The NPC: A Higher Priority for Networking Policy

Science.gov (United States)

Kuhns, Jeff C.

2006-01-01

This article discusses the scope of activities of the Network Policy Council (NPC), which has been designed to provide a more direct channel of communications within EDUCAUSE and to provide policy formulation more visibility. The NPC is an advisory council to EDUCAUSE whose members are selected from those who have interest in this area and are…

Expression patterns of sterol transporters NPC1 and NPC2 in the cnidarian-dinoflagellate symbiosis.

Science.gov (United States)

Dani, Vincent; Priouzeau, Fabrice; Mertz, Marjolijn; Mondin, Magali; Pagnotta, Sophie; Lacas-Gervais, Sandra; Davy, Simon K; Sabourault, Cécile

2017-10-01

The symbiotic interaction between cnidarians (e.g., corals and sea anemones) and photosynthetic dinoflagellates of the genus Symbiodinium is triggered by both host-symbiont recognition processes and metabolic exchange between the 2 partners. The molecular communication is crucial for homeostatic regulation of the symbiosis, both under normal conditions and during stresses that further lead to symbiosis collapse. It is therefore important to identify and fully characterise the key players of this intimate interaction at the symbiotic interface. In this study, we determined the cellular and subcellular localization and expression of the sterol-trafficking Niemann-Pick type C proteins (NPC1 and NPC2) in the symbiotic sea anemones Anemonia viridis and Aiptasia sp. We first established that NPC1 is localised within vesicles in host tissues and to the symbiosome membranes in several anthozoan species. We demonstrated that the canonical NPC2-a protein is mainly expressed in the epidermis, whereas the NPC2-d protein is closely associated with symbiosome membranes. Furthermore, we showed that the expression of the NPC2-d protein is correlated with symbiont presence in healthy symbiotic specimens. As npc2-d is a cnidarian-specific duplicated gene, we hypothesised that it probably arose from a subfunctionalisation process that might result in a gain of function and symbiosis adaptation in anthozoans. Niemann-Pick type C proteins may be key players in a functional symbiosis and be useful tools to study host-symbiont interactions in the anthozoan-dinoflagellate association. © 2017 John Wiley & Sons Ltd.

Analysis of a Multilevel Dual Active Bridge (ML-DAB DC-DC Converter Using Symmetric Modulation

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M. A. Moonem

2015-04-01

Full Text Available Dual active bridge (DAB converters have been popular in high voltage, low and medium power DC-DC applications, as well as an intermediate high frequency link in solid state transformers. In this paper, a multilevel DAB (ML-DAB has been proposed in which two active bridges produce two-level (2L-5L, 5L-2L and 3L-5L voltage waveforms across the high frequency transformer. The proposed ML-DAB has the advantage of being used in high step-up/down converters, which deal with higher voltages, as compared to conventional two-level DABs. A three-level neutral point diode clamped (NPC topology has been used in the high voltage bridge, which enables the semiconductor switches to be operated within a higher voltage range without the need for cascaded bridges or multiple two-level DAB converters. A symmetric modulation scheme, based on the least number of angular parameters rather than the duty-ratio, has been proposed for a different combination of bridge voltages. This ML-DAB is also suitable for maximum power point tracking (MPPT control in photovoltaic applications. Steady-state analysis of the converter with symmetric phase-shift modulation is presented and verified using simulation and hardware experiments.

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

3L-NPC inverters are more popular due to their superior performance compared with two level inverters. One of the most optimal applications for multilevel inverter is the Adjustable Speed Drives (ASD). The industry reported numerous ASD failures due to high frequency PWM. Those failures consist i...... strategies is to reduce the Common Mode Voltage (CMV) and balance the DC Link Voltage....

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

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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.

Cascaded impedance networks for NPC inverter

DEFF Research Database (Denmark)

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

2010-01-01

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...

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

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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.

Localization and role of NPC1L1 in cholesterol absorption in human intestine.

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Sané, Alain Théophile; Sinnett, Daniel; Delvin, Edgard; Bendayan, Moise; Marcil, Valérie; Ménard, Daniel; Beaulieu, Jean-François; Levy, Emile

2006-10-01

Recent studies have documented the presence of Niemann-Pick C1-Like 1 (NPC1L1) in the small intestine and its capacity to transport cholesterol in mice and rats. The current investigation was undertaken to explore the localization and function of NPC1L1 in human enterocytes. Cell fractionation experiments revealed an NPC1L1 association with apical membrane of the enterocyte in human jejunum. Signal was also detected in lysosomes, endosomes, and mitochondria. Confirmation of cellular NPC1L1 distribution was obtained by immunocytochemistry. Knockdown of NPC1L1 caused a decline in the ability of Caco-2 cells to capture micellar [(14)C]free cholesterol. Furthermore, this NPC1L1 suppression resulted in increased and decreased mRNA levels and activity of HMG-CoA reductase, the rate-limiting step in cholesterol synthesis, and of ACAT, the key enzyme in cholesterol esterification, respectively. An increase was also noted in the transcriptional factor sterol-regulatory element binding protein that modulates cholesterol homeostasis. Efforts were devoted to define the impact of NPC1L1 knockdown on other mediators of cholesterol uptake. RT-PCR evidence is presented to show the significant decrease in the levels of scavenger receptor class B type I (SR-BI) with no changes in ABCA1, ABCG5, and cluster determinant 36 in NPC1L1-deficient Caco-2 cells. Together, our data suggest that NPC1L1 contributes to intestinal cholesterol homeostasis and possibly cooperates with SR-BI to mediate cholesterol absorption in humans.

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...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....

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...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....

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

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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.

Acid sphingomyelinase activity is regulated by membrane lipids and facilitates cholesterol transfer by NPC2.

Science.gov (United States)

Oninla, Vincent O; Breiden, Bernadette; Babalola, Jonathan O; Sandhoff, Konrad

2014-12-01

During endocytosis, membrane components move to intraluminal vesicles of the endolysosomal compartment for digestion. At the late endosomes, cholesterol is sorted out mainly by two sterol-binding proteins, Niemann-Pick protein type C (NPC)1 and NPC2. To study the NPC2-mediated intervesicular cholesterol transfer, we developed a liposomal assay system. (Abdul-Hammed, M., B. Breiden, M. A. Adebayo, J. O. Babalola, G. Schwarzmann, and K. Sandhoff. 2010. Role of endosomal membrane lipids and NPC2 in cholesterol transfer and membrane fusion. J. Lipid Res. 51: 1747-1760.) Anionic lipids stimulate cholesterol transfer between liposomes while SM inhibits it, even in the presence of anionic bis(monoacylglycero)phosphate (BMP). Preincubation of vesicles containing SM with acid sphingomyelinase (ASM) (SM phosphodiesterase, EC 3.1.4.12) results in hydrolysis of SM to ceramide (Cer), which enhances cholesterol transfer. Besides SM, ASM also cleaves liposomal phosphatidylcholine. Anionic phospholipids derived from the plasma membrane (phosphatidylglycerol and phosphatidic acid) stimulate SM and phosphatidylcholine hydrolysis by ASM more effectively than BMP, which is generated during endocytosis. ASM-mediated hydrolysis of liposomal SM was also stimulated by incorporation of diacylglycerol (DAG), Cer, and free fatty acids into the liposomal membranes. Conversely, phosphatidylcholine hydrolysis was inhibited by incorporation of cholesterol, Cer, DAG, monoacylglycerol, and fatty acids. Our data suggest that SM degradation by ASM is required for physiological secretion of cholesterol from the late endosomal compartment, and is a key regulator of endolysosomal lipid digestion. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.

Niemann-pick type C1 (NPC1) overexpression alters cellular cholesterol homeostasis.

Science.gov (United States)

Millard, E E; Srivastava, K; Traub, L M; Schaffer, J E; Ory, D S

2000-12-08

The Niemann-Pick type C1 (NPC1) protein is a key participant in intracellular trafficking of low density lipoprotein cholesterol, but its role in regulation of sterol homeostasis is not well understood. To characterize further the function of NPC1, we generated stable Chinese hamster ovary (CHO) cell lines overexpressing the human NPC1 protein (CHO/NPC1). NPC1 overexpression increases the rate of trafficking of low density lipoprotein cholesterol to the endoplasmic reticulum and the rate of delivery of endosomal cholesterol to the plasma membrane (PM). CHO/NPC1 cells exhibit a 1.5-fold increase in total cellular cholesterol and up to a 2.9-fold increase in PM cholesterol. This increase in PM cholesterol is closely paralleled by a 3-fold increase in de novo cholesterol synthesis. Inhibition of cholesterol synthesis results in marked redistribution of PM cholesterol to intracellular sites, suggesting an unsuspected role for NPC1 in internalization of PM cholesterol. Despite elevated total cellular cholesterol, CHO/NPC1 cells exhibit increased cholesterol synthesis, which may be attributable to both resistance to oxysterol suppression of sterol-regulated gene expression and to reduced endoplasmic reticulum cholesterol levels under basal conditions. Taken together, these studies provide important new insights into the role of NPC1 in the determination of the levels and distribution of cellular cholesterol.

Application of Simplified Neutral Point Clamped Multilevel Converter in a Small Wind Turbine

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Mlodzikowski Pawel

2014-05-01

Full Text Available In low power distributed generation systems low cost together with the energy quality requirements are a key element. It is known that quality of voltage waveforms generated from multilevel converters is better in comparison with those from two-level. Due to advancements in power electronics and microcontrollers, multilevel converters are being built with the use of integrated power modules thus this type of converters are getting more compact in size. This paper investigates performance of a derivation from the most popular multilevel topology - a neutral point clamped converter (NPC. Applying the idea for simplifying the topology by reducing the number of switches (what came from drives this NPC converter is capable of bidirectional AC/DC/AC operation. For the AC/DC part two schemes are tested: Direct Torque Control Space Vector Modulated and Field Oriented Control but for the DC/AC part a control scheme utilizing the proportional-resonant controller was chosen. Laboratory setup was based on a permanent magnet synchronous generator with control and acquisition completed with the help of dSpace 1005 control box. Experimental verification shows that system operates properly.

A new Zero Voltage Switching three-level NPC inverter

DEFF Research Database (Denmark)

He, Ning; Chen, Yenan; Xu, Dehong

2015-01-01

A novel Zero Voltage Switching (ZVS) three-level NPC inverter topology using a new ZVS Space Vector Modulation (SVM) scheme is proposed. A detailed operation analysis of ZVS three-level NPC inverter is given. The ZVS condition of the proposed ZVS inverter is derived and it can be achieved of all...

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......, with the proposed modulation methods, the thermal distribution in the 3L-NPC wind power inverter undergoing LVRT becomes more equal, and the junction temperature of the most stressed devices can be also relieved. Also, the control ability of the dc-bus NP potential, which is one of the crucial considerations...

Modular Multilevel Converters Based Variable Speed Wind Turbines for Grid Faults

DEFF Research Database (Denmark)

Deng, Fujin; Liu, Dong; Wang, Yanbo

2016-01-01

in the dc-link of the power converter to improve system performance, but also ensure the grid-side current balancing to increase the generated power of the wind turbine under the unbalanced grid fault, in comparison with the conventional VSWT based on BTB three-level NPC converters. The simulation studies......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...

Multilevel-clamped multilevel converters (MLC²)

DEFF Research Database (Denmark)

Rodriguez, Pedro; Bellar, Maria Dias; Muñoz-Aguliar, Raúl Santiago

2012-01-01

clamping scheme is the ML clamping cell, which is composed of a pair of dc sources associated with one single-pole/triple-throw type of switch arrangement. The number of series-connected ML-clamping cells will set the number of levels of the synthesized waveform. By depending on the MCU arrangements......, different converter configurations can be derived, namely, the common clamping and the modular types. Both approaches can be accomplished by employing classical three-level neutral-point-clamped (NPC) technology. Thus, the overall structure of the resultant converter is kept simple, wherein the number...

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.

Structure of N-Terminal Domain of NPC1 Reveals Distinct Subdomains for Binding and Transfer of Cholesterol

Energy Technology Data Exchange (ETDEWEB)

Kwon, Hyock Joo; Abi-Mosleh, Lina; Wang, Michael L.; Deisenhofer, Johann; Goldstein, Joseph L.; Brown, Michael S.; Infante, Rodney E.; (UTSMC)

2010-09-21

LDL delivers cholesterol to lysosomes by receptor-mediated endocytosis. Exit of cholesterol from lysosomes requires two proteins, membrane-bound Niemann-Pick C1 (NPC1) and soluble NPC2. NPC2 binds cholesterol with its isooctyl side chain buried and its 3{beta}-hydroxyl exposed. Here, we describe high-resolution structures of the N-terminal domain (NTD) of NPC1 and complexes with cholesterol and 25-hydroxycholesterol. NPC1(NTD) binds cholesterol in an orientation opposite to NPC2: 3{beta}-hydroxyl buried and isooctyl side chain exposed. Cholesterol transfer from NPC2 to NPC1(NTD) requires reorientation of a helical subdomain in NPC1(NTD), enlarging the opening for cholesterol entry. NPC1 with point mutations in this subdomain (distinct from the binding subdomain) cannot accept cholesterol from NPC2 and cannot restore cholesterol exit from lysosomes in NPC1-deficient cells. We propose a working model wherein after lysosomal hydrolysis of LDL-cholesteryl esters, cholesterol binds NPC2, which transfers it to NPC1(NTD), reversing its orientation and allowing insertion of its isooctyl side chain into the outer lysosomal membranes.

Triazoles inhibit cholesterol export from lysosomes by binding to NPC1.

Science.gov (United States)

Trinh, Michael N; Lu, Feiran; Li, Xiaochun; Das, Akash; Liang, Qiren; De Brabander, Jef K; Brown, Michael S; Goldstein, Joseph L

2017-01-03

Niemann-Pick C1 (NPC1), a membrane protein of lysosomes, is required for the export of cholesterol derived from receptor-mediated endocytosis of LDL. Lysosomal cholesterol export is reportedly inhibited by itraconazole, a triazole that is used as an antifungal drug [Xu et al. (2010) Proc Natl Acad Sci USA 107:4764-4769]. Here we show that posaconazole, another triazole, also blocks cholesterol export from lysosomes. We prepared P-X, a photoactivatable cross-linking derivative of posaconazole. P-X cross-linked to NPC1 when added to intact cells. Cross-linking was inhibited by itraconazole but not by ketoconazole, an imidazole that does not block cholesterol export. Cross-linking of P-X was also blocked by U18666A, a compound that has been shown to bind to NPC1 and inhibit cholesterol export. P-X also cross-linked to purified NPC1 that was incorporated into lipid bilayer nanodiscs. In this in vitro system, cross-linking of P-X was inhibited by itraconazole, but not by U18666A. P-X cross-linking was not prevented by deletion of the N-terminal domain of NPC1, which contains the initial binding site for cholesterol. In contrast, P-X cross-linking was reduced when NPC1 contained a point mutation (P691S) in its putative sterol-sensing domain. We hypothesize that the sterol-sensing domain has a binding site that can accommodate structurally different ligands.

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

inverters, but also reduces the switching loss of the inverter along with an inherent neutral point (NP) voltage control. Based on a circuit-level decoupling concept, the NPC inverter can be decoupled into two three-level Buck converters in every defined operating section, and thereby the controller design...... can be reduced by one third. In order to explain the operation of this topology properly, the decoupling principle including the driving signal synthesis and the NP potential variation are analyzed in detail in this paper. Finally the viability and performance of the proposed modulation scheme...

Structural Insights into the Niemann-Pick C1 (NPC1)-Mediated Cholesterol Transfer and Ebola Infection.

Science.gov (United States)

Gong, Xin; Qian, Hongwu; Zhou, Xinhui; Wu, Jianping; Wan, Tao; Cao, Pingping; Huang, Weiyun; Zhao, Xin; Wang, Xudong; Wang, Peiyi; Shi, Yi; Gao, George F; Zhou, Qiang; Yan, Nieng

2016-06-02

Niemann-Pick disease type C (NPC) is associated with mutations in NPC1 and NPC2, whose gene products are key players in the endosomal/lysosomal egress of low-density lipoprotein-derived cholesterol. NPC1 is also the intracellular receptor for Ebola virus (EBOV). Here, we present a 4.4 Å structure of full-length human NPC1 and a low-resolution reconstruction of NPC1 in complex with the cleaved glycoprotein (GPcl) of EBOV, both determined by single-particle electron cryomicroscopy. NPC1 contains 13 transmembrane segments (TMs) and three distinct lumenal domains A (also designated NTD), C, and I. TMs 2-13 exhibit a typical resistance-nodulation-cell division fold, among which TMs 3-7 constitute the sterol-sensing domain conserved in several proteins involved in cholesterol metabolism and signaling. A trimeric EBOV-GPcl binds to one NPC1 monomer through the domain C. Our structural and biochemical characterizations provide an important framework for mechanistic understanding of NPC1-mediated intracellular cholesterol trafficking and Ebola virus infection. Copyright © 2016 Elsevier Inc. All rights reserved.

A new configuration for multilevel converters with diode clamped topology

DEFF Research Database (Denmark)

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

2008-01-01

Due to the increased use of renewable energy and power elctronic applications, more multilevel converters (MLC) are developed. A Neutral Point Clamped (NPC) inverter is one of the most used multilevel topologies for wind turbine (WT) and photovoltaic (PV) applications. One of the most crucial...... of load changes which can avoid neutral point balancing problem in such converters. In addition, the presented topology is suitable for renewable energy systems to boost the low rectified output-voltage. In order to verify the proposed topology, steady state analysis, modelling and simulations are carried...

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

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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.

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.

Operational limits of a three level neutral point clamped converter used for controlling a hybrid energy storage system

International Nuclear Information System (INIS)

Etxeberria, A.; Vechiu, I.; Camblong, H.; Kreckelbergh, S.; Bacha, S.

2014-01-01

Highlights: • The control of a hybrid storage system using a Three Level NPC converter is analysed. • A sinusoidal PWM with an offset injection is used to control the storage system. • The operation of the selected converter is analysed in its entire operation range. • The operational limits of the Three Level NPC converter are defined. - Abstract: This work analyses the use of a Three-Level Neutral Point Clamped (3LNPC) converter to control the power flow of a Hybrid Energy Storage System (HESS) and at the same time interconnect it with the common AC bus of a microgrid. Nowadays there is not any storage technology capable of offering a high energy storage capacity, a high power capacity and a fast response at the same time. Therefore, the necessity of hybridising more than one storage technology is a widely accepted idea in order to satisfy the mentioned requirements. This work shows how the operational limits of the 3LNPC converter can be calculated and integrated in a control structure to facilitate an optimal use of the HESS according to the rules fixed by the user

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

DEFF Research Database (Denmark)

Choi, Uimin; Blaabjerg, Frede

2017-01-01

the power rating and lifetime of the NPC inverter are limited by the most stressed devices. In this paper, an asymmetric power device rating selection method for the NPC inverter is proposed in order to balance the lifetimes of the power devices. The thermal distribution of the power devices is analyzed......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...... based on 30 kW NPC inverter as a case study. Analytical power loss and thermal impedance models depending on the chip size are derived. Finally, using these models, the junction temperatures of the power devices depending on the chip size is discussed and a proper chip size for an even temperature...

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...... 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...... exclusively in the canalicular membrane, where the protein is highly mobile. Our study demonstrates dynamic trafficking of NPC1L1 between cell surface and intracellular compartments and suggests that this transport is involved in NPC1L1 mediated cellular sterol uptake....

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

International Nuclear Information System (INIS)

Fliss-Jaber, Lilia; Houissa-Kastally, Radhia; Bouzouita, Kamel; Khediri, Naceur; Khelifa, Ridha

2004-01-01

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). 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. 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 < 0,0001) than their PBL. On the other hand, patients PBL produced significantly higher levels of IL-2 (p = 0,022), IL-10 (p = 0,016) and IgM (p = 0,004) than those of controls. No significant differences for IL-6 and IgA were observed. 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

Sterol transfer between cyclodextrin and membranes: similar but not identical mechanism to NPC2-mediated cholesterol transfer.

Science.gov (United States)

McCauliff, Leslie A; Xu, Zhi; Storch, Judith

2011-08-30

Niemann--Pick C disease is an inherited disorder in which cholesterol and other lipids accumulate in the late endosomal/lysosomal compartment. Recently, cyclodextrins (CD) have been shown to reduce symptoms and extend lifespan in animal models of the disease. In the present studies we examined the mechanism of sterol transport by CD using in vitro model systems and fluorescence spectroscopy and NPC2-deficient fibroblasts. We demonstrate that cholesterol transport from the lysosomal cholesterol-binding protein NPC2 to CD occurs via aqueous diffusional transfer and is very slow; the rate-limiting step appears to be dissociation of cholesterol from NPC2, suggesting that specific interactions between NPC2 and CD do not occur. In contrast, the transfer rate of the fluorescent cholesterol analogue dehydroergosterol (DHE) from CD to phospholipid membranes is very rapid and is directly proportional to the acceptor membrane concentration, as is DHE transfer from membranes to CD. Moreover, CD dramatically increases the rate of sterol transfer between membranes, with rates that can approach those mediated by NPC2. The results suggest that sterol transfer from CD to membranes occurs by a collisional transfer mechanism involving direct interaction of CD with membranes, similar to that shown previously for NPC2. For CD, however, absolute rates are slower compared to NPC2 for a given concentration, and the lysosomal phospholipid lysobisphosphatidic acid (LBPA) does not stimulate rates of sterol transfer between membranes and CD. As expected from the apparent absence of interaction between CD and NPC2, the addition of CD to NPC2-deficient fibroblasts rapidly rescued the cholesterol accumulation phenotype. Thus, the recent observations of CD efficacy in mouse models of NPC disease are likely the result of CD enhancement of cholesterol transport between membranes, with rapid sterol transfer occurring during CD--membrane interactions.

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...... reliability is investigated regarding IGBT lifetime based on junction temperature cycling for the grid-side press-pack IGBT 3L-NPC-VSC, which is a state-of-the art high reliability solution. In order to acquire IGBT junction temperatures for given wind power profiles and to use them in IGBT lifetime...... 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...

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

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...

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

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...... 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...

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.

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

Science.gov (United States)

2016-09-07

VH-2) is resistant to infection in an NPC1-36   dependent manner . We found that VH-2 cells are resistant to EBOV infection because the Rus-37...infection in a host species-dependent manner (24). Here, we demonstrate that an adjacent 89   residue, 503, highly conserved in the domain C of NPC1...Tyr sequence 194   change at residue 503 might influence EBOV GPCL–NPC1 binding in a bidirectional manner . 195   Accordingly, we expressed and

The GARP Complex Is Involved in Intracellular Cholesterol Transport via Targeting NPC2 to Lysosomes.

Science.gov (United States)

Wei, Jian; Zhang, Ying-Yu; Luo, Jie; Wang, Ju-Qiong; Zhou, Yu-Xia; Miao, Hong-Hua; Shi, Xiong-Jie; Qu, Yu-Xiu; Xu, Jie; Li, Bo-Liang; Song, Bao-Liang

2017-06-27

Proper intracellular cholesterol trafficking is critical for cellular function. Two lysosome-resident proteins, NPC1 and NPC2, mediate the egress of low-density lipoprotein-derived cholesterol from lysosomes. However, other proteins involved in this process remain largely unknown. Through amphotericin B-based selection, we isolated two cholesterol transport-defective cell lines. Subsequent whole-transcriptome-sequencing analysis revealed two cell lines bearing the same mutation in the vacuolar protein sorting 53 (Vps53) gene. Depletion of VPS53 or other subunits of the Golgi-associated retrograde protein (GARP) complex impaired NPC2 sorting to lysosomes and caused cholesterol accumulation. GARP deficiency blocked the retrieval of the cation-independent mannose 6-phosphate receptor (CI-MPR) to the trans-Golgi network. Further, Vps54 mutant mice displayed reduced cellular NPC2 protein levels and increased cholesterol accumulation, underscoring the physiological role of the GARP complex in cholesterol transport. We conclude that the GARP complex contributes to intracellular cholesterol transport by targeting NPC2 to lysosomes in a CI-MPR-dependent manner. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Identification of 58 novel mutations in Niemann-Pick disease type C: correlation with biochemical phenotype and importance of PTC1-like domains in NPC1.

Science.gov (United States)

Park, Walter D; O'Brien, John F; Lundquist, Patrick A; Kraft, Daniel L; Vockley, Cate Walsh; Karnes, Pamela S; Patterson, Marc C; Snow, Karen

2003-10-01

The two known complementation groups of Niemann-Pick Type C disease, NPC1 and NPC2, result from non-allelic protein defects. Both the NPC1 and NPC2 (HE1) gene products are intimately involved in cholesterol and glycolipid trafficking and/or transport. We describe mutation analysis on samples from 143 unrelated affected NPC patients using conformation sensitive gel electrophoresis and DNA sequencing as the primary mutation screening methods for NPC1 and NPC2, respectively. These methods are robust, sensitive, and do not require any specialized laboratory equipment. Analyses identified two NPC1 mutations for 115 (80.4%) patients, one NPC1 mutation for 10 (7.0%) patients, two NPC2 mutations for five (3.5%) patients, one NPC2 mutation for one (0.7%) patient, and no mutations for 12 (8.4%) patients. Thus, mutations were identified on 251 of 286 (88%) disease alleles, including 121 different mutations (114 in NPC1 and seven in NPC2), 58 of which are previously unreported. The most common NPC1 mutation, I1061T, was detected on 18% of NPC alleles. Other NPC1 mutations were mostly private, missense mutations located throughout the gene with clustering in the cysteine-rich luminal domain. Correlation with biochemical data suggests classification of several mutations as severe and others as moderate or variable. The region between amino acids 1038 and 1253, which shares 35% identity with Patched 1, appears to be a hot spot for mutations. Additionally, a high percentage of mutations were located at amino acids identical to the NPC1 homolog, NPC1L1. Biochemical complementation analysis of cases negative for mutations revealed a high percentage of equivocal results where the complementation group appeared to be non-NPC1 and non-NPC2. This raises the possibilities of an additional NPC complementation group(s) or non-specificity of the biochemical testing for NPC. These caveats must be considered when offering mutation testing as a clinical service. Copyright 2003 Wiley-Liss, Inc.

Synthesis and evaluation of radioiodinated NPC 22009, a putative CRF receptor antagonist

International Nuclear Information System (INIS)

Balasubramanian, V.; Hiner, R.N.; Mavunkel, B.J.; Elliott, R.L.; Abreu, M.E.

1992-01-01

Several studies have suggested that corticotropin-releasing factor (CRF) plays a role in stress-related disorders such as anxiety, depression, anorexia nervosa and stress-induced immune suppression. Hence CRF antagonists have potential therapeutic utility. Recently the authors discovered that pyrazolones such as NPC 22009 and the corresponding disulfide behave as CRF antagonists in vitro with micromolar potency. To probe the nature of this CRF antagonism they developed a convenient synthesis of radioiodinated NPC 22009. Details of the synthesis and preliminary pharmacological studies are presented

Concerted regulation of npc2 binding to endosomal/lysosomal membranes by bis(monoacylglycero)phosphate and sphingomyelin

DEFF Research Database (Denmark)

Enkavi, Giray; Mikkolainen, Heikki; Güngör, Burçin

2017-01-01

remained elusive. Here, based on an extensive set of atomistic simulations and free energy calculations, we clarify the mechanism and energetics of npc2-membrane binding and characterize the roles of physiologically relevant key lipids associated with the binding process. Our results capture in atomistic......Niemann-Pick Protein C2 (npc2) is a small soluble protein critical for cholesterol transport within and from the lysosome and the late endosome. Intriguingly, npc2-mediated cholesterol transport has been shown to be modulated by lipids, yet the molecular mechanism of npc2-membrane interactions has......). This mode is associated with cholesterol uptake and release. On the other hand, the second mode (Supine) places the cholesterol binding pocket away from the membrane surface, but has overall higher membrane binding affinity. We determined that bis(monoacylglycero)phosphate (bmp) is specifically required...

Cholesterol accumulation in Niemann Pick type C (NPC) model cells causes a shift in APP localization to lipid rafts

International Nuclear Information System (INIS)

Kosicek, Marko; Malnar, Martina; Goate, Alison; Hecimovic, Silva

2010-01-01

It has been suggested that cholesterol may modulate amyloid-β (Aβ) formation, a causative factor of Alzheimer's disease (AD), by regulating distribution of the three key proteins in the pathogenesis of AD (β-amyloid precursor protein (APP), β-secretase (BACE1) and/or presenilin 1 (PS1)) within lipid rafts. In this work we tested whether cholesterol accumulation upon NPC1 dysfunction, which causes Niemann Pick type C disease (NPC), causes increased partitioning of APP into lipid rafts leading to increased CTF/Aβ formation in these cholesterol-rich membrane microdomains. To test this we used CHO NPC1 -/- cells (NPC cells) and parental CHOwt cells. By sucrose density gradient centrifugation we observed a shift in fl-APP/CTF compartmentalization into lipid raft fractions upon cholesterol accumulation in NPC vs. wt cells. Furthermore, γ-secretase inhibitor treatment significantly increased fl-APP/CTF distribution in raft fractions in NPC vs. wt cells, suggesting that upon cholesterol accumulation in NPC1-null cells increased formation of APP-CTF and its increased processing towards Aβ occurs in lipid rafts. Our results support that cholesterol overload, such as in NPC disease, leads to increased partitioning of APP/CTF into lipid rafts resulting in increased amyloidogenic processing of APP in these cholesterol-rich membranes. This work adds to the mechanism of the cholesterol-effect on APP processing and the pathogenesis of Alzheimer's disease and supports the role of lipid rafts in these processes.

In silico assessment of phosphorylation and O-β-GlcNAcylation sites in human NPC1 protein critical for Ebola virus entry.

Science.gov (United States)

Basharat, Zarrin; Yasmin, Azra

2015-08-01

Ebola is a highly pathogenic enveloped virus responsible for deadly outbreaks of severe hemorrhagic fever. It enters human cells by binding a multifunctional cholesterol transporter Niemann-Pick C1 (NPC1) protein. Post translational modification (PTM) information for NPC1 is crucial to understand Ebola virus (EBOV) entry and action due to changes in phosphorylation or glycosylation at the binding site. It is difficult and costly to experimentally assess this type of interaction, so in silico strategy was employed. Identification of phosphorylation sites, including conserved residues that could be possible targets for 21 predicted kinases was followed by interplay study between phosphorylation and O-β-GlcNAc modification of NPC1. Results revealed that only 4 out of 48 predicted phosphosites exhibited O-β-GlcNAc activity. Predicted outcomes were integrated with residue conservation and 3D structural information. Three Yin Yang sites were located in the α-helix regions and were conserved in studied vertebrate and mammalian species. Only one modification site S425 was found in β-turn region located near the N-terminus of NPC1 and was found to differ in pig, mouse, cobra and humans. The predictions suggest that Yin Yang sites may not be important for virus attachment to NPC1, whereas phosphosite 473 may be important for binding and hence entry of Ebola virus. This information could be useful in addressing further experimental studies and therapeutic strategies targeting PTM events in EBOV entry. Copyright © 2015 Elsevier B.V. All rights reserved.

RNA Export through the NPC in Eukaryotes.

Science.gov (United States)

Okamura, Masumi; Inose, Haruko; Masuda, Seiji

2015-03-20

In eukaryotic cells, RNAs are transcribed in the nucleus and exported to the cytoplasm through the nuclear pore complex. The RNA molecules that are exported from the nucleus into the cytoplasm include messenger RNAs (mRNAs), ribosomal RNAs (rRNAs), transfer RNAs (tRNAs), small nuclear RNAs (snRNAs), micro RNAs (miRNAs), and viral mRNAs. Each RNA is transported by a specific nuclear export receptor. It is believed that most of the mRNAs are exported by Nxf1 (Mex67 in yeast), whereas rRNAs, snRNAs, and a certain subset of mRNAs are exported in a Crm1/Xpo1-dependent manner. tRNAs and miRNAs are exported by Xpot and Xpo5. However, multiple export receptors are involved in the export of some RNAs, such as 60S ribosomal subunit. In addition to these export receptors, some adapter proteins are required to export RNAs. The RNA export system of eukaryotic cells is also used by several types of RNA virus that depend on the machineries of the host cell in the nucleus for replication of their genome, therefore this review describes the RNA export system of two representative viruses. We also discuss the NPC anchoring-dependent mRNA export factors that directly recruit specific genes to the NPC.

Thermal loading and reliability of 10 MW multilevel wind power converter at different wind roughness classes

DEFF Research Database (Denmark)

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

2012-01-01

This paper focuses on the design, thermal loading and reliability of a three-level Neutral Point Clamped (3-L NPC) back-to-back full scale converter for a 10 MW direct-drive wind turbine equipped with a Permanent Magnet Synchronous Generator (PMSG). The reliability performance of the three......-level converter is strongly influenced by the thermal behaviour of the semiconductor devices and their mission profile which directly affects the lifetime and the cost of the whole converter. Therefore, the simulation platform is developed in Matlab/Simulink and PLECS simulation environment to analyse...... the dynamics of the system using different kinds of modulation strategies and analyzing different wind load conditions dependent on roughness classes. It is concluded that 60° discontinuous PWM modulation strategies show better thermal performance and increase the estimated lifetime of the converter...

Curcumin inhibits cholesterol uptake in Caco-2 cells by down-regulation of NPC1L1 expression

Directory of Open Access Journals (Sweden)

Duan Rui-Dong

2010-04-01

Full Text Available Abstract Background Curcumin is a polyphenol and the one of the principle curcuminoids of the spice turmeric. Its antioxidant, anti-cancer and anti-inflammatory effects have been intensively studied. Previous in vivo studies showed that administration of curcumin also decreased cholesterol levels in the blood, and the effects were considered to be related to upregulation of LDL receptor. However, since plasma cholesterol levels are also influenced by the uptake of cholesterol in the gut, which is mediated by a specific transporter Niemann-Pick Cl-like 1 (NPC1L1 protein, the present study is to investigate whether curcumin affects cholesterol uptake in the intestinal Caco-2 cells. Methods Caco-2 cells were cultured to confluence. The micelles composed of bile salt, monoolein, and 14C-cholesterol were prepared. We first incubated the cells with the micelles in the presence and absence of ezetimibe, the specific inhibitor of NPC1L1, to see whether the uptake of the cholesterol in the cells was mediated by NPC1L1. We then pretreated the cells with curcumin at different concentrations for 24 h followed by examination of the changes of cholesterol uptake in these curcumin-treated cells. Finally we determined whether curcumin affects the expression of NPC1L1 by both Western blot analysis and qPCR quantification. Results We found that the uptake of radioactive cholesterol in Caco-2 cells was inhibited by ezetimibe in a dose-dependent manner. The results indicate that the uptake of cholesterol in this study was mediated by NPC1L1. We then pretreated the cells with 25-100 μM curcumin for 24 h and found that such a treatment dose-dependently inhibited cholesterol uptake with 40% inhibition obtained by 100 μM curcumin. In addition, we found that the curcumin-induced inhibition of cholesterol uptake was associated with significant decrease in the levels of NPC1L1 protein and NPC1L1 mRNA, as analyzed by Western blot and qPCR, respectively. Conclusion

Curcumin inhibits cholesterol uptake in Caco-2 cells by down-regulation of NPC1L1 expression.

Science.gov (United States)

Feng, Dan; Ohlsson, Lena; Duan, Rui-Dong

2010-04-19

Curcumin is a polyphenol and the one of the principle curcuminoids of the spice turmeric. Its antioxidant, anti-cancer and anti-inflammatory effects have been intensively studied. Previous in vivo studies showed that administration of curcumin also decreased cholesterol levels in the blood, and the effects were considered to be related to upregulation of LDL receptor. However, since plasma cholesterol levels are also influenced by the uptake of cholesterol in the gut, which is mediated by a specific transporter Niemann-Pick Cl-like 1 (NPC1L1) protein, the present study is to investigate whether curcumin affects cholesterol uptake in the intestinal Caco-2 cells. Caco-2 cells were cultured to confluence. The micelles composed of bile salt, monoolein, and 14C-cholesterol were prepared. We first incubated the cells with the micelles in the presence and absence of ezetimibe, the specific inhibitor of NPC1L1, to see whether the uptake of the cholesterol in the cells was mediated by NPC1L1. We then pretreated the cells with curcumin at different concentrations for 24 h followed by examination of the changes of cholesterol uptake in these curcumin-treated cells. Finally we determined whether curcumin affects the expression of NPC1L1 by both Western blot analysis and qPCR quantification. We found that the uptake of radioactive cholesterol in Caco-2 cells was inhibited by ezetimibe in a dose-dependent manner. The results indicate that the uptake of cholesterol in this study was mediated by NPC1L1. We then pretreated the cells with 25-100 muM curcumin for 24 h and found that such a treatment dose-dependently inhibited cholesterol uptake with 40% inhibition obtained by 100 muM curcumin. In addition, we found that the curcumin-induced inhibition of cholesterol uptake was associated with significant decrease in the levels of NPC1L1 protein and NPC1L1 mRNA, as analyzed by Western blot and qPCR, respectively. Curcumin inhibits cholesterol uptake through suppression of NPC1L1

Influence of radiotherapy on CD4+ CD25high regulatory cells in peripheral blood of NPC patients

International Nuclear Information System (INIS)

Liu Li; Ding Qian; Song Yingqiu; Cao Rubo; Yao Junxia; Huang Shiang

2006-01-01

Objective: The current study was designed to investigate the changes in peripheral CD4 + CD25 high regulatory T (CD4 + CD25 high Tr) cells in patients with nasopharyngeal carcinoma (NPC) and the influence of radiotherapy on immunity function. Methods: The peripheral blood was collected from 36 patients with NPC and 30 healthy controls. By using monoclonal antibodies, the blood samples were evaluated with flow cytometry for lymphocyte subsets and Tr cells. Results: The ratio of CD4 + /CD8 + in the NPC group was not significantly less than that in the healthy controls (P>0.05), but the prevalence of the CD4 + CD25 high Tr cells was significantly higher than that of the healthy group [(2.76 ± 1.06)% versus (2.06 ± 0.98)%, P + CD25 high Tr cells was higher than before it [(4.88 ± 1.02)%, P + CD25 high Tr cells in peripheral blood of NPC patients with or without radiotherapy was significantly higher than those in healthy controls, which may be related to immunosupression and tumor progression in such patients. This finding suggests that CD4 + CD25 high Tr cells in peripheral blood of NPC patients can be a useful index for monitoring the immunity function. (authors)

Kemeny commission report. Comments by NPC (Nuclear Power Company)

Energy Technology Data Exchange (ETDEWEB)

1979-01-01

Following the accident at Three Mile island in March 1979 the Nuclear Power Company (NPC) has made evaluations of the available information and carried out preliminary investigations of the implications of the accident for all UK AGR's and for the PWR design. The results are summarized. Recommendations of the President's Commission are discussed with especial reference to those under the following headings: (1) The utility and its suppliers. (2) Training of operating personnel. (3) Technical assessment. It is concluded that while many of the relevant recommendations in the report of the President's Commission are already satisfied by UK practices for nuclear safety, and are being applied by NPC in their current programmes of work on AGR's and PWR's it is realised that it is of the utmost importance that complacent attitudes to safety are not allowed to develop. The accident at TMI and report of the Commision have provided a sharp reminder of the necessity to maintain unremitting vigilance in all aspects of design, construction and operation which are involved with the safety of the public and operators.

Oxygen activity measurements in simulated converter matte

CSIR Research Space (South Africa)

Tshilombo, KG

2007-01-01

Full Text Available to the composition of the gas atmosphere over the melt. The measured oxygen activity was generally close to that predicted by FactSage calculations. This indicates that such oxygen activity measurements could be useful to monitor iron removal during converting...

Normalization of Hepatic Homeostasis in the Npc1nmf164 Mouse Model of Niemann-Pick Type C Disease Treated with the Histone Deacetylase Inhibitor Vorinostat.

Science.gov (United States)

Munkacsi, Andrew B; Hammond, Natalie; Schneider, Remy T; Senanayake, Dinindu S; Higaki, Katsumi; Lagutin, Kirill; Bloor, Stephen J; Ory, Daniel S; Maue, Robert A; Chen, Fannie W; Hernandez-Ono, Antonio; Dahlson, Nicole; Repa, Joyce J; Ginsberg, Henry N; Ioannou, Yiannis A; Sturley, Stephen L

2017-03-17

Niemann-Pick type C (NP-C) disease is a fatal genetic lipidosis for which there is no Food and Drug Administration (FDA)-approved therapy. Vorinostat, an FDA-approved inhibitor of histone deacetylases, ameliorates lysosomal lipid accumulation in cultured NP-C patient fibroblasts. To assess the therapeutic potential of histone deacetylase inhibition, we pursued these in vitro observations in two murine models of NP-C disease. Npc1 nmf164 mice, which express a missense mutation in the Npc1 gene, were treated intraperitoneally, from weaning, with the maximum tolerated dose of vorinostat (150 mg/kg, 5 days/week). Disease progression was measured via gene expression, liver function and pathology, serum and tissue lipid levels, body weight, and life span. Transcriptome analyses of treated livers indicated multiple changes consistent with reversal of liver dysfunction that typifies NP-C disease. Significant improvements in liver pathology and function were achieved by this treatment regimen; however, NPC1 protein maturation and levels, disease progression, weight loss, and animal morbidity were not detectably altered. Vorinostat concentrations were >200 μm in the plasma compartment of treated animals but were almost 100-fold lower in brain tissue. Apolipoprotein B metabolism and the expression of key components of lipid homeostasis in primary hepatocytes from null ( Npc1 -/- ) and missense ( Npc1 nmf164 ) mutant mice were altered by vorinostat treatment, consistent with a response by these cells independent of the status of the Npc1 locus. These results suggest that HDAC inhibitors have utility to treat visceral NP-C disease. However, it is clear that improved blood-brain barrier penetration will be required to alleviate the neurological symptoms of human NP-C disease. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Normalization of Hepatic Homeostasis in the Npc1nmf164 Mouse Model of Niemann-Pick Type C Disease Treated with the Histone Deacetylase Inhibitor Vorinostat*

Science.gov (United States)

Munkacsi, Andrew B.; Hammond, Natalie; Schneider, Remy T.; Senanayake, Dinindu S.; Higaki, Katsumi; Lagutin, Kirill; Bloor, Stephen J.; Ory, Daniel S.; Maue, Robert A.; Chen, Fannie W.; Hernandez-Ono, Antonio; Dahlson, Nicole; Repa, Joyce J.; Ginsberg, Henry N.; Ioannou, Yiannis A.; Sturley, Stephen L.

2017-01-01

Niemann-Pick type C (NP-C) disease is a fatal genetic lipidosis for which there is no Food and Drug Administration (FDA)-approved therapy. Vorinostat, an FDA-approved inhibitor of histone deacetylases, ameliorates lysosomal lipid accumulation in cultured NP-C patient fibroblasts. To assess the therapeutic potential of histone deacetylase inhibition, we pursued these in vitro observations in two murine models of NP-C disease. Npc1nmf164 mice, which express a missense mutation in the Npc1 gene, were treated intraperitoneally, from weaning, with the maximum tolerated dose of vorinostat (150 mg/kg, 5 days/week). Disease progression was measured via gene expression, liver function and pathology, serum and tissue lipid levels, body weight, and life span. Transcriptome analyses of treated livers indicated multiple changes consistent with reversal of liver dysfunction that typifies NP-C disease. Significant improvements in liver pathology and function were achieved by this treatment regimen; however, NPC1 protein maturation and levels, disease progression, weight loss, and animal morbidity were not detectably altered. Vorinostat concentrations were >200 μm in the plasma compartment of treated animals but were almost 100-fold lower in brain tissue. Apolipoprotein B metabolism and the expression of key components of lipid homeostasis in primary hepatocytes from null (Npc1−/−) and missense (Npc1nmf164) mutant mice were altered by vorinostat treatment, consistent with a response by these cells independent of the status of the Npc1 locus. These results suggest that HDAC inhibitors have utility to treat visceral NP-C disease. However, it is clear that improved blood-brain barrier penetration will be required to alleviate the neurological symptoms of human NP-C disease. PMID:28031458

Snubber-less NPC inverter by a novel reduction technique of parasitic inductance for magnet power supplies

Energy Technology Data Exchange (ETDEWEB)

Koseki, K., E-mail: kunio.koseki@kek.jp; Morita, Y.

2014-10-11

The effects induced by parasitic inductance were studied in a neutral point clamped (NPC) inverter. The energy stored in the parasitic inductance by the output current causes a surge voltage during the turn-off period of semiconductor switches. The effect is serious in a magnet power supply for which a large excitation current is required. It is predicted by a circuit analysis that the parasitic inductance causes an electrical breakdown of the semiconductor switches. It was found that the most promising way to mitigate the effect is to reduce the parasitic inductance. With newly developed circuitry and layout of an NPC inverter, cancelation of the induced magnetic field, which is based on Ampere's circuital law, in power devices has been accomplished. The newly developed NPC inverter has been operated successfully with both a resistive dummy load and the dipole magnets in the main ring synchrotron at the J-PARC facility.

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.

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...

Prognostic value of anti-Epstein-Barr virus antibodies in nasopharyngeal carcinoma (NPC)

Energy Technology Data Exchange (ETDEWEB)

Liu, Mu-Tai; Yeh, Chi-Yuan [Chang-Hua Christian Hospital, Chang-Hua (Taiwan, Province of China)

1998-03-01

Eighty patients with histological diagnoses of nasopharyngeal cancer (NPC) were referred to Chang-Hua Christian Hospital for curative radiotherapy from 1985 to 1995. A mean dose of 7,020 cGy in 39 fractions was delivered to the primary tumor using a telecobalt-60 unit or 6-10 MV X-ray linear accelerator. Pre- and postradiotherapy serum levels of anti-Epstein-Barr virus (EBV)/VCA IgG and IgA were determined for all patients using the indirect immunoperoxidase assay. Multivariate analysis was done to determine which factors affected the patients` treatment outcome and survival. Five patients were excluded from this study due to incomplete radiotherapy, leaving 75 patients eligible for analysis. Overall local control was 77.3%, with a mean disease-free interval of 19.7 months. Factors affecting local control included radiation dose and pretreatment anti-EBV/VCA IgG titer. The overall 5-year actuarial survival for the 75 patients was 75%, with a median survival of 129.5 months. The 5-year actuarial survival rates for stage I+II, III, and IV patients were 90%, 40%, and 45%, respectively. Prognostic factors for survival included tumor histological type and pretreatment anti-EBV/VCA IgA titer, while prognostic factors for local control included total radiation dose received and pretreatment anti-EBV/VCA IgG titer. We found that there was a significant difference in the geometric mean titer of anti-EBV/VCA IgA antibodies before and after radiotherapy. Prognostic factors affecting NPC patients` actuarial survival included tumor histology and pretreatment IgA titer, while prognostic factors for local control of NPC included total radiation dose received and pretreatment IgG titer. (K.H.)

Prognostic value of anti-Epstein-Barr virus antibodies in nasopharyngeal carcinoma (NPC)

International Nuclear Information System (INIS)

Liu, Mu-Tai; Yeh, Chi-Yuan

1998-01-01

Eighty patients with histological diagnoses of nasopharyngeal cancer (NPC) were referred to Chang-Hua Christian Hospital for curative radiotherapy from 1985 to 1995. A mean dose of 7,020 cGy in 39 fractions was delivered to the primary tumor using a telecobalt-60 unit or 6-10 MV X-ray linear accelerator. Pre- and postradiotherapy serum levels of anti-Epstein-Barr virus (EBV)/VCA IgG and IgA were determined for all patients using the indirect immunoperoxidase assay. Multivariate analysis was done to determine which factors affected the patients' treatment outcome and survival. Five patients were excluded from this study due to incomplete radiotherapy, leaving 75 patients eligible for analysis. Overall local control was 77.3%, with a mean disease-free interval of 19.7 months. Factors affecting local control included radiation dose and pretreatment anti-EBV/VCA IgG titer. The overall 5-year actuarial survival for the 75 patients was 75%, with a median survival of 129.5 months. The 5-year actuarial survival rates for stage I+II, III, and IV patients were 90%, 40%, and 45%, respectively. Prognostic factors for survival included tumor histological type and pretreatment anti-EBV/VCA IgA titer, while prognostic factors for local control included total radiation dose received and pretreatment anti-EBV/VCA IgG titer. We found that there was a significant difference in the geometric mean titer of anti-EBV/VCA IgA antibodies before and after radiotherapy. Prognostic factors affecting NPC patients' actuarial survival included tumor histology and pretreatment IgA titer, while prognostic factors for local control of NPC included total radiation dose received and pretreatment IgG titer. (K.H.)

An active trap filter for high-power voltage source converters

DEFF Research Database (Denmark)

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

2015-01-01

This paper proposes a power electronic based device to actively trap the switching current ripples for highpower converters. Control principle and system design of the active trap filter are discussed first. Comparisons of the active trap filter with LCL and LLCL filters are then carried out...

Comparative evaluation of bidirectional dual active bridge DC-DC converter variants

NARCIS (Netherlands)

Sfakianakis, G.; Everts, J.; Huisman, H.; Lomonova, E.A.

2016-01-01

For the realization of DC-DC converters in automotive industry, the Dual Active Bridge (DAB) converter seems to be a promising choice because of its soft-switching and high-power-density capability. Contrary to the traditional 3 level - 3 level (3-3L) DAB, a 3 level - 5 level (3-5L) DAB can operate

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.

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...

POPS: the 60MW power converter for the PS accelerator: Control strategy and performances

CERN Document Server

Boattini, Fulvio; Skawinski, Gregory

2015-01-01

The main power supply of Proton-Synchrotron (PS) accelerator is one of the biggest at CERN. The old rotating machine system has been replaced with a new NPC based DC/DC power supply named POPS (Power system for PS main magnets) with capacitor banks as energy storage mean. POPS is in operation since February 2011. The operation of the PS accelerator requires a specific design of the control system with very high performance requirements in term of accuracy and precision. This paper describes the main lines of the control strategies analyzing the problems encountered and the solutions adopted. The performances of the converter are presented throughout the paper.

Loss Distribution Analysis of Three-Level Active Neutral-Point-Clamped (3L-ANPC) Converter with Different PWM Strategies

DEFF Research Database (Denmark)

Zhang, Gang; Yang, Yongheng; Iannuzzo, Francesco

2016-01-01

The three-level (3L) Active Neutral-Point-Clamped (ANPC) topology has been introduced to resolve the uneven loss distribution issue in the classical 3L Neutral-Point-Clamped (NPC) topology. This Pulse-Width-Modulation (PWM) strategy is then an important means to fully explore the potential benefits...... are separated in order to improve the loss distribution among the power devices. A comparison between the proposed strategy and other major PWM strategies for the loss distribution is also carried out in this paper. Benchmarking results show that the proposed strategy has effective and superior performance...

Epstein-barr virus latent membrane protein 1 (EBV-LMP1) and tumor proliferation rate as predictive factors of nasopharyngeal cancer (NPC) radiation response

Energy Technology Data Exchange (ETDEWEB)

Gondhowiardjo, S. [Univ. of Indonesia, Jakarta (Indonesia). Faculty of Medicine

2000-05-01

Irradiation is still the treatment of choice in NPC treatment as one of highest malignancy in Indonesia as well as in Southeast Asia. Up to now there is no accurate predictor on radiation response, since that the similar histo-morphological pattern, as a well-known prognostic factor can revealed a wide range of treatment outcomes. Purpose of the study is to established the influence of EBV-LMP 1 as the most important protein expressed by EBV oncogenes in cellular behavior such as proliferation rate, tumor aggressivity in NPC and to find out the role of both, proliferation rate and EBV-LMP1 expression as a predictor on NPC radiation response. One-hundred seventy-two paraffin-embedded biopsy specimens from NPC patients were analysed flow-cytometrically to obtain the S-phase fraction value as the proliferation parameter. From this group of patients, 81 fresh specimen biopsies could be collected, and the EBV-LMP 1 expression were detected by western blotting technique (mAB S12-Karolinska Institute) could be done. Several variables such as clinical stage, pathology pattern and radiation response were also collected. The radiation responses were established clinically (by nasopharyngoscopy), by CT scanning and pathologically. Sixty-five percent of our patients belong to the T3 and T4, whereby the N2-3 group consists 75% of them. Fourteen percent of the patients are Hsu type I, 48% are Hs type II and the rest belong to Hsu type III. Our study revealed that the mean SPF value was 14.62% (10.18%, which correlated (p<0.05) with the tumor and nodal sizes). The rate of positive expression of the EBV-LMP1 was 50%, and did not show a correlation with the proliferation activity as well as the radiation response. However, it showed a significant correlation with the tumor and nodal size. There was a significant correlation between this proliferation value with the radiation response calculated by both, bivariate as well as by multivariate analysis. The complete and incomplete

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

Indian Academy of Sciences (India)

Joseph Kiran Banda

Keywords. Field-oriented control; vector control of induction motor; active front end converter; power factor correction .... sinusoidal three-phase input currents applied to the stator. ... with necessary feed-forward terms are employed to control.

Interleaved Buck Converter with Variable Number of Active Phases and a Predictive Current Sharing Scheme

DEFF Research Database (Denmark)

Jakobsen, Lars Tønnes; Garcia, O.; Oliver, J. A.

2008-01-01

The efficiency of an interleaved Buck converter is typically low at light load conditions because of the switching losses in each of the switching stages. Improvements in the converter efficiency can be achieved by dynamically changing the number of active phases depending on the load current....... This paper addresses the issues related to the transient response of the converter when the number of active phases is changed by a digital control scheme. The problem arises because the current in the individual phases of the interleaved Buck converter will not be equal immediately after the controller has...... changed the number of active phases. This paper proposes a current equalisation scheme that adjusts the duty cycle of each phase in a manner that ensures equal average inductor current in all active phases in one or two PWM periods. The current equalisation scheme relies on the measurement of the output...

Demonstration of the serum antibody to Epstein-Barr virus specific DNA polymerased (EBV-DP) from patients with nasopharyngeal carcinoma (NPC)

Energy Technology Data Exchange (ETDEWEB)

Tan, R.S.; Li, J.S.; Grill, S.; Nutter, L.M.; Cheng, Y.C.

1986-03-05

Raji cells, an EBV genome carrying and nonproducer cell line, treated with tetradecanoyl-phorbol-13-acetate (TPA) and n-butyrate could induce a special DNA polymerase which has properties that are similar to the EBV-DP induced by TPA in P/sub 3/HR-I cells, an EBV producer cell line. Since EBV was found to have a strong association with NPC, and antibodies against EBV proteins or enzymes were found in high levels in sera from these patients, the possible presence of serum antibody against EBV-DP was examined. The serum titer of antibody to EBV-DP was found to have 190 +/- 84 units/ml serum (mean +/- S.D.) in 48 sera from patients with NPC. The titer in 52 healthy donors was 31.4 +/- 28 unit/ml serum (p < 0.01). The antibody was found to be associated with the IgG but not the IgA fraction. The antibody titers against EBV-DP were not correlated with the titer against EBV-DNase or VCA-IgA. Whether the antibody observed is against an EBV-DP core protein or its stimulating protein, as demonstrated by this laboratory previously, is still being investigated. This study demonstrated the high frequency and high titer of antibody against EBV-DP in serum from patients with NPC, and suggested the potential of utilizing this antibody titer to compliment other methods for the early diagnosis or prognosis of NPC.

Berberine suppresses tumorigenicity and growth of nasopharyngeal carcinoma cells by inhibiting STAT3 activation induced by tumor associated fibroblasts

International Nuclear Information System (INIS)

Tsang, Chi Man; Cheung, Yuk Chun; Lui, Vivian Wai-Yan; Yip, Yim Ling; Zhang, Guitao; Lin, Victor Weitao; Cheung, Kenneth Chat-Pan; Feng, Yibin; Tsao, Sai Wah

2013-01-01

Cortidis rhizoma (Huanglian) and its major therapeutic component, berberine, have drawn extensive attention in recent years for their anti-cancer properties. Growth inhibitory effects of berberine on multiple types of human cancer cells have been reported. Berberine inhibits invasion, induces cell cycle arrest and apoptosis in human cancer cells. The anti-inflammatory property of berberine, involving inhibition of Signal Transducer and Activator of Transcription 3 (STAT3) activation, has also been documented. In this study, we have examined the effects of berberine on tumorigenicity and growth of nasopharyngeal carcinoma (NPC) cells and their relationship to STAT3 signaling using both in vivo and in vitro models. Berberine effectively inhibited the tumorigenicity and growth of an EBV-positive NPC cell line (C666-1) in athymic nude mice. Inhibition of tumorigenic growth of NPC cells in vivo was correlated with effective inhibition of STAT3 activation in NPC cells inside the tumor xenografts grown in nude mice. In vitro, berberine inhibited both constitutive and IL-6-induced STAT3 activation in NPC cells. Inhibition of STAT3 activation by berberine induced growth inhibition and apoptotic response in NPC cells. Tumor-associated fibroblasts were found to secret IL-6 and the conditioned medium harvested from the fibroblasts also induced STAT3 activation in NPC cells. Furthermore, STAT3 activation by conditioned medium of tumor-associated fibroblasts could be blocked by berberine or antibodies against IL-6 and IL-6R. Our observation that berberine effectively inhibited activation of STAT3 induced by tumor-associated fibroblasts suggests a role of berberine in modulating the effects of tumor stroma on the growth of NPC cells. The effective inhibition of STAT3 activation in NPC cells by berberine supports its potential use in the treatment of NPC

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...

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

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...

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.

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 G 0 /G 1 phase. Tetrandrine induced DNA condensation by DAPI staining as well. In addition, we found that Tetrandrine induced Ca 2+ 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 Ca 2+ was released or not with Tetrandrine induced-apoptosis, we used the chelator of Ca 2+ 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.

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

NARCIS (Netherlands)

Wösten-van Asperen, Roelie M.; Bos, Albert P.; 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, René

2013-01-01

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 angiotensin

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

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

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......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...... on the passivity-based-stability analysis, a damping resistance selection method is proposed. Then, an admittance shaping method is developed to ensure the system stability in the presence of parasitic capacitance of the transmission line. Finally, experimental results are provided to show the validity...

Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

DEFF Research Database (Denmark)

Liu, Dong; Deng, Fujin; Chen, Zhe

2017-01-01

This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...... effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies...

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...

High power density dc/dc converter: Selection of converter topology

Science.gov (United States)

Divan, Deepakraj M.

1990-01-01

The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

Winding design of series AC inductor for dual active bridge converters

DEFF Research Database (Denmark)

Shen, Zhan; Wang, Huai; Shen, Yanfeng

2018-01-01

The ac resistance and parasitic capacitance of the inductor are the primary considerations in the winding design for the dual-active bridge converter (DAB). They are dependent of up to four independent structure variables. The interactive restrictions between those variables makes the design diff...

Hybrid Modulation of Bidirectional Three-Phase Dual-Active-Bridge DC Converters for Electric Vehicles

Directory of Open Access Journals (Sweden)

Yen-Ching Wang

2016-06-01

Full Text Available Bidirectional power converters for electric vehicles (EVs have received much attention recently, due to either grid-supporting requirements or emergent power supplies. This paper proposes a hybrid modulation of the three-phase dual-active bridge (3ΦDAB converter for EV charging systems. The designed hybrid modulation allows the converter to switch its modulation between phase-shifted and trapezoidal modes to increase the conversion efficiency, even under light-load conditions. The mode transition is realized in a real-time manner according to the charging or discharging current. The operation principle of the converter is analyzed in different modes and thus design considerations of the modulation are derived. A lab-scaled prototype circuit with a 48V/20Ah LiFePO4 battery is established to validate the feasibility and effectiveness.

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.

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.

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.

Niemann-Pick C1 like 1 gene expression is down-regulated by LXR activators in the intestine

International Nuclear Information System (INIS)

Duval, Caroline; Touche, Veronique; Tailleux, Anne; Fruchart, Jean-Charles; Fievet, Catherine; Clavey, Veronique; Staels, Bart; Lestavel, Sophie

2006-01-01

Niemann-Pick C1 like 1 (NPC1L1) is a protein critical for intestinal cholesterol absorption. The nuclear receptors peroxisome proliferator-activated receptor alpha (PPARα) and liver X receptors (LXRα and LXRβ) are major regulators of cholesterol homeostasis and their activation results in a reduced absorption of intestinal cholesterol. The goal of this study was to define the role of PPARα and LXR nuclear receptors in the regulation of NPC1L1 gene expression. We show that LXR activators down-regulate NPC1L1 mRNA levels in the human enterocyte cell line Caco-2/TC7, whereas PPARα ligands have no effect. Furthermore, NPC1L1 mRNA levels are decreased in vivo, in duodenum of mice treated with the LXR agonist T0901317. In conclusion, the present study identifies NPC1L1 as a novel LXR target gene further supporting a crucial role of LXR in intestinal cholesterol homeostasis

Intracellular trafficking of the free cholesterol derived from LDL cholesteryl ester is defective in vivo in Niemann-Pick C disease: insights on normal metabolism of HDL and LDL gained from the NP-C mutation.

Science.gov (United States)

Shamburek, R D; Pentchev, P G; Zech, L A; Blanchette-Mackie, J; Carstea, E D; VandenBroek, J M; Cooper, P S; Neufeld, E B; Phair, R D; Brewer, H B; Brady, R O; Schwartz, C C

1997-12-01

Niemann-Pick C disease (NP-C) is a rare inborn error of metabolism with hepatic involvement and neurological sequelae that usually manifest in childhood. Although in vitro studies have shown that the lysosomal distribution of LDL-derived cholesterol is defective in cultured cells of NP-C subjects, no unusual characteristics mark the plasma lipoprotein profiles. We set out to determine whether anomalies exist in vivo in the cellular distribution of newly synthesized, HDL-derived or LDL-derived cholesterol under physiologic conditions in NP-C subjects. Three affected and three normal male subjects were administered [14C]mevalonate as a tracer of newly synthesized cholesterol and [3H]cholesteryl linoleate in either HDL or LDL to trace the distribution of lipoprotein-derived free cholesterol. The rate of appearance of free [14C]- and free [3H]cholesterol in the plasma membrane was detected indirectly by monitoring their appearance in plasma and bile. The plasma disappearance of [3H]cholesteryl linoleate was slightly faster in NP-C subjects regardless of its lipoprotein origin. Appearance of free [14C] cholesterol ill the plasma (and in bile) was essentially identical in normal and affected individuals as was the initial appearance of free [3H]cholesterol derived from HDL, observed before extensive exchange occurred of the [3H]cholesteryl linoleate among lipoproteins. In contrast, the rate of appearance of LDL-derived free [3H]cholesterol in the plasma membrane of NP-C subjects, as detected in plasma and bile, was retarded to a similar extent that LDL cholesterol metabolism was defective in cultured fibroblasts of these affected subjects. These findings show that intracellular distribution of both newly synthesized and HDL-derived cholesterol are essentially unperturbed by the NP-C mutation, and therefore occur by lysosomal-independent paths. In contrast, in NP-C there is defective trafficking of LDL-derived cholesterol to the plasma membrane in vivo as well as in vitro

Clinical observation in nasopharyngeal carcinoma (NPC) treated with the anti-EGFR monoclonal antibody followed by helical tomotherapy

International Nuclear Information System (INIS)

Hou Jun; Feng Linchun; Cai Boning; Lu Na; Du Lei; Ma Lin; Xu Shouping; Xie Chuanbin

2011-01-01

Objective: To evaluate the clinical outcome and the acute toxicity in nasopharyngeal carcinoma (NPC) treated with tomotherapy followed by the anti-EGFR monoclonal antibody. Methods: Between March 2008 and November 2009, 34 newly diagnosed NPC patients were treated with helical tomotherapy combined with nimotuzumab or cetuximab. All the patients underwent tomotherapy at the dose of 70 Gy/33F for the gross tumor volume (pGTV ns ) and positive lymphnodes (GTV nd ), and 60 Gy/33F for the high risk clinical target volume (PTV 1 ), and 56 Gy/33 F for the low risk clinical target volume (PTV 2 ), respectively. 17 patients in group N were given weekly injection of 200 mg for 6-7 times and 17 patients in group C were given initial dosage 400 mg/m 2 followed by subsequent weekly dosage of 250 mg/m 2 for 6-7 times. Acute lesions were evaluated with the RTOG/EORTC criteria. Result: The median follow-up time was 22 months. The effective rates (CR + PR) in 3, 6 and 12 months were 14/17, 12/17, 12/17 in group N and 15/17, 14/17, 14/17 in group C. The 1 year survival rate was 15/17 in group Nand 17/17 in group C. Nimotuzumab had less acute mucositis reaction (u=2.25, P< 0.05), weight loss (t=2.56, P=0.02) and rash (u=4.36, P<0.01) compared with cetuximab. Conclusions: Helical tomotherapy combined with nimotuzumab or cetuximab was effective and made no difference in the short-term efficacy and 1 year survival rate for the patients with NPC. Nimotuzumab has less acute reaction than cetuximab. More studies should be done to prove long-term effects. (authors)

Prognosis and histology in Stage I nasopharyngeal carcinoma (NPC)

International Nuclear Information System (INIS)

Saw, D.; Ho, J.H.C.; Fong, M.; Chan, C.L.; Tse, C.H.; Lau, W.H.

1985-01-01

During 1969-1975, 212 new patients with Stage I nasopharyngeal carcinoma (NPC) with a tumor apparently confined to the nasopharynx were treated at Queen Elizabeth Hospital, Kowloon, Hong Kong. The initial histologies of 137 patients were available for review and further studies. The primary tumors were histologically classified into two major types - squamous cell carcinoma (35 patients) and undifferentiated carcinoma (102 patients). The latter was further divided into 4 sub-types: lymphoepithelioma of the Schmincke type, lymphoepithelioma of the Regaud type, spindle cell carcinoma, and undifferentiated carcinoma of the nasopharyngeal type. Such histological typing of the initial tumor was not of value in predicting the clinical outcome, whether in terms of 5-year crude or disease-free survival rate, or the tendency of the tumor to develop recurrence at the primary site, or distance metastases after a standardized course of radiation therapy. There is not significant correlation between the extent of mononuclear infiltration nor fibrosis in the tumor stroma and the survival or tumor control rates

Analysis and design of a parallel-connected single active bridge DC-DC converter for high-power wind farm applications

DEFF Research Database (Denmark)

Park, Kiwoo; Chen, Zhe

2013-01-01

This paper presents a parallel-connected Single Active Bridge (SAB) dc-dc converter for high-power applications. Paralleling lower-power converters can lower the current rating of each modular converter and interleaving the outputs can significantly reduce the magnitudes of input and output curre...

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

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...

Genetic variations of the NPC1L1 gene associated with hepatitis C virus (HCV) infection and biochemical characteristics of HCV patients in China.

Science.gov (United States)

Zhang, A-Mei; Zhang, Cheng-Lin; Song, Yuzhu; Zhao, Ping; Feng, Yue; Wang, Binghui; Li, Zheng; Liu, Li; Xia, Xueshan

2016-12-01

About 2% of the world population is infected with hepatitis C virus (HCV), a leading cause of hepatic cirrhosis and hepatocellular carcinoma. The Niemann-Pick C1-like 1 cholesterol absorption receptor (NPC1L1) was recently identified to be an important factor for HCV entry into host cells. Whether genetic variations of the NPC1L1 gene are associated with HCV infection is unknown. In this study, five single nucleotide polymorphisms (SNPs) of the NPC1L1 gene were analyzed in 261 HCV-infected individuals and 265 general controls from Yunnan Province, China. No significant differences were identified in genotypes or alleles of the SNPs between the two groups. After constructing haplotypes based on the five SNPs, a significant difference between HCV-infected individuals and general controls was shown for two haplotypes. Haplotype GCCTT appeared to be a protective factor and haplotype GCCCT was a risk factor for HCV-infected individuals. Genotypes of four SNPs correlated with biochemical characteristics of HCV-infected persons. Genotypes of SNPs rs799444 and rs2070607 were correlated with total bilirubin. Genotype TT of rs917098 was a risk factor for the gamma-glutamyltransferase level. Furthermore, HCV-infected individuals carrying genotype GG of rs41279633 showed statistically higher gamma-glutamyltransferase levels than HCV-infected persons with GT and TT. The results of this study identified the association between genetic susceptibility of the NPC1L1 gene and HCV infection, as well as biochemical characteristics of HCV-infected persons in Yunnan, China. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Oncogenic S1P signalling in EBV-associated nasopharyngeal carcinoma activates AKT and promotes cell migration through S1P receptor 3.

Science.gov (United States)

Lee, Hui Min; Lo, Kwok-Wai; Wei, Wenbin; Tsao, Sai Wah; Chung, Grace Tin Yun; Ibrahim, Maha Hafez; Dawson, Christopher W; Murray, Paul G; Paterson, Ian C; Yap, Lee Fah

2017-05-01

Undifferentiated nasopharyngeal carcinoma (NPC) is a cancer with high metastatic potential that is consistently associated with Epstein-Barr virus (EBV) infection. In this study, we have investigated the functional contribution of sphingosine-1-phosphate (S1P) signalling to the pathogenesis of NPC. We show that EBV infection or ectopic expression of the EBV-encoded latent genes (EBNA1, LMP1, and LMP2A) can up-regulate sphingosine kinase 1 (SPHK1), the key enzyme that produces S1P, in NPC cell lines. Exogenous addition of S1P promotes the migration of NPC cells through the activation of AKT; shRNA knockdown of SPHK1 resulted in a reduction in the levels of activated AKT and inhibition of cell migration. We also show that S1P receptor 3 (S1PR3) mRNA is overexpressed in EBV-positive NPC patient-derived xenografts and a subset of primary NPC tissues, and that knockdown of S1PR3 suppressed the activation of AKT and the S1P-induced migration of NPC cells. Taken together, our data point to a central role for EBV in mediating the oncogenic effects of S1P in NPC and identify S1P signalling as a potential therapeutic target in this disease. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Non-synchronous control of self-oscillating resonant converters

Science.gov (United States)

Glaser, John Stanley; Zane, Regan Andrew

2002-01-01

A self-oscillating switching power converter has a controllable reactance including an active device connected to a reactive element, wherein the effective reactance of the reactance and the active device is controlled such that the control waveform for the active device is binary digital and is not synchronized with the switching converter output frequency. The active device is turned completely on and off at a frequency that is substantially greater than the maximum frequency imposed on the output terminals of the active device. The effect is to vary the average resistance across the active device output terminals, and thus the effective output reactance, thereby providing converter output control, while maintaining the response speed of the converter.

High Voltage Gain Dual Active Bridge Converter with an Extended Operation Range for Renewable Energy Systems

DEFF Research Database (Denmark)

Zhang, Zhe; Tomas Manez, Kevin; Yudi, Xiao

2018-01-01

Bridge (P2DAB) converter, i.e. low-voltage (LV) side parallel and high-voltage (HV) side series, is proposed to achieve high voltage gain and low current stress over switching devices and transformer windings. Given the unmodified P2DAB power stage, by regulating the phase-shift angle between......Developing bidirectional dc-dc converters has become a critical research topic and gains more and more attention in recent years due to the extensive applications of smart grids with energy storages, hybrid and electrical vehicles and dc microgrids. In this paper, a Partial Parallel Dual Active...... the paralleled active bridges, the power equations and voltage gain are then modified, and therefore the operation range can be extended effectively. The operating principles of the proposed converter and its power characteristics under various operation modes are studied, and the design constraints...

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

Triterpenoids from Ganoderma lucidum inhibit the activation of EBV antigens as telomerase inhibitors.

Science.gov (United States)

Zheng, Dong-Shu; Chen, Liang-Shu

2017-10-01

Nasopharyngeal carcinoma (NPC) is a malignant disease that threatens the health of humans. To find effective agents for the inhibition of Epstein-Barr virus (EBV) infection, which is associated with NPC, a phytochemical investigation of Ganoderma lucidum was carried out in the present study. Five triterpenoids were identified, including ganoderic acid A (compound 1), ganoderic acid B (compound 2), ganoderol B (compound 3), ganodermanontriol (compound 4), and ganodermanondiol (compound 5), on the basis of spectroscopic analysis. An inhibition of EBV antigens activation assay was implemented to elucidate the triterpenoids from G. lucidum and potentially prevent NPC. All the triterpenoids showed significant inhibitory effects on both EBV EA and CA activation at 16 nmol. At 3.2 nmol, all the compounds moderately inhibited the activation of the two antigens. The activity of telomerase was inhibited by these triterpenoids at 10 µM. Molecular docking demonstrated that compound 1 was able to inhibit telomerase as a ligand. In addition, the physicochemical properties of these compounds were calculated to elucidate their drug-like properties. These results provided evidence for the application of these triterpenoids and whole G. lucidum in the treatment of NPC.

Control Strategy of Active Power Filter Based on Modular Multilevel Converter

Science.gov (United States)

Xie, Xifeng

2018-03-01

To improve the capacity, pressure resistance and the equivalent switching frequency of active power filter (APF), a control strategy of APF based on Modular Multilevel Converter (MMC) is presented. In this Control Strategy, the indirect current control method is used to achieve active current and reactive current decoupling control; Voltage Balance Control Strategy is to stabilize sub-module capacitor voltage, the predictive current control method is used to Track and control of harmonic currents. As a result, the harmonic current is restrained, and power quality is improved. Finally, the simulation model of active power filter controller based on MMC is established in Matlab/Simulink, the simulation proves that the proposed strategy is feasible and correct.

Novel Co3O4 Nanoparticles/Nitrogen-Doped Carbon Composites with Extraordinary Catalytic Activity for Oxygen Evolution Reaction (OER)

Science.gov (United States)

Yang, Xiaobing; Chen, Juan; Chen, Yuqing; Feng, Pingjing; Lai, Huixian; Li, Jintang; Luo, Xuetao

2018-03-01

Herein, Co3O4 nanoparticles/nitrogen-doped carbon (Co3O4/NPC) composites with different structures were prepared via a facile method. Structure control was achieved by the rational morphology design of ZIF-67 precursors, which were then pyrolyzed in air to obtain Co3O4/NPC composites. When applied as catalysts for the oxygen evolution reaction (OER), the M-Co3O4/NPC composites derived from the flower-like ZIF-67 showed superior catalytic activities than those derived from the rhombic dodecahedron and hollow spherical ZIF-67. The former M-Co3O4/NPC composite displayed a small over-potential of 0.3 V, low onset potential of 1.41 V, small Tafel slope of 83 mV dec-1, and a desirable stability. (94.7% OER activity was retained after 10 h.) The excellent performance of the flower-like M-Co3O4/NPC composite in the OER was attributed to its favorable structure. [Figure not available: see fulltext.

Cholesterol Perturbation in Mice Results in p53 Degradation and Axonal Pathology through p38 MAPK and Mdm2 Activation.

Directory of Open Access Journals (Sweden)

Qingyu Qin

Full Text Available Perturbation of lipid metabolism, especially of cholesterol homeostasis, can be catastrophic to mammalian brain, as it has the highest level of cholesterol in the body. This notion is best illustrated by the severe progressive neurodegeneration in Niemann-Pick Type C (NPC disease, one of the lysosomal storage diseases, caused by mutations in the NPC1 or NPC2 gene. In this study, we found that growth cone collapse induced by genetic or pharmacological disruption of cholesterol egress from late endosomes/lysosomes was directly related to a decrease in axonal and growth cone levels of the phosphorylated form of the tumor suppressor factor p53. Cholesterol perturbation-induced growth cone collapse and decrease in phosphorylated p53 were reduced by inhibition of p38 mitogen-activated protein kinase (MAPK and murine double minute (Mdm2 E3 ligase. Growth cone collapse induced by genetic (npc1-/- or pharmacological modification of cholesterol metabolism was Rho kinase (ROCK-dependent and associated with increased RhoA protein synthesis; both processes were significantly reduced by P38 MAPK or Mdm2 inhibition. Finally, in vivo ROCK inhibition significantly increased phosphorylated p53 levels and neurofilaments in axons, and axonal bundle size in npc1-/- mice. These results indicate that NPC-related and cholesterol perturbation-induced axonal pathology is associated with an abnormal signaling pathway consisting in p38 MAPK activation leading to Mdm2-mediated p53 degradation, followed by ROCK activation. These results also suggest new targets for pharmacological treatment of NPC disease and other diseases associated with disruption of cholesterol metabolism.

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

OpenAIRE

Xu, Shi-Zhou; He, Feng-You

2016-01-01

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 pe...

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...... 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...

AC-DC PFC Converter Using Combination of Flyback Converter and Full-bridge DC-DC Converter

Directory of Open Access Journals (Sweden)

Moh. Zaenal Efendi

2014-06-01

Full Text Available This paper presents a combination of power factor correction converter using Flyback converter and Full-bridge dc-dc converter in series connection. Flyback converter is operated in discontinuous conduction mode so that it can serve as a power factor correction converter and meanwhile Full-bridge dc-dc converter is used for dc regulator. This converter system is designed to produce a 86 Volt of output voltage and 2 A of output current. Both simulation and experiment results show that the power factor of this converter achieves up to 0.99 and meets harmonic standard of IEC61000-3-2. Keywords: Flyback Converter, Full-bridge DC-DC Converter, Power Factor Correction.

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...

EVALUATION PROGRAM SEVEN A SIDE FOOTBALL COACHING NATIONAL PARALIMPIC COMMITTEE (NPC) OF INDONESIA AT ASEAN PARAGAMES 2015 IN SINGAPORE

OpenAIRE

Asmawi, Moch.

2017-01-01

The purpose of the study was to evaluate program seven a side football National Paralimpic Committee (NPC) of Indonesia at ASEAN Paragames 2015 in Singapore. The research is qualitative research approach to evaluation using the model Context, Input, Process, and Product (CIPP). Triangulation method of collecting data using questionnaires, interviews, document study and observation. Research result that: 1) Evaluation of Context: have a legal basis and strong government policy, vision mission ...

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...... 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...

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...

Pre-symptomatic activation of antioxidant responses and alterations in glucose and pyruvate metabolism in Niemann-Pick Type C1-deficient murine brain.

Directory of Open Access Journals (Sweden)

Barry E Kennedy

Full Text Available Niemann-Pick Type C (NPC disease is an autosomal recessive neurodegenerative disorder caused in most cases by mutations in the NPC1 gene. NPC1-deficiency is characterized by late endosomal accumulation of cholesterol, impaired cholesterol homeostasis, and a broad range of other cellular abnormalities. Although neuronal abnormalities and glial activation are observed in nearly all areas of the brain, the most severe consequence of NPC1-deficiency is a near complete loss of Purkinje neurons in the cerebellum. The link between cholesterol trafficking and NPC pathogenesis is not yet clear; however, increased oxidative stress in symptomatic NPC disease, increases in mitochondrial cholesterol, and alterations in autophagy/mitophagy suggest that mitochondria play a role in NPC disease pathology. Alterations in mitochondrial function affect energy and neurotransmitter metabolism, and are particularly harmful to the central nervous system. To investigate early metabolic alterations that could affect NPC disease progression, we performed metabolomics analyses of different brain regions from age-matched wildtype and Npc1 (-/- mice at pre-symptomatic, early symptomatic and late stage disease by (1H-NMR spectroscopy. Metabolic profiling revealed markedly increased lactate and decreased acetate/acetyl-CoA levels in Npc1 (-/- cerebellum and cerebral cortex at all ages. Protein and gene expression analyses indicated a pre-symptomatic deficiency in the oxidative decarboxylation of pyruvate to acetyl-CoA, and an upregulation of glycolytic gene expression at the early symptomatic stage. We also observed a pre-symptomatic increase in several indicators of oxidative stress and antioxidant response systems in Npc1 (-/- cerebellum. Our findings suggest that energy metabolism and oxidative stress may present additional therapeutic targets in NPC disease, especially if intervention can be started at an early stage of the disease.

Loss and thermal redistributed modulation methods for three-level neutral-point-clamped wind power inverter undergoing Low Voltage Ride Through

DEFF Research Database (Denmark)

Ma, Ke; Blaabjerg, Frede

2012-01-01

The three-level neutral-point-clamped (3L-NPC) converter is a promising multilevel topology in the application of mega-watts wind power generation system. However, the growing requirements by grid codes may impose high stress and even give reliability problem to this converter topology. This paper...... modulation methods, the thermal distribution in the 3L-NPC wind power inverter undergoing LVRT becomes more equal, and the junction temperature of the most stressed devices can be also relieved. Also the control ability of DC-bus neutral point potential, which is one of the crucial considerations for the 3L...

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...... cognitive function during hypoglycaemia. METHODS: Sixteen healthy volunteers selected by either particularly high or low serum ACE activity were subjected to hypoglycaemia (plasma glucose 2.7 mmol/L). Cognitive function was assessed by choice reaction tests. RESULTS: Despite a similar hypoglycaemic stimulus...... in the two groups, only the group with high ACE activity showed significant deterioration in cognitive performance during hypoglycaemia. In the high ACE group mean reaction time (MRT) in the most complex choice reaction task was prolonged and error rate (ER) was increased in contrast to the low ACE group...

Luminescent converter of neodymium laser radiation

International Nuclear Information System (INIS)

Ryba-Romanowski, W.; Golab, S.

1992-01-01

The new luminescent converter of neodymium laser radiation has been worked out. Activated inorganic compounds of ytterbium and erbium ions has been used as luminescent agent. The multi-component inorganic glass containing tellurium oxide as well as boron, sodium, magnesium and zinc oxides has been applied as a converter matrix

Multi-Objective Optimization Control for the Aerospace Dual-Active Bridge Power Converter

Directory of Open Access Journals (Sweden)

Tao Lei

2018-05-01

Full Text Available With the development of More Electrical Aircraft (MEA, the electrification of secondary power systems in aircraft is becoming more and more common. As the key power conversion device, the dual active bridge (DAB converter is the power interface for the energy storage system with the high voltage direct current (HVDC bus in aircraft electrical power systems. In this paper, a DAB DC-DC converter is designed to meet aviation requirements. The extended dual phase shifted control strategy is adopted, and a multi-objective genetic algorithm is applied to optimize its operating performance. Considering the three indicators of inductance current root mean square root (RMS value, negative reverse power and direct current (DC bias component of the current for the high frequency transformer as the optimization objectives, the DAB converter’s optimization model is derived to achieve soft switching as the main constraint condition. Optimized methods of controlling quantity for the DAB based on the evolution and genetic algorithm is used to solve the model, and a number of optimal control parameters are obtained under different load conditions. The results of digital, hard-in-loop simulation and hardware prototype experiments show that the three performance indexes are all suppressed greatly, and the optimization method proposed in this paper is reasonable. The work of this paper provides a theoretical basis and researching method for the multi-objective optimization of the power converter in the aircraft electrical power system.

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.

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......, 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...

Flicker Mitigation by Active Power Control of Variable-Speed Wind Turbines With Full-Scale Back-to-Back Power Converters

DEFF Research Database (Denmark)

Hu, Weihao; Chen, Zhe; Wang, Zhaoan

2009-01-01

/EMTDC. Flicker emission of this system is investigated. Reactive power compensation is mostly adopted for flicker mitigation. However, the flicker mitigation technique shows its limits, when the grid impedance angle is low in some distribution networks. A new method of flicker mitigation by controlling active...... power is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the dc-link voltage of the full-scale converter. Simulation results show that damping the 3p active power oscillation by using the flicker mitigation controller...... is an effective means for flicker mitigation of variable-speed wind turbines with full-scale back-to-back power converters during continuous operation....

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.

A closed loop control strategy for a frequency-only converter with high efficiency

Energy Technology Data Exchange (ETDEWEB)

Benaboud, A.; Rufer, A. [Ecole Polytechnique Federale de Lausanne (Switzerland). Industrial Electronics Lab

2007-07-01

Three-level neutral point clamped (NPC) inverters are used for medium voltage applications. They allow the output voltage to spread on 3 levels, thus increasing it above the voltage limits of classical semiconductors. This paper presented an efficient new control strategy for a three-level NPC inverter that can be used for high power applications. Many electric power generators use gas turbines as power sources, coupled through a mechanical gearbox in order to adapt their synchronous speed to the optimal rotation speed of the turbine. Replacing the mechanical gearbox with a flexible electronic solution would be more efficient. The efficiency of the new control strategy can be attributed to the use of square-wave modulation, whose key advantage is the quasi absence of switching losses. In this modulation, only the frequency can be adapted between the input and the output voltages. However, their magnitudes are not freely controllable. The active and reactive powers produced can be controlled by the generator's excitation, as well as both the angle shift between the generator's and rectifier's voltages and between the inverter's and network's voltages. The capabilities of the proposed control strategy were highlighted during simulation of different operating points. 7 refs., 18 figs.

Relationship between changed alveolar-capillary permeability and angiotensin converting enzyme activity in serum in sarcoidosis.

OpenAIRE

Eklund, A; Blaschke, E

1986-01-01

The effect of altered alveolar-capillary permeability on angiotensin converting enzyme (ACE) activity in serum (SACE) was studied in 45 patients with sarcoidosis and 21 healthy controls. In sarcoidosis increased albumin concentrations in the bronchoalveolar lavage fluid (L albumin) and increased ratios of L albumin to albumin in serum (S albumin) indicated an increased permeability of the alveolar-capillary membrane. ACE activity in the lavage fluid (LACE) was correlated with the number of al...

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...

Optimization Control of Bidirectional Cascaded DC-AC Converter Systems

DEFF Research Database (Denmark)

Tian, Yanjun

in bidirectional cascaded converter. This research work analyses the control strategies based on the topology of dual active bridges converter cascaded with a three phase inverter. It firstly proposed a dc link voltage and active power coordinative control method for this cascaded topology, and it can reduce dc....... The connections of the renewable energy sources to the power system are mostly through the power electronic converters. Moreover, for high controllability and flexibility, power electronic devices are gradually acting as the interface between different networks in power systems, promoting conventional power...... the bidirectional power flow in the distribution level of power systems. Therefore direct contact of converters introduces significant uncertainties to power system, especially for the stability and reliability. This dissertation studies the optimization control of the two stages directly connected converters...

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.

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

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 voltage control on the basis of the continuous model. The design method for optimum performance is discussed. The implementation of the proposed modulation strategy and the controller is very simple. The controller is implemented in a 7.5 kW induction machine based drive with only 14 ìF dc-link capacitors...

SIG Galileo final converter technical summary report

International Nuclear Information System (INIS)

Hinderman, J.D.

1979-05-01

The report is primarily concerned with the work performed for DOE on converter development and fabrication for the NASA Galileo Jupiter mission as a DOE prime contractor with interface primarily with Teledyne Energy Systems. The activities reported on were directed toward design, analysis and testing of modules and converters SN-1 thru SN-7 and attendant Quality Control and Reliability effort. Although assembly and testing of SN-1 was not accomplished due to the stop work order, the design was virtually completed and a significant amount of subcontracting and manufacturing of both module and converter components was underway. These subcontracting and manufacturing activities were selectively closed down depending upon degree of completion and material or hardware potential usage in the Technology Program

Converter topologies and control

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, Fernando; Qin, Hengsi; Chapman, Patrick

2018-05-01

An inverter includes a transformer that includes a first winding, a second winding, and a third winding, a DC-AC inverter electrically coupled to the first winding of the transformer, a cycloconverter electrically coupled to the second winding of the transformer, 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.

Active energy recovery clamping circuit to improve the performance of power converters

Science.gov (United States)

Whitaker, Bret; Barkley, Adam

2017-05-09

A regenerative clamping circuit for a power converter using clamping diodes to transfer charge to a clamping capacitor and a regenerative converter to transfer charge out of the clamping capacitor back to the power supply input connection. The regenerative converter uses a switch connected to the midpoint of a series connected inductor and capacitor. The ends of the inductor and capacitor series are connected across the terminals of the power supply to be in parallel with the power supply.

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.

Buck Converter with Soft-Switching Cells for PV Panel Applications

Directory of Open Access Journals (Sweden)

Cheng-Tao Tsai

2016-03-01

Full Text Available In power conversion of photovoltaic (PV energy, a hard-switching buck converter always generates some disadvantages. For example, serious electromagnetic interference (EMI, high switching losses, and stresses on an active switch (metal-oxide-semiconductor-field-effect-transistor, MOSFET, and high reverse-recovery losses of a freewheeling diode result in low conversion efficiency. To release these disadvantages, a buck converter with soft-switching cells for PV panel applications is proposed. To create zero-voltage-switching (ZVS features of the active switches, a simple active soft-switching cell with an inductor, a capacitor, and a MOSFET is incorporated into the proposed buck converter. Therefore, the switching losses and stresses of the active switches and EMI can be reduced significantly. To reduce reverse-recovery losses of a freewheeling diode, a simple passive soft-switching cell with a capacitor and two diodes is implemented. To verify the performance and the feasibility of the proposed buck converter with soft-switching cells for PV panel applications, a prototype soft-switching buck converter is built and implemented by using a maximum-power-point-tracking (MPPT method. Simulated and experimental results are presented from a 100 W soft-switching buck converter for PV panel applications.

High Voltage Gain Dual Active Bridge Converter with an Extended Operation Range for Renewable Energy Systems

DEFF Research Database (Denmark)

Zhang, Zhe; Tomas Manez, Kevin; Yudi, Xiao

2018-01-01

Developing bidirectional dc-dc converters has become a critical research topic and gains more and more attention in recent years due to the extensive applications of smart grids with energy storages, hybrid and electrical vehicles and dc microgrids. In this paper, a Partial Parallel Dual Active...

Elevated serum angiotensin-converting enzyme (SACE) activity in acute pulmonary histoplasmosis.

Science.gov (United States)

Davies, S F; Rohrbach, M S; Thelen, V; Kuritsky, J; Gruninger, R; Simpson, M L; DeRemee, R A

1984-03-01

Serum angiotensin-converting enzyme (SACE) levels were measured in 44 subjects six weeks after acute pulmonary histoplasmosis. All patients were infected in a common-source outbreak of histoplasmosis which occurred on one day. All patients had both strictly defined clinical and serologic evidence of infection. The SACE activity was elevated at six weeks compared to normal controls, and seven of the 44 had levels more than 2 SD above the normal mean. SACE levels were also measured at three and 24 weeks after acute infection in a smaller number of the same subjects. Serial observations demonstrated that all subjects (including those with normal and elevated SACE at six weeks) had a rise and fall in SACE activity following symptomatic acute pulmonary histoplasmosis. Our findings suggest that elevated SACE does not reliably separate sarcoidosis from histoplasmosis, although elevations in histoplasmosis are much less common and may occur only briefly following acute pulmonary histoplasmosis. More important, it seems that SACE activity rises acutely in all patients with symptomatic acute histoplasmosis and then falls gradually toward baseline over several months, coinciding temporally with the granulomatous response.

Generalized stability regions of current control for LCL-filtered grid-connected converters without passive or active damping

DEFF Research Database (Denmark)

Tang, Yi; Yoon, Changwoo; Zhu, Rongwu

2015-01-01

This paper investigates the stability regions of current control for LCL-filtered grid-connected converters, where no active or passive damping is required to stabilize the closed-loop control system. It is already identified in the literature that if the LCL resonance frequency is placed within 1....../6 to 1/2 of the system sampling frequency, the grid current control can be directly used without damping. If the resonance frequency is smaller than 1/6 of the sampling frequency, the converter current control should then be adopted. This paper further extends the analysis to the cases where...... the resonance frequency could be larger than 1/2 of the sampling frequency, and derives the complete stability regions for both grid and converter current control. Interestingly, it is found that for any given LCL-filter design, there will always be one stable current control design without any damping, which...

Development of a magnet power supply with sub-ppm ripple performance for J-PARC with a novel common-mode rejection method with an NPC inverter

International Nuclear Information System (INIS)

Koseki, K.; Kurimoto, Y.

2014-01-01

The mechanism that generates common-mode noise in inverter circuits, which are widely used in magnet power supplies, was evaluated by a circuit simulation. By following asymmetric operational sequences, pulsed voltage is applied to the parasitic capacitance of power cables that causes a common-mode current at each switching period of the semiconductor switches. Common-mode noise was also found to disturb the normal-mode excitation current by inducing higher frequency components in the applied voltage to the magnet. To eliminate the disturbing effect by the common-mode noise, a newly developed operational method that uses a neutral point clamped, NPC, inverter with reduced switching sequences was evaluated both by a circuit simulation and experimentally. The operational method for the NPC inverter could sufficiently reduce the common-mode noise. A high-power test operation performed using 16 bending magnets at the J-PARC facility achieved a ripple of less than 1 ppm in the excitation current

Development of a magnet power supply with sub-ppm ripple performance for J-PARC with a novel common-mode rejection method with an NPC inverter

Energy Technology Data Exchange (ETDEWEB)

Koseki, K., E-mail: kunio.koseki@kek.jp; Kurimoto, Y.

2014-05-21

The mechanism that generates common-mode noise in inverter circuits, which are widely used in magnet power supplies, was evaluated by a circuit simulation. By following asymmetric operational sequences, pulsed voltage is applied to the parasitic capacitance of power cables that causes a common-mode current at each switching period of the semiconductor switches. Common-mode noise was also found to disturb the normal-mode excitation current by inducing higher frequency components in the applied voltage to the magnet. To eliminate the disturbing effect by the common-mode noise, a newly developed operational method that uses a neutral point clamped, NPC, inverter with reduced switching sequences was evaluated both by a circuit simulation and experimentally. The operational method for the NPC inverter could sufficiently reduce the common-mode noise. A high-power test operation performed using 16 bending magnets at the J-PARC facility achieved a ripple of less than 1 ppm in the excitation current.

High-performance feedback-type active damping of LCL-filtered voltage source converters

DEFF Research Database (Denmark)

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

2015-01-01

a generalized impedance-based model of grid current control with feedback-type active damping. Then, a controller design method based on the z-domain root contours and frequency-domain passivity theorem is proposed. It not only allows a co-design of the grid current controller and damping controller......Active damping of LCL-filter resonance based on single-state feedback control is widely used with voltage source converters. Its robustness against grid impedance variation has always been a major concern with its controller design. To deal with this issue, this paper begins by developing......, but ensures also a robust stabilization against the grid parameters variations. For illustration, the approach is applied to design three single-state feedback-damping schemes, and their damping robustness are compared under both inductive and resonant grid impedances. Experimental results validate...

DISTINCT: Diversity in Solar Talent Through INnovative Curriculum and Training: An Integrated Research and Education Approach towards Creating Diversity and Advancing Utility-Scale Solar Technology

Energy Technology Data Exchange (ETDEWEB)

Krishnaswami, Hariharan [Univ. of Texas, San Antonio, TX (United States)

2018-02-05

The DISTINCT project research objective is to develop an innovative N-port power converter for a utility-scale PV system that is modular, compact and cost-effective and that will enable the integration of a high-frequency, high-voltage solid-state transformer. The novelty of the proposed research is the electrical power conversion architecture using an N-port converter system that replaces the output 60Hz transformer with an integrated high-frequency low-weight solid-state transformer reducing power electronics and BOS costs to meet SunShot goals through modularity and direct high-voltage interconnection. A challenge in direct integration with a 13.8kV line is the high voltage handling capacity of the converters combined with high efficiency operation. The front-end converter for each port is a Neutral-Point Clamped (NPC) Multi-Level dc-dc Dual-Active Bridge (ML-DAB) which allows Maximum Power Point Tracking (MPPT). The integrated high frequency transformer provides the galvanic isolation between the PV and grid side and also steps up the low dc voltage from PV source. Following the ML-DAB stage, in each port, is an inverter with H-bridge configuration or NPC configuration. N number of NPC inverters’ outputs are cascaded to attain the per-phase line-to-neutral voltage to connect directly to the distribution grid (i.e. 13.8 kV). The cascaded inverters have the inherent advantage of using lower rated devices, smaller filters and low Total Harmonic Distortion (THD) required for PV grid interconnection. Our analysis and simulation results show improved performance on cost, efficiency, service life with zero downtime and THD. A comprehensive control scheme is presented to ensure the maximum power from each port and each phase are sent to the grid. A functional prototype of a 2-port converter with ML-DAB and cascaded H-bridges has been designed, built, and tested in a laboratory setup to verify the target technical metrics. The N-port converter system due to its

Convertible bond valuation focusing on Chinese convertible bond market

OpenAIRE

Yang, Ke

2010-01-01

This paper mainly discusses the methods of valuation of convertible bonds in Chinese market. Different from common convertible bonds in European market, considering the complicate features of Chinese convertible bond, this paper represents specific pricing approaches for pricing convertible bonds with different provisions along with the increment of complexity of these provisions. More specifically, this paper represents the decomposing method and binomial tree method for pricing both of Non-...

Correlation of Endothelin-1 Concentration and Angiotensin-Converting Enzyme Activity with the Staging of Liver Fibrosis

OpenAIRE

Kardum, Duško; Fabijanić, Damir; Lukić, Anita; Romić, Željko; Petrovečki, Mladen; Bogdanović, Zoran; Jurić, Klara; Urek-Crnčević, Marija; Banić, Marko

2012-01-01

Increased serum angiotensin-converting enzyme (SACE) activity and serum concentration of endothelin-1 (ET-1) were found in liver cirrhosis. We investigated a correlation between the different stages of liver fibrosis and SACE activity and serum ET-1 concentration. Seventy patients with pathohistologically established chronic liver disease were divided in three groups according to Ishak criteria for liver fibrosis: minimal fibrosis (Ishak score 0–1, n=20), medium fibrosis (Ishak sc...

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.

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)

Association between angiotensin II receptor gene polymorphism and serum angiotensin converting enzyme (SACE) activity in patients with sarcoidosis

OpenAIRE

Takemoto, Y.; Sakatani, M.; Takami, S.; Tachibana, T.; Higaki, J.; Ogihara, T.; Miki, T.; Katsuya, T.; Tsuchiyama, T.; Yoshida, A.; Yu, H.; Tanio, Y.; Ueda, E.

1998-01-01

BACKGROUND—Serum angiotensin converting enzyme (SACE) is considered to reflect disease activity in sarcoidosis. SACE activity is increased in many patients with active sarcoid lesions. The mechanism for the increased SACE activity in this disease has not been clarified. ACE insertion/deletion (I/D) gene polymorphism has been reported to have an association with SACE levels in sarcoidosis, but no evidence of an association between angiotensin II receptor gene polymorphism and SA...

Angiotensin-converting enzyme activity in Cavalier King Charles Spaniels with an ACE gene polymorphism and myxomatous mitral valve disease

DEFF Research Database (Denmark)

Meurs, Kathryn M.; Olsen, Lisbeth H.; Reimann, Maria J.

2018-01-01

a canine ACE gene polymorphism associated with a decrease in angiotensin-converting enzyme (ACE) activity. The aim of this study was to evaluate for the prevalence of the ACE polymorphism in CKCS with mitral valve disease and to determine whether the presence of the polymorphism is associated......Objectives Myxomatous mitral valve disease (MMVD) is the most common heart disease in the dog. It is particularly common in the Cavalier King Charles Spaniel (CKCS) breed and affected dogs are frequently managed with angiotensin-converting enzyme inhibitors (ACE-I). We have previously identified...... with alterations in ACE activity at different stages of cardiac disease. Methods Seventy-three dogs with a diagnosis of mitral valve disease were evaluated and a blood sample was drawn for ACE polymorphism genotyping and ACE activity measurement. Results Forty-three dogs were homozygous for the ACE polymorphism...

A column level, low power, 1 M sample/s double ramp A/D converter for monolithic active pixel sensors in high energy physics

International Nuclear Information System (INIS)

Pillet, N.; Heini, S.; Hu, Y.

2010-01-01

Monolithic active pixel sensors (MAPS) using standard low cost CMOS technologies available from industrial manufacturers have demonstrated excellent tracking performances for minimum ionizing particles. The need for highly granular, fast, thin sensors with a full digital output drives an R and D effort, aiming to design and optimize a low power high speed A/D converter integrated at the column level. Following this main issue, a double digital ramp A/D converter has been proposed for CMOS monolithic active pixel sensors in this paper. This A/D converter responds to the constraints of size, power dissipation and precision for CMOS sensors for particle detection. It also represents a first step in order to reach the high speed of conversion needed for this kind of application. The A/D converter has a resolution of 4 bits for conversion speed of 1 M sample/s with only 264 μW of static consumption in a very particular pitch of 25 μmx900 μm.

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...

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.

Abalone Protein Hydrolysates: Preparation, Angiotensin I Converting Enzyme Inhibition and Cellular Antioxidant Activity.

Science.gov (United States)

Park, Soo Yeon; Je, Jae-Young; Hwang, Joung-Youl; Ahn, Chang-Bum

2015-09-01

Abalone protein was hydrolyzed by enzymatic hydrolysis and the optimal enzyme/substrate (E/S) ratios were determined. Abalone protein hydrolysates (APH) produced by Protamex at E/S ratio of 1:100 showed angiotensin I converting enzyme inhibitory activity with IC50 of 0.46 mg/mL, and APH obtained by Flavourzyme at E/S ratio of 1:100 possessed the oxygen radical absorbance capacity value of 457.6 μM trolox equivalent/mg sample. Flavourzyme abalone protein hydrolysates (FAPH) also exhibited H2O2 scavenging activity with IC50 of 0.48 mg/mL and Fe(2+) chelating activity with IC50 of 2.26 mg/mL as well as high reducing power. FAPH significantly (P<0.05) protected H2O2-induced hepatic cell damage in cultured hepatocytes, and the cell viability was restored to 90.27% in the presence of FAPH. FAPH exhibited 46.20% intracellular ROS scavenging activity and 57.89% lipid peroxidation inhibition activity in cultured hepatocytes. Overall, APH may be useful as an ingredient for functional foods.

Impairments in cognition and neural precursor cell proliferation in mice expressing constitutively active glycogen synthase kinase-3

Directory of Open Access Journals (Sweden)

Marta ePardo

2015-03-01

Full Text Available ABSTRACTBrain glycogen synthase kinase-3 (GSK3 is hyperactive in several neurological conditions that involve impairments in both cognition and neurogenesis. This raises the hypotheses that hyperactive GSK3 may directly contribute to impaired cognition, and that this may be related to deficiencies in neural precursor cells (NPC. To study the effects of hyperactive GSK3 in the absence of disease influences, we compared adult hippocampal NPC proliferation and performance in three cognitive tasks in male and female wild-type mice and GSK3 knockin mice, which express constitutively active GSK3. NPC proliferation was ~40% deficient in both male and female GSK3 knockin mice compared with wild-type mice. Environmental enrichment (EE increased NPC proliferation in male, but not female, GSK3 knockin mice and wild-type mice. Male and female GSK3 knockin mice exhibited impairments in novel object recognition, temporal order memory, and coordinate spatial processing compared with gender-matched wild-type mice. EE restored impaired novel object recognition and temporal ordering in both sexes of GSK3 knockin mice, indicating that this repair was not dependent on NPC proliferation, which was not increased by EE in female GSK3 knockin mice. Acute 1 hr pretreatment with the GSK3 inhibitor TDZD-8 also improved novel object recognition and temporal ordering in male and female GSK3 knockin mice. These findings demonstrate that hyperactive GSK3 is sufficient to impair adult hippocampal NPC proliferation and to impair performance in three cognitive tasks in both male and female mice, but these changes in NPC proliferation do not directly regulate novel object recognition and temporal ordering tasks.

Performance evaluation of a three-phase dual active bridge DC-DC converter with different transformer winding configurations

NARCIS (Netherlands)

Baars, N.; Everts, J.; Wijnands, K.; Lomonova, E.

2016-01-01

This paper investigates the impact of three transformer winding configurations, i.e. the Y-Y, the Y-Delta, and the Delta-Delta configuration, on the performance of a three-phase dual active bridge (DAB) dc–dc converter. For each configuration, equations for the phase currents, power flow, and zero

A Fast-Processing Modulation Strategy for Three-Phase Four-Leg Neutral-Point-Clamped Inverter Based on the Circuit-Level Decoupling Concept

DEFF Research Database (Denmark)

Ghoreishy, Hoda; Zhang, Zhe; Thomsen, Ole Cornelius

2012-01-01

In this paper, a modulation strategy based on the circuit-level decoupling concept is proposed and investigated for the three-level four-leg neutral-point-clamped (NPC) inverter,with the aim of delivering power to all sorts of loads, linear/nonlinear and balanced/unbalanced. By applying the propo......In this paper, a modulation strategy based on the circuit-level decoupling concept is proposed and investigated for the three-level four-leg neutral-point-clamped (NPC) inverter,with the aim of delivering power to all sorts of loads, linear/nonlinear and balanced/unbalanced. By applying...... the proposed modulation strategy, the four-leg NPC inverter can be decoupled into three three-level Buck converters in each defined operating section. This makes the controller design much simpler compared to the conventional four-leg NPC inverter controllers. Also, this technique can be implemented...

Angiotensin-converting enzyme and its clinical significance--a review.

OpenAIRE

Studdy, P R; Lapworth, R; Bird, R

1983-01-01

There have been considerable advances in understanding the metabolic role of the endothelial lining cells of the blood vessels. Angiotensin-converting enzyme activity is concentrated in these cells, especially those lining the pulmonary circulation. The enzyme exerts control over systemic vascular tone indirectly through the powerful pressor effect of angiotensin II. A number of therapeutic agents are now available which directly inhibit converting enzyme activity and thereby effect a reducti...

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.

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.

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.

A Multi-Functional Power Electronic Converter in Distributed Generation Power Systems

DEFF Research Database (Denmark)

Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim

2005-01-01

of the converter interfacing a wind power generation unit is also given. The power electronic interface performs the optimal operation in the wind turbine system to extract the maximum wind power, while it also plays a key role in a hybrid compensation system that consists of the active power electronic converter......This paper presents a power electronic converter which is used as an interface for a distributed generation unit/energy storage device, and also functioned as an active power compensator in a hybrid compensation system. The operation and control of the converter have been described. An example...... and passive filters connected to each distorting load or distributed generation (DG) unit. The passive filters are distributely located to remove major harmonics and provide reactive power compensation. The active power electronic filter corrects the system unbalance, removes the remaining harmonic components...

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.

Cyclosporin A-Mediated Activation of Endogenous Neural Precursor Cells Promotes Cognitive Recovery in a Mouse Model of Stroke

Directory of Open Access Journals (Sweden)

Labeeba Nusrat

2018-04-01

Full Text Available Cognitive dysfunction following stroke significantly impacts quality of life and functional independance; yet, despite the prevalence and negative impact of cognitive deficits, post-stroke interventions almost exclusively target motor impairments. As a result, current treatment options are limited in their ability to promote post-stroke cognitive recovery. Cyclosporin A (CsA has been previously shown to improve post-stroke functional recovery of sensorimotor deficits. Interestingly, CsA is a commonly used immunosuppressant and also acts directly on endogenous neural precursor cells (NPCs in the neurogenic regions of the brain (the periventricular region and the dentate gyrus. The immunosuppressive and NPC activation effects are mediated by calcineurin-dependent and calcineurin-independent pathways, respectively. To develop a cognitive stroke model, focal bilateral lesions were induced in the medial prefrontal cortex (mPFC of adult mice using endothelin-1. First, we characterized this stroke model in the acute and chronic phase, using problem-solving and memory-based cognitive tests. mPFC stroke resulted in early and persistent deficits in short-term memory, problem-solving and behavioral flexibility, without affecting anxiety. Second, we investigated the effects of acute and chronic CsA treatment on NPC activation, neuroprotection, and tissue damage. Acute CsA administration post-stroke increased the size of the NPC pool. There was no effect on neurodegeneration or lesion volume. Lastly, we looked at the effects of chronic CsA treatment on cognitive recovery. Long-term CsA administration promoted NPC migration toward the lesion site and rescued cognitive deficits to control levels. This study demonstrates that CsA treatment activates the NPC population, promotes migration of NPCs to the site of injury, and leads to improved cognitive recovery following long-term treatment.

Invited Article: An active terahertz polarization converter employing vanadium dioxide and a metal wire grating in total internal reflection geometry

Science.gov (United States)

Liu, Xudong; Chen, Xuequan; Parrott, Edward P. J.; Han, Chunrui; Humbert, Georges; Crunteanu, Aurelian; Pickwell-MacPherson, Emma

2018-05-01

Active broadband terahertz (THz) polarization manipulation devices are challenging to realize, but also of great demand in broadband terahertz systems. Vanadium dioxide (VO2) shows a promising phase transition for active control of THz waves and provides broadband polarization characteristics when integrated within grating-type structures. We creatively combine a VO2-based grating structure with a total internal reflection (TIR) geometry providing a novel interaction mechanism between the electromagnetic waves and the device, to realize a powerful active broadband THz polarization-controlling device. The device is based on a Si-substrate coated with a VO2 layer and a metal grating structure on top, attached to a prism for generating the TIR condition on the Si-VO2-grating interface. The grating is connected to electrodes for electrically switching the VO2 between its insulating and conducting phases. By properly selecting the incident angle of the THz waves, the grating direction, and the incident polarization state, we first achieved a broadband intensity modulator under a fused silica prism with an average modulation depth of 99.75% in the 0.2-1.1 THz region. Additionally, we realized an active ultra-broadband quarter-wave converter under a Si prism that can be switched between a 45° linear rotator and a quarter wave converter in the 0.8-1.5 THz region. This is the first demonstration of an active quarter-wave converter with ultra-broad bandwidth performance. Our work shows a highly flexible and multifunctional polarization-controlling device for broadband THz applications.

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...

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 ...

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

-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....

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....

Artificial neural network control of sab dc/dc converter

International Nuclear Information System (INIS)

Mahar, M.A.; Abro, M.R.; Larik, A.S.

2009-01-01

The latest development of power semiconductor devices enable the modern power electronic converters to withstand high voltage and high power applications. Power electronic converters are mostly periodic variable structure systems due to their switched operations. The main drawback of these converters is the generation of oscillations which are developed during the operation of the converters under nonlinear situations. To handle these nonlinearities, various researchers have proposed different control techniques. Power electronic designers are devoting in the further development of converter topologies and their control techniques. SAB (Single Active Bridge) DC/DC converter is a new topology recently introduced by Demetriades. This topology is used in high voltage and high power applications. Because of its smart features, SAB converter has recently drawn attention of many researchers. However, during the operation of SAB converter severe oscillations are generated. In this research work, a novel NNC (Neural Network Controller) model is developed for SAB converter to minimize oscillations generated during its operation. NNC is believed to be an advanced nonlinear and robust controller which has the ability to map the nonlinear behaviour in a negligible response time. The performance of SAB converter with NNC is tested under dynamic region by considering the reference voltage variation and duty ratio variation. The SAB converter is implemented and simulated in MATLAB/Simulink. The simulated results are presented. (author)

Lithium converter of reactor neutrinos in antineutrino

International Nuclear Information System (INIS)

Lyutostanskij, Yu.S.; Lyashuk, V.I.

1989-01-01

The questions of developing lithium converter of the reactor neutrons in antineutrino operating at dynamic regime in the scheme with the cycle circulation of the high-purified lithium (by 7 Li isotope) through the converter are considered. The scheme allows to localize the 8 Li β-decay (T 1/2 =0.84 s) in the reservoir near the detector and so to design the hard-spectrum lithium ν-tilde e -source (E max ≅13 MeV) at the distance from the active zone being the soft-spectrum ν-tilde e -source. The expressions for the lithium ν-tilde e flux from the converter, reservoir and conveyance channel are obtained. 9 refs.; 8 figs.; 1 tab

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

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...... be eliminated effectively under steady and dynamic states. Moreover, the proposed strategy exhibits the advantage of not requiring carrier synchronization. It can be utilized in inverters with different types of filter....

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.

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.

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....

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

DEFF Research Database (Denmark)

Pedersen-Bjerggaard, U.; Agerholm-Larsen, B.; 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 relationship prospectively. METHODS: We followed 171 adult outpatients with Type 1 diabetes in a one-year observational study with the recording of severe hypoglycaemia. Participants were characterised by serum ACE activity and ACE genotype and not treated with ACE inhibitors or angiotensin II receptor...... antagonists. RESULTS: There was a positive relationship between serum ACE activity and rate of severe hypoglycaemia with a 2.7 times higher rate in the fourth quartile of ACE activity compared to the first quartile (p=0.0007). A similar relationship was observed for the subset of episodes with coma (2.9 times...

High Voltage Bi-directional Flyback Converter for Capacitive Actuator

DEFF Research Database (Denmark)

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

2013-01-01

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...... in a number of applications. In this paper, the discharging energy efficiency definition is introduced. The proposed converter has been experimentally tested with the film capacitive load and the DEAP actuator, and the experimental results are shown together with the efficiency measurements....

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...

Automatic control in multidrive electrotechnical complexes with semiconductor converters

Science.gov (United States)

Vasilev, B. U.; Mardashov, D. V.

2017-01-01

The frequency convertor and the automatic control system, which can be used in the multi-drive electromechanical system with a few induction motions, are considered. The paper presents the structure of existing modern multi-drive electric drives inverters, namely, electric drives with a total frequency converter and few electric motions, and an electric drive, in which the converter is used for power supply and control of the independent frequency. It was shown that such technical solutions of frequency converters possess a number of drawbacks. The drawbacks are given. It was shown that the control of technological processes using the electric drive of this structure may be provided under very limited conditions, as the energy efficiency and the level of electromagnetic compatibility of electric drives is low. The authors proposed using a multi-inverter structure with an active rectifier in multidrive electric drives with induction motors frequency converters. The application of such frequency converter may solve the problem of electromagnetic compatibility, namely, consumption of sinusoidal currents from the network and the maintenance of a sinusoidal voltage and energy compatibility, namely, consumption of practically active energy from the network. Also, the paper proposes the use of the automatic control system, which by means of a multi-inverter frequency converter provides separate control of drive machines and flexible regulation of technological processes. The authors present oscillograms, which confirm the described characteristics of the developed electrical drive. The possible subsequent ways to improve the multi-motor drives are also described.

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

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...... 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...

Angiotensin converting enzyme 2 activity and human atrial fibrillation: increased plasma angiotensin converting enzyme 2 activity is associated with atrial fibrillation and more advanced left atrial structural remodelling.

Science.gov (United States)

Walters, Tomos E; Kalman, Jonathan M; Patel, Sheila K; Mearns, Megan; Velkoska, Elena; Burrell, Louise M

2017-08-01

Angiotensin converting enzyme 2 (ACE2) is an integral membrane protein whose main action is to degrade angiotensin II. Plasma ACE2 activity is increased in various cardiovascular diseases. We aimed to determine the relationship between plasma ACE2 activity and human atrial fibrillation (AF), and in particular its relationship to left atrial (LA) structural remodelling. One hundred and three participants from a tertiary arrhythmia centre, including 58 with paroxysmal AF (PAF), 20 with persistent AF (PersAF), and 25 controls, underwent clinical evaluation, echocardiographic analysis, and measurement of plasma ACE2 activity. A subgroup of 20 participants underwent invasive LA electroanatomic mapping. Plasma ACE2 activity levels were increased in AF [control 13.3 (9.5-22.3) pmol/min/mL; PAF 16.9 (9.7-27.3) pmol/min/mL; PersAF 22.8 (13.7-33.4) pmol/min/mL, P = 0.006]. Elevated plasma ACE2 was associated with older age, male gender, hypertension and vascular disease, elevated left ventricular (LV) mass, impaired LV diastolic function and advanced atrial disease (P < 0.05 for all). Independent predictors of elevated plasma ACE2 activity were AF (P = 0.04) and vascular disease (P < 0.01). There was a significant relationship between elevated ACE2 activity and low mean LA bipolar voltage (adjusted R2 = 0.22, P = 0.03), a high proportion of complex fractionated electrograms (R2 = 0.32, P = 0.009) and a long LA activation time (R2 = 0.20, P = 0.04). Plasma ACE2 activity is elevated in human AF. Both AF and vascular disease predict elevated plasma ACE2 activity, and elevated plasma ACE2 is significantly associated with more advanced LA structural remodelling. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Non-specific phospholipase C4 mediates response to aluminum toxicity in Arabidopsis thaliana

Directory of Open Access Journals (Sweden)

Přemysl ePejchar

2015-02-01

Full Text Available Aluminum ions (Al have been recognized as a major toxic factor for crop production in acidic soils. The first indication of the Al toxicity in plants is the cessation of root growth, but the mechanism of root growth inhibition is largely unknown. Here we examined the impact of Al on the expression, activity and function of the non-specific phospholipase C4 (NPC4, a plasma membrane-bound isoform of NPC, a member of the plant phospholipase family, in Arabidopsis thaliana.We observed a lower expression of NPC4 using GUS assay and a decreased formation of labeled diacylglycerol, product of NPC activity, using fluorescently labeled phosphatidylcholine as a phospholipase substrate in Arabidopsis WT seedlings treated with AlCl3 for 2 h. The effect on in situ NPC activity persisted for longer Al treatment periods (8, 14 h. Interestingly, in seedlings overexpressing NPC4, the Al-mediated NPC-inhibiting effect was alleviated at 14 h. However, in vitro activity and localization of NPC4 were not affected by Al, thus excluding direct inhibition by Al ions or possible translocation of NPC4 as the mechanisms involved in NPC-inhibiting effect. Furthermore, the growth of tobacco pollen tubes rapidly arrested by Al was partially rescued by the overexpression of AtNPC4 while Arabidopsis npc4 knockout lines were found to be more sensitive to Al stress during long-term exposure of Al at low phosphate conditions.Our observations suggest that NPC4 plays a role in both early and long-term responses to Al stress.

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.

The N domain of somatic angiotensin-converting enzyme negatively regulates ectodomain shedding and catalytic activity

OpenAIRE

Woodman, Zenda L.; Schwager, Sylva L. U.; Redelinghuys, Pierre; Carmona, Adriana K.; Ehlers, Mario R. W.; Sturrock, Edward D.

2005-01-01

sACE (somatic angiotensin-converting enzyme) consists of two homologous, N and C domains, whereas the testis isoenzyme [tACE (testis ACE)] consists of a single C domain. Both isoenzymes are shed from the cell surface by a sheddase activity, although sACE is shed much less efficiently than tACE. We hypothesize that the N domain of sACE plays a regulatory role, by occluding a recognition motif on the C domain required for ectodomain shedding and by influencing the catalytic efficiency. To test ...

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...

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...

Cascaded resonant bridge converters

Science.gov (United States)

Stuart, Thomas A. (Inventor)

1989-01-01

A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

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.

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.

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

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.

Vibration converter with magnetic levitation

Science.gov (United States)

Gladilin, A. V.; Pirogov, V. A.; Golyamina, I. P.; Kulaev, U. V.; Kurbatov, P. A.; Kurbatova, E. P.

2015-05-01

The paper presents a mathematical model, the results of computational and theoretical research, and the feasibility of creating a vibration converter with full magnetic levitation in the suspension of a high-temperature superconductor (HTSC). The axial and radial stability of the active part of the converter is provided by the interaction of the magnetic field of ring-shaped permanent magnets and a hollow cylinder made of the ceramic HTSC material. The force is created by a system of current-carrying coils whose magnetic field is polarized by permanent magnets and interacts with induced currents in the superconducting cylinder. The case of transition to the superconducting state of HTSC material in the field of the permanent magnets (FC mode) is considered. The data confirm the outlook for the proposed technical solutions.

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.

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.

Effect of benazepril and pimobendan on serum angiotensin-converting enzyme activity in dogs.

Science.gov (United States)

King, J N; Christinaz, C; Strehlau, G; Hornfeld, J

2018-06-01

To support their combined use, the objective of the study was to evaluate the effects of benazepril and pimobendan on serum angiotensin-converting enzyme (ACE) activity in dogs. A total of 48 healthy beagle dogs were randomized into four groups (n = 12 per group) in a parallel-group design study: A (control, placebo twice daily (BID)); B (0.5-1.0 mg/kg benazepril once daily (SID) in the morning, placebo in the evening); C (0.25-0.5 mg/kg benazepril BID); D (0.25-0.5 mg/kg benazepril and 0.125-0.25 mg/kg pimobendan, both BID). The test items were administered orally for 15 days. Serum ACE activity was measured on days 1 and 15. Groups B, C and D had significantly lower average serum ACE activity compared to baseline and to the control group, on both days 1 and 15. There were no significant differences in average ACE activity between groups B, C and D. Noninferiority of group C to B was demonstrated. In conclusion, 0.25-0.5 mg/kg benazepril administered BID produced noninferior inhibition of serum ACE activity compared to 0.5-1.0 mg/kg benazepril dosed SID. Pimobendan had no significant effect on benazepril's action on serum ACE activity. The results support the use of benazepril BID in dogs and in combination with pimobendan. © 2018 John Wiley & Sons Ltd.

Artificial heart thermal converter component research and development

International Nuclear Information System (INIS)

Goldowsky, M.; Lehrfeld, D.

1977-01-01

Under U.S. ERDA contract, a radioisotope powered artificial heart system to be used as a replacement for the diseased natural heart is under development by the Westinghouse Advanced Energy Systems Division and Philips Laboratories. A portion of the program activity is in research and development of components for the Stirling cycle thermal converter. Developments in current areas of thermal converter R and D investigation are discussed, including the control system, lubrication system, magnetic shaft coupling, rotary seals, and materials joining

Design and Comparison of Cascaded H-Bridge, Modular Multilevel Converter, and 5-L Active Neutral Point Clamped Topologies for Motor Drive Applications

Energy Technology Data Exchange (ETDEWEB)

Marzoughi, Alinaghi [Virginia Tech, Blacksburg, VA (United States). Center for Power Electronics Systems; Burgos, Rolando [Virginia Tech, Blacksburg, VA (United States). Bradley Dept. of Electrical and Computer Engineering; Boroyevich, Dushan [Virginia Tech, Blacksburg, VA (United States). Bradley Dept. of Electrical and Computer Engineering; Xue, Yaosuo [Siemens Corporate Research, Princeton, NJ (United States). Power Electronics Dept.

2018-03-01

This paper presents the design procedure and comparison of converters currently used in medium-voltage high-power motor drive applications. For this purpose, the cascaded H-bridge (CHB), modular multilevel converter (MMC), and five-level active neutral point clamped (5-L ANPC) topologies are targeted. The design is performed using 1.7-kV insulated gate bipolar transistors (IGBTs) for CHB and MMC converters, and utilizing 3.3- and 4.5-kV IGBTs for 5-L ANPC topology as normally done in industry. The comparison is done between the designed converter topologies at three different voltage levels (4.16, 6.9, and 13.8 kV, with only the first two voltage levels in case of the 5-L ANPC) and two different power levels (3 and 5 MVA), in order to elucidate the dependence of different parameters on voltage and power rating. Finally, the comparison is done from several points of view such as efficiency, capacitive energy storage, semiconductor utilization, parts count (for measure of reliability), and power density.

Disruption in connexin-based communication is associated with intracellular Ca²⁺ signal alterations in astrocytes from Niemann-Pick type C mice.

Directory of Open Access Journals (Sweden)

Pablo J Sáez

Full Text Available Reduced astrocytic gap junctional communication and enhanced hemichannel activity were recently shown to increase astroglial and neuronal vulnerability to neuroinflammation. Moreover, increasing evidence suggests that neuroinflammation plays a pivotal role in the development of Niemann-Pick type C (NPC disease, an autosomal lethal neurodegenerative disorder that is mainly caused by mutations in the NPC1 gene. Therefore, we investigated whether the lack of NPC1 expression in murine astrocytes affects the functional state of gap junction channels and hemichannels. Cultured cortical astrocytes of NPC1 knock-out mice (Npc1⁻/⁻ showed reduced intercellular communication via gap junctions and increased hemichannel activity. Similarly, astrocytes of newborn Npc1⁻/⁻ hippocampal slices presented high hemichannel activity, which was completely abrogated by connexin 43 hemichannel blockers and was resistant to inhibitors of pannexin 1 hemichannels. Npc1⁻/⁻ astrocytes also showed more intracellular Ca²⁺ signal oscillations mediated by functional connexin 43 hemichannels and P2Y₁ receptors. Therefore, Npc1⁻/⁻ astrocytes present features of connexin based channels compatible with those of reactive astrocytes and hemichannels might be a novel therapeutic target to reduce neuroinflammation in NPC disease.

Disruption in connexin-based communication is associated with intracellular Ca²⁺ signal alterations in astrocytes from Niemann-Pick type C mice.

Science.gov (United States)

Sáez, Pablo J; Orellana, Juan A; Vega-Riveros, Natalia; Figueroa, Vania A; Hernández, Diego E; Castro, Juan F; Klein, Andrés D; Jiang, Jean X; Zanlungo, Silvana; Sáez, Juan C

2013-01-01

Reduced astrocytic gap junctional communication and enhanced hemichannel activity were recently shown to increase astroglial and neuronal vulnerability to neuroinflammation. Moreover, increasing evidence suggests that neuroinflammation plays a pivotal role in the development of Niemann-Pick type C (NPC) disease, an autosomal lethal neurodegenerative disorder that is mainly caused by mutations in the NPC1 gene. Therefore, we investigated whether the lack of NPC1 expression in murine astrocytes affects the functional state of gap junction channels and hemichannels. Cultured cortical astrocytes of NPC1 knock-out mice (Npc1⁻/⁻) showed reduced intercellular communication via gap junctions and increased hemichannel activity. Similarly, astrocytes of newborn Npc1⁻/⁻ hippocampal slices presented high hemichannel activity, which was completely abrogated by connexin 43 hemichannel blockers and was resistant to inhibitors of pannexin 1 hemichannels. Npc1⁻/⁻ astrocytes also showed more intracellular Ca²⁺ signal oscillations mediated by functional connexin 43 hemichannels and P2Y₁ receptors. Therefore, Npc1⁻/⁻ astrocytes present features of connexin based channels compatible with those of reactive astrocytes and hemichannels might be a novel therapeutic target to reduce neuroinflammation in NPC disease.

Host-Primed Ebola Virus GP Exposes a Hydrophobic NPC1 Receptor-Binding Pocket, Revealing a Target for Broadly Neutralizing Antibodies.

Science.gov (United States)

Bornholdt, Zachary A; Ndungo, Esther; Fusco, Marnie L; Bale, Shridhar; Flyak, Andrew I; Crowe, James E; Chandran, Kartik; Saphire, Erica Ollmann

2016-02-23

The filovirus surface glycoprotein (GP) mediates viral entry into host cells. Following viral internalization into endosomes, GP is cleaved by host cysteine proteases to expose a receptor-binding site (RBS) that is otherwise hidden from immune surveillance. Here, we present the crystal structure of proteolytically cleaved Ebola virus GP to a resolution of 3.3 Å. We use this structure in conjunction with functional analysis of a large panel of pseudotyped viruses bearing mutant GP proteins to map the Ebola virus GP endosomal RBS at molecular resolution. Our studies indicate that binding of GP to its endosomal receptor Niemann-Pick C1 occurs in two distinct stages: the initial electrostatic interactions are followed by specific interactions with a hydrophobic trough that is exposed on the endosomally cleaved GP1 subunit. Finally, we demonstrate that monoclonal antibodies targeting the filovirus RBS neutralize all known filovirus GPs, making this conserved pocket a promising target for the development of panfilovirus therapeutics. Ebola virus uses its glycoprotein (GP) to enter new host cells. During entry, GP must be cleaved by human enzymes in order for receptor binding to occur. Here, we provide the crystal structure of the cleaved form of Ebola virus GP. We demonstrate that cleavage exposes a site at the top of GP and that this site binds the critical domain C of the receptor, termed Niemann-Pick C1 (NPC1). We perform mutagenesis to find parts of the site essential for binding NPC1 and map distinct roles for an upper, charged crest and lower, hydrophobic trough in cleaved GP. We find that this 3-dimensional site is conserved across the filovirus family and that antibody directed against this site is able to bind cleaved GP from every filovirus tested and neutralize viruses bearing those GPs. Copyright © 2016 Bornholdt et al.

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...

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

OpenAIRE

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.

2016-01-01

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 profi le measured by UPLC MS/MS analysis d...

The Convertible Arbitrage Strategy Analyzed

NARCIS (Netherlands)

Loncarski, I.; Ter Horst, J.R.; Veld, C.H.

2006-01-01

This paper analyzes convertible bond arbitrage on the Canadian market for the period 1998 to 2004.Convertible bond arbitrage is the combination of a long position in convertible bonds and a short position in the underlying stocks. Convertible arbitrage has been one of the most successful strategies

Switched-mode converters (one quadrant)

CERN Document Server

Barrade, P

2006-01-01

Switched-mode converters are DC/DC converters that supply DC loads with a regulated output voltage, and protection against overcurrents and short circuits. These converters are generally fed from an AC network via a transformer and a conventional diode rectifier. Switched-mode converters (one quadrant) are non-reversible converters that allow the feeding of a DC load with unipolar voltage and current. The switched-mode converters presented in this contribution are classified into two families. The first is dedicated to the basic topologies of DC/DC converters, generally used for low- to mid-power applications. As such structures enable only hard commutation processes, the main drawback of such topologies is high commutation losses. A typical multichannel evolution is presented that allows an interesting decrease in these losses. Deduced from this direct DC/DC converter, an evolution is also presented that allows the integration of a transformer into the buck and the buck–boost structure. This enables an int...

Angiotensin-I-converting enzyme and gallium scan in noninvasive evaluation of sarcoidosis

Energy Technology Data Exchange (ETDEWEB)

Nosal, A. (Harbor General Hospital, Torrance, CA); Schleissner, L.A.; Mishkin, F.S.; Lieberman, J.

1979-03-01

Angiotensin-converting enzyme assays and gallium-scan results were obtained from 27 patients with biopsy-proven, clinically active sarcoidosis. Twenty-three of these patients had elevated converting enzyme levels, and 22 had positive gallium-scan results. Three of four patients with normal or borderline-elevated levels of angiotensin-converting enzyme also had positive gallium-scan results. Of 156 nonsarcoid patients (pulmonary and other diseases), 27 were found to have elevated serum converting enzyme levels, and 25 of these had negative gallium-scan results. These results indicate that the combination of an assay of angiotensin-converting enzyme and gallium scan increases diagnostic specificity from 83% to 99% without sacrificing sensitivity. It was concluded that the concurrent use of angiotensin-converting enzyme assay and gallium scan is of value in the diagnosis of sarcoidosis.

Angiotensin-I-converting enzyme and gallium scan in noninvasive evaluation of sarcoidosis

International Nuclear Information System (INIS)

Nosal, A.; Schleissner, L.A.; Mishkin, F.S.; Lieberman, J.

1979-01-01

Angiotensin-converting enzyme assays and gallium-scan results were obtained from 27 patients with biopsy-proven, clinically active sarcoidosis. Twenty-three of these patients had elevated converting enzyme levels, and 22 had positive gallium-scan results. Three of four patients with normal or borderline-elevated levels of angiotensin-converting enzyme also had positive gallium-scan results. Of 156 nonsarcoid patients (pulmonary and other diseases), 27 were found to have elevated serum converting enzyme levels, and 25 of these had negative gallium-scan results. These results indicate that the combination of an assay of angiotensin-converting enzyme and gallium scan increases diagnostic specificity from 83% to 99% without sacrificing sensitivity. It was concluded that the concurrent use of angiotensin-converting enzyme assay and gallium scan is of value in the diagnosis of sarcoidosis

Increased angiotensin-converting enzyme activity in the left ventricle after infarction

Directory of Open Access Journals (Sweden)

V.C.W. Busatto

1997-05-01

Full Text Available An increase in angiotensin-converting enzyme (ACE activity has been observed in the heart after myocardial infarction (MI. Since most studies have been conducted in chronically infarcted individuals exhibiting variable degrees of heart failure, the present study was designed to determine ACE activity in an earlier phase of MI, before heart failure development. MI was produced in 3-month old male Wistar rats by ligation of the anterior branches of the left coronary artery, control rats underwent sham surgery and the animals were studied 7 or 15 days later. Hemodynamic data obtained for the anesthetized animals showed normal values of arterial blood pressure and of end-diastolic pressure in the right and left ventricular cavities of MI rats. Right and left ventricular (RV, LV muscle and scar tissue homogenates were prepared to determine ACE activity in vitro by measuring the velocity of His-Leu release from the synthetic substrate Hyp-His-Leu. ACE activity was corrected to the tissue wet weight and is reported as nmol His-Leu g-1 min-1. No significant change in ACE activity in the RV homogenates was demonstrable. A small nonsignificant increase of ACE activity (11 ± 9%; P0.05 was observed 7 days after MI in the surviving left ventricular muscle. Two weeks after surgery, however, ACE activity was 46 ± 11% (P<0.05 higher in infarcted rats compared to sham-operated rats. The highest ACE activity was demonstrable in the scar tissue homogenate. In rats studied two weeks after surgery, ACE activity in the LV muscle increased from 105 ± 7 nmol His-Leu g-1 min-1 in control hearts to 153 ± 11 nmol His-Leu g-1 min-1 (P<0.05 in the remaining LV muscle of MI rats and to 1051 ± 208 nmol His-Leu g-1 min-1 (P<0.001 in the fibrous scar. These data indicate that ACE activity increased in the heart after infarction before heart failure was demonstrable by hemodynamic measurements. Since the blood vessels of the scar drain to the remaining LV myocardium, the

Buck-Boost/Forward Hybrid Converter for PV Energy Conversion Applications

Directory of Open Access Journals (Sweden)

Sheng-Yu Tseng

2014-01-01

Full Text Available This paper presents a charger and LED lighting (discharger hybrid system with a PV array as its power source for electronic sign indicator applications. The charger adopts buck-boost converter which is operated in constant current mode to charge lead-acid battery and with the perturb and observe method to extract maximum power of PV arrays. Their control algorithms are implemented by microcontroller. Moreover, forward converter with active clamp circuit is operated in voltage regulation condition to drive LED for electronic sign applications. To simplify the circuit structure of the proposed hybrid converter, switches of two converters are integrated with the switch integration technique. With this approach, the proposed hybrid converter has several merits, which are less component counts, lighter weight, smaller size, and higher conversion efficiency. Finally, a prototype of LED driving system under output voltage of 10 V and output power of 20 W has been implemented to verify its feasibility. It is suitable for the electronic sign indicator applications.

Transient Angle Stability Analysis of Grid-Connected Converters with the First-order Active Power Loop

DEFF Research Database (Denmark)

Wu, Heng; Wang, Xiongfei

2018-01-01

. To tackle this challenge, this paper employs the phase portrait to analyze the transient stability of power converters, and it is found that the better transient stability performance can be achieved if the grid-connected converters are controlled as the first-order nonlinear system. Simulations...

Possible identity of IL-8 converting enzyme in human fibroblasts as a cysteine protease.

Science.gov (United States)

Ohashi, Kensaku; Sano, Emiko; Nakaki, Toshio; Naruto, Masanobu

2003-04-01

A converting activity was characterized in human diploid fibroblasts, which secrete 72IL-8 and 77IL-8 in treatment with IFN-beta and poly I: poly C. 77IL-8 was significantly converted to 72IL-8 by a partially purified fraction of the culture supernatant of human diploid fibroblasts. The converting activity, which was temperature-dependent and optimal at pH 6, was completely inhibited by cysteine protease inhibitors, antipain dihydrochloride and E-64, but not by other types of protease inhibitors. These data clearly show that human diploid fibroblasts are capable of processing IL-8 to produce a mature IL-8 and that the putative converting enzyme appears to be a cysteine protease.

Hair growth-promoting effect of Aconiti Ciliare Tuber extract mediated by the activation of Wnt/β-catenin signaling.

Science.gov (United States)

Park, Phil-June; Moon, Byoung-San; Lee, Soung-Hoon; Kim, Su-Na; Kim, Ah-Reum; Kim, Hyung-Jun; Park, Won-Seok; Choi, Kang-Yell; Cho, Eun-Gyung; Lee, Tae Ryong

2012-11-02

The activation of Wnt/β-catenin signaling pathway plays an important role in hair follicle morphogenesis by stimulating bulge stem cells. This study was to obtain the activator of Wnt/β-catenin signaling pathway from natural products and to determine whether this activator can induce anagen hair growth in mice. To identify materials that activate Wnt/β-catenin signaling pathway, 800 natural product extracts were screened using pTOPFlash assay and neural progenitor cell (NPC) differentiation assay. A selected extract was further tested for its effects on alkaline phosphatase (ALP) activity in human immortalized dermal papilla cell (iDPC) and the proliferation in iDPC and immortalized rat vibrissa DPC (RvDP). Finally, hair growth-promoting effects were evaluated in the dorsal skin of C57BL/6 mice. Aconiti Ciliare Tuber (ACT) extract was one of the most active materials in both pTOPFlash and NPC differentiation assays. It promoted the differentiation of NPC cells even under proliferation-stimulating conditions (basic fibroblast growth factor: bFGF). It also increased ALP activity and proliferation of iDPC in dose-dependent manners, and it stimulated the induction of the anagen hair growth in C57BL/6 mice. These results suggest that ACT extract activates the Wnt/β-catenin signaling pathway by enhancing β-catenin transcription and has the potential to promote the induction of hair growth via activation of the stem cell activity of the dermal papilla cells. This is the first report indicating benefits of ACT extract in hair loss prevention by triggering the activation of Wnt/β-catenin signaling pathway and induction of the anagen hair growth in mice. Copyright © 2012 Elsevier Inc. All rights reserved.

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

Impedance Source Power Electronic Converters

DEFF Research Database (Denmark)

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

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...

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. 

dc analysis and design of zero-voltage-switched multi-resonant converters

Science.gov (United States)

Tabisz, Wojciech A.; Lee, Fred C.

Recently introduced multiresonant converters (MRCs) provide zero-voltage switching (ZVS) of both active and passive switches and offer a substantial reduction of transistor voltage stress and an increase of load range, compared to their quasi-resonant converter counterparts. Using the resonant switch concept, a simple, generalized analysis of ZVS MRCs is presented. The conversion ratio and voltage stress characteristics are derived for basic ZVS MRCs, including buck, boost, and buck/boost converters. Based on the analysis, a design procedure that optimizes the selection of resonant elements for maximum conversion efficiency is proposed.

[The changes of serum angiotensin converting enzyme activity in Type 2 diabetes and its vascular complications].

Science.gov (United States)

Wu, H; Qu, S; Zhang, Y; Deng, J; Li, J; Zhou, J

2000-09-01

This investigation was made with reference to the changes of serum angiotensin converting enzyme (SACE) activity in type 2 diabetes and its vascular complications. SACE activity was studied in 127 type 2 diabetic patients and 90 healthy persons by using a spectrophotometric assay. The results showed SACE activity was obviously higher in diabetic patients (459.51 +/- 175.85 U) than in healthy persons (321.14 +/- 121.27 U); SACE activity was significantly higher in type 2 diabetic patients with diabetic nephropathy (548.27 +/- 166.60 U) than in patients without diabetic nephropathy (383.2 +/- 139.00 U), but there was no difference between patients with microalbuminuria and macroalbuminuria; no statistical difference was detected in SACE activity between diabetic patients with diabetic retinopathy (465.64 +/- 178.93 U) and without retinopathy (449.07 +/- 170.04 U); SACE activity was not associated with the course of diabetes, blood pressure, blood lipid and blood glucose. These data suggest that raised SACE activity might only play a role in the initiation of type 2 diabetes and diabetic nephropathy, but not relate to the progress of diabetic nephropathy, the onset of diabetic retinopathy and hypertension.

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...

High-Performance Data Converters

DEFF Research Database (Denmark)

Steensgaard-Madsen, Jesper

-resolution internal D/A converters are required. Unit-element mismatch-shaping D/A converters are analyzed, and the concept of mismatch-shaping is generalized to include scaled-element D/A converters. Several types of scaled-element mismatch-shaping D/A converters are proposed. Simulations show that, when implemented...... 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......-order difference of the output signal from the loop filter's first integrator stage. This technique avoids the need for accurate matching of analog and digital filters that characterizes the MASH topology, and it preserves the signal-band suppression of quantization errors. Simulations show that quantizers...

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...

Multilevel Converter by Cascading Two-Level Three-Phase Voltage Source Converter

Directory of Open Access Journals (Sweden)

Abdullrahman A. Al-Shamma’a

2018-04-01

Full Text Available This paper proposes a topology using isolated, cascaded multilevel voltage source converters (VSCs and employing two-winding magnetic elements for high-power applications. The proposed topology synthesizes 6 two-level, three-phase VSCs, so the power capability of the presented converter is six times the capability of each VSC module. The characteristics of the proposed topology are demonstrated through analyzing its current relationships, voltage relationships and power capability in detail. The power rating is equally shared among the VSC modules without the need for a sharing algorithm; thus, the converter operates as a single three-phase VSC. The comparative analysis with classical neutral-point clamped, flying capacitor and cascaded H-bridge exhibits the superior features of fewer insulated gate bipolar transistors (IGBTs, capacitor requirement and fewer diodes. To validate the theoretical performance of the proposed converter, it is simulated in a MATLAB/Simulink environment and the results are experimentally demonstrated using a laboratory prototype.

A high efficiency photovoltaic module integrated converter with the asymmetrical half-bridge flyback converter

Energy Technology Data Exchange (ETDEWEB)

Kim, Heeje; Kim, Jongrak; Shin, Dongsul [Department of Electrical Engineering, Pusan National University, Jangjeon, Geumjeong, Busan 609-735 (Korea); Kim, Hosung; Lee, Kyungjun [Department of Electrical Engineering, Pusan National University, Jangjeon, Geumjeong, Busan 609-735 (Korea); New and Renewable Energy System Research Center, Korea Electro-technology Research Institute, 28-1, Sungju-dong Changwon-si, Kyungsannam-do, 641-120 (Korea); Kim, Jonghyun; Yoo, Dongwook [New and Renewable Energy System Research Center, Korea Electro-technology Research Institute, 28-1, Sungju-dong Changwon-si, Kyungsannam-do, 641-120 (Korea)

2010-08-15

A module integrated converter (MIC) for a photovoltaic (PV) cell is important part of power conditioning system (PCS). It performs maximum power point tracking of a PV cell to generate the power as much as possible from solar energy. There are several methods for connection between the PV modules and the MICs. In order to avoid partial shading effects, converter-per-module approach was proposed. The MIC that performs maximum power point tracking (MPPT), if it is low efficiency, is no use. The MIC whose output is connected to the output of PV module was proposed for high efficiency. However, there are some problems. In this study, an asymmetrical half-bridge flyback converter is proposed instead of the original flyback converter with same method to solve the problems. The proposed MIC was built to verify the performance. The new topology using soft switching technique showed good performance for the efficiency. At the higher power, the efficiency of the proposed converter is higher than existing converter. (author)

ITER convertible blanket evaluation

International Nuclear Information System (INIS)

Wong, C.P.C.; Cheng, E.

1995-01-01

Proposed International Thermonuclear Experimental Reactor (ITER) convertible blankets were reviewed. Key design difficulties were identified. A new particle filter concept is introduced and key performance parameters estimated. Results show that this particle filter concept can satisfy all of the convertible blanket design requirements except the generic issue of Be blanket lifetime. If the convertible blanket is an acceptable approach for ITER operation, this particle filter option should be a strong candidate

Efficient Wide Range Converters (EWiRaC): A new family of high efficient AC-DC Converters

DEFF Research Database (Denmark)

Petersen, Lars; Andersen, Michael Andreas E.

2006-01-01

The performance in terms of efficiency of the existing power supplies used for PFC is very dependent on the input voltage range. The boost converter is the most commonly used PFC converter because of its simplicity and high efficiency. But, the boost converter as well as other known converters...... suffers a major penalty in efficiency when used at the low end of the voltage range (90VAC) in a universal voltage range application (90-270VAC). This paper addresses this problem by suggesting a new family of converters that effectively reduces the apparent voltage range with a factor of 2 by changing...... the converter topology according to the input voltage. This new converter type has been named: efficient wide range converter (EWiRaC). The performance of the EWiRaC is experimental verified in a universal input range (90-270VAC) application with an output voltage of 185VDC capable of 500W output power. The EWi...

Kinetic considerations of three-way catalysis in automobile exhaust converters

International Nuclear Information System (INIS)

Botas, J.A.; Gutierrez-Ortiz, M.A.; Gonzalez-Marcos, M.P.; Gonzalez-Marcos, J.A.; Gonzalez-Velasco, J.R.

2001-01-01

The activity of three-way catalysts is highly dependent on the reactants present in the automobile exhaust gases (CO, NO x , HC, O 2 , H 2 O, CO 2 , N 2 ) as well as their relative concentration. Thus, the influence of each reactant on the kinetic behavior of the whole mixture makes difficult to establish the accurate kinetics of the system. Activity experiments carried out close to the real operation conditions (GHSV, concentration, etc.) with a Pt/CeO 2 /Al 2 O 3 catalyst supplied data on the CO and HC oxidation and NO reduction reactions in environments formed by different reactant combinations (from binary mixtures to the whole mixture simulating the real conditions at the automobile converter).The obtained results have shown notable variations in the oxidation/reduction mechanisms depending on the presence (or absence) of components in the environment. The presence of water always promoted the three-way activity of the catalyst. The compensation effect applied to the CO, NO and HC conversions confirmed that kinetic expressions obtained with partial mixtures (not very close to the real converter environment) have only limited application for determining the whole kinetic scheme occurring in the automobile converters

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

A Lyapunov Stability Theory-Based Control Strategy for Three-Level Shunt Active Power Filter

Directory of Open Access Journals (Sweden)

Yijia Cao

2017-01-01

Full Text Available The three-phase three-wire neutral-point-clamped shunt active power filter (NPC-SAPF, which most adopts classical closed-loop feedback control methods such as proportional-integral (PI, proportional-resonant (PR and repetitive control, can only output 1st–25th harmonic currents with 10–20 kHz switching frequency. The reason for this is that the controller design must make a compromise between system stability and harmonic current compensation ability under the condition of less than 20 kHz switching frequency. To broaden the bandwidth of the compensation current, a Lyapunov stability theory-based control strategy is presented in this paper for NPC-SAPF. The proposed control law is obtained by constructing the switching function on the basis of the mathematical model and the Lyapunov candidate function, which can avoid introducing closed-loop feedback control and keep the system globally asymptotically stable. By means of the proposed method, the NPC-SAPF has compensation ability for the 1st–50th harmonic currents, the total harmonic distortion (THD and each harmonic content of grid currents satisfy the requirements of IEEE Standard 519-2014. In order to verify the superiority of the proposed control strategy, stability conditions of the proposed strategy and the representative PR controllers are compared. The simulation results in MATLAB/Simulink (MathWorks, Natick, MA, USA and the experimental results obtained on a 6.6 kVA NPC-SAPF laboratory prototype validate the proposed control strategy.

Advances in PV Inverters

DEFF Research Database (Denmark)

Anthon, Alexander

and preferably low complexity leads to new research demands. This is especially true in the field of low cost residential PV inverters where efficiencies are used as major selling arguments. Traditional converter topologies equipped with conventional Silicon based semiconductors to date reach their limitations......, a replacement of only two switching devices per phase leg can greatly reduce the semiconductor losses. The Hybrid-NPC converter can be seen as an attractive and cost competitive alternative to the Silicon Carbide based converter, also allowing to overcome the major drawbacks with the conventional Silicon IGBT...

One-Quadrant Switched-Mode Power Converters

CERN Document Server

Petrocelli, R.

2015-06-15

This article presents the main topics related to one-quadrant power convert- ers. The basic topologies are analysed and a simple methodology to obtain the steady-state output–input voltage ratio is set out. A short discussion of dif- ferent methods to control one-quadrant power converters is presented. Some of the reported derived topologies of one-quadrant power converters are also considered. Some topics related to one-quadrant power converters such as syn- chronous rectification, hard and soft commutation, and interleaved converters are discussed. Finally, a brief introduction to resonant converters is given.

A soft switching with reduced voltage stress ZVT-PWM full-bridge converter

Science.gov (United States)

Sahin, Yakup; Ting, Naim Suleyman; Acar, Fatih

2018-04-01

This paper introduces a novel active snubber cell for soft switching pulse width modulation DC-DC converters. In the proposed converter, the main switch is turned on under zero voltage transition and turned off under zero voltage switching (ZVS). The auxiliary switch is turned on under zero current switching (ZCS) and turned off under zero current transition. The main diode is turned on under ZVS and turned off under ZCS. All of the other semiconductors in the converter are turned on and off with soft switching. There is no extra voltage stress on the semiconductor devices. Besides, the proposed converter has simple structure and ease of control due to common ground. The detailed theoretical analysis of the proposed converter is presented and also verified with both simulation and experimental study at 100 kHz switching frequency and 600 W output power. Furthermore, the efficiency of the proposed converter is 95.7% at nominal power.

Impedance interactions in bidirectional cascaded converter

DEFF Research Database (Denmark)

Tian, Yanjun; Loh, Poh Chiang; Chen, Zhe

2016-01-01

A cascaded converter is built by connecting one elementary converter to another. Output impedance of one converter will therefore interact with input impedance of the other converter. This interaction will change when power flow reverses. To compare this difference, an investigation is performed...

Angiotensin-converting enzyme activity in Cavalier King Charles Spaniels with an ACE gene polymorphism and myxomatous mitral valve disease.

Science.gov (United States)

Meurs, Kathryn M; Olsen, Lisbeth H; Reimann, Maria J; Keene, Bruce W; Atkins, Clarke E; Adin, Darcy; Aona, Brent; Condit, Julia; DeFrancesco, Teresa; Reina-Doreste, Yamir; Stern, Joshua A; Tou, Sandra; Ward, Jessica; Woodruff, Kathleen

2018-02-01

Myxomatous mitral valve disease (MMVD) is the most common heart disease in the dog. It is particularly common in the Cavalier King Charles Spaniel (CKCS) breed and affected dogs are frequently managed with angiotensin-converting enzyme inhibitors (ACE-I). We have previously identified a canine ACE gene polymorphism associated with a decrease in angiotensin-converting enzyme (ACE) activity. The aim of this study was to evaluate for the prevalence of the ACE polymorphism in CKCS with mitral valve disease and to determine whether the presence of the polymorphism is associated with alterations in ACE activity at different stages of cardiac disease. Seventy-three dogs with a diagnosis of mitral valve disease were evaluated and a blood sample was drawn for ACE polymorphism genotyping and ACE activity measurement. Forty-three dogs were homozygous for the ACE polymorphism; five were heterozygous and 25 were homozygous wild type. The mean age and the median severity of disease were not different for dogs with the polymorphism and dogs with the wild-type sequence. The median baseline ACE activity was significantly lower for the ACE polymorphism (27.0 U/l) than the wild-type sequence dogs (31.0 U/l) (P=0.02). Dogs with more severe disease and the ACE polymorphism had significantly lower levels of ACE activity than dogs with the wild-type sequence (P=0.03). The CKCS appears to have a high prevalence of the ACE variant. Dogs with the ACE variant had lower levels of ACE activity even in more advanced mitral valve disease than dogs without the variant. The clinical significance of this finding and its impact on the need for ACE-I in dogs with the polymorphism and heart disease deserves further study.

Matrix metalloproteinase 12 is induced by heterogeneous nuclear ribonucleoprotein K and promotes migration and invasion in nasopharyngeal carcinoma

International Nuclear Information System (INIS)

Chung, I-Che; Li, Hsin-Pai; Chang, Yu-Sun; Chen, Lih-Chyang; Chung, An-Ko; Chao, Mei; Huang, Hsin-Yi; Hsueh, Chuen; Tsang, Ngan-Ming; Chang, Kai-Ping; Liang, Ying

2014-01-01

Overexpression of heterogeneous nuclear ribonucleoprotein K (hnRNP K), a DNA/RNA binding protein, is associated with metastasis in nasopharyngeal carcinoma (NPC). However, the mechanisms underlying hnRNP K-mediated metastasis is unclear. The aim of the present study was to determine the role of matrix metalloproteinase (MMP) in hnRNP K-mediated metastasis in NPC. We studied hnRNP K-regulated MMPs by analyzing the expression profiles of MMP family genes in NPC tissues and hnRNP K-knockdown NPC cells using Affymetrix microarray analysis and quantitative RT-PCR. The association of hnRNP K and MMP12 expression in 82 clinically proven NPC cases was determined by immunohistochemical analysis. The hnRNP K-mediated MMP12 regulation was determined by zymography and Western blot, as well as by promoter, DNA pull-down and chromatin immunoprecipitation (ChIP) assays. The functional role of MMP12 in cell migration and invasion was demonstrated by MMP12-knockdown and the treatment of MMP12-specific inhibitor, PF-356231. MMP12 was overexpressed in NPC tissues, and this high level of expression was significantly correlated with high-level expression of hnRNP K (P = 0.026). The levels of mRNA, protein and enzyme activity of MMP12 were reduced in hnRNP K-knockdown NPC cells. HnRNP K interacting with the region spanning −42 to −33 bp of the transcription start site triggered transcriptional activation of the MMP12 promoter. Furthermore, inhibiting MMP12 by MMP12 knockdown and MMP12-specific inhibitor, PF-356231, significantly reduced the migration and invasion of NPC cells. Overexpression of MMP12 was significantly correlated with hnRNP K in NPC tissues. HnRNP K can induce MMP12 expression and enzyme activity through activating MMP12 promoter, which promotes cell migration and invasion in NPC cells. In vitro experiments suggest that NPC metastasis with high MMP12 expression may be treated with PF-356231. HnRNP K and MMP12 may be potential therapeutic markers for NPC, but

A statistical image analysis framework for pore-free islands derived from heterogeneity distribution of nuclear pore complexes.

Science.gov (United States)

Mimura, Yasuhiro; Takemoto, Satoko; Tachibana, Taro; Ogawa, Yutaka; Nishimura, Masaomi; Yokota, Hideo; Imamoto, Naoko

2017-11-24

Nuclear pore complexes (NPCs) maintain cellular homeostasis by mediating nucleocytoplasmic transport. Although cyclin-dependent kinases (CDKs) regulate NPC assembly in interphase, the location of NPC assembly on the nuclear envelope is not clear. CDKs also regulate the disappearance of pore-free islands, which are nuclear envelope subdomains; this subdomain gradually disappears with increase in homogeneity of the NPC in response to CDK activity. However, a causal relationship between pore-free islands and NPC assembly remains unclear. Here, we elucidated mechanisms underlying NPC assembly from a new perspective by focusing on pore-free islands. We proposed a novel framework for image-based analysis to automatically determine the detailed 'landscape' of pore-free islands from a large quantity of images, leading to the identification of NPC intermediates that appear in pore-free islands with increased frequency in response to CDK activity. Comparison of the spatial distribution between simulated and the observed NPC intermediates within pore-free islands showed that their distribution was spatially biased. These results suggested that the disappearance of pore-free islands is highly related to de novo NPC assembly and indicated the existence of specific regulatory mechanisms for the spatial arrangement of NPC assembly on nuclear envelopes.

Circulating angiotensin-converting enzyme 2 activity in patients with chronic kidney disease without previous history of cardiovascular disease.

Science.gov (United States)

Anguiano, Lidia; Riera, Marta; Pascual, Julio; Valdivielso, José Manuel; Barrios, Clara; Betriu, Angels; Mojal, Sergi; Fernández, Elvira; Soler, María José

2015-07-01

Patients with cardiovascular (CV) disease have an increased circulating angiotensin-converting enzyme 2 (ACE2) activity, but there is little information about changes in ACE2 in chronic kidney disease (CKD) patients without history of CV disease. We examined circulating ACE2 activity in CKD patients at stages 3-5 (CKD3-5) and in dialysis (CKD5D) without any history of CV disease. Circulating ACE2 activity was measured in human ethylenediamine-tetraacetic acid (EDTA)-plasma samples from the NEFRONA study (n = 2572): control group (CONT) (n = 568), CKD3-5 (n = 1458) and CKD5D (n = 546). Different clinical and analytical variables such as gender; age; history of diabetes mellitus (DM), dyslipidemia and hypertension; glycaemic, renal, lipid and anaemia profiles; vitamin D analogues treatment and antihypertensive treatments (angiotensin-converting enzyme inhibitor and angiotensin receptor blockade) were analysed. Circulating ACE2 and ACE activities were measured using modified fluorimetric assay for EDTA-plasma samples, where zinc chloride was added to recover enzymatic activity. In CKD3-5 and CKD5D, significant decrease in circulating ACE2 activity was observed when compared with CONT, but no differences were found between CKD3-5 and CKD5 when performing paired case-control studies. By multivariate linear regression analysis, male gender and advanced age were identified as independent predictors of ACE2 activity in all groups. Diabetes was identified as independent predictor of ACE2 activity in CKD3-5. Significant increase in the activity of circulating ACE was found in CKD3-5 and CKD5D when compared with CONT and in CKD5D when compared with CKD3-5. By multiple regression analysis, female gender and younger age were identified as independent predictors of ACE activity in CONT and CKD3-5. Diabetes was also identified as an independent predictor of ACE activity in CKD3-5 patients. Circulating ACE2 and ACE activities can be measured in human EDTA-plasma samples with zinc

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.

Wireless power charging using point of load controlled high frequency power converters

Science.gov (United States)

Miller, John M.; Campbell, Steven L.; Chambon, Paul H.; Seiber, Larry E.; White, Clifford P.

2015-10-13

An apparatus for wirelessly charging a battery of an electric vehicle is provided with a point of load control. The apparatus includes a base unit for generating a direct current (DC) voltage. The base unit is regulated by a power level controller. One or more point of load converters can be connected to the base unit by a conductor, with each point of load converter comprising a control signal generator that transmits a signal to the power level controller. The output power level of the DC voltage provided by the base unit is controlled by power level controller such that the power level is sufficient to power all active load converters when commanded to do so by any of the active controllers, without generating excessive power that may be otherwise wasted.

Angiotensin-converting enzyme in Spodoptera littoralis: molecular characterization, expression and activity profile during development.

Science.gov (United States)

Lemeire, Els; Vanholme, Bartel; Van Leeuwen, Thomas; Van Camp, John; Smagghe, Guy

2008-02-01

The characterization of the full-length angiotensin-converting enzyme (ACE) cDNA sequence of the lepidopteran Spodoptera littoralis is reported in this study. The predicted open reading frame encodes a 647 amino acids long protein (SlACE) and shows 63.6% identity with the Bombyx mori ACE sequence. A 3D-model, consisting of 26 alpha-helices and three beta-sheets, was predicted for the sequence. SlACE expression was studied in the embryonic, larval and pupal stages of S. littoralis and in different tissues of the last larval stage by reverse-transcribed PCR. This revealed that the gene is expressed throughout the life cycle and especially in brain, gut and fat body tissue of the last stage. These results are in agreement with a role of ACE in the metabolism of neuropeptides and gut hormones. In addition, ACE activity has been studied in more detail during development, making use of a fluorescent assay. High ACE peptidase activity coincides with every transition state, from embryo to larva, from larva to larva and from larva to pupa. A peak value in activity occurs during the early pupal stage. These results indicate the importance of SlACE during metamorphosis and reveal the high correlation of ACE activity with the insect's development, which is regulated by growth and developmental hormones.

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.

Bidirectional dc-to-dc Power Converter

Science.gov (United States)

Griesbach, C. R.

1986-01-01

Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

Status of advanced bremsstrahlung converters

International Nuclear Information System (INIS)

Halbleib, J.A.

1980-01-01

This paper is an attempt to review the somewhat ill-defined area of advanced converter research in a more or less chronological fashion. Section 2 reviews the early B/sub z/ work that was motivated by the CASINO project. More recent work makes liberal use of technology from ICF research using REBs is discussed in Sec. 3. Section 4 discusses possible directions for future research, some of which are being actively pursued at Sandia National Laboratories (SNL) and elsewhere

Hydrogen converters

International Nuclear Information System (INIS)

Mondino, Angel V.

2003-01-01

The National Atomic Energy Commission of Argentina developed a process of 99 Mo production from fission, based on irradiation of uranium aluminide targets with thermal neutrons in the RA-3 reactor of the Ezeiza Atomic Centre. These targets are afterwards dissolved in an alkaline solution, with the consequent liberation of hydrogen as the main gaseous residue. This work deals with the use of a first model of metallic converter and a later prototype of glass converter at laboratory scale, adjusted to the requirements and conditions of the specific redox process. Oxidized copper wires were used, which were reduced to elementary copper at 400 C degrees and then regenerated by oxidation with hot air. Details of the bed structure and the operation conditions are also provided. The equipment required for the assembling in cells is minimal and, taking into account the operation final temperature and the purge with nitrogen, the procedure is totally safe. Finally, the results are extrapolated for the design of a converter to be used in a hot cell. (author)

Electric current - frequency converter

International Nuclear Information System (INIS)

Kumahara, Tadashi; Kinbana, Setsuro.

1967-01-01

Herein disclosed is an improved simple electric current-frequency converter, the input current and output frequency linearity of which is widened to a range of four to five figures while compensating, for temperature. The converter may be used for computor processing and for telemetering the output signals from a nuclear reactor. The converter is an astable multivibrator which includes charging circuits comprising emitter-voltage compensated NPN transistors, a charged voltage detecting circuit of temperature compensated field effect transistors, and a transistor switching circuit for generating switching pulses independent of temperature. The converter exhibited a 0.7% frequency change within a range of 5 - 45 0 C and less than a 0.1% frequency drift after six hours of operation when the input current was maintained constant. (Yamaguchi, T.)

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......DC-DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which......-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc-dc converters are presented and summarized with comparative study of different voltage-boosting techniques....

Optimization of Bi-Directional Flyback Converter for a High Voltage Capacitor Charging Application

DEFF Research Database (Denmark)

Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe

2014-01-01

This paper presents an optimization technique for a flyback converter with a bidirectional energy transfer. The main goal is to optimize the converter for driving an incremental dielectric electro active polymer actuator, which must be charged and discharged from 0 V to 2500 V DC, supplied from...

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 ...

Catalytic converters in the fireplace

International Nuclear Information System (INIS)

Kouki, J.

1995-01-01

In addition to selecting the appropriate means of heating and using dry fuel, the amount of harmful emissions contained by flue gases produced by fireplaces can be reduced by technical means. One such option is to use an oxidising catalytic converter. Tests at TTS Institute's Heating Studies Experimental Station have focused on two such converters (dense and coarse) mounted in light-weight iron heating stoves. The ability of the dense catalytic converter to oxidise carbon monoxide gases proved to be good. The concentration of carbon monoxide in the flue gases was reduced by as much as 90 %. Measurements conducted by VTT (Technical Research Centre of Finland) showed that the conversion of other gases, e.g. of methane, was good. The exhaust resistance caused by the dense converter was so great as to necessitate the mounting of a fluegas evacuation fan in the chimney for the purpose of creating sufficient draught. When relying on natural draught, the dense converter requires a chimney of at least 7 metres and a by-pass connection while the fire is being lit. In addition, the converter will have to be constructed to be less dense and this will mean that it's capability to oxidise non-combusted gases will be reduced. The coarse converter did not impair the draught but it's oxidising property was insufficient. With the tests over, the converter was not observed to have become blocked up by impurities

Targeting APOBEC3A to the viral nucleoprotein complex confers antiviral activity

Directory of Open Access Journals (Sweden)

Strebel Klaus

2007-08-01

Full Text Available Abstract Background APOBEC3 (A3 proteins constitute a family of cytidine deaminases that provide intracellular resistance to retrovirus replication and to transposition of endogenous retroelements. A3A has significant homology to the C-terminus of A3G but has only a single cytidine deaminase active site (CDA, unlike A3G, which has a second N-terminal CDA previously found to be important for Vif sensitivity and virus encapsidation. A3A is packaged into HIV-1 virions but, unlike A3G, does not have antiviral properties. Here, we investigated the reason for the lack of A3A antiviral activity. Results Sequence alignment of A3G and A3A revealed significant homology of A3A to the C-terminal region of A3G. However, while A3G co-purified with detergent-resistant viral nucleoprotein complexes (NPC, virus-associated A3A was highly detergent-sensitive leading us to speculate that the ability to assemble into NPC may be a property conveyed by the A3G N-terminus. To test this model, we constructed an A3G-3A chimeric protein, in which the N-terminal half of A3G was fused to A3A. Interestingly, the A3G-3A chimera was packaged into HIV-1 particles and, unlike A3A, associated with the viral NPC. Furthermore, the A3G-3A chimera displayed strong antiviral activity against HIV-1 and was sensitive to inhibition by HIV-1 Vif. Conclusion Our results suggest that the A3G N-terminal domain carries determinants important for targeting the protein to viral NPCs. Transfer of this domain to A3A results in A3A targeting to viral NPCs and confers antiviral activity.

Spectrometric analog-to-digital converter

International Nuclear Information System (INIS)

Ormandzhiev, S.I.; Jordanov, V.T.

1988-01-01

Converter of digit-by-digit counterbalancing with slipping dial with number of channels equal to total number of states of the main digital-to-analog converter of digit-by-digit counterbalancing systems is presented. Algorithm for selection of digital-to-analog converters, which must be used by means of computer is suggested

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.

Improving Power Converter Reliability

DEFF Research Database (Denmark)

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

2014-01-01

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......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...... is measured in a wind power converter at a low fundamental frequency. To illustrate more, the test method as well as the performance of the measurement circuit are also presented. This measurement is also useful to indicate failure mechanisms such as bond wire lift-off and solder layer degradation...

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...... of the second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or forcing substantially 0 degree phase shift, between corresponding resonant voltage waveforms of the first...

Reversing flow catalytic converter for a natural gas/diesel dual fuel engine

Energy Technology Data Exchange (ETDEWEB)

Liu, E.; Checkel, M.D. [Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering; Hayes, R.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Alberta Univ., Edmonton, AB (Canada). Dept. of Mechanical Engineering; Zheng, M.; Mirosh, E. [Alternative Fuel Systems Inc., Calgary, AB (Canada)

2001-07-01

An experimental and modelling study was performed for a reverse flow catalytic converter attached to a natural gas/diesel dual fuel engine. The catalytic converter had a segmented ceramic monolith honeycomb substrate and a catalytic washcoat containing a predominantly palladium catalyst. A one-dimensional single channel model was used to simulate the operation of the converter. The kinetics of the CO and methane oxidation followed first-order behaviour. The activation energy for the oxidation of methane showed a change with temperature, dropping from a value of 129 to 35 kJ/mol at a temperature of 874 K. The reverse flow converter was able to achieve high reactor temperature under conditions of low inlet gas temperature, provided that the initial reactor temperature was sufficiently high. (author)

ZIF-67 incorporated with carbon derived from pomelo peels: A highly efficient bifunctional catalyst for oxygen reduction/evolution reactions

Energy Technology Data Exchange (ETDEWEB)

Wang, Hao; Yin, Feng-Xiang; Chen, Biao-Hua; He, Xiao-Bo; Lv, Peng-Liang; Ye, Cai-Yun; Liu, Di-Jia

2017-05-01

Developing carbon catalyst materials using natural, abundant and renewable resources as precursors plays an increasingly important role in clean energy generation and environmental protection. In this work, N-doped pomelo-peel-derived carbon (NPC) materials were prepared using a widely available food waste-pomelo peels and melamine. The synthetic NPC exhibits well-defined porosities and a highly doped-N content (e.g. 6.38 at% for NPC-2), therefore affords excellent oxygen reduction reaction (ORR) catalytic activities in alkaline electrolytes. NPC was further integrated with ZIF-67 to form ZIF-67@NPC hybrids through solvothermal reactions. The hybrid catalysts show substantially enhanced ORR catalytic activities comparable to that of commercial 20 wa Pt/C. Furthermore, the catalysts also exhibit excellent oxygen evolution reaction (OER) catalytic activities. Among all prepared ZIF-67@NPC hybrids, the optimal composition with ZIF-67 to NPC ratio of 2:1 exhibits the best ORR and OER bifunctional catalytic performance and the smallest Delta E (E-OER@10 mA cm(-2)-E-ORR@-1 mA cm(-2)) value of 0.79 V. The catalyst also demonstrated desirable 4-electron transfer pathways and superior catalytic stabilities. The Co-N-4 in ZIF-67, electrochemical active surface area, and the strong interactions between ZIF-67 and NPC are attributed as the main contributors to the bifunctional catalytic activities. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activities and stabilities; consequently, this hybrid catalyst is among the best of the reported bifunctional electrocatalysts and is promising for use in metal-air batteries and fuel cells. (C) 2016 Elsevier B.V. All rights reserved.

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.

Dual Converter Fed Open-End Transformer Topology with Parallel Converters and Integrated Magnetics

DEFF Research Database (Denmark)

Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand; Teodorescu, Remus

2016-01-01

that flows between the parallel interleaved VSCs. An integrated inductor is proposed which suppresses the circulating current in both the converter groups. In addition, the functionality of the line filter inductor is also integrated. Flux in various parts of the integrated inductor is analyzed and a design......A converter system for high power applications, connected to a medium-voltage network using a stepup transformer, is presented in this paper. The converterside winding of the transformer is configured as an openend and both the ends of the windings are fed from two different converter groups. Each...... procedure is also described. The volume and the losses of the proposed solution are compared with that of the state-of-art solution. The control of the proposed converter system is also discussed. The analysis has been verified by the simulation and experimental results....

Evaluation and optimization of the bandwidth of static converters: application to multi-cell converters; Evaluation et optimisation de la bande passante des convertisseurs statiques

Energy Technology Data Exchange (ETDEWEB)

Aime, M.

2003-11-15

Thanks to the technological progress achieved in the field of power electronics, the use of static converters has spread to new applications. In particular, some applications such as active filtering or the supply of special AC machines require power converters having good dynamic performances. The subject of this thesis is to evaluate systematically the dynamic performances of multi-cell converters, and then to optimize these performances. This document is organized in four chapters. The first one summarizes the main multilevel converter structures, and some control strategies dedicated to these structures. The second chapter presents the evaluation criteria chosen to quantify the dynamic performances of static converters. These criteria are then used to compare the performances obtained with two different PWM strategies. An optimized strategy which results from a trade-off between the two former strategies is then introduced. The third chapter shows a new control strategy of multi-cell voltage source converters. This new strategy enables to control the peak current at a fixed switching frequency. The operation of this controller is explained, and the results obtained by digital simulations are presented and discussed. The fourth chapter deals with the experimental achievement of the peak current control. In particular, the implementation of the control algorithm within a FPGA is demonstrated. Finally, the conclusion of this thesis presents some orientations for further developments, in order to improve the current control strategy and to widen its field of applications. (author)

Proportional-Resonant Controllers. A New Breed of Controllers Suitable for Grid-Connected Voltage-Source Converters

DEFF Research Database (Denmark)

Teodorescu, Remus; Blaabjerg, Frede

2004-01-01

This paper is describing the recently introduced proportional-resonant (PR) controllers and their suitability for grid-connected converters current control. It is shown that the known shortcomings associated with PI controllers like steady - state error for single-phase converters and the need...... of decoupling for three-phase converters can be alleviated. Additionally, selective harmonic compensation is also possible with PR controllers. Suggested control-diagrams for three-phase grid converters and active filters are also presented. A practical application of PR current control for a photovoltaic (PV...

A Two-Phase Buck Converter with Optimum Phase Selection for Low Power Applications

OpenAIRE

Yeago, Taylor Craig

2015-01-01

Power consumption of smart cameras varies significantly between sleep mode and active mode, and a smart camera operates in sleep mode for 80 ��" 90% of time for typical use. To prolong the battery life of smart cameras, it is essential to increase the power converter efficiency for light load, while being able to manage heavy load. The power stage of traditional buck converter is optimized for maximum load, at the cost of light-load efficiency. Wei proposed a multiphase buck converter incorpo...

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

Directory of Open Access Journals (Sweden)

Maira R. Segura-Campos

2013-01-01

Full Text Available 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 <1 kDa fractions were selected for further fractionation by gel filtration chromatography. ACE inhibitory activity (% ranged from 22.66 to 45.96% with the 5–10 kDa ultrafiltered fraction and from 36.91 to 55.83% with the <1 kDa ultrafiltered fraction. The highest ACE inhibitory activity was observed in F2 ( μg/mL from the 5–10 kDa fraction and F1 ( μg/mL from the <1 kDa fraction. ACE inhibitory fractions from 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.

A control strategy for multi-functional converter to improve grid power quality

DEFF Research Database (Denmark)

Li, Fei; Wang, Xiongfei; Chen, Zhe

2011-01-01

The extensive use of converter-interfacing distributed energy resources (DER), combined with a large amount of nonlinear and unbalanced loads connected to the distribution power system, has led to power quality problem. This paper proposes a control strategy for a three-phase four-leg multi-funct......) for multi-functional converter is described. Simulation and hardware in the loop real time test results carried on a three-phase four-wire distributed generation system illustrate the effectiveness of the proposed control strategy.......The extensive use of converter-interfacing distributed energy resources (DER), combined with a large amount of nonlinear and unbalanced loads connected to the distribution power system, has led to power quality problem. This paper proposes a control strategy for a three-phase four-leg multi......-functional converter which can compensate reactive power, harmonic currents, unbalance, and neutral current simultaneously under distorted voltage conditions, besides the active power exchange. The capacity of the converter is taken into account. The proposed control strategy based on synchronous reference frame (SRF...

Characterization of angiotensin-converting enzyme inhibitory activity of fermented milk produced by Lactobacillus helveticus.

Science.gov (United States)

Chen, Yongfu; Li, Changkun; Xue, Jiangang; Kwok, Lai-yu; Yang, Jie; Zhang, Heping; Menghe, Bilige

2015-08-01

Hypertension affects up to 30% of the adult population in most countries. It is a known risk factor for cardiovascular diseases, including coronary heart disease, peripheral artery disease, and stroke. Owing to the increased health awareness of consumers, the application of angiotensin-converting enzyme (ACE)-inhibitory peptides produced by Lactobacillushelveticus to prevent or control high blood pressure has drawn wide attention. A total of 59 L. helveticus strains were isolated from traditional fermented dairy products and the ACE-inhibitory activity of the fermented milks produced with the isolated microorganisms was assayed. The ACE-inhibitory activity of 38 L. helveticus strains was more than 50%, and 3 strains (IMAU80872, IMAU80852, and IMAU80851) expressing the highest ACE-inhibitory activity were selected for further studies. Particularly, the gastrointestinal protease tolerance and thermostability of the ACE-inhibitory activity in the fermented milks were assessed. Based on these 2 criteria, IMAU80872 was found to be superior over the other 2 strains. Furthermore, IMAU80872 exhibited a high in vitro ACE-inhibitory activity at the following fermentation conditions: fermentation temperature at 40°C, inoculation concentration of 1×10(6) cfu/mL, and fermentation for 18h. Finally, by using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry analysis, we observed changes of the metabolome along the milk fermentation process of IMAU80872. Furthermore, 6 peptides were identified, which might have ACE-inhibitory activity. In conclusion, we identified a novel ACE-inhibitory L. helveticus strain suitable for the production of fermented milk or other functional dairy products. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Antiglaucomatous effects of the activation of intrinsic Angiotensin-converting enzyme 2.

Science.gov (United States)

Foureaux, Giselle; Nogueira, José C; Nogueira, Bárbara S; Fulgêncio, Gustavo O; Menezes, Gustavo B; Fernandes, Simone O A; Cardoso, Valbert N; Fernandes, Renata S; Oliveira, Gabriel P; Franca, Juçara R; Faraco, André A G; Raizada, Mohan K; Ferreira, Anderson J

2013-06-21

To evaluate the effects of the activation of endogenous angiotensin-converting enzyme 2 (ACE2) using the compound diminazene aceturate (DIZE) in an experimental model of glaucoma in Wistar rats. DIZE (1 mg/kg) was administered daily, either systemically or topically, and the IOP was measured weekly. To examine the role of the Mas receptor in the effects of DIZE, the Ang-(1-7) antagonist A-779 was co-administered. Drainage of the aqueous humor was evaluated by using scintigraphy. The analysis of ACE2 expression by immunohistochemistry and the counting of retinal ganglion cells (RGCs) were performed in histologic sections. Additionally, the nerve fiber structure was evaluated by transmission electron microscopy. The systemic administration and topical administration (in the form of eye drops) of DIZE increased the ACE2 expression in the eyes and significantly decreased the IOP of glaucomatous rats without changing the blood pressure. Importantly, this IOP-lowering action of DIZE was similar to the effects of dorzolamide. The antiglaucomatous effects of DIZE were blocked by A-779. Histologic analysis revealed that the reduction in the number of RGCs and the increase in the expression of caspase-3 in the RGC layer in glaucomatous animals were prevented by DIZE. This compound also prevented alterations in the cytoplasm of axons in glaucomatous rats. In addition to these neuroprotective effects, DIZE facilitated the drainage of the aqueous humor. Our results evidence the pathophysiologic relevance of the ocular ACE2/Ang-(1-7)/Mas axis of the renin-angiotensin system and, importantly, indicate that the activation of intrinsic ACE2 is a potential therapeutic strategy to treat glaucoma.

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.

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.

A resonant dc-dc power converter assembly

OpenAIRE

Madsen, Mickey Pierre

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 second resonant DC-DC power converter are configured for magnetically coupling the first and second resonant DC-DC power converters to each other to forcing substantially 180 degrees phase shift, or fo...

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 ...

An improved control scheme based in droop characteristic for microgrid converters

Energy Technology Data Exchange (ETDEWEB)

Arboleya, P.; Diaz, D.; Guerrero, J.M.; Garcia, P.; Briz, F.; Gonzalez-Moran, C.; Gomez Aleixandre, J. [University of Oviedo, Electrical Engineering Department, 33204 Gijon, Asturias (Spain)

2010-10-15

In the present work, an improved version of the conventional-droop control for microgrid converter is presented. The modifications added to the control are based on a feed-forward current control that allows the converter to work in several modes, both when it is grid connected or in island. The use of this control represents the main contribution of this paper, permitting the inverter to work as a grid supporting source or ancillary services provider when it works grid connected. In this mode the converter varies the injected active and reactive power with the variation of voltage module and frequency using the same main control loop as when it is working in island mode. (author)

High Current, Low Voltage Power Converter [20kA, 6V] LHC Converter Prototype

CERN Document Server

Jørgensen, H E; Dupaquier, A; Fernqvist, G

1998-01-01

The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filter...

Loss of connective tissue growth factor as an unfavorable prognosis factor activates miR-18b by PI3K/AKT/C-Jun and C-Myc and promotes cell growth in nasopharyngeal carcinoma.

Science.gov (United States)

Yu, X; Zhen, Y; Yang, H; Wang, H; Zhou, Y; Wang, E; Marincola, F M; Mai, C; Chen, Y; Wei, H; Song, Y; Lyu, X; Ye, Y; Cai, L; Wu, Q; Zhao, M; Hua, S; Fu, Q; Zhang, Y; Yao, K; Liu, Z; Li, X; Fang, W

2013-05-16

Connective tissue growth factor (CTGF) has different roles in different types of cancer. However, the involvement and molecular basis of CTGF in tumor progression and prognosis of human nasopharyngeal carcinoma (NPC) have almost never been reported. In this study, we observed that downregulated CTGF expression was significantly associated with NPC progression and poor prognosis. Knockdown of CTGF markedly elevated the ability of cell proliferation in vivo and in vitro. Subsequently, we discovered that the reduction of CTGF increased the expression of miR-18b, an oncomir-promoting cell proliferation. Further, we discovered that attenuated CTGF-mediated upregulation of miR-18b was dependent on the increased binding of transcription factors Jun proto-oncogene (C-Jun) and v-Myc myelocytomatosis viral oncogene homolog (C-Myc) to miR-18b promoter region via phosphoinositide 3-kinase (PI3K)/AKT pathway. Finally, we further found that miR-18b directly suppressed the expression of CTGF in NPC. In clinical fresh specimens, miR-18b was widely overexpressed and inversely correlated with CTGF expression in NPC. Our studies are the first to demonstrate that reduced CTGF as an unfavorable prognosis factor mediates the activation of miR-18b, an oncomir directly suppresses CTGF expression, by PI3K/AKT/C-Jun and C-Myc and promotes cell growth of NPC.

Multi-Port High Voltage Gain Modular Power Converter for Offshore Wind Farms

Directory of Open Access Journals (Sweden)

Sen Song

2018-06-01

Full Text Available In high voltage direct current (HVDC power transmission of offshore wind power systems, DC/DC converters are applied to transfer power from wind generators to HVDC terminals, and they play a crucial role in providing a high voltage gain, high efficiency, and high fault tolerance. This paper introduces an innovative multi-port DC/DC converter with multiple modules connected in a scalable matrix configuration, presenting an ultra-high voltage step-up ratio and low voltage/current rating of components simultaneously. Additionally, thanks to the adoption of active clamping current-fed push–pull (CFPP converters as sub-modules (SMs, soft-switching is obtained for all power switches, and the currents of series-connected CFPP converters are auto-balanced, which significantly reduce switching losses and control complexity. Furthermore, owing to the expandable matrix structure, the output voltage and power of a modular converter can be controlled by those of a single SM, or by adjusting the column and row numbers of the matrix. High control flexibility improves fault tolerance. Moreover, due to the flexible control, the proposed converter can transfer power directly from multiple ports to HVDC terminals without bus cable. In this paper, the design of the proposed converter is introduced, and its functions are illustrated by simulation results.

Two-inductor boost and buck converters

Science.gov (United States)

White, J. L.; Muldoon, W. J.

The derivation, analysis and design of a coupled inductor boost converter is presented. Aspects of the qualitative ac behavior of coupled inductor converters are discussed. Considerations for the design of the magnetics for such converters are addressed.

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...

A new concept of thermionic converter

International Nuclear Information System (INIS)

Musa, G.

1978-10-01

The parameters of a new type of thermionic converter which has a number of concentric electrodes, is computed. The obtained theoretical efficiency of this new type of converter is nearly the efficiency of the ideal thermionic converter. The obtained results are explained by the reduction of the radiation loss from the emitter due to the electrode configuration. Efficiencies as high as 20% are expected from this type of converter now in construction. (author)

Advanced DC/DC converters

CERN Document Server

Luo, Fang Lin

2003-01-01

DC/DC conversion techniques have undergone rapid development in recent decades. With the pioneering work of these authors, DC/DC converters have now moved into their sixth generation. This book offers a concise, practical presentation of DC/DC converters, summarizing the spectrum of conversion tecnologies and presentingmany new ideas and more than 100 new topologies. Nowhere else in the literature are DC/DC converters so logically sorted and systematically introduced, and nowhere else can readers find detailed information on prototype topologies that represent a major contribution to modern power engineering. More than 320 figures, 60 tables, and 500 formulae facilitate understand and provide precise data.

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...

Amplitude-to-frequency converter of radioisotope instruments

International Nuclear Information System (INIS)

Demchenkov, V.P.; Korobkov, I.N.

1988-01-01

An amplitude-to-frequency converter designed for signal processing of radioisotope relay devices is descibed. The basic elements of the converter are a scaling amplifier, an analog-to-digital converter, a code-to-frequency converter, a null-organ, a delay unit and a clock-pulse generator. The designed amplitude-to-frequency converter takes into account a prior information about the signal shape of the energy spectrum. The converter processes input pulses of 0.10 V amplitude and duration more than 2μs. The energy channel number is 64

Optimal Isolation Control of Three-Port Active Converters as a Combined Charger for Electric Vehicles

Directory of Open Access Journals (Sweden)

Zhixiang Ling

2016-09-01

Full Text Available The three-port converter has three H-bridge ports that can interface with three different energy sources and offers the advantages of flexible power transmission, galvanic isolation ability and high power density. The three-port full-bridge converter can be used in electric vehicles as a combined charger that consists of a battery charger and a DC-DC converter. Power transfer occurs between two ports while the third port is isolated, i.e., the average power is zero. The purpose of this paper is to apply an optimal phase shift strategy in isolation control and provide a detailed comparison between traditional phase shift control and optimal phase shift control under the proposed isolation control scheme, including comparison of the zero-voltage-switching range and the root mean square current for the two methods. Based on this analysis, the optimal parameters are selected. The results of simulations and experiments are given to verify the advantages of dual-phase-shift control in isolation control.

Design and Implementation of Battery Charger with Power Factor Correction Using Sepic Converter and Full-bridge DC-DC Converter

OpenAIRE

Efendi, Moh. Zaenal; Windarko, Novie Ayub; Amir, Moh. Faisal

2013-01-01

This paper presents a design and implementation of a converter which has a high power factor for battery charger application. The converter is a combination of a SEPIC converter and a full-bridge DC-DC converter connected in two stages of series circuit. The SEPIC converter works in discontinuous conduction mode and it serves as a power factor corrector so that the shape of input current waveform follows the shape of input voltage waveform. The full-bridge DC-DC converter serves as a regulato...

Multi-functional Converter with Integrated Motor Control, Battery Charging and Active Module Balancing for Electric Vehicular Application

DEFF Research Database (Denmark)

Mathe, Laszlo; Schaltz, Erik; Teodorescu, Remus

2014-01-01

, weight and volume in comparison with other Li-Ion based chemistries. The control of the energy flow has been done through a Modular Multilevel Converter (MMC), which has demonstrated advantages over 2 level converters in terms of efficiency, fault tolerant operation, flexible operation modes. It has been...

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....

Three-phase Resonant DC-link Converter

OpenAIRE

Munk-Nielsen, Stig

1997-01-01

The purpose of the project is to develop a three-phase resonant converter suitable for standard speed drives. The motivation for working with resonant converters is found in the problem of the standard converter type used today. In standard converter type Pulse Width Modulated-Voltage Source Inverter, PWM-VSI, the switches are subject to high current and voltage stress during switching, which causes losses. The fast switching of modern switches reduces switching losses. Unfortunately this pro...

Salinomycin inhibits proliferation and induces apoptosis of human nasopharyngeal carcinoma cell in vitro and suppresses tumor growth in vivo

Energy Technology Data Exchange (ETDEWEB)

Wu, Danxin; Zhang, Yu; Huang, Jie; Fan, Zirong; Shi, Fengrong; Wang, Senming, E-mail: wsenming@126.com

2014-01-10

Highlight: •We first evaluated the effect of salinomycin on nasopharyngeal carcinoma (NPC). •Salinomycin could inhibit Wnt/β-catenin signaling and induce apoptosis in NPC. •So salinomycin may be a good potential candidate for the chemotherapy of NPC. -- Abstract: Salinomycin (Sal) is a polyether ionophore antibiotic that has recently been shown to induce cell death in various human cancer cells. However, whether salinomycin plays a functional role in nasopharyngeal carcinoma (NPC) has not been determined to date. The present study investigated the chemotherapeutic efficacy of salinomycin and its molecular mechanisms of action in NPC cells. Salinomycin efficiently inhibited proliferation and invasion of 3 NPC cell lines (CNE-1, CNE-2, and CNE-2/DDP) and activated a extensive apoptotic process that is accompanied by activation of caspase-3 and caspase-9, and decreased mitochondrial membrane potential. Meanwhile, the protein expression level of the Wnt coreceptor lipoprotein receptor related protein 6 (LRP6) and β-catenin was down-regulated, which showed that the Wnt/β-catenin signaling was involved in salinomycin-induced apoptosis of NPC cells. In a nude mouse NPC xenograft model, the anti-tumor effect of salinomycin was associated with the downregulation of β-catenin expression. The present study demonstrated that salinomycin can effectively inhibit proliferation and invasion, and induce apoptosis of NPC cells in vitro and inhibit tumor growth in vivo, probably via the inhibition of Wnt/β-catenin signaling, suggesting salinomycin as a potential candidate for the chemotherapy of NPC.

Design and Implementation of Battery Charger with Power Factor Correction using Sepic Converter and Full-bridge DC-DC Converter

Directory of Open Access Journals (Sweden)

Moh. Zaenal Efendi

2013-12-01

Full Text Available This paper presents a design and implementation of a converter which has a high power factor for battery charger application. The converter is a combination of a SEPIC converter and a full-bridge DC-DC converter connected in two stages of series circuit. The SEPIC converter works in discontinuous conduction mode and it serves as a power factor corrector so that the shape of input current waveform follows the shape of input voltage waveform. The full-bridge DC-DC converter serves as a regulator of output voltage and operates at continuous conduction mode. The experimental results show that the power factor of this converter system can be achieved up to 0.96.

Full range ZVS DC-DC converter

International Nuclear Information System (INIS)

Upadhyay, Rinki; Badapanda, M.K.; Hannurkar, P.R.

2011-01-01

A 500 V, 24 Amp DC-DC converter with digital signal processor (DSP) based control and protection has been designed, fabricated and tested. Its power circuit consists of IGBT based single phase inverter bridge, ferrite transformer and diode rectifier. All IGBTs in the inverter bridge are operated in zero voltage switching (ZVS) mode to minimize switching losses thereby increasing the efficiency of the converter significantly. The efficiency of this converter is measured to be greater than 97% at full load. In a conventional full bridge inverter, typically ZVS is achieved under full load condition while at light load ZVS is lost. An auxiliary LC circuit has been intentionally incorporated in this converter to achieve ZVS even at light loaded conditions. Detailed simulation of the converter circuit is carried out and crucial waveforms have been presented in this paper. Microchip make dsPIC30F2020 DSP is employed to provide phase shifted PWMs to IGBTs in the inverter bridge. All the crucial parameters are also monitored by this DSP and in case of any unfavorable conditions, the converter is tripped off. Suitable experiments were carried out in this DC-DC converter under different loaded conditions and a close match between the simulated and experimental results were obtained. Such DC-DC converters can be connected in series or parallel for the development of solid state modular power supplies for various applications. (author)

Research & Implementation of AC - DC Converter with High Power Factor & High Efficiency

Directory of Open Access Journals (Sweden)

Hsiou-Hsian Nien

2014-05-01

Full Text Available In this paper, we design and develop a high power factor, high efficiency two-stage AC - DC power converter. This paper proposes a two-stage AC - DC power converter. The first stage is boost active power factor correction circuit. The latter stage is near constant frequency LLC resonant converter. In addition to traditional LLC high efficiency advantages, light-load conversion efficiency of this power converter can be improved. And it possesses high power factor and near constant frequency operating characteristics, can significantly reduce the electromagnetic interference. This paper first discusses the main structure and control manner of power factor correction circuit. And then by the LLC resonant converter equivalent model proceed to circuit analysis to determine the important parameters of the converter circuit elements. Then design a variable frequency resonant tank. The resonant frequency can change automatically on the basis of the load to reach near constant frequency operation and a purpose of high efficiency. Finally, actually design and produce an AC – DC power converter with output of 190W to verify the characteristics and feasibility of this converter. The experimental results show that in a very light load (9.5 W the efficiency is as high as 81%, the highest efficiency of 88% (90 W. Full load efficiency is 87%. At 19 W ~ 190 W power changes, the operating frequency change is only 0.4 kHz (AC 110 V and 0.3 kHz (AC 220 V.

Open-circuit fault detection and tolerant operation for a parallel-connected SAB DC-DC converter

DEFF Research Database (Denmark)

Park, Kiwoo; Chen, Zhe

2014-01-01

This paper presents an open-circuit fault detection method and its tolerant control strategy for a Parallel-Connected Single Active Bridge (PCSAB) dc-dc converter. The structural and operational characteristics of the PCSAB converter lead to several advantages especially for high power applicatio...

High-frequency matrix converter with square wave input

Science.gov (United States)

Carr, Joseph Alexander; Balda, Juan Carlos

2015-03-31

A device for producing an alternating current output voltage from a high-frequency, square-wave input voltage comprising, high-frequency, square-wave input a matrix converter and a control system. The matrix converter comprises a plurality of electrical switches. The high-frequency input and the matrix converter are electrically connected to each other. The control system is connected to each switch of the matrix converter. The control system is electrically connected to the input of the matrix converter. The control system is configured to operate each electrical switch of the matrix converter converting a high-frequency, square-wave input voltage across the first input port of the matrix converter and the second input port of the matrix converter to an alternating current output voltage at the output of the matrix converter.

Study on the Control Algorithm of Two-Stage DC-DC Converter for Electric Vehicles

Directory of Open Access Journals (Sweden)

Changhao Piao

2014-01-01

Full Text Available The fast response, high efficiency, and good reliability are very important characteristics to electric vehicles (EVs dc/dc converters. Two-stage dc-dc converter is a kind of dc-dc topologies that can offer those characteristics to EVs. Presently, nonlinear control is an active area of research in the field of the control algorithm of dc-dc converters. However, very few papers research on two-stage converter for EVs. In this paper, a fixed switching frequency sliding mode (FSFSM controller and double-integral sliding mode (DISM controller for two-stage dc-dc converter are proposed. And a conventional linear control (lag is chosen as the comparison. The performances of the proposed FSFSM controller are compared with those obtained by the lag controller. In consequence, the satisfactory simulation and experiment results show that the FSFSM controller is capable of offering good large-signal operations with fast dynamical responses to the converter. At last, some other simulation results are presented to prove that the DISM controller is a promising method for the converter to eliminate the steady-state error.

A novel series-resonant converter topology

NARCIS (Netherlands)

Tilgenkamp, N.V.; Haan, de S.W.H.; Huisman, H.

1987-01-01

A converter topology based on the principles of seriesresonant (SR) power conversion is described in which the input and output of this converter have one terminal in common, and the transformer is omitted. Both the underlying theory and associated waveforms are presented. The converter is suitable

The application of standardized control and interface circuits to three dc to dc power converters.

Science.gov (United States)

Yu, Y.; Biess, J. J.; Schoenfeld, A. D.; Lalli, V. R.

1973-01-01

Standardized control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the series-switching buck regulator, and the pulse-modulated parallel inverter. The two-loop ASDTIC regulation control concept was implemented by using a common analog control signal processor and a novel digital control signal processor. This resulted in control circuit standardization and superior static and dynamic performance of the three dc-to-dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.

Parametric study of laser photovoltaic energy converters

Science.gov (United States)

Walker, G. H.; Heinbockel, J. H.

1987-01-01

Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

Dividend-Protected Convertible Bonds and the Disappearance

OpenAIRE

Bruce D. Grundy; Patrick Verwijmeren

2012-01-01

Firms have not historically called their convertible bonds as soon as they could force conversion. Various explanations for the delay rely on the size of the dividends that bondholders forgo so long as they do not convert. We investigate an important change in convertible security design, namely that more than 95 percent of recent convertible bond issues are dividend-protected. Dividend protection means that the conversion value of the shares into which a bond is convertible is unaffected by ...

Investigation and improvement of high step- up converters for pv module applications

Directory of Open Access Journals (Sweden)

Hamed moradmand jazi

2017-01-01

Full Text Available sun is of the clean and cheapest sources of energy. Charging slight energy to electricity is carried out by PV modules. Since most electric consumers need Ac input voltage, the PV modules output voltage should be changed into Ac form. But, the voltage level of PV modules is much lower than the voltage needed in input stage of inverters. Because of large voltage level. Difference it is not possible to use the basic boost and buck-boost converters. The basic boost and buck-boost converters definitely can not be used in this applications, for, they will face extreme drop in efficiency in duty cycles closer to unity. In this paper The proposed converter is presented in order to decrease the voltage stress of coupled inductors based high step-up converters. The voltage stress in the proposed converter is lower than the high step-up boost converter with coupled inductors in identical condition. Also, soft switching condition for switches and diodes is realized by active clamp circuit, and with this technique and proper selection of duty cycle, large gain and high efficiency could be achieved ultimately. . In this paper theoretical analysis is used for analyzing the performance of the proposed converters, and in order to verify the theoretical analysis, simulated results from pspice software is provides.

Tumor necrosis factor alpha converting enzyme: an encouraging target for various inflammatory disorders.

Science.gov (United States)

Bahia, Malkeet S; Silakari, Om

2010-05-01

Tumor necrosis factor alpha is one of the most common pro-inflammatory cytokines responsible for various inflammatory disorders. It plays an important role in the origin and progression of rheumatoid arthritis and also in other autoimmune disease conditions. Some anti-tumor necrosis factor alpha antibodies like Enbrel, Humira and Remicade have been successfully used in these disease conditions as antagonists of tumor necrosis factor alpha. Inhibition of generation of active form of tumor necrosis factor alpha is a promising therapy for various inflammatory disorders. Therefore, the inhibition of an enzyme (tumor necrosis factor alpha converting enzyme), which is responsible for processing inactive form of tumor necrosis factor alpha into its active soluble form, is an encouraging target. Many tumor necrosis factor alpha converting enzyme inhibitors have been the candidates of clinical trials but none of them have reached in to the market because of their broad spectrum inhibitory activity for other matrix metalloproteases. Selectivity of tumor necrosis factor alpha converting enzyme inhibition over matrix metalloproteases is of utmost importance. If selectivity is achieved successfully, side-effects can be over-ruled and this approach may become a novel therapy for treatment of rheumatoid arthritis and other inflammatory disorders. This cytokine not only plays a pivotal role in inflammatory conditions but also in some cancerous conditions. Thus, successful targeting of tumor necrosis factor alpha converting enzyme may result in multifunctional therapy.

Preliminary Analysis of an Oscillating Surge Wave Energy Converter with Controlled Geometry: Preprint

Energy Technology Data Exchange (ETDEWEB)

Tom, Nathan; Lawson, Michael; Yu, Yi-Hsiang; Wright, Alan

2015-09-09

The aim of this paper is to present a novel wave energy converter device concept that is being developed at the National Renewable Energy Laboratory. The proposed concept combines an oscillating surge wave energy converter with active control surfaces. These active control surfaces allow for the device geometry to be altered, which leads to changes in the hydrodynamic properties. The device geometry will be controlled on a sea state time scale and combined with wave-to-wave power-take-off control to maximize power capture, increase capacity factor, and reduce design loads. The paper begins with a traditional linear frequency domain analysis of the device performance. Performance sensitivity to foil pitch angle, the number of activated foils, and foil cross section geometry is presented to illustrate the current design decisions; however, it is understood from previous studies that modeling of current oscillating wave energy converter designs requires the consideration of nonlinear hydrodynamics and viscous drag forces. In response, a nonlinear model is presented that highlights the shortcomings of the linear frequency domain analysis and increases the precision in predicted performance.

Semi-automatic logarithmic converter of logs

International Nuclear Information System (INIS)

Gol'dman, Z.A.; Bondar's, V.V.

1974-01-01

Semi-automatic logarithmic converter of logging charts. An original semi-automatic converter was developed for use in converting BK resistance logging charts and the time interval, ΔT, of acoustic logs from a linear to a logarithmic scale with a specific ratio for subsequent combining of them with neutron-gamma logging charts in operative interpretation of logging materials by a normalization method. The converter can be used to increase productivity by giving curves different from those obtained in manual, pointwise processing. The equipment operates reliably and is simple in use. (author)

Three-phase Resonant DC-link Converter

DEFF Research Database (Denmark)

Munk-Nielsen, Stig

The purpose of the project is to develop a three-phase resonant converter suitable for standard speed drives. The motivation for working with resonant converters is found in the problem of the standard converter type used today. In standard converter type Pulse Width Modulated-Voltage Source...... Inverter, PWM-VSI, the switches are subject to high current and voltage stress during switching, which causes losses. The fast switching of modern switches reduces switching losses. Unfortunately this procedure increased dv/dt and the size of the input/output filters of the PWM-SVI must be increased...

PV power system using hybrid converter for LED indictor applications

International Nuclear Information System (INIS)

Tseng, Sheng-Yu; Wang, Hung-Yuan; Chen, Chien-Chih

2013-01-01

Highlights: • This paper presents a LED indictor driving circuit with a PV arrays as its power source. • The perturb-and-observe method is adopted to extract the maximum power of PV arrays. • The proposed circuit structure has a less component counts and higher conversion efficiency. • A prototype of LED indictor driving circuit has been implemented to verify its feasibility. • The proposed hybrid converter is suitable for LED inductor applications. - Abstract: This paper presents a LED indictor driving circuit with a PV arrays as its power source. The LED indictor driving circuit includes battery charger and discharger (LED driving circuit). In this research, buck converter is used as a charger, and forward converter with active clamp circuit is adopted as a discharger to drive the LED indictor. Their circuit structures use switch integration technique to simplify them and to form the proposed hybrid converter, which has a less component counts, lighter weight, smaller size, and higher conversion efficiency. Moreover, the proposed hybrid converter uses a perturb-and-observe method to extract the maximum power from PV arrays. Finally, a prototype of an LED indictor driving circuit with output voltage of 10 V and output power of 20 W has been implemented to verify its feasibility. It is suitable for the LED inductor applications

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.

Passive Resonant Bidirectional Converter with Galvanic Barrier

Science.gov (United States)

Rosenblad, Nathan S. (Inventor)

2014-01-01

A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

Picosecond image-converter diagnostics

International Nuclear Information System (INIS)

Schelev, M.Ya.

1975-01-01

A brief review is presented of the improvements in picosecond image-converter diagnostics carried out since the previous Congress in 1972. The account is given under the following headings: picosecond image converter cameras for visible and x-ray radiation diagnostics; Nd:glass and ruby mode-locked laser measurements; x-ray plasma emission diagnostics; computer treatment of pictures produced by picosecond cameras. (U.K.)

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...

A Review on Direct Power Control for Applications to Grid Connected PWM Converters

Directory of Open Access Journals (Sweden)

T. A. Trivedi

2015-08-01

Full Text Available The Direct Power Control strategy has become popular as an alternative to the conventional vector oriented control strategy for grid connected PWM converters. In this paper, Direct Power Control as applied to various applications of grid connected converters is reviewed. The Direct Power Control for PWM rectifiers, Grid Connected DC/AC inverters applications such as renewable energy sources interface, Active Power Filters, Doubly Fed Induction Generators and AC-DC-AC converters are discussed. Control strategies such as Look-Up table based control, predictive control, Virtual Flux DPC, Model based DPC and DPC-Space Vector Modulation are critically reviewed. The effects of various key parameters such as selection of switching vector, sampling time, hysteresis band and grid interfacing on performance of direct power controlled converters are presented.

Autonomous Control of Interlinking Converter With Energy Storage in Hybrid AC–DC Microgrid

DEFF Research Database (Denmark)

Loh, Poh Chiang; Li, Ding; Chai, Yi Kang

2013-01-01

, simplicity, and industry relevance of the converter. The desired operating features of the hybrid microgrid can then be added through this interlinking converter. To demonstrate, an appropriate control scheme is now developed for controlling the interlinking converter. The objective is to keep the hybrid......The coexistence of ac and dc subgrids in a hybrid microgrid is likely given that modern distributed sources can either be ac or dc. Linking these subgrids is a power converter, whose topology should preferably be not too unconventional. This is to avoid unnecessary compromises to reliability...... microgrid in autonomous operation with active power proportionally shared among its distributed sources. Power sharing here should depend only on the source ratings and not their placements within the hybrid microgrid. The proposed scheme can also be extended to include energy storage within...

A Fast Time-to-Pulse Height Converter

Energy Technology Data Exchange (ETDEWEB)

Aspelund, O

1962-12-15

A fast time-to-pulse height converter representing a development of Green and Bell's gated beam converter is described. The converter is compatible with 2 input pulses in the stop channel and exhibits excellent linearity and time resolution properties. High stability and large output pulses are obtained by using a large time constant in the converting network.

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...

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.

Interferon beta induces apoptosis in nasopharyngeal carcinoma cells via the TRAIL-signaling pathway.

Science.gov (United States)

Makowska, Anna; Wahab, Lora; Braunschweig, Till; Kapetanakis, Nikiforos-Ioannis; Vokuhl, Christian; Denecke, Bernd; Shen, Lian; Busson, Pierre; Kontny, Udo

2018-03-06

The combination of neoadjuvant chemotherapy, radiochemotherapy, and maintenance therapy with interferon beta (IFNβ) has led to superior results in the treatment of children and adolescents with nasopharyngeal carcinoma (NPC). However, nothing is known about the mechanism of the antitumor activity of IFNβ in NPC. Here, we investigate the role of IFNβ on apoptosis in NPC cells. Six NPC cell lines, one patient-derived NPC xenograft (PDX) and one SV40-transformed nasoepithelial cell line were used. Induction of apoptosis by IFNβ was measured by flow cytometric analysis of subG1-DNA-content, Hoechst 33258 staining and activation of caspase-3. Dissection of death ligand signaling pathways included measuring surface expression of its components by flow cytometry, activation by death ligands and neutralization with specific antibodies and siRNA. IFNβ induced apoptosis at concentrations achievable in humans in five of six NPC cell lines and in PDX cells but not in nasoepithelial cells. Inhibition of caspases-3 and -8 abrogated this effect suggesting IFNβ promoted apoptosis through the extrinsic pathway. IFNβ induced surface expression of TRAIL and TRAIL-R2 and the addition of an anti-TRAIL-antibody or transfection with TRAIL-siRNA blocked IFNβ-induced apoptosis. No induction of TRAIL-expression was noted in the IFNβ-resistant cell line. In conclusion, IFNβ leads to apoptosis in NPC cells in an autocrine way via the induction of TRAIL expression and subsequent activation of the TRAIL-signaling pathway. The mechanism described could at least partly explain the clinical benefit of IFNβ in the treatment of NPC. Further studies in a mouse-xenograft model are warranted to substantiate this effect in vivo .

Studies of ZVS soft switching of dual-active-bridge isolated bidirectional DC-DC converters

Science.gov (United States)

Xu, Fei; Zhao, Feng; Shi, Qibiao; Wen, Xuhui

2018-05-01

To operate dual-active-bridge isolated bidirectional dc- dc converter (DAB) at high efficiency, the two bridge switches must operate with Zero-Voltage-Switching (ZVS) over as wide an operating range as possible. This paper proposes a new perspective on realizing ZVS in dead-time. An exact theoretical analysis and mathematical mode is built to explain the process of ZVS switching in dead-time under Single Phase Shift (SPS) control strategy. In order to assure the two bridge switches operate on soft switching, every SPS switching point is analyzed. Generally, dead-time will be determined when the power electronic devices is selected. The key factor to realizing ZVS is the size of the end time of resonance comparing to dead-time. Through detailed analysis, it can obtain the conditions of all switches achieving ZVS turn-on and turn-off. Finally, simulation validates the theoretical analysis and some advice are given to realize the ZVS soft switching.

Correlation of endothelin-1 concentration and angiotensin-converting enzyme activity with the staging of liver fibrosis.

Science.gov (United States)

Kardum, Dusko; Fabijanić, Damir; Lukić, Anita; Romić, Zeljko; Petrovecki, Mladen; Bogdanović, Zoran; Jurić, Klara; Urek-Crncević, Marija; Banić, Marko

2012-06-01

Increased serum angiotensin-converting enzyme (SACE) activity and serum concentration of endothelin-1 (ET-1) were found in liver cirrhosis. We investigated a correlation between the different stages of liver fibrosis and SACE activity and serum ET-1 concentration. Seventy patients with pathohistologically established chronic liver disease were divided in three groups according to Ishak criteria for liver fibrosis: minimal fibrosis (Ishak score 0-1, n =20), medium fibrosis (Ishak score 2-5, n=20) and cirrhosis (Ishak score 6, n=30). SACE activity and ET-1 concentration were determined using commercial ELISA kits. SACE activity and ET-1 concentrations were proportional to the severity of disease, the highest being in patients with liver cirrhosis. Maximal increase in SACE activity was found between minimal and medium fibrosis while maximal increase in ET-1 concentration was revealed between medium fibrosis and cirrhosis. The analysis of the Receiver Operating Characteristic (ROC) curve for SACE activity suggested a cut-off value to separate minimal from medium fibrosis at 59.00 U/L (sensitivity 100%, specificity 64.7%). The cut-off value for serum ET-1 concentration to separate medium fibrosis from cirrhosis was 12.4 pg/mL (sensitivity 96.8%, specificity 94.4%). A positive correlation between SACE activity and ET-1 concentration was registered (Spearman's ñ = 0.438, p = 0.004). Both SACE activity and ET-1 concentration were increased in all stages of liver fibrosis. Cut-off points for SACE activity and ET-1 concentration could be a biochemical marker for the progression of fibrosis. Positive correlation between SACE activity and ET-1 concentration might indicate their interaction in the development of liver cirrhosis.

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.

A novel grounded to floating admittance converter with electronic control

Science.gov (United States)

Prasad, Dinesh; Ahmad, Javed; Srivastava, Mayank

2018-01-01

This article suggests a new grounded to floating admittance convertor employing only two voltage differencing transconductance amplifiers (VDTAs). The proposed circuit can convert any arbitrary grounded admittance into floating admittance with electronically controllable scaling factor. The presented converter enjoys the following beneficial: (1) no requirement of any additional passive element (2) scaling factor can be tuned electronically through bias currents of VDTAs (3) no matching constraint required (4) low values of active/passive sensitivity indexes and (5) excellent non ideal behavior that indicates no deviation in circuit behavior even under non ideal environment. Application of the proposed configuration in realization of floating resistor and floating capacitor has been presented and the workability of these floating elements has been confirmed by active filter design examples. SPICE simulations have been performed to demonstrate the performance of the proposed circuits.

Design-Oriented Analysis of Resonance Damping and Harmonic Compensation for LCL-Filtered Voltage Source Converters

DEFF Research Database (Denmark)

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

2014-01-01

This paper addresses the interaction between harmonic resonant controllers and active damping of LCL resonance in voltage source converters. A virtual series R-C damper in parallel with the filter capacitor is proposed with the capacitor current feedback loop. The phase lag resulting from...... crossover frequency defined by the proportional gain of current controller. This is of particular interest for high-performance active harmonic filtering applications and low-pulse-ratio converters. Case studies in experiments validate the theoretical analysis....

Transformerless dc-Isolated Converter

Science.gov (United States)

Rippel, Wally E.

1987-01-01

Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.

Thermionic photovoltaic energy converter

Science.gov (United States)

Chubb, D. L. (Inventor)

1985-01-01

A thermionic photovoltaic energy conversion device comprises a thermionic diode mounted within a hollow tubular photovoltaic converter. The thermionic diode maintains a cesium discharge for producing excited atoms that emit line radiation in the wavelength region of 850 nm to 890 nm. The photovoltaic converter is a silicon or gallium arsenide photovoltaic cell having bandgap energies in this same wavelength region for optimum cell efficiency.

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...

Angiotensin converting enzyme 1 in the median preoptic nucleus contributes to chronic intermittent hypoxia hypertension.

Science.gov (United States)

Faulk, Katelynn E; Nedungadi, T Prashant; Cunningham, J Thomas

2017-05-01

Obstructive sleep apnea is associated with hypertension and cardiovascular disease. Chronic intermittent hypoxia is used to model the arterial hypoxemia seen in sleep apnea patients and is associated with increased sympathetic nerve activity and a sustained diurnal increase in blood pressure. The renin angiotensin system has been associated with hypertension seen in chronic intermittent hypoxia. Angiotensin converting enzyme 1, which cleaves angiotensin I to the active counterpart angiotensin II, is present within the central nervous system and has been shown to be regulated by AP-1 transcription factors, such as ΔFosB. Our previous study suggested that this transcriptional regulation in the median preoptic nucleus contributes to the sustained blood pressure seen following chronic intermittent hypoxia. Viral mediated delivery of a short hairpin RNA against angiotensin converting enzyme 1 in the median preoptic nucleus was used along with radio-telemetry measurements of blood pressure to test this hypothesis. FosB immunohistochemistry was utilized in order to assess the effects of angiotensin converting enzyme 1 knockdown on the activity of nuclei downstream from median preoptic nucleus. Angiotensin converting enzyme 1 knockdown within median preoptic nucleus significantly attenuated the sustained hypertension seen in chronic intermittent hypoxia. Angiotensin converting enzyme 1 seems to be partly responsible for regulating downstream regions involved in sympathetic and blood pressure control, such as the paraventricular nucleus and the rostral ventrolateral medulla. The data suggest that angiotensin converting enzyme 1 within median preoptic nucleus plays a critical role in the sustained hypertension seen in chronic intermittent hypoxia. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Clustering of cycloidal wave energy converters

Science.gov (United States)

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.

Valuing Convertible Bonds Based on LSRQM Method

Directory of Open Access Journals (Sweden)

Jian Liu

2014-01-01

Full Text Available Convertible bonds are one of the essential financial products for corporate finance, while the pricing theory is the key problem to the theoretical research of convertible bonds. This paper demonstrates how to price convertible bonds with call and put provisions using Least-Squares Randomized Quasi-Monte Carlo (LSRQM method. We consider the financial market with stochastic interest rates and credit risk and present a detailed description on calculating steps of convertible bonds value. The empirical results show that the model fits well the market prices of convertible bonds in China’s market and the LSRQM method is effective.

Proposed electromagnetic wave energy converter

Science.gov (United States)

Bailey, R. L.

1973-01-01

Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

PENGARUH DEGRADASI ENZIM PROTEOLITIK TERHADAP AKTIVITAS ANGIOTENSIN CONVERTING ENZYME INHIBITOR BEKASAM DENGAN Lactobacillus plantarum B1765 (The Effect of Degradation of Proteolitic Enzyme on Angiotensin Converting Enzyme Inhibitor Activity of Bekasam with Lactobacillus plantarum B1765

Directory of Open Access Journals (Sweden)

Prima Retno Wikandari

2016-10-01

Full Text Available This research studied the effect of digestive enzyme degradation on the Angiotensin Converting Enzyme Inhibitor (ACEI activity and the stability of bekasam peptide and ACEI activity. Water extract of bekasam was subjected to pepsin and trypsin. The stability of peptide was measured from the changes of peptide concentration before and after treatment by those enzymes. The stability of ACEI activity was measured by hypuric acid liberated from Hip-His-Leu as ACE substrate and determined by spectrophotometer. The results showed that proteolytic enzyme degradation did not affect the concentration of peptide (p>0,05 and the mean concentration 36.72. It was closely related with the ACEI activity that did not change significantly before and after digestion by pepsin and trypsin (p>0,05 and the mean ACEI activity was 70.73. It showed that ACEI activity of bekasam did not change by the degradation of digestive enzyme. Keywords: bekasam, fermented fish, peptides, ACEI activity ABSTRAK Penelitian ini bertujuan untuk mengkaji pengaruh degradasi enzim pencernaan proteolitik terhadap stabilitas peptida dan aktivitas Angiotensin Converting Enzyme Inhibitor (ACEI bekasam yang difermentasi dengan kultur starter Lactobacillus plantarum B1765. Terhadap ekstrak bekasam diberi perlakuan enzim proteolitik pepsin dan tripsin. Pengujian stabilitas peptida diukur dengan ada tidaknya perubahan jumlah peptida setelah perlakuan enzim menggunakan metode formol, sedangkan aktivitas ACEI dilakukan dengan mengetahui jumlah asam hipurat dari substrat Hip-His-Leu yang dibebaskan oleh ACE diukur dengan spektrofotometer. Hasil pengujian menunjukkan perlakuan enzim proteolitik tidak berpengaruh pada konsentrasi peptida dengan p>0,05 dengan nilai rata-rata konsentrasi peptida sebesar 36,72. Hal ini berkorelasi dengan aktivitas ACEI yang juga menunjukkan tidak ada pengaruh antara perlakuan sebelum dan setelah degradasi enzim (p>0,05 dengan rata-rata aktivitas ACEI sebesar 70,73. Hasil

SYNTHESIS OF AUTOMATIC CONTROL SYSTEM FOR STEPPING-UP CONVERTER OF DC VOLTAGE AT ACTIVE LOAD OPERATION

Directory of Open Access Journals (Sweden)

A. V. Мironovich

2005-01-01

Full Text Available Investigation of a nontransformer stepping-up converter of dc voltage has been carried out. A non-linear structural circuit of the converter has been developed with the help of the controlled current injection method. A linearization of an object and an automation control system synthesis have been conducted applying method of successive optimization of the circuits. The paper contains results of transient process simulation in the linear computer model and in the power electronics computer model. 

Soft switching buck-boost converter for photovoltaic power generation; Taiyoko hatsuden no tame no soft switching shokoatsu converter

Energy Technology Data Exchange (ETDEWEB)

Lee, H. [Kyungnam University (Korea, Republic of)

1996-10-27

A soft switching method with small switching loss was proposed for the purpose of increasing the efficiency of a DC-DC boost converter which converted a DC current generated by solar cells to a variable DC current. Existing current converters are supplemented by using a snubber circuit around the switch so as to protect the switch by a hard switching action. However, with an increase of the output current, snubber loss is increased, reducing the efficiency. In order to solve this problem, the partial resonant switch method was applied to the converter; with this method of partially forming a resonant circuit only at the time of turning on/off of the switch, the switching loss was reduced through the soft switching, thereby making the proposed converter operate with high efficiency. Moreover, the resonant element of the partial resonant circuit using a snubber condenser, the energy accumulated in the condenser was regenerated on the power supply side without loss of snubber. With the regenerated energy, the proposed converter was provided with a smaller ratio of switching to use than the conventional converter. 4 refs., 7 figs., 1 tab.

Picropodophyllin inhibits tumor growth of human nasopharyngeal carcinoma in a mouse model

International Nuclear Information System (INIS)

Yin, Shu-Cheng; Guo, Wei; Tao, Ze-Zhang

2013-01-01

Highlights: •We identified that PPP inhibits IGF-1R/Akt pathway in NPC cells. •PPP dose-dependently inhibits NPC cell proliferation in vitro. •PPP suppresses tumor growth of NPC in nude mice. •PPP have little effect on microtubule assembly. -- Abstract: Insulin-like growth factor-1 receptor (IGF-1R) is a cell membrane receptor with tyrosine kinase activity and plays important roles in cell transformation, tumor growth, tumor invasion, and metastasis. Picropodophyllin (PPP) is a selective IGF-1R inhibitor and shows promising antitumor effects for several human cancers. However, its antitumor effects in nasopharyngeal carcinoma (NPC) remain unclear. The purpose of this study is to investigate the antitumor activity of PPP in NPC using in vitro cell culture and in vivo animal model. We found that PPP dose-dependently decreased the IGF-induced phosphorylation and activity of IGF-1R and consequently reduced the phosphorylation of Akt, one downstream target of IGF-1R. In addition, PPP inhibited NPC cell proliferation in vitro. The half maximal inhibitory concentration (IC50) of PPP for NPC cell line CNE-2 was ⩽1 μM at 24 h after treatment and ⩽0.5 μM at 48 h after treatment, respectively. Moreover, administration of PPP by intraperitoneal injection significantly suppressed the tumor growth of xenografted NPC in nude mice. Taken together, these results suggest targeting IGF-1R by PPP may represent a new strategy for treatment of NPCs with positive IGF-1R expression

Picropodophyllin inhibits tumor growth of human nasopharyngeal carcinoma in a mouse model

Energy Technology Data Exchange (ETDEWEB)

Yin, Shu-Cheng [Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan 430060 (China); Department of Otolaryngology – Head and Neck Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071 (China); Guo, Wei [Department of Otolaryngology – Head and Neck Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071 (China); Tao, Ze-Zhang, E-mail: zezhangtao@gmail.com [Department of Otolaryngology – Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan 430060 (China)

2013-09-13

Highlights: •We identified that PPP inhibits IGF-1R/Akt pathway in NPC cells. •PPP dose-dependently inhibits NPC cell proliferation in vitro. •PPP suppresses tumor growth of NPC in nude mice. •PPP have little effect on microtubule assembly. -- Abstract: Insulin-like growth factor-1 receptor (IGF-1R) is a cell membrane receptor with tyrosine kinase activity and plays important roles in cell transformation, tumor growth, tumor invasion, and metastasis. Picropodophyllin (PPP) is a selective IGF-1R inhibitor and shows promising antitumor effects for several human cancers. However, its antitumor effects in nasopharyngeal carcinoma (NPC) remain unclear. The purpose of this study is to investigate the antitumor activity of PPP in NPC using in vitro cell culture and in vivo animal model. We found that PPP dose-dependently decreased the IGF-induced phosphorylation and activity of IGF-1R and consequently reduced the phosphorylation of Akt, one downstream target of IGF-1R. In addition, PPP inhibited NPC cell proliferation in vitro. The half maximal inhibitory concentration (IC50) of PPP for NPC cell line CNE-2 was ⩽1 μM at 24 h after treatment and ⩽0.5 μM at 48 h after treatment, respectively. Moreover, administration of PPP by intraperitoneal injection significantly suppressed the tumor growth of xenografted NPC in nude mice. Taken together, these results suggest targeting IGF-1R by PPP may represent a new strategy for treatment of NPCs with positive IGF-1R expression.

Fault isolation in parallel coupled wind turbine converters

DEFF Research Database (Denmark)

Odgaard, Peter Fogh; Thøgersen, Paul Bach; Stoustrup, Jakob

2010-01-01

Parallel converters in wind turbine give a number advantages, such as fault tolerance due to the redundant converters. However, it might be difficult to isolate gain faults in one of the converters if only a combined power measurement is available. In this paper a scheme using orthogonal power...... references to the converters is proposed. Simulations on a wind turbine with 5 parallel converters show a clear potential of this scheme for isolation of this gain fault to the correct converter in which the fault occurs....

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.

Novel screening techniques for wind turbine power converters

DEFF Research Database (Denmark)

Jørgensen, Asger Bjørn; Sønderskov, Simon Dyhr; Christensen, Nicklas

2016-01-01

Power converters represent one of the highest failure rates in the wind turbine. Therefore converter manufacturers perform burn-in tests to prevent shipping of faulty converters. Recent developments in junction temperature estimation, based on accurate online IGBT collector-emitter voltage...... measurements, allow for thermal stress estimation of the IGBT modules. This is utilized to detect infant mortalities in power converters, by comparing thermal responses of IGBTs for faulty and non-faulty converters. The method proves to be a time and cost efficient candidate to replace burn-in tests of power...... converters for wind turbines applications....

Family of Step-up DC/DC Converters with Fast Dynamic Response for Low Power Applications

DEFF Research Database (Denmark)

N. Soltani, Mohsen; Mostaan, Ali; Siwakoti, Yam Prasad

2016-01-01

This study presents a family of novel step-up DC/DC converters which do not have a right half plane zero in their transfer function resulting in faster dynamic behaviour of the converters under the load variation. In addition, the voltage stress on all the active switches and diodes is as low...

Neutron sources for neutrino investigations with the lithium converter

International Nuclear Information System (INIS)

Lyashuk, V.I.; Lutostansky, Yu.S.

2012-01-01

Creation of the powerful antineutrino source with a hard spectrum is possible on the base of β - -decay of the short lived 8 Li (T 1/2 = 0.84 s) isotope formed in the reaction 7 Li(n,γ) 8 Li. The 8 Li. isotope is a prime perspective antineutrino source taking into account that neutrino cross section depends as σ ∼ E ν 2 at the considered energy. The creation of this type powerful neutrino source (neutrino factory) is possible by (n,γ)-activation of high-purified 7 Li isotope under intensive neutron flux. As a neutron source for this purpose can be used the nuclear reactors (of steady-state flux and pulsed one), neutron sources on the base of accelerators and neutron generating targets, beam-dumps of large accelerators. The capabilities and perspectives of neutron sources are considered for the purpose of creation of the neutrino factory. Different realizations of lithium antineutrino sources (lithium converter on the base of high purified 7 Li isotope) are discussed: static regime (i.e., without transport of 8 Li isotope to the detector); dynamic regime (pumping of activated lithium to a remote detector in a closed cycle); lithium converter on the base of (a) a pulse reactors and (b) constructed as tandem of an antineutrino source and accelerator with a neutron-producing target. Heavy water solution of LiOD is proposed as a substance for the lithium converter. The expressions for neutrino fluxes in the detector position are obtained

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

Power electronic converters enable wind turbines, operating at variable speed, to generate electricity more efficiently. Among variable speed operating turbine generators, permanent magnetic synchronous generator (PMSG) has got more attentions due to low cost and maintenance requirements...... 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...

Ac-dc converter firing error detection

International Nuclear Information System (INIS)

Gould, O.L.

1996-01-01

Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal

3-Bromopyruvate enhances TRAIL-induced apoptosis in human nasopharyngeal carcinoma cells through CHOP-dependent upregulation of TRAIL-R2.

Science.gov (United States)

Can, Zhou; Lele, Song; Zhirui, Zhang; Qiong, Pan; Yuzhong, Chen; Lingling, Liu; Surong, Zhao; Yiming, Sun; Pei, Zhang; Chenchen, Jiang; Liu, Hao

2017-08-01

Past reports have shown that the sensitivity of cancer cells to TRAIL-induced apoptosis is related to their expression of TRAIL-death receptors on the cell surface. However, the level of TRAIL-death receptors expression on cancer cells is always low. Our previous research showed that nasopharyngeal carcinoma (NPC) cells have a poor sensitivity to low doses of TRAIL. Here, we evaluated combined treatment with the energy inhibitor 3-bromopyruvate (3BP) and TRAIL as a method to produce an increased apoptotic response in NPC cells. The results showed that 3BP and TRAIL together produced higher cytotoxicity and increased TRAIL-R2 expression in NPC cells compared with the effects of either 3BP or TRAIL alone. These findings led us to hypothesize that 3BP may sensitize NPC cells to TRAIL. 3BP is a metabolic blocker that inhibits hexokinase II activity, suppresses ATP production, and induces endoplasmic reticulum (ER) stress. Our results showed that 3BP also activated AMP-activated protein kinase, which we found to play an important role in the induction of ER stress by 3BP. Furthermore, the induction of TRAIL-R2 expression and the sensitization of the NPC cells to TRAIL by 3BP were reduced when we inhibited the expression of CHOP. Taken together, our results showed that a low dose of 3BP sensitized NPC cells to TRAIL-induced apoptosis by the upregulation of CHOP, which was mediated by the activation of AMP-activated protein kinase and ER stress. The results showed that 3BP is a promising candidate agent for enhancing the therapeutic response to TRAIL in NPC.

Do Convertible Bond Issuers Cater to Investor Demand?

NARCIS (Netherlands)

de Jong, Abe; Duca, Eric; Dutordoir, Marie

2013-01-01

We examine the impact of fluctuations in investor demand for convertible securities on convertible bond issue volumes, pricing, and design. We find evidence of a positive impact of investor demand proxies on convertible bond issue volumes. We also document significantly lower convertible bond

Converter Monitoring Unit for Retrofit of Wind Power Converters

DEFF Research Database (Denmark)

Rannestad, Bjorn; Maarbjerg, Anders Eggert; Frederiksen, Kristian

2018-01-01

A Converter Monitoring Unit (CMU), which will enable condition monitoring of wind turbine converters is presented in this paper. Reducing the cost of corrective maintenance by means of condition monitoring is a way of lowering Operation & Maintenance (O&M) costs for wind turbine systems....... The CMU must be able to detect a broad range of failure modes related to Insulated Gate Bipolar Transistor (IGBT) power modules and associated gate drives. IGBT collector-emitter on-state voltage (vceon) and current (ic) is sampled in the CMU and used for detection of emerging failures. A new method...... for compensation of unwanted inductive voltage drop in the vceon measurement path is presented, enabling retrofitting of CMUs in existing wind turbines. Finally, experimental results obtained on a prototype CMU are presented. Experimentally the vceon dependency to IGBT junction temperature and deterioration...

The APA Style Converter: a Web-based interface for converting articles to APA style for publication.

Science.gov (United States)

Li, Ping; Cunningham, Krystal

2005-05-01

The APA Style Converter is a Web-based tool with which authors may prepare their articles in APA style according to the APA Publication Manual (5th ed.). The Converter provides a user-friendly interface that allows authors to copy and paste text and upload figures through the Web, and it automatically converts all texts, references, and figures to a structured article in APA style. The output is saved in PDF or RTF format, ready for either electronic submission or hardcopy printing.

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...

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 con...

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...... 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....

Circular waveguide mode converters at 140 GHz

International Nuclear Information System (INIS)

Trulsen, J.; Woskoboinikow, P.; Temkin, R.J.

1986-01-01

A unified derivation of the coupled mode equations for circular waveguide is presented. Also, approximate design criteria for TE/sub 0n/ to TE/sub 0n'/ axisymmetric, TE 01 to TE 11 wriggle, and TE 01 to TM 11 bend converters are reviewed. Numerically solving the coupled mode equations, an optimized set of mode converters has been designed for conversion of a 2 millimeter wave TE 03 mode into TE 11 . This set consists of axisymmetric TE 03 to TE 02 and TE 02 to TE 01 converters followed by a wriggle TE 01 to TE 11 converter. This mode converter set was fabricated and tested using a 3 kW, 137 GHz gyrotron. A TE 11 mode purity of better than 97% was achieved. The TE 01 to TE 11 wriggle converter was experimentally optimized for a measured conversion efficiency of better than 99% not including ohmic losses

A zero-voltage-switched three-phase interleaved buck converter

Science.gov (United States)

Hsieh, Yao-Ching; Huang, Bing-Siang; Lin, Jing-Yuan; Pham, Phu Hieu; Chen, Po-Hao; Chiu, Huang-Jen

2018-04-01

This paper proposes a three-phase interleaved buck converter which is composed of three identical paralleled buck converters. The proposed solution has three shunt inductors connected between each other of three basic buck conversion units. With the help of the shunt inductors, the MOSFET parasitic capacitances will resonate to achieve zero-voltage-switching. Furthermore, the decreasing rate of the current through the free-wheeling diodes is limited, and therefore, their reverse-recovery losses can be minimised. The active power switches are controlled by interleaved pulse-width modulation signals to reduce the input and output current ripples. Therefore, the filtering capacitances on the input and output sides can be reduced. The power efficiency is measured to be as high as 98% in experiment with a prototype circuit.

Salvaging of nuclear waste by nuclear-optical converters

Science.gov (United States)

Karelin, A. V.; Shirokov, R. V.

2007-06-01

In modern conditions of power consumption growing in Russia, apparently, it is difficult to find alternative to further development of nuclear power engineering. The negative party of nuclear power engineering is the spent fuel of nuclear reactors (radioactive waste). The gaseous and fluid radioactive waste furbished of highly active impurity, dumps in atmosphere or pools. The highly active fluid radioactive waste stores by the way of saline concentrates in special tanks in surface layers of ground, above the level of groundwaters. A firm radioactive waste bury in pods from a stainless steel in underground workings, salt deposits, at the bottom of oceans. However this problem can be esteemed in a positive direction, as irradiation is a hard radiation, which one can be used as a power source in nuclear - optical converters with further conversion of optical radiation into the electric power with the help of photoelectric converters. Thus waste at all do not demand special processing and exposure in temporary storehouses. And the electricity can be worked out in a constant mode within many years practically without gang of a stimulus source, if a level of a residual radioactivity and the half-lives of component are high enough.

Chinese medicinal formula Fufang Xueshuantong capsule could inhibit the activity of angiotensin converting enzyme

Science.gov (United States)

Sheng, Shujing; Wang, Yonggang; Long, Chaofeng; Su, Weiwei; Rong, Xia

2014-01-01

Fufang Xueshuantong (FXST) capsule, a Chinese medicinal formula composed of four herbals – Panax notoginseng, Radix Astragali, Radix Salvia Miltiorrhizae and Radix Scrophulariaceae, has been used to treat cardiovascular diseases for many years, but the pharmacological mechanisms underlying its effects has not been clarified. This study investigates if a connection between FXST and angiotensin converting enzyme (ACE) might be an explanation for its pharmacological effects. ACE inhibition assay was performed on FXST capsule, 50% ethanol extracts from the four herbals and three selected saponins most abundant in P. notoginseng (Ginsenoside Rg1, Ginsenoside Rb1 and Notoginsenoside R1) using a biochemical test. Reversed-phase high-performance liquid chromatography of liberated hippuric acid from the ACE assay was conducted to determine the inhibitory effect. As a result, FXST and extracts from P. notoginseng showed a significant and dose-dependent inhibition on ACE activity with the IC50 values of 115 μg/ml and 179 μg/ml, respectively. But extracts from the other three herbals and the three selected saponins had no significant effect on ACE inhibition. Compared to other reported plant extracts, FXST could be considered as an effective ACE inhibitor. The inhibition of ACE activity supports the traditional use of FXST on blood circulation and the inhibitory property of FXST is mainly caused by P. notoginseng. PMID:26019516

Are there endogenous stem cells in the spinal cord?

Science.gov (United States)

Ferrucci, Michela; Ryskalin, Larisa; Busceti, Carla L; Gaglione, Anderson; Biagioni, Francesca; Fornai, Francesco

2017-12-01

Neural progenitor cells (NPC) represent the stem-like niche of the central nervous system that maintains a regenerative potential also in the adult life. Despite NPC in the brain are well documented, the presence of NPC in the spinal cord has been controversial for a long time. This is due to a scarce activity of NPC within spinal cord, which also makes difficult their identification. The present review recapitulates the main experimental studies, which provided evidence for the occurrence of NPC within spinal cord, with a special emphasis on spinal cord injury and amyotrophic lateral sclerosis. By using experimental models, here we analyse the site-specificity, the phenotype and the main triggers of spinal cord NPC. Moreover, data are reported on the effect of specific neurogenic stimuli on these spinal cord NPC in an effort to comprehend the endogenous neurogenic potential of this stem cell niche.

Design, operation and control of series-connected power converters for offshore wind parks

Energy Technology Data Exchange (ETDEWEB)

Ruiz, Alejandro Garces

2012-07-01

Offshore wind farms need to develop technologies that fulfill three main objectives:Efficiency, power density and reliability. The purpose of this thesis is to study an HVDC transmission system based on series connection of the turbines which theoretically meet these three objectives. A new topology of matrix converter operated at high frequency is proposed. This converter is studied using different modulation algorithms. Simulation and experimental results demonstrated that the converter can be operated as a current source converter with high efficiency. An optimal control based on a linear quadratic regulator is propose dto control the matrix converter as well as the converter placed on shore. Results demonstrated the high performance of this type of control and its simplicity for implementation. An stationary state study based on non-linear programming and Montecarlo simulation was carried out to determine the performance of the concept for long-term operation. Series connection is an efficient technology if and only if the differences in the effective wind velocity are small. This aspect limits the number of wind turbines that can be connected in series, since a numerous number of turbines will lead to high covariances in the distribution of the wind. A complementary study about active filter and reactive power compensation was carried out using an optimization-based algorithm. (Author)

DESIGN OPTIMIZATION OF RESONANT DC-DC CONVERTERS

OpenAIRE

Belqasem Aljafari

2016-01-01

Resonant DC/DC converters are the class of converters, which have L-C resonant tank serving as a major part of the power conversion process. The fundamental concept of the resonant converter is that the circulating energy in an L-C resonant circuit is manageable by changing the operating frequency, and therefore the converter can condition the input power to the desired output voltage. The development in power conversion technology is steady demand for high power efficiency and high power den...

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.

Improvements in x-ray image converters and phosphors

International Nuclear Information System (INIS)

Rabatin, J.G.

1981-01-01

Improvements to an X-ray image converter comprising crystals of rare earth phosphor admixtures are described. The phosphor admixtures utilize thulium-activated lanthanum and/or gadolinium oxyhalide phosphor material to increase the relative speed and resolution of an X-ray image compared with conventional rare earth phosphors. Examples of various radiographic screens containing one or more of the phosphor materials are given. (U.K.)

Andrographolide Suppresses Proliferation of Nasopharyngeal Carcinoma Cells via Attenuating NF-κB Pathway

Directory of Open Access Journals (Sweden)

Tao Peng

2015-01-01

Full Text Available Andrographolide (Andro has been reported to have anticancer activity in multiple types of cancer due to its capacity to inactivate NF-κB pathway. Previous studies showed the therapeutic potential of targeting NF-κB pathway in nasopharyngeal carcinoma (NPC. However, the anticancer activity of Andro in NPC has not been reported. In this study, we defined the anticancer effects of Andro in NPC and elucidated its potential mechanisms of action. Our results showed that Andro significantly inhibited the proliferation and invasion of NPC cells (P<0.05, resp.. These anticancer activities were associated with cell apoptosis, cell death and induction of cell cycle arrest, and the downregulation of NF-κB target genes. This work provides evidence that NF-κB pathway is a potential therapeutic target and may also be indispensable in the Andro-mediated anticancer activities in nasopharyngeal carcinoma.

Control scheme of three-level H-bridge converter for interfacing between renewable energy resources and AC grid

DEFF Research Database (Denmark)

Pouresmaeil, Edris; Montesinos-Miracle, Daniel; Gomis-Bellmunt, Oriol

2011-01-01

This paper presents a control strategy of multilevel converters for integration of renewable energy resources into power grid. The proposed technique provides compensation for active, reactive, and harmonic current components of grid-connected loads. A three-level H-bridge converter is proposed a...

Radiation inactivation of angiotensin-converting enzyme in solutions. Communication 3. The effect of NaCl

International Nuclear Information System (INIS)

Orlova, M.A.; Kost, O.A.; Nikol'skaya, I.I.; Troshina, N.N.; Binevskij, P.V.

1999-01-01

The effect of 0-0.15 M NaCl on the dose response of angiotensin-converting enzyme is described. The data represented at three-dimensional surfaces demonstrate the existence of special areas where definite mechanisms of dose response are predominant. In acidic and alkaline media, the regions of high values of enzyme activation can be emphasized; moreover, the oscillations of enzyme activity can also be detected. At pH 7.5, when angiotensin-converting enzyme conformation is less rigid, activation peaks on the three-dimensional surface are less pronounced indicating the decreasing effect of NaCl on dose response at this pH value [ru

Hypocholesterolemic properties of grapefruit (Citrus paradisii and shaddock (Citrus maxima juices and inhibition of angiotensin-1-converting enzyme activity

Directory of Open Access Journals (Sweden)

Ganiyu Oboh

2014-12-01

Full Text Available Grapefruit (Citrus paradisii and shaddock (Citrus maxima juices are used in folk medicine for the management of hypertension and other cardiovascular diseases, but the mechanism of action by which they exert their therapeutic action is unclear. The aim of this study was to investigate the effect of grapefruit and shaddock juices on angiotensin-1-converting enzyme (ACE activity in vitro and the hypocholesterolemic properties of the juices in rats fed a high-cholesterol diet. Grapefruit juice had higher total phenol and flavonoid contents than shaddock juice, while both juices inhibited ACE activity in a dose-dependent manner. Furthermore, administration of the juices to rats fed a high-cholesterol diet caused a significant reduction in plasma total cholesterol, triglyceride, and low-density lipoprotein–cholesterol levels and an increase in high-density lipoprotein–cholesterol levels. The inhibition of ACE activity in vitro and in vivo hypocholesterolemic effect of the juices could explain the use of the juices in the management of cardiovascular diseases.

Wavelength-independent all-fiber mode converters.

Science.gov (United States)

Lai, K; Leon-Saval, S G; Witkowska, A; Wadsworth, W J; Birks, T A

2007-02-15

We have used two different photonic crystal fiber (PCF) techniques to make all-fiber mode converters. An LP(01) to LP(11) mode converter was made by the ferrule technique on a drawing tower, and an LP(01) to LP(02) mode converter was made by controlled hole inflation of an existing PCF on a tapering rig. Both devices rely on adiabatic propagation rather than resonant coupling; so high extinction was achieved across a wide wavelength range.

Fast parallel-series analog-to-digital converter

International Nuclear Information System (INIS)

Pogosov, A.Yu.

1987-01-01

Fast analog-to-digital converters are used in systems for detection of rapid processes, nuclear spectroscopy. A 12-digit analog-to-digital converter with conversion time of 160 ns and conversion frequency of 8.3 MHz is described; a segmented digital-to-analog converter with differential non-linearity of < 0.01% and a differential amplifier-limiter with setting time of 80 ns at the error of 0.2% are utilized in the converter; a control device is based on the chain of flip-flop circuit

A review of Indirect Matrix Converter Topologies

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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.

Quantitative comparison of the efficacy of various compounds in lowering intracellular cholesterol levels in Niemann-Pick type C fibroblasts.

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Zachary T Wehrmann

Full Text Available Niemann-Pick Type C disease (NPC is a lethal, autosomal recessive disorder caused by mutations in the NPC1 and NPC2 cholesterol transport proteins. NPC's hallmark symptoms include an accumulation of unesterified cholesterol and other lipids in the late endosomal and lysosomal cellular compartments, causing progressive neurodegeneration and death. Although the age of onset may vary in those affected, NPC most often manifests in juveniles, and is usually fatal before adolescence. In this study, we investigated the effects of various drugs, many of which modify the epigenetic control of NPC1/NPC2 gene expression, in lowering the otherwise harmful elevated intracellular cholesterol levels in NPC cells. Our studies utilized a previously described image analysis technique, which allowed us to make quantitative comparisons of the efficacy of these drugs in lowering cholesterol levels in a common NPC1 mutant model. Of the drugs analyzed, several that have been previously studied (vorinostat, panobinostat, and β-cyclodextrin significantly lowered the relative amount of unesterified cellular cholesterol, consistent with earlier observations. In addition, a novel potential treatment, rapamycin, likewise alleviated the NPC phenotype. We also studied combinations of effective compounds with β-cyclodextrin; the addition of β-cyclodextrin significantly enhanced the cholesterol-lowering activity of vorinostat and panobinostat, but had mixed effects with rapamycin. Collectively, these results may provide a basis for the eventual development of improved NPC therapies.

Pricing Chinese Convertible Bonds with Dynamic Credit Risk

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Ping Li

2014-01-01

Full Text Available To price convertible bonds more precisely, least squares Monte Carlo (LSM method is used in this paper for its advantage in handling the dependence of derivatives on the path, and dynamic credit risk is used to replace the fixed one to make the value of convertible bonds reflect the real credit risk. In the empirical study, we price convertible bonds based on static credit risk and dynamic credit risk, respectively. Empirical results indicate that the ICBC convertible bond has been overpriced, resulting from the underestimation of credit risk. In addition, when there is an issue of dividend, the conversion price will change in China's convertible bonds, while it does not change in the international convertible bonds. So we also empirically study the difference between the convertible bond's prices by assuming whether the conversion price changes or not.

Oxidative Stress: A Pathogenic Mechanism for Niemann-Pick Type C Disease

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Mary Carmen Vázquez

2012-01-01

Full Text Available Niemann-Pick type C (NPC disease is a neurovisceral atypical lipid storage disorder involving the accumulation of cholesterol and other lipids in the late endocytic pathway. The pathogenic mechanism that links the accumulation of intracellular cholesterol with cell death in NPC disease in both the CNS and the liver is currently unknown. Oxidative stress has been observed in the livers and brains of NPC mice and in different NPC cellular models. Moreover, there is evidence of an elevation of oxidative stress markers in the serumof NPC patients. Recent evidence strongly suggests that mitochondrial dysfunction plays an important role in NPC pathogenesis and that mitochondria could be a significant source of oxidative stress in this disease. In this context, the accumulation of vitamin E in the late endosomal/lysosomal compartments in NPC could lead to a potential decrease of its bioavailability and could be another possible cause of oxidative damage. Another possible source of reactive species in NPC is the diminished activity of different antioxidant enzymes. Moreover, because NPC is mainly caused by the accumulation of free cholesterol, oxidized cholesterol derivatives produced by oxidative stress may contribute to the pathogenesis of the disease.

Gpnmb Is a Potential Marker for the Visceral Pathology in Niemann-Pick Type C Disease.

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André R A Marques

Full Text Available Impaired function of NPC1 or NPC2 lysosomal proteins leads to the intracellular accumulation of unesterified cholesterol, the primary defect underlying Niemann-Pick type C (NPC disease. In addition, glycosphingolipids (GSLs accumulate in lysosomes as well. Intralysosomal lipid accumulation triggers the activation of a set of genes, including potential biomarkers. Transcript levels of Gpnmb have been shown to be elevated in various tissues of an NPC mouse model. We speculated that Gpnmb could serve as a marker for visceral lipid accumulation in NPC disease. We report that Gpnmb expression is increased at protein level in macrophages in the viscera of Npc1nih/nih mice. Interestingly, soluble Gpnmb was also found to be increased in murine and NPC patient plasma. Exposure of RAW264.7 macrophages to the NPC-phenotype-inducing drug U18666A also upregulated Gpnmb expression. Inhibition of GSL synthesis with the glucosylceramide synthase (GCS inhibitor N-butyl-1-deoxynojirimycin prevented U18666A-induced Gpnmb induction and secretion. In summary, we show that Gpnmb is upregulated in NPC mice and patients, most likely due to GSL accumulation.

Device model for pixelless infrared image up-converters based on polycrystalline graphene heterostructures

Science.gov (United States)

Ryzhii, V.; Shur, M. S.; Ryzhii, M.; Karasik, V. E.; Otsuji, T.

2018-01-01

We developed a device model for pixelless converters of far/mid-infrared radiation (FIR/MIR) images into near-infrared/visible (NIR/VIR) images. These converters use polycrystalline graphene layers (PGLs) immersed in the van der Waals materials integrated with a light emitting diode (LED). The PGL serves as an element of the PGL infrared photodetector (PGLIP) sensitive to the incoming FIR/MIR due to the interband absorption. The spatially non-uniform photocurrent generated in the PGLIP repeats (mimics) the non-uniform distribution (image) created by the incident FIR/MIR. The injection of the nonuniform photocurrent into the LED active layer results in the nonuniform NIR/VIR image reproducing the FIR/MIR image. The PGL and the entire layer structure are not deliberately partitioned into pixels. We analyze the characteristics of such pixelless PGLIP-LED up-converters and show that their image contrast transfer function and the up-conversion efficiency depend on the PGL lateral resistivity. The up-converter exhibits high photoconductive gain and conversion efficiency when the lateral resistivity is sufficiently high. Several teams have successfully demonstrated the large area PGLs with the resistivities varying in a wide range. Such layers can be used in the pixelless PGLIP-LED image up-converters. The PGLIP-LED image up-converters can substantially surpass the image up-converters based on the quantum-well infrared photodetector integrated with the LED. These advantages are due to the use of the interband FIR/NIR absorption and a high photoconductive gain in the GLIPs.

Comments, with reply, on 'Parallel resonant converter with LLC-type commutation' by C. Q. Lee et al.

Science.gov (United States)

Hamill, David C.

1991-05-01

In a recent paper by Lee et al. (1989), the authors analyzed a DC-DC converter that they termed the LLC-type PRC (parallel resonant converter). Its resonant network contains three active components-two inductances and a parallel capacitance -and as a consequence the the converter might be expected to have third-order dynamics. But Lee et al. employed a matrix transformation to show that the behavior of the circuit may be represented as a state-plane trajectory, as for a second-order circuit. The purpose of this contribution is to show that the converter has a zero-frequency eigenvalue, associated with undesirable circulating DC. The second-order dynamics exhibited by the third-order converter are explained by an application of Thevenin's theorem. Some aerospace applications of the LLC-type parallel resonant converter (PRC) are discussed. In their reply, the authors show that the circulating direct current does not exist in the practical converter circuit.

Commutation Processes in Multiresonant ZVS Bridge Converter

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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.

Number-to-voltage converter on commutated condensers

International Nuclear Information System (INIS)

Grekhov, Yu.N.

1975-01-01

A code-voltage converter using precision voltage dividers based on commutated capacitors [1] is described which is distinguished by the absence of precision elements. Each digit includes eight field-effect transistors in two 1KT682 microcircuit assemblies and three microcapacitors with a conventional unstable capacitance 6200 pF +- 50%. The converter has a speed of response that is not inferior to that of converters based on R-2R matrices, while in time stability of the characteristics, low interference level, and low output impedance it is superior to such converters

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...

Modulation and control of matrix converter for aerospace application

Science.gov (United States)

Kobravi, Keyhan

In the context of modern aircraft systems, a major challenge is power conversion to supply the aircraft's electrical instruments. These instruments are energized through a fixed-frequency internal power grid. In an aircraft, the available sources of energy are a set of variable-speed generators which provide variable-frequency ac voltages. Therefore, to energize the internal power grid of an aircraft, the variable-frequency ac voltages should be converted to a fixed-frequency ac voltage. As a result, an ac to ac power conversion is required within an aircraft's power system. This thesis develops a Matrix Converter to energize the aircraft's internal power grid. The Matrix Converter provides a direct ac to ac power conversion. A major challenge of designing Matrix Converters for aerospace applications is to minimize the volume and weight of the converter. These parameters are minimized by increasing the switching frequency of the converter. To design a Matrix Converter operating at a high switching frequency, this thesis (i) develops a scheme to integrate fast semiconductor switches within the current available Matrix Converter topologies, i.e., MOSFET-based Matrix Converter, and (ii) develops a new modulation strategy for the Matrix Converter. This Matrix Converter and the new modulation strategy enables the operation of the converter at a switching-frequency of 40kHz. To provide a reliable source of energy, this thesis also develops a new methodology for robust control of Matrix Converter. To verify the performance of the proposed MOSFET-based Matrix Converter, modulation strategy, and control design methodology, various simulation and experimental results are presented. The experimental results are obtained under operating condition present in an aircraft. The experimental results verify the proposed Matrix Converter provides a reliable power conversion in an aircraft under extreme operating conditions. The results prove the superiority of the proposed Matrix

A tapped-inductor buck-boost converter for a multi-DEAP generator energy harvesting system

DEFF Research Database (Denmark)

Dimopoulos, Emmanouil; Munk-Nielsen, Stig

2014-01-01

the effective operational range of the power electronic converter. In this paper, a bidirectional tapped-inductor buck-boost converter is proposed, addressing high-efficient high step-up and high step-down voltage conversion ratios, for energy harvesting applications based on DEAP generators. The effective...... operational range of the converter is extended, by replacing its high-side switch with a string of three serialized MOSFETs, to accommodate the need for high-efficient high-voltage operation. Experiments conducted on a single DEAP generator - part of a quadruple DEAP generator energy harvesting system...... with all elements installed sequentially in the same circular disk with a 90 phase shift - validate the applicability of the proposed converter, demonstrating energy harvesting of 0.26 J, at 0.5 Hz and 60 % delta-strain; characterized by an energy density of 1.25 J per kg of active material....

Soy Pulp Extract Inhibits Angiotensin I-Converting Enzyme (ACE) Activity In Vitro: Evidence for Its Potential Hypertension-Improving Action.

Science.gov (United States)

Nishibori, Naoyoshi; Kishibuchi, Reina; Morita, Kyoji

2017-05-04

Soy pulp, called "okara" in Japanese, is known as a by-product of the production of bean curd (tofu), and expected to contain a variety of biologically active substances derived from soybean. However, the biological activities of okara ingredients have not yet been fully understood, and the effectiveness of okara as a functional food seems necessary to be further evaluated. Then the effect of okara extract on angiotensin I-converting enzyme (ACE) activity was examined in vitro, and the extract was shown to cause the inhibition of ACE activity in a manner depending on its concentration. Kinetic analysis indicated that this enzyme inhibition was accompanied by an increase in the Km value without any change in Vmax. Further studies suggested that putative inhibitory substances contained in the extract might be heat stable and dialyzable, and recovered mostly in the peptide fraction obtained by a spin-column separation and a high performance liquid chromatography (HPLC) fractionation. Therefore, the extract was speculated to contain small-size peptides responsible for the inhibitory effect of okara extract on ACE activity, and could be expected to improve the hypertensive conditions by reducing the production of hypertensive peptide.

Three new DC-to-DC Single-Switch Converters

Directory of Open Access Journals (Sweden)

Barry W. Williams

2017-06-01

Full Text Available This paper presents a new family of three previously unidentified dc-to-dc converters, buck, boost, and buck-boost voltage-transfer-function topologies, which offer advantageous transformer coupling features and low capacitor dc voltage stressing. The three single-switch, single-diode, converters offer the same features as basic dc-to-dc converters, such as the buck function with continuous output current and the boost function with continuous input current. Converter time-domain simulations and experimental results (including transformer coupling support and extol the dc-to-dc converter concepts and analysis presented.

Research on Compensating Power Converter used for Artillery

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Xing Wang

2014-11-01

Full Text Available Aiming at the low efficiency shortage of traditional power supply converter used for artillery, a novel compensating power converter used for artillery was proposed, and its work mode was analyzed. The current expression of inductor was given and work statuses under two working modes were analyzed. Finally an experimental prototype based on DSP was built, the results indicate that the compensating power converter own low current and voltage stress and high efficiency because only part of power pass through the converter, thus, the converter own large potential application value.

Modulation of the tumor microenvironment by Epstein-Barr virus latent membrane protein 1 in nasopharyngeal carcinoma.

Science.gov (United States)

Yoshizaki, Tomokazu; Kondo, Satoru; Endo, Kazuhira; Nakanishi, Yosuke; Aga, Mitsuharu; Kobayashi, Eiji; Hirai, Nobuyuki; Sugimoto, Hisashi; Hatano, Miyako; Ueno, Takayoshi; Ishikawa, Kazuya; Wakisaka, Naohiro

2018-02-01

Latent membrane protein 1 (LMP1) is a primary oncogene encoded by the Epstein-Barr virus, and various portions of LMP1 are detected in nasopharyngeal carcinoma (NPC) tumor cells. LMP1 has been extensively studied since the discovery of its transforming property in 1985. LMP1 promotes cancer cell growth during NPC development and facilitates the interaction of cancer cells with surrounding stromal cells for invasion, angiogenesis, and immune modulation. LMP1 is detected in 100% of pre-invasive NPC tumors and in approximately 50% of advanced NPC tumors. Moreover, a small population of LMP1-expressing cells in advanced NPC tumor tissue is proposed to orchestrate NPC tumor tissue maintenance and development through cancer stem cells and progenitor cells. Recent studies suggest that LMP1 activity shifts according to tumor development stage, but it still has a pivotal role during all stages of NPC development. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Genetic and Chemical Correction of Cholesterol Accumulation and Impaired Autophagy in Hepatic and Neural Cells Derived from Niemann-Pick Type C Patient-Specific iPS Cells

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Dorothea Maetzel

2014-06-01

Full Text Available Niemann-Pick type C (NPC disease is a fatal inherited lipid storage disorder causing severe neurodegeneration and liver dysfunction with only limited treatment options for patients. Loss of NPC1 function causes defects in cholesterol metabolism and has recently been implicated in deregulation of autophagy. Here, we report the generation of isogenic pairs of NPC patient-specific induced pluripotent stem cells (iPSCs using transcription activator-like effector nucleases (TALENs. We observed decreased cell viability, cholesterol accumulation, and dysfunctional autophagic flux in NPC1-deficient human hepatic and neural cells. Genetic correction of a disease-causing mutation rescued these defects and directly linked NPC1 protein function to impaired cholesterol metabolism and autophagy. Screening for autophagy-inducing compounds in disease-affected human cells showed cell type specificity. Carbamazepine was found to be cytoprotective and effective in restoring the autophagy defects in both NPC1-deficient hepatic and neuronal cells and therefore may be a promising treatment option with overall benefit for NPC disease.

Study on a Novel High-Efficiency Bridgeless PFC Converter

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Cao Taiqiang

2014-01-01

Full Text Available In order to implement a high-efficiency bridgeless power factor correction converter, a new topology and operation principles of continuous conduction mode (CCM and DC steady-state character of the converter are analyzed, which show that the converter not only has bipolar-gain characteristic but also has the same characteristic as the traditional Boost converter, while the voltage transfer ratio is not related with the resonant branch parameters and switching frequency. Based on the above topology, a novel bridgeless Bipolar-Gain Pseudo-Boost PFC converter is proposed. With this converter, the diode rectifier bridge of traditional AC-DC converter is eliminated, and zero-current switching of fast recovery diode is achieved. Thus, the efficiency is improved. Next, we also propose the one-cycle control policy of this converter. Finally, experiments are provided to verify the accuracy and feasibility of the proposed converter.

Power density investigation on the press-pack IGBT 3L-HB-VSCs applied to large wind turbine

DEFF Research Database (Denmark)

Senturk, Osman Selcuk; Munk-Nielsen, Stig; Teodorescu, Remus

2011-01-01

capabilities, DC capacitor sizes, converter cabinet volumes of the three 3LHB- VSCs utilizing press-pack IGBTs are investigated in order to quantify and compare the power densities of the 3L-HB-VSCs employed as grid-side converters. Also, the suitable transformer types for the 3L-HB-VSCs are determined......With three different DC-side and AC-side connections, the three-level H-bridge voltage source converters (3L-HB-VSCs) are alternatives to 3L neutral-point-clamped VSCs (3L-NPC-VSCs) for interfacing large wind turbines with electricity grids. In order to assess their feasibility for large wind...... turbines, they should be investigated in terms of power density, which is one of the most important design criteria for wind turbine converters due to turbine nacelle space limitation. In this study, by means of the converter electro-thermal models based on the converter characteristics, the power...

Synchronous Control of Modular Multilevel Converters

DEFF Research Database (Denmark)

Oleschuk, Valentin; Blaabjerg, Frede; Bose, Bimal K.

2002-01-01

A novel method of direct synchronous pulsewidth modulation (PWM) is applied for control of modular multilevel converters consisting from three standard triphase inverter modules along with an 0.33 p.u. output transformer. The proposed method provides synchronisation of the voltage waveforms...... 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...

Analytical Comparison of Dual-Input Isolated dc-dc Converter with an ac or dc Inductor for Renewable Energy Systems

DEFF Research Database (Denmark)

Zhang, Zhe; Mira Albert, Maria del Carmen; Andersen, Michael A. E.

2017-01-01

This paper presents two configurations of dualinput (DI) or three-port (TPC) isolated dc-dc converters for hybrid renewable energy systems such as photovoltaics and batteries. These two converters are derived by integrating an interleaved boost converter and a single-active bridge converter...... and control perspective, distinct in operation principles, voltage/power transfer functions, loss distributions, soft-switching constraints, and power efficiency under the same operating conditions. Moreover, the inductor design differs greatly between these two cases. In this paper, a comprehensive...

Quantitative Structure-Activity Relationship Modeling Coupled with Molecular Docking Analysis in Screening of Angiotensin I-Converting Enzyme Inhibitory Peptides from Qula Casein Hydrolysates Obtained by Two-Enzyme Combination Hydrolysis.

Science.gov (United States)

Lin, Kai; Zhang, Lanwei; Han, Xue; Meng, Zhaoxu; Zhang, Jianming; Wu, Yifan; Cheng, Dayou

2018-03-28

In this study, Qula casein derived from yak milk casein was hydrolyzed using a two-enzyme combination approach, and high angiotensin I-converting enzyme (ACE) inhibitory activity peptides were screened by quantitative structure-activity relationship (QSAR) modeling integrated with molecular docking analysis. Hydrolysates (casein presents an excellent source to produce ACE inhibitory peptides.

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.

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

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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.

Telomerase Activity Impacts on Epstein-Barr Virus Infection of AGS Cells

Science.gov (United States)

Rac, Jürgen; Haas, Florian; Schumacher, Andrina; Middeldorp, Jaap M.; Delecluse, Henri-Jacques; Speck, Roberto F.

2015-01-01

The Epstein-Barr virus (EBV) is transmitted from host-to-host via saliva and is associated with epithelial malignancies including nasopharyngeal carcinoma (NPC) and some forms of gastric carcinoma (GC). Nevertheless, EBV does not transform epithelial cells in vitro where it is rapidly lost from infected primary epithelial cells or epithelial tumor cells. Long-term infection by EBV, however, can be established in hTERT-immortalized nasopharyngeal epithelial cells. Here, we hypothesized that increased telomerase activity in epithelial cells enhances their susceptibility to infection by EBV. Using HONE-1, AGS and HEK293 cells we generated epithelial model cell lines with increased or suppressed telomerase activity by stable ectopic expression of hTERT or of a catalytically inactive, dominant negative hTERT mutant. Infection experiments with recombinant prototypic EBV (rB95.8), recombinant NPC EBV (rM81) with increased epithelial cell tropism compared to B95.8, or recombinant B95.8 EBV with BZLF1-knockout that is not able to undergo lytic replication, revealed that infection frequencies positively correlate with telomerase activity in AGS cells but also partly depend on the cellular background. AGS cells with increased telomerase activity showed increased expression mainly of latent EBV genes, suggesting that increased telomerase activity directly acts on the EBV infection of epithelial cells by facilitating latent EBV gene expression early upon virus inoculation. Thus, our results indicate that infection of epithelial cells by EBV is a very selective process involving, among others, telomerase activity and cellular background to allow for optimized host-to-host transmission via saliva. PMID:25856387

Adaptive electrothermal protection of power converters

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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.

Nonlinear control of voltage source converters in AC-DC power system.

Science.gov (United States)

Dash, P K; Nayak, N

2014-07-01

This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Generalized model of a bidirectional DC-DC converter

Science.gov (United States)

Hinov, Nikolay; Arnaudov, Dimitar; Penev, Dimitar

2017-12-01

The following paperwork presents models of bidirectional converters. A classic bidirectional converter and a new bidirectional circuit based on a ZCS resonant converter are investigated and compared. The developed models of these converters allow comparison between their characteristics showing their advantages and disadvantages. The models allow precise models of energy storage elements to be implemented as well, which is useful for examination of energy storage systems.

A three-port direct current converter

DEFF Research Database (Denmark)

2016-01-01

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......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...

Passive regenerative snubber cell applied to isolated DCM SEPIC converter

NARCIS (Netherlands)

Tibola, G.; Lemmen, E.; Duarte, J.L.

Isolated converter such as SEPIC has a high voltage stress in the main switch due to transformer leakage inductance. To solve this issue an active or passive clamp action is necessary. The common passive solution based on a RCD snubber is simple but impractical when the value of the leakage

Evolution of the SPS Power Converter Controls towards the LHC Era

CERN Document Server

Brazier, J.C.L.; Semanaz, P.

2001-01-01

By the end of the nineties, the power converter control system (Mugef) of the CERN proton accelerator (SPS) had undergone a complete modernization. This resulted in newly developed hardware for function generation, measurement and I/O in a VME environment, under the LynxOS real-time operating system. This has provided a platform on which extensions can be developed for future operation in the Large Hadron Collider (LHC) era. This paper describes some of these extensions, in particular a fast Surveillance and Interlock system for monitoring the power converter output currents. This will be mandatory for the safe operation of the SPS transfer lines TI2 & TI8 to LHC and for similar applications in the future. The strategies employed to cope with various failure modes of the power converters and the timely activation of the interlock are outlined. The new SPS controls infrastructure now under development, will give rise to new modes of operation for the Mugef systems. Integration with the proposed middleware ...

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...

Near-Shore Floating Wave Energy Converters

DEFF Research Database (Denmark)

Ruol, Piero; Zanuttigh, Barbara; Martinelli, Luca

2011-01-01

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......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...

Novel family of quasi-Z-source DC/DC converters derived from current-fed push-pull converters

DEFF Research Database (Denmark)

Chub, Andrii; Husev, Oleksandr; Vinnikov, Dmitri

2014-01-01

This paper is devoted to the step-up quasi-Z-source dc/dc push-pull converter family. The topologies in the family are derived from the isolated boost converter family by replacing input inductors with the quasi-Z-source network. Two new topologies are proposed, analyzed and compared. Theoretical...

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.

Niemann-Pick C1-deficient mice lacking sterol O-acyltransferase 2 have less hepatic cholesterol entrapment and improved liver function.

Science.gov (United States)

Lopez, Adam M; Jones, Ryan Dale; Repa, Joyce J; Turley, Stephen D

2018-06-07

Cholesteryl esters are generated at multiple sites in the body by sterol O-acyltransferase 1 (SOAT1) or sterol O-acyltransferase 2 (SOAT2) in various cell types, and lecithin cholesterol acyltransferase (LCAT) in plasma. Esterified cholesterol (EC) and triacylglycerol (TAG) contained in lipoproteins cleared from the circulation via receptor-mediated or bulk-phase endocytosis are hydrolyzed by lysosomal acid lipase (LAL) within the late endosomal/lysosomal (E/L) compartment. Then, through the successive actions of Niemann-Pick C2 (NPC2) and Niemann-Pick C1 (NPC1), unesterified cholesterol (UC) is exported from the E/L compartment to the cytosol. Mutations in either NPC1 or NPC2 lead to continuing entrapment of UC in all organs, resulting in multisystem disease which includes hepatic dysfunction and in some cases liver failure. These studies investigated primarily whether elimination of SOAT2 in NPC1-deficient mice impacted hepatic UC sequestration, inflammation, and transaminase activities. Measurements were made in 7 wk-old mice fed a low-cholesterol chow diet or one enriched with cholesterol starting 2 wk before study. In the chow-fed mice, NPC1:SOAT2 double knockouts, compared to their littermates lacking only NPC1, had 20% less liver mass, 28% lower hepatic UC concentrations, and plasma ALT and AST activities that were decreased by 48% and 36%, respectively. mRNA expression levels for several markers of inflammation were all significantly lower in the NPC1 mutants lacking SOAT2. The existence of a new class of potent and selective SOAT2 inhibitors provides an opportunity for exploring if suppression of this enzyme could potentially become an adjunctive therapy for liver disease in NPC1 deficiency.

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 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...

Intracellular transport of low density lipoprotein-derived cholesterol is defective in Niemann-Pick type C fibroblasts

International Nuclear Information System (INIS)

Liscum, L.; Ruggiero, R.M.; Faust, J.R.

1989-01-01

Niemann-Pick disease type C (NPC) is characterized by substantial intracellular accumulation of unesterified cholesterol. The accumulation of unesterified cholesterol in NPC fibroblasts cultured with low density lipoprotein (LDL) appears to result from the inability of LDL to stimulate cholesterol esterification in addition to impaired LDL-mediated downregulation of LDL receptor activity and cellular cholesterol synthesis. Although a defect in cholesterol transport in NPC cells has been inferred from previous studies, no experiments have been reported that measure the intracellular movement of LDL-cholesterol specifically. We have used four approaches to assess intracellular cholesterol transport in normal and NPC cells and have determined the following: (a) mevinolin-inhibited NPC cells are defective in using LDL-cholesterol for growth. However, exogenously added mevalonate restores cell growth equally in normal and NPC cells; (b) the transport of LDL-derived [3H]cholesterol to the plasma membrane is slower in NPC cells, while the rate of appearance of [3H]acetate-derived, endogenously synthesized [3H]cholesterol at the plasma membrane is the same for normal and NPC cells; (c) in NPC cells, LDL-derived [3H]cholesterol accumulates in lysosomes to higher levels than normal, resulting in defective movement to other cell membranes; and (d) incubation of cells with LDL causes an increase in cholesterol content of NPC lysosomes that is threefold greater than that observed in normal lysosomes. Our results indicate that a cholesterol transport defect exists in NPC that is specific for LDL-derived cholesterol

A novel power converter for photovoltaic applications

Science.gov (United States)

Yuvarajan, S.; Yu, Dachuan; Xu, Shanguang

A simple and economical power conditioner to convert the power available from solar panels into 60 Hz ac voltage is described. The raw dc voltage from the solar panels is converted to a regulated dc voltage using a boost converter and a large capacitor and the dc output is then converted to 60 Hz ac using a bridge inverter. The ratio between the load current and the short-circuit current of a PV panel at maximum power point is nearly constant for different insolation (light) levels and this property is utilized in designing a simple maximum power point tracking (MPPT) controller. The controller includes a novel arrangement for sensing the short-circuit current without disturbing the operation of the PV panel and implementing MPPT. The switching losses in the inverter are reduced by using snubbers. The results obtained on an experimental converter are presented.

Complex lipid trafficking in Niemann-Pick disease type C.

Science.gov (United States)

Vanier, Marie T

2015-01-01

Niemann-Pick disease type C (NPC) is an atypical lysosomal storage disease resulting from mutations in one of two genes, either NPC1 or NPC2. Although a neurovisceral disorder, it is above all a neurodegenerative disease in the vast majority of patients. Not an enzyme deficiency, it is currently conceived as a lipid trafficking disorder. Impaired egress of cholesterol from the late endosomal/lysosomal (LE/L) compartment is a specific and key element of the pathogenesis, but other lipids, more specially sphingolipids, are also involved, and there are indications for further abnormalities. The full function of the NPC1 and NPC2 proteins is still unclear. This review provides a reappraisal of lipid storage and lysosomal enzymes activities in tissues/cells from NPC patients and animal models. It summarizes the current knowledge on the NPC1 and NPC2 proteins and their function in transport of cholesterol within the late endosomal-lysosomal compartment, with emphasis on differences between systemic organs and the brain; it also discusses regulation by membrane lipids of the NPC2-mediated cholesterol trafficking, interplay between cholesterol and sphingomyelin, the metabolic origin of glycosphingolipids stored in brain, and the putative role of free sphingoid bases in pathogenesis. Brief mention is finally made of diseases affecting other genes that were very recently shown to impact the "NPC pathway".

Grid Filter Design for a Multi-Megawatt Medium-Voltage Voltage Source Inverter

DEFF Research Database (Denmark)

Rockhill, A.A.; Liserre, Marco; Teodorescu, Remus

2011-01-01

This paper describes the design procedure and performance of an LCL grid filter for a medium-voltage neutral point clamped (NPC) converter to be adopted for a multimegawatt wind turbine. The unique filter design challenges in this application are driven by a combination of the medium voltage...... converter, a limited allowable switching frequency, component physical size and weight concerns, and the stringent limits for allowable injected current harmonics. Traditional design procedures of grid filters for lower power and higher switching frequency converters are not valid for a multi......-megawatt filter connecting a medium-voltage converter switching at low frequency to the electric grid. This paper demonstrates a frequency domain model based approach to determine the optimum filter parameters that provide the necessary performance under all operating conditions given the necessary design...

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.

New DC/DC High Step Up Isolated Converter with ZVS

Directory of Open Access Journals (Sweden)

Ehsan Movahedi

2014-10-01

Full Text Available In this paper we presents a soft switch sepic, flyback converter. At first the converter have hard switching in main switch and completely analysis then added auxiliary circuit for soft switching Auxiliary circuit in the converter is not only soft switching condition for the main switch but also prevents the spike voltage across the main switch when turned off that because leakage inductance. Therefore, the proposed converter efficiency in comparison with the previous converters increased and voltage stress on the main switch is reduced. Also the auxiliary switch in the converter have soft switching and thereby decrese losses. this converter Control with pwm.These converter have higher efficiency than the similar converters and the cost is low. Auxiliary circuit in the converter is not only soft switching condition for the main switch but also prevents the spike voltage across the main switch when turned off that because leakage inductance. Therefore, the proposed converter efficiency in comparison with the previous converters increased and voltage stress on the main switch is reduced.

Angiotensin-converting enzyme-inhibitory activity in protein hydrolysates from normal and anthracnose disease-damaged Phaseolus vulgaris seeds.

Science.gov (United States)

Hernández-Álvarez, Alan Javier; Carrasco-Castilla, Janet; Dávila-Ortiz, Gloria; Alaiz, Manuel; Girón-Calle, Julio; Vioque-Peña, Javier; Jacinto-Hernández, Carmen; Jiménez-Martínez, Cristian

2013-03-15

Bean seeds are an inexpensive source of protein. Anthracnose disease caused by the fungus Colletotrichum lindemuthianum results in serious losses in common bean (Phaseolus vulgaris L.) crops worldwide, affecting any above-ground plant part, and protein dysfunction, inducing the synthesis of proteins that allow plants to improve their stress tolerance. The aim of this study was to evaluate the use of beans damaged by anthracnose disease as a source of peptides with angiotensin-converting enzyme (ACE-I)-inhibitory activity. Protein concentrates from beans spoiled by anthracnose disease and from regular beans as controls were prepared by alkaline extraction and precipitation at isolelectric pH and hydrolysed using Alcalase 2.4 L. The hydrolysates from spoiled beans had ACE-I-inhibitory activity (IC(50) 0.0191 mg protein mL(-1)) and were very similar to those from control beans in terms of ACE-I inhibition, peptide electrophoretic profile and kinetics of hydrolysis. Thus preparation of hydrolysates using beans affected by anthracnose disease would allow for revalorisation of this otherwise wasted product. The present results suggest the use of spoiled bean seeds, e.g. anthracnose-damaged beans, as an alternative for the isolation of ACE-I-inhibitory peptides to be further introduced as active ingredients in functional foods. © 2012 Society of Chemical Industry.

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.

Step-Up DC-DC Power Converter

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a step-up DC-DC power converter which comprises a primary side circuit and a secondary side circuit coupled through a galvanic isolation barrier. The primary side circuit comprises a positive and a negative input terminal for receipt of an input voltage and an input...... being charged from the input voltage and discharged to the output capacitor through the galvanic isolation barrier in accordance with a switch control signal to produce the converter output voltage. The step-up DC-DC power converter comprises an electrical short-circuit connection across the galvanic...

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.

Angiotensin I converting enzyme inhibitory activity and antihypertensive effect in spontaneously hypertensive rats of cobia (Rachycentron canadum) head papain hydrolysate.

Science.gov (United States)

Yang, Ping; Jiang, Yuchuan; Hong, Pengzhi; Cao, Wenhong

2013-06-01

Cobia head protein hydrolysate (CHPH) with angiotensin I converting enzyme (ACE) inhibitory activity was prepared with papain. The 3 kDa ultrafiltration filtrate CHPH-IV of the hydrolysate exerted a potent ACE inhibitory activity with IC50 being 0.24 mg/mL. The fractions with molecular weight located between 1749 Da and 173 Da represented up 66.96% of CHPH-IV, and those between 494 Da and 173 Da represented up 31.37% of CHPH-IV. It was found that the ACE inhibitory activity of CHPH-IV was intensified from IC50 0.24 mg/mL to 0.17 mg/mL after incubation with gastrointestinal proteases. The CHPH-IV significantly decreased the systolic blood pressure in a dose-dependent manner after oral administration to spontaneously hypertensive rats (SHR) at dose of 150 mg/kg, 600 mg/kg and 1200 mg/kg body weight. These results suggested that CHPH-IV from cobia head protein hydrolysate by papain could serve as a source of peptides with antihypertensive activity in functional food industry.

Test and Analysis of Metallurgical Converter Equipment

Directory of Open Access Journals (Sweden)

Shan Pang

2013-05-01

Full Text Available Oxygen top-blow converter is the main equipment in steel making, and its work reliability decides the security and economy of steel production. Therefore, how to design and test analysis of convertor has been an important subject of industry research. Geometric modelling and structure analysis of converter tilting device by using Pro/E program .The design Principle, basic design structure were analyzed in detail. The computer simulation software of metallurgical converter equipment and how to use it were introduced .It developed by VC++ software. The position of barycentre and moment curve in No.3 and No.4 are calculated. The converter acceleration down dip can be resolved by comparing the moment curve and center curve.

The rise and demise of the convertible arbitrage strategy

NARCIS (Netherlands)

Loncarski, I.; Ter Horst, J.R.; Veld, C.H.

2009-01-01

This article analyzes convertible arbitrage, one of the most successful hedge fund strategies. The aim of the strategy is to exploit underpricing of convertible bonds by taking a long position in a convertible and a short position in the underlying asset. The authors find that convertible bonds are

Electrostatic direct energy converter performance and cost scaling laws

International Nuclear Information System (INIS)

Hoffman, M.A.

1977-08-01

This study is concerned with electrostatic type direct energy converters for direct recovery of a large fraction of the plasma ion energy from fusion reactors. Simplified equations are presented for each of the important loss mechanisms in both single-stage direct converters and multistage ''Venetian Blind'' type direct converters. These equations can be used to estimate the efficiency and electric power output of the direct converter subsystem. Scaling relations for the cost of each major component in the direct converter subsystem are also given; these include the vacuum tank, direct converter modules, the DC power conditioning equipment, cryogenic vacuum pumping system and the thermal bottoming plant. The performance and cost scaling laws have been developed primarily for use in overall fusion power plant systems codes. However, to illustrate their utility, cost-effectiveness studies of two specific reference direct converter designs are presented in terms of the specific capital costs (i.e., the capital cost per unit electric power produced) for the Direct Converter Subsystem alone. Some examples of design improvements which can significantly reduce the specific capital costs of the Direct Converter Subsystem are also given

Methylation associated inactivation of RASSF1A and its synergistic effect with activated K-Ras in nasopharyngeal carcinoma

Directory of Open Access Journals (Sweden)

Yu Jing

2009-12-01

Full Text Available Abstract Background Epigenetic silencing of tumor suppressor genes associated with promoter methylation is considered to be a hallmark of oncogenesis. RASSF1A is a candidate tumor suppressor gene which was found to be inactivated in many human cancers. Although we have had a prelimilary cognition about the function of RASSF1A, the exact mechanisms about how RASSF1A functions in human cancers were largely unknown. Moreover, the effect of mutated K-Ras gene on the function of RASSF1A is lacking. The aim of this study was to investigate the expression profile and methylation status of RASSF1A gene, and to explore its concrete mechanisms as a tumor suppressor gene in Nasopharyngeal Carcinoma. Methods We examined the expression profile and methylation status of RASSF1A in two NPC cell lines, 38 primary nasopharyngeal carcinoma and 14 normal nasopharyngeal epithelia using RT-PCR and methylated specific PCR(MSP respectively. 5-aza-dC was then added to confirm the correlation between hypermethylation status and inactivation of RASSF1A. The NPC cell line CNE-2 was transfected with exogenous pcDNA3.1(+/RASSF1A plasmid in the presence or absence of mutated K-Ras by liposome-mediated gene transfer method. Flow cytometry was used to examine the effect of RASSF1A on cell cycle modulation and apoptosis. Meanwhile, trypan blue dye exclusion assays was used to detect the effect of RASSF1A transfection alone and the co-transfection of RASSF1A and K-Ras on cell proliferation. Results Promoter methylation of RASSF1A could be detected in 71.05% (27/38 of NPC samples, but not in normal nasopharyngeal epithelia. RASSF1A expression in NPC primary tumors was lower than that in normal nasopharyngeal epithelial (p p p p Conclusion Expression of RASSF1A is down-regulated in NPC due to the hypermethylation of promoter. Exogenous expression of RASSF1A is able to induce growth inhibition effect and apoptosis in tumor cell lines, and this effect could be enhanced by activated

MOF-derived Cu/nanoporous carbon composite and its application for electro-catalysis of hydrogen evolution reaction

International Nuclear Information System (INIS)

Raoof, Jahan-Bakhsh; Hosseini, Sayed Reza; Ojani, Reza; Mandegarzad, Sakineh

2015-01-01

In this work, metal-organic framework Cu_3(BTC)_2 [BTC = 1,3,5-benzenetricarboxylate] (commonly known as MOF-199 or HKUST-1), is used as porous template for preparation of a Cu/nanoporous carbon composite. The MOF-derived Cu/nanoporous carbon composite (Cu/NPC composite) is synthesized by direct carbonization of the MOF-199 without any carbon precursor additive. The physical characterization of the solid catalyst is achieved by using a variety of different techniques, including XRD (X-ray powder diffraction), scanning electron microscopy, thermo-gravimetric analysis, and nitrogen physisorption measurements. The electrochemical results have shown that the Cu/NPC composite modified glassy carbon electrode (Cu/NPC/GCE) as a non-platinum electrocatalyst exhibited favorable catalytic activity for hydrogen evolution reaction, in spite of high resistance to faradic process. This behavior can be attributed to existence of Cu metal confirmed by XRD and/or high effective pore surface area (1025 m"2 g"−"1) in the Cu/NPC composite. The electron transfer coefficient and exchange current density for the Cu/NPC/GCE is calculated by Tafel plot at about 0.34 and 1.2 × 0"−"3 mAcm"−"2, respectively. - Graphical abstract: Metal organic framework-derived Cu/nanoporous carbon composite (Cu/NPC composite) was prepared by direct carbonization of MOF-199 without addition of any carbon source at 900 °C. The Cu/NPC/GCE demonstrated an excellent electrocatalytic activity towards hydrogen evolution reaction compared with bare GCE. - Highlights: • MDNPC (MOF-199 derived nanoporous carbon) is prepared by direct carbonization. • MOF-199 is utilized as a template without addition of carbon resource. • The MDNPC has a good electrocatalytic activity in hydrogen evolution reaction. • High BET surface area and hydrogen adsorption property improved catalyst activity.

Featured Article: Isolation, characterization, and cultivation of human hepatocytes and non-parenchymal liver cells

Science.gov (United States)

Pfeiffer, Elisa; Kegel, Victoria; Zeilinger, Katrin; Hengstler, Jan G; Nüssler, Andreas K; Seehofer, Daniel

2015-01-01

Primary human hepatocytes (PHH) are considered to be the gold standard for in vitro testing of xenobiotic metabolism and hepatotoxicity. However, PHH cultivation in 2D mono-cultures leads to dedifferentiation and a loss of function. It is well known that hepatic non-parenchymal cells (NPC), such as Kupffer cells (KC), liver endothelial cells (LEC), and hepatic stellate cells (HSC), play a central role in the maintenance of PHH functions. The aims of the present study were to establish a protocol for the simultaneous isolation of human PHH and NPC from the same tissue specimen and to test their suitability for in vitro co-culture. Human PHH and NPC were isolated from tissue obtained by partial liver resection by a two-step EDTA/collagenase perfusion technique. The obtained cell fractions were purified by Percoll density gradient centrifugation. KC, LEC, and HSC contained in the NPC fraction were separated using specific adherence properties and magnetic activated cell sorting (MACS®). Identified NPC revealed a yield of 1.9 × 106 KC, 2.7 × 105 LEC and 4.7 × 105 HSC per gram liver tissue, showing viabilities >90%. Characterization of these NPC showed that all populations went through an activation process, which influenced the cell fate. The activation of KC strongly depended on the tissue quality and donor anamnesis. KC became activated in culture in association with a loss of viability within 4–5 days. LEC lost specific features during culture, while HSC went through a transformation process into myofibroblasts. The testing of different culture conditions for HSC demonstrated that they can attenuate, but not prevent dedifferentiation in vitro. In conclusion, the method described allows the isolation and separation of PHH and NPC in high quality and quantity from the same donor. PMID:25394621

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....

Towards radiation hard converter material for SiC-based fast neutron detectors

Science.gov (United States)

Tripathi, S.; Upadhyay, C.; Nagaraj, C. P.; Venkatesan, A.; Devan, K.

2018-05-01

In the present work, Geant4 Monte-Carlo simulations have been carried out to study the neutron detection efficiency of the various neutron to other charge particle (recoil proton) converter materials. The converter material is placed over Silicon Carbide (SiC) in Fast Neutron detectors (FNDs) to achieve higher neutron detection efficiency as compared to bare SiC FNDs. Hydrogenous converter material such as High-Density Polyethylene (HDPE) is preferred over other converter materials due to the virtue of its high elastic scattering reaction cross-section for fast neutron detection at room temperature. Upon interaction with fast neutrons, hydrogenous converter material generates recoil protons which liberate e-hole pairs in the active region of SiC detector to provide a detector signal. The neutron detection efficiency offered by HDPE converter is compared with several other hydrogenous materials viz., 1) Lithium Hydride (LiH), 2) Perylene, 3) PTCDA . It is found that, HDPE, though providing highest efficiency among various studied materials, cannot withstand high temperature and harsh radiation environment. On the other hand, perylene and PTCDA can sustain harsh environments, but yields low efficiency. The analysis carried out reveals that LiH is a better material for neutron to other charge particle conversion with competent efficiency and desired radiation hardness. Further, the thickness of LiH has also been optimized for various mono-energetic neutron beams and Am-Be neutron source generating a neutron fluence of 109 neutrons/cm2. The optimized thickness of LiH converter for fast neutron detection is found to be ~ 500 μm. However, the estimated efficiency for fast neutron detection is only 0.1%, which is deemed to be inadequate for reliable detection of neutrons. A sensitivity study has also been done investigating the gamma background effect on the neutron detection efficiency for various energy threshold of Low-Level Discriminator (LLD). The detection

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

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...

Efficiency and reliability improvement in wind turbine converters by grid converter adaptive control

DEFF Research Database (Denmark)

Trintis, Ionut; Munk-Nielsen, Stig; Abrahamsen, Flemming

2013-01-01

This paper presents a control method that reduces the losses in wind turbine converters adaptively controlling the grid converter. The dc-link voltage adapts its reference based on the system state and therefore reduces the stored energy, and is therefore kept at the minimum necessary for the grid...... and generator side. Operating in this way, the electrical and thermal stress factors are decreased on the power electronic devices, increasing their lifetime. The simulation results using this method show efficiency increase and devices temperature cycles slightly decreased. Experimental results on a wind...... turbine power stack shows efficiency increase in the high power region....

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.

Parallel resonant converter with LLC-type commutation

Science.gov (United States)

Lee, C. Q.; Liu, Rui; Batarseh, Issa

1989-11-01

It is shown that by using a proper transformation of state variables, the third-order system of the parallel resonant converter (PRC) with LLC-type commutation can be analyzed by means of a two-dimensional state-plane diagram. A set of characteristic curves which can be used for the converter design is derived from the analysis. It is shown from these curves that the converter possesses more desirable features than the conventional PRC.

Fuzzy Controlled Parallel AC-DC Converter for PFC

Directory of Open Access Journals (Sweden)

M Subba Rao

2011-01-01

Full Text Available Paralleling of converter modules is a well-known technique that is often used in medium-power applications to achieve the desired output power by using smaller size of high frequency transformers and inductors. In this paper, a parallel-connected single-phase PFC topology using flyback and forward converters is proposed to improve the output voltage regulation with simultaneous input power factor correction (PFC and control. The goal of the control is to stabilize the output voltage of the converter against the load variations. The paper presents the derivation of fuzzy control rules for the dc/dc converter circuit and control algorithm for regulating the dc/dc converter. This paper presents a design example and circuit analysis for 200 W power supply. The proposed approach offers cost effective, compact and efficient AC/DC converter by the use of parallel power processing. MATLAB/SIMULINK is used for implementation and simulation results show the performance improvement.

Conception and realization of a multichannel amplitude converter

International Nuclear Information System (INIS)

Bendebiche, L.

1992-11-01

A compact Analog to Digital Converter system suitable for high resolution γ-ray analysers has been developed based on the ADADC84 12-bit converter from Analog Devices. The converter was equipped with a peak detector and a stretcher, and with a memory card providing the sliding scale circuits, the lower threshold, the channel number identification and the zero suppression. The conversion time is 10 μs and the differential non linearity is less than ±1% for a 12-bit resolution. The converter consists of a 12-bit spectroscopy analog-to-digital converter (ADC) while the memory card includes a 8K 24-bit buffer memory. The two cards are plugged into a slot of an IBM PC AT and using an emulation software converts the micro-computer into a full-featured pulse height analyser. In data acquisition mode, the cards can operate independently, making the computer free for other tasks. The software offers acquisition control, visualization, data handling functions and various types of result presentation

Effect of inlet cone pipe angle in catalytic converter

Science.gov (United States)

Amira Zainal, Nurul; Farhain Azmi, Ezzatul; Arifin Samad, Mohd

2018-03-01

The catalytic converter shows significant consequence to improve the performance of the vehicle start from it launched into production. Nowadays, the geometric design of the catalytic converter has become critical to avoid the behavior of backpressure in the exhaust system. The backpressure essentially reduced the performance of vehicles and increased the fuel consumption gradually. Consequently, this study aims to design various models of catalytic converter and optimize the volume of fluid flow inside the catalytic converter by changing the inlet cone pipe angles. Three different geometry angles of the inlet cone pipe of the catalytic converter were assessed. The model is simulated in Solidworks software to determine the optimum geometric design of the catalytic converter. The result showed that by decreasing the divergence angle of inlet cone pipe will upsurge the performance of the catalytic converter.

CAS - CERN Accelerator School: Power Converters

CERN Document Server

2015-01-01

These proceedings collate lectures given at the twenty-eighth specialized course organised by the CERN Accelerator School (CAS). The course was held at the Hotel du Parc, Baden, Switzerland from 7 - 14 May 2014, in collaboration with the Paul Scherrer Institute. Following introductory lectures on accelerators and the requirements on power converters, the course covered components and topologies of the different types of power converters needed for particle accelerators. Issues of design, control and exploitation in a sometimes-hostile environment were addressed. Site visits to ABB and PSI provided an insight into state-of-the-art power converter production and operation, while topical seminars completed the programme.

Evaluation of an anti-tumor necrosis factor therapeutic in a mouse model of Niemann-Pick C liver disease.

Directory of Open Access Journals (Sweden)

Melanie Vincent

2010-09-01

Full Text Available Niemann-Pick type C (NPC disease is a lysosomal storage disease characterized by the accumulation of cholesterol and glycosphingolipids. The majority of NPC patients die in their teen years due to progressive neurodegeneration; however, half of NPC patients also suffer from cholestasis, prolonged jaundice, and hepatosplenomegaly. We previously showed that a key mediator of NPC liver disease is tumor necrosis factor (TNF α, which is involved in both proinflammatory and apoptotic signaling cascades. In this study, we tested the hypothesis that blocking TNF action with an anti-TNF monoclonal antibody (CNTO5048 will slow the progression of NPC liver disease.Treatment of wild-type C57BL/6 mice with NPC1-specific antisense oligonucleotides led to knockdown of NPC1 protein expression in the liver. This caused classical symptoms of NPC liver disease, including hepatic cholesterol accumulation, hepatomegaly, elevated serum liver enzymes, and lipid laden macrophage accumulation. In addition, there was a significant increase in the number of apoptotic cells and a proliferation of stellate cells. Concurrent treatment of NPC1 knockdown mice with anti-TNF had no effect on the primary lipid storage or accumulation of lipid-laden macrophages. However, anti-TNF treatment slightly blunted the increase in hepatic apoptosis and stellate cell activation that was seen with NPC1 knockdown.Current therapeutic options for NPC disease are limited. Our results provide proof of principle that pharmacologically blocking the TNF-α inflammatory cascade can slightly reduce certain markers of NPC disease. Small molecule inhibitors of TNF that penetrate tissues and cross the blood-brain barrier may prove even more beneficial.

Scavenger Receptor B1 is a Potential Biomarker of Human Nasopharyngeal Carcinoma and Its Growth is Inhibited by HDL-mimetic Nanoparticles

Science.gov (United States)

Zheng, Ying; Liu, Yanyan; Jin, Honglin; Pan, Shaotao; Qian, Yuan; Huang, Chuan; Zeng, Yixin; Luo, Qingming; Zeng, Musheng; Zhang, Zhihong

2013-01-01

Nasopharyngeal carcinoma (NPC) is a very regional malignant head and neck cancer that has attracted widespread attention for its unique etiology, epidemiology and therapeutic options. To achieve high cure rates in NPC patients, theranostic approaches are actively being pursued and improved efforts remain desirable in identifying novel biomarkers and establishing effective therapeutic approaches with low long-term toxicities. Here, we discovered that the scavenger receptor class B type I (SR-B1) was overexpressed in all investigated NPC cell lines and 75% of NPC biopsies, demonstrating that SR-B1 is a potential biomarker of NPC. Additional functional analysis showed that SR-B1 has great effect on cell motility while showing no significant impact on cell proliferation. As high-density lipoproteins (HDL) exhibit strong binding affinities to SR-B1 and HDL mimetic peptides are reportedly capable of inhibiting tumor growth, we further examined the SR-B1 targeting ability of a highly biocompatible HDL-mimicking peptide-phospholipid scaffold (HPPS) nanocarrier and investigated its therapeutic effect on NPC. Results show that NPC cells with higher SR-B1 expression have superior ability in taking up the core constituents of HPPS. Moreover, HPPS inhibited the motility and colony formation of 5-8F cells, and significantly suppressed the NPC cell growth in nude mice without inducing tumor cell necrosis or apoptosis. These results indicate that HPPS is not only a NPC-targeting nanocarrier but also an effective anti-NPC drug. Together, the identification of SR-B1 as a potential biomarker and the use of HPPS as an effective anti-NPC agent may shed new light on the diagnosis and therapeutics of NPC. PMID:23843895

Advanced Receiver/Converter Experiments for Laser Wireless Power Transmission

Science.gov (United States)

Howell, Joe T.; ONeill, Mark; Fork, Richard

2004-01-01

For several years NASA Marshall Space Flight Center, UAH and ENTECH have been working on various aspects of space solar power systems. The current activity was just begun in January 2004 to further develop this new photovoltaic concentrator laser receiver/converter technology. During the next few months, an improved prototype will be designed, fabricated, and thoroughly tested under laser illumination. The final paper will describe the new concept, present its advantages over other laser receiver/converter approaches (including planar photovoltaic arrays), and provide the latest experiment results on prototype hardware (including the effects of laser irradiance level and cell temperature). With NASA's new human exploration plans to first return to the Moon, and then to proceed to Mars, the new photovoltaic concentrator laser receiver/converter technology could prove to be extremely useful in providing power to the landing sites and other phases of the missions. For example, to explore the scientifically interesting and likely resource-rich poles of the Moon (which may contain water) or the poles of Mars (which definitely contain water and carbon dioxide), laser power beaming could represent the simplest means of providing power to these regions, which receive little or no sunlight, making solar arrays useless there. In summary, the authors propose a paper on definition and experimental results of a novel photovoltaic concentrator approach for collecting and converting laser radiation to electrical power. The new advanced photovoltaic concentrator laser receiver/converter offers higher performance, lighter weight, and lower cost than competing concepts, and early experimental results are confirming the expected excellent Performance levels. After the small prototypes are successfully demonstrated, a larger array with even better performance is planned for the next phase experiments and demonstrations. Thereafter, a near-term flight experiment of the new technology

Sheppard-Taylor Isolated High Boost DC-DC Converter

DEFF Research Database (Denmark)

Chub, Andrii; Siwakoti, Yam Prasad; Vinnikov, Dmitri

2017-01-01

This paper presents a new galvanically isolated step-up dc-dc converter intended for low-power but high step-up applications. The proposed converter is capable of regulating output voltage within a wide range of the input voltage or load variations. In contrast to competitors, the converter can...

Advanced Control Strategy of Back-to-Back PWM Converters in PMSG Wind Power System

Directory of Open Access Journals (Sweden)

Tan Luong Van

2015-01-01

Full Text Available This paper proposes a control scheme of back-to-back PWM converters for the permanent magnet synchronous generator (PMSG wind turbine system. The DC-link voltage can be controlled at the machine-side converter (MSC, while the grid-side converter (GSC controls the grid active power for a maximum power point tracking (MPPT. At the grid fault condition, the DC-link voltage controller is designed using a feedback linearization (FL theory. For the MPPT, a proportional control loop is added to the torque control to reduce the influence of the inertia moment in the wind turbines, which can improve its dynamic performance. The validity of this control algorithm has been verified by the simulation of the 2-MW PMSG wind turbine system.

Advanced converters and reactors

International Nuclear Information System (INIS)

Haefele, W.; Kessler, G.

1984-01-01

As Western Europe and most countries of the Asia-Pacific region (except Australia) have only small natural uranium resources, they must import nuclear fuel from the major uranium supplier countries. The introduction of advanced converter and breeder reactor technology allows a fuel utilization of a factor of 4 to 100 higher than with present low converters (LWRs) and will make uranium-importing countries less vulnerable to price jumps and supply stops in the uranium market. In addition, breeder-reactor technology will open up a potential that can cover world energy requirements for several thousand years. The enormous development costs of advanced converter and breeder technologies can probably be raised only by highly industrialized countries. Those highly industrialized countries that have little or no uranium resources (Western Europe, Japan) will probably be the first to introduce this advanced reactor technology on a commercial scale. A number of small countries and islands will need only small power reactors with inherent safety capabilities, especially in the beginning of their nuclear energy programs. For economic reasons, the fuel cycle services should come from large reprocessing centers of countries having sufficiently large nuclear power programs or from international fuel cycle centers. (author)

Novel zero voltage transition pulse width modulation flyback converter

Science.gov (United States)

Adib, Ehsan; Farzanehfard, Hosein

2010-09-01

In this article, a new zero voltage (ZV) transition flyback converter is introduced which uses a simple auxiliary circuit. In this converter, ZV switching condition is achieved for the converter switch while zero current switching condition is attained for the auxiliary switch. There is no additional voltage and current stress on the main switch. Main diode, auxiliary circuit voltage and current ratings are low. The proposed converter is analysed and design procedure is discussed. The presented experimental results of a prototype converter justify the theoretical analysis.

Large-signal stability analysis of PWM converters

Energy Technology Data Exchange (ETDEWEB)

Huynh, P.T. [Philips Labs., Briarcliff Manor, NY (United States); Cho, B.H. [Seoul National Univ. (Korea, Republic of). Dept. of Electrical Engineering

1995-12-31

Investigation of the effects of existing nonlinearities on the stability of PWM converters is performed. The bilinear structure, the duty cycle saturation, and the opamp saturation are the principal nonlinearities in PWM converters. These nonlinearities are incorporated in the large-signal analytical models of PWM converters, and the basic input-output stability theory is applied to analyze their stability. Design and optimization of the small-signal loop gains to counteract the undesirable nonlinear effects are also discussed.

State-plane analysis of parallel resonant converter

Science.gov (United States)

Oruganti, R.; Lee, F. C.

1985-01-01

A method for analyzing the complex operation of a parallel resonant converter is developed, utilizing graphical state-plane techniques. The comprehensive mode analysis uncovers, for the first time, the presence of other complex modes besides the continuous conduction mode and the discontinuous conduction mode and determines their theoretical boundaries. Based on the insight gained from the analysis, a novel, high-frequency resonant buck converter is proposed. The voltage conversion ratio of the new converter is almost independent of load.

Unregulated Series Resonant Converter for Interlinking DC Nanogrids

DEFF Research Database (Denmark)

Tomas Manez, Kevin; Zhang, Zhe; Ouyang, Ziwei

2017-01-01

bidirectional converter to interlink a 400V DC bus with a 48V DC bus ispresented. The proposed converter is based on a LLC resonant converter operating as a DC transformer at a fixed frequency and duty cycle without any complex control strategy. A clearand simplified design procedure for high efficiency...

Association between angiotensin II receptor gene polymorphism and serum angiotensin converting enzyme (SACE) activity in patients with sarcoidosis.

Science.gov (United States)

Takemoto, Y; Sakatani, M; Takami, S; Tachibana, T; Higaki, J; Ogihara, T; Miki, T; Katsuya, T; Tsuchiyama, T; Yoshida, A; Yu, H; Tanio, Y; Ueda, E

1998-06-01

Serum angiotensin converting enzyme (SACE) is considered to reflect disease activity in sarcoidosis. SACE activity is increased in many patients with active sarcoid lesions. The mechanism for the increased SACE activity in this disease has not been clarified. ACE insertion/deletion (I/D) gene polymorphism has been reported to have an association with SACE levels in sarcoidosis, but no evidence of an association between angiotensin II receptor gene polymorphism and SACE in this disease has been found. A study of the association of angiotensin II receptor gene polymorphisms with sarcoidosis was therefore undertaken. ACE (I/D), angiotensin II type 1 receptor (AGTR1), and angiotensin II type 2 receptor (AGTR2) gene polymorphisms were investigated by polymerase chain reaction (PCR) and SACE levels were measured in three groups of patients: those with sarcoidosis or tuberculosis and normal controls. There was no difference in allele frequency of AGTR1 and AGTR2 polymorphism among the three groups. Neither AGTR1 nor AGTR2 polymorphisms were associated with sarcoidosis. SACE activity was higher in patients with sarcoidosis with the AGTR1 A/C genotype than in others. However, this tendency was not detected in patients with tuberculosis. The AGTR1 allele C is associated with high activity of SACE in patients with sarcoidosis. It is another predisposing factor for high levels of SACE in patients with sarcoidosis and is considered to be an independent factor from the ACE D allele for high levels of SACE in sarcoidosis. This fact could be one of the explanations for the increased SACE activity in sarcoidosis.

SoC Design Approach Using Convertibility Verification

Directory of Open Access Journals (Sweden)

Basu Samik

2008-01-01

Full Text Available Abstract Compositional design of systems on chip from preverified components helps to achieve shorter design cycles and time to market. However, the design process is affected by the issue of protocol mismatches, where two components fail to communicate with each other due to protocol differences. Convertibility verification, which involves the automatic generation of a converter to facilitate communication between two mismatched components, is a collection of techniques to address protocol mismatches. We present an approach to convertibility verification using module checking. We use Kripke structures to represent protocols and the temporal logic to describe desired system behavior. A tableau-based converter generation algorithm is presented which is shown to be sound and complete. We have developed a prototype implementation of the proposed algorithm and have used it to verify that it can handle many classical protocol mismatch problems along with SoC problems. The initial idea for -based convertibility verification was presented at SLA++P '07 as presented in the work by Roopak Sinha et al. 2008.

Activity of serum angiotensin-converting enzyme as a tumour marker of hepatocellular carcinoma.

Science.gov (United States)

Kardum, D; Huskic, J; Fabijanic, D; Banic, M; Buljevac, M; Kujundzic, M; Loncar, B

1999-11-01

Previous studies have pointed to the changes of serum angiotensin-converting enzyme (SACE) values in patients with liver disease and cancer located in different sites. The aim of this study was to determine the changes in SACE values in patients with hepatocellular carcinoma (HCC) and liver cirrhosis. The study comprised 30 patients with HCC (22 men and eight women) of average age 48.6 +/- 9.0 years and 30 patients with liver cirrhosis (21 men, nine women) of average age 49.1 +/- 9.5 years. The control group consisted of 30 healthy volunteers with matching anthropometric characteristics. SACE activity was determined by a spectrophotometric method using synthetic hippuryl-glycyl-glycine as substrate. The mean SACE value was considerably lower in patients with HCC, 22.8 U/ml (95% CI, 22.5-23.9), both those in whom HCC developed in cirrhotic liver (n = 23), 23.7 (22.9-24.5) as well as those with HCC without cirrhosis (n = 7), 21.8 (21.0-22.6), with regard to patients with liver cirrhosis, 37.2 (36.6-37.8) (P SACE value was increased in accordance with the severity of the disease expressed by Child's classification; however, at each stage SACE values were considerably lower in patients with HCC in cirrhotic liver (Child A, 35.8 vs 22.1; Child B, 38.7 vs 24.2; Child C, 40.0 vs 28.3) (P SACE activity. The SACE value was also significantly decreased in patients with HCC whose AFP were not altered. The study has shown that SACE values are low in patients with advanced HCC. It may be helpful in detecting HCC in patients with cirrhosis, where it can be difficult to differentiate between small HCC tumours and regeneration nodules.

High-Feedback Operation of Power Electronic Converters

Directory of Open Access Journals (Sweden)

Gennady Y. Mikhal'chenko

2013-03-01

Full Text Available The purpose of this review is to provide a survey of some of the most important bifurcation phenomena that one can observe in pulse-modulated converter systems when operating with high corrector gain factors. Like other systems with switching control, electronic converter systems belong to the class of piecewise-smooth dynamical systems. A characteristic feature of such systems is that the trajectory is “sewed” together from subsequent discrete parts. Moreover, the transitions between different modes of operation in response to a parameter variation are often qualitatively different from the bifurcations we know for smooth systems. The review starts with an introduction to the concept of border-collision bifurcations and also demonstrates the approach by which the full dynamics of the piecewise-linear, time-continuous system can be reduced to the dynamics of a piecewise-smooth map. We describe the main bifurcation structures that one observes in three different types of converter systems: (1 a DC/DC converter; (2 a multi-level DC/DC converter; and (3 a DC/AC converter. Our focus will be on the bifurcations by which the regular switching dynamics becomes unstable and is replaced by ergodic or resonant periodic dynamics on the surface of a two-dimensional torus. This transition occurs when the feedback gain is increased beyond a certain threshold, for instance in Electronics 2013, 2 114 order to improve the speed and accuracy of the output voltage regulation. For each of the three converter types, we discuss a number of additional bifurcation phenomena, including the formation and reconstruction of multi-layered tori and the appearance of phase-synchronized quasiperiodicity. Our numerical simulations are compared with experimentally observed waveforms.

Research and design of quasi-optical mode converter

International Nuclear Information System (INIS)

Liu Jianwei; Zhao Qing

2013-01-01

This paper presents a quasi-optical mode converter which can convert the output mode of gyrotrons and other high-power microwave oscillators into quasi-Gaussian beam, aiming to achieve transverse output of quasi-Gaussian beam TEM 00 mode. First, we analyze mode propagation in the waveguide and the working mechanism of the Vlasov launcher. Then the radiation fields are calculated using vector diffraction theory. At last a quasi-optical mode converter is designed to convert the 94 GHz, TE 62 mode millimeter wave into quasi-Gaussian beam with programming method. The results prove that quasi-Gaussian mode can be obtained at the output window with a simple Vlasov launcher and two mirrors, and the power transmission efficiency of the quasi-optical mode converter reaches to 87.5%. (authors)

Activation of angiotensin-converting enzyme 2 (ACE2) attenuates allergic airway inflammation in rat asthma model

International Nuclear Information System (INIS)

Dhawale, Vaibhav Shrirang; Amara, Venkateswara Rao; Karpe, Pinakin Arun; Malek, Vajir; Patel, Deep; Tikoo, Kulbhushan

2016-01-01

Angiotensin-I converting enzyme (ACE) is positively correlated to asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS) and is highly expressed in lungs. ACE2, the counteracting enzyme of ACE, was proven to be protective in pulmonary, cardiovascular diseases. In the present study we checked the effect of ACE2 activation in animal model of asthma. Asthma was induced in male wistar rats by sensitization and challenge with ovalbumin and then treated with ACE2 activator, diminazene aceturate (DIZE) for 2 weeks. 48 h after last allergen challenge, animals were anesthetized, blood, BALF, femoral bone marrow lavage were collected for leucocyte count; trachea for measuring airway responsiveness to carbachol; lungs and heart were isolated for histological studies and western blotting. In our animal model, the characteristic features of asthma such as altered airway responsiveness to carbachol, eosinophilia and neutrophilia were observed. Western blotting revealed the increased pulmonary expression of ACE1, IL-1β, IL-4, NF-κB, BCL2, p-AKT, p-p38 and decreased expression of ACE2 and IκB. DIZE treatment prevented these alterations. Intraalveolar interstitial thickening, inflammatory cell infiltration, interstitial fibrosis, oxidative stress and right ventricular hypertrophy in asthma control animals were also reversed by DIZE treatment. Activation of ACE2 by DIZE conferred protection against asthma as evident from biochemical, functional, histological and molecular parameters. To the best of our knowledge, we report for the first time that activation of ACE2 by DIZE prevents asthma progression by altering AKT, p38, NF-κB and other inflammatory markers. - Highlights: • Diminazene aceturate (DIZE), an ACE2 activator prevents ovalbumin-induced asthma. • DIZE acted by upregulating ACE2, downregulating ACE1, MAPKs, markers of inflammation, apoptosis. • DIZE reduced airway inflammation, fibrosis, right ventricular hypertrophy and

Activation of angiotensin-converting enzyme 2 (ACE2) attenuates allergic airway inflammation in rat asthma model

Energy Technology Data Exchange (ETDEWEB)

Dhawale, Vaibhav Shrirang; Amara, Venkateswara Rao; Karpe, Pinakin Arun; Malek, Vajir; Patel, Deep; Tikoo, Kulbhushan, E-mail: tikoo.k@gmail.com

2016-09-01

Angiotensin-I converting enzyme (ACE) is positively correlated to asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS) and is highly expressed in lungs. ACE2, the counteracting enzyme of ACE, was proven to be protective in pulmonary, cardiovascular diseases. In the present study we checked the effect of ACE2 activation in animal model of asthma. Asthma was induced in male wistar rats by sensitization and challenge with ovalbumin and then treated with ACE2 activator, diminazene aceturate (DIZE) for 2 weeks. 48 h after last allergen challenge, animals were anesthetized, blood, BALF, femoral bone marrow lavage were collected for leucocyte count; trachea for measuring airway responsiveness to carbachol; lungs and heart were isolated for histological studies and western blotting. In our animal model, the characteristic features of asthma such as altered airway responsiveness to carbachol, eosinophilia and neutrophilia were observed. Western blotting revealed the increased pulmonary expression of ACE1, IL-1β, IL-4, NF-κB, BCL2, p-AKT, p-p38 and decreased expression of ACE2 and IκB. DIZE treatment prevented these alterations. Intraalveolar interstitial thickening, inflammatory cell infiltration, interstitial fibrosis, oxidative stress and right ventricular hypertrophy in asthma control animals were also reversed by DIZE treatment. Activation of ACE2 by DIZE conferred protection against asthma as evident from biochemical, functional, histological and molecular parameters. To the best of our knowledge, we report for the first time that activation of ACE2 by DIZE prevents asthma progression by altering AKT, p38, NF-κB and other inflammatory markers. - Highlights: • Diminazene aceturate (DIZE), an ACE2 activator prevents ovalbumin-induced asthma. • DIZE acted by upregulating ACE2, downregulating ACE1, MAPKs, markers of inflammation, apoptosis. • DIZE reduced airway inflammation, fibrosis, right ventricular hypertrophy and

A New Modular Multilevel Converter with Integrated Energy Storage

DEFF Research Database (Denmark)

Trintis, Ionut; Munk-Nielsen, Stig; Teodorescu, Remus

2011-01-01

applications. Furthermore, this solution can interconnect a DC and AC grid with bidirectional power flow, where both of them can receive or generate excess power to the third source integrated in each converter sub-module. This particularity enables the converter usage as a high voltage UPS system......This paper introduces a new modular converter with integrated energy storage based on the cascaded half-bridge modular multilevel converter with common DC bus. It represents a complete modular solution with power electronics and energy storage building blocks, for medium and high voltage...... in the future HVDC meshed grids. Its functionality and flexibility makes the converter independent on the energy storage unit characteristic. The converter concept with its basic functions and control schemes are described and evaluated in this paper....

Operation and Control of a Direct-Driven PMSG-Based Wind Turbine System with an Auxiliary Parallel Grid-Side Converter

Directory of Open Access Journals (Sweden)

Jiawei Chu

2013-07-01

Full Text Available In this paper, based on the similarity, in structure and principle, between a grid-connected converter for a direct-driven permanent magnet synchronous generator (D-PMSG and an active power filter (APF, a new D-PMSG-based wind turbine (WT system configuration that includes not only an auxiliary converter in parallel with the grid-side converter, but also a coordinated control strategy, is proposed to enhance the low voltage ride through (LVRT capability and improve power quality. During normal operation, the main grid-side converter maintains the DC-link voltage constant, whereas the auxiliary grid-side converter functions as an APF with harmonic suppression and reactive power compensation to improve the power quality. During grid faults, a hierarchical coordinated control scheme for the generator-side converter, main grid-side converter and auxiliary grid-side converter, depending on the grid voltage sags, is presented to enhance the LVRT capability of the direct-driven PMSG WT. The feasibility and the effectiveness of the proposed system’s topology and hierarchical coordinated control strategy were verified using MATLAB/Simulink simulations.

Characterization of a fast to thermal neutron spectrum converter on PROSPERO reactor

Energy Technology Data Exchange (ETDEWEB)

Jacquet, X.; Authier, N.; Casoli, P.; Combacon, S. [CEA, Valduc Center, 21120 Is sur Tille (France); Calzavarra, Y. [ILL, Institut Laue Langevin, 38000 Grenoble (France)

2009-07-01

The PROSPERO reactor is located at CEA Valduc Center in France. The reactor is composed of an internal core made of High Enriched Uranium metal alloy surrounded by a reflector of depleted uranium. The reactor is used as a fast neutron spectrum source and is operated in delayed critical state with a continuous and steady power for several hours, which can vary from 3 mW to 3 kW, which is the nominal power. The flux at nominal power varies from 5.10{sup +10} n.cm{sup -2}/s at the reflector surface to 10{sup +7} n.cm{sup -2}/s at 5 meters from reactor axis. It has been decided to build a neutron energy converter allowing the production of a neutron thermal spectrum. As the core produces fast neutrons spectrum, we built a hollow cubic box of 50 cm x 50 cm x 50 cm with 10-cm-thick polyethylene bricks and placed one meter away from central reactor axis to moderate as much as possible neutrons to lower energies (E<0.6 eV). Analysis of the moderated flux inside the converter was performed using different activation foils such as indium or gold. We have developed a model of the experiment in the Monte Carlo neutron transport code TRIPOLI-4. A non-analogous transport calculation scheme was necessary to reproduce properly the experimental activities. The results of the calculated activations are within 4% of the experimental measurements given with 10% uncertainty (2 sigma). We show that the converter realizes thermalization of 80 % of the PROSPERO reactor fast neutrons below the cadmium threshold of 0.6 eV. Epithermal neutrons represent 15% of the spectrum and only 5% are in the fast neutron range above 1 MeV. The total flux at the center of the converter is 1.4 10{sup +9} n.cm{sup -2}/s at 3000 W

Controller for a wave energy converter

Science.gov (United States)

Wilson, David G.; Bull, Diana L.; Robinett, III, Rush D.

2015-09-22

A wave energy converter (WEC) is described, the WEC including a power take off (PTO) that converts relative motion of bodies of the WEC into electrical energy. A controller controls operation of the PTO, causing the PTO to act as a motor to widen a wave frequency spectrum that is usable to generate electrical energy.

Distance relay performance in future converter dominated power systems

DEFF Research Database (Denmark)

Sarkar, Moumita; Jia, Jundi; Yang, Guangya

2017-01-01

Increasing penetration of converter-based generations in power system has led to new system challenges. Short circuit power response from converter-based generations is different from that of traditional synchronous generators. Power electronic converters can be designed for over-current only up ...... of converter controls on fault current response of converter-based generations is also investigated. Index Terms—Converter control, distance relays, power system protection, system modelling....... to 1.1-1.25 times of its nominal value. Low availability of short circuit power can cause many challenges such as misoperation of distance relays. The aim of this paper is to investigate the effect of converter dominated systems on performance of distance relays. Backup functionality of the distance...... relay is major concern as miscoordination of backup relays in case of cascading faults can lead to severe stress in system, which can develop into blackout. In this paper, response of relays in traditional system is compared with response of relays in low short-circuit-current power systems. Impact...

Converter applications and their influence on large electrical machines

CERN Document Server

Drubel, Oliver

2013-01-01

Converter driven applications are applied in more and more processes. Almost any installed wind-farm, ship drives, steel mills, several boiler feed water pumps, extruder and many other applications operate much more efficient and economic in case of variable speed solutions. The boundary conditions for a motor or generator will change, if it is supplied by a converter. An electrical machine, which is operated by a converter, can no longer be regarded as an independent component, but is embedded in a system consisting of converter and machine. This book gives an overview of existing converter designs for large electrical machines. Methods for the appropriate calculation of machine phenomena, which are implied by converters are derived in the power range above 500kVA. It is shown how due to the converter inherent higher voltage harmonics and pulse frequencies special phenomena are caused inside the machine which can be the reason for malfunction. It is demonstrated that additional losses create additional tempe...

Bi-directional power control system for voltage converter

Science.gov (United States)