ConvertersFlyback ConverterForward ConverterPush-Pull ConverterFull-Bridge ConverterHalf-Bridge ConverterPower Factor CorrectionConcept of PFCGeneral Classification of PFC CircuitsHigh Switching Frequency Topologies for PFCApplication of PFC in Advanced Motor DrivesIntegrated Switched-Mode Power ConvertersSwitched-Mode Power SuppliesThe Concept of Integrated ConverterDefinition of Integrated Switched-Mode Power Supplies (ISMPS)Boost-Type Integrated TopologiesGeneral Structure of Boost-Type Integrated T

  8. Advanced power electronics converters PWM converters processing AC voltages

    CERN Document Server

    dos Santos, Euzeli

    2014-01-01

    This book covers power electronics, in depth, by presenting the basic principles and application details, which can be used both as a textbook and reference book.  Introduces a new method to present power electronics converters called Power Blocks Geometry. Applicable for courses focusing on power electronics, power electronics converters, and advanced power converters. Offers a comprehensive set of simulation results to help understand the circuits presented throughout the book

  9. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  10. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    control methods. Presents the latest power conversion solutions that aim to advance the role of power electronics into industries and sustainable energy conversion systems. Compares impedance source converter/inverter applications in renewable energy power generation and electric vehicles as well......Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...

  11. Tetrandrine Induces Apoptosis in Human Nasopharyngeal Carcinoma NPC-TW 039 Cells by Endoplasmic Reticulum Stress and Ca2+/Calpain Pathways.

    Science.gov (United States)

    Liu, Kuo-Ching; Lin, Ya-Jing; Hsiao, Yung-Ting; Lin, Meng-Liang; Yang, Jiun-Long; Huang, Yi-Ping; Chu, Yung-Lin; Chung, Jing-Gung

    2017-11-01

    Tetrandrine is an alkaloid extracted from a traditional China medicine plant, and is considered part of food therapy as well. In addition, it has been widely reported to induce apoptotic cell death in many human cancer cells. However, the mechanism of Tetrandrine on human nasopharyngeal carcinoma cells (NPC) is still questioned. In our study, we examined whether Tetrandrine can induce apoptosis of NPC-TW 039 cells. We found that cell morphology was changed after treatment with different concentrations of Tetrandrine. Further, we indicated that the NPC-TW 039 cells viability decreased in a Tetrandrine dose-dependent manner. We also found that tetrandrine induced cell cycle arrest in G0/G1 phase. Tetrandrine induced DNA condensation by DAPI staining as well. In addition, we found that Tetrandrine induced Ca2+ release in the cytosol. At the same time, endoplasmic reticulum (ER) stress occurred. Then we used western blotting to examine the protein expression which is associated with mitochondria-mediated apoptotic pathways and caspase-dependent pathways. To further examine whether Ca2+ was released or not with Tetrandrine induced-apoptosis, we used the chelator of Ca2+ and showed that cell viability increased. At the same time, caspase-3 expression was decreased. Furthermore, confocal microscopy examination revealed that Tetrandrine induced expression of ER stress-related proteins GADD153 and GRP78. Our results indicate that Tetrandrine induces apoptosis through calcium-mediated ER stress and caspase pathway in NPC-TW 039 cells. In conclusion, Tetrandrine may could be used for treatment of human nasopharyngeal carcinoma in future. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  12. Data Converter for Multistandard Mobile Phones

    DEFF Research Database (Denmark)

    Yurttas, Aziz; Bruun, Erik; Jensen, Rasmus Glarborg

    2004-01-01

    This paper describes an analog to digital converter (ADC) for mobile communication systems using a direct down conversion architecture. The ADC can be programmed to meet the requirements of different communication standards, including GSM (Global System for Mobile communication) and WCDMA (Wideband...... Code Division Multiple Access). The ADC is realized with a pipeline ADC architecture for WCDMA and a Sigma-Delta architecture for GSM. In order to have an optimized area and power consumption, the basic building blocks (opamps) of the converters are shared between the two converter architectures....... The entire ADC consumes about 5.5 mW and occupies an active area of about 0.36 mm(2). A test circuit has been developed and fabricated and measurements show that both the required programmability and the required performance can be obtained using the proposed configurations....

  13. Parametric pendulum based wave energy converter

    Science.gov (United States)

    Yurchenko, Daniil; Alevras, Panagiotis

    2018-01-01

    The paper investigates the dynamics of a novel wave energy converter based on the parametrically excited pendulum. The herein developed concept of the parametric pendulum allows reducing the influence of the gravity force thereby significantly improving the device performance at a regular sea state, which could not be achieved in the earlier proposed original point-absorber design. The suggested design of a wave energy converter achieves a dominant rotational motion without any additional mechanisms, like a gearbox, or any active control involvement. Presented numerical results of deterministic and stochastic modeling clearly reflect the advantage of the proposed design. A set of experimental results confirms the numerical findings and validates the new design of a parametric pendulum based wave energy converter. Power harvesting potential of the novel device is also presented.

  14. Development and validation of a new tool measuring nurses self-reported professional competence--the nurse professional competence (NPC) Scale.

    Science.gov (United States)

    Nilsson, Jan; Johansson, Eva; Egmar, Ann-Charlotte; Florin, Jan; Leksell, Janeth; Lepp, Margret; Lindholm, Christina; Nordström, Gun; Theander, Kersti; Wilde-Larsson, Bodil; Carlsson, Marianne; Gardulf, Ann

    2014-04-01

    To develop and validate a new tool intended for measuring self-reported professional competence among both nurse students prior to graduation and among practicing nurses. The new tool is based on formal competence requirements from the Swedish Board of Health and Welfare, which in turn are based on WHO guidelines. A methodological study including construction of a new scale and evaluation of its psychometric properties. 1086 newly graduated nurse students from 11 universities/university colleges. The analyses resulted in a scale named the NPC (Nurse Professional Competence) Scale, consisting of 88 items and covering eight factors: "Nursing care", "Value-based nursing care", "Medical/technical care", "Teaching/learning and support", "Documentation and information technology", "Legislation in nursing and safety planning", "Leadership in and development of nursing care" and "Education and supervision of staff/students". All factors achieved Cronbach's alpha values greater than 0.70. A second-order exploratory analysis resulted in two main themes: "Patient-related nursing" and "Nursing care organisation and development". In addition, evidence of known-group validity for the NPC Scale was obtained. The NPC Scale, which is based on national and international professional competence requirements for nurses, was comprehensively tested and showed satisfactory psychometrical properties. It can e.g. be used to evaluate the outcomes of nursing education programmes, to assess nurses' professional competences in relation to the needs in healthcare organisations, and to tailor introduction programmes for newly employed nurses. © 2013.

  15. A Bovine Fibrinogen-Enriched Fraction as a Source of Peptides with in Vitro Renin and Angiotensin-I-Converting Enzyme Inhibitory Activities.

    Science.gov (United States)

    Lafarga, Tomas; Rai, Dilip K; O'Connor, Paula; Hayes, Maria

    2015-10-07

    Bovine fibrinogen is currently used in the food industry as a binding agent in restructured meat products. However, this protein is underused as a source of bioactive peptides. In this study, a number of novel angiotensin-I-converting enzyme (ACE-I) and renin inhibitory peptides were identified and enriched from a bovine fibrinogen fraction. Fibrinogen was isolated and enriched from bovine blood and hydrolyzed with the food-grade enzyme papain, which was selected for use using in silico analysis. The generated hydrolysate was subjected to ultrafiltration and its peptide profile characterized by liquid chromatography-tandem mass spectrometry. A number of peptides were identified and chemically synthesized to confirm their bioactivity in vitro. Identified peptides included the multifunctional tripeptide SLR, corresponding to f(35-37) of the β-chain of bovine fibrinogen with ACE-I and renin IC50 values of 0.17 and 7.2 mM, respectively. Moreover, the resistance of identified peptides to gastrointestinal degradation and their bitterness were predicted using in silico methods.

  16. ZVZCS PWM DC-DC Converter with Energy Recovery Clamp

    Directory of Open Access Journals (Sweden)

    Jaroslav Durdik

    2008-01-01

    Full Text Available This paper presents research motivated by industrial demand for special traction drive topology devoted tominimization of traction transformer weight against topology with classical 50Hz traction transformer. The special tractiondrive topology for AC power systems consists of input high voltage trolley converter (single phase matrix converter –middle frequency transformer – output converter - traction motor has been described. The main attention has been given tothe control algorithm of the traction topology (inserting of NULL vector of matrix converter and Two-value control ofsecondary active rectifier.

  17. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    control methods. Presents the latest power conversion solutions that aim to advance the role of power electronics into industries and sustainable energy conversion systems. Compares impedance source converter/inverter applications in renewable energy power generation and electric vehicles as well......Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...

  18. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key......Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... control methods. Presents the latest power conversion solutions that aim to advance the role of power electronics into industries and sustainable energy conversion systems. Compares impedance source converter/inverter applications in renewable energy power generation and electric vehicles as well...

  19. High Voltage Bi-directional Flyback Converter for Capacitive Actuator

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    This paper presents a high voltage DC-DC converter topology for bi-directional energy transfer between a low voltage DC source and a high voltage capacitive load. The topology is a bi-directional flyback converter with variable switching frequency control during the charge mode, and constant...... switching frequency control during the discharge mode. The converter is capable of charging the capacitive load from 24 V DC source to 2.5 kV, and discharges it to 0 V. The flyback converter has been analyzed in detail during both charge and discharge modes, by considering all the parasitic elements...... in the converter, including the most dominating parameters of the high voltage transformer viz., self-capacitance and leakage inductance. The specific capacitive load for this converter is a dielectric electro active polymer (DEAP) actuator, which can be used as an effective replacement for conventional actuators...

  20. Grid Converters for Stationary Battery Energy Storage Systems

    DEFF Research Database (Denmark)

    Trintis, Ionut

    to hours, rated at MW and MWh, battery energy storage systems are suitable and ecient solutions. Grid connection of the storage system can be done at dierent voltage levels, depending on the location and application scenario. For high power and energy ratings, increase in the battery and converter voltage...... was realized for a 100 kW active rectier to be used in a 6 kV battery energy storage test bench. In the second part, dierent solutions for power converters to interface energy storage units to medium voltage grid are given. A new modular multilevel converter concept is introduced, where the energy storage......-voltage 100 kW bidirectional grid converter, to be used in a high voltage battery energy storage test bench. The control structure proved to be stable without damping. The converter was tested in the test bench and the experimental results are presented. Multilevel converters are replacing the classical two...

  1. Comparative Toxicity of Three Inhibitors of The Converting Enzyme ...

    African Journals Online (AJOL)

    User

    2012-07-12

    Jul 12, 2012 ... Three angiotensin converting enzyme (ACE) inhibitors, enalapril, lisinopril and captopril were tested in vivo by topical ... Key words: Ephestia kuehniella, development, growth, ecdysteroids, angiotensin converting enzyme, captopril, enalapril ... High levels of ACE activity are found in the haemolymph and in ...

  2. Coping with Harmonics in Smart Grid: variable speed driveswith Back-to-Back Voltage Source Converter versus the matrix converter

    OpenAIRE

    Ali, Imran

    2013-01-01

    In this master thesis it has been investigated to utilize the matrix as a shunt active power filter and an adjustable speed drive and then compare the matrix converter with the Back-to-Back voltage source converter in terms of active filtering capability and reactive power compensation.In first steps to utilize the matrix converter as a motor drive and a shunt active power filter the control systems for the Permanent magnet synchronous machine, shunt active power filter and 3-phase LC-filter ...

  3. Converter topologies for common mode voltage reduction

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Fernando

    2017-11-21

    An inverter includes a three-winding transformer, a DC-AC inverter electrically coupled to the first winding of the transformer, a cycloconverter electrically coupled to the second winding of the transformer, and an active filter electrically coupled to the third winding of the transformer. The DC-AC inverter is adapted to convert the input DC waveform to an AC waveform delivered to the transformer at the first winding. The cycloconverter is adapted to convert an AC waveform received at the second winding of the transformer to the output AC waveform having a grid frequency of the AC grid. The active filter is adapted to sink and source power with one or more energy storage devices based on a mismatch in power between the DC source and the AC grid. At least two of the DC-AC inverter, the cycloconverter, or the active filter are electrically coupled via a common reference electrical interconnect.

  4. Radiation tolerant power converter controls

    CERN Document Server

    Todd, B; King, Q; Uznanski, S

    2012-01-01

    The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to signifi...

  5. New fault tolerant matrix converter

    Energy Technology Data Exchange (ETDEWEB)

    Ibarra, Edorta; Andreu, Jon; Kortabarria, Inigo; Ormaetxea, Enekoitz; Alegria, Inigo Martinez de; Martin, Jose Luis [Department of Electronics and Telecommunications, University of the Basque Country, Alameda de Urquijo s/n, E-48013 Bilbao (Spain); Ibanez, Pedro [TECNALIA, Energy Unit, Parque Tecnologico de Zamudio, E-48170 Bizkaia (Spain)

    2011-02-15

    The matrix converter (MC) presents a promising topology that will have to overcome certain barriers (protection systems, durability, the development of converters for real applications, etc.) in order to gain a foothold in the industry. In some applications, where continuous operation must be insured in the case of a system failure, improved reliability of the converter is of particular importance. In this sense, this article focuses on the study of a fault tolerant MC. The fault tolerance of a converter is characterized by its total or partial response in the case of a breakage of any of its components. Taking into consideration that virtually no work has been done on fault tolerant MCs, this paper describes the most important studies in this area. Moreover, a new method is proposed for detecting the breakage of MC semiconductors. Likewise, a new variation of SVM modulation with failure tolerance capacity is presented. This guarantees the continuous operation of the converter and the pseudo-optimum control of a PMSM. This paper also proposes a novel MC topology, which allows the flexible reconfiguration of this converter, when one or several of its semiconductors are damaged. In this way, the MC can continue operating at 100% of its performance without having to double its resources. In this way, it can be said that the solution described in this article represents a step forward towards the development of reliable matrix converters for real applications. (author)

  6. A Harmonic Resonance Suppression Strategy for a High-Speed Railway Traction Power Supply System with a SHE-PWM Four-Quadrant Converter Based on Active-Set Secondary Optimization

    Directory of Open Access Journals (Sweden)

    Runze Zhang

    2017-10-01

    Full Text Available Pulse width modulation (PWM technology is widely used in traction converters for high-speed railways. The harmonic distribution caused by PWM is quite extensive, and increases the possibility of grid–train coupling resonance in the traction power supply system (TPSS. This paper first analyzes the mechanism of resonance, when the characteristic harmonic frequency of a four-quadrant converter (4QC current that injects into the traction grid matches the resonant frequency of the traction grid, which may result in resonance in the system. To suppress resonance, this paper adopts specific harmonic elimination–pulse width modulation (SHE-PWM technology combined with a transient direct current control strategy to eliminate the harmonics in the resonant frequency, which may suppress the grid–train coupling resonance. Due to the fact that the SHE-PWM process with multiple switching angles contains complex transcendental equations, the initial value is difficult to provide, and is difficult to solve using ordinary iterative algorithms. In this paper, an active-set secondary optimization method is used to solve the equation. The algorithm has the benefits of low dependence on initial values, fast convergence and high solution accuracy. Finally, the feasibility of the resonant suppression algorithm is verified by means of Matlab simulation.

  7. Sodium restriction potentiates the renoprotective effects of combined vitamin D receptor activation and angiotensin-converting enzyme inhibition in established proteinuric nephropathy

    NARCIS (Netherlands)

    Mirkovic, Katarina; Frenay, Anne-Roos S; van den Born, Jacob; van Goor, Harry; Navis, Gerjan; de Borst, Martin H

    2015-01-01

    BACKGROUND: Renin-angiotensin-aldosterone system (RAAS) blockade provides renoprotective effects in chronic kidney disease (CKD); yet progressive renal function loss remains common. Dietary sodium restriction potentiates the renoprotective effects of RAAS blockade. Vitamin D receptor activator

  8. Multilevel converters for industrial applications

    CERN Document Server

    Gonzalez, Sergio Alberto

    2013-01-01

    Modern semiconductor devices have reached high current and voltage levels, and their power-handling limits can be extended if they are used in multilevel converter configurations. To create high-performance and reliable control designs, however, engineers need in-depth understanding of the characteristics and operation of these topologies. Multilevel Converters for Industrial Applications presents a thorough and comprehensive analysis of multilevel converters with a common DC voltage source. The book offers a novel perspective to help readers understand the principles of the operation of volta

  9. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... control methods. Presents the latest power conversion solutions that aim to advance the role of power electronics into industries and sustainable energy conversion systems. Compares impedance source converter/inverter applications in renewable energy power generation and electric vehicles as well...... as different industrial applications. Provides an overview of existing challenges, solutions and future trends. Supported by calculation examples, simulation models and results....

  10. A Traction Three-Phase to Single-Phase Cascade Converter Substation in an Advanced Traction Power Supply System

    Directory of Open Access Journals (Sweden)

    Xiaoqiong He

    2015-09-01

    Full Text Available The advanced traction power supply system (ATPSS is a new directional development for traction power supply systems, which can totally remove the neutral sections and effectively promote power quality. However, the existing converters suffer from small substation capacity. In this paper, a new configuration based on a three-level neutral point clamped (3L-NPC three-phase to single-phase cascade converter in a substation is proposed for ATPSS, which can be used to match the capacity of the converter for high voltage and large power applications. The control strategy of the proposed converter is analyzed in depth, and the phase disposition sinusoidal pulse width modulation (PD-SPWM with phase shift carrier SPWM (PSC-SPWM is employed in the inverters. Then, the inductance equalizing circuit is applied for the voltage balance on the DC-link. Besides, a LC filter circuit is designed to eliminate the double line-frequency ripple of DC voltage. Afterwards, a simulation model and an experimental prototype are developed, respectively. The simulation results show that the proposed converter in this paper can not only meet the requirements of voltage and capacity for the traction network, but also improve power quality. Finally, the experimental results verify the correctness and feasibility of the proposed control strategy.

  11. Potent arylsulfonamide inhibitors of tumor necrosis factor-alpha converting enzyme able to reduce activated leukocyte cell adhesion molecule shedding in cancer cell models.

    Science.gov (United States)

    Nuti, Elisa; Casalini, Francesca; Avramova, Stanislava I; Santamaria, Salvatore; Fabbi, Marina; Ferrini, Silvano; Marinelli, Luciana; La Pietra, Valeria; Limongelli, Vittorio; Novellino, Ettore; Cercignani, Giovanni; Orlandini, Elisabetta; Nencetti, Susanna; Rossello, Armando

    2010-03-25

    Activated leukocyte cell adhesion molecule (ALCAM) plays a relevant role in tumor biology and progression. Our previous studies showed that ALCAM is expressed at the surface of epithelial ovarian cancer (EOC) cells and is released in a soluble form by ADAM-17-mediated shedding. This process is relevant to EOC cell motility and invasiveness, which is reduced by nonspecific inhibitors of ADAM-17. For this reason, ADAM-17 may represent a new useful target in anticancer therapy. Herein, we report the synthesis and biological evaluation of new ADAM-17 inhibitors containing an arylsulfonamidic scaffold. Among the new potential inhibitors, two very promising compounds 17 and 18 were discovered, with a nanomolar activity for ADAM-17 isolated enzyme. These compounds proved to be also the most potent in inhibiting soluble ALCAM release in cancer cells, showing a nanomolar activity on A2774 and SKOV3 cell lines.

  12. Wind/water energy converter

    Science.gov (United States)

    Paulkovich, J.

    1979-01-01

    Device will convert wind, water, tidal or wave energy into electrical or mechanical energy. Is comprised of windmill-like paddles or blades synchronously geared to orient themselves to wind direction for optimum energy extraction.

  13. Time-to-digital converters

    CERN Document Server

    Henzler, Stephan

    2010-01-01

    This text covers the fundamentals of time-to-digital converters on analog and digital conversion principles. It includes a theoretical investigation into quantization, linearity, noise and variability, and it details a range of advanced TDC architectures.

  14. Analog-to-digital converter

    Science.gov (United States)

    Lewyn, L. L. (Inventor)

    1965-01-01

    An analog to digital converter circuit arrangement is reported that is suitable for use in ultra fast pulse height analysis. The circuit uses series connected tunnel diodes to quantize a voltage signal into discrete levels.

  15. Laser system with wavelength converter

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention relates to an apparatus comprising a diode laser (10) providing radiation in a first wavelength interval, a radiation conversion unit (12) having an input and an output, the radiation converter configured to receive the radiation in the first wavelength interval from the diode...... laser at the input, the radiation conversion unit configured to convert the radiation in the first wavelength interval to radiation in a second wavelength interval and the output configured to output the converted radiation, the second wavelength interval having one end point outside the first...... wavelength interval. Further, the invention relates to a method of optically pumping a target laser (14) in a laser system, the laser system comprising a laser source providing radiation at a first frequency, the laser source being optically connected to an input of a frequency converter, the frequency...

  16. Kinetics and molecular docking studies of the inhibitions of angiotensin converting enzyme and renin activities by hemp seed (Cannabis sativa L.) peptides.

    Science.gov (United States)

    Girgih, Abraham T; He, Rong; Aluko, Rotimi E

    2014-05-07

    Four novel peptide sequences (WVYY, WYT, SVYT, and IPAGV) identified from an enzymatic digest of hemp seed proteins were used for enzyme inhibition kinetics and molecular docking studies. Results showed that WVYY (IC50 = 0.027 mM) was a more potent (p protein, especially formation of higher numbers of hydrogen bonds with active site residues.

  17. Radiation tolerant power converter controls

    Science.gov (United States)

    Todd, B.; Dinius, A.; King, Q.; Uznanski, S.

    2012-11-01

    The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to significantly increased radiation induced effects in materials close to the accelerator, including the FGC. Recent radiation tests indicate that the current FGC would not be sufficiently reliable. A so-called FGClite is being designed to work reliably in the radiation environment in the post-LS1 era. This paper outlines the concepts of power converter controls for machines such as the LHC, introduces the risks related to radiation and a radiation tolerant project flow. The FGClite is then described, with its key concepts and challenges: aiming for high reliability in a radiation field.

  18. Boron nitride converted carbon fiber

    Science.gov (United States)

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  19. Effect of Allium sativum and fish collagen on the proteolytic and angiotensin-I converting enzyme-inhibitory activities in cheese and yogurt.

    Science.gov (United States)

    Shori, A B; Baba, A S; Keow, J N

    2012-12-15

    There is an increasing demand of functional foods in developed countries. Yogurt plays an important role in the management of blood pressure. Several bioactive peptides isolated from Allium sativum or fish collagen have shown antihypertensive activity. Thus, in the present study the effects of A. sativum and/or Fish Collagen (FC) on proteolysis and ACE inhibitory activity in yogurt (0, 7 and 14 day) and cheese (0, 14 and 28 day) were investigated. Proteolytic activities were the highest on day 7 of refrigerated storage in A. sativum-FC-yogurt (337.0 +/- 5.3 microg g(-1)) followed by FC-yogurt (275.3 +/- 2.0 microg g(-1)), A. sativum-yogurt (245.8 +/- 4.2 microg g(-1)) and plain-yogurt (40.4 +/- 1.2 microg g(-1)). On the other hand, proteolytic activities in cheese ripening were the highest (p sativum-cheeses (411.4 +/- 4.3 and 528.7 +/- 1.6 microg g(-1), respectively). However, the presence of FC increased the proteolysis to the highest level on day 28 of storage for FC- and A. sativum-FC cheeses (641.2 +/- 0.1 and 1128.4 +/- 4.5 microg g(-1), respectively). In addition, plain- and A. sativum-yogurts with or without FC showed maximal inhibition of ACE on day 7 of storage. Fresh plain- and A. sativum-cheeses showed ACE inhibition (72.3 +/- 7.8 and 50.4 +/- 1.6 % respectively), the presence of FC in both type of cheeses reduced the ACE inhibition to 62.9 +/- 0.8 and 44.5 +/- 5.0%, respectively. However, refrigerated storage increased ACE inhibition in cheeses (p sativum-yogurt or cheese enhanced the proteolytic activity. Thus, it has potential in the development of an effective dietary strategy for hypertension associated cardiovascular diseases.

  20. Current status of converter steelmaking

    Energy Technology Data Exchange (ETDEWEB)

    Oghbasialasie, H.; Holappa, L.

    1995-12-31

    This literature work is mainly focusing on the mechanisms of modern converter steelmaking and related with the evaluation of converter technology applied during the last decades and further to the future. The history of steelmaking has been briefly reviewed from bloomeries and early-steelmaking processes to the progress of modern converter process. The pneumatic converter processes were developed in the 1850`s and thereafter the basis for the rapid growth of steel industries was established for the next 100 years. The world production of steel has not continuously grown but fluctuating quite much. It reached 723 Mt in 1994. The production is believed to grow the forecast for the year 2003 being approximately 800 Mt. Electric arc furnace production is estimated to reach 280 Mt by 2003, and BOFIOH will reach 520 Mt by 2003. The current status of the converter steelmaking process is briefly described both on its theoretical bases and practical technological progresses. Developments which significantly improve the process are briefly discussed. Several more recent developments such as combined oxygen blowing process, increased scrap melting, post combustion and hot metal pretreatment are discussed. The future progress will be in further development of these process characteristics as well as in eventual emerging of the continuous converter process. (author)

  1. A Buck-Boost Converter Modified to Utilize 600V GaN Power Devices in a PV Application Requiring 1200V Devices

    Directory of Open Access Journals (Sweden)

    SRDIC, S.

    2015-08-01

    Full Text Available This paper presents a buck-boost converter which is modified to utilize new 600 V gallium nitride (GaN power semiconductor devices in an application requiring 1200 V devices. The presented buck-boost converter is used as a part of a dc/dc stage in an all-GaN photovoltaic (PV inverter and it provides a negative voltage for the 3-level neutral-point-clamped (NPC PWM inverter which is connected to the utility grid. Since in this application the transistor and the diode of the buck-boost converter need to block the sum of the PV string voltage (which is normally in the range from 150 to 350 V and the dc bus voltage (which is in the order of 400 V, the 1200 V devices or series connection of 600 V devices need to be employed. Currently, 1200 V GaN power semiconductor devices are not commercially available. Therefore, the standard buck-boost converter is modified to enable the use of 600 V GaN devices in this particular application. Based on the proposed converter topology, a PSpice simulation model and a 600 W converter prototype were developed. Both simulation and experimental results show successful operation of the converter.

  2. Compound control method of neutral point voltage of three level NPC inverter based on the vector method of virtual space and hysteresis control

    Science.gov (United States)

    Yang, Fengping; Xiao, Fangfei

    2017-03-01

    Current control methods include hardware control and software control corresponding to the inherent unbalance problem of neutral point voltage in three level NPC inverter. The hardware control is rarely used due to its high cost. In this paper, a new compound control method has been presented based on the vector method of virtual space and traditional hysteresis control of neutral point voltage, which can make up the shortcoming of the virtual control without the feedback control system of neutral point voltage and the blind area of hysteresis control and control the deviation and wave of neutral point voltage. The accuracy of this method has been demonstrated by simulation.

  3. Intrapulmonary activation of the angiotensin-converting enzyme type 2/angiotensin 1-7/G-protein-coupled Mas receptor axis attenuates pulmonary hypertension in Ren-2 transgenic rats exposed to chronic hypoxia.

    Science.gov (United States)

    Hampl, V; Herget, J; Bíbová, J; Baňasová, A; Husková, Z; Vaňourková, Z; Jíchová, Š; Kujal, P; Vernerová, Z; Sadowski, J; Červenka, L

    2015-01-01

    The present study was performed to evaluate the role of intrapulmonary activity of the two axes of the renin-angiotensin system (RAS): vasoconstrictor angiotensin-converting enzyme (ACE)/angiotensin II (ANG II)/ANG II type 1 receptor (AT₁) axis, and vasodilator ACE type 2 (ACE2)/angiotensin 1-7 (ANG 1-7)/Mas receptor axis, in the development of hypoxic pulmonary hypertension in Ren-2 transgenic rats (TGR). Transgene-negative Hannover Sprague-Dawley (HanSD) rats served as controls. Both TGR and HanSD rats responded to two weeks´ exposure to hypoxia with a significant increase in mean pulmonary arterial pressure (MPAP), however, the increase was much less pronounced in the former. The attenuation of hypoxic pulmonary hypertension in TGR as compared to HanSD rats was associated with inhibition of ACE gene expression and activity, inhibition of AT₁receptor gene expression and suppression of ANG II levels in lung tissue. Simultaneously, there was an increase in lung ACE2 gene expression and activity and, in particular, ANG 1-7 concentrations and Mas receptor gene expression. We propose that a combination of suppression of ACE/ANG II/AT₁receptor axis and activation of ACE2/ANG 1-7/Mas receptor axis of the RAS in the lung tissue is the main mechanism explaining attenuation of hypoxic pulmonary hypertension in TGR as compared with HanSD rats.

  4. Activation of miR-21 by STAT3 induces proliferation and suppresses apoptosis in nasopharyngeal carcinoma by targeting PTEN gene.

    Directory of Open Access Journals (Sweden)

    Hesheng Ou

    Full Text Available The present study is to investigate the role of microRNA-21 (miR-21 in nasopharyngeal carcinoma (NPC and the mechanisms of regulation of PTEN by miR-21. Fifty-four tissue samples were collected from 42 patients with NPC and 12 healthy controls. Human NPC cell lines CNE-1, CNE-2, TWO3 and C666-1 were used for cell assays. To investigate the expression of miR-21, RT-PCR was employed. RT-PCR, Western blotting, and immunohistochemistry were used to measure the expression of STAT3 mRNA and STAT3 protein. To test the effect of miR-21 on the cell growth and apoptosis of NPC cells in vitro, transfection of CNE1 and CNE2 cell lines and flow cytometry were performed. TUNEL assay was used to detect DNA fragmentation. To validate whether miR-21 directly recognizes the 3'-UTRs of PTEN mRNA, luciferase reporter assay was employed. miR-21 expression was increased in NPC tissues compared with control and the same result was found in NPC cell lines. Notably, increased expression of miR-21 was directly related to advanced clinical stage and lymph node metastasis. STAT3, a transcription factor activated by IL-6, directly activated miR-21 in transformed NPC cell lines. Furthermore, miR-21 markedly inhibited PTEN tumor suppressor, leading to increased AKT activity. Both in vitro and in vivo assays revealed that miR-21 enhanced NPC cell proliferation and suppressed apoptosis. miR-21, activated by STAT3, induced proliferation and suppressed apoptosis in NPC by targeting PTEN-AKT pathway.

  5. The Simulation of DFIG Grid Side Converter

    National Research Council Canada - National Science Library

    LU Yan-Ling; LU Jian-qiang; BAO Jie

    2017-01-01

    Firstly,DFIG basic structure of grid side converter was analyzed according to basic principles of voltage converter, and a mathematical model of grid side converter was established in the three-phase...

  6. Impedance Coordinative Control for Cascaded Converter in Bidirectional Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe

    2015-01-01

    Two stage cascaded converters are widely used in bidirectional applications, but the negative impedance may cause system instability. Actually the impedance interaction is much different between forward power flow and reversed power flow, which will introduce more uncertainty to the system...... stability. This paper proposes a control method for the constant power controlled converter in cascaded system, and consequently it can change the negative impedance of constant power converter into resistive impedance, which will improve the cascaded system stability, as well as merge the impedance...... difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dual-active-bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system...

  7. Reducing GBA2 Activity Ameliorates Neuropathology in Niemann-Pick Type C Mice.

    Directory of Open Access Journals (Sweden)

    André R A Marques

    Full Text Available The enzyme glucocerebrosidase (GBA hydrolyses glucosylceramide (GlcCer in lysosomes. Markedly reduced GBA activity is associated with severe manifestations of Gaucher disease including neurological involvement. Mutations in the GBA gene have recently also been identified as major genetic risk factor for Parkinsonism. Disturbed metabolism of GlcCer may therefore play a role in neuropathology. Besides lysosomal GBA, cells also contain a non-lysosomal glucosylceramidase (GBA2. Given that the two β-glucosidases share substrates, we speculated that over-activity of GBA2 during severe GBA impairment might influence neuropathology. This hypothesis was studied in Niemann-Pick type C (Npc1-/- mice showing secondary deficiency in GBA in various tissues. Here we report that GBA2 activity is indeed increased in the brain of Npc1-/- mice. We found that GBA2 is particularly abundant in Purkinje cells (PCs, one of the most affected neuronal populations in NPC disease. Inhibiting GBA2 in Npc1-/- mice with a brain-permeable low nanomolar inhibitor significantly improved motor coordination and extended lifespan in the absence of correction in cholesterol and ganglioside abnormalities. This trend was recapitulated, although not to full extent, by introducing a genetic loss of GBA2 in Npc1-/- mice. Our findings point to GBA2 activity as therapeutic target in NPC.

  8. Modeling of asymmetrical boost converters

    Directory of Open Access Journals (Sweden)

    Eliana Isabel Arango Zuluaga

    2014-01-01

    Full Text Available The asymmetrical interleaved dual boost (AIDB is a fifth-order DC/DC converter designed to interface photovoltaic (PV panels. The AIDB produces small current harmonics to the PV panels, reducing the power losses caused by the converter operation. Moreover, the AIDB provides a large voltage conversion ratio, which is required to step-up the PV voltage to the large dc-link voltage used in grid-connected inverters. To reject irradiance and load disturbances, the AIDB must be operated in a closed-loop and a dynamic model is required. Given that the AIDB converter operates in Discontinuous Conduction Mode (DCM, classical modeling approaches based on Continuous Conduction Mode (CCM are not valid. Moreover, classical DCM modeling techniques are not suitable for the AIDB converter. Therefore, this paper develops a novel mathematical model for the AIDB converter, which is suitable for control-pur-poses. The proposed model is based on the calculation of a diode current that is typically disregarded. Moreover, because the traditional correction to the second duty cycle reported in literature is not effective, a new equation is designed. The model accuracy is contrasted with circuital simulations in time and frequency domains, obtaining satisfactory results. Finally, the usefulness of the model in control applications is illustrated with an application example.

  9. Modeling of asymmetrical boost converters

    Directory of Open Access Journals (Sweden)

    Eliana Isabel Arango Zuluaga

    2014-03-01

    Full Text Available The asymmetrical interleaved dual boost (AIDB is a fifth-order DC/DC converter designed to interface photovoltaic (PV panels. The AIDB produces small current harmonics to the PV panels, reducing the power losses caused by the converter operation. Moreover, the AIDB provides a large voltage conversion ratio, which is required to step-up the PV voltage to the large dc-link voltage used in grid-connected inverters. To reject irradiance and load disturbances, the AIDB must be operated in a closed-loop and a dynamic model is required. Given that the AIDB converter operates in Discontinuous Conduction Mode (DCM, classical modeling approaches based on Continuous Conduction Mode (CCM are not valid. Moreover, classical DCM modeling techniques are not suitable for the AIDB converter. Therefore, this paper develops a novel mathematical model for the AIDB converter, which is suitable for control-pur-poses. The proposed model is based on the calculation of a diode current that is typically disregarded. Moreover, because the traditional correction to the second duty cycle reported in literature is not effective, a new equation is designed. The model accuracy is contrasted with circuital simulations in time and frequency domains, obtaining satisfactory results. Finally, the usefulness of the model in control applications is illustrated with an application example.

  10. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    . Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. Thisimplicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development...... stages, and results thereby in a need for specific testobjectives and procedures for each development stage. This PhD thesis has looked into the different development stages and more specifically in the performance assessment of wave energy converters based on tank testing and sea trials. The objective......Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into waveenergy has been undertaken for decades, a significant increase in related activities has been seen in the recent years...

  11. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    . Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. This implicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development...... stages, and results thereby in a need for specific test objectives and procedures for each development stage. This PhD thesis has looked into the different development stages and more specifically in the performance assessment of wave energy converters based on tank testing and sea trials. The objective......Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into wave energy has been undertaken for decades, a significant increase in related activities has been seen in the recent years...

  12. CAR T Cells Releasing IL-18 Convert to T-Bethigh FoxO1low Effectors that Exhibit Augmented Activity against Advanced Solid Tumors

    Directory of Open Access Journals (Sweden)

    Markus Chmielewski

    2017-12-01

    Full Text Available Adoptive therapy with chimeric antigen receptor (CAR-redirected T cells has achieved remarkable efficacy in the treatment of hematopoietic malignancies. However, eradicating large solid tumors in advanced stages of the disease remains challenging. We explored augmentation of the anti-tumor immune reaction by establishing an acute inflammatory reaction. Systematic screening indicates that IL-18 polarizes CAR T cells toward T-bethigh FoxO1low effectors with an acute inflammatory response. CAR T cells engineered with inducible IL-18 release exhibited superior activity against large pancreatic and lung tumors that were refractory to CAR T cells without cytokines. IL-18 CAR T cell treatment was accompanied by an overall change in the immune cell landscape associated with the tumor. More specifically, CD206− M1 macrophages and NKG2D+ NK cells increased in number, whereas Tregs, suppressive CD103+ DCs, and M2 macrophages decreased, suggesting that “iIL18 TRUCKs” can be used to sensitize large solid tumor lesions for successful immune destruction.

  13. Iridium Cyclooctene Complex That Forms a Hyperpolarization Transfer Catalyst before Converting to a Binuclear C-H Bond Activation Product Responsible for Hydrogen Isotope Exchange.

    Science.gov (United States)

    Iali, Wissam; Green, Gary G R; Hart, Sam J; Whitwood, Adrian C; Duckett, Simon B

    2016-11-21

    [IrCl(COE)2]2 (1) reacts with pyridine (py) and H2 to form crystallographically characterized IrCl(H)2(COE)(py)2 (2). 2 undergoes py loss to form 16-electron IrCl(H)2(COE)(py) (3), with equivalent hydride ligands. When this reaction is studied with parahydrogen, 1 efficiently achieves hyperpolarization of free py (and nicotinamide, nicotine, 5-aminopyrimidine, and 3,5-lutudine) via signal amplification by reversible exchange (SABRE) and hence reflects a simple and readily available precatayst for this process. 2 reacts further over 48 h at 298 K to form crystallographically characterized (Cl)(H)(py)(μ-Cl)(μ-H)(κ-μ-NC5H4)Ir(H)(py)2 (4). This dimer is active in the hydrogen isotope exchange process that is used in radiopharmaceutical preparations. Furthermore, while [Ir(H)2(COE)(py)3]PF6 (6) forms upon the addition of AgPF6 to 2, its stability precludes its efficient involvement in SABRE.

  14. Sodium restriction potentiates the renoprotective effects of combined vitamin D receptor activation and angiotensin-converting enzyme inhibition in established proteinuric nephropathy.

    Science.gov (United States)

    Mirkovic, Katarina; Frenay, Anne-Roos S; van den Born, Jacob; van Goor, Harry; Navis, Gerjan; de Borst, Martin H

    2017-08-01

    Renin-angiotensin-aldosterone system (RAAS) blockade provides renoprotective effects in chronic kidney disease (CKD); yet progressive renal function loss remains common. Dietary sodium restriction potentiates the renoprotective effects of RAAS blockade. Vitamin D receptor activator (VDRA) treatment reduces proteinuria, inflammation and fibrosis, but whether these effects depend on sodium intake has not been studied. We hypothesized that the renoprotective effects of VDRA treatment, with or without RAAS blockade, are modulated by sodium intake. Six weeks after the induction of adriamycin nephrosis in Wistar rats, i.e. with established proteinuria, animals were treated with the VDRA paricalcitol, lisinopril, the combination, or vehicle; each treatment was given during either a high- (2% NaCl) or a low-sodium (0.05% NaCl) diet for 6 weeks. We assessed proteinuria, blood pressure, renal macrophage accumulation and renal expression of the pre-fibrotic marker alpha-smooth muscle actin (α-SMA) at the end of the treatment. Both paricalcitol and lisinopril individually, as well as in combination, reduced proteinuria and glomerular and interstitial inflammation during a low-sodium diet, but not during a high-sodium diet. All interventions also reduced focal glomerulosclerosis and interstitial expression of α-SMA during the low-sodium diet, while similar trends were observed during the high-sodium diet. The renoprotective effects of paricalcitol were not accompanied by blood pressure reduction. As proteinuria was already abolished by lisinopril during the low-sodium diet, the addition of paricalcitol had no further effect on proteinuria or downstream inflammatory or pre-fibrotic changes. The renoprotective effects of the VDRA paricalcitol are blood pressure independent but do depend on dietary sodium status. The combination of RAAS blockade, dietary sodium restriction and VDRA may be a promising intervention to further retard renal function loss in CKD.

  15. The Boost Converter – Revisited

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2015-12-01

    Full Text Available The dc-to-dc boost converter is a single-switch, single-inductor, switching circuit used to efficiently transform energy from one dc voltage level to a greater voltage level of the same relative polarity. For a specific resistive load range, as the duty cycle decreases, the boost converter inductor enters a discontinuous current mode of operation - the output load current having decreased to a definable level. This paper analyses the fact that a further reduction of load current, as the duty cycle decreases towards zero, will always result in the re-emergence of a continuous inductor current condition. Further, at the other load extreme, high-current, progressively for increasing load current, starting at low duty cycle conditions, the minimum inductor current always increases from a fixed normalised current level, for a specific load range. These and other hitherto unexplored boost converter properties are analysed and verified mathematically and with PSpice simulations. 

  16. Genetic variation in ABC G5/G8 and NPC1L1 impact cholesterol response to plant sterols in hypercholesterolemic men.

    Science.gov (United States)

    Zhao, Hai L; Houweling, Adrielle H; Vanstone, Catherine A; Jew, Stephanie; Trautwein, Elke A; Duchateau, Guus S M J E; Jones, Peter J H

    2008-12-01

    ATP-binding cassette hetero-dimeric transporters G5 and G8 (ABCG5/G8) have been postulated to mediate intestinal cholesterol efflux, whereas Niemann-Pick C1 Like 1 (NPC1L1) protein is believed to be essential for intestinal cholesterol influx. The individual or combined genetic markers, such as single nuclear polymorphisms (SNPs), of these two transporter genes may explain inter-individual variations in plasma cholesterol response following plant sterol (PS) intervention. The present study was aimed at investigating the association between ABCG5/G8 and NPC1L1 genotype SNPs with sterol absorption and corresponding plasma concentrations. The study used a 4-week crossover design with 82 hypercholesterolemic men characterized by high vs. low basal plasma PS concentrations consuming spreads with or without 2 g/day of PS. For the ABCG8 1289 C > A (T400 K) polymorphism, the A allele carriers with high basal plasma PS concentrations demonstrated a 3.9-fold greater reduction (p G (L272L) and 3929 G > A (Y1291Y), individuals carrying mutant alleles showed a 2.4-fold greater (p < 0.05) reduction in LDL-C levels, compared to wild type counterparts. Results suggest that genetic and metabolic biomarkers together may predict inter-individual lipid level responsiveness to PS-intervention, and thus could be useful in devising individualized cholesterol lowering strategies.

  17. Simplified design of data converters

    CERN Document Server

    Lenk, John

    1997-01-01

    Simplified Design of Data Converters shows how to design and experiment with data converters, both analog-to-digital and digital to analog. The design approach here is the same one used in all of John Lenk's best-selling books on simplified and practical design. Throughout the book, design problems start with guidelines for selecting all components on a trial-value basis, assuming a specific design goal and set of conditions. Then, using the guideline values in experimental circuits, the desired results are produced by varying the experimental component values, if needed.If you are a w

  18. The Evaluation of Dipeptidyl Peptidase (DPP)-IV, α-Glucosidase and Angiotensin Converting Enzyme (ACE) Inhibitory Activities of Whey Proteins Hydrolyzed with Serine Protease Isolated from Asian Pumpkin (Cucurbita ficifolia).

    Science.gov (United States)

    Konrad, Babij; Anna, Dąbrowska; Marek, Szołtysik; Marta, Pokora; Aleksandra, Zambrowicz; Józefa, Chrzanowska

    2014-01-01

    In the present study, whey protein concentrate (WPC-80) and β-lactoglobulin were hydrolyzed with a noncommercial serine protease isolated from Asian pumpkin (Cucurbita ficifolia). Hydrolysates were further fractionated by ultrafiltration using membranes with cut-offs equal 3 and 10 kDa. Peptide fractions of molecular weight lower than 3 and 3-10 kDa were further subjected to the RP-HPLC. Separated preparations were investigated for their potential as the natural inhibitors of dipeptidyl peptidase (DPP-IV), α-glucosidase and angiotensin converting enzyme (ACE). WPC-80 hydrolysate showed higher inhibitory activities against the three tested enzymes than β-lactoglobulin hydrolysate. Especially high biological activities were exhibited by peptide fractions of molecular weight lower than 3 kDa, with ACE IC50 <0.64 mg/mL and DPP-IV IC50 <0.55 mg/mL. This study suggests that peptides generated from whey proteins may support postprandial glycemia regulation and blood pressure maintenance, and could be used as functional food ingredients in the diet of patients with type 2 diabetes.

  19. Charge-pump voltage converter

    Science.gov (United States)

    Brainard, John P [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  20. A digital to analog converter

    NARCIS (Netherlands)

    Westra, Jan R.; Annema, Anne J.

    2000-01-01

    A digital to analog converter for a multibit digital input signal has a set of conversion elements for the positive signal excursions and a set of conversion elements for the negative signal excursions. In each set the conversion elements are selected according to a dynamic element matching

  1. A digital to analog converter

    NARCIS (Netherlands)

    Westra, Jan R.; Annema, Anne J.

    2006-01-01

    A digital to analog converter for a multibit digital input signal has a set of conversion elements for the positive signal excursions and a set of conversion elements for the negative signal excursions. In each set the conversion elements are selected according to a dynamic element matching

  2. XML Docbook to Mediawiki Converter

    Directory of Open Access Journals (Sweden)

    Maria Chiara Pievatolo

    2013-05-01

    Full Text Available A Perl script, based on the work of Stefano Selleri, to migrate XML-Docbook 4.X documents to Wiki markup. I added some lines to meet my need to convert my Kant translations from Docbook to MediaWiki. A sample of the output can be...

  3. 21 CFR 862.1090 - Angiotensin converting enzyme (A.C.E.) test system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Angiotensin converting enzyme (A.C.E.) test system... Test Systems § 862.1090 Angiotensin converting enzyme (A.C.E.) test system. (a) Identification. An angiotensin converting enzyme (A.C.E.) test system is a device intended to measure the activity of angiotensin...

  4. Multilevel converters for power system applications

    Energy Technology Data Exchange (ETDEWEB)

    Lai, J.S.; Stovall, J.P. [Oak Ridge National Lab., TN (United States); Peng, F.Z. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States)

    1995-09-01

    Multilevel converters are emerging as a new breed of power converter options for power system applications. These converters are most suitable for high voltage high power applications because they connect devices in series without the need for component matching. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. To avoid voltage unbalance between different levels, several techniques have been proposed for different applications. Excluding magnetic-coupled converters, this paper introduces three multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded inverters with separate dc sources. The operation principle, features, constraints, and potential applications of these converters will be discussed.

  5. Activation of lytic cycle of Epstein-Barr virus by suberoylanilide hydroxamic acid leads to apoptosis and tumor growth suppression of nasopharyngeal carcinoma.

    Science.gov (United States)

    Hui, K F; Ho, Dona N; Tsang, C M; Middeldorp, Jaap M; Tsao, George S W; Chiang, Alan K S

    2012-10-15

    Nasopharyngeal carcinoma (NPC) is strongly associated with Epstein-Barr virus (EBV). We reported that suberoylanilide hydroxamic acid (SAHA) induced EBV lytic cycle in EBV-positive gastric carcinoma cells and mediated enhanced cell death. However, expression of EBV lytic proteins was thought to exert antiapoptotic effect in EBV-infected cells. Here, we examined the in vitro and in vivo effects of SAHA on EBV lytic cycle induction in NPC cells and investigated the cellular consequences. Micromolar concentrations of SAHA significantly induced EBV lytic cycle in EBV-positive NPC cells. Increased apoptosis and proteolytic cleavage of poly(ADP-ribose) polymerase and caspase-3, -7 and -9 in EBV-positive versus EBV-negative NPC cells were observed. More than 85% of NPC cells expressing immediate-early (Zta), early (BMRF1) or late (gp350/220) lytic proteins coexpressed cleaved caspase-3. Tracking of expression of EBV lytic proteins and cleaved caspase-3 over time demonstrated that NPC cells proceeded to apoptosis following EBV lytic cycle induction. Inhibition of EBV DNA replication and late lytic protein expression by phosphonoformic acid did not impact on SAHA's induced cell death in NPC, indicating that early rather than late phase of EBV lytic cycle contributed to the apoptotic effect. In vivo effects of SAHA on EBV lytic cycle induction and tumor growth suppression were also observed in NPC xenografts in nude mice. Taken together, our data indicated that activation of lytic cycle from latent cycle of EBV by SAHA leads to apoptosis and tumor growth suppression of NPC thereby providing experimental evidence for virus-targeted therapy against EBV-positive cancer. Copyright © 2012 UICC.

  6. Effect of naturally random allocation to lower low-density lipoprotein cholesterol on the risk of coronary heart disease mediated by polymorphisms in NPC1L1, HMGCR, or both: a 2 × 2 factorial Mendelian randomization study.

    Science.gov (United States)

    Ference, Brian A; Majeed, Faisal; Penumetcha, Raju; Flack, John M; Brook, Robert D

    2015-04-21

    Considerable uncertainty exists as to whether lowering low-density lipoprotein cholesterol (LDL-C) by inhibiting the Niemann-Pick C1-Like 1 (NPC1L1) receptor with ezetimibe, either alone or in combination with a 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) inhibitor (statin), will reduce the risk of coronary heart disease (CHD). This study evaluated the effect of naturally random allocation to lower LDL-C mediated by polymorphisms in the NPC1L1 gene (target of ezetimibe), the HMGCR gene (target of statins), or both (target of combination therapy) on the risk of CHD. We constructed NPC1L1 and HMGCR genetic LDL-C scores to naturally randomize participants into 4 groups: reference, lower LDL-C mediated by NPC1L1 polymorphisms, lower LDL-C mediated by HMGCR polymorphisms, or lower LDL-C mediated by polymorphisms in both NPC1L1 and HMGCR. We compared the risk of CHD (fatal or nonfatal myocardial infarction) among each group using a 2 × 2 factorial mendelian randomization study design. A total of 108,376 persons (10,464 CHD events) from 14 studies were included. There were no significant differences in baseline characteristics among the 4 groups, thus confirming that allocation was random. Compared to the reference group, the NPC1L1 group had 2.4 mg/dl lower LDL-C and 4.8% lower risk of CHD (odds ratio [OR]: 0.952, 95% confidence interval [CI]: 0.920 to 0.985); whereas the HMGCR group had 2.9 mg/dl lower LDL-C and a similar 5.3% lower risk of CHD (OR: 0.947, 95% CI: 0.909 to 0.986). The group with lower LDL-C mediated by both NPC1L1 and HMGCR polymorphisms had 5.8 mg/dl additively lower LDL-C and a 10.8% log-linearly additive lower risk of CHD (OR: 0.892, 95% CI: 0.854 to 0.932). The effect of lower LDL-C on the risk of CHD mediated by polymorphisms in NPC1L1, HMGCR, or both is approximately the same per unit lower LDL-C and log-linearly proportional to the absolute exposure to lower LDL-C. Copyright © 2015 American College of Cardiology Foundation

  7. Design, modeling and testing of data converters

    CERN Document Server

    Kiaei, Sayfe; Xu, Fang

    2014-01-01

    This book presents the a scientific discussion of the state-of-the-art techniques and designs for modeling, testing and for the performance analysis of data converters. The focus is put on sustainable data conversion. Sustainability has become a public issue that industries and users can not ignore. Devising environmentally friendly solutions for data conversion designing, modeling and testing is nowadays a requirement that researchers and practitioners must consider in their activities. This book presents the outcome of the IWADC workshop 2011, held in Orvieto, Italy.

  8. Near-Shore Floating Wave Energy Converters

    DEFF Research Database (Denmark)

    Ruol, Piero; Zanuttigh, Barbara; Martinelli, Luca

    2011-01-01

    Aim of this note is to analyse the possible application of a Wave Energy Converter (WEC) as a combined tool to protect the coast and harvest energy. Physical model tests are used to evaluate wave transmission past a near-shore floating WEC of the wave activated body type, named DEXA. Efficiency...... and transmission characteristics are approximated to functions of wave height, period and obliquity. Their order of magnitude are 20% and 80%, respectively. It is imagined that an array of DEXA is deployed in front of Marina di Ravenna beach (IT), a highly touristic site of the Adriatic Coast. Based on the CERC...

  9. Multilevel push pull power converter

    DEFF Research Database (Denmark)

    2007-01-01

    A power converter for converting an input voltage (Vin) into an output voltage (Vout), comprising a first supply potential and a second supply potential established by the input voltage, and at least one primary winding having two terminals, a center tap arranged between the two terminals...... and connected to the first supply potential, and at least one secondary winding magnetically coupled to the primary winding for providing at least one output voltage (Vout); and a first controllable switch connected between the second supply potential and one terminal of the primary winding and a second...... controllable switch connected between the second supply potential and the other terminal of the primary winding and a third controllable switch connected between the second supply potential and the one terminal of the primary winding and a fourth controllable switch connected between the second supply...

  10. Radiated EMI from power converters

    Directory of Open Access Journals (Sweden)

    Arnautovski-Toševa Vesna

    2005-01-01

    Full Text Available With the continuous increase of switching frequency together with the ongoing trend to higher complexity and functionality, power converters as a part of electronic systems have raised more and more electromagnetic energy pollution to the local system environment. In the same time, stringent demands are imposed on the designers of new circuits that electromagnetic interference (EMI has to be suppressed at its source before it is allowed to propagate into other circuits and systems. In this paper, the authors present a full-wave numerical method for calculation and simulation of electromagnetic field radiated by power converter circuitry. The main objective is to analyze the layout geometry in order to obtain competitive PCB layout that will enable suitably attenuated level of the radiated electric field to safe level. By this it would be possible to ensure reliable operation of the sensitive electronic components in the proximity.

  11. A digital to analog converter

    OpenAIRE

    Westra, Jan R.; Annema, Anne J.

    2000-01-01

    A digital to analog converter for a multibit digital input signal has a set of conversion elements for the positive signal excursions and a set of conversion elements for the negative signal excursions. In each set the conversion elements are selected according to a dynamic element matching algorithm. To improve the mismatch-noise shaping of these algorithms, excess conversion elements may be additionally selected.

  12. Development of a Compact Matrix Converter

    Directory of Open Access Journals (Sweden)

    J. Bauer

    2009-01-01

    Full Text Available This paper deals with the development of a matrix converter. Matrix converters belong to the category of direct frequency converters. A converter does not contain DC-link and the output voltage is provided by direct switching of voltage from the input phases. This is enabled by 9 bidirectional switches, which are provided by anti-serial connection of 18 IGBT transistors. The absence of a DC-link is great advantage of the matrix converter, but it also increases the requirements on the converter control. For this reason a new prototype of a matrix converter is being developed with sophisticated modern components (FPGA, Power PC equipped in the control part of the converter. The converter will be used for testing new control algorithms and commutation methods. 

  13. Computerized simulation of converter process

    Energy Technology Data Exchange (ETDEWEB)

    Jalkanen, H.; Suomi, M.L.; Wallgren, M. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Metallurgy

    1996-12-31

    Converter process is essentially an oxidising refining process aiming in addition to (1) the primary refining action, decarburisation of high carbon iron melt, also to (2) maximal elimination of impurity elements, especially silicon, phosphorus and sulphur, (3) melting of substantial amounts of scrap using the extra heat released in oxidation reactions and (4) to exact final steel temperature control, optimal for further treatments. `Quantitative modelling of such a complex non-stationary chemical process as oxygen converting necessitates extensive formulation of chemical and thermal evolution of the process in connection with the technological properties of the reactor and the process control measures. A comprehensive converter simulation program like CONSIM-3. 1 and its preceding versions that is based on the theoretical and practical knowledge on the process can be used for (1) educating specialists and smelter personnel, (2) planning of the blowing programs, (3) developing and testing of process control systems and after some elaboration and restructuring (4) it can be integrated to static or dynamic process control systems. (orig.) SULA 2 Research Programme; 10 refs.

  14. High efficiency thermionic converter studies

    Science.gov (United States)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, D. P.; Oettinger, P. E.

    1976-01-01

    The objective is to improve thermionic converter performance by means of reduced interelectrode losses, greater emitter capabilities, and lower collector work functions until the converter performance level is suitable for out-of-core space reactors and radioisotope generators. Electrode screening experiments have identified several promising collector materials. Back emission work function measurements of a ZnO collector in a thermionic diode have given values less than 1.3 eV. Diode tests were conducted over the range of temperatures of interest for space power applications. Enhanced mode converter experiments have included triodes operated in both the surface ionization and plasmatron modes. Pulsed triodes were studied as a function of pulse length, pulse potential, inert gas fill pressure, cesium pressure, spacing, emitter temperature and collector temperature. Current amplifications (i.e., mean output current/mean grid current) of several hundred were observed up to output current densities of one amp/sq cm. These data correspond to an equivalent arc drop less than 0.1 eV.

  15. Simulation and Modeling of a Five -Level (NPC Inverter Fed by a Photovoltaic Generator and Integrated in a Hybrid Wind-PV Power System

    Directory of Open Access Journals (Sweden)

    M. Rezki,

    2017-08-01

    Full Text Available A distributed hybrid coordinated wind photovoltaic (PV power system was proposed in this paper. As oil and coal reserves are being depleted whilst at the same time the energy demand is growing, it is important to consider alternative energy generating techniques. Today, the five-level (NPC inverter represents a good alternative for several industrial applications. To take advantage of the five-level inverter topology and the benefits of renewable energy represented by a photovoltaic generator, a new scheme of these controllers is proposed in this work. This paper outlines the design of a hybrid power system consisting of a solar photovoltaic (PV and a wind power system. The system is modeled in Matlab Simulink and tested for various conditions. The model and results are discussed in this paper.

  16. Simulation Results of Double Forward Converter

    Directory of Open Access Journals (Sweden)

    P. Vijaya KUMAR

    2009-12-01

    Full Text Available This work aims to find a better forward converter for DC to DC conversion.Simulation of double forward converter in SMPS system is discussed in this paper. Aforward converter with RCD snubber to synchronous rectifier and/or to current doubleris also discussed. The evolution of the forward converter is first reviewed in a tutorialfashion. Performance parameters are discussed including operating principle, voltageconversion ratio, efficiency, device stress, small-signal dynamics, noise and EMI. Itscircuit operation and its performance characteristics of the forward converter with RCDsnubber and double forward converter are described and the simulation results arepresented.

  17. Device Loading of Modular Multilevel Converter in Wind Power

    DEFF Research Database (Denmark)

    Popova, L.; Ma, Ke; Blaabjerg, Frede

    2015-01-01

    Modular multilevel converter (MMC) is a recently emerged multilevel topology for high-voltage high-power applications. However, in wind power applications, to the best of the authors knowledge, the performance of the MMC has not been extensively investigated. In this paper, the application...... of the MMC to wind energy systems is studied. The converters used to connect the wind turbine to the grid, which have rated active powers of 2MW and 10MW, are proposed and investigated. The electrical losses and thermal loading of the power devices in the proposed converter solutions are analyzed based...... on the gird conditions/requirements for wind power. The efficiency of the MMC under different P/Q boundaries defined by grid codes is investigated and compared with two-level (2L) and three-level (3L) neutral point clamped converters. It is concluded that it is possible to use the MMC in wind power...

  18. A Single Switch Dual Output Non-Isolated Boost Converter

    DEFF Research Database (Denmark)

    Klimczak, Pawel; Munk-Nielsen, Stig

    2008-01-01

    very simple dual output non-isolated boost converter is presented. Single active switch is used to control both, positive and negative output voltages. The converter is desired to boost unregulated low input voltage 25-50 Vdc to regulated high voltage ±400 Vdc in dual dc-link. In this paper proposed......There are many applications for high gain dc-dc converters. In several of these applications galvanic isolation is not required, but there are some safety issues regarding missing isolation and leakage current. Usage of a half-bridge inverter and a dual dc-link may solve this issues. In this paper...... topology is analyzed and explained. Obtained experimental results prove good performance of the converter over wide range of input voltage and output power....

  19. Grid Connected Solar PV System with SEPIC Converter Compared with Parallel Boost Converter Based MPPT

    Directory of Open Access Journals (Sweden)

    T. Ajith Bosco Raj

    2014-01-01

    Full Text Available The main objective of this work is to study the behaviour of the solar PV systems and model the efficient Grid-connected solar power system. The DC-DC MPPT circuit using chaotic pulse width modulation has been designed to track maximum power from solar PV module. The conversion efficiency of the proposed MPPT system is increased when CPWM is used as a control scheme. This paper also proposes a simplified multilevel (seven level inverter for a grid-connected photovoltaic system. The primary goal of these systems is to increase the energy injected to the grid by keeping track of the maximum power point of the panel, by reducing the switching frequency, and by providing high reliability. The maximum power has been tracked experimentally. It is compared with parallel boost converter. Also this model is based on mathematical equations and is described through an equivalent circuit including a PV source with MPPT, a diode, a series resistor, a shunt resistor, and dual boost converter with active snubber circuit. This model can extract PV power and boost by using dual boost converter with active snubber. By using this method the overall system efficiency is improved thereby reducing the switching losses and cost.

  20. Electromechanical converters for electric vehicles

    Science.gov (United States)

    Ambros, T.; Burduniuc, M.; Deaconu, S. I.; Rujanschi, N.

    2018-01-01

    The paper presents the analysis of various constructive schemes of synchronous electromechanical converters with permanent magnets fixed on the rotor and asynchronous with the short-circuit rotor. Various electrical stator winding schemes have also been compared, demonstrating the efficiency of copper utilization in toroidal windings. The electromagnetic calculus of the axial machine has particularities compared to the cylindrical machine, in the paper is presented the method of correlating the geometry of the cylindrical and axial machines. In this case the method and recommendations used in the design of such machines may be used.

  1. OAM mode converter in twisted fibers

    DEFF Research Database (Denmark)

    Usuga Castaneda, Mario A.; Beltran-Mejia, Felipe; Cordeiro, Cristiano

    2014-01-01

    We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA.......We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA....

  2. Plasma renin activity to plasma aldosterone concentration ratio correlates with night-time and pulse pressures in essential hypertensive patients treated with angiotensin-converting enzyme inhibitors/AT1 blockers.

    Science.gov (United States)

    Spannella, Francesco; Giulietti, Federico; Balietti, Paolo; Borioni, Elisabetta; Lombardi, Francesca E; Ricci, Maddalena; Cocci, Guido; Landi, Laura; Sarzani, Riccardo

    2017-11-01

    Angiotensin-converting enzyme inhibitors (ACE-I) and AT1 blockers (ARB) are commonly used antihypertensive drugs, but several factors may affect their effectiveness. We evaluated the associations between ambulatory blood pressure (BP) monitoring (ABPM) parameters and plasma renin activity (PRA)-to-plasma aldosterone concentration (PAC) ratio (RAR) to test renin-angiotensin-aldosterone system inhibition in essential hypertensive patients treated with ACE-I or ARB for at least 12 months. We evaluated 194 consecutive patients referred to our Hypertension Centre. ABPM, PRA and PAC tests were performed without any changes in drug therapy. RAR, PRA and PAC tertiles were considered for the analyses. Mean age: 57.4 ± 12.0 years; male prevalence: 63.9%. No differences between RAR tertiles regarding the use of ACE-I or ARB (P = 0.385), as well as the other antihypertensive drug classes, were found. A reduction of all ABPM values considered (24-h BP, daytime BP and night-time BP and 24-h pulse pressure (PP), daytime PP and night-time PP) and a better BP control were observed at increasing RAR tertiles, with an odds ratio = 0.12 to be not controlled during night-time period for patients in the third tertile compared with patients in the first tertile (P < 0.001). This association remained significant even after adjusting for 24-h BP control. All the associations were also confirmed for PRA tertiles, but not for PAC tertiles. Higher RAR values indicate effective renin-angiotensin-aldosterone system inhibition and lower night-time and pulse pressures in real-life clinical practice. It could be a useful biomarker in the management of essential hypertensive patients treated with ACE-I or ARB.

  3. Angiotensin-converting enzyme 2-angiotensin (1-7)-Mas axis prevents pancreatic acinar cell inflammatory response via inhibition of the p38 mitogen-activated protein kinase/nuclear factor-κB pathway.

    Science.gov (United States)

    Yu, Xiaozheng; Cui, Lijian; Hou, Fei; Liu, Xiaoya; Wang, Yan; Wen, Yan; Chi, Cheng; Li, Chunyun; Liu, Ruixia; Yin, Chenghong

    2017-11-13

    The aim of the present study was to investigate the role of the angiotensin-converting enzyme (ACE)2-angiotensin‑(Ang)-(1-7)-Mas axis in the pathogenesis of pancreatitis and the association between this axis and the p38 mitogen-activated protein kinase (p38 MAPK)/nuclear factor (NF-κB) signaling pathway in pancreatic acinar cells. Mouse pancreatic acinar cancer (MPC-83) cells were stimulated with 10 nM caerulein (CAE) to create an in vitro model of acute pancreatitis, and collected for analysis at 2, 6, 12, 24 and 48 h post stimulation. In addition, cells were pretreated with different concentrations of Ang‑(1‑7), Ang‑(1‑7) antagonist A779, p38 MAPK inhibitor SB203580 or ACE2 inhibitor DX600 for 30 min, and then stimulated with CAE for 24 h. The ACE2, Mas receptor, p38 MAPK, phosphorylated (p)-p38 MAPK and NF-κB expression levels were evaluated using western blotting and immunofluorescence. p38 MAPK, NF-κB, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-8 and IL-10 mRNA expression levels were assessed using reverse transcription-quantitative polymerase chain reaction. The results of the immunofluorescence assay demonstrated that ACE2 and p38 MAPK were present mainly in the cytoplasm, while the Mas receptor was located mainly in the cell membrane. ACE2, p38 MAPK and p-p38 MAPK protein levels were significantly increased (PMas receptor protein levels were significantly upregulated (PMas axis significantly inhibits pancreatitis by inhibition of the p38 MAPK/NF-κB signaling pathway.

  4. Clustering of cycloidal wave energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Stefan G.

    2016-03-29

    A wave energy conversion system uses a pair of wave energy converters (WECs) on respective active mountings on a floating platform, so that the separation of the WECs from each other or from a central WEC can be actively adjusted according to the wavelength of incident waves. The adjustable separation facilitates operation of the system to cancel reactive forces, which may be generated during wave energy conversion. Modules on which such pairs of WECs are mounted can be assembled with one or more central WECs to form large clusters in which reactive forces and torques can be made to cancel. WECs of different sizes can be employed to facilitate cancelation of reactive forces and torques.

  5. 12 CFR 1.6 - Convertible securities.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option of...

  6. Convertible Subspaces of Hessenberg-Type Matrices

    Directory of Open Access Journals (Sweden)

    Henrique F. da Cruz

    2017-12-01

    Full Text Available We describe subspaces of generalized Hessenberg matrices where the determinant is convertible into the permanent by affixing ± signs. An explicit characterization of convertible Hessenberg-type matrices is presented. We conclude that convertible matrices with the maximum number of nonzero entries can be reduced to a basic set.

  7. Ecologically Optimal Solution of Power Semiconductors Converters

    Directory of Open Access Journals (Sweden)

    Pavol Spanik

    2003-01-01

    Full Text Available One of the relevant scientific programs of Department of Power Electrical Systems is research of ecologically optimal topologies main circuits of power converters. This paper presents some methods how to reduce unfavourable influences of power converters on the grid. The achieved results were applieed in praxis, especially in the power converters produced by Electrotechnical Research and Projecting Institute in Nova Dubnica.

  8. A novel converter topology for TEM applications

    Indian Academy of Sciences (India)

    and energy levels of the TEM system, require special type of excitation technique. Power converters for ... This paper proposes a novel converter topology to meet these excitation current require- ments. A novel ... The converter control system is given a square wave current reference of required amplitude,. ON duration TS ...

  9. Power electronic converters modeling and control with case studies

    CERN Document Server

    Bacha, Seddik; Bratcu, Antoneta Iuliana

    2014-01-01

    Modern power electronic converters are involved in a very broad spectrum of applications: switched-mode power supplies, electrical-machine-motion-control, active power filters, distributed power generation, flexible AC transmission systems, renewable energy conversion systems and vehicular technology, among them. Power Electronics Converters Modeling and Control teaches the reader how to analyze and model the behavior of converters and so to improve their design and control. Dealing with a set of confirmed algorithms specifically developed for use with power converters, this text is in two parts: models and control methods. The first is a detailed exposition of the most usual power converter models: ·        switched and averaged models; ·        small/large-signal models; and ·        time/frequency models. The second focuses on three groups of control methods: ·        linear control approaches normally associated with power converters; ·        resonant controllers b...

  10. Hybrid thermionic-photovoltaic converter

    Science.gov (United States)

    Datas, A.

    2016-04-01

    A conceptual device for the direct conversion of heat into electricity is presented. This concept hybridizes thermionic (TI) and thermophotovoltaic (TPV) energy conversion in a single thermionic-photovoltaic (TIPV) solid-state device. This device transforms into electricity both the electron and photon fluxes emitted by an incandescent surface. This letter presents an idealized analysis of this device in order to determine its theoretical potential. According to this analysis, the key advantage of this converter, with respect to either TPV or TI, is the higher power density in an extended temperature range. For low temperatures, TIPV performs like TPV due to the negligible electron flux. On the contrary, for high temperatures, TIPV performs like TI due to the great enhancement of the electron flux, which overshadows the photon flux contribution. At the intermediate temperatures, ˜1650 K in the case of this particular study, I show that the power density potential of TIPV converter is twice as great as that of TPV and TI. The greatest impact concerns applications in which the temperature varies in a relatively wide range, for which averaged power density enhancement above 500% is attainable.

  11. Hybrid thermionic-photovoltaic converter

    Energy Technology Data Exchange (ETDEWEB)

    Datas, A. [Instituto de Energía Solar, Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2016-04-04

    A conceptual device for the direct conversion of heat into electricity is presented. This concept hybridizes thermionic (TI) and thermophotovoltaic (TPV) energy conversion in a single thermionic-photovoltaic (TIPV) solid-state device. This device transforms into electricity both the electron and photon fluxes emitted by an incandescent surface. This letter presents an idealized analysis of this device in order to determine its theoretical potential. According to this analysis, the key advantage of this converter, with respect to either TPV or TI, is the higher power density in an extended temperature range. For low temperatures, TIPV performs like TPV due to the negligible electron flux. On the contrary, for high temperatures, TIPV performs like TI due to the great enhancement of the electron flux, which overshadows the photon flux contribution. At the intermediate temperatures, ∼1650 K in the case of this particular study, I show that the power density potential of TIPV converter is twice as great as that of TPV and TI. The greatest impact concerns applications in which the temperature varies in a relatively wide range, for which averaged power density enhancement above 500% is attainable.

  12. CCLIBS: The CERN Power Converter Control Libraries

    CERN Document Server

    AUTHOR|(SzGeCERN)404953; Lebioda, Krzysztof Tomasz; Magrans De Abril, Marc; Martino, Michele; Murillo Garcia, Raul; Nicoletti, Achille

    2015-01-01

    Accurate control of power converters is a vital activity in large physics projects. Several different control scenarios may coexist, including regulation of a circuit’s voltage, current, or field strength within a magnet. Depending on the type of facility, a circuit’s reference value may be changed asynchronously or synchronously with other circuits. Synchronous changes may be on demand or under the control of a cyclic timing system. In other cases, the reference may be calculated in real-time by an outer regulation loop of some other quantity, such as the tune of the beam in a synchrotron. The power stage may be unipolar or bipolar in voltage and current. If it is unipolar in current, it may be used with a polarity switch. Depending on the design, the power stage may be controlled by a firing angle or PWM duty-cycle reference, or a voltage or current reference. All these cases are supported by the CERN Converter Control Libraries (CCLIBS). These open-source C libraries include advanced reference generati...

  13. RISK ANALYSIS FOR SHIP CONVERTING PROJECT ACCOMPLISHMENT (Case study of KRI KP Converting Project

    Directory of Open Access Journals (Sweden)

    Dimas Endro W

    2013-10-01

    Full Text Available Ship converting has become as prospective activity in ship building area. Operational and economical aspect are the most dominant rationale. Baseon a new fuction of converted ship, a task list which contain several jobs that must be done is listed. This accomplishment schedule not only contain a task list, but also duration for certain job title. In practical apllication job duration is maintained based on experience of project manager.  Further more, total accomplish duration is setted as time accomplishment for the project. This setted time has become reference for the project bid. Occasionaly, if accomplishment time which offered is strict, than schedule slip become as potencial nightmare. For this situation, project manager has had a cristal clearconsideration to select a proper decision wheter he will take the tender offer or not. practically, project mananger has layed on his experience to handle previous project and face  penalty if the project delayed. This paper focussed on how to measure tender offer based on risk analysis, specially for converted ship tender which has a strike time accomplishment.A new application method to analysis proposed tender based on time and penalty parameter has become a topic of this paper.

  14. Digital control of a high-voltage (2.5 kV) bidirectional DC-DC converter for driving a dielectric electro active polymer (DEAP) based capacitive actuator

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2014-01-01

    . The incremental actuator requires three highvoltage (~2.5 kV) bidirectional DC-DC converters, toaccomplish the incremental motion by charging anddischarging the capacitive actuators. The bidirectional flybackconverter employs a digital controller to improve efficiencyand charge/discharge speed using the valley...

  15. Converting pest insects into food

    DEFF Research Database (Denmark)

    Offenberg, Hans Joachim; Wiwatwittaya, Decha

    2010-01-01

    Canopy dwelling weaver ants (Oecophylla spp.) are used to control a variety of pests in a number of tropical tree crops. What is less familiar is the existence of commercial markets where these ants and their brood are sold for (i) human consumption, (ii) pet food or (iii) traditional medicine...... on management, 32-115 kg ant brood (mainly new queens) was harvested per ha per year without detrimental effect on colony survival and worker ant densities. This suggest that ant biocontrol and ant harvest can be sustainable integrated in plantations and double benefits derived. As ant production is fuelled...... by pest insects, problematic pests are converted into food and additional earnings. To assess the profitability of providing additional food for the ants, O. smaragdina food conversion efficiency (ECI) was estimated in the laboratory. This estimate suggests the feeding of weaver ants in ant farms...

  16. High-Performance Data Converters

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    in a standard CMOS technology, they can be designed to yield 100 dB performance at 10 times oversampling. The proposed scaled-element mismatch-shaping D/A converters are well suited for use as the feedback stage in oversampled delta-sigma quantizers. It is, however, not easy to make full use of their potential...... this problem. This way, the delta-sigma quantizer's feedback signal is obtained by a multiple-stage quantization, where the loop quantizer (low-resolution and minimum-delay) implements only the last-stage quantization. Hence, high-speed, high-resolutiondelta-sigma quantization is feasible without using complex...... circuitry. An improved version of the MASH topology is also proposed. A delta-sigma quantizer is used to quantize the input signal into an oversampled digital representation of low-to-moderate resolution. The delta-sigma quantizer'struncation error is estimated either directly, or as the first...

  17. Reliability of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon

    There are many different working principles for wave energy converters (WECs) which are used to produce electricity from waves. In order for WECs to become successful and more competitive to other renewable electricity sources, the consideration of the structural reliability of WECs is essential...... WEPTOS. Calibration of safety factors are performed for welded structures at theWavestar device including different control systems for harvesting energy from waves. In addition, a case study of different O&M strategies for WECs is discussed, and an example of reliability-based structural optimization....... Structural reliability considerations and optimizations impact operation and maintenance (O&M) costs as well as the initial investment costs. Furthermore, there is a control system for WEC applications which defines the harvested energy but also the loads onto the structure. Therefore, extreme loads but also...

  18. Reliability of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon

    There are many different working principles for wave energy converters (WECs) which are used to produce electricity from waves. In order for WECs tobecome successful and more competitive to other renewable electricity sources,the consideration of the structural reliability of WECs is essential...... for welded structures at the Wavestar device includingdifferent control systems for harvesting energy from waves. In addition, a casestudy of different O&M strategies for WECs is discussed, and an example ofreliability-based structural optimization of the Wavestar foundation ispresented. The work performed.......Structural reliability considerations and optimizations impact operation andmaintenance (O&M) costs as well as the initial investment costs.Furthermore, there is a control system for WEC applications which defines theharvested energy but also the loads onto the structure. Therefore, extremeloads but also fatigue loads...

  19. The SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Kofoed, Jens Peter

    2012-01-01

    The Sea-wave Slot-cone Generator concept (SSG) is a Wave Energy Converter based on the wave overtopping principle utilizing several reservoirs placed on top of each other, in which the energy of the incoming wave will be stored as potential energy. The water captured in the reservoirs will then run...... through turbines for electricity production. The system utilizes a wide spectrum of different wave conditions by means of multiple reservoirs, located at different levels above the still water level. Thereby, it obtains a high overall efficiency and it can be suitable for shoreline and breakwater...... at the Svaaheia site (Norway), Port of Hanstholm (Denmark) and Port of Garibaldi (Oregon, USA). In the last-mentioned two projects, the Sea-wave Slot-cone Generator technology is integrated into outer harbor breakwater and jetty reconstruction projects. Comprehensive studies have been performed in the last years...

  20. Generators for gearless wind energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Grauers, A. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    This paper discusses some design alternatives for directly driven generators, and one specific generator type is investigated for a wide range of rated power. First, the specification for a directly driven generator is presented, then different design alternatives are discussed. A radial-flux permanent magnet generator for frequency converter connection has been chosen for a more detailed investigation. The design, optimization and performance of that generator type are presented. Generators from 30 kW to 3 MW are designed and compared with conventional four-pole generators with gear. It is found that a directly driven generator can be more efficient than a conventional generator and gear and have a rather small diameter and a low active weight. 8 refs, 7 figs, 2 tabs

  1. Combined upregulation of matrix metalloproteinase-1 and proteinase-activated receptor-1 predicts unfavorable prognosis in human nasopharyngeal carcinoma

    Directory of Open Access Journals (Sweden)

    Yang R

    2013-08-01

    Full Text Available Rui Yang,1 Yu Xu,2 Peizhong Li,2 Xin Zhang,2 Junying Wang,2 Dongsheng Gu,2 Yao Wang31State Key Laboratory of Cancer Biology, Cell Engineering Research Center and Department of Cell Biology, Department of Clinical Nursing, School of Nursing, The Fourth Military Medical University, Xi'an, People’s Republic of China; 2Department of Otorhinolaryngology, Huai'an First People’s Hospital, Nanjing Medical University, Huai’an, Jiangsu, People’s Republic of China; 3Pharmaceutical Preparation Section, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, Jiangsu, People’s Republic of ChinaBackground: The upregulation of matrix metalloproteinase-1 (MMP-1 has been demonstrated to be correlated with lymph node metastasis of nasopharyngeal carcinoma (NPC, while the activation of protease-activated receptor-1 (PAR-1 mediates proliferation and invasion of NPC cells. The present study investigated the clinical significance of the coexpression of MMP-1 and PAR-1 in NPC patients in determining the prognosis. Methods: Immunohistochemistry was performed to detect the expression of MMP-1 and PAR-1 in tumor tissue samples from 266 NPC patients. Results: Overexpression of MMP-1 and PAR-1 proteins were, respectively, detected in 190 (71.43% and 182 (68.42% of the 266 NPC patients. In addition, the combined MMP-1 and PAR-1 expression was significantly associated with advanced T-stage (P = 0.01, advanced clinical stage (P = 0.002, positive recurrence (P = 0.01, and metastatic status (P = 0.01 of NPC. Moreover, the overall survival in NPC patients with MMP-1 and PAR-1 dual overexpression was significantly shorter than in those with dual low expression (P < 0.001. Furthermore, the multivariate analyses indicated that the combined MMP-1 and PAR-1 overexpression was an independent prognostic factor for overall survival (P = 0.001 in NPC patients, but the upregulation of MMP-1 and PAR-1 alone was, in each case, not an independent prognostic factor for

  2. High Power Density Power Electronic Converters for Large Wind Turbines

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk

    assessments of these specific VSCs so that their power densities and reliabilities are quantitatively determined, which requires extensive utilization of the electro-thermal models of the VSCs under investigation. In this thesis, the three-level neutral-point-clamped VSCs (3L-NPC-VSCs), which are classified...

  3. Three-phase AC-AC power converters based on matrix converter topology matrix-reactance frequency converters concept

    CERN Document Server

    Szczesniak, Pawel

    2013-01-01

    AC voltage frequency changes is one of the most important functions of solid state power converters. The most desirable features in frequency converters are the ability to generate load voltages with arbitrary amplitude and frequency, sinusoidal currents and voltages waveforms; the possibility of providing unity power factor for any load; and, finally, a simple and compact power circuit. Over the past decades, a number of different frequency converter topologies have appeared in the literature, but only the converters with either a voltage or current DC link are commonly used in industrial app

  4. EGCG Inhibits Proliferation, Invasiveness and Tumor Growth by Up-Regulation of Adhesion Molecules, Suppression of Gelatinases Activity, and Induction of Apoptosis in Nasopharyngeal Carcinoma Cells

    Directory of Open Access Journals (Sweden)

    Chih-Yeu Fang

    2015-01-01

    Full Text Available (−-Epigallocatechin-3-gallate (EGCG, a major green tea polyphenol, has been shown to inhibit the proliferation of a variety of tumor cells. Epidemiological studies have shown that drinking green tea can reduce the incidence of nasopharyngeal carcinoma (NPC, yet the underlying mechanism is not well understood. In this study, the inhibitory effect of EGCG was tested on a set of Epstein Barr virus-negative and -positive NPC cell lines. Treatment with EGCG inhibited the proliferation of NPC cells but did not affect the growth of a non-malignant nasopharyngeal cell line, NP460hTert. Moreover, EGCG treated cells had reduced migration and invasive properties. The expression of the cell adhesion molecules E-cadherin and β-catenin was found to be up-regulated by EGCG treatment, while the down-regulation of matrix metalloproteinases (MMP-2 and MMP-9 were found to be mediated by suppression of extracellular signal-regulated kinase (ERK phosphorylation and AP-1 and Sp1 transactivation. Spheroid formation by NPC cells in suspension was significantly inhibited by EGCG. Oral administration of EGCG was capable of suppressing tumor growth in xenografted mice bearing NPC tumors. Treatment with EGCG was found to elevate the expression of p53 and p21, and eventually led to apoptosis of NPC cells via caspase 3 activation. The nuclear translocation of NF-κB and β-catenin was also suppressed by EGCG treatment. These results indicate that EGCG can inhibit the proliferation and invasiveness, and induce apoptosis, of NPC cells, making it a promising agent for chemoprevention or adjuvant therapy of NPC.

  5. In Vitro angiotensin converting enzyme inhibitory and antioxidant ...

    African Journals Online (AJOL)

    ... present study was carried out to investigate the in vitro angiotensin converting enzyme (ACE) inhibitory and antioxidant activities of the methanolic seed extract of Apium graveolens Linn. belonging to the family Apiaceae. Traditionally, the seeds of A. graveolens L. were used as diuretic, anti-inflammatory and aphrodisiac.

  6. [Familial hyperactivity of angiotensin-converting enzyme (ACE)

    NARCIS (Netherlands)

    Kramers, C.; Adema, G.J.; Korte, M.; Deinum, J.

    2003-01-01

    An extremely high level of serum angiotensin-converting enzyme (ACE) activity was found in eight individuals, women aged 31, 60, 42 and 67 years, and men aged 50, 47, 23 and 50 years. They had consulted a specialist due to a wide range of non-specific complaints or abnormalities (fatigue, dyspnoea,

  7. Angiotensin I-converting enzyme inhibitor derived from cottonseed ...

    African Journals Online (AJOL)

    Six proteolytic enzymes, including alcalase, flavourzyme, trypsin, neutrase, papain and pepsin, were employed to hydrolyze cottonseed protein to produce the hydrolysates of Angiotensin I-converting enzyme (ACE) inhibitory activity. The result indicated that the cottonseed protein hydrolysate (CPH) produced by papain had ...

  8. Effect of partially purified angiotensin converting enzyme inhibitory ...

    African Journals Online (AJOL)

    This study evaluated the effect of partially-purified angiotensin converting enzyme (ACE) inhibitory proteins obtained from the leaves of Moringa oleifera on blood glucose, serum ACE activity and lipid profile of alloxaninduced diabetic rats. Twenty-five apparently healthy male albino rats were divided into five groups of five ...

  9. Power flow controller with a fractionally rated back-to-back converter

    Science.gov (United States)

    Divan, Deepakraj M.; Kandula, Rajendra Prasad; Prasai, Anish

    2016-03-08

    A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

  10. Multilevel converters for 10 MW Wind Turbines

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2011-01-01

    Several promising multi-level converter configurations for 10 MW Wind Turbines both with direct drive and one-stage gear box drive using Permanent Magnet Synchronous Generator (PMSG) are proposed, designed and compared. Reliability is a crucial indicator for large scale wind power converters......, therefore the evaluations are mainly focused on the power device thermal performances, which are closely related to the life time and cost of the converter. Simulation results of different converter candidates regarding the loss and junction temperature are presented and analyzed. It is concluded...... that the three-level and five-level H-bridge converter topologies both have potential to achieve improved thermal performances compared to the three-level Neutral-Point-Clamped converter topology in the wind power application....

  11. Gadolinium sheet converter for neutron radiography

    Energy Technology Data Exchange (ETDEWEB)

    Lima, C.T.S. [Laboratorio de Neutrongrafia em Tempo Real (LNRTR/PEN/COPPE), Universidade Federal do Rio de Janeiro, Ilha do Fundao, Caixa Postal 68509, 21941-972 Rio de Janeiro, RJ (Brazil); Crispim, V.R. [Laboratorio de Neutrongrafia em Tempo Real (LNRTR/PEN/COPPE), Universidade Federal do Rio de Janeiro, Ilha do Fundao, Caixa Postal 68509, 21941-972 Rio de Janeiro, RJ (Brazil); PEN/COPPE-DNC/Escola Politecnica CT, Universidade Federal do Rio de Janeiro, Ilha do Fundao, Caixa Postal 68509, 21941-972 Rio de Janeiro, RJ (Brazil)], E-mail: verginia@con.ufrj.br; Santos, W.M.S. [Laboratorio de Colisao Atomica e Molecular (LACAM/IF), Universidade Federal do Rio de Janeiro, Ilha do Fundao, Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil)

    2007-12-15

    This work describes a methodology developed for the confection of gadolinium sheet converter for neutron radiography using the gadolinium chloride (GdCl{sub 3}) as material converter. Though manufactured at a relatively low cost, they are as good as the sheet converter on the market. Here, we present neutron radiography of the penetrameter, the edge spread function, the modulation transfer function and characteristic curves for each set sheet-AA400 Kodak film.

  12. Ocean floor mounting of wave energy converters

    Science.gov (United States)

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  13. Electro-thermal Modeling for Junction Temperature Cycling-Based Lifetime Prediction of a Press-Pack IGBT 3L-NPC-VSC Applied to Large Wind Turbines

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Munk-Nielsen, Stig; Teodorescu, Remus

    2011-01-01

    Reliability is a critical criterion for multi-MW wind turbines, which are being employed with increasing numbers in wind power plants, since they operate under harsh conditions and have high maintenance cost due to their remote locations. In this study, the wind turbine grid-side converter...... prediction, the converter electro-thermal model including electrical, power loss, and dynamical thermal models is developed with the main focus on the thermal modeling regarding converter topology, switch technology, and physical structure. Moreover, these models are simplified for their practical...... implementation in computation platforms. Finally, the converter lifetimes for wind power profiles are predicted using the IGBT lifetime model available. Hence, the developed electrothermal model’s suitability for the lifetime predictions is shown....

  14. Multipurpose Power Converter for Non-Grid-Connected Microsystems

    Science.gov (United States)

    Vovos, Panagis N.; Georgakas, Konstantinos G.

    2015-04-01

    The aim of this paper is to present a multipurpose converter, appropriate for non-grid-connected microsystems, which are prone to harmonic distortion. The converter suppresses harmonics by injecting mirror harmonics in the modulation stage. An important property is that it continuously monitors and significantly reduces the harmonic content without the use of active or passive low-frequency filters. This is under constant switching frequency, no matter if the harmonics are mainly created by the source, the loads or even its own operation. The converter is regulating output voltage using typical fuzzy control. The two types of control (harmonic and voltage) do not seem to affect each other during operation. Furthermore, it can supply either dc or ac loads from a dc source. The versatility of the converter is a useful property for remote or mobile micropower systems, where neither sources nor loads are of a single type. The converter has been tested successfully for a combination of harmonic-injecting electric appliances and various load step changes.

  15. Commutation Processes in Multiresonant ZVS Bridge Converter

    Directory of Open Access Journals (Sweden)

    Miroslaw Luft

    2008-01-01

    Full Text Available The analysis of the multiresonant ZVS DC/DC bridge converter is presented. The control system of the converter is basedon the method of frequency control at the constant time of transistor turn-off with a phase shift. The operation of the circuit is givenand the operating range of the converter is defined where ZVS switching operation is assured. Control characteristics are given andthe converter’s efficiency is defined. The circuit’s operation is analysed on the basis of results of the converter simulation tests using Simplorer programme.

  16. Conducted Emission Evaluation for Direct Matrix Converters

    Science.gov (United States)

    Nothofer, A.; Tarisciotti, L.; Greedy, S.; Empringham, L.; De Lillo, L.; Degano, M.

    2016-05-01

    Matrix converters have been recently proposed as an alternative solution to the standard back-to-back converter in aerospace applications. However, Electromagnetic Interference (EMI), in particular, conducted emissions represent a critical aspect for this converter family. Direct Matrix Converter (DMC) are usually modelled only at the normal operating frequency, but for the research presented in this paper, the model is modified in order to include a detailed high frequency description, which is of interest for conducted emission studies.This paper analyzes the performance of DMC, when different control and modulation techniques are used. Experimental results are shown to validate the simulation models.

  17. Power Control at Grid Connected Converters and Analytical Solution of Steady States

    OpenAIRE

    Viktor Valouch; Jiří Škramlík; Zdeněk Muller; Jan Švec; Josef Tlustý

    2015-01-01

    The paper presents a power control technique at grid connected converters under unbalanced voltage conditions. The current positive and negative sequences during grid voltage sags are controlled to ensure a proper exchange of active and reactive powers without power ripples. An analytical solution in a closed form of the B6 and B4 converters working with an optimized half a period switching symmetry is presented. The analytical solution may be applied for the converters connected to highly un...

  18. Back-to-back converter control of grid-connected wind turbine to mitigate voltage drop caused by faults

    DEFF Research Database (Denmark)

    Hassanzadeh, Fattah; Sangrody, Hossein; Hajizadeh, Amin

    2017-01-01

    side converter is designed to improve voltage drop caused by the fault in the grid while maximum available active power of wind turbine system is injected to the grid and the DC link voltage in the converter is regulated. The methodology of the converter control is elaborated in details and its...

  19. Production of N-13 labeled compounds with high specific activity

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Kazutoshi; Sasaki, Motoji; Yoshida, Yuichiro; Haradahira, Terushi; Inoue, Osamu [National Inst. of Radiological Sciences, Chiba (Japan)

    1997-03-01

    Nitrogen-13 was produced by irradiating ultra pure water saturated with a pure gas (N2, O2, He, H2) with 18 MeV protons. Ion species generated by irradiation were analyzed with radio ion chromatography systems. An automated equipment was developed to synthesize anhydrous (13N)NH3 as a synthetic precursor and (13N)p-nitrophenyl carbamate ((13N)NPC) as a model compound, using the (13N)NH3. The radiochemical yield and specific activity of (13N)NPC was high enough to carry out the receptor study with PET. (author)

  20. Dosimetric difference amongst 3 techniques: TomoTherapy, sliding-window intensity-modulated radiotherapy (IMRT), and RapidArc radiotherapy in the treatment of late-stage nasopharyngeal carcinoma (NPC).

    Science.gov (United States)

    Lee, Francis Kar-ho; Yip, Celia Wai-yi; Cheung, Frankie Chun-hung; Leung, Alex Kwok-cheung; Chau, Ricky Ming-chun; Ngan, Roger Kai-cheong

    2014-01-01

    To investigate the dosimetric difference amongst TomoTherapy, sliding-window intensity-modulated radiotherapy (IMRT), and RapidArc radiotherapy in the treatment of late-stage nasopharyngeal carcinoma (NPC). Ten patients with late-stage (Stage III or IV) NPC treated with TomoTherapy or IMRT were selected for the study. Treatment plans with these 3 techniques were devised according to departmental protocol. Dosimetric parameters for organ at risk and treatment targets were compared between TomoTherapy and IMRT, TomoTherapy and RapidArc, and IMRT and RapidArc. Comparison amongst the techniques was done by statistical tests on the dosimetric parameters, total monitor unit (MU), and expected delivery time. All 3 techniques achieved similar target dose coverage. TomoTherapy achieved significantly lower doses in lens and mandible amongst the techniques. It also achieved significantly better dose conformity to the treatment targets. RapidArc achieved significantly lower dose to the eye and normal tissue, lower total MU, and less delivery time. The dosimetric advantages of the 3 techniques were identified in the treatment of late-stage NPC. This may serve as a guideline for selection of the proper technique for different clinical cases. © 2013 American Association of Medical Dosimetrists Published by American Association of Medical Dosimetrists All rights reserved.

  1. Modeling and Simulation of Matrix Converter

    DEFF Research Database (Denmark)

    Liu, Fu-rong; Klumpner, Christian; Blaabjerg, Frede

    2005-01-01

    This paper discusses the modeling and simulation of matrix converter. Two models of matrix converter are presented: one is based on indirect space vector modulation and the other is based on power balance equation. The basis of these two models is• given and the process on modeling is introduced...

  2. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    The main aims of power electronic converter systems (PECS) are to control, convert, and condition electrical power flow from one form to another through the use of solid-state electronics. This book outlines current research into the scientific modeling, experimentation, and remedial measures for...

  3. Time-Interleaved Analog to Digital Converters

    NARCIS (Netherlands)

    Louwsma, S.M.; van Tuijl, Adrianus Johannes Maria; Nauta, Bram

    2010-01-01

    This book describes the research carried out by our PhD student Simon Louwsma at the University of Twente, The Netherlands in the field of high-speed Analogto- Digital (AD) converters. AD converters are crucial circuits for modern systems where information is stored or processed in digital form. Due

  4. Synchronous Control of Modular Multilevel Converters

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede; Bose, Bimal K.

    2002-01-01

    for each module and the composed voltage at the output of the converter. Multilevel output voltage of the converter has quarter-wave symmetry during the whole range including the zone of overmodulation. Both continuous and discontinuous versions of synchronous PWM, based on vector approach...

  5. High Precision Current Measurement for Power Converters

    CERN Document Server

    Cerqueira Bastos, M

    2015-01-01

    The accurate measurement of power converter currents is essential to controlling and delivering stable and repeatable currents to magnets in particle accelerators. This paper reviews the most commonly used devices for the measurement of power converter currents and discusses test and calibration methods.

  6. RF digital-to-analog converter

    Science.gov (United States)

    Conway, P.H.; Yu, D.U.L.

    1995-02-28

    A digital-to-analog converter is disclosed for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration. 18 figs.

  7. Modelling and Control of Grid converter

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Iov, Florin

    The present report describes the work done in the Phase 1a during the research project "Modelling and Control of Grid Converter". The developed models for the plant and different control strategies for the grid converter are presented in detail. Simulation results under different operating...

  8. Modelling and Control of Grid converter

    DEFF Research Database (Denmark)

    Iov, Florin; Teodorescu, Remus; Blaabjerg, Frede

    The present report describes the work done in the Phase 1b during the research project "Modelling and Control of Grid Converter". The models used in simulations are presented in detail. Two control strategies for the grid converter are considered for investigations, namely the Adaptive Band...

  9. Present trends in HVDC converter station design

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Lennart; Asplund, Gunnar; Bjorklund, Hans; Flisberg, Gunnar [ABB Power Systems AB, Ludvika (Sweden)

    1994-12-31

    HVDC converter station technology has developed rapidly to satisfy increasing requirements during past 10 - 15 years, but there has not been any dramatic changes since thyristor valves were introduced in the mid 70s. This paper describes some recent and expected future developments, that will substantiality change and simplify future converter stations. (author) 4 refs., 7 figs.

  10. Step-Up DC-DC converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam P.; Gorji, Saman A.

    2017-01-01

    on the general law and framework of the development of next-generation step-up dc-dc converters, this paper aims to comprehensively review and classify various step-up dc-dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage...

  11. An epidemiological and molecular study of the relationship between smoking, risk of nasopharyngeal carcinoma, and Epstein-Barr virus activation.

    Science.gov (United States)

    Xu, Feng-Hua; Xiong, Dan; Xu, Ya-Fei; Cao, Su-Mei; Xue, Wen-Qiong; Qin, Hai-De; Liu, Wen-Sheng; Cao, Jing-Yan; Zhang, Ying; Feng, Qi-Sheng; Chen, Li-Zhen; Li, Man-Zhi; Liu, Zhi-Wei; Liu, Qing; Hong, Ming-Huang; Shugart, Yin Yao; Zeng, Yi-Xin; Zeng, Mu-Sheng; Jia, Wei-Hua

    2012-09-19

    Elevated levels of antibodies against antigens in the Epstein-Barr virus (EBV) lytic phase are important predictive markers for nasopharyngeal carcinoma (NPC) risk. Several lifestyle factors, including smoking, have also been associated with NPC risk. We hypothesized that some specific lifestyle factors induce transformation of EBV from the latent to the lytic stage and contribute to NPC occurrence. We conducted a case-control study using data from male case patients (n = 1316) and control subjects (n = 1571) living in Guangdong Province, an area in China at high risk for NPC, to study potential NPC risk factors and EBV inducers. Two independent healthy male populations from a second high-risk area (n = 1657) and a low-risk area (n = 1961) were also included in the analysis of potential EBV inducers using logistic regression models. In vitro assays were performed to investigate the effect of cigarette smoke extract on EBV activation in two EBV-positive cell lines. All statistical tests were two-sided. Smoking was associated with an increased risk of NPC among the Guangdong participants with 20-40 and 40 or more pack-years vs never smokers (OR = 1.52, 95% CI = 1.22 to 1.88 and OR = 1.76, 95% CI = 1.34 to 2.32, respectively; P (trend) gp350 in the lytic phase. Smoking is not only associated with NPC risk in individuals from China but is also associated with EBV seropositivity in healthy males and is involved in EBV activation.

  12. A Novel Single Switch Transformerless Quadratic DC/DC Buck-Boost Converter

    DEFF Research Database (Denmark)

    Mostaan, Ali; A. Gorji, Saman; N. Soltani, Mohsen

    2017-01-01

    A novel quadratic buck-boost DC/DC converter is presented in this study. The proposed converter utilizes only one active switch and can step-up/down the input voltage, while the existing single switch quadratic buck/boost converters can only work in step-up or step-down mode. First, the proposed...... converter is analyzed in steady-state. Then, its performance is validated using simulations in MATLAB/SIMULINK software. Finally, an experimental prototype is built for further verification....

  13. Transformer Isolated Buck-Boost Converters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2016-12-01

    Full Text Available Of the single-switch dc-to-dc converters, those with the buck-boost voltage transfer function offer most potential for transformer coupling, hence isolation, at the kilowatt level. This paper highlights the limitations of the traditional magnetic coupled, buck-boost topology. Then four split-capacitor transformer-coupled topologies (specifically the Cuk, sepic, zeta, and a new, converters with a common ac equivalent circuit are explored, that do not temporarily store core magnetic energy as does the traditional isolated buck-boost converter nor have a core dc magnetizing current bias, as with the sepic and zeta transformer coupled topologies. Core dc bias capacitive voltage compensation is a practical design constraint in three of the four topologies, while all four must cater for stray and leakage inductance effects. Simulations and experimental results for the new converter at 408W support the transformer-coupled, single-switch dc-to-dc converter concepts investigated.

  14. Modelling, analyses and design of switching converters

    Science.gov (United States)

    Cuk, S. M.; Middlebrook, R. D.

    1978-01-01

    A state-space averaging method for modelling switching dc-to-dc converters for both continuous and discontinuous conduction mode is developed. In each case the starting point is the unified state-space representation, and the end result is a complete linear circuit model, for each conduction mode, which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small-signal). While the method is generally applicable to any switching converter, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The insights that emerge from the general state-space modelling approach lead to the design of new converter topologies through the study of generic properties of the cascade connection of basic buck and boost converters.

  15. Periodic Control of Power Electronic Converters

    DEFF Research Database (Denmark)

    Zhou, Keliang; Danwei, Wang; Yang, Yongheng

    Advanced power electronic converters convert, control and condition electricity. Power converters require control strategies for periodic signal compensation to assure good power quality and stable power system operation. This comprehensive text presents the most recent internal model principle...... based periodic control technology, which offers the perfect periodic control solution for power electronic conversion. It also provides complete analysis and synthesis methods for periodic control systems, and plenty of practical examples to demonstrate the validity of proposed periodic control...... technology for power converters. It proposes a unified framework for housing periodic control schemes for power converters, and provides a general proportional-integral-derivative control solution to periodic signal compensation in extensive engineering applications. Periodic Control of Power Electronic...

  16. A review of Indirect Matrix Converter Topologies

    Directory of Open Access Journals (Sweden)

    Salem Rahmani

    2015-08-01

    Full Text Available Abstract—Matrix Converter (MC is a modern direct AC/AC electrical power converter without dc-link capacitor. MC is operated in four quadrant, assuring a control of the output voltage, amplitude and frequency. The matrix converter has recently attracted significant attention among researchers and it has become increasing attractive for applications of wind energy conversion, military power supplies, induction motor drives, etc. Recently, different MC topologies have been proposed and developed which have their own advantages and disadvantages. Matrix converter can be classified as direct and indirect structures. The direct one has been elaborated in previous work. In this paper the indirect MCs are reviewed. Different characteristics of the indirect MC topologies are mentioned to show the strengths and weaknesses of such converter topologies.

  17. Switched Mode Four-Quadrant Converters

    CERN Document Server

    Thurel, Y

    2015-01-01

    This paper was originally presented at CAS-2004, and was slightly modified for CAS-2014. It presents a review of the key parameters that impact the design choices for a true four-quadrant power converter, in the range 1-10 kW, mainly based on switching mode converter topology. This paper will first describe the state-of-the-art for this power converter family, giving the drawbacks and advantages of different possible solutions. It will also present practical results obtained from the CERN-designed converter. It will finally give some important tips regarding critical phases like test one, when conducting a project dealing with this type of power converter.

  18. CAS - CERN Accelerator School and CLRC Daresbury Laboratory : Specialised CAS Course on Power Converters

    CERN Document Server

    CAS - CERN Accelerator School : Intermediate Accelerator Physics

    2006-01-01

    These proceedings contain the lectures given at the eighteenth specialized course organized by the CERN Accelerator School (CAS), the topic being ‘Power Converters for Particle Accelerators’. The course was held in Warrington, UK, from 12 to 18 May 2004. A similar course took place in Montreux, Switzerland in 1990, with proceedings published as CERN 90-07. After an interval of fourteen years, the aim of this course was to present a review of the actual state of the art and highlight the latest developments in the field. The course started with a basic recapitulation on accelerators, the required performance for the power converters, and the classification of converter topologies. Following this introductory section, more detailed aspects of active and passive components, converter topology analysis and simulations were presented. Based on these building blocks, the main power converter topologies were covered such as thyristor rectifiers, 1-quadrant and 4-quadrant switched-mode power converters. The impor...

  19. Modular Multilevel Converter solutions with few Sub-Modules for wind power application

    DEFF Research Database (Denmark)

    Smirnova, Liudmila; Pyrhönen, Juha; Ma, Ke

    2014-01-01

    Modular Multilevel Converter (MMC) is a topology where series connection of Sub-Modules (SM) is used to achieve almost sinusoidal output voltage. The MMC converter with a large number of SMs is actively used in high voltage DC (HVDC) transmission systems where a bulky converter is not a difficult...... issue. In this paper the possibility to use a MMC with just a few SMs for wind power application with limited space in the nacelle is analysed. The current loading, electrical losses and thermal performance of the power devices in the converter solutions studied are analysed. It is shown that an MMC...... converter with full-bridge (FB) SMs has a more uniform loss and temperature distribution among the semiconductor devices than an MMC with half-bridge (HB) SMs. The reliability of the MMC converters is also investigated in terms of thermal loading....

  20. single-phase dc phase dc-ac boost converter ac boost converter

    African Journals Online (AJOL)

    User

    This paper describes a new power conversion circuit dc-dc boost converter. It boost converter. It boost converter. It comprises an H comprises an H. Change of load .... A full-wave rectified signal is used to produce an AC reference voltage v* o. The outer voltage loop generates the reference current command i* f. A common.

  1. Flexible operation of parallel grid-connecting converters under unbalanced grid voltage

    DEFF Research Database (Denmark)

    Lu, Jinghang; Savaghebi, Mehdi; Guerrero, Josep M.

    2017-01-01

    According to the European grid code, grid-connecting converters should always be connected to the grid under grid voltage unbalance. However, grid voltage unbalance severely affects the stable operation of the converters and leads to the various power issues, such as active power oscillation, DC......-link voltage ripple, and overloading. Moreover, under grid voltage unbalance, the active power delivery ability is decreased due to the converter's current rating limitation. In this paper, a thorough study on the current limitation of the grid-connecting converter under grid voltage unbalance is conducted....... In addition, based on the principle that total output active power should be oscillation free, a coordinated control strategy is proposed for the parallel grid-connecting converters. The case study has been conducted to demonstrate the effectiveness of this proposed control strategy....

  2. Electromagnetic Compatibility of Matrix Converter System

    Directory of Open Access Journals (Sweden)

    S. Fligl

    2006-12-01

    Full Text Available The presented paper deals with matrix converters pulse width modulation strategies design with emphasis on the electromagnetic compatibility. Matrix converters provide an all-silicon solution to the problem of converting AC power from one frequency to another, offering almost all the features required of an ideal static frequency changer. They possess many advantages compared to the conventional voltage or current source inverters. A matrix converter does not require energy storage components as a bulky capacitor or an inductance in the DC-link, and enables the bi-directional power flow between the power supply and load. The most of the contemporary modulation strategies are able to provide practically sinusoidal waveforms of the input and output currents with negligible low order harmonics, and to control the input displacement factor. The perspective of matrix converters regarding EMC in comparison with other types of converters is brightly evident because it is no need to use any equipment for power factor correction and current and voltage harmonics reduction. Such converter with proper control is properly compatible both with the supply mains and with the supplied load. A special digital control system was developed for the realized experimental test bed which makes it possible to achieve greater throughput of the digital control system and its variability.

  3. Underwater noise from a wave energy converter

    DEFF Research Database (Denmark)

    Tougaard, Jakob

    A recent addition to the anthropogenic sources of underwater noise is offshore wave energy converters. Underwater noise was recorded from the Wavestar wave energy converter located at Hastholm, Denmark (57°7.73´N, 8°37.23´E). The Wavestar is a full-scale test and demonstration converter...... in full operation and start and stop of the converter. Median broad band (10 Hz – 20 kHz) sound pressure level (Leq) was 123 dB re. 1 Pa, irrespective of status of the wave energy converter (stopped, running or starting/stopping). The most pronounced peak in the third-octave spectrum was in the 160 Hz...... significant noise above ambient could be detected above the 250 Hz band. The absolute increase in noise above ambient was very small. L50 third-octave levels in the four bands with the converter running were thus only 1-2 dB above ambient L50 levels. The noise recorded 25 m from the wave energy converter...

  4. Selective harmonic control for power converters

    DEFF Research Database (Denmark)

    Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede

    2014-01-01

    This paper proposes an Internal Model Principle (IMP) based Selective Harmonic Controller (SHC) for power converters. The proposed SHC offers an optimal control solution for power converters to mitigate power harmonics. It makes a good trade-off among cost, complexity and performance. It has high...... accuracy and fast transient response, and it is cost-effective, easy for real-time implementation, and compatible for design rules-of-thumb. An application on a three-phase PWM converter has confirmed the effectiveness of the proposed control scheme in terms of harmonic mitigation....

  5. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power......-tolerant adjustable speed drive systems; mission profile oriented reliability design in wind turbine and photovoltaic systems; reliability of power conversion systems in photovoltaic applications; power supplies for computers; and high-power converters. Reliability of Power Electronic Converter Systems is essential...... reading for researchers, professionals and students working with power electronics and their applications, particularly those specializing in the development and application of power electronic converters and systems....

  6. A Discrete Modeling Approach for Buck Converter

    Science.gov (United States)

    Zhaoxia, Leng; Qingfeng, Liu; Jinkun, Sun; Huamin, Wang

    In this paper, a discrete modeling approach for Buck converters based on continuous condition mode (CCM) and discontinuous condition mode (DCM) was presented. The unified coefficient matrixes of discrete model were described by building a mathematical function and the calculation methods of the parameters in coefficient matrixes were given. The working states of Buck converter on various work conditions were described adopting one discrete equation. The validity of the proposed modeling approach was proved by contrasting the output of discrete model with the operation result of Buck converter system in Simulink.

  7. High-power converters and AC drives

    CERN Document Server

    Wu, Bin

    2017-01-01

    This new edition reflects the recent technological advancements in the MV drive industry, such as advanced multilevel converters and drive configurations. It includes three new chapters, Control of Synchronous Motor Drives, Transformerless MV Drives, and Matrix Converter Fed Drives. In addition, there are extensively revised chapters on Multilevel Voltage Source Inverters and Voltage Source Inverter-Fed Drives. This book includes a systematic analysis on a variety of high-power multilevel converters, illustrates important concepts with simulations and experiments, introduces various megawatt drives produced by world leading drive manufacturers, and addresses practical problems and their mitigations methods.

  8. Pseudolog Digital-to-Analog Converter

    Science.gov (United States)

    Gooder, S. T.

    1986-01-01

    Sensitivity decreases by 10 at beginning of each input decade. Method conceived to convert binary-coded data to suitable linear form for stripchart recording. Strip-chart recordings obtained from typical pressure readings in a vacuum system during pumpdown. In reading curve, BCD digital vacuum-gage output processed by analog-to-digital converter in such way that only reading digits (but not range) appear in output. In range and reading, range also converted to analog and placed as most significant digit.

  9. Programmable Analog-To-Digital Converter

    Science.gov (United States)

    Kist, Edward H., Jr.

    1993-01-01

    High-speed analog-to-digital converter with programmable voltage steps that can be changed during operation. Allows concentration of converter resolution over specific portion of waveform. Particularly useful in digitizing wind-shear radar and lidar return signals, in digital oscilloscopes, and other applications in which desirable to increase digital resolution over specific area of waveform while accepting lower resolution over rest of waveform. Effective increase in dynamic range achieved without increase in number of analog-to-digital converter bits. Enabling faster analog-to-digital conversion.

  10. Heatsink Design of High Power Converter

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Ki [Chungang University (Korea)

    1999-04-01

    Various ways of designing heat sink are available for commercial high power converters and among them, the method of air cooling is the most popular and practical method than any other ones. In this paper, a practical method of cooling high power converter, which includes a method of reducing noise and vibration caused by the fan and a method of estimating the gap and contact resistances existing between the thyristor and heat sink, is presented. Finally, the heat transfer analysis and implementation methods of heat sink for high power converter is presented. (author). 14 refs., 11 figs., 3 tabs.

  11. Power Electronics Converters for Wind Turbine Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Liserre, Marco; Ma, Ke

    2012-01-01

    The steady growth of installed wind power together with the upscaling of the single wind turbine power capability has pushed the research and development of power converters toward full-scale power conversion, lowered cost pr kW, increased power density, and also the need for higher reliability......, in the latter case with attention to series connection and parallel connection either electrical or magnetic ones (multiphase/windings machines/transformers). It is concluded that as the power level increases in wind turbines, medium-voltage power converters will be a dominant power converter configuration...

  12. multilevel buck converter for automotive electrical load

    African Journals Online (AJOL)

    user

    MULTILEVEL BUCK CONVERTER FOR AUTOMOTIVE ELECTRICAL LOAD. E. T. Yabefa1,* and D. Ebregbe2. 1ELECTRICAL DEPARTMENT, BAYELSA STATE COLLEGE OF ARTS & SCIENCE (BYCAS) YENAGOA, BAYELSA STATE NIGERIA. 2ELECTRICAL ENGINEERING DEPARTMENT, NIGER DELTA UNIVERSITY, ...

  13. Reliability of power electronic converter systems

    CERN Document Server

    Chung, Henry Shu-hung; Blaabjerg, Frede; Pecht, Michael

    2016-01-01

    This book outlines current research into the scientific modeling, experimentation, and remedial measures for advancing the reliability, availability, system robustness, and maintainability of Power Electronic Converter Systems (PECS) at different levels of complexity.

  14. State estimation for wave energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Bacelli, Giorgio; Coe, Ryan Geoffrey

    2017-04-01

    This report gives a brief discussion and examples on the topic of state estimation for wave energy converters (WECs). These methods are intended for use to enable real-time closed loop control of WECs.

  15. Load balancing multimodule switching power converters

    Science.gov (United States)

    Mclyman, W. T.; Wester, G. W.

    1979-01-01

    Regulating system individually adjusts duty cycles of modules so that all share load equally, thus, protects individual modules and their components from overload and increases reliability and life expectancy. Converters are alternative to high-power, single unit systems.

  16. A three-port direct current converter

    DEFF Research Database (Denmark)

    2016-01-01

    The three-port direct current converter comprising: at least one input direct current source; at least one storage battery; a primary side circuit; a secondary side circuit; a first single magnetic component shared by the primary side circuit and the secondary side circuit, wherein the primary side...... circuit comprises a connection between the at least one input direct current source and the at least one storage battery, the primary side circuit configured for operating as a buck converter; a second magnetic component serially coupled to the first single magnetic component, wherein the first and second...... magnetic components are configured to perform a voltage step-up, wherein the secondary side circuit comprises a connection between the at least one storage battery and at least one load, the secondary side configured for operating as a tapped boost converter; wherein the three-port direct current converter...

  17. Catalytic converters as a source of platinum

    Directory of Open Access Journals (Sweden)

    A. Fornalczyk

    2011-10-01

    Full Text Available The increase of Platinum Group Metals demand in automotive industry is connected with growing amount of cars equipped with the catalytic converters. The paper presents the review of available technologies during recycling process. The possibility of removing platinum from the used catalytic converters applying pyrometallurgical and hyrdometallurgical methods were also investigated. Metals such as Cu, Pb, Ca, Mg, Cd were used in the pyrometallurgical research (catalytic converter was melted with Cu, Pb and Ca or Mg and Cd vapours were blown through the whole carrier. In hydrometallurgical research catalytic converters was dissolved in aqua regia. Analysis of Pt contents in the carrier before and after the process was performed by means of atomic absorption spectroscopy. Obtained result were discussed.

  18. Third order digital-to-analog converter

    Science.gov (United States)

    Dotson, W. P.

    1972-01-01

    System, consisting of sample and hold digital-to-analog converter, clock circuit, sample delay circuit, initial condition circuit and interpolator circuit, improves accuracy of reconstructed analog signal without increasing sample rates.

  19. (PFC) converters feeding brushless DC motor drive

    African Journals Online (AJOL)

    DR OKE

    1Department of Electrical Engineering, Indian Institute of Technology Delhi, INDIA ... configurations of PFC converters feeding BLDC motor drive are presented as low ..... In future, it is expected for a continuing research in the quest of energy ...

  20. Input-output rearrangement of isolated converters

    DEFF Research Database (Denmark)

    Madsen, Mickey Pierre; Kovacevic, Milovan; Mønster, Jakob Døllner

    2015-01-01

    This paper presents a new way of rearranging the input and output of isolated converters. The new arrangement posses several advantages, as increased voltage range, higher power handling capabilities, reduced voltage stress and improved efficiency, for applications where galvanic isolation...

  1. Fast simulation techniques for switching converters

    Science.gov (United States)

    King, Roger J.

    1987-01-01

    Techniques for simulating a switching converter are examined. The state equations for the equivalent circuits, which represent the switching converter, are presented and explained. The uses of the Newton-Raphson iteration, low ripple approximation, half-cycle symmetry, and discrete time equations to compute the interval durations are described. An example is presented in which these methods are illustrated by applying them to a parallel-loaded resonant inverter with three equivalent circuits for its continuous mode of operation.

  2. Solid-state power converter repeatability analysis

    CERN Document Server

    Dal Gobbo, Anthony; Aguglia, Davide

    2015-01-01

    This paper presents a method for evaluating power converter repeatability. The focus is on solid-state switch mode power converter for which the most problematic non-repeatability sources are the jitter of the drivers and of the switches leading to output voltage pulses bad repeatability. Both driver and switch turn-on and turn-off delay dispersion have been measured. These measurements confirm that the delay is Gaussian distributed and that the repeatability prediction method is valid.

  3. Switching power converters medium and high power

    CERN Document Server

    Neacsu, Dorin O

    2013-01-01

    An examination of all of the multidisciplinary aspects of medium- and high-power converter systems, including basic power electronics, digital control and hardware, sensors, analog preprocessing of signals, protection devices and fault management, and pulse-width-modulation (PWM) algorithms, Switching Power Converters: Medium and High Power, Second Edition discusses the actual use of industrial technology and its related subassemblies and components, covering facets of implementation otherwise overlooked by theoretical textbooks. The updated Second Edition contains many new figures, as well as

  4. Utilization of Nonlinear Converters for Audio Amplification

    OpenAIRE

    Iversen, Niels; Birch, Thomas; Knott, Arnold

    2012-01-01

    Class D ampliers ts the automotive demands quite well. The traditional buck-based amplier has reduced both the cost and size of ampliers. However the buck topology is not without its limitations. The maximum peak AC output voltage produced by the power stage is only equal the supply voltage. The introduction ofnon-linear converters for audio amplication defeats this limitation. A Cuk converter, designed to deliver an AC peak output voltage twice the supply voltage, is presented in this paper....

  5. ANALOG-TO-DIGITAL DATA CONVERTER

    Science.gov (United States)

    Rodgers, G.W.; Althouse, J.E.; Anderson, D.P.; Bussey, G.R.; Minnear, L.H.

    1960-09-01

    Electrical apparatus is described, particularly useful in telemetry work, for converting analog signals into electrical pulses and recording them. An electronic editor commands the taking of signal readings at a frequency which varies according to linearity of the analog signal being converted. Readings of information signals are recorded, along with time base readings and serial numbering, if desired, on magnetic tape and the latter may be used to operate a computer or the like. Magnetic tape data may be transferred to punched cards.

  6. Mitigation of EMI in a flyback converter

    OpenAIRE

    2013-01-01

    M.Ing. (Electrical & Electronic Engineering Science) This study investigates the mitigation of conducted electromagnetic interference (EMI) in a flyback DC-DC converter. Without the use of filters, the maximum mitigation of EMI possible without significantly decreasing converter operating efficiency is investigated. The following parameters are found to influence EMI: · Switching speed: Decreasing switching speed (increasing rise and fall times of the MOSFET) effectively reduces both commo...

  7. TOTAL HARMONIC DISTORTION ANALYSIS OF MATRIX CONVERTER

    OpenAIRE

    K. Kandan; Senthilkumar,K.; Dhivya, K.

    2016-01-01

    This paper deals with the validation and design analysis of Matrix converter for variable frequency using mathematical equations. The analysis was done using Venturini modulation algorithm. The PI controller is used for Matrix converter to reduce Total Harmonic Distortion (THD) in the output current. The comparative study is done for open loop and closed loop PI compensation in MATLAB-Simulink. Furthermore, the output waveforms are produced with significant reduction in the Total Harmonic Dis...

  8. Optimal Design of a Push-Pull-Forward Half-Bridge (PPFHB) Bidirectional DC–DC Converter With Variable Input Voltage

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2012-01-01

    This paper presents a low-cost bidirectional isolated dc–dc converte, derived from dual-active-bridge converter for the power sources with variable output voltage like supercapacitors. The proposed converter consists of push-pull-forward circuit half-bridge circuit (PPFHB) and a high-frequency tr......This paper presents a low-cost bidirectional isolated dc–dc converte, derived from dual-active-bridge converter for the power sources with variable output voltage like supercapacitors. The proposed converter consists of push-pull-forward circuit half-bridge circuit (PPFHB) and a high...

  9. LHC Power Converters: A Precision Game

    CERN Multimedia

    2001-01-01

    The LHC test-bed, String 2, is close to commissioning and one important element to get a first chance to prove what it can do is the power converter system. In String 2 there are 16 converters, in the full LHC there will be almost 1800. This article takes a look at what is so special about the power converters for the LHC. The 13 000 Amps power converters with the watercooled cables going to the String 2 feedboxes. The LHC's superconducting magnets will be the pinnacle of high technology. But to work, they'll need the help of high-precision power converters to supply them with extremely stable DC current. Perfection will be the name of the game, with an accuracy of just 1-2 parts per million (ppm) required. LEP, for the sake of comparison, could live with 10-20 ppm. The LHC's power converters will be very different from those of LEP or the SPS since the new accelerator's magnets are mostly superconducting. That means that they require much higher currents at a lower voltage since superconductors have no re...

  10. Adaptive electrothermal protection of power converters

    Directory of Open Access Journals (Sweden)

    Baraniuk G. A.

    2017-06-01

    Full Text Available Thermal management for power converters during normal operation and transient modes when electrical components are warmed up is an actual problem. This can be particularly important for converters with intermittent duty operation, e.g. power supplies for resistance welding. According to some research, nearly 60% of failures are temperature-induced, and for every 10°C temperature rise in operating environment the failure rate nearly doubles. In this paper, thermal motion of state equations eigenvalue is analysed. It is shown, that in semiconductor converters with an output smoothing filter it is appropriate to use thermal protection devices based on thermal normalisation of the converter filter and, while for cases when short circuits are possible it is appropriate to use a soft start system with thermal adaptation for soft start time factor. Based on these results, two systems of thermal protections operating for semiconductor power converters are introduced. Simulation of combined electromagnetic and thermal processes in buck converter operating with both thermal management systems in overlapping environments MATLAB/Simulink and PLECS showed the possibility to significantly reduce thermal shock on semiconductor components. Using the system of filter parameters normalisation decreases the temperature of the crystal from 210°C to 85°C, using the adaptive soft start system decreases the temperature from 180°C to 80°C. The simulation results are confirmed by tests on real devices.

  11. Enhancement of Power Factor Correction Using Dual Boost Converter

    OpenAIRE

    Himanshu Singh; Pratibha Tiwari

    2014-01-01

    This paper aims to develop a circuit for PFC using active filtering approach by implementing two boost converters arranged in parallel. It shall be based on an optimized power sharing strategy to improve the current quality and at the same time reduce the switching losses. The work involves simulation of basic power electronic circuits and the analysis of the current and voltage waveforms. It starts with simple circuits with a gradual increase in complexity by inclusion of new...

  12. AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

    Directory of Open Access Journals (Sweden)

    Rui Li

    2016-12-01

    Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

  13. A Study of A B3R Converter Based PCU, to Confirm the Flexibility and Performance of the Converter Topology

    OpenAIRE

    Mache Erik; Koch Michael

    2017-01-01

    The main objective of this activity was to study the B3R converter [1] and to confirm its flexibility and performance (mainly efficiency and mass reduction) versus solutions that is implemented in a satellite PCU. For details see [2] ESTEC SOW. An architecture with centralised regulated bus, single battery and centralised solar array was selected for this study. Project Plan: - Study, design and development of an evaluation prototype, based on the B3R topology (including protections ...

  14. Interleukin-1β Converting Enzyme–like Protease Involvement in Fas-induced and Activation-induced Peripheral Blood T Cell Apoptosis in HIV Infection. TNF-related Apoptosis-inducing Ligand Can Mediate Activation-induced T Cell Death in HIV Infection

    Science.gov (United States)

    Katsikis, Peter D.; Garcia-Ojeda, Marcos E.; Torres-Roca, Javier F.; Tijoe, Iwan M.; Smith, Craig A.; Herzenberg, Leonore A.; Herzenberg, Leonard A.

    1997-01-01

    Apoptosis of peripheral blood T cells has been suggested to play an important role in the pathogenesis of human immunodeficiency virus (HIV) infection. Spontaneous, Fas (CD95)–induced and activation-induced T cell apoptosis have all been described in peripheral blood mononuclear cell cultures of HIV-infected individuals. We have previously shown that activation-induced T cell apoptosis is Fas independent in peripheral blood T cells from HIV+ individuals. In this study, we extend and confirm these observations by using an inhibitor of interleukin-1β converting enzyme (ICE) homologues. We show that z-VAD-fmk, a tripeptide inhibitor of ICE homologues, can inhibit Fas-induced apoptosis of peripheral blood CD4+ and CD8+ T cells from asymptomatic HIV+ individuals. z-VAD-fmk also inhibited activation (anti-CD3)– induced CD4+ and CD8+ T cell apoptosis (AICD) in some but not all asymptomatic HIV+ individuals. Apoptosis was measured by multiparameter flow cytometry. The z-VAD-fmk inhibitor also enhanced survival of T cells in anti-Fas or anti-CD3 antibody-treated cultures and inhibited DNA fragmentation. AICD that could be inhibited by z-VAD-fmk was Fas independent and could be inhibited with a blocking monoclonal antibody to tumor necrosis factor–related apoptosis-inducing ligand (TRAIL), a recently described member of the TNF/nerve growth factor ligand family. The above findings show that Fas-induced T cell apoptosis is ICE dependent in HIV infection. AICD can be blocked by ICE inhibitors in some patients, and this AICD is mediated by TRAIL. These results show that TRAIL can be a mediator of AICD in T cells. These different mechanisms of peripheral blood T cell apoptosis may play different roles in the pathogenesis of HIV infection. PMID:9334376

  15. Isolated and soft-switched power converter

    Science.gov (United States)

    Peng, Fang Zheng; Adams, Donald Joe

    2002-01-01

    An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

  16. Understanding delta-sigma data converters

    CERN Document Server

    Pavan, Shanti; Temes, Gabor C

    2017-01-01

    This new edition introduces novel analysis and design techniques for delta-sigma (ΔΣ) converters in physical and conceptual terms, and includes new chapters that explore developments in the field over the last decade. This book explains the principles and operation of delta-sigma analog-to-digital converters (ADCs) in physical and conceptual terms in accordance with the most recent developments in the field. The interest of ΔΣ converter designers has shifted significantly over the past decade, due to many new applications for data converters at the far ends of the frequency spectrum. Continuous-time delta-sigma A/D converters with GHz clocks, of both lowpass and bandpass types, are required for wireless applications. At the other extreme, multiplexed ADCs with very narrow (sometimes 10 Hz wide) signal bandwidths, but very high accuracy are needed in the interfaces of biomedical and environmental sensors. To reflect the changing eeds of designers, the second edition includes significant new material on bo...

  17. A resonant dc-dc power converter assembly

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor of the s......The present invention relates to a resonant DC-DC power converter assembly comprising a first resonant DC-DC power converter and a second resonant DC-DC power converter having identical circuit topologies. A first inductor of the first resonant DC-DC power converter and a second inductor...

  18. Current Source Converters in Discontinuous Conduction Modes of Operation

    Science.gov (United States)

    Cuzner, Robert M.

    This work demonstrates that Current Source Rectifier (CSR) pulse-width modulation (PWM) can be successfully modified for discontinuous conduction mode (DCM). DCM is characterized by input current distortion and non-linear input to output voltage ratio. A Dead-Beat Current Injection (DBCI) PWM method is developed that ensures sinusoidal input currents and linear input to output voltage control while in DCM. A method for control analysis is proposed that enables design of the CSR closed loop voltage controller. The proposed method is simulated to show that the desired objectives are achieved at no load and very light load, where the CSR operates in an extreme DCM condition. Experimental results verify performance of the DBCI-PWM method and validate both simulation and analytical tools used to explore the capabilities of the approach. Index Terms---Active buck rectifier, Current source rectifier (CSR), current source PWM rectifier, power conversion, power converter design, power converter analysis, input power quality

  19. Delayed angioedema during therapy with angiotensin-converting enzyme inhibitors

    Directory of Open Access Journals (Sweden)

    Janković Slobodan M.

    2011-01-01

    Full Text Available Introduction. Angiotensin-converting enzyme inhibitors are leading cause of drug-induced angioedema, with incidence of 0.1 to 0.2%. The angioedema is not of immune nature; in predisposed individuals it is caused by accumulation of vasoactive mediators due to reduced activity of angiotensinconverting enzyme. Case report. We presented a 63-year old male patient suffering from hypertension and chronic obstructive pulmonary disease, who had developed two episodes of angioedema during a 5-year long therapy with enalapril. The first episode happened after three, and the second after five years of the therapy. On both occasions, the patient was admitted to the hospital and tracheotomy was avoided in the last moment. Conclusion. Long-term therapy with angiotensin-converting enzyme inhibitors could be associated with delayed angioedema, especially in patients with inflammation of airways caused by infection or chronic irritation.

  20. Converters for Distributed Power Generation Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Yang, Yongheng

    2015-01-01

    Power electronics technology has become the enabling technology for the integration of distributed power generation systems (DPGS) such as offshore wind turbine power systems and commercial photovoltaic power plants. Depending on the applications, a vast array of DPGS-based power converter...... presents an overview of the power converters for the DPGS, mainly based on wind turbine systems and photovoltaic systems, covering a wide range of applications. Moreover, the modulation schemes and interfacing power filters for the power converters are also exemplified. Finally, the general control...... topologies has been developed and more are coming into the market in order to achieve an efficient and reliable power conversion from the renewables. In addition, stringent demands from both the distribution system operators and the consumers have been imposed on the renewable-based DPGS. This article...

  1. Self-oscillating resonant power converter

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to resonant power converters and inverters comprising a self-oscillating feedback loop coupled from a switch output to a control input of a switching network comprising one or more semiconductor switches. The self-oscillating feedback loop sets a switching frequency...... of the power converter and comprises a first intrinsic switch capacitance coupled between a switch output and a control input of the switching network and a first inductor. The first inductor is coupled in-between a first bias voltage source and the control input of the switching network and has...... a substantially fixed inductance. The first bias voltage source is configured to generate an adjustable bias voltage applied to the first inductor. The output voltage of the power converter is controlled in a flexible and rapid manner by controlling the adjustable bias voltage....

  2. Metamaterial polarization converter analysis: limits of performance

    DEFF Research Database (Denmark)

    Markovich, Dmitry L.; Andryieuski, Andrei; Zalkovskij, Maksim

    2013-01-01

    In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed...... level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50 %, while the realistic reflection configuration can give the conversion efficiency up to 90 %. We show that a double layer transmission converter...... and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design...

  3. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power...... electronic converter systems; anomaly detection and remaining-life prediction for power electronics; reliability of DC-link capacitors in power electronic converters; reliability of power electronics packaging; modeling for life-time prediction of power semiconductor modules; minimization of DC......-link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault...

  4. High Efficiency Reversible Fuel Cell Power Converter

    DEFF Research Database (Denmark)

    Pittini, Riccardo

    The large scale integration of renewable energy sources requires suitable energy storage systems to balance energy production and demand in the electrical grid. Bidirectional fuel cells are an attractive technology for energy storage systems due to the high energy density of fuel. Compared...... to traditional unidirectional fuel cell, bidirectional fuel cells have increased operating voltage and current ranges. These characteristics increase the stresses on dc-dc and dc-ac converters in the electrical system, which require proper design and advanced optimization. This work is part of the PhD project...... entitled "High Efficiency Reversible Fuel Cell Power Converter" and it presents the design of a high efficiency dc-dc converter developed and optimized for bidirectional fuel cell applications. First, a brief overview of fuel cell and energy storage technologies is presented. Different system topologies...

  5. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    -link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault......The main aims of power electronic converter systems (PECS) are to control, convert, and condition electrical power flow from one form to another through the use of solid-state electronics. This book outlines current research into the scientific modeling, experimentation, and remedial measures...... for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power...

  6. Reliability of Power Electronic Converter Systems

    DEFF Research Database (Denmark)

    The main aims of power electronic converter systems (PECS) are to control, convert, and condition electrical power flow from one form to another through the use of solid-state electronics. This book outlines current research into the scientific modeling, experimentation, and remedial measures...... for advancing the reliability, availability, system robustness, and maintainability of PECS at different levels of complexity. Drawing on the experience of an international team of experts, this book explores the reliability of PECS covering topics including an introduction to reliability engineering in power......-link capacitance in power electronic converter systems; wind turbine systems; smart control strategies for improved reliability of power electronics system; lifetime modelling; power module lifetime test and state monitoring; tools for performance and reliability analysis of power electronics systems; fault...

  7. THE PREPARATION AND FUNCTION OF THE HYPERTENSIN-CONVERTING ENZYME

    Science.gov (United States)

    Skeggs, Leonard T.; Kahn, Joseph R.; Shumway, Norman P.

    1956-01-01

    It has been shown by use of isolated, perfused rat kidneys that hypertensin II is a potent vasoconstrictor substance while hypertensin I is not. Hence it would appear that in intact animals the pressor activity of hypertensin I results from its rapid conversion to hypertensin II. An enzyme which effects this conversion has been procured from horse plasma in a semipurified form by means of ammonium sulfate fractionation and isoelectric precipitation. A method is described for estimating the activity of the enzyme. An example of the use of the preparation in converting purified hypertensin I to hypertensin II has been described. PMID:13295487

  8. Impedance coordinative control for cascaded converter in bidirectional application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Loh, Poh Chiang; Deng, Fujin

    2016-01-01

    A two-stage cascaded converter is formed by connecting two sub-converters in series. Output impedance of one sub-converter will therefore interact with input impedance of the other sub-converter. Such interaction may affect the system dynamics and stability, especially when one sub-converter is c......A two-stage cascaded converter is formed by connecting two sub-converters in series. Output impedance of one sub-converter will therefore interact with input impedance of the other sub-converter. Such interaction may affect the system dynamics and stability, especially when one sub......-converter is constant-power-controlled, and hence has different impedance characteristics when its power reverses. To lessen such constant-power effects, a control scheme that can coordinate impedance behaviors of the two sub-converters is proposed. The idea is to reshape the lowfrequency negative impedance...

  9. Hydrodynamic Performance of a Wave Energy Converter

    Science.gov (United States)

    Yang, Yingchen

    2010-11-01

    To harvest energy from ocean waves, a new wave energy converter (WEC) was proposed and tested in a wave tank. The WEC freely floats on the water surface and rides waves. It utilizes its wave-driven angular oscillation to convert the mechanical energy of waves into electricity. To gain the maximum possible angular oscillation of the WEC under specified wave conditions, both floatation of the WEC and wave interaction with the WEC play critical roles in a joint fashion. During the experiments, the submersion condition of the WEC and wave condition were varied. The results were analyzed in terms of the oscillation amplitude, stability, auto-orientation capability, and wave frequency dependency.

  10. The Angiotensin-Converting-Enzyme-Induced Angioedema.

    Science.gov (United States)

    Bas, Murat

    2017-02-01

    The bradykinin B2 receptor antagonist icatibant is effective in angiotensin-converting enzyme inhibitor-induced angioedema. The drug is not approved officially for this indication and has to be administered in an emergency situation off-label. Corticosteroids or antihistamines do not seem to work in this condition. The effectiveness of C1-esterase-inhibitor in angiotensin-converting enzyme-induced angioedema must be verified in a double-blind study. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Generalized modular multilevel converter and modulation

    DEFF Research Database (Denmark)

    Liu, Hui; Loh, Poh Chiang; Blaabjerg, Frede

    2014-01-01

    Modular multilevel converter (MMC) has gained popularity recently with its modulation, capacitor voltage balancing and circulating current issues widely discussed. Contributing to this effort, a study is presented here to show how the MMC topology can be derived from the viewpoint of two series...... converters regulating a power grid. The generalized topology derived and notated as GMMC can then be altered to create various types of MMC, including the traditional topology that is presently well-known. This effort has not been previously discussed, and may smoothen the understanding of MMC operation...

  12. Soft switched DC-DC converter

    Science.gov (United States)

    Subramanian, K.; Kavitha, K. V. N.; Saravanan, K.

    2017-11-01

    A soft switched single switch isolated dc-dc conveys proposed in this paper. This converter works on the principle of zero current switching (zcs) and zero voltage switching (zvs). The circuit comprises lossless snubber with low rating. The switch works on zcs during turn on and zvs during turnoff. The diodes are based on zcs turn on and turnoff conditions. This paper presents the concept of soft switching and its applications to dc-dc converter. The losses due to soft switching and hard switching are compared.

  13. Combination solar photovoltaic heat engine energy converter

    Science.gov (United States)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  14. A quadratic analog-to-digital converter

    Science.gov (United States)

    Harrison, D. C.; Staples, M. H.

    1980-01-01

    An analog-to-digital converter with a square root transfer function has been developed for use with a pair of CCD imaging detectors in the White Light Coronagraph/X-ray XUV Telescope experiment to be flown as part of the Internal Solar Polar Mission. It is shown that in background-noise-limited instrumentation systems a quadratic analog-to-digital converter will allow a maximum dynamic range with a fixed number of data bits. Low power dissipation, moderately fast conversion time, and reliability are achieved in the proposed design using standard components and avoiding nonlinear elements.

  15. Electrodes For Alkali-Metal Thermoelectric Converters

    Science.gov (United States)

    Williams, Roger M.; Wheeler, Bob L.; Jeffries-Nakamura, Barbara; Lamb, James L.; Bankston, C. Perry; Cole, Terry

    1989-01-01

    Combination of thin, porous electrode and overlying collector grid reduces internal resistance of alkali-metal thermoelectric converter cell. Low resistance of new electrode and grid boosts power density nearly to 1 W/cm2 of electrode area at typical operating temperatures of 1,000 to 1,300 K. Conductive grid encircles electrode film on alumina tube. Bus wire runs along tube to collect electrical current from grid. Such converters used to transform solar, nuclear, and waste heat into electric power.

  16. Converting ODM Metadata to FHIR Questionnaire Resources.

    Science.gov (United States)

    Doods, Justin; Neuhaus, Philipp; Dugas, Martin

    2016-01-01

    Interoperability between systems and data sharing between domains is becoming more and more important. The portal medical-data-models.org offers more than 5.300 UMLS annotated forms in CDISC ODM format in order to support interoperability, but several additional export formats are available. CDISC's ODM and HL7's framework FHIR Questionnaire resource were analyzed, a mapping between elements created and a converter implemented. The developed converter was integrated into the portal with FHIR Questionnaire XML or JSON download options. New FHIR applications can now use this large library of forms.

  17. IGBT Based DC/DC Converter

    Directory of Open Access Journals (Sweden)

    M. Akherraz

    1997-12-01

    Full Text Available This paper presents an in-depth analytical and experimental investigation of an indirect DC-DC converter. The DC-AC conversion is a full bridge based on IGBT power modules, and the AC-DC conversion is done via a high  frequency AC link and a first diode bridge. The AC link, which consists of snubbing capacitors and a variable air-gap transformer, is analytically designed to fulfill Zero Voltage commutation requirement. The proposed converter is simulated using PSPICE and a prototype is designed built and tested in the laboratory. PSPICE simulation and experimental results are presented and compared.

  18. Efficient modelling of a modular multilevel converter

    DEFF Research Database (Denmark)

    El-Khatib, Walid Ziad; Holbøll, Joachim; Rasmussen, Tonny Wederberg

    2013-01-01

    Looking at the near future, we see that offshore wind penetration into the electrical grid will continue increasing rapidly. Until very recently, the trend has been to place the offshore wind farms close to shore within the reach for transmission using HVAC cables but for larger distances HVDC...... are calculated for the converter. Time-domain simulations on a MMC HVDC test system are performed in the PSCAD/EMTDC software environment based on the new model. The results demonstrate that the modeled MMC-HVDC system with or without converter transformer is able to operate under specific fault conditions....

  19. Opposing Gatekeepers of Apical Sterol Transport: Niemann-Pick C1-Like 1 (NPC1L1) and ATP-Binding Cassette Transporters G5 and G8 (ABCG5/ABCG8)

    Science.gov (United States)

    Brown, J. Mark; Yu, Liqing

    2010-01-01

    Cholesterol is essential for the growth and function of all mammalian cells, but abnormally elevated levels of circulating low-density lipoprotein cholesterol (LDL-C) are a major risk factor for the development of atherosclerotic cardiovascular disease (ASCVD). For many years, statin drugs have been used to effectively lower LDL-C, but ASCVD still persists in most of the world. Hence, additional LDL-C lowering is now recommended, and the search for therapeutic strategies that work in synergy with statins has now begun. Intestinal absorption and biliary excretion of cholesterol represent two major pathways and continue to show promise as druggable processes. Importantly, both of these complex physiological pathways are tightly regulated by key proteins located at the apical surface of the small intestine and the liver. One of these proteins, the target of ezetimibe Niemann-Pick C1-Like 1 (NPC1L1), was recently identified to be essential for intestinal cholesterol absorption and protect against excessive biliary sterol loss. In direct opposition of NPC1L1, the heterodimer of ATP-binding cassette transporters G5 and G8 (ABCG5/ABCG8) has been shown to be critical for promoting biliary cholesterol secretion in the liver, and has also been proposed to play a direct role in intestinal disposal of sterols. The purpose of this review is to summarize the current state of knowledge regarding the function of these opposing apical cholesterol transporters, and provide a framework for future studies examining these proteins. PMID:20174593

  20. Efficient, lightweight dc/dc switching converter

    Science.gov (United States)

    Cuk, S.; Middlebrook, R. D.

    1981-01-01

    Converters have input properties of boost power stage and output properties of buck power stage, yet they perform general conversion function with high efficiency. Other features include non-pulsating input/output currents, use of capacitive energy transfer, low output voltage ripple, reduced EMI, and small size.