WorldWideScience

Sample records for voltage clamp experiment

  1. Application of active electrode compensation to perform continuous voltage-clamp recordings with sharp microelectrodes.

    Science.gov (United States)

    Gómez-González, J F; Destexhe, A; Bal, T

    2014-10-01

    Electrophysiological recordings of single neurons in brain tissues are very common in neuroscience. Glass microelectrodes filled with an electrolyte are used to impale the cell membrane in order to record the membrane potential or to inject current. Their high resistance induces a high voltage drop when passing current and it is essential to correct the voltage measurements. In particular, for voltage clamping, the traditional alternatives are two-electrode voltage-clamp technique or discontinuous single electrode voltage-clamp (dSEVC). Nevertheless, it is generally difficult to impale two electrodes in a same neuron and the switching frequency is limited to low frequencies in the case of dSEVC. We present a novel fully computer-implemented alternative to perform continuous voltage-clamp recordings with a single sharp-electrode. To reach such voltage-clamp recordings, we combine an active electrode compensation algorithm (AEC) with a digital controller (AECVC). We applied two types of control-systems: a linear controller (proportional plus integrative controller) and a model-based controller (optimal control). We compared the performance of the two methods to dSEVC using a dynamic model cell and experiments in brain slices. The AECVC method provides an entirely digital method to perform continuous recording and smooth switching between voltage-clamp, current clamp or dynamic-clamp configurations without introducing artifacts.

  2. Equivalent circuit of frog atrial tissue as determined by voltage clamp-unclamp experiments.

    Science.gov (United States)

    Tarr, M; Trank, J

    1971-11-01

    The equivalent circuit that has been used in the analysis of nerve voltage-clamp data is that of the membrane capacity in parallel with the membrane resistance. Voltage-clamp experiments on frog atrial tissue indicate that this circuit will not suffice for this cardiac tissue. The change in membrane current associated with a step change in membrane potential does not show a rapid spike of capacitive current as would be expected for the simple parallel resistance-capacitance network. Rather, there is a step change in current followed by an exponential decay in current with a time constant of about 1 msec. This relatively slow capacitive charging current suggests that there is a resistance in series with the membrane capacity. A possible equivalent circuit is that of a series resistance external to the parallel resistance-capacitance network of the cell membranes. Another possible circuit assumes that the series resistance is an integral part of the cell membrane. The data presented in this paper demonstrate that the equivalent circuit of a bundle of frog atrial muscle is that of an external resistance in series with the cell membranes.

  3. Artifactual voltage response recorded from hair cells with patch-clamp amplifiers.

    Science.gov (United States)

    Masetto, S; Weng, T; Valli, P; Correia, M J

    1999-06-23

    Patch-clamp amplifiers (PCAs) are commonly used to characterize voltage- and current-clamp responses in the same cell. However, the cell membrane voltage response can be severely distorted by PCAs working in the current-clamp mode. Here we compare the voltage response of pigeon semicircular canal hair cells in situ, recorded with two different PCAs, and with a classic microelectrode bridge amplifier (BA). We found that the voltage response of hair cells recorded with PCAs differed significantly from that recorded with the BA. The true hair cell membrane voltage response to positive current steps was characterized by a strongly damped oscillation, whose frequency and duration depended on hair cell location in the sensory crista ampullaris.

  4. Voltage Balancing Control of Diode-Clamped Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    ŞCHIOP Adrian

    2013-10-01

    Full Text Available In this paper is developed a control scheme for mono-phase diode clamped inverter to achieve balancing voltages on inverter capacitors. First, it develops a control scheme without taking into account the need to balance voltage on two capacitors. It examines the effects on the output voltage inverter, and then it realizes two control schemes that will balance the voltages. The simulations of control schemes were performed in OrCAD Pspice.

  5. Common voltage eliminating of SVM diode clamping three-level inverter connected to grid

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Zhu, Jieqiong

    2011-01-01

    A novel method of common voltage eliminating is put forward for SVM diode clamping three-level inverter connected to grid by calculation of common voltage of its various switching states. PLECS is used to model this three-level inverter connected to grid and good results are obtained. First...... analysis of common mode voltage for switching states of diode clamping 3-level inverter is given in detail. Second the common mode voltage eliminating control strategy of SVM is described for diode clamping three-level inverter. Third, PLECS is briefly introduced. Fourth, the modeling of diode clamping...... three-level inverter is presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS is a very powerful tool to real power circuits modeling. They have also verified that proposed common mode voltage eliminating control strategy of SVM is feasible...

  6. Suppression of Spiral Waves by Voltage Clamp Techniques in a Conductance-Based Cardiac Tissue Model

    International Nuclear Information System (INIS)

    Lian-Chun, Yu; Guo-Yong, Zhang; Yong, Chen; Jun, Ma

    2008-01-01

    A new control method is proposed to control the spatio-temporal dynamics in excitable media, which is described by the Morris–Lecar cells model. It is confirmed that successful suppression of spiral waves can be obtained by spatially clamping the membrane voltage of the excitable cells. The low voltage clamping induces breakup of spiral waves and the fragments are soon absorbed by low voltage obstacles, whereas the high voltage clamping generates travel waves that annihilate spiral waves through collision with them. However, each method has its shortcomings. Furthermore, a two-step method that combines both low and high voltage clamp techniques is then presented as a possible way of out this predicament. (cross-disciplinary physics and related areas of science and technology)

  7. An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers

    International Nuclear Information System (INIS)

    Li, Zhen-hua; Li, Hong-bin; Zhang, Zhi

    2013-01-01

    Electronic transformers are widely used in power systems because of their wide bandwidth and good transient performance. However, as an emerging technology, the failure rate of electronic transformers is higher than that of traditional transformers. As a result, the calibration period needs to be shortened. Traditional calibration methods require the power of transmission line be cut off, which results in complicated operation and power off loss. This paper proposes an online calibration system which can calibrate electronic current transformers without power off. In this work, the high accuracy standard current transformer and online operation method are the key techniques. Based on the clamp-shape iron-core coil and clamp-shape air-core coil, a combined clamp-shape coil is designed as the standard current transformer. By analyzing the output characteristics of the two coils, the combined clamp-shape coil can achieve verification of the accuracy. So the accuracy of the online calibration system can be guaranteed. Moreover, by employing the earth potential working method and using two insulating rods to connect the combined clamp-shape coil to the high voltage bus, the operation becomes simple and safe. Tests in China National Center for High Voltage Measurement and field experiments show that the proposed system has a high accuracy of up to 0.05 class

  8. An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers.

    Science.gov (United States)

    Li, Zhen-hua; Li, Hong-bin; Zhang, Zhi

    2013-07-01

    Electronic transformers are widely used in power systems because of their wide bandwidth and good transient performance. However, as an emerging technology, the failure rate of electronic transformers is higher than that of traditional transformers. As a result, the calibration period needs to be shortened. Traditional calibration methods require the power of transmission line be cut off, which results in complicated operation and power off loss. This paper proposes an online calibration system which can calibrate electronic current transformers without power off. In this work, the high accuracy standard current transformer and online operation method are the key techniques. Based on the clamp-shape iron-core coil and clamp-shape air-core coil, a combined clamp-shape coil is designed as the standard current transformer. By analyzing the output characteristics of the two coils, the combined clamp-shape coil can achieve verification of the accuracy. So the accuracy of the online calibration system can be guaranteed. Moreover, by employing the earth potential working method and using two insulating rods to connect the combined clamp-shape coil to the high voltage bus, the operation becomes simple and safe. Tests in China National Center for High Voltage Measurement and field experiments show that the proposed system has a high accuracy of up to 0.05 class.

  9. Simple hardware implementation of voltage balancing in capacitor-clamped inverter

    Czech Academy of Sciences Publication Activity Database

    Kokeš, Petr; Semerád, Radko

    2009-01-01

    Roč. 54, č. 4 (2009), s. 325-341 ISSN 0001-7043 R&D Projects: GA MPO FT-TA4/077 Institutional research plan: CEZ:AV0Z20570509 Keywords : capacitor -clamped multilevel inverter * flying capacitor voltage balancing * pulse width modulation (PWM) Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  10. The Anion Paradox in Sodium Taste Reception: Resolution by Voltage-Clamp Studies

    Science.gov (United States)

    Ye, Qing; Heck, Gerard L.; Desimone, John A.

    1991-11-01

    Sodium salts are potent taste stimuli, but their effectiveness is markedly dependent on the anion, with chloride yielding the greatest response. The cellular mechanisms that mediate this phenomenon are not known. This "anion paradox" has been resolved by considering the field potential that is generated by restricted electrodiffusion of the anion through paracellular shunts between taste-bud cells. Neural responses to sodium chloride, sodium acetate, and sodium gluconate were studied while the field potential was voltage-clamped. Clamping at electronegative values eliminated the anion effect, whereas clamping at electropositive potentials exaggerated it. Thus, field potentials across the lingual epithelium modulate taste reception, indicating that the functional unit of taste reception includes the taste cell and its paracellular microenvironment.

  11. 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...

  12. Isolated PWM DC-AC SICAM with an active capacitive voltage clamp[Pulse Density Modulated; Pulse Width Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2004-03-15

    In this report an isolated PWM DC-AC SICAM with an active capacitive voltage clamp is presented. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitors and possibly with an EMC filter on the mains entrance. Isolation from the AC mains is achieved using a high frequency (HF) transformer, whose voltages are not audio-modulated. The latter simplifies the design and is expected to have many advantages over the approach where the transformer voltages are modulated in regards to the audio signal reference. Input stage is built as a DC-AC inverter (push-pull, half-bridge or a full-bridge) and operated with 50% duty cycle, with all the challenges to avoid transformer saturation and obtain symmetrical operation. On the secondary side the output section is implemented as rectifier+inverter AC-AC stage, i.e. a true bidirectional bridge, which operation is aimed towards amplification of the audio signal. In order to solve the problem with the commutation of the load current, a dead time between the incoming and outgoing bidirectional switch is implemented, while a capacitive voltage clamp is used to keep the induced overvoltage to reasonable levels. The energy stored in the clamping capacitor is not wasted as in the dissipative clamps, but is rather transferred back to the primary side for further processing using an auxiliary isolated single-switch converter, i.e. an active clamping technique is used. (au)

  13. Investigating ion channel conformational changes using voltage clamp fluorometry.

    Science.gov (United States)

    Talwar, Sahil; Lynch, Joseph W

    2015-11-01

    Ion channels are membrane proteins whose functions are governed by conformational changes. The widespread distribution of ion channels, coupled with their involvement in most physiological and pathological processes and their importance as therapeutic targets, renders the elucidation of these conformational mechanisms highly compelling from a drug discovery perspective. Thanks to recent advances in structural biology techniques, we now have high-resolution static molecular structures for members of the major ion channel families. However, major questions remain to be resolved about the conformational states that ion channels adopt during activation, drug modulation and desensitization. Patch-clamp electrophysiology has long been used to define ion channel conformational states based on functional criteria. It achieves this by monitoring conformational changes at the channel gate and cannot detect conformational changes occurring in regions distant from the gate. Voltage clamp fluorometry involves labelling cysteines introduced into domains of interest with environmentally sensitive fluorophores and inferring structural rearrangements from voltage or ligand-induced fluorescence changes. Ion channel currents are monitored simultaneously to verify the conformational status. By defining real time conformational changes in domains distant from the gate, this technique provides unexpected new insights into ion channel structure and function. This review aims to summarise the methodology and highlight recent innovative applications of this powerful technique. This article is part of the Special Issue entitled 'Fluorescent Tools in Neuropharmacology'. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Voltage clamp methods for the study of membrane currents and SR Ca2+ release in adult skeletal muscle fibres

    Science.gov (United States)

    Hernández-Ochoa, Erick O.; Schneider, Martin F.

    2012-01-01

    Skeletal muscle excitation-contraction (E-C)1 coupling is a process composed of multiple sequential stages, by which an action potential triggers sarcoplasmic reticulum (SR)2 Ca2+ release and subsequent contractile activation. The various steps in the E-C coupling process in skeletal muscle can be studied using different techniques. The simultaneous recordings of sarcolemmal electrical signals and the accompanying elevation in myoplasmic Ca2+, due to depolarization-initiated SR Ca2+ release in skeletal muscle fibres, have been useful to obtain a better understanding of muscle function. In studying the origin and mechanism of voltage dependency of E-C coupling a variety of different techniques have been used to control the voltage in adult skeletal fibres. Pioneering work in muscles isolated from amphibians or crustaceans used microelectrodes or ‘high resistance gap’ techniques to manipulate the voltage in the muscle fibres. The development of the patch clamp technique and its variant, the whole-cell clamp configuration that facilitates the manipulation of the intracellular environment, allowed the use of the voltage clamp techniques in different cell types, including skeletal muscle fibres. The aim of this article is to present an historical perspective of the voltage clamp methods used to study skeletal muscle E-C coupling as well as to describe the current status of using the whole-cell patch clamp technique in studies in which the electrical and Ca2+ signalling properties of mouse skeletal muscle membranes are being investigated. PMID:22306655

  15. A low-voltage sense amplifier with two-stage operational amplifier clamping for flash memory

    Science.gov (United States)

    Guo, Jiarong

    2017-04-01

    A low-voltage sense amplifier with reference current generator utilizing two-stage operational amplifier clamp structure for flash memory is presented in this paper, capable of operating with minimum supply voltage at 1 V. A new reference current generation circuit composed of a reference cell and a two-stage operational amplifier clamping the drain pole of the reference cell is used to generate the reference current, which avoids the threshold limitation caused by current mirror transistor in the traditional sense amplifier. A novel reference voltage generation circuit using dummy bit-line structure without pull-down current is also adopted, which not only improves the sense window enhancing read precision but also saves power consumption. The sense amplifier was implemented in a flash realized in 90 nm flash technology. Experimental results show the access time is 14.7 ns with power supply of 1.2 V and slow corner at 125 °C. Project supported by the National Natural Science Fundation of China (No. 61376028).

  16. Quantitative analysis of dual whole-cell voltage-clamp determination of gap junctional conductance

    NARCIS (Netherlands)

    van Rijen, H. V.; Wilders, R.; van Ginneken, A. C.; Jongsma, H. J.

    1998-01-01

    The dual whole-cell voltage-clamp technique is used widely for determination of kinetics and conductance of gap junctions. The use of this technique may, however, occasion to considerable errors. We have analysed the errors in steady state junctional conductance measurements under different

  17. Limitations of the dual voltage clamp method in assaying conductance and kinetics of gap junction channels

    NARCIS (Netherlands)

    Wilders, R.; Jongsma, H. J.

    1992-01-01

    The electrical properties of gap junctions in cell pairs are usually studied by means of the dual voltage clamp method. The voltage across the junctional channels, however, cannot be controlled adequately due to an artificial resistance and a natural resistance, both connected in series with the gap

  18. Potassium Chloride Versus Voltage Clamp Contractures in Ventricular Muscle

    Science.gov (United States)

    Morad, M.; Reeck, S.; Rao, M.

    1981-01-01

    In frog ventricle, developed tension was markedly larger in response to depolarization caused by a voltage clamp step than to depolarization induced by high concentrations of potassium chloride. Measurement of extracellular potassium activity at the surface and at the depth of muscle during the development of contractures showed that the diffusion of potassium is much slower than the spread of depolarization through the cross section of muscle. These two observations suggest that competition between the depolarizing and the negative inotropic effects of an increase in the extracellular potassium ion concentration may determine the time course and magnitude of contractile tension in heart muscle.

  19. Accurate measurement of junctional conductance between electrically coupled cells with dual whole-cell voltage-clamp under conditions of high series resistance.

    Science.gov (United States)

    Hartveit, Espen; Veruki, Margaret Lin

    2010-03-15

    Accurate measurement of the junctional conductance (G(j)) between electrically coupled cells can provide important information about the functional properties of coupling. With the development of tight-seal, whole-cell recording, it became possible to use dual, single-electrode voltage-clamp recording from pairs of small cells to measure G(j). Experiments that require reduced perturbation of the intracellular environment can be performed with high-resistance pipettes or the perforated-patch technique, but an accompanying increase in series resistance (R(s)) compromises voltage-clamp control and reduces the accuracy of G(j) measurements. Here, we present a detailed analysis of methodologies available for accurate determination of steady-state G(j) and related parameters under conditions of high R(s), using continuous or discontinuous single-electrode voltage-clamp (CSEVC or DSEVC) amplifiers to quantify the parameters of different equivalent electrical circuit model cells. Both types of amplifiers can provide accurate measurements of G(j), with errors less than 5% for a wide range of R(s) and G(j) values. However, CSEVC amplifiers need to be combined with R(s)-compensation or mathematical correction for the effects of nonzero R(s) and finite membrane resistance (R(m)). R(s)-compensation is difficult for higher values of R(s) and leads to instability that can damage the recorded cells. Mathematical correction for R(s) and R(m) yields highly accurate results, but depends on accurate estimates of R(s) throughout an experiment. DSEVC amplifiers display very accurate measurements over a larger range of R(s) values than CSEVC amplifiers and have the advantage that knowledge of R(s) is unnecessary, suggesting that they are preferable for long-duration experiments and/or recordings with high R(s). Copyright (c) 2009 Elsevier B.V. All rights reserved.

  20. Overmodulation of n-level three-leg DC-AC diode-clamped converters with comprehensive capacitor voltage balance

    DEFF Research Database (Denmark)

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

    2013-01-01

    This paper presents a novel PWM strategy for nlevel three-leg semiconductor-clamped dc-ac converters in the overmodulation region, with dc-link capacitor voltage balance in every switching cycle. The strategy is based on the virtual-vector concept. Suitable reference vector trajectories are selec......This paper presents a novel PWM strategy for nlevel three-leg semiconductor-clamped dc-ac converters in the overmodulation region, with dc-link capacitor voltage balance in every switching cycle. The strategy is based on the virtual-vector concept. Suitable reference vector trajectories...

  1. Characterization of heterologously expressed transporter genes by patch- and voltage-clamp methods: Application to cyclic nucleotide-dependent responses

    KAUST Repository

    Lemtiri-Chlieh, Fouad

    2013-09-03

    The application of patch- and voltage-clamp methods to study ion transport can be limited by many hurdles: the size of the cells to be patched and/or stabbed, the subcellular localization of the molecule of interest, and its density of expression that could be too low even in their own native environment. Functional expression of genes using recombinant DNA technology not only overcomes those hurdles but also affords additional and elegant investigations such as single-point mutation studies and subunit associations/regulations. In this chapter, we give a step-by-step description of two electrophysiological methods, patch clamp and two-electrode voltage clamp (TEVC), that are routinely used in combination with heterologous gene expression to assist researchers interested in the identification and characterization of ion transporters. We describe how to (1) obtain and maintain the cells suitable for the use with each of the above-mentioned methods (i.e., HEK-293 cells and yeast spheroplasts to use with the patch-clamp methodology and Xenopus laevis oocytes with TEVC), (2) transfect/inject them with the gene of interest, and (3) record ion transport activities. © Springer Science+Business Media New York 2013.

  2. Characterization of heterologously expressed transporter genes by patch- and voltage-clamp methods: Application to cyclic nucleotide-dependent responses

    KAUST Repository

    Lemtiri-Chlieh, Fouad; Ali, Rashid Ayesha

    2013-01-01

    The application of patch- and voltage-clamp methods to study ion transport can be limited by many hurdles: the size of the cells to be patched and/or stabbed, the subcellular localization of the molecule of interest, and its density of expression that could be too low even in their own native environment. Functional expression of genes using recombinant DNA technology not only overcomes those hurdles but also affords additional and elegant investigations such as single-point mutation studies and subunit associations/regulations. In this chapter, we give a step-by-step description of two electrophysiological methods, patch clamp and two-electrode voltage clamp (TEVC), that are routinely used in combination with heterologous gene expression to assist researchers interested in the identification and characterization of ion transporters. We describe how to (1) obtain and maintain the cells suitable for the use with each of the above-mentioned methods (i.e., HEK-293 cells and yeast spheroplasts to use with the patch-clamp methodology and Xenopus laevis oocytes with TEVC), (2) transfect/inject them with the gene of interest, and (3) record ion transport activities. © Springer Science+Business Media New York 2013.

  3. New Modulation Strategy to Balance the Neutral-Point Voltage for Three-Level Neutral-Clamped Inverter Systems

    DEFF Research Database (Denmark)

    Choi, Uimin; Lee, June-Seok; Lee, Kyo-Beum

    2014-01-01

    This paper proposes a new modulation strategy that balances the neutral-point voltage for three-level neutral-clamped inverter systems. The proposed modulation replaces the P-type or N-type small switching states with other switching states that do not affect the neutral-point voltage. The zero...... and medium switching states are employed to help the neutral-point voltage balancing. This method little bit increases the switching events and output total harmonic distortion. However, this method has a strong balancing ability at all regions. Further, it is very simple to implement in both space vector...

  4. Voltage-Sharing Converter to Supply Single-Phase Asymmetrical Four-Level Diode-Clamped Inverter With High Power Factor Loads

    DEFF Research Database (Denmark)

    Boora, Arash A.; Nami, Alireza; Zare, Firuz

    2010-01-01

    The output voltage quality of some of the single-phase multilevel inverters can be improved when their dc-link voltages are regulated asymmetrically. Symmetrical and asymmetrical multilevel diode-clamped inverters have the problem of dc-link capacitor voltage balancing, especially when power factor...... that the proposed combination of introduced multioutput dc–dc converter and single-phase ADCI is a good candidate for power conversion in residential photovoltaic (PV) utilization....

  5. Dual patch voltage clamp study of low membrane resistance astrocytes in situ.

    Science.gov (United States)

    Ma, Baofeng; Xu, Guangjin; Wang, Wei; Enyeart, John J; Zhou, Min

    2014-03-17

    Whole-cell patch clamp recording has been successfully used in identifying the voltage-dependent gating and conductance properties of ion channels in a variety of cells. However, this powerful technique is of limited value in studying low membrane resistance cells, such as astrocytes in situ, because of the inability to control or accurately measure the real amplitude of command voltages. To facilitate the study of ionic conductances of astrocytes, we have developed a dual patch recording method which permits membrane current and membrane potential to be simultaneously recorded from astrocytes in spite of their extraordinarily low membrane resistance. The utility of this technique is demonstrated by measuring the voltage-dependent activation of the inwardly rectifying K+ current abundantly expressed in astrocytes and multiple ionic events associated with astrocytic GABAA receptor activation. This protocol can be performed routinely in the study of astrocytes. This method will be valuable for identifying and characterizing the individual ion channels that orchestrate the electrical activity of low membrane resistance cells.

  6. Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-07-01

    This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify design, increase efficiency and integration level, reduce product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented. (au)

  7. Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify the design, increase...... efficiency, reduce the product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented....

  8. Limitations of the dual voltage clamp method in assaying conductance and kinetics of gap junction channels

    OpenAIRE

    Wilders, R.; Jongsma, H.J.

    1992-01-01

    The electrical properties of gap junctions in cell pairs are usually studied by means of the dual voltage clamp method. The voltage across the junctional channels, however, cannot be controlled adequately due to an artificial resistance and a natural resistance, both connected in series with the gap junction. The access resistances to the cell interior of the recording pipettes make up the artificial resistance. The natural resistance consists of the cytoplasmic access resistances to the tigh...

  9. Finite element analysis on factors influencing the clamping force in an electrostatic chuck

    International Nuclear Information System (INIS)

    Wang Xingkuo; Yang Yiyong; Cheng Jia; Wang Kesheng; Sun Yuchun; Cao Minglu; Ji Linhong

    2014-01-01

    As one of the core components of IC manufacturing equipment, the electrostatic chuck (ESC) has been widely applied in semiconductor processing such as etching, PVD and CVD. The clamping force of the ESC is one of the most important technical indicators. A multi-physics simulation software COMSOL is used to analyze the factors influencing the clamping force. The curves between the clamping force and the main parameters such as DC voltage, electrode thickness, electrode radius, dielectric thickness and helium gap are obtained. Moreover, the effects of these factors on the clamping force are investigated by means of orthogonal experiments. The results show that the factors can be ranked in order of voltage, electrode radius, helium gap and dielectric thickness according to their importance, which may offer certain reference for the design of ESCs. (semiconductor devices)

  10. IMPORTANT: Fluke is recalling Digital Clamp Meters

    CERN Multimedia

    2013-01-01

    Fluke is voluntarily recalling four models of Digital Clamp Meters: Fluke 373, 374, 375 and 376. If you own one of these clamp meters, please stop using it and send it back to Fluke for repair even if you have not experienced problems.   Description of the problem: "The printed circuit assembly may not be properly fastened to the test lead input jack. This may result in inaccurate voltage readings, including a low or no-voltage reading on a circuit energised with a hazardous voltage, presenting a shock, electrocution or thermal burn hazard." To determine if your clamp meter is affected by this recall notice, and for more information, click here.

  11. Transformer-based asymmetrical embedded Z-source neutral point clamped inverters with continuous input current and enhanced voltage boost capability

    DEFF Research Database (Denmark)

    Mo, W.; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    Z-source Neutral Point Clamped (NPC) inverters were introduced to integrate both the advantages of Z-source inverters and NPC inverters. However, traditional Z-source inverters suffer from high voltage stress and chopping input current. This paper proposes six types transformer-based impedance-so......-source NPC inverters which have enhanced voltage boost capability and continuous input current by utilizing of transformer and embedded dc source configuration. Experimental results are presented to verify the theory validation....

  12. A DC-Link Voltage Self-Balance Method for a Diode-Clamped Modular Multilevel Converter With Minimum Number of Voltage Sensors

    DEFF Research Database (Denmark)

    Gao, Congzhe; Jiang, Xinjian; Li, Yongdong

    2013-01-01

    Voltage balance issue of dc-link capacitors is very important for applications of a cascade multilevel converter or a modular multilevel converter. In this paper, a novel diode-clamped modular multilevel converter (DCM2C) topology is proposed and a power feedback control method is developed...... used traditional method; therefore, the system performance improvement and cost reduction are expected. Based on the proposed DCM2C, a novel N +1-level cascade multilevel topology is proposed for a cascade active power filter (CS-APF). The simulation and experimental results from the CS-APF have...

  13. Contamination of current-clamp measurement of neuron capacitance by voltage-dependent phenomena

    Science.gov (United States)

    White, William E.

    2013-01-01

    Measuring neuron capacitance is important for morphological description, conductance characterization, and neuron modeling. One method to estimate capacitance is to inject current pulses into a neuron and fit the resulting changes in membrane potential with multiple exponentials; if the neuron is purely passive, the amplitude and time constant of the slowest exponential give neuron capacitance (Major G, Evans JD, Jack JJ. Biophys J 65: 423–449, 1993). Golowasch et al. (Golowasch J, Thomas G, Taylor AL, Patel A, Pineda A, Khalil C, Nadim F. J Neurophysiol 102: 2161–2175, 2009) have shown that this is the best method for measuring the capacitance of nonisopotential (i.e., most) neurons. However, prior work has not tested for, or examined how much error would be introduced by, slow voltage-dependent phenomena possibly present at the membrane potentials typically used in such work. We investigated this issue in lobster (Panulirus interruptus) stomatogastric neurons by performing current clamp-based capacitance measurements at multiple membrane potentials. A slow, voltage-dependent phenomenon consistent with residual voltage-dependent conductances was present at all tested membrane potentials (−95 to −35 mV). This phenomenon was the slowest component of the neuron's voltage response, and failure to recognize and exclude it would lead to capacitance overestimates of several hundredfold. Most methods of estimating capacitance depend on the absence of voltage-dependent phenomena. Our demonstration that such phenomena make nonnegligible contributions to neuron responses even at well-hyperpolarized membrane potentials highlights the critical importance of checking for such phenomena in all work measuring neuron capacitance. We show here how to identify such phenomena and minimize their contaminating influence. PMID:23576698

  14. Excitation contraction uncoupling by high intracellular [Ca2+] in frog skeletal muscle: a voltage clamp study.

    Science.gov (United States)

    Olivera, J Fernando; Pizarro, Gonzalo

    2016-10-01

    Raising the intracellular [Ca 2+ ] ([Ca 2+ ] i ) was previously found to produce uncoupling between the electrical depolarization of the transverse tubules and contraction in skinned muscle fibers. Here we study the effect of elevated [Ca 2+ ] i in voltage clamped cut fibers of frog skeletal muscle to establish how the charge movement, a measure of the activation of the dihydropyridine receptors (DHPR)-voltage sensors, and Ca 2+ release, a consequence of the opening of the ryanodine receptor (RyR)-release channels, were affected. [Ca 2+ ] i was raised by various procedures (pharmacological release from the sarcoplasmic reticulum, application of high [Ca 2+ ] i intracellular solution, permeabilization of the plasma membrane by a Ca 2+ ionophore) all of which produced impairment of excitation-contraction coupling. The charge movement was reduced from 20.2 ± 1.24 to 9.9 ± 0.94 nC/μF meanwhile the Ca 2+ release flux was reduced from 13.5 + 0.7 to 2.2 ± 0.3 μM/ms (n = 33). This suggests that a significant fraction of the DHPRs that remained functional, could not activate RyRs, and were therefore presumably disconnected. These results are broadly consistent with the original reports in skinned fibers. Uncoupling was prevented by the addition to the intracellular solution of the protease inhibitor leupeptin. In approximately 40 % of the uncoupled cells we observed that the [Ca 2+ ] i transient continued to rise after the voltage clamp pulse was turned off. This loss of control by membrane voltage suggests that the uncoupled release channels might have another mechanism of activation, likely by Ca 2+ .

  15. 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.

  16. Closed-form solution for static pull-in voltage of electrostatically actuated clamped-clamped micro/nano beams under the effect of fringing field and van der Waals force

    Science.gov (United States)

    Bhojawala, V. M.; Vakharia, D. P.

    2017-12-01

    This investigation provides an accurate prediction of static pull-in voltage for clamped-clamped micro/nano beams based on distributed model. The Euler-Bernoulli beam theory is used adapting geometric non-linearity of beam, internal (residual) stress, van der Waals force, distributed electrostatic force and fringing field effects for deriving governing differential equation. The Galerkin discretisation method is used to make reduced-order model of the governing differential equation. A regime plot is presented in the current work for determining the number of modes required in reduced-order model to obtain completely converged pull-in voltage for micro/nano beams. A closed-form relation is developed based on the relationship obtained from curve fitting of pull-in instability plots and subsequent non-linear regression for the proposed relation. The output of regression analysis provides Chi-square (χ 2) tolerance value equals to 1  ×  10-9, adjusted R-square value equals to 0.999 29 and P-value equals to zero, these statistical parameters indicate the convergence of non-linear fit, accuracy of fitted data and significance of the proposed model respectively. The closed-form equation is validated using available data of experimental and numerical results. The relative maximum error of 4.08% in comparison to several available experimental and numerical data proves the reliability of the proposed closed-form equation.

  17. A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter

    DEFF Research Database (Denmark)

    Qin, Zian; Pang, Ying; Wang, Huai

    2016-01-01

    The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...

  18. Molecular motions that shape the cardiac action potential: Insights from voltage clamp fluorometry.

    Science.gov (United States)

    Zhu, Wandi; Varga, Zoltan; Silva, Jonathan R

    2016-01-01

    Very recently, voltage-clamp fluorometry (VCF) protocols have been developed to observe the membrane proteins responsible for carrying the ventricular ionic currents that form the action potential (AP), including those carried by the cardiac Na(+) channel, NaV1.5, the L-type Ca(2+) channel, CaV1.2, the Na(+)/K(+) ATPase, and the rapid and slow components of the delayed rectifier, KV11.1 and KV7.1. This development is significant, because VCF enables simultaneous observation of ionic current kinetics with conformational changes occurring within specific channel domains. The ability gained from VCF, to connect nanoscale molecular movement to ion channel function has revealed how the voltage-sensing domains (VSDs) control ion flux through channel pores, mechanisms of post-translational regulation and the molecular pathology of inherited mutations. In the future, we expect that this data will be of great use for the creation of multi-scale computational AP models that explicitly represent ion channel conformations, connecting molecular, cell and tissue electrophysiology. Here, we review the VCF protocol, recent results, and discuss potential future developments, including potential use of these experimental findings to create novel computational models. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Balance control strategy of two-amplitude actively clamped resonant DC-Link inverter clamping voltage%双幅有源箝位谐振直流环节逆变器箝位电压平衡控制策略

    Institute of Scientific and Technical Information of China (English)

    陈沁野; 张德华; 侯尧杰

    2012-01-01

    Aiming at the big loss of the traditional clamping voltage balance control strategies, in two-amplitude actively clamped resonant DC-LINK inverter, the work process of DC link was analyzed. In order to keep the clamp capacitor voltage balance the value set in DC-link work, no short-circuit control was proposed.The DC-link of inverter was calculated by Mathcad. The loss of two modes of short-circuit control and no short-circuit control were compared.Under the no short-circuit control and voltage ripple is not be greater than twenty percent, the parameters of the clamp capacitor were calculated. The results indicate that, the micro-power ACRDCLI clamping voltage balance use no short-circuit control,that can reduce the loss of the DC link and can use thin-film capacitor as a clamp capacitor to achieve the micro-power ACRDCLI low loss and iong life requirements.%针对微型功率双幅有源箝位谐振直流环节逆变器在正常工作过程中,传统箝位电压平衡母线短路控制策略带来损耗大的问题,开展了直流环节工作过程的分析,针对直流环节正常工作的情况下,箝位电容电压必须能平衡在设定值,提出了箝位电压平衡母线无短路控制策略,根据给出的损耗估算方法,通过Mathcad计算,对比了母线短路控制和无短路控制两种方式下的损耗,同时计算出了母线无短路控制箝位电容电压纹波不大于20%下的箝位电容参数.研究结果表明:微型功率ACRDCLI箝位电压平衡采用母线无短线控制,不但可以减少双幅有源箝位谐振直流环节逆变器的损耗,并且可以使用薄膜电容作为箝位电容,以达到微型功率ACRDCLI损耗低、寿命长的要求.

  20. Modeling of SVM Diode Clamping Three-Level Inverter Connected to Grid

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Zhu, Jieqiong

    2011-01-01

    PLECS is used to model the diode clamping three-level inverter connected to grid and good results are obtained. First the output voltage SVM is described for diode clamping three-level inverter with loads connected to Y. Then the output voltage SVM of diode clamping three-level inverter is simply...... analyzed with loads connected to △. But it will be further researched in the future. Third, PLECS is briefly introduced. Fourth, the modeling of diode clamping three-level inverter is briefly presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS...... is very powerful tool to real power circuits and it is very easy to simulate them. They have also verified that SVM control strategy is feasible to control the diode clamping three-level inverter....

  1. Analysis and Experiments on Sea Load and Fastened Mechanics on Pipe Clamps

    Directory of Open Access Journals (Sweden)

    Wang Zhuo

    2017-08-01

    Full Text Available When an offshore oil field completed and put into production, new subsea pipelines and the new cable need to be established. Cable protection pipe clamp is used to fix cable protection pipe on the jacket. In order to avoid the problem of traditional steel structure clamp splice, counterpoint, fastening difficulty when installed cable protection pipe under water, reduce the risk and workload of under water, This paper develop a new type of portable connecting riser clamp -“backpack clamp” which solve the riser cable protection pipe difficult underwater installation problem. The main structure of backpack clamp used three valves type structure. The load characteristic of a clamping device was determined by the Morison equation which was a classical theory. Clamp device underwater mechanics analysis model was established. The minimum tension pre-tightening force was determined. The results show that the strength of the base meets the requirements after strength analysis with finite element analysis method, stability and strength experiments, which means the clamp based on resin matrix composite is feasible.

  2. Force-controlled patch clamp of beating cardiac cells.

    Science.gov (United States)

    Ossola, Dario; Amarouch, Mohamed-Yassine; Behr, Pascal; Vörös, János; Abriel, Hugues; Zambelli, Tomaso

    2015-03-11

    From its invention in the 1970s, the patch clamp technique is the gold standard in electrophysiology research and drug screening because it is the only tool enabling accurate investigation of voltage-gated ion channels, which are responsible for action potentials. Because of its key role in drug screening, innovation efforts are being made to reduce its complexity toward more automated systems. While some of these new approaches are being adopted in pharmaceutical companies, conventional patch-clamp remains unmatched in fundamental research due to its versatility. Here, we merged the patch clamp and atomic force microscope (AFM) techniques, thus equipping the patch-clamp with the sensitive AFM force control. This was possible using the FluidFM, a force-controlled nanopipette based on microchanneled AFM cantilevers. First, the compatibility of the system with patch-clamp electronics and its ability to record the activity of voltage-gated ion channels in whole-cell configuration was demonstrated with sodium (NaV1.5) channels. Second, we showed the feasibility of simultaneous recording of membrane current and force development during contraction of isolated cardiomyocytes. Force feedback allowed for a gentle and stable contact between AFM tip and cell membrane enabling serial patch clamping and injection without apparent cell damage.

  3. A Hybrid Cascade Converter Topology With Series-Connected Symmetrical and Asymmetrical Diode-Clamped H-Bridge Cells

    DEFF Research Database (Denmark)

    Nami, Alireza; Zare, Firuz; Ghosh, Arindam

    2011-01-01

    to approach a very low total harmonic distortion of voltage and current, which leads to the possible elimination of the output filter. Regarding the proposed configuration, a new cascade inverter is verified by cascading an asymmetrical diode-clamped inverter, in which 19 levels can be synthesized in output......A novel H-bridge multilevel pulsewidth modulation converter topology based on a series connection of a high-voltage diode-clamped inverter and a low-voltage conventional inverter is proposed in this paper. A dc link voltage arrangement for the new hybrid and asymmetric solution is presented to have...... voltage with the same number of components. To balance the dc link capacitor voltages for the maximum output voltage resolution as well as synthesize asymmetrical dc link combination, a new multi-output boost converter is utilized at the dc link voltage of a seven-level H-bridge diode-clamped inverter...

  4. Three Level Diode Clamped Inverter Fed Induction Motor with Dtc-Svm

    OpenAIRE

    V. Ranjith Kumar

    2013-01-01

    This project presents a three-level diode-clamped inverter feeding an asynchronous motor drive with direct torque control (DTC). The control method is based on DTC operating principles. The stator voltage vector reference is computed from the stator flux and torque errors imposed by the flux and torque controllers. This voltage reference is then generated using a diode-clamped inverter, where each phase of the inverter can be implemented using a dc source, which would be available from fuel c...

  5. The plastic instability of clamped-clamped conical thin-walled pipe reducers

    International Nuclear Information System (INIS)

    Awad, Ibrahim; Saleh, Ch.A.R.; Ragab, A.R.

    2016-01-01

    The analytical study for plastic deformation of clamped–clamped conical reducer pipe under internal pressure does not deduce a closed form expression for the pressure at plastic instability. The presented study employs finite element analysis (FEA) to estimate the internal pressure at instability for conical reducers made of different materials and having different dimensional configurations. Forty dimensional configurations, classified as medium type, and five types of materials have been included in the analysis using ABAQUS package. A correlation expression is derived by nonlinear regression to predict the instability pressure. The proposed expression is verified for other dimensional configurations out of the above used forty models and for other materials. Experiments have been conducted by pressurizing conical clamped-clamped reducers until bursting in order to verify the finite element models. Comparison of instability pressures, strains and deflections at specific points along the conical surface shows satisfactory agreement between analysis and experiments. - Highlights: • This study offers a parametric study of the plastic instability pressure of clamped-clamped conical reducers. • A closed form analytical expression for the instability pressure is derived by using nonlinear regression. • The finite element analysis is validated by conducting bursting tests.

  6. Sinusoidal voltage protocols for rapid characterisation of ion channel kinetics.

    Science.gov (United States)

    Beattie, Kylie A; Hill, Adam P; Bardenet, Rémi; Cui, Yi; Vandenberg, Jamie I; Gavaghan, David J; de Boer, Teun P; Mirams, Gary R

    2018-03-24

    Ion current kinetics are commonly represented by current-voltage relationships, time constant-voltage relationships and subsequently mathematical models fitted to these. These experiments take substantial time, which means they are rarely performed in the same cell. Rather than traditional square-wave voltage clamps, we fitted a model to the current evoked by a novel sum-of-sinusoids voltage clamp that was only 8 s long. Short protocols that can be performed multiple times within a single cell will offer many new opportunities to measure how ion current kinetics are affected by changing conditions. The new model predicts the current under traditional square-wave protocols well, with better predictions of underlying currents than literature models. The current under a novel physiologically relevant series of action potential clamps is predicted extremely well. The short sinusoidal protocols allow a model to be fully fitted to individual cells, allowing us to examine cell-cell variability in current kinetics for the first time. Understanding the roles of ion currents is crucial to predict the action of pharmaceuticals and mutations in different scenarios, and thereby to guide clinical interventions in the heart, brain and other electrophysiological systems. Our ability to predict how ion currents contribute to cellular electrophysiology is in turn critically dependent on our characterisation of ion channel kinetics - the voltage-dependent rates of transition between open, closed and inactivated channel states. We present a new method for rapidly exploring and characterising ion channel kinetics, applying it to the hERG potassium channel as an example, with the aim of generating a quantitatively predictive representation of the ion current. We fitted a mathematical model to currents evoked by a novel 8 second sinusoidal voltage clamp in CHO cells overexpressing hERG1a. The model was then used to predict over 5 minutes of recordings in the same cell in response to

  7. Implementation of a fast 16-Bit dynamic clamp using LabVIEW-RT.

    Science.gov (United States)

    Kullmann, Paul H M; Wheeler, Diek W; Beacom, Joshua; Horn, John P

    2004-01-01

    The dynamic-clamp method provides a powerful electrophysiological tool for creating virtual ionic conductances in living cells and studying their influence on membrane potential. Here we describe G-clamp, a new way to implement a dynamic clamp using the real-time version of the Lab-VIEW programming environment together with a Windows host, an embedded microprocessor that runs a real-time operating system and a multifunction data-acquisition board. The software includes descriptions of a fast voltage-dependent sodium conductance, delayed rectifier, M-type and A-type potassium conductances, and a leak conductance. The system can also read synaptic conductance waveforms from preassembled data files. These virtual conductances can be reliably implemented at speeds < or =43 kHz while simultaneously saving two channels of data with 16-bit precision. G-clamp also includes utilities for measuring current-voltage relations, synaptic strength, and synaptic gain. Taking an approach built on a commercially available software/hardware platform has resulted in a system that is easy to assemble and upgrade. In addition, the graphical programming structure of LabVIEW should make it relatively easy for others to adapt G-clamp for new experimental applications.

  8. Piezoresistive cantilever force-clamp system

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung-Jin; Petzold, Bryan C.; Pruitt, Beth L. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Goodman, Miriam B. [Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305 (United States)

    2011-04-15

    We present a microelectromechanical device-based tool, namely, a force-clamp system that sets or ''clamps'' the scaled force and can apply designed loading profiles (e.g., constant, sinusoidal) of a desired magnitude. The system implements a piezoresistive cantilever as a force sensor and the built-in capacitive sensor of a piezoelectric actuator as a displacement sensor, such that sample indentation depth can be directly calculated from the force and displacement signals. A programmable real-time controller operating at 100 kHz feedback calculates the driving voltage of the actuator. The system has two distinct modes: a force-clamp mode that controls the force applied to a sample and a displacement-clamp mode that controls the moving distance of the actuator. We demonstrate that the system has a large dynamic range (sub-nN up to tens of {mu}N force and nm up to tens of {mu}m displacement) in both air and water, and excellent dynamic response (fast response time, <2 ms and large bandwidth, 1 Hz up to 1 kHz). In addition, the system has been specifically designed to be integrated with other instruments such as a microscope with patch-clamp electronics. We demonstrate the capabilities of the system by using it to calibrate the stiffness and sensitivity of an electrostatic actuator and to measure the mechanics of a living, freely moving Caenorhabditis elegans nematode.

  9. Correlation of open cell-attached and excised patch clamp techniques.

    Science.gov (United States)

    Filipovic, D; Hayslett, J P

    1995-11-01

    The excised patch clamp configuration provides a unique technique for some types of single channel analyses, but maintenance of stable, long-lasting preparations may be confounded by rundown and/or rapid loss of seal. Studies were performed on the amiloride-sensitive Na+ channel, located on the apical surface of A6 cells, to determine whether the nystatin-induced open cell-attached patch could serve as an alternative configuration. Compared to excised inside-out patches, stable preparations were achieved more readily with the open cell-attached patch (9% vs. 56% of attempts). In both preparations, the current voltage (I-V) relation was linear, current amplitudes were equal at opposite equivalent clamped voltages, and Erev was zero in symmetrical Na+ solutions, indicating similar Na+ activities on the cytosolic and external surfaces of the patch. Moreover, there was no evidence that nystatin altered channel activity in the patch because slope conductance (3-4pS) and Erev (75 mV), when the bath was perfused with a high K:low Na solution (ENa = 80 mV), were nearly equal in both patch configurations. Our results therefore indicate that the nystatin-induced open cell-attached patch can serve as an alternative approach to the excised inside-out patch when experiments require modulation of univalent ions in the cytosol.

  10. Comparison between symmetrical and asymmetrical single phase multilevel inverter with diode-clamped topology

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Nami, A.; Zare, F.

    2008-01-01

    In this paper, a different configuration based on different DC bus voltage for a diode-clamped multilevel inverter has been presented. Two different symmetrical and asymmetrical arrangements of a four-level diode clamped inverters have been compared, in order to find an optimum arrangement...... compared with the conventional four-level inverter and this will lead to the reduction of harmonic content of output voltage. A predictive current control technique has been carried out to verify the viability of new configuration. The advantages of this control method are simplicity and applicability...

  11. Five-level Z-source diode-clamped inverter

    DEFF Research Database (Denmark)

    Gao, F.; Loh, Poh Chiang; Blaabjerg, Frede

    2010-01-01

    This study proposes a five-level Z-source diode-clamped inverter designed with two intermediate Z-source networks connected between the dc input sources and rear-end inverter circuitry. By partially shorting the Z-source networks, new operating states not previously reported for two-level Z......-source inverter are introduced here for operating the proposed inverter with voltage buck–boost energy conversion ability and five-level phase voltage switching. These characteristic features are in fact always ensured at the inverter terminal output by simply adopting a properly designed carrier modulation...

  12. Clamping characteristics study on different types of clamping unit

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Zhiwei; Liu, Haichao; Xie, Pengcheng [College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing China 100029 (China); Yang, Weimin [College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing China 100029 (China); State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing China 100029 (China)

    2015-05-22

    Plastic products are becoming more and more widely used in aerospace, IT, digital electronics and many other fields. With the development of technology, the requirement of product precision is getting higher and higher. However, type and working performance of clamping unit play a decisive role in product precision. Clamping characteristics of different types of clamping unit are discussed in this article, which use finite element numerical analysis method through the software ABAQUS to study the clamping uniformity, and detect the clamping force repeatability precision. The result shows that compared with toggled three-platen clamping unit, clamping characteristics of internal circulation two-platen clamping unit are better, for instance, its mold cavity deformation and force that bars and mold parting surface suffered are more uniform, and its clamping uniformity and repeatability precision is also better.

  13. Pulsewidth-modulated 2-source neutral-point-clamped inverter

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Loh, Poh Chang; Gao, Feng

    2007-01-01

    This paper presents the careful integration of a newly proposed Z-source topological concept to the basic neutral-point-clamped (NPC) inverter topology for designing a three-level inverter with both voltage-buck and voltage-boost capabilities. The designed Z-source NPC inverter uses two unique X......-shaped inductance-capacitance (LC) impedance networks that are connected between two isolated dc input power sources and its inverter circuitry for boosting its AC output voltage. Through the design of an appropriate pulsewidth-modulation (PWM) algorithm, the two impedance networks can be short......-circuited sequentially (without shooting through the inverter full DC link) for implementing the ldquonearest-three-vectorrdquo modulation principle with minimized harmonic distortion and device commutations per half carrier cycle while performing voltage boosting. With only a slight modification to the inverter PWM...

  14. A Novel Neutral Point Clamped Full-Bridge Topology for Transformerless Photovoltaic Grid-Connected Inverters

    Directory of Open Access Journals (Sweden)

    M. Pakdel

    2017-04-01

    Full Text Available This paper presents a novel neutral point clamped full-bridge topology for transformerless photovoltaic grid-tied inverters. Transformerless grid-connected inverters have been used widely in recent years since they offer higher efficiency and lower costs. Ground leakage current suppression is the main issue which should be considered carefully in transformerless photovoltaic grid-connected inverters. Among different methods used to decline ground leakage current, neutral point clamped (NPC topologies are considered more useful and effective. In NPC topologies, the short-circuited output voltage at the freewheeling period is clamped to the middle of the DC bus voltage. Therefore, the common-mode voltage (CM will be constant at the whole switching period. Various NPC topologies such as H6 [1], HB-ZVR [2], oH5 [3], and PN-NPC [4] have been proposed. In this paper, a novel NPC topology is proposed which has lower power losses and higher efficiency over previous topologies. Furthermore, the proposed NPC topology exhibits a similar ground leakage current with the PN-NPC topology. The proposed NPC topology is analyzed theoretically using simulation studies and an experimental prototype is provided to verify theoretical analysis and simulation studies.

  15. Robotic multi-well planar patch-clamp for native and primary mammalian cells

    Science.gov (United States)

    Milligan, Carol J; Li, Jing; Sukumar, Piruthivi; Majeed, Yasser; Dallas, Mark L; English, Anne; Emery, Paul; Porter, Karen E; Smith, Andrew M; McFadzean, Ian; Beccano-Kelly, Dayne; Bahnasi, Yahya; Cheong, Alex; Naylor, Jacqueline; Zeng, Fanning; Liu, Xing; Gamper, Nikita; Jiang, Lin-Hua; Pearson, Hugh A; Peers, Chris; Robertson, Brian; Beech, David J

    2009-01-01

    Multi-well robotic planar patch-clamp has become common in drug development and safety programmes because it enables efficient and systematic testing of compounds against ion channels during voltage-clamp. It has not, however, been adopted significantly in other important areas of ion channel research, where conventional patch-clamp remains the favoured method. Here we show the wider potential of the multi-well approach with the capability for efficient intracellular solution exchange, describing protocols and success rates for recording from a range of native and primary mammalian cells derived from blood vessels, arthritic joints, and the immune and central nervous systems. The protocol involves preparing a suspension of single cells to be dispensed robotically into 4-8 microfluidic chambers each containing a glass chip with a small aperture. Under automated control, giga-seals and whole-cell access are achieved followed by pre-programmed routines of voltage paradigms and fast extracellular or intracellular solution exchange. Recording from 48 chambers usually takes 1-6 hr depending on the experimental design and yields 16-33 cell recordings. PMID:19197268

  16. Inertial piezoelectric linear motor driven by a single-phase harmonic wave with automatic clamping mechanism

    Science.gov (United States)

    He, Liangguo; Chu, Yuheng; Hao, Sai; Zhao, Xiaoyong; Dong, Yuge; Wang, Yong

    2018-05-01

    A novel, single-phase, harmonic-driven, inertial piezoelectric linear motor using an automatic clamping mechanism was designed, fabricated, and tested to reduce the sliding friction and simplify the drive mechanism and power supply control of the inertial motor. A piezoelectric bimorph and a flexible hinge were connected in series to form the automatic clamping mechanism. The automatic clamping mechanism was used as the driving and clamping elements. A dynamic simulation by Simulink was performed to prove the feasibility of the motor. The finite element method software COMSOL was used to design the structure of the motor. An experimental setup was built to validate the working principle and evaluate the performance of the motor. The prototype motor outputted a no-load velocity of 3.178 mm/s at a voltage of 220 Vp-p and a maximum traction force of 4.25 N under a preload force of 8 N. The minimum resolution of 1.14 μm was achieved at a driving frequency of 74 Hz, a driving voltage of 50 Vp-p, and a preload force of 0 N.

  17. Is early cord clamping, delayed cord clamping or cord milking best?

    Science.gov (United States)

    Vatansever, Binay; Demirel, Gamze; Ciler Eren, Elif; Erel, Ozcan; Neselioglu, Salim; Karavar, Hande Nur; Gundogdu, Semra; Ulfer, Gozde; Bahadir, Selcen; Tastekin, Ayhan

    2018-04-01

    To compare the antioxidant status of three cord clamping procedures (early clamping, delayed clamping and milking) by analyzing the thiol-disulfide balance. This randomized controlled study enrolled 189 term infants who were divided into three groups according to the cord clamping procedure: early clamping, delayed clamping and milking. Blood samples were collected from the umbilical arteries immediately after clamping, and the thiol/disulfide homeostasis was analyzed. The native and total thiol levels were significantly (p total thiol ratio was significantly (p = .026) lower in the delayed cord clamping and milking groups compared with the early clamping groups. Early cord clamping causes the production of more disulfide bonds and lower thiol levels, indicating that oxidation reactions are increased in the early cord clamping procedure compared with the delayed cord clamping and milking procedures. The oxidant capacity is greater with early cord clamping than with delayed clamping or cord milking. Delayed cord clamping or milking are beneficial in neonatal care, and we suggest that they be performed routinely in all deliveries.

  18. Enhanced Buck-Boost Three-Level Neutral-Point-Clamped Inverters

    DEFF Research Database (Denmark)

    Tan, K. K.; Gao, F.; Chiang Loh, Poh

    2009-01-01

    In traditional three-level neutral-point-clamped (NPC) inverters, a major issue is capacitor voltage imbalance, which results in low order harmonics. The compensation of the capacitor voltages often require additional control complexity, which cannot be conveniently implemented. The "alternative...... phase opposition disposition" (APOD) modulation method used in traditional NPC topologies also has lower harmonics performance as compared to the "phase disposition" (PD) modulation method.In this paper, we introduce a new three-level NPC topology that utilises the harmonically superior PD modulation...... method, with the ability to easily adjust for capacitor voltage imbalances. To further improve the boost capability of the three-level NPC inverters, another new topology introduces 2 additional diodes,achieving higher boost performance while totally eliminating thepossibility of capacitor voltage...

  19. LED-Based High-Voltage Lines Warning System

    Directory of Open Access Journals (Sweden)

    Eldar MUSA

    2013-04-01

    Full Text Available LED-based system, running with the current of high-voltage lines and converting the current flowing through the line into the light by using a toroid transformer, has been developed. The transformer’s primary winding is constituted by the high voltage power line. Toroidal core consists of two equal parts and the secondary windings are evenly placed on these two parts. The system is mounted on the high-voltage lines as a clamp. The secondary winding ends are connected in series by the connector on the clamp. LEDs are supplied by the voltage at the ends of secondary. Current flowing through highvoltage transmission lines is converted to voltage by the toroidal transformer and the light emitting LEDs are supplied with this voltage. The theory of the conversion of the current flowing through the line into the light is given. The system, running with the current of the line and converting the current into the light, has been developed. System has many application areas such as warning high voltage lines (warning winches to not hinder the high-voltage lines when working under the lines, warning planes to not touch the high-voltage lines, remote measurement of high-voltage line currents, and local illumination of the line area

  20. The Effect of an Added Mass on the Frequency Shifts of a Clamped-Clamped Microbeam for Bio-Mass Detection

    KAUST Repository

    Bouchaala, Adam M.

    2016-12-05

    We present analytical formulations to calculate the induced resonance frequency shifts of electrically actuated clamped-clamped microbeams due to an added mass. Based on the Euler-Bernoulli beam theory, we investigate the linear dynamic responses of the beams added masses, which are modeled as discrete point masses. Analytical expressions based on perturbation techniques and a one-mode Galerkin approximation are developed to calculate accurately the frequency shifts under a DC voltage as a function of the added mass and position. The analytical results are compared to numerical solution of the eigenvalue problem. Results are shown for the fundamental as well as the higher-order modes of the beams. The results indicate a significant increase in the frequency shift, and hence the sensitivity of detection, when scaling down to nano scale and using higher-order modes.

  1. The Effect of an Added Mass on the Frequency Shifts of a Clamped-Clamped Microbeam for Bio-Mass Detection

    KAUST Repository

    Bouchaala, Adam M.; Nayfeh, Ali H.; Younis, Mohammad I.

    2016-01-01

    We present analytical formulations to calculate the induced resonance frequency shifts of electrically actuated clamped-clamped microbeams due to an added mass. Based on the Euler-Bernoulli beam theory, we investigate the linear dynamic responses of the beams added masses, which are modeled as discrete point masses. Analytical expressions based on perturbation techniques and a one-mode Galerkin approximation are developed to calculate accurately the frequency shifts under a DC voltage as a function of the added mass and position. The analytical results are compared to numerical solution of the eigenvalue problem. Results are shown for the fundamental as well as the higher-order modes of the beams. The results indicate a significant increase in the frequency shift, and hence the sensitivity of detection, when scaling down to nano scale and using higher-order modes.

  2. Patch clamp study of mouse glomus cells using a whole carotid body.

    Science.gov (United States)

    Yamaguchi, Shigeki; Lande, Boris; Kitajima, Toshimitsu; Hori, Yuichi; Shirahata, Machiko

    2004-03-04

    Some electrophysiological characteristics of mouse glomus cells (DBA/2J strain) were investigated using an undissociated carotid body. The carotid body with major carotid arteries was placed in a recording chamber, and glomus cells were visualized with a water immersion lens combined with an infrared differential interference video camera. Patch clamp experiments revealed that voltage-gated outward current, but not inward current, was easily observed in glomus cells. Pharmacological experiments and the kinetics of the current suggest that outward current is via delayed rectifier, A type, and large conductance calcium-activated K channels. Furthermore, K current was reversibly attenuated by mild hypoxia. The results suggest electrophysiological similarities of glomus cells among the cat, the rat, and the DBA/2J mouse. The method appears useful for physiological experiments.

  3. Size-dependent dynamic stability analysis of microbeams actuated by piezoelectric voltage based on strain gradient elasticity theory

    Energy Technology Data Exchange (ETDEWEB)

    Sahmani, Saeid; Bahrami, Mohsen [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2015-01-15

    In the current paper, dynamic stability analysis of microbeams subjected to piezoelectric voltage is presented in which the microbeam is integrated with piezoelectric layers on the lower and upper surfaces. Both of the flutter and divergence instabilities of microbeams with clamped-clamped and clamped-free boundary conditions are predicted corresponding to various values of applied voltage. To take size effect into account, the classical Timoshenko beam theory in conjunction with strain gradient elasticity theory is utilized to develop nonclassical beam model containing three additional internal length scale parameters. By using Hamilton's principle, the higher-order governing differential equations and associated boundary conditions are derived. Afterward, generalized differential quadrature method is employed to discretize the size-dependent governing differential equations along with clamped-clamped and clamped-free end supports. The critical piezoelectric voltages corresponding to various values dimensionless length scale parameter are evaluated and compared with those predicted by the classical beam theory. It is revealed that in the case of clamped-free boundary conditions, the both of flutter and divergence instabilities occur. However, for the clamped-clamped microbeams, only divergence instability takes place.

  4. Highly selective water channel activity measured by voltage clamp: analysis of planar lipid bilayers reconstituted with purified AqpZ.

    Science.gov (United States)

    Pohl, P; Saparov, S M; Borgnia, M J; Agre, P

    2001-08-14

    Aquaporins are membrane channels selectively permeated by water or water plus glycerol. Conflicting reports have described ion conductance associated with some water channels, raising the question of whether ion conductance is a general property of the aquaporin family. To clarify this question, a defined system was developed to simultaneously measure water permeability and ion conductance. The Escherichia coli water channel aquaporin-Z (AqpZ) was studied, because it is a highly stable tetramer. Planar lipid bilayers were formed from unilamellar vesicles containing purified AqpZ. The hydraulic conductivity of bilayers made from the total extract of E. coli lipids increased 3-fold if reconstituted with AqpZ, but electric conductance was unchanged. No channel activity was detected under voltage-clamp conditions, indicating that less than one in 10(9) transport events is electrogenic. Microelectrode measurements were simultaneously undertaken adjacent to the membrane. Changes in sodium concentration profiles accompanying transmembrane water flow permitted calculation of the activation energies: 14 kcal/mol for protein-free lipid bilayers and 4 kcal/mol for lipid bilayers containing AqpZ. Neither the water permeability nor the electric conductivity exhibited voltage dependence. This sensitive system demonstrated that AqpZ is permeated by water but not charged ions and should permit direct analyses of putative electrogenic properties of other aquaporins.

  5. Neutral-point current modeling and control for Neutral-Point Clamped three-level converter drive with small DC-link capacitors

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, Sergio

    2011-01-01

    A Neutral-Point-Clamped (NPC) three-level inverter with small DC-link capacitors is presented in this paper. This inverter requires zero average neutral-point current for stable neutral-point potential. A simple carrier based modulation strategy is proposed for achieving zero average neutral...... drive with only 14 μF DC-link capacitors. A fast and stable performance of the neutral-point voltage controller is achieved and verified by experiments....

  6. Trans-Z-source and Γ-Z-source neutral-point-clamped inverters

    DEFF Research Database (Denmark)

    Wei, Mo; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    Z-source neutral-point-clamped (NPC) inverters are earlier proposed for obtaining voltage buck-boost and three-level switching simultaneously. Their performances are, however, constrained by a trade-off between their input-to-output gain and modulation ratio. This trade-off can lead to high...

  7. Modeling CICR in rat ventricular myocytes: voltage clamp studies

    Directory of Open Access Journals (Sweden)

    Palade Philip T

    2010-11-01

    Full Text Available Abstract Background The past thirty-five years have seen an intense search for the molecular mechanisms underlying calcium-induced calcium-release (CICR in cardiac myocytes, with voltage clamp (VC studies being the leading tool employed. Several VC protocols including lowering of extracellular calcium to affect Ca2+ loading of the sarcoplasmic reticulum (SR, and administration of blockers caffeine and thapsigargin have been utilized to probe the phenomena surrounding SR Ca2+ release. Here, we develop a deterministic mathematical model of a rat ventricular myocyte under VC conditions, to better understand mechanisms underlying the response of an isolated cell to calcium perturbation. Motivation for the study was to pinpoint key control variables influencing CICR and examine the role of CICR in the context of a physiological control system regulating cytosolic Ca2+ concentration ([Ca2+]myo. Methods The cell model consists of an electrical-equivalent model for the cell membrane and a fluid-compartment model describing the flux of ionic species between the extracellular and several intracellular compartments (cell cytosol, SR and the dyadic coupling unit (DCU, in which resides the mechanistic basis of CICR. The DCU is described as a controller-actuator mechanism, internally stabilized by negative feedback control of the unit's two diametrically-opposed Ca2+ channels (trigger-channel and release-channel. It releases Ca2+ flux into the cyto-plasm and is in turn enclosed within a negative feedback loop involving the SERCA pump, regulating[Ca2+]myo. Results Our model reproduces measured VC data published by several laboratories, and generates graded Ca2+ release at high Ca2+ gain in a homeostatically-controlled environment where [Ca2+]myo is precisely regulated. We elucidate the importance of the DCU elements in this process, particularly the role of the ryanodine receptor in controlling SR Ca2+ release, its activation by trigger Ca2+, and its

  8. Dynamic Pull-In Investigation of a Clamped-Clamped Nanoelectromechanical Beam under Ramp-Input Voltage and the Casimir Force

    Directory of Open Access Journals (Sweden)

    Amir R. Askari

    2014-01-01

    Full Text Available The influence of the Casimir excitation on dynamic pull-in instability of a nanoelectromechanical beam under ramp-input voltage is studied. The ramp-input actuation has applications in frequency sweeping of RF-N/MEMS. The presented model is nonlinear due to the inherent nonlinearity of electrostatics and the Casimir excitations as well as the geometric nonlinearity of midplane stretching. A Galerkin based reduced order modeling is utilized. It is found that the calculated dynamic pull-in ramp input voltage leads to dynamic pull-in step input voltage by increasing the slope of voltage-time diagram. This fact is utilized to verify the results of present study.

  9. PWM Regulation of Grid-Tied PV System on the Base of Photovoltaic-Fed Diode-Clamped Inverters

    Directory of Open Access Journals (Sweden)

    Oleschuk V.I.

    2015-12-01

    Full Text Available Investigation of grid-tied photovoltaic system on the base of two diode-clamped inverters, controlled by specific algorithms of pulse-width modulation (PWM, has been done. This system includes two strings of photovoltaic panels feeding two diode-clamped inverters. The outputs of inverters are connected with the corresponding windings on the primary side of three-phase transformer, connected with a grid. In order to reduce phase voltage distortion and to increase efficiency of operation of the system, special scheme of control and modulation of inverters has been used, providing minimization of common-mode voltages and voltage waveforms symmetries under different operating conditions. Detailed simulation of processes in this photovoltaic-fed power conversion system has been executed. The results of simulations verify good performance of photovoltaic system regulated in accordance with specific strategy of control and modulation.

  10. Planar patch clamp: advances in electrophysiology.

    Science.gov (United States)

    Brüggemann, Andrea; Farre, Cecilia; Haarmann, Claudia; Haythornthwaite, Ali; Kreir, Mohamed; Stoelzle, Sonja; George, Michael; Fertig, Niels

    2008-01-01

    Ion channels have gained increased interest as therapeutic targets over recent years, since a growing number of human and animal diseases have been attributed to defects in ion channel function. Potassium channels are the largest and most diverse family of ion channels. Pharmaceutical agents such as Glibenclamide, an inhibitor of K(ATP) channel activity which promotes insulin release, have been successfully sold on the market for many years. So far, only a small group of the known ion channels have been addressed as potential drug targets. The functional testing of drugs on these ion channels has always been the bottleneck in the development of these types of pharmaceutical compounds.New generations of automated patch clamp screening platforms allow a higher throughput for drug testing and widen this bottleneck. Due to their planar chip design not only is a higher throughput achieved, but new applications have also become possible. One of the advantages of planar patch clamp is the possibility of perfusing the intracellular side of the membrane during a patch clamp experiment in the whole-cell configuration. Furthermore, the extracellular membrane remains accessible for compound application during the experiment.Internal perfusion can be used not only for patch clamp experiments with cell membranes, but also for those with artificial lipid bilayers. In this chapter we describe how internal perfusion can be applied to potassium channels expressed in Jurkat cells, and to Gramicidin channels reconstituted in a lipid bilayer.

  11. Relaxation of Isolated Ventricular Cardiomyocytes by a Voltage-Dependent Process

    Science.gov (United States)

    Bridge, John H. B.; Spitzer, Kenneth W.; Ershler, Philip R.

    1988-08-01

    Cell contraction and relaxation were measured in single voltage-clamped guinea pig cardiomyocytes to investigate the contribution of sarcolemmal Na+-Ca2+ exchange to mechanical relaxation. Cells clamped from -80 to 0 millivolts displayed initial phasic and subsequent tonic contractions; caffeine reduced or abolished the phasic and enlarged the tonic contraction. The rate of relaxation from tonic contractions was steeply voltage-dependent and was significantly slowed in the absence of a sarcolemmal Na+ gradient. Tonic contractions elicited in the absence of a Na+ gradient promptly relaxed when external Na+ was applied, reflecting activation of Na+-Ca2+ exchange. It appears that a voltage-dependent Na+-Ca2+ exchange can rapidly mechanically relax mammalian heart muscle.

  12. Photovoltaic panel clamp

    Science.gov (United States)

    Mittan, Margaret Birmingham [Oakland, CA; Miros, Robert H. J. [Fairfax, CA; Brown, Malcolm P [San Francisco, CA; Stancel, Robert [Loss Altos Hills, CA

    2012-06-05

    A photovoltaic panel clamp includes an upper and lower section. The interface between the assembled clamp halves and the module edge is filled by a flexible gasket material, such as EPDM rubber. The gasket preferably has small, finger like protrusions that allow for easy insertion onto the module edge while being reversed makes it more difficult to remove them from the module once installed. The clamp includes mounting posts or an integral axle to engage a bracket. The clamp also may include a locking tongue to secure the clamp to a bracket.

  13. Selective Arterial Clamping Versus Hilar Clamping for Minimally Invasive Partial Nephrectomy.

    Science.gov (United States)

    Yezdani, Mona; Yu, Sue-Jean; Lee, David I

    2016-05-01

    Partial nephrectomy has become an accepted treatment of cT1 renal masses as it provides improved long-term renal function compared to radical nephrectomy (Campbell et al. J Urol. 182:1271-9, 2009). Hilar clamping is utilized to help reduce bleeding and improve visibility during tumor resection. However, concern over risk of kidney injury with hilar clamping has led to new techniques to reduce length of warm ischemia time (WIT) during partial nephrectomy. These techniques have progressed over the years starting with early hilar unclamping, controlled hypotension during tumor resection, selective arterial clamping, minimal margin techniques, and off-clamp procedures. Selective arterial clamping has progressed significantly over the years. The main question is what are the exact short- and long-term renal effects from increasing clamp time. Moreover, does it make sense to perform these more time-consuming or more complex procedures if there is no long-term preservation of kidney function? More recent studies have shown no difference in renal function 6 months from surgery when selective arterial clamping or even hilar clamping is employed, although there is short-term improved decline in estimated glomerular filtration rate (eGFR) with selective clamping and off-clamp techniques (Komninos et al. BJU Int. 115:921-8, 2015; Shah et al. 117:293-9, 2015; Kallingal et al. BJU Int. doi: 10.1111/bju.13192, 2015). This paper reviews the progression of total hilar clamping to selective arterial clamping (SAC) and the possible difference its use makes on long-term renal function. SAC may be attempted based on surgeon's decision-making, but may be best used for more complex, larger, more central or hilar tumors and in patients who have renal insufficiency at baseline or a solitary kidney.

  14. High Performance ZVT with Bus Clamping Modulation Technique for Single Phase Full Bridge Inverters

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yinglai; Ayyanar, Raja

    2016-03-20

    This paper proposes a topology based on bus clamping modulation and zero-voltage-transition (ZVT) technique to realize zero-voltage-switching (ZVS) for all the main switches of the full bridge inverters, and inherent ZVS and/or ZCS for the auxiliary switches. The advantages of the strategy include significant reduction in the turn-on loss of the ZVT auxiliary switches which typically account for a major part of the total loss in other ZVT circuits, and reduction in the voltage ratings of auxiliary switches. The modulation scheme and the commutation stages are analyzed in detail. Finally, a 1kW, 500 kHz switching frequency inverter of the proposed topology using SiC MOSFETs has been built to validate the theoretical analysis. The ZVT with bus clamping modulation technique of fixed timing and adaptive timing schemes are implemented in DSP TMS320F28335 resulting in full ZVS for the main switches in the full bridge inverter. The proposed scheme can save up to 33 % of the switching loss compared with no ZVT case.

  15. Monitoring Voltage-Dependent Charge Displacement of Shaker B-IR K+ Ion Channels Using Radio Frequency Interrogation

    OpenAIRE

    Dharia, Sameera; Rabbitt, Richard D.

    2011-01-01

    Here we introduce a new technique that probes voltage-dependent charge displacements of excitable membrane-bound proteins using extracellularly applied radio frequency (RF, 500 kHz) electric fields. Xenopus oocytes were used as a model cell for these experiments, and were injected with cRNA encoding Shaker B-IR (ShB-IR) K(+) ion channels to express large densities of this protein in the oocyte membranes. Two-electrode voltage clamp (TEVC) was applied to command whole-cell membrane potential a...

  16. Neuroprotective effect of interleukin-6 regulation of voltage-gated Na+ channels of cortical neurons is time- and dose-dependent

    Directory of Open Access Journals (Sweden)

    Wei Xia

    2015-01-01

    Full Text Available Interleukin-6 has been shown to be involved in nerve injury and nerve regeneration, but the effects of long-term administration of high concentrations of interleukin-6 on neurons in the central nervous system is poorly understood. This study investigated the effects of 24 hour exposure of interleukin-6 on cortical neurons at various concentrations (0.1, 1, 5 and 10 ng/mL and the effects of 10 ng/mL interleukin-6 exposure to cortical neurons for various durations (2, 4, 8, 24 and 48 hours by studying voltage-gated Na + channels using a patch-clamp technique. Voltage-clamp recording results demonstrated that interleukin-6 suppressed Na + currents through its receptor in a time- and dose-dependent manner, but did not alter voltage-dependent activation and inactivation. Current-clamp recording results were consistent with voltage-clamp recording results. Interleukin-6 reduced the action potential amplitude of cortical neurons, but did not change the action potential threshold. The regulation of voltage-gated Na + channels in rat cortical neurons by interleukin-6 is time- and dose-dependent.

  17. High voltage dc-dc converter with dynamic voltage regulation and decoupling during load-generated arcs

    Science.gov (United States)

    Shimer, Daniel W.; Lange, Arnold C.

    1995-01-01

    A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

  18. High voltage dc--dc converter with dynamic voltage regulation and decoupling during load-generated arcs

    Science.gov (United States)

    Shimer, D.W.; Lange, A.C.

    1995-05-23

    A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules. 5 Figs.

  19. Duo-Active-Neutral-Point-Clamped Multilevel Converter: An Exploration of the Fundamental Topology and Experimental Verification

    DEFF Research Database (Denmark)

    Dargahi, Vahid; Corzine, Keith A.; Enslin, Johan H.

    2018-01-01

    For medium-voltage (MV) industrial applications such as the HVDC and adjustable-speed ac-motor drives, the multilevel voltage-source converters are deemed the predominant topologies. One of the promising derived-topologies from the neutral-point-clamped (NPC) configuration is the active NPC (ANPC......) structure with an improved balanced lossdistribution performance. This paper introduces duo-ANPC (D-ANPC) converter topology, which is controlled with a new modulation technique. The suggested control method regulates the flying capacitor (FC) voltages naturally at their reference values and preserves...

  20. Multi-mode excitation of a clamped–clamped microbeam resonator

    KAUST Repository

    Younis, Mohammad I.

    2015-02-18

    We present modeling and simulation of the nonlinear dynamics of a microresonator subjected to two-source electrostatic excitation. The resonator is composed of a clamped–clamped beam excited by a DC voltage load superimposed to two AC voltage loads of different frequencies. One frequency is tuned close to the first natural frequency of the beam and the other is close to the third (second symmetric) natural frequency. A multi-mode Galerkin procedure is applied to extract a reduced-order model, which forms the basis of the numerical simulations. Time history response, Poincare’ sections, Fast Fourier Transforms FFT, and bifurcation diagrams are used to reveal the dynamics of the system. The results indicate complex nonlinear phenomena, which include quasiperiodic motion, torus bifurcations, and modulated chaotic attractors.

  1. Applications of Dynamic Clamp to Cardiac Arrhythmia Research: Role in Drug Target Discovery and Safety Pharmacology Testing

    Directory of Open Access Journals (Sweden)

    Francis A. Ortega

    2018-01-01

    Full Text Available Dynamic clamp, a hybrid-computational-experimental technique that has been used to elucidate ionic mechanisms underlying cardiac electrophysiology, is emerging as a promising tool in the discovery of potential anti-arrhythmic targets and in pharmacological safety testing. Through the injection of computationally simulated conductances into isolated cardiomyocytes in a real-time continuous loop, dynamic clamp has greatly expanded the capabilities of patch clamp outside traditional static voltage and current protocols. Recent applications include fine manipulation of injected artificial conductances to identify promising drug targets in the prevention of arrhythmia and the direct testing of model-based hypotheses. Furthermore, dynamic clamp has been used to enhance existing experimental models by addressing their intrinsic limitations, which increased predictive power in identifying pro-arrhythmic pharmacological compounds. Here, we review the recent advances of the dynamic clamp technique in cardiac electrophysiology with a focus on its future role in the development of safety testing and discovery of anti-arrhythmic drugs.

  2. Reproducible and controllable induction voltage adder for scaled beam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Yasuo; Nakajima, Mitsuo; Horioka, Kazuhiko [Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

    2016-08-15

    A reproducible and controllable induction adder was developed using solid-state switching devices and Finemet cores for scaled beam compression experiments. A gate controlled MOSFET circuit was developed for the controllable voltage driver. The MOSFET circuit drove the induction adder at low magnetization levels of the cores which enabled us to form reproducible modulation voltages with jitter less than 0.3 ns. Preliminary beam compression experiments indicated that the induction adder can improve the reproducibility of modulation voltages and advance the beam physics experiments.

  3. Insulated pipe clamp design

    International Nuclear Information System (INIS)

    Anderson, M.J.; Hyde, L.L.; Wagner, S.E.; Severud, L.K.

    1980-01-01

    Thin wall large diameter piping for breeder reactor plants can be subjected to significant thermal shocks during reactor scrams and other upset events. On the Fast Flux Test Facility, the addition of thick clamps directly on the piping was undesired because the differential metal temperatures between the pipe wall and the clamp could have significantly reduced the pipe thermal fatigue life cycle capabilities. Accordingly, an insulated pipe clamp design concept was developed. The design considerations and methods along with the development tests are presented. Special considerations to guard against adverse cracking of the insulation material, to maintain the clamp-pipe stiffness desired during a seismic event, to minimize clamp restraint on the pipe during normal pipe heatup, and to resist clamp rotation or spinning on the pipe are emphasized

  4. Computer Simulation Model to Train Medical Personnel on Glucose Clamp Procedures.

    Science.gov (United States)

    Maghoul, Pooya; Boulet, Benoit; Tardif, Annie; Haidar, Ahmad

    2017-10-01

    A glucose clamp procedure is the most reliable way to quantify insulin pharmacokinetics and pharmacodynamics, but skilled and trained research personnel are required to frequently adjust the glucose infusion rate. A computer environment that simulates glucose clamp experiments can be used for efficient personnel training and development and testing of algorithms for automated glucose clamps. We built 17 virtual healthy subjects (mean age, 25±6 years; mean body mass index, 22.2±3 kg/m 2 ), each comprising a mathematical model of glucose regulation and a unique set of parameters. Each virtual subject simulates plasma glucose and insulin concentrations in response to intravenous insulin and glucose infusions. Each virtual subject provides a unique response, and its parameters were estimated from combined intravenous glucose tolerance test-hyperinsulinemic-euglycemic clamp data using the Bayesian approach. The virtual subjects were validated by comparing their simulated predictions against data from 12 healthy individuals who underwent a hyperglycemic glucose clamp procedure. Plasma glucose and insulin concentrations were predicted by the virtual subjects in response to glucose infusions determined by a trained research staff performing a simulated hyperglycemic clamp experiment. The total amount of glucose infusion was indifferent between the simulated and the real subjects (85±18 g vs. 83±23 g; p=NS) as well as plasma insulin levels (63±20 mU/L vs. 58±16 mU/L; p=NS). The virtual subjects can reliably predict glucose needs and plasma insulin profiles during hyperglycemic glucose clamp conditions. These virtual subjects can be used to train personnel to make glucose infusion adjustments during clamp experiments. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

  5. 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...

  6. Cell-Detection Technique for Automated Patch Clamping

    Science.gov (United States)

    McDowell, Mark; Gray, Elizabeth

    2008-01-01

    A unique and customizable machinevision and image-data-processing technique has been developed for use in automated identification of cells that are optimal for patch clamping. [Patch clamping (in which patch electrodes are pressed against cell membranes) is an electrophysiological technique widely applied for the study of ion channels, and of membrane proteins that regulate the flow of ions across the membranes. Patch clamping is used in many biological research fields such as neurobiology, pharmacology, and molecular biology.] While there exist several hardware techniques for automated patch clamping of cells, very few of those techniques incorporate machine vision for locating cells that are ideal subjects for patch clamping. In contrast, the present technique is embodied in a machine-vision algorithm that, in practical application, enables the user to identify good and bad cells for patch clamping in an image captured by a charge-coupled-device (CCD) camera attached to a microscope, within a processing time of one second. Hence, the present technique can save time, thereby increasing efficiency and reducing cost. The present technique involves the utilization of cell-feature metrics to accurately make decisions on the degree to which individual cells are "good" or "bad" candidates for patch clamping. These metrics include position coordinates (x,y) in the image plane, major-axis length, minor-axis length, area, elongation, roundness, smoothness, angle of orientation, and degree of inclusion in the field of view. The present technique does not require any special hardware beyond commercially available, off-the-shelf patch-clamping hardware: A standard patchclamping microscope system with an attached CCD camera, a personal computer with an imagedata- processing board, and some experience in utilizing imagedata- processing software are all that are needed. A cell image is first captured by the microscope CCD camera and image-data-processing board, then the image

  7. Enhanced DC-Link Capacitor Voltage Balancing Control of DC–AC Multilevel Multileg Converters

    DEFF Research Database (Denmark)

    Busquets-Monge, Sergio; Maheshwari, Ram Krishan; Nicolas-Apruzzese, Joan

    2015-01-01

    This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc-link vol......This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc...

  8. Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid.

    Science.gov (United States)

    Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

    2016-07-05

    The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane.

  9. Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid

    Science.gov (United States)

    Sakata, Souhei; Jinno, Yuka; Kawanabe, Akira; Okamura, Yasushi

    2016-01-01

    The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane. PMID:27330112

  10. Enhanced Buck–Boost Neutral-Point-Clamped Inverters With Simple Capacitive-Voltage Balancing

    DEFF Research Database (Denmark)

    Tan, Kuan Khoon; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    introduced for extending the inverters’ variation range to include voltageboost operation, but they generally require the inclusion of large passive components or have not yet been optimized in terms of waveform quality. The balancing of their capacitive voltages using a simple technique has also not yet...... simultaneously, two new buck–boost NPC inverters with simple capacitive-voltage-balancing capability are proposed. Both inverters are demonstrated to exhibit a doubling of voltage gain, with one of them also shown to produce a better output waveform quality. Simulation and experimental results are provided...

  11. First high-voltage measurements using Ca{sup +} ions at the ALIVE experiment

    Energy Technology Data Exchange (ETDEWEB)

    König, K., E-mail: kkoenig@ikp.tu-darmstadt.de [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Geppert, Ch. [Universität Mainz, Institut für Kernchemie (Germany); Krämer, J.; Maaß, B. [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Otten, E. W. [Universität Mainz, Institut für Physik (Germany); Ratajczyk, T.; Nörtershäuser, W. [Technische Universität Darmstadt, Institut für Kernphysik (Germany)

    2017-11-15

    Many physics experiments depend on accurate high-voltage measurements to determine for example the exact retardation potential of an electron spectrometer as in the KATRIN experiment or the acceleration voltage of the ions at ISOL facilities. Until now only precision high-voltage dividers can be used to measure voltages up to 65 kV with an accuracy of 1 ppm. However, these dividers need frequent calibration and cross-checking and the direct traceability is not given. In this article we will describe the status of an experiment which aims to measure high voltages using collinear laser spectroscopy and which has the potential to provide a high-voltage standard and hence, a calibration source for precision high-voltage dividers on the 1 ppm level.

  12. Dimerization of the voltage-sensing phosphatase controls its voltage-sensing and catalytic activity.

    Science.gov (United States)

    Rayaprolu, Vamseedhar; Royal, Perrine; Stengel, Karen; Sandoz, Guillaume; Kohout, Susy C

    2018-05-07

    Multimerization is a key characteristic of most voltage-sensing proteins. The main exception was thought to be the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP). In this study, we show that multimerization is also critical for Ci-VSP function. Using coimmunoprecipitation and single-molecule pull-down, we find that Ci-VSP stoichiometry is flexible. It exists as both monomers and dimers, with dimers favored at higher concentrations. We show strong dimerization via the voltage-sensing domain (VSD) and weak dimerization via the phosphatase domain. Using voltage-clamp fluorometry, we also find that VSDs cooperate to lower the voltage dependence of activation, thus favoring the activation of Ci-VSP. Finally, using activity assays, we find that dimerization alters Ci-VSP substrate specificity such that only dimeric Ci-VSP is able to dephosphorylate the 3-phosphate from PI(3,4,5)P 3 or PI(3,4)P 2 Our results indicate that dimerization plays a significant role in Ci-VSP function. © 2018 Rayaprolu et al.

  13. Single-Carrier Modulation for Neutral-Point-Clamped Inverters in Three-Phase Transformerless Photovoltaic Systems

    DEFF Research Database (Denmark)

    Guo, Xiaoqiang; Cavalcanti, Marcelo C.; Farias, Alexandre M.

    2013-01-01

    Modulation strategy is one of the most important issues for three-level neutral-point-clamped inverters in three-phase transformerless photovoltaic systems. A challenge for modulation is how to keep the common-mode voltages constant to reduce the leakage currents. A single-carrier modulation...... strategy is proposed. It has a very simple structure, and the common-mode voltages can be kept constant with no need of complex space-vector modulation or multicarrier pulsewidth modulation. Experimental results verify the theoretical analysis and the effectiveness of the presented method....

  14. Contributions of counter-charge in a potassium channel voltage-sensor domain

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Galpin, Jason D; Niciforovic, Ana P

    2011-01-01

    Voltage-sensor domains couple membrane potential to conformational changes in voltage-gated ion channels and phosphatases. Highly coevolved acidic and aromatic side chains assist the transfer of cationic side chains across the transmembrane electric field during voltage sensing. We investigated...... the functional contribution of negative electrostatic potentials from these residues to channel gating and voltage sensing with unnatural amino acid mutagenesis, electrophysiology, voltage-clamp fluorometry and ab initio calculations. The data show that neutralization of two conserved acidic side chains...

  15. 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...

  16. Use of the Satinsky clamp for hilar clamping during robotic partial nephrectomy: indications, technique, and multi-center outcomes.

    Science.gov (United States)

    Abdullah, Newaj; Rahbar, Haider; Barod, Ravi; Dalela, Deepansh; Larson, Jeff; Johnson, Michael; Mass, Alon; Zargar, Homayoun; Kaouk, Jihad; Allaf, Mohamad; Bhayani, Sam; Stifelman, Michael; Rogers, Craig

    2017-03-01

    A Satinsky clamp may be a backup option for hilar clamping during robotic partial nephrectomy (RPN) if there are challenges with application of bulldog clamps, but there are potential safety concerns. We evaluate outcomes of RPN using Satinsky vs. bulldog clamps, and provide tips for safe use of the Satinsky as a backup option. Using a multi-center database, we identified 1073 patients who underwent RPN between 2006 and 2013, and had information available about method of hilar clamping (bulldog clamp vs. Satinsky clamp). Patient baseline characteristics, tumor features, and perioperative outcomes were compared between the Satinsky and bulldog clamp groups. A Satinsky clamp was used for hilar clamping in 94 (8.8 %) RPN cases, and bulldog clamps were used in 979 (91.2 %) cases. The use of a Satinsky clamp was associated with greater operative time (198 vs. 175 min, p hilar clamping during challenging RPN cases, but requires careful technique, and was rarely necessary.

  17. Automatic tracking of cells for video microscopy in patch clamp experiments.

    Science.gov (United States)

    Peixoto, Helton M; Munguba, Hermany; Cruz, Rossana M S; Guerreiro, Ana M G; Leao, Richardson N

    2014-06-20

    Visualisation of neurons labeled with fluorescent proteins or compounds generally require exposure to intense light for a relatively long period of time, often leading to bleaching of the fluorescent probe and photodamage of the tissue. Here we created a technique to drastically shorten light exposure and improve the targeting of fluorescent labeled cells that is specially useful for patch-clamp recordings. We applied image tracking and mask overlay to reduce the time of fluorescence exposure and minimise mistakes when identifying neurons. Neurons are first identified according to visual criteria (e.g. fluorescence protein expression, shape, viability etc.) and a transmission microscopy image Differential Interference Contrast (DIC) or Dodt contrast containing the cell used as a reference for the tracking algorithm. A fluorescence image can also be acquired later to be used as a mask (that can be overlaid on the target during live transmission video). As patch-clamp experiments require translating the microscope stage, we used pattern matching to track reference neurons in order to move the fluorescence mask to match the new position of the objective in relation to the sample. For the image processing we used the Open Source Computer Vision (OpenCV) library, including the Speeded-Up Robust Features (SURF) for tracking cells. The dataset of images (n = 720) was analyzed under normal conditions of acquisition and with influence of noise (defocusing and brightness). We validated the method in dissociated neuronal cultures and fresh brain slices expressing Enhanced Yellow Fluorescent Protein (eYFP) or Tandem Dimer Tomato (tdTomato) proteins, which considerably decreased the exposure to fluorescence excitation, thereby minimising photodamage. We also show that the neuron tracking can be used in differential interference contrast or Dodt contrast microscopy. The techniques of digital image processing used in this work are an important addition to the set of microscopy

  18. Radial wedge flange clamp

    Science.gov (United States)

    Smith, Karl H.

    2002-01-01

    A radial wedge flange clamp comprising a pair of flanges each comprising a plurality of peripheral flat wedge facets having flat wedge surfaces and opposed and mating flat surfaces attached to or otherwise engaged with two elements to be joined and including a series of generally U-shaped wedge clamps each having flat wedge interior surfaces and engaging one pair of said peripheral flat wedge facets. Each of said generally U-shaped wedge clamps has in its opposing extremities apertures for the tangential insertion of bolts to apply uniform radial force to said wedge clamps when assembled about said wedge segments.

  19. Battery charger with a capacitor-diode clamped LLC resonant converter

    OpenAIRE

    Tsang, C.; Bingham, C.; Foster, M. P.; Stone, D.; Leech, J.

    2016-01-01

    The paper proposes a novel battery charger through use of\\ud two serially-connected LLC resonant converters. The first\\ud stage utilises a capacitor-diode clamped LLC resonant\\ud converter which allows operation in both constant voltage\\ud (CV) and constant current (CC) modes, as found in most\\ud battery chargers, to be realised, whilst the second stage\\ud provides the necessary gain and line and load regulation. A\\ud design example is included that demonstrates the resulting\\ud converter top...

  20. High performance control strategy for single-phase three-level neutral-point-clamped traction four-quadrant converters

    DEFF Research Database (Denmark)

    Kejian, Song; Konstantinou, Georgios; Jing, Li

    2017-01-01

    Operational data from Chinese railways indicate a number of challenges for traction four-quadrant converter (4QC) control including low-order voltage and current harmonics and reference tracking. A control strategy for a single-phase three-level neutral-point-clamped 4QC employed in the electric...

  1. Lotus birth, a holistic approach on physiological cord clamping.

    Science.gov (United States)

    Zinsser, Laura A

    2018-04-01

    The positive effects of delayed cord clamping (DCC) has been extensively researched. DCC means: waiting at least one minute after birth before clamping and cutting the cord or till the pulsation has stopped. With physiological clamping and cutting (PCC) the clamping and cutting can happen at the earliest after the pulsation has stopped. With a Lotus birth, no clamping and cutting of the cord is done. A woman called Clair Lotus Day imitated the holistic approach of PCC from an anthropoid ape in 1974. The chimpanzee did not separate the placenta from the newborn. The aim of this case report is to discuss and learn a different approach in the third stage of labour. Three cases of Lotus birth by human beings were observed. All three women gave birth in an out-of-hospital setting and had ambulant postnatal care. The placenta was washed, salted and herbs were put on 2-3h post partum. The placenta was wrapped in something that absorbs the moisture. The salting was repeated with a degreasing frequency depending on moistness of the placenta. On life day six all three Lotus babies experiences a natural separation of the cord. All three Lotus birth cases were unproblematic, no special incidence occurred. One should differentiate between early cord clamping (ECC), delayed cord clamping (DCC) and physiological cord clamping (PCC). Lotus birth might lead to an optimisation of the bonding and attachment. Research is needed in the areas of both PCC and Lotus birth. Copyright © 2017 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  2. Single stage buck-boost DC-AC neutral point clamped inverter

    DEFF Research Database (Denmark)

    Mo, Wei; Loh, Poh Chiang; Andrew, A.

    2012-01-01

    This paper proposes a new single stage buck-boost DC-AC neutral point clamped inverter topology which integrates the cascaded configurations of recently introduced inductor-capacitor-capacitor-transformer impedance source network (by Adamowicz) and classic NPC configuration. As a consequence......, it has enhanced buck-boost functionality and low output voltage distortions compared to the traditional Z-source inverter; it has continuous input current which reduces the source stress and inverter noise; it also contains two built-in capacitors which can block the DC current in the transformer...... windings thus preventing the core from saturation; lowers the voltage stresses and power losses of inverter switches and reduces the sizes of filtering devices and as well as obtains better output performance compared to the original two-level Z-source inverters. A phase disposition pulse width modulation...

  3. Modulation Methods for Three-level Neutral-Point-Clamped Inverter Achieving Stress Redistribution under Moderate Modulation Index

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2016-01-01

    This letter investigates the loss and thermal behaviors of a three-level neutral-point-clamped (3L-NPC) inverter undergoing moderate modulation index, which is typically presented during minor voltage sags of the power grid or speed changes of the electric machines. A series of new space vector m...

  4. Monitoring voltage-sensitive membrane impedance change using radio frequency interrogation.

    Science.gov (United States)

    Dharia, Sameera; Rabbitt, Richard D

    2010-01-01

    Here we present a new technique to monitor dynamic conformational changes in voltage-sensitive membrane-bound proteins using radio frequency (RF) impedance measurements. Xenopus oocytes were transfected to express ShakerB-IR K(+) ion channels, and step changes in membrane potential were applied using two-electrode voltage clamp (TEVC). Simultaneously, bipolar extracellular electrodes were used to measure the RF electrical impedance across the cell (300 kHz - 1 MHz). RF current will either pass through the media, around the cell, or displace charge across the cell membrane. The change in displacement current in the cell membrane during voltage clamp resulted in measurable RF impedance change. RF impedance change during DC membrane depolarization was significantly greater in ShakerB-IR expressing oocytes than in endogenous controls at 300 kHz, 500 kHz and, to a lesser extent, 1 MHz. Since the RF were too high to modulate ShakerB-IR protein conformational state (e.g. open channel probability), impedance changes are interpreted as reflections of voltage-dependent protein conformation and associated biophysics such as ion-channel dipole interactions, fluctuations in bound water, or charged lipid head-group rotations.

  5. Neutral-point voltage dynamic model of three-level NPC inverter for reactive load

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, Sergio

    2012-01-01

    A three-level neutral-point-clamped inverter needs a controller for the neutral-point voltage. Typically, the controller design is based on a dynamic model. The dynamic model of the neutral-point voltage depends on the pulse width modulation technique used for the inverter. A pulse width modulati...

  6. Insulated pipe clamp design

    International Nuclear Information System (INIS)

    Anderson, M.J.; Hyde, L.L.; Wagner, S.E.; Severud, L.K.

    1980-01-01

    Thin wall large diameter piping for breeder reactor plants can be subjected to significant thermal shocks during reactor scrams and other upset events. On the Fast Flux Test Facility, the addition of thick clamps directly on the piping was undesired because the differential metal temperatures between the pipe wall and the clamp could have significantly reduced the pipe thermal fatigue life cycle capabilities. Accordingly, an insulated pipe clamp design concept was developed. 5 refs

  7. Theoretical and experimental nonlinear dynamics of a clamped-clamped beam MEMS resonator

    NARCIS (Netherlands)

    Mestrom, R.M.C.; Fey, R.H.B.; Nijmeijer, H.

    2008-01-01

    Microelectromechanical resonators feature nonlineardynamic responses. A first-principles based modeling approach is proposed for a clamped-clamped beam resonator. Starting from the partial differential equation for the beam including geometric and electrostatic nonlinear effects, a reduced-order

  8. A novel voltage clamp circuit for the measurement of transistor dynamic on-resistance

    NARCIS (Netherlands)

    Gelagaev, R.; Jacqmaer, P.; Everts, J.; Driesen, Johan

    2012-01-01

    For determining the dynamic on-resistance Rdyn,on of a power transistor, the voltage and current waveforms have to be measured during the switching operation. In measurements of voltage waveforms, using an oscilloscope, the characteristics of an amplifier inside the oscilloscope are distorted when

  9. Solar array experiments on the SPHINX satellite. [Space Plasma High voltage INteraction eXperiment satellite

    Science.gov (United States)

    Stevens, N. J.

    1974-01-01

    The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations: the edge illuminated-multijunction cells, the teflon encased cells, and the violet cells.

  10. A Hybrid Model for Safety Pharmacology on an Automated Patch Clamp Platform: Using Dynamic Clamp to Join iPSC-Derived Cardiomyocytes and Simulations of Ik1 Ion Channels in Real-Time

    Directory of Open Access Journals (Sweden)

    Birgit Goversen

    2018-01-01

    Full Text Available An important aspect of the Comprehensive In Vitro Proarrhythmia Assay (CiPA proposal is the use of human stem cell-derived cardiomyocytes and the confirmation of their predictive power in drug safety assays. The benefits of this cell source are clear; drugs can be tested in vitro on human cardiomyocytes, with patient-specific genotypes if needed, and differentiation efficiencies are generally excellent, resulting in a virtually limitless supply of cardiomyocytes. There are, however, several challenges that will have to be surmounted before successful establishment of hSC-CMs as an all-round predictive model for drug safety assays. An important factor is the relative electrophysiological immaturity of hSC-CMs, which limits arrhythmic responses to unsafe drugs that are pro-arrhythmic in humans. Potentially, immaturity may be improved functionally by creation of hybrid models, in which the dynamic clamp technique joins simulations of lacking cardiac ion channels (e.g., IK1 with hSC-CMs in real-time during patch clamp experiments. This approach has been used successfully in manual patch clamp experiments, but throughput is low. In this study, we combined dynamic clamp with automated patch clamp of iPSC-CMs in current clamp mode, and demonstrate that IK1 conductance can be added to iPSC-CMs on an automated patch clamp platform, resulting in an improved electrophysiological maturity.

  11. 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...

  12. A high-voltage triggered pseudospark discharge experiment

    International Nuclear Information System (INIS)

    Ramaswamy, K.; Destler, W.W.; Rodgers, J.

    1996-01-01

    The design and execution of a pulsed high-voltage (350 endash 400 keV) triggered pseudospark discharge experiment is reported. Experimental studies were carried out to obtain an optimal design for stable and reliable pseudospark operation in a high-voltage regime (approx-gt 350 kV). Experiments were performed to determine the most suitable fill gas for electron-beam formation. The pseudospark discharge is initiated by a trigger mechanism involving a flashover between the trigger electrode and hollow cathode housing. Experimental results characterizing the electron-beam energy using the range-energy method are reported. Source size imaging was carried out using an x-ray pinhole camera and a novel technique using Mylar as a witness plate. It was experimentally determined that strong pinching occurred later in time and was associated with the lower-energy electrons. copyright 1996 American Institute of Physics

  13. Nanosecond electric pulses differentially affect inward and outward currents in patch clamped adrenal chromaffin cells.

    Directory of Open Access Journals (Sweden)

    Lisha Yang

    Full Text Available This study examined the effect of 5 ns electric pulses on macroscopic ionic currents in whole-cell voltage-clamped adrenal chromaffin cells. Current-voltage (I-V relationships first established that the early peak inward current was primarily composed of a fast voltage-dependent Na+ current (INa, whereas the late outward current was composed of at least three ionic currents: a voltage-gated Ca2+ current (ICa, a Ca2+-activated K+ current (IK(Ca, and a sustained voltage-dependent delayed rectifier K+ current (IKV. A constant-voltage step protocol was next used to monitor peak inward and late outward currents before and after cell exposure to a 5 ns pulse. A single pulse applied at an electric (E-field amplitude of 5 MV/m resulted in an instantaneous decrease of ~4% in peak INa that then declined exponentially to a level that was ~85% of the initial level after 10 min. Increasing the E-field amplitude to 8 or 10 MV/m caused a twofold greater inhibitory effect on peak INa. The decrease in INa was not due to a change in either the steady-state inactivation or activation of the Na+ channel but instead was associated with a decrease in maximal Na+ conductance. Late outward current was not affected by a pulse applied at 5 MV/m. However, for a pulse applied at the higher E-field amplitudes of 8 and 10 MV/m, late outward current in some cells underwent a progressive ~22% decline over the course of the first 20 s following pulse exposure, with no further decline. The effect was most likely concentrated on ICa and IK(Ca as IKV was not affected. The results of this study indicate that in whole-cell patch clamped adrenal chromaffin cells, a 5 ns pulse differentially inhibits specific voltage-gated ionic currents in a manner that can be manipulated by tuning E-field amplitude.

  14. Negligible substrate clamping effect on piezoelectric response in (111)-epitaxial tetragonal Pb(Zr, Ti)O3 films

    International Nuclear Information System (INIS)

    Yamada, Tomoaki; Yasumoto, Jun; Ito, Daisuke; Yoshino, Masahito; Nagasaki, Takanori; Sakata, Osami; Imai, Yasuhiko; Kiguchi, Takanori; Shiraishi, Takahisa; Shimizu, Takao; Funakubo, Hiroshi

    2015-01-01

    The converse piezoelectric responses of (111)- and (001)-epitaxial tetragonal Pb(Zr 0.35 Ti 0.65 )O 3 [PZT] films were compared to investigate the orientation dependence of the substrate clamping effect. Synchrotron X-ray diffraction (XRD) and piezoelectric force microscopy revealed that the as-grown (111)-PZT film has a polydomain structure with normal twin boundaries that are changed by the poling process to inclined boundaries, as predicted by Romanov et al. [Phys. Status Solidi A 172, 225 (1999)]. Time-resolved synchrotron XRD under bias voltage showed the negligible impact of substrate clamping on the piezoelectric response in the (111)-PZT film, unlike the case for (001)-PZT film. The origin of the negligible clamping effect in the (111)-PZT film is discussed from the viewpoint of the elastic properties and the compensation of lattice distortion between neighboring domains

  15. Loading dynamics of a sliding DNA clamp.

    KAUST Repository

    Cho, Won-Ki

    2014-05-22

    Sliding DNA clamps are loaded at a ss/dsDNA junction by a clamp loader that depends on ATP binding for clamp opening. Sequential ATP hydrolysis results in closure of the clamp so that it completely encircles and diffuses on dsDNA. We followed events during loading of an E. coli β clamp in real time by using single-molecule FRET (smFRET). Three successive FRET states were retained for 0.3 s, 0.7 s, and 9 min: Hydrolysis of the first ATP molecule by the γ clamp loader resulted in closure of the clamp in 0.3 s, and after 0.7 s in the closed conformation, the clamp was released to diffuse on the dsDNA for at least 9 min. An additional single-molecule polarization study revealed that the interfacial domain of the clamp rotated in plane by approximately 8° during clamp closure. The single-molecule polarization and FRET studies thus revealed the real-time dynamics of the ATP-hydrolysis-dependent 3D conformational change of the β clamp during loading at a ss/dsDNA junction.

  16. Early identification of hERG liability in drug discovery programs by automated patch clamp

    Directory of Open Access Journals (Sweden)

    Timm eDanker

    2014-09-01

    Full Text Available Blockade of the cardiac ion channel coded by hERG can lead to cardiac arrhythmia, which has become a major concern in drug discovery and development. Automated electrophysiological patch clamp allows assessment of hERG channel effects early in drug development to aid medicinal chemistry programs and has become routine in pharmaceutical companies. However, a number of potential sources of errors in setting up hERG channel assays by automated patch clamp can lead to misinterpretation of data or false effects being reported. This article describes protocols for automated electrophysiology screening of compound effects on the hERG channel current. Protocol details and the translation of criteria known from manual patch clamp experiments to automated patch clamp experiments to achieve good quality data are emphasized. Typical pitfalls and artifacts that may lead to misinterpretation of data are discussed. While this article focuses on hERG channel recordings using the QPatch (Sophion A/S, Copenhagen, Denmark technology, many of the assay and protocol details given in this article can be transferred for setting up different ion channel assays by automated patch clamp and are similar on other planar patch clamp platforms.

  17. Effects of Voltage-Gated K+ Channel on Cell Proliferation in Multiple Myeloma

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2014-01-01

    Full Text Available Objective. To study the effects and underlying mechanisms of voltage-gated K+ channels on the proliferation of multiple myeloma cells. Methods. RPMI-8226 MM cell line was used for the experiments. Voltage-gated K+ currents and the resting potential were recorded by whole-cell patch-clamp technique. RT-PCR detected Kv channel mRNA expression. Cell viability was analyzed with MTT assay. Cell counting system was employed to monitor cell proliferation. DNA contents and cell volume were analyzed by flow cytometry. Results. Currents recorded in RPMI-8226 cells were confirmed to be voltage-gated K+ channels. A high level of Kv1.3 mRNA was detected but no Kv3.1 mRNA was detected in RPMI-8226 cells. Voltage-gated K+ channel blocker 4-aminopyridine (4-AP (2 mM depolarized the resting potential from −42 ± 1.7 mV to −31.8 ± 2.8 mV (P0.05. Conclusions. In RPMI-8226, voltage-gated K+ channels are involved in proliferation and cell cycle progression its influence on the resting potential and cell volume may be responsible for this process; the inhibitory effect of the voltage-gated K+ channel blocker on RPMI-8226 cell proliferation is a phase-specific event.

  18. An equivalent network representation of a clamped bimorph piezoelectric micromachined ultrasonic transducer with circular and annular electrodes using matrix manipulation techniques.

    Science.gov (United States)

    Sammoura, Firas; Smyth, Katherine; Kim, Sang-Gook

    2013-09-01

    An electric circuit model for a clamped circular bimorph piezoelectric micromachined ultrasonic transducer (pMUT) was developed for the first time. The pMUT consisted of two piezoelectric layers sandwiched between three thin electrodes. The top and bottom electrodes were separated into central and annular electrodes by a small gap. While the middle electrode was grounded, the central and annular electrodes were biased with two independent voltage sources. The strain mismatch between the piezoelectric layers caused the plate to vibrate and transmit a pressure wave, whereas the received echo generated electric charges resulting from plate deformation. The clamped pMUT plate was separated into a circular and an annular plate, and the respective electromechanical transformation matrices were derived. The force and velocity vectors were properly selected using Hamilton's principle and the necessary boundary conditions were invoked. The electromechanical transformation matrix for the clamped circular pMUT was deduced using simple matrix manipulation techniques. The pMUT performance under three biasing schemes was elaborated: 1) central electrode only, 2) central and annular electrodes with voltages of the same magnitude and polarity, and 3) central and annular electrodes with voltages of the same magnitude and opposite polarity. The circuit parameters of the pMUT were extracted for each biasing scheme, including the transformer ratio, the clamped electric impedance, and the open-circuit mechanical impedance. Each pMUT scheme was characterized under different acoustic loadings using the theoretically developed model, which was verified with finite element modeling (FEM) simulation. The electrode size was optimized to maximize the electromechanical transformer ratio. As such, the developed model could provide more insight into the design, optimization, and characterization of pMUTs and allow for performance comparison with their cMUT counterparts.

  19. A complete dc characterization of a constant-frequency, clamped-mode, series-resonant converter

    Science.gov (United States)

    Tsai, Fu-Sheng; Lee, Fred C.

    1988-01-01

    The dc behavior of a clamped-mode series-resonant converter is characterized systematically. Given a circuit operating condition, the converter's mode of operation is determined and various circuit parameters are calculated, such as average inductor current (load current), rms inductor current, peak capacitor voltage, rms switch currents, average diode currents, switch turn-on currents, and switch turn-off currents. Regions of operation are defined, and various circuit characteristics are derived to facilitate the converter design.

  20. A self-strain feedback tuning-fork-shaped ionic polymer metal composite clamping actuator with soft matter elasticity-detecting capability for biomedical applications.

    Science.gov (United States)

    Feng, Guo-Hua; Huang, Wei-Lun

    2014-12-01

    This paper presents a smart tuning-fork-shaped ionic polymer metal composite (IPMC) clamping actuator for biomedical applications. The two fingers of the actuator, which perform the clamping motion, can be electrically controlled through a unique electrode design on the IPMC material. The generated displacement or strain of the fingers can be sensed using an integrated soft strain-gage sensor. The IPMC actuator and associated soft strain gage were fabricated using a micromachining technique. A 13.5×4×2 mm(3) actuator was shaped from Nafion solution and a selectively grown metal electrode formed the active region. The strain gage consisted of patterned copper foil and polyethylene as a substrate. The relationship between the strain gage voltage output and the displacement at the front end of the actuator's fingers was characterized. The equivalent Young's modulus, 13.65 MPa, of the soft-strain-gage-integrated IPMC finger was analyzed. The produced clamping force exhibited a linear increasing rate of 1.07 mN/s, based on a dc driving voltage of 7 V. Using the developed actuator to clamp soft matter and simultaneously acquire its Young's modulus was achieved. This demonstrated the feasibility of the palpation function and the potential use of the actuator in minimally invasive surgery. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Harmonic elimination in diode-clamped multilevel inverter using evolutionary algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Barkati, Said [Laboratoire d' analyse des Signaux et Systemes (LASS), Universite de M' sila, BP. 166, rue Ichbilia 28000 M' sila (Algeria); Baghli, Lotfi [Groupe de Recherche en Electrotechnique et Electronique de Nancy (GREEN), CNRS UMR 7030, Universite Henri Poincare Nancy 1, BP. 239, 54506 Vandoeuvre-les-Nancy (France); Berkouk, El Madjid; Boucherit, Mohamed-Seghir [Laboratoire de Commande des Processus (LCP), Ecole Nationale Polytechnique, BP. 182, 10 Avenue Hassen Badi, 16200 El Harrach, Alger (Algeria)

    2008-10-15

    This paper describes two evolutionary algorithms for the optimized harmonic stepped-waveform technique. Genetic algorithms and particle swarm optimization are applied to compute the switching angles in a three-phase seven-level inverter to produce the required fundamental voltage while, at the same time, specified harmonics are eliminated. Furthermore, these algorithms are also used to solve the starting point problem of the Newton-Raphson conventional method. This combination provides a very effective method for the harmonic elimination technique. This strategy is useful for different structures of seven-level inverters. The diode-clamped topology is considered in this study. (author)

  2. Analysis of the role of PCNA-DNA contacts during clamp loading

    Directory of Open Access Journals (Sweden)

    Goedken Eric R

    2010-01-01

    Full Text Available Abstract Background Sliding clamps, such as Proliferating Cell Nuclear Antigen (PCNA in eukaryotes, are ring-shaped protein complexes that encircle DNA and enable highly processive DNA replication by serving as docking sites for DNA polymerases. In an ATP-dependent reaction, clamp loader complexes, such as the Replication Factor-C (RFC complex in eukaryotes, open the clamp and load it around primer-template DNA. Results We built a model of RFC bound to PCNA and DNA based on existing crystal structures of clamp loaders. This model suggests that DNA would enter the clamp at an angle during clamp loading, thereby interacting with positively charged residues in the center of PCNA. We show that simultaneous mutation of Lys 20, Lys 77, Arg 80, and Arg 149, which interact with DNA in the RFC-PCNA-DNA model, compromises the ability of yeast PCNA to stimulate the DNA-dependent ATPase activity of RFC when the DNA is long enough to extend through the clamp. Fluorescence anisotropy binding experiments show that the inability of the mutant clamp proteins to stimulate RFC ATPase activity is likely caused by reduction in the affinity of the RFC-PCNA complex for DNA. We obtained several crystal forms of yeast PCNA-DNA complexes, measuring X-ray diffraction data to 3.0 Å resolution for one such complex. The resulting electron density maps show that DNA is bound in a tilted orientation relative to PCNA, but makes different contacts than those implicated in clamp loading. Because of apparent partial disorder in the DNA, we restricted refinement of the DNA to a rigid body model. This result contrasts with previous analysis of a bacterial clamp bound to DNA, where the DNA was well resolved. Conclusion Mutational analysis of PCNA suggests that positively charged residues in the center of the clamp create a binding surface that makes contact with DNA. Disruption of this positive surface, which had not previously been implicated in clamp loading function, reduces RFC

  3. Negligible substrate clamping effect on piezoelectric response in (111)-epitaxial tetragonal Pb(Zr, Ti)O{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Tomoaki, E-mail: t-yamada@nucl.nagoya-u.ac.jp [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Yasumoto, Jun; Ito, Daisuke; Yoshino, Masahito; Nagasaki, Takanori [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Sakata, Osami [Synchrotron X-ray Station at SPring-8 and Synchrotron X-ray Group, National Institute for Materials Science, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Department of Innovative and Engineered Material, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Imai, Yasuhiko [Japan Synchrotron Radiation Research Institute, SPring-8, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kiguchi, Takanori [Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Shiraishi, Takahisa; Shimizu, Takao; Funakubo, Hiroshi [Department of Innovative and Engineered Material, Tokyo Institute of Technology, Yokohama 226-8503 (Japan)

    2015-08-21

    The converse piezoelectric responses of (111)- and (001)-epitaxial tetragonal Pb(Zr{sub 0.35}Ti{sub 0.65})O{sub 3} [PZT] films were compared to investigate the orientation dependence of the substrate clamping effect. Synchrotron X-ray diffraction (XRD) and piezoelectric force microscopy revealed that the as-grown (111)-PZT film has a polydomain structure with normal twin boundaries that are changed by the poling process to inclined boundaries, as predicted by Romanov et al. [Phys. Status Solidi A 172, 225 (1999)]. Time-resolved synchrotron XRD under bias voltage showed the negligible impact of substrate clamping on the piezoelectric response in the (111)-PZT film, unlike the case for (001)-PZT film. The origin of the negligible clamping effect in the (111)-PZT film is discussed from the viewpoint of the elastic properties and the compensation of lattice distortion between neighboring domains.

  4. Research on micromanipulator’s clamping force sensing based on static wirerope tension of a surgical robot

    Directory of Open Access Journals (Sweden)

    Lingtao Yu

    2015-04-01

    Full Text Available The micromanipulator’s force feedback is one of the key research contents of minimally invasive surgical robotic system. Because the micromanipulator is a kind of compact construction which is suitable for valve installation with small space in surgery, especially for the influence of disinfection method, there are major difficulties and limitations to integrate compact sensors in the end of micromanipulator. This article focuses on the 3-degree-of-freedom micromanipulator’s clamping force sensing, and these three joints are actuated by wirerope driving. A clamping force sensing method is proposed based on static tension of wirerope driving, and a static model between the clamping force and wirerope’s static tension is established considering the influence of real friction resistance in the mechanical system. Finally, an equivalent experimental test platform for 3-degree-of-freedom micromanipulator’s clamping force sensing is set up, and then a series of experiments of the clamping force are studied. The frictional resistances of wirerope between the guide plate and guide pulley mechanism are tested, and a calibration and correction method of the experimental clamping force is proposed. The final experiment results show that the total average accuracy of experimental clamping force is about 78.3%, and it can be the basic measurement force to realize micromanipulator’s clamping force feedback of a minimally invasive surgical robot.

  5. Pipe clamp effects on thin-walled pipe design

    International Nuclear Information System (INIS)

    Lindquist, M.R.

    1980-01-01

    Clamp induced stresses in FFTF piping are sufficiently large to require structural assessment. The basic principles and procedures used in analyzing FFTF piping at clamp support locations for compliance with ASME Code rules are given. Typical results from a three-dimensional shell finite element pipe model with clamp loads applied over the clamp/pipe contact area are shown. Analyses performed to categorize clamp induced piping loads as primary or secondary in nature are described. The ELCLAMP Computer Code, which performs analyses at clamp locations combining clamp induced stresses with stresses from overall piping system loads, is discussed. Grouping and enveloping methods to reduce the number of individual clamp locations requiring analysis are described

  6. Summary of transient high-voltage calculations for the FRX-C experiment

    International Nuclear Information System (INIS)

    Kewish, R.W. Jr.; Rej, D.J.

    1982-06-01

    Calculations of the electrical circuit equations are performed over a wide range of parameters corresponding to the FRX-C field-reversed THETA-pinch experiment at Los Alamos. Without any plasma or external damping, serious voltage doubling and quadrupling of the main capacitor bank charge voltage are observed. These oscillating high voltages are found to be adequately suppressed by the strategic placement of external snubber circuitry. On the other hand, no doubling of the THETA-pinch preionization bank charge voltage is found. Calculations of the equations for the z-pinch preionization circuit are also performed

  7. Ion channel electrophysiology via integrated planar patch-clamp chip with on-demand drug exchange.

    Science.gov (United States)

    Chen, Chang-Yu; Tu, Ting-Yuan; Jong, De-Shien; Wo, Andrew M

    2011-06-01

    Planar patch clamp has revolutionized characterization of ion channel behavior in drug discovery primarily via advancement in high throughput. Lab use of planar technology, however, addresses different requirements and suffers from inflexibility to enable wide range of interrogation via a single cell. This work presents integration of planar patch clamp with microfluidics, achieving multiple solution exchanges for tailor-specific measurement and allowing rapid replacement of the cell-contacting aperture. Studies via endogenously expressed ion channels in HEK 293T cells were commenced to characterize the device. Results reveal the microfluidic concentration generator produces distinct solution/drug combination/concentrations on-demand. Volume-regulated chloride channel and voltage-gated potassium channels in HEK 293T cells immersed in generated solutions under various osmolarities or drug concentrations show unique channel signature under specific condition. Excitation and blockage of ion channels in a single cell was demonstrated via serial solution exchange. Robustness of the reversible bonding and ease of glass substrate replacement were proven via repeated usage of the integrated device. The present approach reveals the capability and flexibility of integrated microfluidic planar patch-clamp system for ion channel assays. Copyright © 2011 Wiley Periodicals, Inc.

  8. Multifrequency Excitation of a Clamped-Clamped Microbeam

    KAUST Repository

    Jaber, Nizar R.

    2016-01-20

    We present analytical and experimental investigation of an electrically actuated clamped-clamped microbeam under a twosource harmonic excitation. The first frequency is swept around the first mode of vibration where the second one is fixed. These microbeams are fabricated using polyimide as structural layer coated with nickel form top and chromium and gold layers from bottom. We demonstrate the excitation of additive and subtractive type resonance. We show that by properly tuning the frequency and the amplitude of the excitation force, the frequency bandwidth of the resonator is increased. Theoretically, we solved the eigenvalue problem for different axial forces to find the natural frequencies ratio that match the experimental values. Using Galerkin method, a reduced order model is derived to simulate the static and dynamic response of the device where using three symmetric mode shapes provided a good agreement with experimental data. © Copyright 2015 by ASME.

  9. Applicability of fiber model in seismic response analysis for center-clamp type bushings on transformers

    International Nuclear Information System (INIS)

    Miyagawa, Yoshinori; Sato, Hiroaki

    2015-01-01

    A bushing is a device for insulation and support of a conductor. Especially it is called center-clamp type when it is connected with a metal holder through clamping force. As a consequence of damage of center-clamp type bushings in Tohoku Earthquake in 2011, refinement of the response analysis method and review of the seismic design procedure became necessary. In the present report, the fiber model, which can evaluate non-linear behavior in the section subjected to axial force and bending moment, was implemented to the CRIEPI's finite element analysis program 'Mastrd' considering following characteristics of center-clamp type bushings. a) The gasket section between a porcelain tube and a metal holder has a torus shape. b) Springs around the top of the bushing give clamping force, but they lock in excessive base rotation. c) The gasket does not resist against tension. d) Local resistance against compression due to bending increases in use of very thin gaskets. The developed program was verified through comparison with the shaking table test result for real bushings whose voltage classes were 154 kV and 275 kV. Deformation indices as rotation angle and base opening due to bending were influenced by damping conditions. Though there was not the condition which brought about remarkable underestimation, reduction of damping for a fiber model element was preferable for safety. On the other hand, bending moment was consistent with experimental results because it tended not to fluctuate in the non-linear region. (author)

  10. Photocontrol of Voltage-Gated Ion Channel Activity by Azobenzene Trimethylammonium Bromide in Neonatal Rat Cardiomyocytes.

    Directory of Open Access Journals (Sweden)

    Sheyda R Frolova

    Full Text Available The ability of azobenzene trimethylammonium bromide (azoTAB to sensitize cardiac tissue excitability to light was recently reported. The dark, thermally relaxed trans- isomer of azoTAB suppressed spontaneous activity and excitation propagation speed, whereas the cis- isomer had no detectable effect on the electrical properties of cardiomyocyte monolayers. As the membrane potential of cardiac cells is mainly controlled by activity of voltage-gated ion channels, this study examined whether the sensitization effect of azoTAB was exerted primarily via the modulation of voltage-gated ion channel activity. The effects of trans- and cis- isomers of azoTAB on voltage-dependent sodium (INav, calcium (ICav, and potassium (IKv currents in isolated neonatal rat cardiomyocytes were investigated using the whole-cell patch-clamp technique. The experiments showed that azoTAB modulated ion currents, causing suppression of sodium (Na+ and calcium (Ca2+ currents and potentiation of net potassium (K+ currents. This finding confirms that azoTAB-effect on cardiac tissue excitability do indeed result from modulation of voltage-gated ion channels responsible for action potential.

  11. A new mechanism of voltage-dependent gating exposed by KV10.1 channels interrupted between voltage sensor and pore.

    Science.gov (United States)

    Tomczak, Adam P; Fernández-Trillo, Jorge; Bharill, Shashank; Papp, Ferenc; Panyi, Gyorgy; Stühmer, Walter; Isacoff, Ehud Y; Pardo, Luis A

    2017-05-01

    Voltage-gated ion channels couple transmembrane potential changes to ion flow. Conformational changes in the voltage-sensing domain (VSD) of the channel are thought to be transmitted to the pore domain (PD) through an α-helical linker between them (S4-S5 linker). However, our recent work on channels disrupted in the S4-S5 linker has challenged this interpretation for the KCNH family. Furthermore, a recent single-particle cryo-electron microscopy structure of K V 10.1 revealed that the S4-S5 linker is a short loop in this KCNH family member, confirming the need for an alternative gating model. Here we use "split" channels made by expression of VSD and PD as separate fragments to investigate the mechanism of gating in K V 10.1. We find that disruption of the covalent connection within the S4 helix compromises the ability of channels to close at negative voltage, whereas disconnecting the S4-S5 linker from S5 slows down activation and deactivation kinetics. Surprisingly, voltage-clamp fluorometry and MTS accessibility assays show that the motion of the S4 voltage sensor is virtually unaffected when VSD and PD are not covalently bound. Finally, experiments using constitutively open PD mutants suggest that the presence of the VSD is structurally important for the conducting conformation of the pore. Collectively, our observations offer partial support to the gating model that assumes that an inward motion of the C-terminal S4 helix, rather than the S4-S5 linker, closes the channel gate, while also suggesting that control of the pore by the voltage sensor involves more than one mechanism. © 2017 Tomczak et al.

  12. Trans-Z-source Neutral Point Clamped inverter

    DEFF Research Database (Denmark)

    Mo, W.; Loh, P. C.; Li, D.

    2012-01-01

    Transformer based Z-source (trans-Z-source) inverters are recently proposed by extending the traditional Z-source inverter with higher buck-boost capability as well as reducing the passive components at the same time. Multi-Level Z-source inverters are single-stage topological solutions used...... for buck-boost energy conversion with all the favourable advantages of multi-level switching retained. This paper presents three-level trans-Z-source Neutral Point Clamped (NPC) inverter topology, which achieves both the advantages of trans-Z-source and three-level NPC inverter configuration. With proper...... modulation scheme, the three-level trans-Z-source inverter can function with minimum of six device commutations per half carrier cycle (same as the traditional buck NPC inverter), while maintaining to produce the designed volt-sec average and inductive voltage boosting at ac output terminals. The designed...

  13. High voltage bus and auxiliary heater control system for an electric or hybrid vehicle

    Science.gov (United States)

    Murty, Balarama Vempaty

    2000-01-01

    A control system for an electric or hybrid electric vehicle includes a vehicle system controller and a control circuit having an electric immersion heater. The heater is electrically connected to the vehicle's high voltage bus and is thermally coupled to a coolant loop containing a heater core for the vehicle's climate control system. The system controller responds to cabin heat requests from the climate control system by generating a pulse width modulated signal that is used by the control circuit to operate the heater at a duty cycle appropriate for the amount of cabin heating requested. The control system also uses the heater to dissipate excess energy produced by an auxiliary power unit and to provide electric braking when regenerative braking is not desirable and manual braking is not necessary. The control system further utilizes the heater to provide a safe discharge of a bank of energy storage capacitors following disconnection of the battery or one of the high voltage connectors used to transmit high voltage operating power to the various vehicle systems. The control circuit includes a high voltage clamping circuit that monitors the voltage on the bus and operates the heater to clamp down the bus voltage when it exceeds a pre-selected maximum voltage. The control system can also be used to phase in operation of the heater when the bus voltage exceeds a lower threshold voltage and can be used to phase out the auxiliary power unit charging and regenerative braking when the battery becomes fully charged.

  14. Dynamics of a clamped–clamped microbeam resonator considering fabrication imperfections

    KAUST Repository

    Bataineh, Ahmad M.

    2014-10-18

    We present an investigation into the static and dynamic behavior of an electrostatically actuated clamped–clamped polysilicon microbeam resonator accounting for its fabrication imperfections, which are commonly encountered in similar microstructures. These are mainly because of the initial deformation of the beam due to stress gradient and its flexible anchors. First, we show experimental data of the microbeam when driven electrically by varying the amplitude and frequency of the voltage loads. The results reveal several interesting nonlinear phenomena of jumps, hysteresis, and softening behaviors. Theoretical investigation is then conducted to model the microbeam, and hence, interpret the experimental data. We solve the Eigen value problem governing the natural frequencies analytically. We then utilize a Galerkin-based procedure to derive a reduced order model, which is then used to simulate both the static and dynamic responses. To achieve good matching between theory and experiment, we show that the exact profile of the deformed beam needs to be utilized in the reduced order model, as measured from the optical profiler, combined with a shooting technique simulation, which is capable of tracing the resonant frequency branches under very-low damping conditions.

  15. Design and Implementation of a High Efficiency, Low Component Voltage Stress, Single-Switch High Step-Up Voltage Converter for Vehicular Green Energy Systems

    Directory of Open Access Journals (Sweden)

    Yu-En Wu

    2016-09-01

    Full Text Available In this study, a novel, non-isolated, cascade-type, single-switch, high step-up DC/DC converter was developed for green energy systems. An integrated coupled inductor and voltage lift circuit were applied to simplify the converter structure and satisfy the requirements of high efficiency and high voltage gain ratios. In addition, the proposed structure is controllable with a single switch, which effectively reduces the circuit cost and simplifies the control circuit. With the leakage inductor energy recovery function and active voltage clamp characteristics being present, the circuit yields optimizable conversion efficiency and low component voltage stress. After the operating principles of the proposed structure and characteristics of a steady-state circuit were analyzed, a converter prototype with 450 W, 40 V of input voltage, 400 V of output voltage, and 95% operating efficiency was fabricated. The Renesas MCU RX62T was employed to control the circuits. Experimental results were analyzed to validate the feasibility and effectiveness of the proposed system.

  16. 4-Aminopyridine: a pan voltage-gated potassium channel inhibitor that enhances K7.4 currents and inhibits noradrenaline-mediated contraction of rat mesenteric small arteries

    DEFF Research Database (Denmark)

    Khammy, Makhala M; Kim, Sukhan; Bentzen, Bo H

    2018-01-01

    has not been systematically studied. The aim of this study was to investigate the pharmacological activity of 4-AP on Kv7.4 and Kv7.5 channels and characterize the effect of 4-AP on rat resistance arteries. EXPERIMENTAL APPROACH: Voltage clamp experiments were performed on Xenopus laevis oocytes......BACKGROUND AND PURPOSE: Kv7.4 and Kv7.5 channels are regulators of vascular tone. 4-Aminopyridine (4-AP) is considered a broad inhibitor of voltage-gated potassium (KV) channels, with little inhibitory effect on Kv7 family members at mmol concentrations. However, the effect of 4-AP on Kv7 channels...

  17. The NH2 terminus regulates voltage-dependent gating of CALHM ion channels.

    Science.gov (United States)

    Tanis, Jessica E; Ma, Zhongming; Foskett, J Kevin

    2017-08-01

    Calcium homeostasis modulator protein-1 (CALHM1) and its Caenorhabditis elegans (ce) homolog, CLHM-1, belong to a new family of physiologically important ion channels that are regulated by voltage and extracellular Ca 2+ (Ca 2+ o ) but lack a canonical voltage-sensing domain. Consequently, the intrinsic voltage-dependent gating mechanisms for CALHM channels are unknown. Here, we performed voltage-clamp experiments on ceCLHM-1 chimeric, deletion, insertion, and point mutants to assess the role of the NH 2 terminus (NT) in CALHM channel gating. Analyses of chimeric channels in which the ceCLHM-1 and human (h)CALHM1 NH 2 termini were interchanged showed that the hCALHM1 NT destabilized channel-closed states, whereas the ceCLHM-1 NT had a stabilizing effect. In the absence of Ca 2+ o , deletion of up to eight amino acids from the ceCLHM-1 NT caused a hyperpolarizing shift in the conductance-voltage relationship with little effect on voltage-dependent slope. However, deletion of nine or more amino acids decreased voltage dependence and induced a residual conductance at hyperpolarized voltages. Insertion of amino acids into the NH 2 -terminal helix also decreased voltage dependence but did not prevent channel closure. Mutation of ceCLHM-1 valine 9 and glutamine 13 altered half-maximal activation and voltage dependence, respectively, in 0 Ca 2+ In 2 mM Ca 2+ o , ceCLHM-1 NH 2 -terminal deletion and point mutant channels closed completely at hyperpolarized voltages with apparent affinity for Ca 2+ o indistinguishable from wild-type ceCLHM-1, although the ceCLHM-1 valine 9 mutant exhibited an altered conductance-voltage relationship and kinetics. We conclude that the NT plays critical roles modulating voltage dependence and stabilizing the closed states of CALHM channels. Copyright © 2017 the American Physiological Society.

  18. Analysis list: Clamp [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Clamp Cell line + dm3 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/Clamp.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/Clam...p.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/Clam...p.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/colo/Clamp.Cell_line.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/colo/Cell_line.gml ...

  19. 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...

  20. Allosteric substrate switching in a voltage-sensing lipid phosphatase.

    Science.gov (United States)

    Grimm, Sasha S; Isacoff, Ehud Y

    2016-04-01

    Allostery provides a critical control over enzyme activity, biasing the catalytic site between inactive and active states. We found that the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP), which modifies phosphoinositide signaling lipids (PIPs), has not one but two sequential active states with distinct substrate specificities, whose occupancy is allosterically controlled by sequential conformations of the voltage-sensing domain (VSD). Using fast fluorescence resonance energy transfer (FRET) reporters of PIPs to monitor enzyme activity and voltage-clamp fluorometry to monitor conformational changes in the VSD, we found that Ci-VSP switches from inactive to a PIP3-preferring active state when the VSD undergoes an initial voltage-sensing motion and then into a second PIP2-preferring active state when the VSD activates fully. This two-step allosteric control over a dual-specificity enzyme enables voltage to shape PIP concentrations in time, and provides a mechanism for the complex modulation of PIP-regulated ion channels, transporters, cell motility, endocytosis and exocytosis.

  1. Allosteric substrate switching in a voltage sensing lipid phosphatase

    Science.gov (United States)

    Grimm, Sasha S.; Isacoff, Ehud Y.

    2016-01-01

    Allostery provides a critical control over enzyme activity, biasing the catalytic site between inactive and active states. We find the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP), which modifies phosphoinositide signaling lipids (PIPs), to have not one but two sequential active states with distinct substrate specificities, whose occupancy is allosterically controlled by sequential conformations of the voltage sensing domain (VSD). Using fast FRET reporters of PIPs to monitor enzyme activity and voltage clamp fluorometry to monitor conformational changes in the VSD, we find that Ci-VSP switches from inactive to a PIP3-preferring active state when the VSD undergoes an initial voltage sensing motion and then into a second PIP2-preferring active state when the VSD activates fully. This novel 2-step allosteric control over a dual specificity enzyme enables voltage to shape PIP concentrations in time, and provides a mechanism for the complex modulation of PIP-regulated ion channels, transporters, cell motility and endo/exocytosis. PMID:26878552

  2. Bingham Sealing and Application in Vacuum Clamping

    Science.gov (United States)

    Yao, S. M.; Teo, Wee Kin; Geng, Zunmin; Turner, Sam; Ridgway, Keith

    2011-12-01

    Vacuum clamping is extensively used in shell machining. In this paper a Bingham Sealing (BS) is presented and formulized based on Bingham plastic performance. The sealing capability of BS is evaluated in various cases. A new Bingham plastic is developed and the yield stress is measured. The performances of "O"ring sealing and BS with the developed Bingham plastic are compared to the static experiment. In this experiment the same vacuum is achieved and the distortion of the blade with BS is better than that with "O" ring sealing.

  3. Bingham Sealing and Application in Vacuum Clamping

    International Nuclear Information System (INIS)

    Yao, S M; Teo, Wee Kin; Geng Zunmin; Turner, Sam; Ridgway, Keith

    2011-01-01

    Vacuum clamping is extensively used in shell machining. In this paper a Bingham Sealing (BS) is presented and formulized based on Bingham plastic performance. The sealing capability of BS is evaluated in various cases. A new Bingham plastic is developed and the yield stress is measured. The performances of Or ing sealing and BS with the developed Bingham plastic are compared to the static experiment. In this experiment the same vacuum is achieved and the distortion of the blade with BS is better than that with 'O' ring sealing.

  4. A patch-clamp ASIC for nanopore-based DNA analysis.

    Science.gov (United States)

    Kim, Jungsuk; Maitra, Raj; Pedrotti, Kenneth D; Dunbar, William B

    2013-06-01

    In this paper, a fully integrated high-sensitivity patch-clamp system is proposed for single-molecule deoxyribonucleic acid (DNA) analysis using a nanopore sensor. This system is composed of two main blocks for amplification and compensation. The amplification block is composed of three stages: 1) a headstage, 2) a voltage-gain difference amplifier, and 3) a track-and-hold circuit, that amplify a minute ionic current variation sensed by the nanopore while the compensation block avoids the headstage saturation caused by the input parasitic capacitances during sensing. By employing design techniques novel for this application, such as an instrumentation--amplifier topology and a compensation switch, we minimize the deleterious effects of the input-offset voltage and the input parasitic capacitances while attaining hardware simplicity. This system is fabricated in a 0.35 μm 4M2P CMOS process and is demonstrated using an α-hemolysin protein nanopore for detection of individual molecules of single-stranded DNA that pass through the 1.5 nm-diameter pore. In future work, the refined system will functionalize single and multiple solid-state nanopores formed in integrated microfluidic devices for advanced DNA analysis, in scientific and diagnostic applications.

  5. Integrated Three-Voltage-Booster DC-DC Converter to Achieve High Voltage Gain with Leakage-Energy Recycling for PV or Fuel-Cell Power Systems

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2015-09-01

    Full Text Available In this paper, an integrated three-voltage-booster DC-DC (direct current to direct current converter is proposed to achieve high voltage gain for renewable-energy generation systems. The proposed converter integrates three voltage-boosters into one power stage, which is composed of an active switch, a coupled-inductor, five diodes, and five capacitors. As compared with conventional high step-up converters, it has a lower component count. In addition, the features of leakage-energy recycling and switching loss reduction can be accomplished for conversion efficiency improvement. While the active switch is turned off, the converter can inherently clamp the voltage across power switch and suppress voltage spikes. Moreover, the reverse-recovery currents of all diodes can be alleviated by leakage inductance. A 200 W prototype operating at 100 kHz switching frequency with 36 V input and 400 V output is implemented to verify the theoretical analysis and to demonstrate the feasibility of the proposed high step-up DC-DC converter.

  6. Analysis of the Pallet Clamping Conditions in Work Positioning

    Directory of Open Access Journals (Sweden)

    L. A. Kolesnikov

    2016-01-01

    Full Text Available Pallets of automatic transfer lines serve as the technological and work-transfer equipment. However, their design is based on the general principles of designing machine accessories. Calculation of the basic design parameters of work based on their functioning features is fairly relevant.In pallet transfer movement over work positioning there is a mismatch between axes of the basic bushing of a pallet and the clamping locks of positioning. The paper identifies the factors influencing it, and defines the conditions to ensure the trouble-free clamping lock. The circular and rhombic clamping of pallet is simultaneous. Further, a clamping load is calculated from the pallet mass (together with the work-piece and the geometric parameters of the pallet clamping.The paper reveals three movement stages of the clamping lock in a vertical plane when setting the pallet in work positioning:- a clamping lock free play till it encounters with the location bushing;- a clamping lock play length when the lead-in chamfer contacts the bushing chamfer;- a clamping lock play length over the circular surface of bushing.The study of this process has allowed us to calculate the time of pallet clamping and dynamic loads acting on the clamping lock. These calculations made it possible to calculate the required diameter of the clamping lock. The presented calculations allow a reasonable assigning the main design parameters of work positioning for the pallet automatic lines.

  7. Ventilation onset prior to umbilical cord clamping (physiological-based cord clamping improves systemic and cerebral oxygenation in preterm lambs.

    Directory of Open Access Journals (Sweden)

    Graeme R Polglase

    Full Text Available As measurement of arterial oxygen saturation (SpO2 is common in the delivery room, target SpO2 ranges allow clinicians to titrate oxygen therapy for preterm infants in order to achieve saturation levels similar to those seen in normal term infants in the first minutes of life. However, the influence of the onset of ventilation and the timing of cord clamping on systemic and cerebral oxygenation is not known.We investigated whether the initiation of ventilation, prior to, or after umbilical cord clamping, altered systemic and cerebral oxygenation in preterm lambs.Systemic and cerebral blood-flows, pressures and peripheral SpO2 and regional cerebral tissue oxygenation (SctO2 were measured continuously in apnoeic preterm lambs (126±1 day gestation. Positive pressure ventilation was initiated either 1 prior to umbilical cord clamping, or 2 after umbilical cord clamping. Lambs were monitored intensively prior to intervention, and for 10 minutes following umbilical cord clamping.Clamping the umbilical cord prior to ventilation resulted in a rapid decrease in SpO2 and SctO2, and an increase in arterial pressure, cerebral blood flow and cerebral oxygen extraction. Ventilation restored oxygenation and haemodynamics by 5-6 minutes. No such disturbances in peripheral or cerebral oxygenation and haemodynamics were observed when ventilation was initiated prior to cord clamping.The establishment of ventilation prior to umbilical cord clamping facilitated a smooth transition to systemic and cerebral oxygenation following birth. SpO2 nomograms may need to be re-evaluated to reflect physiological management of preterm infants in the delivery room.

  8. The cardiovascular effects of aortic clamping and unclamping

    African Journals Online (AJOL)

    aortic clamping is that afterload and blood pressure increase, and ... individually, albeit they interact with each other. The degree of ... position of the aortic clamp, the greater the increase ... the increase in preload in response to aortic clamping.

  9. [The Impact of Late Umbilical Cord Clamping on Neonatal Jaundice and Postpartum Hemorrhage: A Randomized Controlled Trail].

    Science.gov (United States)

    Chien, Pei-Chun; Yang, Cherng-Chia; Gau, Meei-Ling; Liu, Chieh-Yu; Lee, Tzu-Ying

    2015-08-01

    The current evidence supports the clinical benefits of late umbilical cord clamping. These benefits include increased blood volume and total body iron. Furthermore, delayed cord clamping facilitates the transplantation of stem cells, which helps the development of infant bodily systems. However, due to concerns related to postpartum hemorrhaging and neonate jaundice, most maternity units still clamp the cord immediately after a child is born. This study investigates the impact of delaying cord clamping on neonatal jaundice and postpartum hemorrhage. A randomized, controlled trial was conducted at a regional teaching hospital in northern Taiwan. One hundred and five healthy nulliparous women at 36 weeks of pregnancy were included and allocated randomly to the experiment group (n=44) and the control group (n=61). Participants in the experiment group received delayed cord clamping (DCC) at 3 minutes after delivery. Participants in the control group received early cord clamping (ECC) at around 1 minute after delivery. Clinical measures of the outcomes were measured by the infant transcutaneous bilirubin levels (TcB) and postpartum hemorrhage at birth. A structured questionnaire and biophysical measures were used to collect data on participant demographics, obstetrical information, maternal blood loss at birth, neonate weight and TcB level at hospitalization, and whether or not the infant received phototherapy at 4-7 days postpartum. Overall, there was no significant difference between the two groups in terms of neonatal jaundice, maternal hemorrhage at birth, and phototherapy rates at time of hospitalization and at 4-7 days postpartum. The findings of the present study support that late umbilical cord clamping does not increase the risk of maternal postpartum hemorrhaging or neonate jaundice. Thus, we suggest that clinicians inform clients during prenatal classes of the benefits of delayed cord clamping and also use current, evidence-based knowledge to dispel client

  10. 21 CFR 882.4460 - Neurosurgical head holder (skull clamp).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Neurosurgical head holder (skull clamp). 882.4460... holder (skull clamp). (a) Identification. A neurosurgical head holder (skull clamp) is a device used to clamp the patient's skull to hold head and neck in a particular position during surgical procedures. (b...

  11. High-Efficiency Isolated Boost DCDC Converter for High-Power Low-Voltage Fuel-Cell Applications

    DEFF Research Database (Denmark)

    Nymand, Morten; Andersen, Michael A. E.

    2010-01-01

    high winding losses. The analysis of transformer leakage inductance reveals that extremely low leakage inductance can be achieved, allowing stored energy to be dissipated. Power MOSFETs fully rated for repetitive avalanches allow primary-side voltage clamp circuits to be eliminated. The oversizing...

  12. Active gate driver for dv/dt control and active voltage clamping in an IGBT stack

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg

    2005-01-01

    For high voltages converters stacks of IGBTs can be used if the static and dynamic voltage sharing among the IGBTs can be applied. dVCE/dt should also be controlled in order not to damage insulation material. This paper describes theory and measurements of an active gate driver for stacking IGBTs....... For the measurements two series connected standard IGBTs made for hard switching applications are used. Problems are shown and proposals for improvements are given....

  13. Mechanics of wafer bonding: Effect of clamping

    Science.gov (United States)

    Turner, K. T.; Thouless, M. D.; Spearing, S. M.

    2004-01-01

    A mechanics-based model is developed to examine the effects of clamping during wafer bonding processes. The model provides closed-form expressions that relate the initial geometry and elastic properties of the wafers to the final shape of the bonded pair and the strain energy release rate at the interface for two different clamping configurations. The results demonstrate that the curvature of bonded pairs may be controlled through the use of specific clamping arrangements during the bonding process. Furthermore, it is demonstrated that the strain energy release rate depends on the clamping configuration and that using applied loads usually leads to an undesirable increase in the strain energy release rate. The results are discussed in detail and implications for process development and bonding tool design are highlighted.

  14. A novel NaV1.5 voltage sensor mutation associated with severe atrial and ventricular arrhythmias.

    Science.gov (United States)

    Wang, Hong-Gang; Zhu, Wandi; Kanter, Ronald J; Silva, Jonathan R; Honeywell, Christina; Gow, Robert M; Pitt, Geoffrey S

    2016-03-01

    Inherited autosomal dominant mutations in cardiac sodium channels (NaV1.5) cause various arrhythmias, such as long QT syndrome and Brugada syndrome. Although dozens of mutations throughout the protein have been reported, there are few reported mutations within a voltage sensor S4 transmembrane segment and few that are homozygous. Here we report analysis of a novel lidocaine-sensitive recessive mutation, p.R1309H, in the NaV1.5 DIII/S4 voltage sensor in a patient with a complex arrhythmia syndrome. We expressed the wild type or mutant NaV1.5 heterologously for analysis with the patch-clamp and voltage clamp fluorometry (VCF) techniques. p.R1309H depolarized the voltage-dependence of activation, hyperpolarized the voltage-dependence of inactivation, and slowed recovery from inactivation, thereby reducing the channel availability at physiologic membrane potentials. Additionally, p.R1309H increased the "late" Na(+) current. The location of the mutation in DIIIS4 prompted testing for a gating pore current. We observed an inward current at hyperpolarizing voltages that likely exacerbates the loss-of-function defects at resting membrane potentials. Lidocaine reduced the gating pore current. The p.R1309H homozygous NaV1.5 mutation conferred both gain-of-function and loss-of-function effects on NaV1.5 channel activity. Reduction of a mutation-induced gating pore current by lidocaine suggested a therapeutic mechanism. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Evaluation of clamp effects on LMFBR piping systems

    International Nuclear Information System (INIS)

    Jones, G.L.

    1980-01-01

    Loop-type liquid metal breeder reactor plants utilize thin-wall piping to mitigate through-wall thermal gradients due to rapid thermal transients. These piping loops require a support system to carry the combined weight of the pipe, coolant and insulation and to provide attachments for seismic restraints. The support system examined here utilizes an insulated pipe clamp designed to minimize the stresses induced in the piping. To determine the effect of these clamps on the pipe wall a non-linear, two-dimensional, finite element model of the clamp, insulation and pipe wall was used to determine the clamp/pipe interface load distributions which were then applied to a three-dimensional, finite element model of the pipe. The two-dimensional interaction model was also utilized to estimate the combined clamp/pipe stiffness

  16. Load-deflection characteristics of small-bore insulated-pipe clamps

    International Nuclear Information System (INIS)

    Severud, L.K.; Clark, G.L.

    1981-12-01

    The special insulated clamps used on both FFTF and CRBR piping utilize a Belleville spring arrangement to compensate for pipe thermal expansion. Analysis indicates that this produces a non-linear, directionally sensitive clamp spring rate. Since these spring rates influence the seismic response of a supported piping system, it was deemed necessary to evaluate them further by test. This has been accomplished for the FFTF clamps. A more standard insulated pipe clamp, which does not incorporate Belleville springs to accommodate thermal expansion, was also tested. This type clamp is simple in design, and economically attractive. It may have wide application prospects for use in LMFBR small bore auxiliary piping operating at temperatures below 427 0 C. Load deflection tests were conducted on 2.54 CM and 7.62 CM diameter samples of these commercial clamps

  17. Distribution of voltage-dependent and intracellular Ca2+ channels in submucosal neurons from rat distal colon.

    Science.gov (United States)

    Rehn, Matthias; Bader, Sandra; Bell, Anna; Diener, Martin

    2013-09-01

    We recently observed a bradykinin-induced increase in the cytosolic Ca2+ concentration in submucosal neurons of rat colon, an increase inhibited by blockers of voltage-dependent Ca2+ (Ca(v)) channels. As the types of Ca(v) channels used by this part of the enteric nervous system are unknown, the expression of various Ca(v) subunits has been investigated in whole-mount submucosal preparations by immunohistochemistry. Submucosal neurons, identified by a neuronal marker (microtubule-associated protein 2), are immunoreactive for Ca(v)1.2, Ca(v)1.3 and Ca(v)2.2, expression being confirmed by reverse transcription plus the polymerase chain reaction. These data agree with previous observations that the inhibition of L- and N-type Ca2+ currents strongly inhibits the response to bradykinin. However, whole-cell patch-clamp experiments have revealed that bradykinin does not enhance Ca2+ inward currents under voltage-clamp conditions. Consequently, bradykinin does not directly interact with Ca(v) channels. Instead, the kinin-induced Ca2+ influx is caused indirectly by the membrane depolarization evoked by this peptide. As intracellular Ca2+ channels on Ca(2+)-storing organelles can also contribute to Ca2+ signaling, their expression has been investigated by imaging experiments and immunohistochemistry. Inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) have been functionally demonstrated in submucosal neurons loaded with the Ca(2+)-sensitive fluorescent dye, fura-2. Histamine, a typical agonist coupled to the phospholipase C pathway, induces an increase in the fura-2 signal ratio, which is suppressed by 2-aminophenylborate, a blocker of IP3 receptors. The expression of IP3R1 has been confirmed by immunohistochemistry. In contrast, ryanodine, tested over a wide concentration range, evokes no increase in the cytosolic Ca2+ concentration nor is there immunohistochemical evidence for the expression of ryanodine receptors in these neurons. Thus, rat submucosal neurons are equipped

  18. Depolarization of the conductance-voltage relationship in the NaV1.5 mutant, E1784K, is due to altered fast inactivation

    Science.gov (United States)

    Yu, Alec; Zhu, Wandi; Silva, Jonathan R.; Ruben, Peter C.

    2017-01-01

    E1784K is the most common mixed long QT syndrome/Brugada syndrome mutant in the cardiac voltage-gated sodium channel NaV1.5. E1784K shifts the midpoint of the channel conductance-voltage relationship to more depolarized membrane potentials and accelerates the rate of channel fast inactivation. The depolarizing shift in the midpoint of the conductance curve in E1784K is exacerbated by low extracellular pH. We tested whether the E1784K mutant shifts the channel conductance curve to more depolarized membrane potentials by affecting the channel voltage-sensors. We measured ionic currents and gating currents at pH 7.4 and pH 6.0 in Xenopus laevis oocytes. Contrary to our expectation, the movement of gating charges is shifted to more hyperpolarized membrane potentials by E1784K. Voltage-clamp fluorimetry experiments show that this gating charge shift is due to the movement of the DIVS4 voltage-sensor being shifted to more hyperpolarized membrane potentials. Using a model and experiments on fast inactivation-deficient channels, we show that changes to the rate and voltage-dependence of fast inactivation are sufficient to shift the conductance curve in E1784K. Our results localize the effects of E1784K to DIVS4, and provide novel insight into the role of the DIV-VSD in regulating the voltage-dependencies of activation and fast inactivation. PMID:28898267

  19. Depolarization of the conductance-voltage relationship in the NaV1.5 mutant, E1784K, is due to altered fast inactivation.

    Directory of Open Access Journals (Sweden)

    Colin H Peters

    Full Text Available E1784K is the most common mixed long QT syndrome/Brugada syndrome mutant in the cardiac voltage-gated sodium channel NaV1.5. E1784K shifts the midpoint of the channel conductance-voltage relationship to more depolarized membrane potentials and accelerates the rate of channel fast inactivation. The depolarizing shift in the midpoint of the conductance curve in E1784K is exacerbated by low extracellular pH. We tested whether the E1784K mutant shifts the channel conductance curve to more depolarized membrane potentials by affecting the channel voltage-sensors. We measured ionic currents and gating currents at pH 7.4 and pH 6.0 in Xenopus laevis oocytes. Contrary to our expectation, the movement of gating charges is shifted to more hyperpolarized membrane potentials by E1784K. Voltage-clamp fluorimetry experiments show that this gating charge shift is due to the movement of the DIVS4 voltage-sensor being shifted to more hyperpolarized membrane potentials. Using a model and experiments on fast inactivation-deficient channels, we show that changes to the rate and voltage-dependence of fast inactivation are sufficient to shift the conductance curve in E1784K. Our results localize the effects of E1784K to DIVS4, and provide novel insight into the role of the DIV-VSD in regulating the voltage-dependencies of activation and fast inactivation.

  20. Load-deflection characteristics of small bore insulated pipe clamps

    International Nuclear Information System (INIS)

    Severud, L.K.; Clark, G.L.

    1982-01-01

    High temperature LMFBR piping is subject to rapid temperature changes during transient events. Typically, this pipe is supported by specially designed insulated pipe clamps to prevent excessive thermal stress from developing during these transients. The special insulated clamps used on both FFTF and CRBR piping utilize a Belleville spring arrangement to compensate for pipe thermal expansion. Analysis indicates that this produces a non-linear, directionally sensitive clamp spring rate. Since these spring rates influence the seismic response of a supported piping system, it was deemed necessary to evaluate them further by test. This has been accomplished for the FFTF clamps. A more standard insulated pipe clamp, which does not incorporate Belleville springs to accommodate thermal expansion, was also tested. This type clamp is simple in design, and economically attractive. It may have wide application prospects for use in LMFBR small bore auxiliary piping operating at temperatures below 427 0 C. Load deflection tests were conducted on 2.54 CM and 7.62 CM diameter samples of these commercial clamps

  1. Loading dynamics of a sliding DNA clamp.

    KAUST Repository

    Cho, Won-Ki; Jergic, Slobodan; Kim, Daehyung; Dixon, Nicholas E; Lee, Jong-Bong

    2014-01-01

    8° during clamp closure. The single-molecule polarization and FRET studies thus revealed the real-time dynamics of the ATP-hydrolysis-dependent 3D conformational change of the β clamp during loading at a ss/dsDNA junction.

  2. Membrane voltage changes in passive dendritic trees: a tapering equivalent cylinder model.

    Science.gov (United States)

    Poznański, R R

    1988-01-01

    An exponentially tapering equivalent cylinder model is employed in order to approximate the loss of the dendritic trunk parameter observed from anatomical data on apical and basilar dendrites of CA1 and CA3 hippocampal pyramidal neurons. This model allows dendritic trees with a relative paucity of branching to be treated. In particular, terminal branches are not required to end at the same electrotonic distance. The Laplace transform method is used to obtain analytic expressions for the Green's function corresponding to an instantaneous pulse of current injected at a single point along a tapering equivalent cylinder with sealed ends. The time course of the voltage in response to an arbitrary input is computed using the Green's function in a convolution integral. Examples of current input considered are (1) an infinitesimally brief (Dirac delta function) pulse and (2) a step pulse. It is demonstrated that inputs located on a tapering equivalent cylinder are more effective at the soma than identically placed inputs on a nontapering equivalent cylinder. Asymptotic solutions are derived to enable the voltage response behaviour over both relatively short and long time periods to be analysed. Semilogarithmic plots of these solutions provide a basis for estimating the membrane time constant tau m from experimental transients. Transient voltage decrement from a clamped soma reveals that tapering tends to reduce the error associated with inadequate voltage clamping of the dendritic membrane. A formula is derived which shows that tapering tends to increase the estimate of the electrotonic length parameter L.

  3. Design and experimental research of a novel inchworm type piezo-driven rotary actuator with the changeable clamping radius.

    Science.gov (United States)

    Zhao, Hongwei; Fu, Lu; Ren, Luquan; Huang, Hu; Fan, Zunqiang; Li, Jianping; Qu, Han

    2013-01-01

    In this paper, a novel piezo-driven rotary actuator with the changeable clamping radius is developed based on the inchworm principle. This actuator mainly utilizes three piezoelectric actuators, a flexible gripper, a clamping block, and a rotor to achieve large stroke rotation with high resolution. The design process of the flexible gripper consisting of the driving unit and the clamping unit is described. Lever-type mechanisms were used to amplify the micro clamping displacements. The amplifying factor and parasitic displacement of the lever-type mechanism in the clamping unit was analyzed theoretically and experimentally. In order to investigate the rotation characteristics of the actuator, a series of experiments was carried out. Experimental results indicate that the actuator can rotate at a speed of 77,488 μrad/s with a driving frequency of 167 Hz. The rotation resolution and maximum load torque of the actuator are 0.25 μrad and 37 N mm, respectively. The gripper is movable along the z direction based on an elevating platform, and the clamping radius can change from 10.6 mm to 25 mm. Experimental results confirm that the actuator can achieve different rotation speeds by changing the clamping radius.

  4. A new VME based high voltage power supply for large experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, S.C.; Angstadt, R.D.; Droege, T.F.; Johnson, M.E.; MacKinnon, B.A.; McNulty, S.E.; Shea, M.F.; Thompson, R.N.; Watson, M.M. (Fermi National Accelerator Lab., Batavia, IL (United States)); Franzini, P. (Columbia Univ., New York, NY (United States)); Jones, A.A. (Superconducting Super Collider Lab., Dallas, TX (United States)); Lopez, M.L. (La Plata Univ. Nacional (Argentina)); Wimpenny, S.J.; Yang, M.J

    1991-11-01

    A new VME based high voltage power supply has been developed for the D{O} experiment at Fermilab. There are three types of supplies delivering up to {plus minus}5.6 kV at 1.0 mA or +2.0 kV at 3.0 mA with a set accuracy of 1.5 V and extremely low voltage ripples. Complete computer control has allowed many special features to be developed for the supply, including user-defined control land monitor groups, variable ramp rates, and advanced histogram and graphic functions. 3 refs.

  5. A new VME based high voltage power supply for large experiments

    International Nuclear Information System (INIS)

    Ahn, S.C.; Angstadt, R.D.; Droege, T.F.; Johnson, M.E.; MacKinnon, B.A.; McNulty, S.E.; Shea, M.F.; Thompson, R.N.; Watson, M.M.; Franzini, P.; Jones, A.A.; Lopez, M.L.; Wimpenny, S.J.; Yang, M.J.

    1991-11-01

    A new VME based high voltage power supply has been developed for the D OE experiment at Fermilab. There are three types of supplies delivering up to ±5.6 kV at 1.0 mA or +2.0 kV at 3.0 mA with a set accuracy of 1.5 V and extremely low voltage ripples. Complete computer control has allowed many special features to be developed for the supply, including user-defined control land monitor groups, variable ramp rates, and advanced histogram and graphic functions. 3 refs

  6. Development of a prototype solid state fault current limiting and interrupting device for low voltage distribution networks.

    OpenAIRE

    Ahmed, M.; Putrus, G. A.; Ran, L.; Penlington, R.

    2006-01-01

    This paper describes the development of a solid-state Fault Current Limiting and Interrupting Device (FCLID) suitable for low voltage distribution networks. The main components of the FCLID are a bidirectional semiconductor switch that can disrupt the short-circuit current, and a voltage clamping element that helps in controlling the current and absorbing the inductive energy stored in the network during current interruption. Using a hysteresis type control algorithm, the short-circuit curren...

  7. Core clamping device for a nuclear reactor

    International Nuclear Information System (INIS)

    Guenther, R.W.

    1974-01-01

    The core clamping device for a fast neutron reactor includes clamps to support the fuel zone against the pressure vessel. The clamps are arranged around the circumference of the core. They consist of torsion bars arranged parallel at some distance around the core with lever arms attached to the ends whose force is directed in the opposite direction, pressing against the wall of the pressure vessel. The lever arms and pressure plates also actuated by the ends of the torsion bars transfer the stress, the pressure plates acting upon the fuel elements or fuel assemblies. Coupling between the ends of the torsion bars and the pressure plates is achieved by end carrier plates directly attached to the torsion bars and radially movable. This clamping device follows the thermal expansions of the core, allows specific elements to be disengaged in sections and saves space between the core and the neutron reflectors. (DG) [de

  8. The system of high-voltage power PMT for experiments at the JINR Nuclotron

    International Nuclear Information System (INIS)

    Piyadin, S.M.; Ladygin, V.P.; Pilyar, A.V.; Reznikov, S.G.; Janek, M.

    2015-01-01

    An 8-channel high-voltage power system based on the use of the module «Wenzel Elektronik N1130» is described. Specifications of control modules 8DAC-12 and 8ADC-14 designed for the high-voltage systems in CAMAC standard are presented. This system is designed to provide the power for the detectors used in physics experiments at the JINR Nuclotron.

  9. A 3D-Space Vector Modulation Algorithm for Three Phase Four Wire Neutral Point Clamped Inverter Systems as Power Quality Compensator

    Directory of Open Access Journals (Sweden)

    Palanisamy Ramasamy

    2017-11-01

    Full Text Available A Unified Power Quality Conditioner (UPQC is designed using a Neutral Point Clamped (NPC multilevel inverter to improve the power quality. When designed for high/medium voltage and power applications, the voltage stress across the switches and harmonic content in the output voltage are increased. A 3-phase 4-wire NPC inverter system is developed as Power Quality Conditioner using an effectual three dimensional Space Vector Modulation (3D-SVM technique. The proposed system behaves like a UPQC with shunt and series active filter under balanced and unbalanced loading conditions. In addition to the improvement of the power quality issues, it also balances the neutral point voltage and voltage balancing across the capacitors under unbalanced condition. The hardware and simulation results of proposed system are compared with 2D-SVM and 3D-SVM. The proposed system is stimulated using MATLAB and the hardware is designed using FPGA. From the results it is evident that effectual 3D-SVM technique gives better performance compared to other control methods.

  10. π-Clamp-mediated cysteine conjugation

    Science.gov (United States)

    Zhang, Chi; Welborn, Matthew; Zhu, Tianyu; Yang, Nicole J.; Santos, Michael S.; van Voorhis, Troy; Pentelute, Bradley L.

    2016-02-01

    Site-selective functionalization of complex molecules is one of the most significant challenges in chemistry. Typically, protecting groups or catalysts must be used to enable the selective modification of one site among many that are similarly reactive, and general strategies that selectively tune the local chemical environment around a target site are rare. Here, we show a four-amino-acid sequence (Phe-Cys-Pro-Phe), which we call the ‘π-clamp’, that tunes the reactivity of its cysteine thiol for site-selective conjugation with perfluoroaromatic reagents. We use the π-clamp to selectively modify one cysteine site in proteins containing multiple endogenous cysteine residues. These examples include antibodies and cysteine-based enzymes that would be difficult to modify selectively using standard cysteine-based methods. Antibodies modified using the π-clamp retained binding affinity to their targets, enabling the synthesis of site-specific antibody-drug conjugates for selective killing of HER2-positive breast cancer cells. The π-clamp is an unexpected approach to mediate site-selective chemistry and provides new avenues to modify biomolecules for research and therapeutics.

  11. A voltage regulator system with dynamic bandwidth boosting for passive UHF RFID transponders

    International Nuclear Information System (INIS)

    Shen Jinpeng; Wang Xin'an; Liu Shan; Li Shoucheng; Ruan Zhengkun

    2013-01-01

    This paper presents a voltage regulator system for passive UHF RFID transponders, which contains a rectifier, a limiter, and a regulator. The rectifier achieves power by rectifying the incoming RF energy. Due to the huge variation of the rectified voltage, a limiter at the rectifier output is used to clamp the rectified voltage. In this paper, the design of a limiter circuit is discussed in detail, which can provide a stable limiting voltage with low sensitivity to temperature variation and process dispersion. The key aspect of the voltage regulator system is the dynamic bandwidth boosting in the regulator. By sensing the excess current that is bypassed in the limiter during periods of excess energy, the bias current as well as the bandwidth of the regulator are increased, the output supply voltage can recover quickly from line transients during the periods of no RF energy to a full blast of RF energy. This voltage regulator system is implemented in a 0.18 μm CMOS process. (semiconductor integrated circuits)

  12. Mechanical nonlinearity elimination with a micromechanical clamped-free semicircular beams resonator

    Science.gov (United States)

    Chen, Dongyang; Chen, Xuying; Wang, Yong; Liu, Xinxin; Guan, Yangyang; Xie, Jin

    2018-04-01

    This paper reports a micro-machined clamped-free semicircular beam resonator aiming to eliminate the nonlinearity that widely exists in traditional mechanical resonators. Cubic coefficients over vibration displacement due to axial extension of the beams are analyzed through theoretical modelling, and the corresponding frequency effect is demonstrated. With the device working in the elastic vibration mode, the cubic coefficients are eliminated by using a free end to release the nonlinear extension of beams and thus the inside axial stress. The amplitude-frequency (A-f) effect is overcome in a large region of source power, and the coefficient of frequency softening is linearized in a large region of polarization voltage. As a result, the resonator can be driven at larger vibration amplitude to achieve a high signal to noise ratio and power handling performance.

  13. 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...

  14. A high voltage pulse generator based on silicon-controlled rectifier for field-reversed configuration experiment.

    Science.gov (United States)

    Lin, Munan; Liu, Ming; Zhu, Guanghui; Wang, Yanpeng; Shi, Peiyun; Sun, Xuan

    2017-08-01

    A high voltage pulse generator based on a silicon-controlled rectifier has been designed and implemented for a field reversed configuration experiment. A critical damping circuit is used in the generator to produce the desired pulse waveform. Depending on the load, the rise time of the output trigger signal can be less than 1 μs, and the peak amplitudes of trigger voltage and current are up to 8 kV and 85 A in a single output. The output voltage can be easily adjusted by changing the voltage on a capacitor of the generator. In addition, the generator integrates an electrically floating heater circuit so it is capable of triggering either pseudosparks (TDI-type hydrogen thyratron) or ignitrons. Details of the circuits and their implementation are described in the paper. The trigger generator has successfully controlled the discharging sequence of the pulsed power supply for a field reversed configuration experiment.

  15. Biological cell controllable patch-clamp microchip

    Science.gov (United States)

    Penmetsa, Siva; Nagrajan, Krithika; Gong, Zhongcheng; Mills, David; Que, Long

    2010-12-01

    A patch-clamp (PC) microchip with cell sorting and positioning functions is reported, which can avoid drawbacks of random cell selection or positioning for a PC microchip. The cell sorting and positioning are enabled by air bubble (AB) actuators. AB actuators are pneumatic actuators, in which air pressure is generated by microheaters within sealed microchambers. The sorting, positioning, and capturing of 3T3 cells by this type of microchip have been demonstrated. Using human breast cancer cells MDA-MB-231 as the model, experiments have been demonstrated by this microchip as a label-free technical platform for real-time monitoring of the cell viability.

  16. Multi-stage LLC resonant converters designed for wide output voltage ranges

    OpenAIRE

    Tsang, C.-W.; Bingham, C. M.; Foster, M. P.; Stone, D. A.; Leech, J. M.

    2016-01-01

    The paper describes a novel multi-stage LLC resonant converter topology for facilitating wide output voltage ranges. This is achieved by combining the gain range of a capacitor-diode clamped LLC resonant converter with that of a traditional LLC resonant converter. A prototype converter is designed and commissioned to illustrate the design procedure and demonstrate resulting operational characteristics. Experimental results are used to show operational characteristics of the proposed conver...

  17. ß-adrenergic regulation of ion transport in pancreatic ducts: Patch-clamp study of isolated rat pancreatic ducts

    DEFF Research Database (Denmark)

    Novak, I

    1998-01-01

    BACKGROUND & AIMS: In the intact pancreas, bicarbonate secretion is thought to be controlled by a number of regulators, including adrenergic agonists. The aim of this study was to investigate the effects of adrenergic agonists on pancreatic ducts, which are the site of bicarbonate secretion....... METHODS: Small intralobular ducts were isolated from rat pancreas and studied in vitro by the whole-cell patch clamp technique. Cell membrane voltages and currents were indicators of cellular ion transport. In some ducts, intracellular Ca2+ activity was measured by fluorescence optical methods. RESULTS...

  18. 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...

  19. A new clamp method for firing bricks | Obeng | Journal of Applied ...

    African Journals Online (AJOL)

    A new clamp method for firing bricks. ... Journal of Applied Science and Technology ... To overcome this operational deficiencies, a new method of firing bricks that uses brick clamp technique that incorporates a clamp wall of 60 cm thickness, a six tier approach of sealing the top of the clamp (by combination of green bricks) ...

  20. Method to Minimize the Low-Frequency Neutral-Point Voltage Oscillations With Time-Offset Injection for Neutral-Point-Clamped Inverters

    DEFF Research Database (Denmark)

    Choi, Ui-Min; Blaabjerg, Frede; Lee, Kyo-Beum

    2015-01-01

    time of small- and medium-voltage vectors. However, if the power factor is lower, there is a limitation to eliminate neutral-point oscillations. In this case, the proposed method can be improved by changing the switching sequence properly. Additionally, a method for neutral-point voltage balancing......This paper proposes a method to reduce the low-frequency neutral-point voltage oscillations. The neutral-point voltage oscillations are considerably reduced by adding a time offset to the three-phase turn-on times. The proper time offset is simply calculated considering the phase currents and dwell...

  1. Gigaseal formation in patch clamping with applications of nanotechnology

    CERN Document Server

    Malboubi, Majid

    2014-01-01

    This book presents an investigation of gigaseal formation using micro/nanotechnology. The aims of the book are twofold. First, it explains the mechanisms of gigaseal formation using the latest discoveries. Second, it provides practical techniques for frequent formation of high resistance seals. The formation of a high-resistance electrical seal, also known as a gigaseal, between a cell membrane and a glass micropipette tip is essential in patch-clamp experiments. Even though four decades have passed since the introduction of the patch-clamping technique by Neher and Sakmann, gigaseal formation remains an obstacle in developing the high-throughput ion channel screening systems required by the pharmaceutical industry. Here the authors share their latest methods for achieving gigaseal formation and describe techniques that are highly desirable at both research and industrial levels. Nanotechnology has been found to be a powerful tool for studying and modifying glass micropipettes and in tackling the problem of g...

  2. Is "Delayed Umbilical Cord Clamping" Beneficial for Premature Newborns?

    Directory of Open Access Journals (Sweden)

    Amir-Mohammad Armanian

    2017-05-01

    Full Text Available Background: The appropriate moment for clamping the umbilical cord is controversial. Immediate cord clamping (ICC is an item of active management of the third stage of labor (AMTSL. Unclamped umbilical cord may cause inconvenience in preterm neonates because they commonly need some levels of emergent services. Some studies revealed delayed cord clamping (DCC of preterm neonates results in better health conditions like lower rates of respiratory distress syndrome (RDS, less morbidities in labor room and lower risk of postpartum hemorrhage. The aim of the present study was to determine the effect of delayed umbilical cord clamping on premature neonatal outcomes. Materials and Methods: In this single‑center randomized control trial study, sixty premature neonates (gestational age ≤ 34 weeks were randomly assigned to ICC (cord clamped at 5–10 seconds or DCC (30–45 seconds groups and followed up in neonatal intensive care unit (NICU. Primary outcomes were 1st and 5th minute Apgar score, average of level of hematocrit after birth, intra ventricle hemorrhage and need some levels of resuscitation. Results: Differences in demographic characteristics were not statistically significant. After birth, neonates who had delayed clamping had significantly higher mean hematocrit after at 4-hour of birth (49.58+5.15gr/dl vs. 46.58+5.40gr/dlin DCC vs. ICC groups, respectively (P=0.031. Delayed cord clamping reduced the duration of need to nasal continues positive airway pressure (NCPAP (86.7% and 60.0% in ICC and DCC groups, respectively, P= 0.039. Attractively, the results showed lower incidence of clinical sepsis in delayed cord clamping neonates (53.3% vs. 23.3% in ICC and DCC groups, respectively, P=0.033. Conclusion: Prematurity complications might decrease by delay umbilical cord clamping which improve the hematocrit, duration of need to NCPAP and incidence of clinical sepsis. Furthermore, DCC may have no negative impact on neonatal resuscitation.

  3. An approach for high voltage power supply system for HCAL of LHCb experiment

    International Nuclear Information System (INIS)

    Cimpean, A.; Dumitru, D.; Kluger, A.; Magureanu, C.; Tarta, D.; Coca, C.; Orlandea, M.; Popescu, S.

    2003-01-01

    The main aim of the calorimeter system of the LHCb (Large Hadron Collider Beauty) experiment dedicated to precision measurements of CP violation and rare phenomena is to provide identification of the electrons, hadrons and photons, for the level-0 trigger and offline analysis with measurements of position and energy. The system consists in a scintillator pad/preshower (SPD/PS) detector, an electromagnetic calorimeter (ECAL) and a hadron calorimeter (HCAL), all the sub-detectors having a similar technology with scintillating tiles as active material and being read out via wavelength-shifting fibers and with an identical readout electronics for ECAL and HCAL and similar electronics for the PS. During 1997-1999 a computer controlled High Voltage (HV) distribution scheme was developed by Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH) group and used to supply the PMTs of half HCAL prototype during the beam tests (1998-2000). This scheme consisted of three parts: 1) a control box which includes low voltage power supply, the RS232 interface to a PC and three modules of high voltage power supply; 2) two types of multichannel HV distributors with an individual voltage setting; 3) a software package to control all settings and refresh them periodically. Based on the acquired experience, a new design for a High Voltage Power Supply (HVPS) which satisfies the LHCb requirements has been developed for PMTs of the hadron calorimeter. The demands of this system are simplicity and low cost. This HVPS with multiple outputs (HV for photocathode and D1 - D4 dynodes) is destined to supply, with the same high voltage, groups of PMTs sorted by similar characteristics as gain and sensitivity. Because of the high rates (∼ 40 MHz) supported by PMTs, booster voltage sources are necessary to supply current for the last 4 dynodes. The box has 5 HV power supplies for photocathodes and the last 4 dynodes, each HV power supply being followed by a 4 channel

  4. A missing factor in chip-based patch clamp assay: gigaseal

    International Nuclear Information System (INIS)

    Ong, W-L; Yobas, L; Ong, W-Y

    2006-01-01

    The 'gold' standard in the study of ionic currents across biological membranes is the Patch Clamp method. However, this is a slow, labor and skill intensive process. High throughput patch clamp devices are mainly chip-based. A major challenge in these miniaturized devices is the low rate of 'Gigaseal' formation which is critical in the study of Single Channel effect. In a conventional patch clamp, a pipette moves and patches a fixed cell (cell-adhered patch) which is grown on the bottom of a Petri dish. In the chip-based case, the cells are in suspension and move towards the fixed patch clamp sites (cell-suspended patch). In this study, using the proven conventional patch clamp setup, we investigated the effect of the differences in the cell configurations between the convention patch clamp and cell-based patch clamp. It is shown that adhered cells (as used in the conventional setup) have a much higher rate of gigaseal formation as compared to the cells in suspension (as used in chip-based devices). We postulate that the arrangement of the cytoskeleton within the cell plays a major part in the formation of the gigaseal

  5. Patch-Clamp Recording from Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes: Improving Action Potential Characteristics through Dynamic Clamp

    Science.gov (United States)

    Veerman, Christiaan C.; Zegers, Jan G.; Mengarelli, Isabella; Bezzina, Connie R.

    2017-01-01

    Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold great promise for studying inherited cardiac arrhythmias and developing drug therapies to treat such arrhythmias. Unfortunately, until now, action potential (AP) measurements in hiPSC-CMs have been hampered by the virtual absence of the inward rectifier potassium current (IK1) in hiPSC-CMs, resulting in spontaneous activity and altered function of various depolarising and repolarising membrane currents. We assessed whether AP measurements in “ventricular-like” and “atrial-like” hiPSC-CMs could be improved through a simple, highly reproducible dynamic clamp approach to provide these cells with a substantial IK1 (computed in real time according to the actual membrane potential and injected through the patch-clamp pipette). APs were measured at 1 Hz using perforated patch-clamp methodology, both in control cells and in cells treated with all-trans retinoic acid (RA) during the differentiation process to increase the number of cells with atrial-like APs. RA-treated hiPSC-CMs displayed shorter APs than control hiPSC-CMs and this phenotype became more prominent upon addition of synthetic IK1 through dynamic clamp. Furthermore, the variability of several AP parameters decreased upon IK1 injection. Computer simulations with models of ventricular-like and atrial-like hiPSC-CMs demonstrated the importance of selecting an appropriate synthetic IK1. In conclusion, the dynamic clamp-based approach of IK1 injection has broad applicability for detailed AP measurements in hiPSC-CMs. PMID:28867785

  6. Improved Active-Neutral-Point-Clamped (I-ANPC) Multilevel Converter: Fundamental Circuit Topology, Innovative Modulatioin Technique, and Experimental Validation

    DEFF Research Database (Denmark)

    Dargahi, Vahid; Corzine, Keith A.; Enslin, Johan H.

    2018-01-01

    For medium-voltage (MV) high-power industrial applications including HVDC and variable-speed motor drives, multilevel converters are deemed predominant topology. One of the promising derived-topologies from neutral-point-clamped (NPC) configuration is active NPC (ANPC) inverter that offers improved......-capacitor (FC) and four switches such as the insulated-gate bipolar transistors (IGBTs). The I-ANPC converter has considerable advantages over the classic multilevel inverters that makes it a preferable topology for MV applications. The substantial reduction in the number of cells in comparison with classic...

  7. Calmodulin and calcium differentially regulate the neuronal Nav1.1 voltage-dependent sodium channel

    Energy Technology Data Exchange (ETDEWEB)

    Gaudioso, Christelle; Carlier, Edmond; Youssouf, Fahamoe [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France); Clare, Jeffrey J. [Eaton Pharma Consulting, Eaton Socon, Cambridgeshire PE19 8EF (United Kingdom); Debanne, Dominique [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France); Alcaraz, Gisele, E-mail: gisele.alcaraz@univmed.fr [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France)

    2011-07-29

    Highlights: {yields} Both Ca{sup ++}-Calmodulin (CaM) and Ca{sup ++}-free CaM bind to the C-terminal region of Nav1.1. {yields} Ca{sup ++} and CaM have both opposite and convergent effects on I{sub Nav1.1}. {yields} Ca{sup ++}-CaM modulates I{sub Nav1.1} amplitude. {yields} CaM hyperpolarizes the voltage-dependence of activation, and increases the inactivation rate. {yields} Ca{sup ++} alone antagonizes CaM for both effects, and depolarizes the voltage-dependence of inactivation. -- Abstract: Mutations in the neuronal Nav1.1 voltage-gated sodium channel are responsible for mild to severe epileptic syndromes. The ubiquitous calcium sensor calmodulin (CaM) bound to rat brain Nav1.1 and to the human Nav1.1 channel expressed by a stably transfected HEK-293 cell line. The C-terminal region of the channel, as a fusion protein or in the yeast two-hybrid system, interacted with CaM via a consensus C-terminal motif, the IQ domain. Patch clamp experiments on HEK1.1 cells showed that CaM overexpression increased peak current in a calcium-dependent way. CaM had no effect on the voltage-dependence of fast inactivation, and accelerated the inactivation kinetics. Elevating Ca{sup ++} depolarized the voltage-dependence of fast inactivation and slowed down the fast inactivation kinetics, and for high concentrations this effect competed with the acceleration induced by CaM alone. Similarly, the depolarizing action of calcium antagonized the hyperpolarizing shift of the voltage-dependence of activation due to CaM overexpression. Fluorescence spectroscopy measurements suggested that Ca{sup ++} could bind the Nav1.1 C-terminal region with micromolar affinity.

  8. Monitoring voltage-dependent charge displacement of Shaker B-IR K+ ion channels using radio frequency interrogation.

    Directory of Open Access Journals (Sweden)

    Sameera Dharia

    2011-02-01

    Full Text Available Here we introduce a new technique that probes voltage-dependent charge displacements of excitable membrane-bound proteins using extracellularly applied radio frequency (RF, 500 kHz electric fields. Xenopus oocytes were used as a model cell for these experiments, and were injected with cRNA encoding Shaker B-IR (ShB-IR K(+ ion channels to express large densities of this protein in the oocyte membranes. Two-electrode voltage clamp (TEVC was applied to command whole-cell membrane potential and to measure channel-dependent membrane currents. Simultaneously, RF electric fields were applied to perturb the membrane potential about the TEVC level and to measure voltage-dependent RF displacement currents. ShB-IR expressing oocytes showed significantly larger changes in RF displacement currents upon membrane depolarization than control oocytes. Voltage-dependent changes in RF displacement currents further increased in ShB-IR expressing oocytes after ∼120 µM Cu(2+ addition to the external bath. Cu(2+ is known to bind to the ShB-IR ion channel and inhibit Shaker K(+ conductance, indicating that changes in the RF displacement current reported here were associated with RF vibration of the Cu(2+-linked mobile domain of the ShB-IR protein. Results demonstrate the use of extracellular RF electrodes to interrogate voltage-dependent movement of charged mobile protein domains--capabilities that might enable detection of small changes in charge distribution associated with integral membrane protein conformation and/or drug-protein interactions.

  9. Monitoring voltage-dependent charge displacement of Shaker B-IR K+ ion channels using radio frequency interrogation.

    Science.gov (United States)

    Dharia, Sameera; Rabbitt, Richard D

    2011-02-28

    Here we introduce a new technique that probes voltage-dependent charge displacements of excitable membrane-bound proteins using extracellularly applied radio frequency (RF, 500 kHz) electric fields. Xenopus oocytes were used as a model cell for these experiments, and were injected with cRNA encoding Shaker B-IR (ShB-IR) K(+) ion channels to express large densities of this protein in the oocyte membranes. Two-electrode voltage clamp (TEVC) was applied to command whole-cell membrane potential and to measure channel-dependent membrane currents. Simultaneously, RF electric fields were applied to perturb the membrane potential about the TEVC level and to measure voltage-dependent RF displacement currents. ShB-IR expressing oocytes showed significantly larger changes in RF displacement currents upon membrane depolarization than control oocytes. Voltage-dependent changes in RF displacement currents further increased in ShB-IR expressing oocytes after ∼120 µM Cu(2+) addition to the external bath. Cu(2+) is known to bind to the ShB-IR ion channel and inhibit Shaker K(+) conductance, indicating that changes in the RF displacement current reported here were associated with RF vibration of the Cu(2+)-linked mobile domain of the ShB-IR protein. Results demonstrate the use of extracellular RF electrodes to interrogate voltage-dependent movement of charged mobile protein domains--capabilities that might enable detection of small changes in charge distribution associated with integral membrane protein conformation and/or drug-protein interactions.

  10. Protein associations in DnaA-ATP hydrolysis mediated by the Hda-replicase clamp complex.

    Science.gov (United States)

    Su'etsugu, Masayuki; Shimuta, Toh-Ru; Ishida, Takuma; Kawakami, Hironori; Katayama, Tsutomu

    2005-02-25

    In Escherichia coli, the activity of ATP-bound DnaA protein in initiating chromosomal replication is negatively controlled in a replication-coordinated manner. The RIDA (regulatory inactivation of DnaA) system promotes DnaA-ATP hydrolysis to produce the inactivated form DnaA-ADP in a manner depending on the Hda protein and the DNA-loaded form of the beta-sliding clamp, a subunit of the replicase holoenzyme. A highly functional form of Hda was purified and shown to form a homodimer in solution, and two Hda dimers were found to associate with a single clamp molecule. Purified mutant Hda proteins were used in a staged in vitro RIDA system followed by a pull-down assay to show that Hda-clamp binding is a prerequisite for DnaA-ATP hydrolysis and that binding is mediated by an Hda N-terminal motif. Arg(168) in the AAA(+) Box VII motif of Hda plays a role in stable homodimer formation and in DnaA-ATP hydrolysis, but not in clamp binding. Furthermore, the DnaA N-terminal domain is required for the functional interaction of DnaA with the Hda-clamp complex. Single cells contain approximately 50 Hda dimers, consistent with the results of in vitro experiments. These findings and the features of AAA(+) proteins, including DnaA, suggest the following model. DnaA-ATP is hydrolyzed at a binding interface between the AAA(+) domains of DnaA and Hda; the DnaA N-terminal domain supports this interaction; and the interaction of DnaA-ATP with the Hda-clamp complex occurs in a catalytic mode.

  11. Design and control of a novel gastroscope intervention mechanism with circumferentially pneumatic-driven clamping function.

    Science.gov (United States)

    Li, Yanmin; Liu, Hao; Hao, Siwen; Li, Hongyi; Han, Jianda; Yang, Yunsheng

    2017-03-01

    Robot-assisted manipulation is promising for solving problems such as understaffing and the risk of infection in gastro-intestinal endoscopy. However, the commonly used friction rollers in few existing systems have a potential risk of deforming flexible endoscopes for non-uniform clamping. This paper presents a robotic system for a standard flexible endoscope and focuses on a novel gastroscope intervention mechanism (GIM), which provides circumferentially uniform clamping with an airbag. The GIM works with a relay-on mechanism in a way similar to manual operation. The shear stiffness of airbag and the critical slipping force (CSF) were analysed to determine the parameters of the airbag. A fuzzy PID controller was employed to realize a fast response and high accuracy of pneumatic actuation. Experiments were performed to evaluate the accuracy, stiffness and CSF. In vitro and in vivo animal experiments were also carried out. The GIM realized an accuracy of 0.025 ± 0.2 mm and -0.03 ± 0.25° for push-pull and rotation without delivery resistance. Under polynomial could be used to describe the relationship between the CSF and pneumatic pressure. The novel GIM could effectively deliver gastroscopes. The pneumatic-driven clamping method proposed could protect the gastroscope by circumferentially uniform clamping force and the CSF could be properly controlled to guarantee operating safety. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Calibration of the precision high voltage dividers of the KATRIN experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rest, Oliver [Institut fuer Kernphysik, Westfaelische Wilhelms-Universitaet Muenster (Germany); Collaboration: KATRIN-Collaboration

    2016-07-01

    The KATRIN (KArlsruhe TRItium Neutrino) experiment will measure the endpoint region of the tritium β decay spectrum to determine the neutrino mass with a sensitivity of 200 meV/c{sup 2}. To achieve this sub-eV sensitivity the energy of the decay electrons will be analyzed using a MAC-E type spectrometer. The retarding potential of the MAC-E-filter (up to -35 kV) has to be monitored with a relative precision of 3 . 10{sup -6}. For this purpose the potential will be measured directly via two custom made precision high voltage dividers, which were developed and constructed in cooperation with the Physikalisch-Technische Bundesanstalt Braunschweig. In order to determine the absolute values and the stability of the scale factors of the voltage dividers, regular calibration measurements are essential. Such measurements have been performed during the last years using several different methods. The poster gives an overview of the methods and results of the calibration of the precision high voltage dividers.

  13. Reducing blood loss during laparoscopic myomectomy by temporary uterine artery clamping using bulldog clamp

    Directory of Open Access Journals (Sweden)

    Kai-Jo Chiang

    2014-01-01

    Full Text Available Uterine myoma is the most common benign gynecologic tumor worldwide. Mini-invasive surgery has become popular for myomectomy, with advantages over laparotomy. However, reducing blood loss during laparoscopic myomectomy is a major concern for the surgeon because of the limitation in making a quick control bleeding during the operation. Several methods have proved to decrease blood flow, but are not always effective or available. We present a case of uterine myoma with the uterine arteries clamped by bulldog clamps during laparoscopic myomectomy. The myoma was removed successfully with minimal blood loss (<50 ml during the operation. This is an effective, safe, and reliable method for reducing bleeding during laparoscopic myomectomy that does not require ligation of the uterine artery.

  14. Block of voltage-gated potassium channels by Pacific ciguatoxin-1 contributes to increased neuronal excitability in rat sensory neurons

    International Nuclear Information System (INIS)

    Birinyi-Strachan, Liesl C.; Gunning, Simon J.; Lewis, Richard J.; Nicholson, Graham M.

    2005-01-01

    The present study investigated the actions of the polyether marine toxin Pacific ciguatoxin-1 (P-CTX-1) on neuronal excitability in rat dorsal root ganglion (DRG) neurons using patch-clamp recording techniques. Under current-clamp conditions, bath application of 2-20 nM P-CTX-1 caused a rapid, concentration-dependent depolarization of the resting membrane potential in neurons expressing tetrodotoxin (TTX)-sensitive voltage-gated sodium (Na v ) channels. This action was completely suppressed by the addition of 200 nM TTX to the external solution, indicating that this effect was mediated through TTX-sensitive Na v channels. In addition, P-CTX-1 also prolonged action potential and afterhyperpolarization (AHP) duration. In a subpopulation of neurons, P-CTX-1 also produced tonic action potential firing, an effect that was not accompanied by significant oscillation of the resting membrane potential. Conversely, in neurons expressing TTX-resistant Na v currents, P-CTX-1 failed to alter any parameter of neuronal excitability examined in this study. Under voltage-clamp conditions in rat DRG neurons, P-CTX-1 inhibited both delayed-rectifier and 'A-type' potassium currents in a dose-dependent manner, actions that occurred in the absence of alterations to the voltage dependence of activation. These actions appear to underlie the prolongation of the action potential and AHP, and contribute to repetitive firing. These data indicate that a block of potassium channels contributes to the increase in neuronal excitability, associated with a modulation of Na v channel gating, observed clinically in response to ciguatera poisoning

  15. Clinicians? and womens? experiences of two consent pathways in a trial of timing of clamping at very preterm birth: a qualitative study

    OpenAIRE

    Ayers, Susan; Sawyer, Alex; Chhoa, Celine; Pushpa-Rajah, Angela; Duley, Lelia

    2015-01-01

    Background\\ud Recruitment to trials when birth is imminent requires offering consent at a difficult and stressful time, often with limited time. The Cord Pilot Trial assessed timing of cord clamping at very preterm birth. To ensure high risk women were not excluded we developed a two stage oral assent pathway, for use when birth was imminent. A third of women were recruited using this pathway. The aim of this study was to explore clinicians’ and women’s’ experiences of the two consent pathway...

  16. Cation gating and selectivity in a purified, reconstituted, voltage-dependent sodium channel

    International Nuclear Information System (INIS)

    Barchi, R.L.; Tanaka, J.C.

    1984-01-01

    In excitable membranes, the voltage-dependent sodium channel controls the primary membrane conductance change necessary for the generation of an action potential. Over the past four decades, the time- and voltage-dependent sodium currents gated by this channel have been thoroughly documented with increasingly sophisticated voltage-clamp techniques. Recent advances in the biochemistry of membrane proteins have led to the solubilization and purification of this channel protein from nerve (6) and from muscle (4) or muscle-derived (1) membranes, and have provided an approach to the correlation of the channel's molecular structure with its functional properties. Each of these sodium channel preparations appears to contain a large glycoprotein either as its sole component (2) or in association with several small subunits (6, 3). Evidence that these purified proteins represent the excitable membrane sodium channel is presented. 8 refs., 1 fig., 1 tab

  17. Effects of trimethoprim-sulfadiazine and detomidine on the function of equine Kv 11.1 channels in a two-electrode voltage-clamp (TEVC) oocyte model.

    Science.gov (United States)

    Trachsel, D S; Tejada, M A; Groesfjeld Christensen, V; Pedersen, P J; Kanters, J K; Buhl, R; Calloe, K; Klaerke, D A

    2018-03-22

    The long QT syndrome (LQTS) is a channelopathy that can lead to severe arrhythmia and sudden cardiac death. Pharmacologically induced LQTS is caused by interaction between drugs and potassium channels, especially the K v 11.1 channel. Due to such interactions, numerous drugs have been withdrawn from the market or are administered with precautions in human medicine. However, some compounds, such as trimethoprim-sulfonamide combinations are still widely used in veterinarian medicine. Therefore, we investigate the effect of trimethoprim-sulfadiazine (TMS), trimethoprim, sulfadiazine, and detomidine on equine-specific K v 11.1 channels. K v 11.1 channels cloned from equine hearts were heterologously expressed in Xenopus laevis oocytes, and whole cell currents were measured by two-electrode voltage-clamp before and after drug application. TMS blocked equine K v 11.1 current with an IC 50 of 3.74 mm (95% CI: 2.95-4.73 mm) and affected the kinetics of activation and inactivation. Similar was found for trimethoprim but not for sulfadiazine, suggesting the effect is due to trimethoprim. Detomidine did not affect equine K v 11.1 current. Thus, equine K v 11.1 channels are also susceptible to pharmacological block, indicating that some drugs may have the potential to affect repolarization in horse. However, in vivo studies are needed to assess the potential risk of these drugs to induce equine LQTS. © 2018 The Authors. Journal of Veterinary Pharmacology and Therapeutics Published by John Wiley & Sons Ltd.

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

    DEFF Research Database (Denmark)

    Chen, Quan; Wang, Qunjing; Chen, Zhe

    2014-01-01

    Three-level Neutral-point-clamped (3L-NPC) converters are becoming a realistic alternative to the conventional converters in high-power wind-energy applications. But the unbalance in the supported capacitors' voltage of back-to-back 3L-NPC converters, including the dynamics of the capacitors...... between the fluctuate voltage of upper and lower capacitors is extracted. Based on this error factor the duty-time of every active voltage vector is calculated. In order to validate the model and the control strategy proposed in this paper, a 2MW 3L-NPC converter used in wind energy has been simulated....

  19. Automated sampling and data processing derived from biomimetic membranes

    International Nuclear Information System (INIS)

    Perry, M; Vissing, T; Hansen, J S; Nielsen, C H; Boesen, T P; Emneus, J

    2009-01-01

    Recent advances in biomimetic membrane systems have resulted in an increase in membrane lifetimes from hours to days and months. Long-lived membrane systems demand the development of both new automated monitoring equipment capable of measuring electrophysiological membrane characteristics and new data processing software to analyze and organize the large amounts of data generated. In this work, we developed an automated instrumental voltage clamp solution based on a custom-designed software controller application (the WaveManager), which enables automated on-line voltage clamp data acquisition applicable to long-time series experiments. We designed another software program for off-line data processing. The automation of the on-line voltage clamp data acquisition and off-line processing was furthermore integrated with a searchable database (DiscoverySheet(TM)) for efficient data management. The combined solution provides a cost efficient and fast way to acquire, process and administrate large amounts of voltage clamp data that may be too laborious and time consuming to handle manually. (communication)

  20. Automated sampling and data processing derived from biomimetic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Perry, M; Vissing, T; Hansen, J S; Nielsen, C H [Aquaporin A/S, Diplomvej 377, DK-2800 Kgs. Lyngby (Denmark); Boesen, T P [Xefion ApS, Kildegaardsvej 8C, DK-2900 Hellerup (Denmark); Emneus, J, E-mail: Claus.Nielsen@fysik.dtu.d [DTU Nanotech, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2009-12-15

    Recent advances in biomimetic membrane systems have resulted in an increase in membrane lifetimes from hours to days and months. Long-lived membrane systems demand the development of both new automated monitoring equipment capable of measuring electrophysiological membrane characteristics and new data processing software to analyze and organize the large amounts of data generated. In this work, we developed an automated instrumental voltage clamp solution based on a custom-designed software controller application (the WaveManager), which enables automated on-line voltage clamp data acquisition applicable to long-time series experiments. We designed another software program for off-line data processing. The automation of the on-line voltage clamp data acquisition and off-line processing was furthermore integrated with a searchable database (DiscoverySheet(TM)) for efficient data management. The combined solution provides a cost efficient and fast way to acquire, process and administrate large amounts of voltage clamp data that may be too laborious and time consuming to handle manually. (communication)

  1. File list: Oth.ALL.50.Clamp.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.50.Clamp.AllCell dm3 TFs and others Clamp All cell types SRX159172,SRX15917...0,SRX159174,SRX159166,SRX159173 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.ALL.50.Clamp.AllCell.bed ...

  2. High voltage load resistor array

    Science.gov (United States)

    Lehmann, Monty Ray [Smithfield, VA

    2005-01-18

    A high voltage resistor comprising an array of a plurality of parallel electrically connected resistor elements each containing a resistive solution, attached at each end thereof to an end plate, and about the circumference of each of the end plates, a corona reduction ring. Each of the resistor elements comprises an insulating tube having an electrode inserted into each end thereof and held in position by one or more hose clamps about the outer periphery of the insulating tube. According to a preferred embodiment, the electrode is fabricated from stainless steel and has a mushroom shape at one end, that inserted into the tube, and a flat end for engagement with the end plates that provides connection of the resistor array and with a load.

  3. E-beam high voltage switching power supply

    Science.gov (United States)

    Shimer, Daniel W.; Lange, Arnold C.

    1997-01-01

    A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360.degree./n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load.

  4. E-beam high voltage switching power supply

    International Nuclear Information System (INIS)

    Shimer, D.W.; Lange, A.C.

    1997-01-01

    A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360 degree/n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load. 7 figs

  5. A New Approach to High Efficincy in Isolated Boost Converters for High-Power Low-Voltage Fuel Cell Apllications

    DEFF Research Database (Denmark)

    Nymand, Morten; Andersen, Michael A. E.

    2008-01-01

    A new low-leakage-inductance low-resistance design approach to low-voltage high-power isolated boost converters is presented. Very low levels of parasitic circuit inductances are achieved by optimizing transformer design and circuit lay-out. Primary side voltage clamp circuits can be eliminated...... by the use of power MOSFETs fully rated for repetitive avalanche. Voltage rating of primary switches can now be reduced, significantly reducing switch on-state losses. Finally, silicon carbide rectifying diodes allow fast diode turn-off, further reducing losses. Test results from a 1.5 kW full-bridge boost...... converter verify theoretical analysis and demonstrate very high efficiency. Worst case efficiency, at minimum input voltage maximum power, is 96.8 percent and maximum efficiency reaches 98 percent....

  6. 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.

  7. Niflumic acid alters gating of HCN2 pacemaker channels by interaction with the outer region of S4 voltage sensing domains.

    Science.gov (United States)

    Cheng, Lan; Sanguinetti, Michael C

    2009-05-01

    Niflumic acid, 2-[[3-(trifluoromethyl)phenyl]amino]pyridine-3-carboxylic acid (NFA), is a nonsteroidal anti-inflammatory drug that also blocks or modifies the gating of many ion channels. Here, we investigated the effects of NFA on hyperpolarization-activated cyclic nucleotide-gated cation (HCN) pacemaker channels expressed in X. laevis oocytes using site-directed mutagenesis and the two-electrode voltage-clamp technique. Extracellular NFA acted rapidly and caused a slowing of activation and deactivation and a hyperpolarizing shift in the voltage dependence of HCN2 channel activation (-24.5 +/- 1.2 mV at 1 mM). Slowed channel gating and reduction of current magnitude was marked in oocytes treated with NFA, while clamped at 0 mV but minimal in oocytes clamped at -100 mV, indicating the drug preferentially interacts with channels in the closed state. NFA at 0.1 to 3 mM shifted the half-point for channel activation in a concentration-dependent manner, with an EC(50) of 0.54 +/- 0.068 mM and a predicted maximum shift of -38 mV. NFA at 1 mM also reduced maximum HCN2 conductance by approximately 20%, presumably by direct block of the pore. The rapid onset and state-dependence of NFA-induced changes in channel gating suggests an interaction with the extracellular region of the S4 transmembrane helix, the primary voltage-sensing domain of HCN2. Neutralization (by mutation to Gln) of any three of the outer four basic charged residues in S4, but not single mutations, abrogated the NFA-induced shift in channel activation. We conclude that NFA alters HCN2 gating by interacting with the extracellular end of the S4 voltage sensor domains.

  8. DC dynamic pull-in predictions for a generalized clamped–clamped micro-beam based on a continuous model and bifurcation analysis

    International Nuclear Information System (INIS)

    Chao, Paul C-P; Chiu, C W; Liu, Tsu-Hsien

    2008-01-01

    This study is devoted to providing precise predictions of the dc dynamic pull-in voltages of a clamped–clamped micro-beam based on a continuous model. A pull-in phenomenon occurs when the electrostatic force on the micro-beam exceeds the elastic restoring force exerted by beam deformation, leading to contact between the actuated beam and bottom electrode. DC dynamic pull-in means that an instantaneous application of the voltage (a step function such as voltage) is applied. To derive the pull-in voltage, a dynamic model in partial differential equations is established based on the equilibrium among beam flexibility, inertia, residual stress, squeeze film, distributed electrostatic forces and its electrical field fringing effects. The method of Galerkin decomposition is then employed to convert the established system equations into reduced discrete modal equations. Considering lower-order modes and approximating the beam deflection by a different order series, bifurcation based on phase portraits is conducted to derive static and dynamic pull-in voltages. It is found that the static pull-in phenomenon follows dynamic instabilities, and the dc dynamic pull-in voltage is around 91–92% of the static counterpart. However, the derived dynamic pull-in voltage is found to be dependent on the varied beam parameters, different from a fixed predicted value derived in past works, where only lumped models are assumed. Furthermore, accurate closed-form predictions are provided for non-narrow beams. The predictions are finally validated by finite element analysis and available experimental data

  9. The Dynamics of a Doubly Clamped Microbeam Near the Primary Resonance: Experimental and Analytical Investigation

    KAUST Repository

    Masri, Karim M.

    2016-01-20

    We present experimental and analytical investigation of the dynamics of a doubly clamped microbeam near its primary resonance. The microbeam is excited electrostatically by an electrode on the first half of the beam. These microbeams are fabricated using polyimide as structural layer coated with nickel from top and chromium and gold layers from bottom. A noise signal is applied to experimentally detect the natural frequencies. Then, frequency sweep tests are generated for various values of DC bias revealing hardening, transition, and softening behavior of the microbeam. We report for the first time the transition from lower stable state, to unstable state, and then to large stable state experimentally. A multi-mode Galerkin method is used to develop a reduced order model (ROM) of the beam. Shooting method is used to find the periodic motion and is utilized to generate frequency response curves. The curves show good agreement with the experimental results with hardening behavior at lower DC voltage then softening at higher voltage loads and dynamic pull-in. © Copyright 2015 by ASME.

  10. Robust Clamping Force Control of an Electro-Mechanical Brake System for Application to Commercial City Buses

    Directory of Open Access Journals (Sweden)

    Sangjune Eum

    2017-02-01

    Full Text Available This paper proposes a sensor-less robust force control method for improving the control performance of an electro-mechanical brake (EMB which is applicable to commercial city buses. The EMB generates the accurate clamping force commanded by a driver through an independent motor control at each wheel instead of using existing mechanical components. In general, an EMB undergoes parameter variation and a backdrivability problem. For this reason, the cascade control strategy (e.g., force-position cascade control structure is proposed and the disturbance observer is employed to enhance control robustness against model variations. Additionally, this paper proposed the clamping force estimation method for a sensor-less control, i.e., the clamping force observer (CFO. Finally, in order to confirm the performance and effectiveness of a proposed robust control method, several experiments are performed and analyzed.

  11. Experimental background of pain treatment by heat application - rapid heating and cooling in patch clamp experiments

    Czech Academy of Sciences Publication Activity Database

    Dittert, Ivan; Slovák, P.; Jíra, J.

    2005-01-01

    Roč. 8, Suppl.2 (2005), s. 32-32 ISSN 1212-0634. [Česko-Slovenské dialógy o bolesti /7./. 13.10.2005 - 15.10.2005, Bojnice] Institutional research plan: CEZ:AV0Z50110509 Keywords : patch clamp * channels Subject RIV: CF - Physical ; Theoretical Chemistry

  12. Comparative Evaluation of Pulsewidth Modulation Strategies for Z-Source Neutral-Point-Clamped Inverter

    DEFF Research Database (Denmark)

    Loh, P.C.; Blaabjerg, Frede; Wong, C.P.

    2007-01-01

    modulation (PWM) strategies for controlling the Z-source NPC inverter. While developing the PWM techniques, attention has been devoted to carefully derive them from a common generic basis for improved portability, easier implementation, and most importantly, assisting readers in understanding all concepts......Z-source neutral-point-clamped (NPC) inverter has recently been proposed as an alternative three-level buck-boost power conversion solution with an improved output waveform quality. In principle, the designed Z-source inverter functions by selectively "shooting through" its power sources, coupled...... to the inverter using two unique Z-source impedance networks, to boost the inverter three-level output waveform. Proper modulation of the new inverter would therefore require careful integration of the selective shoot-through process to the basic switching concepts to achieve maximal voltage-boost, minimal...

  13. The high-voltage monitor system for the calorimeter of the OBELIX experiment

    International Nuclear Information System (INIS)

    Bertin, A.; Bruschi, M.; Capponi, M.; Cereda, B.; D'Antone, I.; De Castro, S.; Galli, D.; Giacobbe, B.; Marconi, U.; Massa, I.; Piccinini, M.; Poli, M.; Semprini-Cesari, N.; Spighi, R.; Vecchi, S.; Vezzani, A.; Villa, M.; Vitale, A.; Zoccoli, A.

    1993-01-01

    We describe the monitor system developed to manage the high voltage power supply for the electromagnetic calorimeter of the OBELIX experiment, installed on the LEAR facility at CERN. The hardware and software characteristics of the system are discussed, as well as the performance of the same. (orig.)

  14. Crystal structure of DNA polymerase III β sliding clamp from Mycobacterium tuberculosis.

    Science.gov (United States)

    Gui, Wen-Jun; Lin, Shi-Qiang; Chen, Yuan-Yuan; Zhang, Xian-En; Bi, Li-Jun; Jiang, Tao

    2011-02-11

    The sliding clamp is a key component of DNA polymerase III (Pol III) required for genome replication. It is known to function with diverse DNA repair proteins and cell cycle-control proteins, making it a potential drug target. To extend our understanding of the structure/function relationship of the sliding clamp, we solved the crystal structure of the sliding clamp from Mycobacterium tuberculosis (M. tuberculosis), a human pathogen that causes most cases of tuberculosis (TB). The sliding clamp from M. tuberculosis forms a ring-shaped head-to-tail dimer with three domains per subunit. Each domain contains two α helices in the inner ring that lie against two β sheets in the outer ring. Previous studies have indicated that many Escherichia coli clamp-binding proteins have a conserved LF sequence, which is critical for binding to the hydrophobic region of the sliding clamp. Here, we analyzed the binding affinities of the M. tuberculosis sliding clamp and peptides derived from the α and δ subunits of Pol III, which indicated that the LF motif also plays an important role in the binding of the α and δ subunits to the sliding clamp of M. tuberculosis. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Tuning permanent magnets with adjustable field clamps

    International Nuclear Information System (INIS)

    Schermer, R.I.

    1987-01-01

    The effective length of a permanent-magnet assembly can be varied by adjusting the geometrical parameters of a field clamp. This paper presents measurements on a representative dipole and quadrupole as the field clamp is withdrawn axially or radially. The detailed behavior depends upon the magnet multipolarity and geometry. As a rule-of-thumb, a 3-mm-thick iron plate placed at one end plane of the magnet will shorten the length by one-third of the magnet bore radius

  16. Method to minimize the low-frequency neutral-point voltage oscillations with time-offset injection for neutral-point-clamped inverters

    DEFF Research Database (Denmark)

    Choi, Uimin; Lee, Kyo-Beum; Blaabjerg, Frede

    2013-01-01

    This paper proposes a method to reduce the low-frequency neutral-point voltage oscillations. The neutral-point voltage oscillations are considerably reduced by adding a time-offset to the three phase turn-on times. The proper time-offset is simply calculated considering the phase currents and dwell...

  17. Kinetics of Ca2+- and ATP-dependent, voltage-controlled anion conductance in the plasma membrane of mesophyll cells of Pisum sativum

    NARCIS (Netherlands)

    Elzenga, J.T.M.; van Volkenburgh, E.

    Whole-cell patch-clamp techniques were used to measure anion currents through the plasma membrane of protoplasts of mesophyll cells of expanding pea (Pisum sativum L.) leaves. Voltage-induced changes of the currents could be modelled with single exponential activation and deactivation kinetics. The

  18. 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.

  19. File list: Oth.CeL.50.Clamp.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.CeL.50.Clamp.AllCell dm3 TFs and others Clamp Cell line SRX159172,SRX159170,SRX...159174,SRX159166,SRX159173 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.CeL.50.Clamp.AllCell.bed ...

  20. File list: Oth.CeL.05.Clamp.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.CeL.05.Clamp.AllCell dm3 TFs and others Clamp Cell line SRX159172,SRX159170,SRX...159174,SRX159166,SRX159173 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.CeL.05.Clamp.AllCell.bed ...

  1. [Analysis of brain hemometabolism behavior during carotid endarterectomy with temporary clamping.].

    Science.gov (United States)

    Duval Neto, Gastão Fernandes; Niencheski, Augusto H

    2004-04-01

    Carotid endarterectomy with temporary clamping changes cerebral blood flow and cerebral metabolic oxygen demand ratio with consequent oligemic hypoxia or hemometabolic uncoupling. This study aimed at identifying changes in brain hemometabolism, evaluated through changes in oxyhemoglobin saturation in internal jugular vein bulb (SvjO2) during carotid endarterectomy with clamping, and at correlating these changes with potentially interfering factors, mainly end tidal CO2 pressure (P ET CO2) and cerebral perfusion pressure (CPP). Sixteen patients with unilateral carotid stenotic disease scheduled to carotid endarterectomy with carotid arterial clamping were enrolled in this study. Parameters including internal jugular bulb oxyhemoglobin saturation, stump pressure and end tidal CO2 pressure were measured at the following moments: M1 - pre-clamping; M2 - 3 minutes after clamping; M3 - pre-unclamping; M4 - post-unclamping). The comparison among SvjO2 (%, mean +/- SD) in all studied periods has shown differences between those recorded in moments M1 (52.25 +/- 7.87) and M2 (47.43 +/- 9.19). This initial decrease stabilized during temporary clamping, showing decrease in the comparison between M2 and M3 (46.56 +/- 9.25), without statistical significance (p = ns). At post-unclamping, M4 (47.68 +/- 9.12), SvjO2 was increased as compared to M2 and M3 clamping stages, however it was still lower than that of pre-clamping stage M1.(M4 x M1 - p brain hemometabolic uncoupling trend were correlated to P ET CO2. The comparison between CPP and SvjO2 showed weak correlation devoid of statistical significance. In the conditions of our study, SvjO2 measurement is a fast and effective way of clinically monitoring changes in CBF/CMRO2 ratio. Temporary carotid clamping implies in a trend towards brain hemometabolic uncoupling and, as a consequence, to oligemic ischemia; cerebral perfusion pressure does not assesses brain hemometabolic status (CBF and CMRO2 ratio); hypocapnia, may lead to

  2. 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...

  3. Dynamics of T-Junction Solution Switching Aimed at Patch Clamp Experiments.

    Science.gov (United States)

    Auzmendi, Jerónimo A; Smoler, Mariano; Moffatt, Luciano

    2015-01-01

    Solutions exchange systems are responsible for the timing of drug application on patch clamp experiments. There are two basic strategies for generating a solution exchange. When slow exchanges are bearable, it is easier to perform the exchange inside the tubing system upstream of the exit port. On the other hand, fast, reproducible, exchanges are usually performed downstream of the exit port. As both strategies are combinable, increasing the performance of upstream exchanges is desirable. We designed a simple method for manufacturing T-junctions (300 μm I.D.) and we measured the time profile of exchange of two saline solutions using a patch pipette with an open tip. Three factors were found to determine the timing of the solution switching: pressure, travelled distance and off-center distance. A linear relationship between the time delay and the travelled distance was found for each tested pressure, showing its dependence to the fluid velocity, which increased with pressure. The exchange time was found to increase quadratically with the delay, although a sizeable variability remains unexplained by this relationship. The delay and exchange times increased as the recording pipette moved away from the center of the stream. Those increases became dramatic as the pipette was moved close to the stream borders. Mass transport along the travelled distance between the slow fluid at the border and the fast fluid at the center seems to contribute to the time course of the solution exchange. This effect would be present in all tubing based devices. Present results might be of fundamental importance for the adequate design of serial compound exchangers which would be instrumental in the discovery of drugs that modulate the action of the physiological agonists of ion channels with the purpose of fine tuning their physiology.

  4. Influence of squeeze film damping on the higher-order modes of clamped–clamped microbeams

    KAUST Repository

    Alcheikh, Nouha

    2016-05-06

    This paper presents an experimental study and a finite-element analysis of the effect of squeeze film damping on the resonance frequency and quality factor of the higher-order flexure vibrations modes of clamped-clamped microbeams. Viscoelastic and silicon nitride microbeams are fabricated and are electrostatically actuated by various electrode configurations to trigger the first, second, and third modes. The damping characteristic and the resonance frequency of these modes are examined for a wide range of gas pressure and electrostatic voltage loads. The results of the silicon nitride beams and viscoelastic beams are compared. It is found that the intrinsic material loss is the major dissipation mechanism at low pressure for the viscoelastic microbeams, significantly limiting their quality factor. It is also found that while the silicon nitride beams show higher quality factors at the intrinsic and molecular regimes of pressure, due to their low intrinsic loss, their quality factors near atmospheric pressure are lower than those of the viscoelastic microbeams. Further, the higher-order modes of all the beams show much higher quality factors at atmospheric pressure compared to the first mode, which could be promising for operating such resonators in air. Experimental results and finite element model simulations show good agreement for resonance frequency and quality factor for the three studied modes. © 2016 IOP Publishing Ltd.

  5. Two distinct voltage-sensing domains control voltage sensitivity and kinetics of current activation in CaV1.1 calcium channels.

    Science.gov (United States)

    Tuluc, Petronel; Benedetti, Bruno; Coste de Bagneaux, Pierre; Grabner, Manfred; Flucher, Bernhard E

    2016-06-01

    Alternative splicing of the skeletal muscle CaV1.1 voltage-gated calcium channel gives rise to two channel variants with very different gating properties. The currents of both channels activate slowly; however, insertion of exon 29 in the adult splice variant CaV1.1a causes an ∼30-mV right shift in the voltage dependence of activation. Existing evidence suggests that the S3-S4 linker in repeat IV (containing exon 29) regulates voltage sensitivity in this voltage-sensing domain (VSD) by modulating interactions between the adjacent transmembrane segments IVS3 and IVS4. However, activation kinetics are thought to be determined by corresponding structures in repeat I. Here, we use patch-clamp analysis of dysgenic (CaV1.1 null) myotubes reconstituted with CaV1.1 mutants and chimeras to identify the specific roles of these regions in regulating channel gating properties. Using site-directed mutagenesis, we demonstrate that the structure and/or hydrophobicity of the IVS3-S4 linker is critical for regulating voltage sensitivity in the IV VSD, but by itself cannot modulate voltage sensitivity in the I VSD. Swapping sequence domains between the I and the IV VSDs reveals that IVS4 plus the IVS3-S4 linker is sufficient to confer CaV1.1a-like voltage dependence to the I VSD and that the IS3-S4 linker plus IS4 is sufficient to transfer CaV1.1e-like voltage dependence to the IV VSD. Any mismatch of transmembrane helices S3 and S4 from the I and IV VSDs causes a right shift of voltage sensitivity, indicating that regulation of voltage sensitivity by the IVS3-S4 linker requires specific interaction of IVS4 with its corresponding IVS3 segment. In contrast, slow current kinetics are perturbed by any heterologous sequences inserted into the I VSD and cannot be transferred by moving VSD I sequences to VSD IV. Thus, CaV1.1 calcium channels are organized in a modular manner, and control of voltage sensitivity and activation kinetics is accomplished by specific molecular mechanisms

  6. Evaluation influence of machining parameters on shape form errors in turning of machine parts clamped in the chuck with adaptive jaws

    Directory of Open Access Journals (Sweden)

    I.V. Lutsiv

    2017-12-01

    Full Text Available The paper deals with the derivation problem of the dependence of machine part geometric form deviation in cross section area on clamping diameter as well as cutting speed, feed and cutting depth in semi finish machining. The analysis of single factor circular deviation dependences on machining conditions values is performed. Using the special software application package the laboratory conditions experiment results are analyzed. The dispersion analysis including options for main linear and quadratic effects evaluation is given and the simplification model of experiment results is obtained. It presents the evaluation empiric dependence of cutting conditions and clamping diameter influence on shape error forming (dynamic error. It is found that to obtain the necessary form accuracy in machining with lathe chuck equipped with the adaptive clamping jaws it is desirable to control the most statistically significant factors that actually are the cutting depth and feed.

  7. Structural consideration for hot and cold pipe clamps in LMFBR applications

    International Nuclear Information System (INIS)

    Anderson, M.J.; Huang, S.N.; Kappauf, H.; Wagner, S.E.; Wirtz, K.H.

    1983-01-01

    A series of analytical studies are described which evaluate stress levels induced in a 600 mm high temperature, thin-wall sodium pipeline by two alternate clamp designs. The first design consists of a band mounted directly on the pipe and is called the hot clamp. The second design consists of a band mounted using insulation standoffs and is called the cold clamp. Pipe stress levels induced by transient thermal dead weight and seismic loads are discussed. Pipe stress levels and system dynamic spring rates are presented. Procedures utilized to combine clamp induced pipe stress with other short and long term pipe system stresses are detailed. Recommendations for practical application in LMFBR pipe systems are made

  8. Structural considerations for hot and cold pipe clamps in LMFBR applications

    International Nuclear Information System (INIS)

    Anderson, M.J.; Huang, S.N.; Wagner, S.E.; Kappauf, H.; Wirtz, K.H.

    1983-01-01

    A series of analytical studies are described which evaluate stress levels induced in a 600 mm high temperature, thin-wall sodium pipeline by two alternate clamp designs. The first design consists of a band mounted directly on the pipe and is called the hot clamp. The second design consists of a band mounted using insulation standoffs and is called the cold clamp. Pipe stress levels induced by transient thermal dead weight and seismic loads are discussed. Pipe stress levels and system dynamic spring rates are presented. Procedures utilized to combine clamp induced pipe stress with other short and long term pipe system stresses are detailed. Recommendations for practical application in LMFBR pipe systems are made

  9. Investigation of the Dynamics of a Clamped-Clamped Microbeam Near the Third Mode Using a Partial Electrode

    KAUST Repository

    Masri, Karim M.

    2014-08-17

    We present an investigation of the dynamics of a clamped-clamped microbeam excited electrostatically near its third mode. To maximize the response at the third mode, a partial electrode configuration is utilized. A multi-mode Galerkin method is used to develop a reduced order model (ROM) of the beam. A shooting method to find the periodic motion is utilized to generate frequency response curves. The curves show hardenining behavior and dynamic pull-in. We show that the dynamic amplitude of the partial configuration is higher than that of a full electrode configuration. These results are promising for the use of higher-order modes for mass detection and for ultra sensitive resonant sensors.

  10. Investigation of the Dynamics of a Clamped-Clamped Microbeam Near the Third Mode Using a Partial Electrode

    KAUST Repository

    Masri, Karim M.; Younis, Mohammad I.

    2014-01-01

    We present an investigation of the dynamics of a clamped-clamped microbeam excited electrostatically near its third mode. To maximize the response at the third mode, a partial electrode configuration is utilized. A multi-mode Galerkin method is used to develop a reduced order model (ROM) of the beam. A shooting method to find the periodic motion is utilized to generate frequency response curves. The curves show hardenining behavior and dynamic pull-in. We show that the dynamic amplitude of the partial configuration is higher than that of a full electrode configuration. These results are promising for the use of higher-order modes for mass detection and for ultra sensitive resonant sensors.

  11. Combined Triplex/Duplex Invasion of Double-Stranded DNA by "Tail-Clamp" Peptide Nucleic Acid

    DEFF Research Database (Denmark)

    Bentin, Thomas; Larsen, H. J.; Nielsen, Peter E.

    2003-01-01

    as determined by T-m measurements. Binding to double-stranded (ds) DNA occurred by combined triplex and duplex invasion as analyzed by permanganate probing. Furthermore, C-50 measurements revealed that tail-clamp PNAs consistently bound the dsDNA target more efficiently, and kinetics experiments revealed...

  12. High voltage engineering

    CERN Document Server

    Rizk, Farouk AM

    2014-01-01

    Inspired by a new revival of worldwide interest in extra-high-voltage (EHV) and ultra-high-voltage (UHV) transmission, High Voltage Engineering merges the latest research with the extensive experience of the best in the field to deliver a comprehensive treatment of electrical insulation systems for the next generation of utility engineers and electric power professionals. The book offers extensive coverage of the physical basis of high-voltage engineering, from insulation stress and strength to lightning attachment and protection and beyond. Presenting information critical to the design, selec

  13. Simulation and experiment of a YBCO SMES prototype in voltage sag compensation

    International Nuclear Information System (INIS)

    Zhu Jiahui; Yuan Weijia; Coombs, T.A.; Ming, Q.

    2011-01-01

    Research highlights: → YBCO conductors are used in SMES. → The SMES is successfully used to compensate voltage sag by both simulation and experiment. → A new control strategy for the power converter in the SMES. - Abstract: This paper gives a introduction of a SMES unit using 2G HTS wires. A complete SMES system including both superconducting coils and control circuit has been designed to operate at 77 K. Three single-phase H-bridge converters have been used in the control circuit. A loop control signal is sent out by using 32 fixed point Digital Signal Processor (DSP). The complete circuit has been both modelled in simulation and built experimentally. The results validate that this SMES successfully compensates a voltage sag in a power system.

  14. Simulation and experiment of a YBCO SMES prototype in voltage sag compensation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Jiahui, E-mail: zhujiahui@epri.sgcc.com.c [China Electric Power Research Institute, No. 15 Xiaoying Rd(E), Qinghe, Beijing 100192 (China); Yuan Weijia; Coombs, T.A. [Electrical Engineering Division, Engineering Department, University of Cambridge, CB3 0FA (United Kingdom); Ming, Q. [China Electric Power Research Institute, No. 15 Xiaoying Rd(E), Qinghe, Beijing 100192 (China)

    2011-03-15

    Research highlights: {yields} YBCO conductors are used in SMES. {yields} The SMES is successfully used to compensate voltage sag by both simulation and experiment. {yields} A new control strategy for the power converter in the SMES. - Abstract: This paper gives a introduction of a SMES unit using 2G HTS wires. A complete SMES system including both superconducting coils and control circuit has been designed to operate at 77 K. Three single-phase H-bridge converters have been used in the control circuit. A loop control signal is sent out by using 32 fixed point Digital Signal Processor (DSP). The complete circuit has been both modelled in simulation and built experimentally. The results validate that this SMES successfully compensates a voltage sag in a power system.

  15. 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.

  16. Scanning electron microscope/energy dispersive x ray analysis of impact residues on LDEF tray clamps

    Science.gov (United States)

    Bernhard, Ronald P.; Durin, Christian; Zolensky, Michael E.

    1992-01-01

    To better understand the nature of particulates in low-Earth orbit (LEO), and their effects on spacecraft hardware, we are analyzing residues found in impacts on the Long Duration Exposure Facility (LDEF) tray clamps. LDEF experiment trays were held in place by 6 to 8 chromic-anodized aluminum (6061-T6) clamps that were fastened to the spacecraft frame using three stainless steel hex bolts. Each clamp exposed an area of approximately 58 sq cm (4.8 cm x 12.7 cm x .45 cm, minus the bolt coverage). Some 337 out of 774 LDEF tray clamps were archived at JSC and are available through the Meteoroid & Debris Special Investigation Group (M&D SIG). Optical scanning of clamps, starting with Bay/Row A01 and working toward H25, is being conducted at JSC to locate and document impacts as small as 40 microns. These impacts are then inspected by Scanning Electron Microscopy/Energy Dispersive X-ray Analysis (SEM/EDXA) to select those features which contain appreciable impact residue material. Based upon the composition of projectile remnants, and using criteria developed at JSC, we have made a preliminary discrimination between micrometeoroid and space debris residue-containing impact features. Presently, 13 impacts containing significant amounts of unmelted and semi-melted micrometeoritic residues were forwarded to Centre National d'Etudes Spatiales (CNES) in France. At the CNES facilities, the upgraded impacts were analyzed using a JEOL T330A SEM equipped with a NORAN Instruments, Voyager X-ray Analyzer. All residues were quantitatively characterized by composition (including oxygen and carbon) to help understand interplanetary dust as possibly being derived from comets and asteroids.

  17. Control Strategy of Two Capacitor Voltages for Separate MPPTs in Photovoltaic Systems Using Neutral-Point-Clamped Inverters

    DEFF Research Database (Denmark)

    Choi, Ui-Min; Blaabjerg, Frede; Lee, Kyo-Beum

    2015-01-01

    The centralized topology with three-level inverters are widely used in photovoltaic (PV) systems due to their less installation costs and complexity. However, the common maximum power point tracking (MPPT) is a disadvantage of the centralized topology particularly under the partial shading...... and panel mismatch conditions. In this system, if PV modules are separately connected to the split capacitor voltage, the MPPT efficiency can be improved by the proposed control strategy. By the proposed method, the two capacitor voltages can be controlled asymmetrically to perform the separate MPPTs...... of each PV module connected to separate capacitors. The outputs can be generated without distortion even if two capacitors are asymmetrically regulated. Simulation and experimental results verify the validity and feasibility of the proposed methods....

  18. COMPARISON OF EARLY AND DELAYED UMBILICAL CORD CLAMPING IN THE THIRD STAGE OF LABOUR

    Directory of Open Access Journals (Sweden)

    Tamara Serdinšek

    2015-09-01

    Full Text Available Background: Umbilical cord clamping in the third stage of labour is still controversial. Early cord clamping is defined as clamping at 10, 15, 30 or 60 seconds after delivery and delayed as clamping after 60 seconds or at 2-5 minutes after delivery, when the cord stops pulsating or when the placenta is visible within the birth canal. Early clamping is one of the three components of active management of the third stage of labour, which has been used widely in modern obstetrics during the last century. However, in some northern European countries, various parts of the USA and Canada and in developing countries physiological management is preferred.Conclusions: After publication of several trials describing advantages of delayed clamping, this has recently been progressively replacing early clamping. The most important advantages of delayed cord clamping are higher haemoglobin and ferritin levels, higher iron stores, lower incidence of iron deficiency anaemia, better cardiopulmonary adaptation, lower rate of respiratory distress syndrome, and longer duration of early breastfeeding in term neonates, while there is no increase in the incidence of postpartum haemorrhage. Delayed clamping seems to bring some advantages for preterm neonates as well. However, caution is still advised because of the potential adverse effects, especially polycythaemia with hyperviscosity, hyperbilirubinaemia and respiratory distress.

  19. Different methods of hilar clamping during partial nephrectomy: Impact on renal function.

    Science.gov (United States)

    Lee, Jeong Woo; Kim, Hwanik; Choo, Minsoo; Park, Yong Hyun; Ku, Ja Hyeon; Kim, Hyeon Hoe; Kwak, Cheol

    2014-03-01

    To evaluate the impact of different hilar clamping methods on changes in renal function after partial nephrectomy. We analyzed the clinical data of 369 patients who underwent partial nephrectomy for a single renal tumor of size ≤4.0 cm and a normal contralateral kidney. Patients were separated into three groups depending on hilar clamping method: non-clamping, cold ischemia and warm ischemia. Estimated glomerular filtration rate was examined at preoperative, nadir and 1 year postoperatively. Percent change in estimated glomerular filtration rate was used as the parameter to assess the renal functional outcome. Percent change in nadir estimated glomerular filtration rate in the non-clamping group was significantly less compared with the cold ischemia and warm ischemia groups (P hilar clamping (both warm ischemia and cold ischemia) were significantly associated with percent change in nadir estimated glomerular filtration rate, but not in 1-year estimated glomerular filtration rate. Non-clamping partial nephrectomy results in a lower percent change in nadir estimated glomerular filtration rate, whereas it carries an estimated glomerular filtration rate change at 1 year that is similar to partial nephrectomy with cold ischemia and warm ischemia. Cold ischemia and warm ischemia provide a similar effect on renal function. Therefore, when hilar clamping is required, minimization of ischemia time is necessary. © 2013 The Japanese Urological Association.

  20. Automated sampling and data processing derived from biomimetic membranes

    DEFF Research Database (Denmark)

    Perry, Mark; Vissing, Thomas; Boesen, P.

    2009-01-01

    data processing software to analyze and organize the large amounts of data generated. In this work, we developed an automated instrumental voltage clamp solution based on a custom-designed software controller application (the WaveManager), which enables automated on-line voltage clamp data acquisition...... applicable to long-time series experiments. We designed another software program for off-line data processing. The automation of the on-line voltage clamp data acquisition and off-line processing was furthermore integrated with a searchable database (DiscoverySheet (TM)) for efficient data management......Recent advances in biomimetic membrane systems have resulted in an increase in membrane lifetimes from hours to days and months. Long-lived membrane systems demand the development of both new automated monitoring equipment capable of measuring electrophysiological membrane characteristics and new...

  1. Push-pull with recovery stage high-voltage DC converter for PV solar generator

    Science.gov (United States)

    Nguyen, The Vinh; Aillerie, Michel; Petit, Pierre; Pham, Hong Thang; Vo, Thành Vinh

    2017-02-01

    A lot of systems are basically developed on DC-DC or DC-AC converters including electronic switches such as MOS or bipolar transistors. The limits of efficiency are quickly reached when high output voltages and high input currents are needed. This work presents a new high-efficiency-high-step-up based on push-pull DC-DC converter integrating recovery stages dedicated to smart HVDC distributed architecture in PV solar energy production systems. Appropriate duty cycle ratio assumes that the recovery stage work with parallel charge and discharge to achieve high step-up voltage gain. Besides, the voltage stress on the main switch is reduced with a passive clamp circuit and thus, low on-state resistance Rdson of the main switch can be adopted to reduce conduction losses. Thus, the efficiency of a basic DC-HVDC converter dedicated to renewable energy production can be further improved with such topology. A prototype converter is developed, and experimentally tested for validation.

  2. Operating Experiences of a Loss of Voltage Monitoring Program

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun-Chan [Korea Hydro and Nuclear Power Co. Ltd., Daejeon (Korea, Republic of)

    2015-10-15

    Loss of voltage (LOV) events continue to occur due to inadequate work management and random human errors. On February 26, 2015, regulators analyzed the root causes of LOV events and presented the results for the nuclear industry. Currently, KHNP uses a risk monitoring program, which is named 'LOV Monitor', for LOV prevention during pilot plant outages. This review introduces the operation experiences of LOV Monitor based on the evaluation results of a real event. The operation experiences of LOV Monitor in the pilot plants confirmed that this program could detect and reduce LOV possibilities from scheduling errors such as the simultaneous maintenance of energized trains and de-energized trains considering the physical conditions of the power circuit breakers. However, a maintenance culture that heeds the risk monitoring result must be strengthened in order to obtain substantial effects through applying LOV Monitor to the outage.

  3. The Investigation of the Corrosion Resistance of the Tension Clamps Skl14

    Directory of Open Access Journals (Sweden)

    Marek Pětioký

    2015-05-01

    Full Text Available At the level crossings it is possible to find the problems with the corrosion of the parts of the fastening system. These problems are especially at the rubber level crossings and in the tunnels. As a part of the thesis the problem of the corrosion of the tension clamp Skl14 of the producer Vossloh at the rubber level crossings is examined. For the purposes of the comparison the tension clamps without the corrosion protection and the tension clamps with the corrosion protection KTL were examined. As a first step the corrosion features of the tension clamps Skl14 were solved. The examination was divided into two parts. First part it was the examination according to ČSN EN ISO 9227. The samples of the tension clamps were putted into the corrosion chamber. After 1728 h the results of the corrosion impacts were not satisfied. It was decided for the second step of the examination. It was the immersion in an electrolyte solution. As a result of the paper the corrosion features of the tension clamps without the corrosion protection and with the corrosion protection are compared.

  4. Voltage-dependent gating in a "voltage sensor-less" ion channel.

    Directory of Open Access Journals (Sweden)

    Harley T Kurata

    2010-02-01

    Full Text Available The voltage sensitivity of voltage-gated cation channels is primarily attributed to conformational changes of a four transmembrane segment voltage-sensing domain, conserved across many levels of biological complexity. We have identified a remarkable point mutation that confers significant voltage dependence to Kir6.2, a ligand-gated channel that lacks any canonical voltage-sensing domain. Similar to voltage-dependent Kv channels, the Kir6.2[L157E] mutant exhibits time-dependent activation upon membrane depolarization, resulting in an outwardly rectifying current-voltage relationship. This voltage dependence is convergent with the intrinsic ligand-dependent gating mechanisms of Kir6.2, since increasing the membrane PIP2 content saturates Po and eliminates voltage dependence, whereas voltage activation is more dramatic when channel Po is reduced by application of ATP or poly-lysine. These experiments thus demonstrate an inherent voltage dependence of gating in a "ligand-gated" K+ channel, and thereby provide a new view of voltage-dependent gating mechanisms in ion channels. Most interestingly, the voltage- and ligand-dependent gating of Kir6.2[L157E] is highly sensitive to intracellular [K+], indicating an interaction between ion permeation and gating. While these two key features of channel function are classically dealt with separately, the results provide a framework for understanding their interaction, which is likely to be a general, if latent, feature of the superfamily of cation channels.

  5. Low voltage powering of on-detector electronics for HL-LHC experiments upgrades

    CERN Document Server

    Bobillier, Vincent; Vasey, Francois; Karmakar, Sabyasachi; Maity, Manas; Roy, Subhasish; Kundu, Tapas Kumar

    2018-01-01

    All LHC experiments will be upgraded during the next LHC long shutdowns (LS2 and LS3). The increase in resolution and luminosity and the use of more advanced CMOS technology nodes typically implies higher current consumption of the on-detector electronics. In this context, and in view of limiting the cable voltage drop, point-of-load DC-DC converters will be used on detector. This will have a direct impact on the existing powering scheme, implying new AC-DC and/or DC-DC stages as well as changes in the power cabling infrastructure. This paper presents the first results obtained while evaluating different LV powering schemes and distribution layouts for HL-LHC trackers. The precise low voltage power source requirements are being assessed and understood using the CMS tracker upgrade as a use-case.

  6. 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...

  7. Four- year thyroidectomy procedures: Ligasure Vs. clamp & tie

    Directory of Open Access Journals (Sweden)

    Pazoki AR

    2010-01-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: The electrothermal bipolar vessel sealing system is an adjunct to the hemostatic technique, which has been successfully used in many abdominal operation, recently made available to thyroid surgery. The purpose of this was compare the outcomes of new hemostatic technique with traditional method of clamp and tie."n"nMethods: In this retrospective cross-sectional study has been done in surgery's wards of Milad & Rasul- Akram hospitals in Tehran, Iran. During three- year period between 2005-2008 all patients with different kind of pathology that need operation were assessed. Time duration of surgery and hospital stay and post surgery complication in two group, ligasure (n=45 and clamp & tie (n=145 were compared with each others."n"nResults: No difference was seen between two groups in time duration of surgery. Significant difference was seen in hospital stay and complications of surgery. Time of operation in Ligasure group was 132/22 minute and in clamp and tie group was 130/10 minute. There was found significant difference in duration of hospital stay and postoperative complication. Hypocalcemia were seen in two and 24 cases in Ligasure and Clamp & Tie group, respectively (p<0.05. Hospital stay was 2

  8. Prepulse suppression and allowable prepulse voltage in Z-pinch experiments

    International Nuclear Information System (INIS)

    Xia Minghe; Xie Weiping; Li Hongtao

    2004-01-01

    The causes of prepulse origin in pulse power machine especially in Blumlein pulser are analyzed in this paper. A method that can reduce the prepulse by an inductance between Marx and zero voltage node has been presented while a calculation example used Pspice is provided. The prepulse switches can be used to reduce the prepulse effects in many fields. The prepulse requests for wire arrays in Z-pinch experiments are analyzed and explained by means of specific reaction quantity and vaporization heat, the results of the calculations are similar. In fact, the results of experiments indicate that the energy deposited in the wires is sufficient to bring the aluminium wires to partial or total vaporization. Because the value of prepulse current is larger than that of calculation, this indicates the calculation method is right

  9. Ventilatory effects of hypercapnic end-tidal PCO2 clamps during aerobic exercise of varying intensity.

    Science.gov (United States)

    Essfeld, D; Hoffmann, U; Stegemann, J

    1990-01-01

    Nine subjects performed a sequence of sustained and randomised changes between 40 W and 100 W on a cycle ergometer while the end-tidal PO2 was kept close to 17.3 kPa (130 mm Hg) by means of a dynamic forcing technique (reference experiment). In a second series inspiratory CO2 was additionally manipulated so as to hold end-tidal PCO2 (PETCO2) near 6.5 kPa (49 mm Hg; 'CO2-clamp' experiment). By this forcing PETCO2 oscillations were attenuated and more evenly distributed over the frequency range. Ventilation (VT) responded to this manoeuvre with an upward trend that could not be ascribed to a slow CO2-response component, changes in metabolic rate or a dissociation of end-tidal and arterial PCO2. VT differences between reference and CO2-clamp experiments were abolished within a 3-min period following the termination of the external CO2 control. The present results suggest that the CO2-H+ stimulus plays a major role in adjusting ventilation when exercise intensity is decreased. The underlying CO2 effect appears to be neither additive nor bi-directionally symmetrical.

  10. Improved DNA clamps by stacking to adjacent nucleobases

    DEFF Research Database (Denmark)

    Fatthalla, M.I.; Pedersen, Erik Bjerregaard

    2012-01-01

    Three or four aromatic rings interconnected by acetylene bridges form a stiff conjugated system with sufficient conformational freedom to make it useful to link together the two strands of a DNA clamp. Upon targeting a ssDNA, the conformational flexibility allows better stacking of the linker...... to the underlying non-planar base triplet in the formed triplex. This type of triplexes has a substantially higher thermal melting temperature which can be further improved by inserting locked nucleic acids (LNAs) in the Hoogsteen part of the clamp. An extremely high sensitivity to mismatches is observed...

  11. Simulation of rectifier voltage malfunction on OWECS, four-level converter, HVDC light link: Smart grid context tool

    International Nuclear Information System (INIS)

    Seixas, M.; Melício, R.; Mendes, V.M.F.

    2015-01-01

    Highlights: • Floating offshore wind turbine in deep water. • DC link and voltage malfunction. • Converter topology considered is four-level. • Controllers are based on fractional-order. • Smart grid context. - Abstract: This paper presents a model for the simulation of an offshore wind system having a rectifier input voltage malfunction at one phase. The offshore wind system model comprises a variable-speed wind turbine supported on a floating platform, equipped with a permanent magnet synchronous generator using full-power four-level neutral point clamped converter. The link from the offshore floating platform to the onshore electrical grid is done through a light high voltage direct current submarine cable. The drive train is modeled by a three-mass model. Considerations about the smart grid context are offered for the use of the model in such a context. The rectifier voltage malfunction domino effect is presented as a case study to show capabilities of the model

  12. Formal Design Review Foot Clamp Modification

    International Nuclear Information System (INIS)

    OTEN, T.C.

    2000-01-01

    This report documents the Design Review performed for the foot clamp modification. The report documents the acceptability of the design, identifies the documents that were reviewed, the scope of the review and the members of the review team

  13. Integrative Approach with Electrophysiological and Theoretical Methods Reveals a New Role of S4 Positively Charged Residues in PKD2L1 Channel Voltage-Sensing.

    Science.gov (United States)

    Numata, Tomohiro; Tsumoto, Kunichika; Yamada, Kazunori; Kurokawa, Tatsuki; Hirose, Shinichi; Nomura, Hideki; Kawano, Mitsuhiro; Kurachi, Yoshihisa; Inoue, Ryuji; Mori, Yasuo

    2017-08-29

    Numerical model-based simulations provide important insights into ion channel gating when experimental limitations exist. Here, a novel strategy combining numerical simulations with patch clamp experiments was used to investigate the net positive charges in the putative transmembrane segment 4 (S4) of the atypical, positively-shifted voltage-dependence of polycystic kidney disease 2-like 1 (PKD2L1) channel. Charge-neutralising mutations (K452Q, K455Q and K461Q) in S4 reduced gating charges, positively shifted the Boltzmann-type activation curve [i.e., open probability (P open )-V curve] and altered the time-courses of activation/deactivation of PKD2L1, indicating that this region constitutes part of a voltage sensor. Numerical reconstruction of wild-type (WT) and mutant PKD2L1-mediated currents necessitated, besides their voltage-dependent gating parameters, a scaling factor that describes the voltage-dependence of maximal conductance, G max . Subsequent single-channel conductance (γ) measurements revealed that voltage-dependence of G max in WT can be explained by the inward-rectifying property of γ, which is greatly changed in PKD2L1 mutants. Homology modelling based on PKD2 and Na V Ab structures suggest that such voltage dependence of P open and γ in PKD2L1 could both reflect the charged state of the S4 domain. The present conjunctive experimental and theoretical approaches provide a framework to explore the undetermined mechanism(s) regulating TRP channels that possess non-classical voltage-dependent properties.

  14. The supply voltage apparatus of the CUORE experiment

    Energy Technology Data Exchange (ETDEWEB)

    Arnaboldi, C.; Baú, A.; Carniti, P.; Cassina, L.; Giachero, A.; Gotti, C.; Maino, M.; Passerini, A. [INFN, Sezione di Milano Bicocca - Istituto Nazionale di Fisica Nucleare, Piazza della Scienza 3 Milano (Italy); Università di Milano Bicocca - Dipartimento di Fisica, Piazza della Scienza 3 Milano (Italy); Pessina, G., E-mail: Pessina@mib.infn.it [INFN, Sezione di Milano Bicocca - Istituto Nazionale di Fisica Nucleare, Piazza della Scienza 3 Milano (Italy); Università di Milano Bicocca - Dipartimento di Fisica, Piazza della Scienza 3 Milano (Italy)

    2016-07-11

    The Electronics system of experiments for the study of rare decays, such as the neutrino-less double beta decay, must be very stable over very long expected runs. We introduce our solution for the power supply of such an experiment, CUORE. In this case the power supply chain consists of a series of ACDCs, followed by DCDCs and then Linear Regulators. We emphasize here our approach to the DCDC regulation system that was designed with a complete rejection of the switching noise, across 100 MHz bandwidth. In the experimental layout the DCDC will be located far from the very front-end, with long connecting cables (10 m). We introduced our very simple and safe solution to prevent huge over-voltages, due to the energy stored in the inductance of the cables, generated after the release of accidental short circuits, so avoiding destructive effects. Some micro-controllers are present on every board and take care of the DCDC operation. These micro-controllers are managed from the control room, via CAN BUS protocol coupled via optical fibres. CUORE is an array of 1000 cryogenic detectors that will need 30 of our DCDCs.

  15. The supply voltage apparatus of the CUORE experiment

    Science.gov (United States)

    Arnaboldi, C.; Baú, A.; Carniti, P.; Cassina, L.; Giachero, A.; Gotti, C.; Maino, M.; Passerini, A.; Pessina, G.

    2016-07-01

    The Electronics system of experiments for the study of rare decays, such as the neutrino-less double beta decay, must be very stable over very long expected runs. We introduce our solution for the power supply of such an experiment, CUORE. In this case the power supply chain consists of a series of ACDCs, followed by DCDCs and then Linear Regulators. We emphasize here our approach to the DCDC regulation system that was designed with a complete rejection of the switching noise, across 100 MHz bandwidth. In the experimental layout the DCDC will be located far from the very front-end, with long connecting cables (10 m). We introduced our very simple and safe solution to prevent huge over-voltages, due to the energy stored in the inductance of the cables, generated after the release of accidental short circuits, so avoiding destructive effects. Some micro-controllers are present on every board and take care of the DCDC operation. These micro-controllers are managed from the control room, via CAN BUS protocol coupled via optical fibres. CUORE is an array of 1000 cryogenic detectors that will need 30 of our DCDCs.

  16. The supply voltage apparatus of the CUORE experiment

    International Nuclear Information System (INIS)

    Arnaboldi, C.; Baú, A.; Carniti, P.; Cassina, L.; Giachero, A.; Gotti, C.; Maino, M.; Passerini, A.; Pessina, G.

    2016-01-01

    The Electronics system of experiments for the study of rare decays, such as the neutrino-less double beta decay, must be very stable over very long expected runs. We introduce our solution for the power supply of such an experiment, CUORE. In this case the power supply chain consists of a series of ACDCs, followed by DCDCs and then Linear Regulators. We emphasize here our approach to the DCDC regulation system that was designed with a complete rejection of the switching noise, across 100 MHz bandwidth. In the experimental layout the DCDC will be located far from the very front-end, with long connecting cables (10 m). We introduced our very simple and safe solution to prevent huge over-voltages, due to the energy stored in the inductance of the cables, generated after the release of accidental short circuits, so avoiding destructive effects. Some micro-controllers are present on every board and take care of the DCDC operation. These micro-controllers are managed from the control room, via CAN BUS protocol coupled via optical fibres. CUORE is an array of 1000 cryogenic detectors that will need 30 of our DCDCs.

  17. Gabapentin Modulates HCN4 Channel Voltage-Dependence

    Directory of Open Access Journals (Sweden)

    Han-Shen Tae

    2017-08-01

    Full Text Available Gabapentin (GBP is widely used to treat epilepsy and neuropathic pain. There is evidence that GBP can act on hyperpolarization-activated cation (HCN channel-mediated Ih in brain slice experiments. However, evidence showing that GBP directly modulates HCN channels is lacking. The effect of GBP was tested using two-electrode voltage clamp recordings from human HCN1, HCN2, and HCN4 channels expressed in Xenopus oocytes. Whole-cell recordings were also made from mouse spinal cord slices targeting either parvalbumin positive (PV+ or calretinin positive (CR+ inhibitory neurons. The effect of GBP on Ih was measured in each inhibitory neuron population. HCN4 expression was assessed in the spinal cord using immunohistochemistry. When applied to HCN4 channels, GBP (100 μM caused a hyperpolarizing shift in the voltage of half activation (V1/2 thereby reducing the currents. Gabapentin had no impact on the V1/2 of HCN1 or HCN2 channels. There was a robust increase in the time to half activation for HCN4 channels with only a small increase noted for HCN1 channels. Gabapentin also caused a hyperpolarizing shift in the V1/2 of Ih measured from HCN4-expressing PV+ inhibitory neurons in the spinal dorsal horn. Gabapentin had minimal effect on Ih recorded from CR+ neurons. Consistent with this, immunohistochemical analysis revealed that the majority of CR+ inhibitory neurons do not express somatic HCN4 channels. In conclusion, GBP reduces HCN4 channel-mediated currents through a hyperpolarized shift in the V1/2. The HCN channel subtype selectivity of GBP provides a unique tool for investigating HCN4 channel function in the central nervous system. The HCN4 channel is a candidate molecular target for the acute analgesic and anticonvulsant actions of GBP.

  18. Prediction of breakdown voltages in novel gases for high voltage insulation

    International Nuclear Information System (INIS)

    Koch, M.

    2015-01-01

    This thesis submitted to the Swiss Federal Institute of Technology ETH in Zurich examines the use of sulphur hexafluoride (SF_6) and similar gases as important insulation media for high voltage equipment. Due to its superior insulation properties, SF_6 is widely used in gas-insulated switchgear. However, the gas also has a very high global warming potential and the content of SF_6 in the atmosphere is constantly increasing. The search for new insulation gases using classical breakdown experiments is discussed. A model for SF_6 based on the stepped leader model is described. This calculates the breakdown voltages in arbitrary electrode configurations and under standard voltage waveforms. Thus, the thesis provides a method for the prediction of breakdown voltages of arbitrary field configurations under standard voltage waveforms for gases with electron-attaching properties. With this, further gases can be characterized for usage as high voltage insulation media

  19. Molecular mechanism of DNA replication-coupled inactivation of the initiator protein in Escherichia coli: interaction of DnaA with the sliding clamp-loaded DNA and the sliding clamp-Hda complex.

    Science.gov (United States)

    Su'etsugu, Masayuki; Takata, Makoto; Kubota, Toshio; Matsuda, Yusaku; Katayama, Tsutomu

    2004-06-01

    In Escherichia coli, the ATP-DnaA protein initiates chromosomal replication. After the DNA polymerase III holoenzyme is loaded on to DNA, DnaA-bound ATP is hydrolysed in a manner depending on Hda protein and the DNA-loaded form of the DNA polymerase III sliding clamp subunit, which yields ADP-DnaA, an inactivated form for initiation. This regulatory DnaA-inactivation represses extra initiation events. In this study, in vitro replication intermediates and structured DNA mimicking replicational intermediates were first used to identify structural prerequisites in the process of DnaA-ATP hydrolysis. Unlike duplex DNA loaded with sliding clamps, primer RNA-DNA heteroduplexes loaded with clamps were not associated with DnaA-ATP hydrolysis, and duplex DNA provided in trans did not rescue this defect. At least 40-bp duplex DNA is competent for the DnaA-ATP hydrolysis when a single clamp was loaded. The DnaA-ATP hydrolysis was inhibited when ATP-DnaA was tightly bound to a DnaA box-bearing oligonucleotide. These results imply that the DnaA-ATP hydrolysis involves the direct interaction of ATP-DnaA with duplex DNA flanking the sliding clamp. Furthermore, Hda protein formed a stable complex with the sliding clamp. Based on these, we suggest a mechanical basis in the DnaA-inactivation that ATP-DnaA interacts with the Hda-clamp complex with the aid of DNA binding. Copyright Blackwell Publishing Limited

  20. RESULTS OF TESTS OF LIGHTNING-RODS WITH UNIVERSAL CLAMPS BY THE APERIODIC IMPULSES OF CURRENT OF ARTIFICIAL LIGHTNING WITH THE PEAK-TEMPORAL PARAMETERS RATIONED ON FOREIGN STANDARDS

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2015-06-01

    Full Text Available Purpose. Test in obedience to the requirements of row of operating foreign standards of round metallic lightning-rods with the flat metallic universal clamps of the special type on firmness to direct action of аperiodic impulses of current of temporal form 10/350 μs by amplitude of 50 кА (N− class and 100 кА (H− class. Methodology. The order of leadthrough of these tests is certain the followings normative documents: International IEC 62305-1: 2010, Russian national GOST R IEC 62305-1-2010 and German national DIN EN 50164-1:2008 Standards. Results. Conducted on a powerful high-voltage pulsed current of artificial linear lightning with the peak-temporal parameters and admittances of test rationed on the indicated foreign standards rationed that all of the lightning-rods tested in collection with universal clamps, isolating holders and ceramic elements of roof of technical building were survive electrodynamics and electrothermal action of in-use single short blow of an artificial storm digit. Originality. First in domestic practice the similar model tests of lightning-rods are conducted with universal clamps, executed from different explorer materials, on firmness to flowing to on by it the indicated large impulsive currents of artificial lightning. Practical value. Real firmness to lightning of round copper and zincked steel lightning-rods is certain with the flat copper, zincked steel and non-rusting steel universal clamps of the special execution.

  1. Clamp wins pipe repair prize

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2001-04-01

    This paper describes the permanent pipeline repair system, developed by Tekmar, which is powered by seawater hydraulics and is easily installed and tested by any workclass remotely operated vehicle (rov). Details are given of the two main components of the system, namely, the diverless high pressure split repair clamp and the rov-operated tool to install it.

  2. Contribution to high voltage matrix switches reliability

    International Nuclear Information System (INIS)

    Lausenaz, Yvan

    2000-01-01

    Nowadays, power electronic equipment requirements are important, concerning performances, quality and reliability. On the other hand, costs have to be reduced in order to satisfy the market rules. To provide cheap, reliability and performances, many standard components with mass production are developed. But the construction of specific products must be considered following these two different points: in one band you can produce specific components, with delay, over-cost problems and eventuality quality and reliability problems, in the other and you can use standard components in a adapted topologies. The CEA of Pierrelatte has adopted this last technique of power electronic conception for the development of these high voltage pulsed power converters. The technique consists in using standard components and to associate them in series and in parallel. The matrix constitutes high voltage macro-switch where electrical parameters are distributed between the synchronized components. This study deals with the reliability of these structures. It brings up the high reliability aspect of MOSFETs matrix associations. Thanks to several homemade test facilities, we obtained lots of data concerning the components we use. The understanding of defects propagation mechanisms in matrix structures has allowed us to put forwards the necessity of robust drive system, adapted clamping voltage protection, and careful geometrical construction. All these reliability considerations in matrix associations have notably allowed the construction of a new matrix structure regrouping all solutions insuring reliability. Reliable and robust, this product has already reaches the industrial stage. (author) [fr

  3. Natural Vibration Analysis of Clamped Rectangular Orthotropic Plates

    Science.gov (United States)

    dalaei, m.; kerr, a. d.

    The natural vibrations of clamped rectangular orthotropic plates are analyzed using the extended Kantorovich method. The developed iterative scheme converges very rapidly to the final result. The obtained natural frequencies are evaluated for a square plate made of Kevlar 49 Epoxy and the obtained results are compared with those published by Kanazawa and Kawai, and by Leissa. The agreement was found to be very close. As there are no exact analytical solutions for clamped rectangular plates, the generated closed form expression for the natural modes, and the corresponding natural frequencies, are very suitable for use in engineering analyses.

  4. Effect of non-ideal clamping shape on the resonance frequencies of silicon nanocantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Guillon, Samuel; Saya, Daisuke; Mazenq, Laurent; Nicu, Liviu [CNRS, LAAS, 7 Avenue du Colonel Roche, F-31077 Toulouse Cedex 4 (France); Perisanu, Sorin; Vincent, Pascal [LPMCN, Universite Claude Bernard Lyon 1 et CNRS, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex (France); Lazarus, Arnaud; Thomas, Olivier, E-mail: sguillon@laas.fr [Structural Mechanics and Coupled Systems Laboratory, Conservatoire National des Arts et Metiers, 2 rue Conte, 75003 Paris (France)

    2011-06-17

    In this paper, we investigate the effects of non-ideal clamping shapes on the dynamic behavior of silicon nanocantilevers. We fabricated silicon nanocantilevers using silicon on insulator (SOI) wafers by employing stepper ultraviolet (UV) lithography, which permits a resolution of under 100 nm. The nanocantilevers were driven by electrostatic force inside a scanning electron microscope (SEM). Both lateral and out-of-plane resonance frequencies were visually detected with the SEM. Next, we discuss overhanging of the cantilever support and curvature at the clamping point in the silicon nanocantilevers, which generally arises in the fabrication process. We found that the fundamental out-of-plane frequency of a realistically clamped cantilever is always lower than that for a perfectly clamped cantilever, and depends on the cantilever width and the geometry of the clamping point structure. Using simulation with the finite-elements method, we demonstrate that this discrepancy is attributed to the particular geometry of the clamping point (non-zero joining curvatures and a flexible overhanging) that is obtained in the fabrication process. The influence of the material orthotropy is also investigated and is shown to be negligible.

  5. Clamped end conditions and cross section deformation in the finite element absolute nodal coordinate formulation

    International Nuclear Information System (INIS)

    Hussein, Bassam A.; Weed, David; Shabana, Ahmed A.

    2009-01-01

    In the finite element absolute nodal coordinate formulation (ANCF), the elimination of the relative translations and rotations at a point does not necessarily define a fully clamped joint, particularly in the case of fully parameterized ANCF finite elements that allow for the deformation of the cross section. In this investigation, the formulations and results of two different sets of clamped end conditions that define two different joints are compared. The first joint, called the partially clamped joint, eliminates only the translations and rotations at a point on the cross section. The second joint, called the fully clamped joint, eliminates all the translation, rotation and deformation degrees of freedom at a point on the cross section. The kinematic equations that define the partially and fully clamped joints are developed, and the dynamic equations used in the comparative numerical study presented in this paper are shown. As discussed in this investigation, the fully clamped joint does not allow for the deformation of the cross section at the joint node since the gradient vectors remain orthogonal unit vectors. The partially clamped joint, on the other hand, allows for the deformation of the cross section. Nanson's formula is used as a measure of the deformation of the cross section in the case of the partially clamped joint. A very flexible pendulum that has a rigid body attached to its free end is used to compare the results of the partially and fully clamped joints. The numerical results obtained using this very flexible pendulum example show that, while the type of joint (partially or fully clamped) does not significantly affect the gross reference motion of the system, there are fundamental differences between the two joints since the partially clamped joint allows for the cross section deformations at the joint node

  6. Analysis of whole-cell currents by patch clamp of guinea-pig myenteric neurones in intact ganglia

    Science.gov (United States)

    Rugiero, François; Gola, Maurice; Kunze, Wolf A A; Reynaud, Jean-Claude; Furness, John B; Clerc, Nadine

    2002-01-01

    Whole-cell patch-clamp recordings taken from guinea-pig duodenal myenteric neurones within intact ganglia were used to determine the properties of S and AH neurones. Major currents that determine the states of AH neurones were identified and quantified. S neurones had resting potentials of −47 ± 6 mV and input resistances (Rin) of 713 ± 49 MΩ at voltages ranging from −90 to −40 mV. At more negative levels, activation of a time-independent, caesium-sensitive, inward-rectifier current (IKir) decreased Rin to 103 ± 10 MΩ. AH neurones had resting potentials of −57 ± 4 mV and Rin was 502 ± 27 MΩ. Rin fell to 194 ± 16 MΩ upon hyperpolarization. This decrease was attributable mainly to the activation of a cationic h current, Ih, and to IKir. Resting potential and Rin exhibited a low sensitivity to changes in [K+]o in both AH and S neurones. This indicates that both cells have a low background K+ permeability. The cationic current, Ih, contributed about 20 % to the resting conductance of AH neurones. It had a half-activation voltage of −72 ± 2 mV, and a voltage sensitivity of 8.2 ± 0.7 mV per e-fold change. Ih has relatively fast, voltage-dependent kinetics, with on and off time constants in the range of 50–350 ms. AH neurones had a previously undescribed, low threshold, slowly inactivating, sodium-dependent current that was poorly sensitive to TTX. In AH neurones, the post-action-potential slow hyperpolarizing current, IAHP, displayed large variation from cell to cell. IAHP appeared to be highly Ca2+ sensitive, since its activation with either membrane depolarization or caffeine (1 mm) was not prevented by perfusing the cell with 10 mm BAPTA. We determined the identity of the Ca2+ channels linked to IAHP. Action potentials of AH neurones that were elongated by TEA (10 mm) were similarly shortened and IAHP was suppressed with each of the three Ω-conotoxins GVIA, MVIIA and MVIIC (0.3–0.5 μm), but not with Ω-agatoxin IVA (0.2 μm). There was no

  7. Improving the transient response of a bolt-clamped Langevin transducer using a parallel resistor.

    Science.gov (United States)

    Chang, Kuo Tsi

    2003-08-01

    This paper suggests a parallel resistor to reduce DC time constant and DC response time of the transient response, induced immediately after an AC voltage connected to a bolt-clamped Langevin transducer (BLT) is switched off. An equivalent circuit is first expressed. Then, an open-circuit transient response at the terminals induced by initial states is derived and measured, and thus parameters for losses of the BLT device are estimated by DC and AC time constants of the transient response. Moreover, a driving and measuring system is designed to determine transient response and steady-state responses of the BLT device, and a parallel resistor is connected to the BLT device to reduce the DC time constant. Experimental results indicate that the DC time constant greatly exceeds the AC time constant without the parallel resistor, and greatly decreases from 42 to 1 ms by a 100-kOmega parallel resistor.

  8. Prediction of breakdown voltages in novel gases for high voltage insulation

    Energy Technology Data Exchange (ETDEWEB)

    Koch, M.

    2015-07-01

    This thesis submitted to the Swiss Federal Institute of Technology ETH in Zurich examines the use of sulphur hexafluoride (SF{sub 6}) and similar gases as important insulation media for high voltage equipment. Due to its superior insulation properties, SF{sub 6} is widely used in gas-insulated switchgear. However, the gas also has a very high global warming potential and the content of SF{sub 6} in the atmosphere is constantly increasing. The search for new insulation gases using classical breakdown experiments is discussed. A model for SF{sub 6} based on the stepped leader model is described. This calculates the breakdown voltages in arbitrary electrode configurations and under standard voltage waveforms. Thus, the thesis provides a method for the prediction of breakdown voltages of arbitrary field configurations under standard voltage waveforms for gases with electron-attaching properties. With this, further gases can be characterized for usage as high voltage insulation media.

  9. Role of the Checkpoint Clamp in DNA Damage Response

    Directory of Open Access Journals (Sweden)

    Mihoko Kai

    2013-01-01

    Full Text Available DNA damage occurs during DNA replication, spontaneous chemical reactions, and assaults by external or metabolism-derived agents. Therefore, all living cells must constantly contend with DNA damage. Cells protect themselves from these genotoxic stresses by activating the DNA damage checkpoint and DNA repair pathways. Coordination of these pathways requires tight regulation in order to prevent genomic instability. The checkpoint clamp complex consists of Rad9, Rad1 and Hus1 proteins, and is often called the 9-1-1 complex. This PCNA (proliferating cell nuclear antigen-like donut-shaped protein complex is a checkpoint sensor protein that is recruited to DNA damage sites during the early stage of the response, and is required for checkpoint activation. As PCNA is required for multiple pathways of DNA metabolism, the checkpoint clamp has also been implicated in direct roles in DNA repair, as well as in coordination of the pathways. Here we discuss roles of the checkpoint clamp in DNA damage response (DDR.

  10. Three-dimensional renal CT angiography for guiding segmental renal artery clamping during laparoscopic partial nephrectomy

    International Nuclear Information System (INIS)

    Xu, Yi; Shao, Pengfei; Zhu, Xiaomei; Lv, Qiang; Liu, Wangyan; Xu, Hai; Zhu, Yinsu; Yang, Guangyu; Tang, Lijun; Yin, Changjun

    2013-01-01

    Aim: To evaluate the effectiveness of three-dimensional (3D) renal computed tomography angiography (CTA) in guiding segmental renal artery clamping during laparoscopic partial nephrectomy (LPN). Materials and methods: Forty-three patients with renal tumours undergoing renal CTA before LPN were retrospectively enrolled in this study. 3D arteriogram reconstructed images were created to identify the renal tumour-supplying arteries. The number and location of these targeted vessels were annotated on 3D images preoperatively and compared with the clamped vessels during LPN. The consistency between target vessels annotated at CTA and clamped arteries at LPN was compared both using a patient-based analysis and vessel-based analysis. The χ 2 test was applied to analyse the influence of tumour size, location, and growth pattern on the number of clamped segmental renal branches. Results: On patient-based analysis, the number of targeted vessels was consistent with the clamped vessels during LPN in 33 of 43 patients. On vessel-based analysis, 56 of 65 target vessels annotated at CTA were clamped during LPN. More segmental renal branches (p = 0.04) were clamped in patients with tumours of larger size. Tumour location and growth pattern had no association with the number of clamped segmental branches during LPN. Conclusion: High-quality CTA images and 3D reconstruction images can detect detailed information of tumour-supplying arteries to renal tumours. 3D renal CTA is an effective way to guide segmental renal artery clamping during LPN

  11. 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.

  12. Locoregional Anesthesia for Carotid Endarterectomy: Identification of Patients with Intolerance to Cross-Clamping.

    Science.gov (United States)

    Dellaretti, Marcos; de Vasconcelos, Laura T; Dourado, Jules; de Souza, Renata F; Fontoura, Renato R; de Sousa, Atos A

    2016-03-01

    During carotid endarterectomy (CEA), carotid cross-clamping is performed to allow for artery incision and plaque removal. A small subgroup of patients can tolerate carotid occlusion for only a few seconds, if at all, without presenting neurologic deficit. These patients are described as having ''cross-clamp intolerance.'' The purpose of this study was to demonstrate the safety of locoregional anesthesia in identifying patients with cross-clamp intolerance and factors associated with this condition. From August 2008 to May 2010, 115 consecutive patients were submitted to CEA under locoregional anesthesia at the Santa Casa de Belo Horizonte; the procedure was performed by the main author. Patients who showed intolerance to internal carotid artery (ICA) occlusion for intolerance. Among the 115 participating patients, 9.6% (11 patients) showed intolerance to ICA occlusion and developed deficits in intolerance). The factor that was associated with cross-clamp intolerance was the mean degree of contralateral carotid stenosis, which was 57.5% for those who presented intolerance and 27.8% for those who tolerated ICA occlusion. Locoregional anesthesia is a safe method for identifying patients with cross-clamp intolerance. Patients with cross-clamp intolerance present contralateral stenosis that is greater on average than patients who readily tolerate carotid artery occlusion. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Voltage-sensing phosphatase modulation by a C2 domain.

    Science.gov (United States)

    Castle, Paul M; Zolman, Kevin D; Kohout, Susy C

    2015-01-01

    The voltage-sensing phosphatase (VSP) is the first example of an enzyme controlled by changes in membrane potential. VSP has four distinct regions: the transmembrane voltage-sensing domain (VSD), the inter-domain linker, the cytosolic catalytic domain, and the C2 domain. The VSD transmits the changes in membrane potential through the inter-domain linker activating the catalytic domain which then dephosphorylates phosphatidylinositol phosphate (PIP) lipids. The role of the C2, however, has not been established. In this study, we explore two possible roles for the C2: catalysis and membrane-binding. The Ci-VSP crystal structures show that the C2 residue Y522 lines the active site suggesting a contribution to catalysis. When we mutated Y522 to phenylalanine, we found a shift in the voltage dependence of activity. This suggests hydrogen bonding as a mechanism of action. Going one step further, when we deleted the entire C2 domain, we found voltage-dependent enzyme activity was no longer detectable. This result clearly indicates the entire C2 is necessary for catalysis as well as for modulating activity. As C2s are known membrane-binding domains, we tested whether the VSP C2 interacts with the membrane. We probed a cluster of four positively charged residues lining the top of the C2 and suggested by previous studies to interact with phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] (Kalli et al., 2014). Neutralizing those positive charges significantly shifted the voltage dependence of activity to higher voltages. We tested membrane binding by depleting PI(4,5)P2 from the membrane using the 5HT2C receptor and found that the VSD motions as measured by voltage clamp fluorometry (VCF) were not changed. These results suggest that if the C2 domain interacts with the membrane to influence VSP function it may not occur exclusively through PI(4,5)P2. Together, this data advances our understanding of the VSP C2 by demonstrating a necessary and critical role for the C2 domain in

  14. Characterization of the insulin sensitivity of ghrelin receptor KO mice using glycemic clamps

    Directory of Open Access Journals (Sweden)

    Morgan Kristen

    2011-01-01

    Full Text Available Abstract Background We and others have demonstrated previously that ghrelin receptor (GhrR knock out (KO mice fed a high fat diet (HFD have increased insulin sensitivity and metabolic flexibility relative to WT littermates. A striking feature of the HFD-fed GhrR KO mouse is the dramatic decrease in hepatic steatosis. To characterize further the underlying mechanisms of glucose homeostasis in GhrR KO mice, we conducted both hyperglycemic (HG and hyperinsulinemic-euglycemic (HI-E clamps. Additionally, we investigated tissue glucose uptake and specifically examined liver insulin sensitivity. Results Consistent with glucose tolerance-test data, in HG clamp experiments, GhrR KO mice showed a reduction in glucose-stimulated insulin release relative to WT littermates. Nevertheless, a robust 1st phase insulin secretion was still achieved, indicating that a healthy β-cell response is maintained. Additionally, GhrR KO mice demonstrated both a significantly increased glucose infusion rate and significantly reduced insulin requirement for maintenance of the HG clamp, consistent with their relative insulin sensitivity. In HI-E clamps, both LFD-fed and HFD-fed GhrR KO mice showed higher peripheral insulin sensitivity relative to WT littermates as indicated by a significant increase in insulin-stimulated glucose disposal (Rd, and decreased hepatic glucose production (HGP. HFD-fed GhrR KO mice showed a marked increase in peripheral tissue glucose uptake in a variety of tissues, including skeletal muscle, brown adipose tissue and white adipose tissue. GhrR KO mice fed a HFD also showed a modest, but significant decrease in conversion of pyruvate to glucose, as would be anticipated if these mice displayed increased liver insulin sensitivity. Additionally, the levels of UCP2 and UCP1 were reduced in the liver and BAT, respectively, in GhrR KO mice relative to WT mice. Conclusions These results indicate that improved glucose homeostasis of GhrR KO mice is

  15. On the Nonlinear Dynamics of a Doubly Clamped Microbeam near Primary Resonance

    KAUST Repository

    Jaber, Nizar; Masri, Karim M.; Younis, Mohammad I.

    2017-01-01

    This work aims to investigate theoretically and experimentally various nonlinear dynamic behaviors of a doubly clamped microbeam near its primary resonance. Mainly, we investigate the transition behavior from hardening, mixed, and then softening behavior. We show in a single frequency-response curve, under a constant voltage load, the transition from hardening to softening behavior demonstrating the dominance of the quadratic electrostatic nonlinearity over the cubic geometric nonlinearity of the beam as the motion amplitudes becomes large, which may lead eventually to dynamic pull-in. The microbeam is fabricated using polyimide as a structural layer coated with nickel from top and chromium and gold layers from the bottom. Frequency sweep tests are conducted for different values of DC bias revealing hardening, mixed, and softening behavior of the microbeam. A multi-mode Galerkin model combined with a shooting technique are implemented to generate the frequency response curves and to analyze the stability of the periodic motions using the Floquet theory. The simulated curves show good agreement with the experimental data.

  16. On the Nonlinear Dynamics of a Doubly Clamped Microbeam near Primary Resonance

    KAUST Repository

    Jaber, Nizar

    2017-04-07

    This work aims to investigate theoretically and experimentally various nonlinear dynamic behaviors of a doubly clamped microbeam near its primary resonance. Mainly, we investigate the transition behavior from hardening, mixed, and then softening behavior. We show in a single frequency-response curve, under a constant voltage load, the transition from hardening to softening behavior demonstrating the dominance of the quadratic electrostatic nonlinearity over the cubic geometric nonlinearity of the beam as the motion amplitudes becomes large, which may lead eventually to dynamic pull-in. The microbeam is fabricated using polyimide as a structural layer coated with nickel from top and chromium and gold layers from the bottom. Frequency sweep tests are conducted for different values of DC bias revealing hardening, mixed, and softening behavior of the microbeam. A multi-mode Galerkin model combined with a shooting technique are implemented to generate the frequency response curves and to analyze the stability of the periodic motions using the Floquet theory. The simulated curves show good agreement with the experimental data.

  17. Precision monitoring and calibration of the high-voltage for the KATRIN experiment; Praezisionsueberwachung und Kalibration der Hochspannung fuer das KATRIN-Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Thuemmler, T.

    2007-11-12

    The goal of the KATRIN(KArlsruhe TRIritium Neutrino) Experiment is to directly determine the neutrino rest mass from the kinematics of the tritium-{beta}-decay. KATRIN uses the high resolution and luminosity of a spectrometer following the MAC-E filter principle. Based on the experience of the successful predecessor experiments in Mainz and Troisk and the improved experimental technology, KATRIN aims to reach a sensitivity on the neutrino mass of 0.2 eV/c{sup 2} (90% C.L.). One of the few systematic uncertainties that have to be reduced to meet this goal is the uncertainty of measuring and monitoring the potential of the electrostatic filter of the spectrometer. In tritium measurement mode voltages of about U{sub 0} =-18.6 kV have to be permanently monitored with a maximum uncertainty of 3.3 ppm ({approx} 61mV at U{sub 0}), in order not to add more than {delta}m{sup 2}{sub {nu}{sub ec}}{sup 4} {<=} 0.0075 eV{sup 2} to the total systematic uncertainty. The goal of this work is to build a new precision high voltage divider in cooperation with PTB Braunschweig that reaches an uncertainty of about 1 ppm at voltages up to 35 kV. The divider is based on a new type of precision resistors, which have been screened with respect to their warm up drift and their temperature coefficient at the ppm level. By combining 100 of the best matching samples, the mutual warm up effect could be reduced to a computed value of <0.02 ppm. The precision resistors are mounted in a shielded and temperature stabilized vessel under N{sub 2} gas. The properties of both installed low voltage outputs with the ratios 1972:1 and 3944:1 have been repeatedly calibrated with about one year time difference at the DC high voltage laboratory (division 2.31) of PTB. The performance of the new divider in real measurements has been tested with the prototype of the new condensed {sup 83m}Kr calibration source (CKrS) [Ost08] at the Mainz spectrometer. Detailed stability investigations of the energy of the {sup

  18. Dynamic assembly of Hda and the sliding clamp in the regulation of replication licensing.

    Science.gov (United States)

    Kim, Jin S; Nanfara, Michael T; Chodavarapu, Sundari; Jin, Kyeong S; Babu, Vignesh M P; Ghazy, Mohamed A; Chung, Scisung; Kaguni, Jon M; Sutton, Mark D; Cho, Yunje

    2017-04-20

    Regulatory inactivation of DnaA (RIDA) is one of the major regulatory mechanisms of prokaryotic replication licensing. In RIDA, the Hda-sliding clamp complex loaded onto DNA directly interacts with adenosine triphosphate (ATP)-bound DnaA and stimulates the hydrolysis of ATP to inactivate DnaA. A prediction is that the activity of Hda is tightly controlled to ensure that replication initiation occurs only once per cell cycle. Here, we determined the crystal structure of the Hda-β clamp complex. This complex contains two pairs of Hda dimers sandwiched between two β clamp rings to form an octamer that is stabilized by three discrete interfaces. Two separate surfaces of Hda make contact with the β clamp, which is essential for Hda function in RIDA. The third interface between Hda monomers occludes the active site arginine finger, blocking its access to DnaA. Taken together, our structural and mutational analyses of the Hda-β clamp complex indicate that the interaction of the β clamp with Hda controls the ability of Hda to interact with DnaA. In the octameric Hda-β clamp complex, the inability of Hda to interact with DnaA is a novel mechanism that may regulate Hda function. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  19. 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....

  20. 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....

  1. trans-Caryophyllene, a Natural Sesquiterpene, Causes Tracheal Smooth Muscle Relaxation through Blockade of Voltage-Dependent Ca2+ Channels

    Directory of Open Access Journals (Sweden)

    Jader Santos Cruz

    2012-10-01

    Full Text Available trans-Caryophyllene is a major component in the essential oils of various species of medicinal plants used in popular medicine in Brazil. It belongs to the chemical class of the sesquiterpenes and has been the subject of a number of studies. Here, we evaluated the effects of this compound in airway smooth muscle. The biological activities of trans-caryophyllene were examined in isolated bath organs to investigate the effect in basal tonus. Electromechanical and pharmacomechanical couplings were evaluated through the responses to K+ depolarization and exposure to acetylcholine (ACh, respectively. Isolated cells of rat tracheal smooth muscle were used to investigate trans-caryophyllene effects on voltage-dependent Ca2+ channels by using the whole-cell voltage-clamp configuration of the patch-clamp technique. trans-Caryophyllene showed more efficiency in the blockade of electromechanical excitation-contraction coupling while it has only minor inhibitory effect on pharmacomechanical coupling. Epithelium removal does not modify tracheal smooth muscle response elicited by trans-caryophyllene in the pharmacomechanical coupling. Under Ca2+-free conditions, pre-exposure to trans-caryophyllene did not reduce the contraction induced by ACh in isolated rat tracheal smooth muscle, regardless of the presence of intact epithelium. In the whole-cell configuration, trans-caryophyllene (3 mM, inhibited the inward Ba2+ current (IBa to approximately 50% of control levels. Altogether, our results demonstrate that trans-caryophyllene has anti-spasmodic activity on rat tracheal smooth muscle which could be explained, at least in part, by the voltage-dependent Ca2+ channels blockade.

  2. Regulation of Na+ channel inactivation by the DIII and DIV voltage-sensing domains.

    Science.gov (United States)

    Hsu, Eric J; Zhu, Wandi; Schubert, Angela R; Voelker, Taylor; Varga, Zoltan; Silva, Jonathan R

    2017-03-06

    Functional eukaryotic voltage-gated Na + (Na V ) channels comprise four domains (DI-DIV), each containing six membrane-spanning segments (S1-S6). Voltage sensing is accomplished by the first four membrane-spanning segments (S1-S4), which together form a voltage-sensing domain (VSD). A critical Na V channel gating process, inactivation, has previously been linked to activation of the VSDs in DIII and DIV. Here, we probe this interaction by using voltage-clamp fluorometry to observe VSD kinetics in the presence of mutations at locations that have been shown to impair Na V channel inactivation. These locations include the DIII-DIV linker, the DIII S4-S5 linker, and the DIV S4-S5 linker. Our results show that, within the 10-ms timeframe of fast inactivation, the DIV-VSD is the primary regulator of inactivation. However, after longer 100-ms pulses, the DIII-DIV linker slows DIII-VSD deactivation, and the rate of DIII deactivation correlates strongly with the rate of recovery from inactivation. Our results imply that, over the course of an action potential, DIV-VSDs regulate the onset of fast inactivation while DIII-VSDs determine its recovery. © 2017 Hsu et al.

  3. Independent control strategy of two DC-link voltages for separate MPPTs in transformerless photovoltaic systems using neutral-point-clamped inverters

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede; Lee, Kyo-Beum

    2014-01-01

    To improve the efficiency of the photovoltaic (PV) system, the centralized topology using three-level inverters are widely used. In this system, PV modules are separately connected to the split DC-links. This causes a decrease of maximum power point tracking (MPPT) efficiency under the partial...... shading condition. This paper proposes an independent control of two DC-link voltages for separate MPPT of each PV module in three-level inverters. The proposed method is simply implemented by adding or subtracting the time-offset to the three-phase turn-on times and modifying the reference voltages...

  4. Diagnostic method for measuring plasma-induced voltages on the PBX-M [Princeton Beta Experiment-Modified] stabilizing shell

    International Nuclear Information System (INIS)

    Kugel, H.W.; Okabayashi, M.; Schweitzer, S.

    1990-07-01

    The Princeton Beta Experiment-Modified (PBX-M) has a close-fitting conducting, passive plate, stabilizing shell which nearly surrounds highly indented, bean-shaped plasmas. The proximity of this electrically isolated shell to a large fraction of the plasma surface allows measurements similar to previous work on other tokamaks using floating probes and limiters. Measurements were performed to characterize the plasma-induced voltages on the PBX-M passive plate stabilizing shell during high-β plasmas. Voltage differences were measured between the respective passive plate toroidal and poloidal gaps, the respective passive plates and the vessel, and an outer poloidal graphite limiter and its passive plate. The calibration and qualification testing procedures are discussed. The initial measurements found that the largest voltages were observed at plasma start-up and at the plasma current disruption and exhibited characteristics depending on operating conditions. The highest voltages observed have been at disruption and were less than 2 kV. 9 refs., 5 figs

  5. Local anesthetics disrupt energetic coupling between the voltage-sensing segments of a sodium channel.

    Science.gov (United States)

    Muroi, Yukiko; Chanda, Baron

    2009-01-01

    Local anesthetics block sodium channels in a state-dependent fashion, binding with higher affinity to open and/or inactivated states. Gating current measurements show that local anesthetics immobilize a fraction of the gating charge, suggesting that the movement of voltage sensors is modified when a local anesthetic binds to the pore of the sodium channel. Here, using voltage clamp fluorescence measurements, we provide a quantitative description of the effect of local anesthetics on the steady-state behavior of the voltage-sensing segments of a sodium channel. Lidocaine and QX-314 shifted the midpoints of the fluorescence-voltage (F-V) curves of S4 domain III in the hyperpolarizing direction by 57 and 65 mV, respectively. A single mutation in the S6 of domain IV (F1579A), a site critical for local anesthetic block, abolished the effect of QX-314 on the voltage sensor of domain III. Both local anesthetics modestly shifted the F-V relationships of S4 domain IV toward hyperpolarized potentials. In contrast, the F-V curve of the S4 domain I was shifted by 11 mV in the depolarizing direction upon QX-314 binding. These antagonistic effects of the local anesthetic indicate that the drug modifies the coupling between the voltage-sensing domains of the sodium channel. Our findings suggest a novel role of local anesthetics in modulating the gating apparatus of the sodium channel.

  6. Application and analysis of retroperitoneal laparoscopic partial nephrectomy with sequential segmental renal artery clamping for patients with multiple renal tumor: initial experience.

    Science.gov (United States)

    Zhu, Jundong; Jiang, Fan; Li, Pu; Shao, Pengfei; Liang, Chao; Xu, Aiming; Miao, Chenkui; Qin, Chao; Wang, Zengjun; Yin, Changjun

    2017-09-11

    To explore the feasibility and safety of retroperitoneal laparoscopic partial nephrectomy with sequential segmental renal artery clamping for the patients with multiple renal tumor of who have solitary kidney or contralateral kidney insufficiency. Nine patients who have undergone retroperitoneal laparoscopic partial nephrectomy with sequential segmental renal artery clamping between October 2010 and January 2017 were retrospectively analyzed. Clinical materials and parameters during and after the operation were summarized. Nineteen tumors were resected in nine patients and the operations were all successful. The operation time ranged from 100 to 180 min (125 min); clamping time of segmental renal artery was 10 ~ 30 min (23 min); the amount of blood loss during the operation was 120 ~ 330 ml (190 ml); hospital stay after the operation is 3 ~ 6d (5d). There was no complication during the perioperative period, and the pathology diagnosis after the surgery showed that there were 13 renal clear cell carcinomas, two papillary carcinoma and four perivascular epithelioid cell tumors with negative margins from the 19 tumors. All patients were followed up for 3 ~ 60 months, and no local recurrence or metastasis was detected. At 3-month post-operation follow-up, the mean serum creatinine was 148.6 ± 28.1 μmol/L (p = 0.107), an increase of 3.0 μmol/L from preoperative baseline. For the patients with multiple renal tumors and solitary kidney or contralateral kidney insufficiency, retroperitoneal laparoscopic partial nephrectomy with sequential segmental renal artery clamping was feasible and safe, which minimized the warm ischemia injury to the kidney and preserved the renal function effectively.

  7. Modelling the clamping force distribution among chips in press-pack IGBTs using the finite element method

    DEFF Research Database (Denmark)

    Hasmasan, Adrian Augustin; Busca, Christian; Teodorescu, Remus

    2012-01-01

    In this paper, a FEM (finite element method) based mechanical model for PP (press-pack) IGBTs (insulated gate bipolar transistors) is presented, which can be used to calculate the clamping force distribution among chips under various clamping conditions. The clamping force is an important parameter...... for the chip, because it influences contact electrical resistance, contact thermal resistance and power cycling capability. Ideally, the clamping force should be equally distributed among chips, in order to maximize the reliability of the PP IGBT. The model is built around a hypothetical PP IGBT with 9 chips......, and it has numerous simplifications in order to reduce the simulation time as much as possible. The developed model is used to analyze the clamping force distribution among chips, in various study cases, where uniform and non-uniform clamping pressures are applied on the studied PP IGBT....

  8. An isolated Hda-clamp complex is functional in the regulatory inactivation of DnaA and DNA replication.

    Science.gov (United States)

    Kawakami, Hironori; Su'etsugu, Masayuki; Katayama, Tsutomu

    2006-10-01

    In Escherichia coli, a complex consisting of Hda and the DNA-loaded clamp-subunit of the DNA polymerase III holoenzyme promotes hydrolysis of DnaA-ATP. The resultant ADP-DnaA is inactive for initiation of chromosomal DNA replication, thereby repressing excessive initiations. As the cellular content of the clamp is 10-100 times higher than that of Hda, most Hda molecules might be complexed with the clamp in vivo. Although Hda predominantly forms irregular aggregates when overexpressed, in the present study we found that co-overexpression of the clamp with Hda enhances Hda solubility dramatically and we efficiently isolated the Hda-clamp complex. A single molecule of the complex appears to consist of two Hda molecules and a single clamp. The complex is competent in DnaA-ATP hydrolysis and DNA replication in the presence of DNA and the clamp deficient subassembly of the DNA polymerase III holoenzyme (pol III*). These findings indicate that the clamp contained in the complex is loaded onto DNA through an interaction with the pol III* and that the Hda activity is preserved in these processes. The complex consisting of Hda and the DNA-unloaded clamp may play a specific role in a process proceeding to the DnaA-ATP hydrolysis in vivo.

  9. Patch Clamp: A Powerful Technique for Studying the Mechanism of Acupuncture

    Directory of Open Access Journals (Sweden)

    D. Zhang

    2012-01-01

    Full Text Available Cellular and molecular events can be investigated using electrophysiological techniques. In particular, the patch-clamp method provides detailed information. In addition, the patch-clamp technique has become a powerful method for investigating the mechanisms underlying the effects of acupuncture. In this paper, recent researches on how acupuncture might modulate electrophysiological responses in the central nervous system (CNS and affect peripheral structures are reviewed.

  10. SGK3 Sensitivity of Voltage Gated K+ Channel Kv1.5 (KCNA5

    Directory of Open Access Journals (Sweden)

    Musaab Ahmed

    2016-01-01

    Full Text Available Background: The serum & glucocorticoid inducible kinase isoform SGK3 is a powerful regulator of several transporters, ion channels and the Na+/K+ ATPase. Targets of SGK3 include the ubiquitin ligase Nedd4-2, which is in turn a known regulator of the voltage gated K+ channel Kv1.5 (KCNA5. The present study thus explored whether SGK3 modifies the activity of the voltage gated K+ channel KCNA5, which participates in the regulation of diverse functions including atrial cardiac action potential, activity of vascular smooth muscle cells, insulin release and tumour cell proliferation. Methods: cRNA encoding KCNA5 was injected into Xenopus oocytes with and without additional injection of cRNA encoding wild-type SGK3, constitutively active S419DSGK3, inactive K191NSGK3 and/or wild type Nedd4-2. Voltage gated K+ channel activity was quantified utilizing dual electrode voltage clamp. Results: Voltage gated current in KCNA5 expressing Xenopus oocytes was significantly enhanced by wild-type SGK3 and S419DSGK3, but not by K191NSGK3. SGK3 was effective in the presence of ouabain (1 mM and thus did not require Na+/K+ ATPase activity. Coexpression of Nedd4-2 decreased the voltage gated current in KCNA5 expressing Xenopus oocytes, an effect largely reversed by additional coexpression of SGK3. Conclusion: SGK3 is a positive regulator of KCNA5, which is at least partially effective by abrogating the effect of Nedd4-2.

  11. Prediction of clamp-derived insulin sensitivity from the oral glucose insulin sensitivity index

    DEFF Research Database (Denmark)

    Tura, Andrea; Chemello, Gaetano; Szendroedi, Julia

    2018-01-01

    that underwent both a clamp and an OGTT or meal test, thereby allowing calculation of both the M value and OGIS. The population was divided into a training and a validation cohort (n = 359 and n = 154, respectively). After a stepwise selection approach, the best model for M value prediction was applied......AIMS/HYPOTHESIS: The euglycaemic-hyperinsulinaemic clamp is the gold-standard method for measuring insulin sensitivity, but is less suitable for large clinical trials. Thus, several indices have been developed for evaluating insulin sensitivity from the oral glucose tolerance test (OGTT). However......, most of them yield values different from those obtained by the clamp method. The aim of this study was to develop a new index to predict clamp-derived insulin sensitivity (M value) from the OGTT-derived oral glucose insulin sensitivity index (OGIS). METHODS: We analysed datasets of people...

  12. Investigation on the Behavior of the Jointing Clamps to the Simulated Environmental - LOCA

    International Nuclear Information System (INIS)

    Ivan, P.; Segarceanu, D.; Geambasu, C.

    2002-01-01

    The paper presents the main aspect concerning the electric parameter variation of jointing clamps operating under specific environmental conditions determinate by pressure, temperature and humidity. The testing of jointing clamps capability to meet and exceed the required performances all along its operating life implies the performing of LOCA simulation conditions while the jointing clamps is bright in a relatively short time under conditions equivalent to those at the end of its service life. The paper describes ageing and measurement techniques and the analyses of electric parameter behaviour in these environmental simulated conditions. (author)

  13. Identification of an HV 1 voltage-gated proton channel in insects.

    Science.gov (United States)

    Chaves, Gustavo; Derst, Christian; Franzen, Arne; Mashimo, Yuta; Machida, Ryuichiro; Musset, Boris

    2016-04-01

    The voltage-gated proton channel 1 (HV 1) is an important component of the cellular proton extrusion machinery and is essential for charge compensation during the respiratory burst of phagocytes. HV 1 has been identified in a wide range of eukaryotes throughout the animal kingdom, with the exception of insects. Therefore, it has been proposed that insects do not possess an HV 1 channel. In the present study, we report the existence of an HV 1-type proton channel in insects. We searched insect transcriptome shotgun assembly (TSA) sequence databases and found putative HV 1 orthologues in various polyneopteran insects. To confirm that these putative HV 1 orthologues were functional channels, we studied the HV 1 channel of Nicoletia phytophila (NpHV 1), an insect of the Zygentoma order, in more detail. NpHV 1 comprises 239 amino acids and is 33% identical to the human voltage-gated proton channel 1. Patch clamp measurements in a heterologous expression system showed proton selectivity, as well as pH- and voltage-dependent gating. Interestingly, NpHV 1 shows slightly enhanced pH-dependent gating compared to the human channel. Mutations in the first transmembrane segment at position 66 (Asp66), the presumed selectivity filter, lead to a loss of proton-selective conduction, confirming the importance of this aspartate residue in voltage-gated proton channels. Nucleotide sequence data have been deposited in the GenBank database under accession number KT780722. © 2016 Federation of European Biochemical Societies.

  14. 2D and 3D assessment of sustentaculum tali screw fixation with or without Screw Targeting Clamp.

    Science.gov (United States)

    De Boer, A Siebe; Van Lieshout, Esther M M; Vellekoop, Leonie; Knops, Simon P; Kleinrensink, Gert-Jan; Verhofstad, Michael H J

    2017-12-01

    Precise placement of sustentaculum tali screw(s) is essential for restoring anatomy and biomechanical stability of the calcaneus. This can be challenging due to the small target area and presence of neurovascular structures on the medial side. The aim was to evaluate the precision of positioning of the subchondral posterior facet screw and processus anterior calcanei screw with or without a Screw Targeting Clamp. The secondary aim was to evaluate the added value of peroperative 3D imaging over 2D radiographs alone. Twenty Anubifix™ embalmed, human anatomic lower limb specimens were used. A subchondral posterior facet screw and a processus anterior calcanei screw were placed using an extended lateral approach. A senior orthopedic trauma surgeon experienced in calcaneal fracture surgery and a senior resident with limited experience in calcaneal surgery performed screw fixation in five specimens with and in five specimens without the clamp. 2D lateral and axial radiographs and a 3D recording were obtained postoperatively. Anatomical dissection was performed postoperatively as a diagnostic golden standard in order to obtain the factual screw positions. Blinded assessment of quality of fixation was performed by two surgeons. In 2D, eight screws were considered malpositioned when placed with the targeting device versus nine placed freehand. In 3D recordings, two additional screws were malpositioned in each group as compared to the golden standard. As opposed to the senior surgeon, the senior resident seemed to get the best results using the Screw Targeting Clamp (number of malpositioned screws using freehand was eight, and using the targeting clamp five). In nine out of 20 specimens 3D images provided additional information concerning target area and intra-articular placement. Based on the 3D assessment, five additional screws would have required repositioning. Except for one, all screw positions were rated equally after dissection when compared with 3D examinations

  15. Clamp and Gas Nozzle for TIG Welding

    Science.gov (United States)

    Gue, G. B.; Goller, H. L.

    1982-01-01

    Tool that combines clamp with gas nozzle is aid to tungsten/inert-gas (TIG) welding in hard-to-reach spots. Tool holds work to be welded while directing a stream of argon gas at weld joint, providing an oxygen-free environment for tungsten-arc welding.

  16. Timing of umbilical cord-clamping and infant anaemia: the role of maternal anaemia.

    Science.gov (United States)

    Blouin, Brittany; Penny, Mary E; Maheu-Giroux, Mathieu; Casapía, Martín; Aguilar, Eder; Silva, Hermánn; Creed-Kanashiro, Hilary M; Joseph, Serene A; Gagnon, Anita; Rahme, Elham; Gyorkos, Theresa W

    2013-05-01

    Evidence from randomized controlled trials has shown that delayed cord-clamping is beneficial to infant iron status. The role of maternal anaemia in this relationship, however, has not been established. To determine the effect of maternal anaemia at delivery on the association between timing of umbilical cord-clamping and infant anaemia at 4 and 8 months of age. A cohort of pregnant women admitted to the labour room of Hospital Iquitos (Iquitos, Peru) and their newborns were recruited into the study during two time periods (18 May to 3 June and 6-20 July 2009). Between the two recruitment periods, the hospital's policy changed from early to delayed umbilical cord-clamping. Maternal haemoglobin levels were measured before delivery, and the time between delivery and cord-clamping was recorded at delivery for the entire cohort. Mother-infant pairs were followed-up at 4 (n = 207) and 8 months (n = 184) post partum. Infant haemoglobin levels were measured at follow-up visits. Data were analysed using logistic regression models. The prevalence of maternal anaemia (Hb anaemia was modified by the mother's anaemia status. Significant benefits of delayed cord-clamping in preventing anaemia were found in infants born to anaemic mothers at both 4 months (aOR = 0.59, 95% CI 0.36-0.99) and 8 months (aOR = 0.38, 95% CI 0.19-0.76) of age. The study contributes additional evidence in support of delayed cord-clamping. This intervention is likely to have most public health impact in areas with a high prevalence of anaemia during pregnancy.

  17. Actuator Location and Voltages Optimization for Shape Control of Smart Beams Using Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Georgios E. Stavroulakis

    2013-10-01

    Full Text Available This paper presents a numerical study on optimal voltages and optimal placement of piezoelectric actuators for shape control of beam structures. A finite element model, based on Timoshenko beam theory, is developed to characterize the behavior of the structure and the actuators. This model accounted for the electromechanical coupling in the entire beam structure, due to the fact that the piezoelectric layers are treated as constituent parts of the entire structural system. A hybrid scheme is presented based on great deluge and genetic algorithm. The hybrid algorithm is implemented to calculate the optimal locations and optimal values of voltages, applied to the piezoelectric actuators glued in the structure, which minimize the error between the achieved and the desired shape. Results from numerical simulations demonstrate the capabilities and efficiency of the developed optimization algorithm in both clamped−free and clamped−clamped beam problems are presented.

  18. In-situ experimental characterization of the clamping pressure effects on low temperature polymer electrolyte membrane electrolysis

    DEFF Research Database (Denmark)

    Al Shakhshir, Saher; Cui, Xiaoti; Frensch, Steffen Henrik

    2017-01-01

    as a gas with the circulating water. The effects of clamping pressure (Pc) on the LT-PEME cell performance, polarization resistances, and hydrogen and water crossover through the membrane, and hydrogen and oxygen production rate are studied. A 50 cm2 active area LT-PEME cell designed and manufactured......-PEME splits water into hydrogen and oxygen when the voltage is applied between anode and cathode. Electrical current forces the positively charged ions to migrate to negatively charged cathode through PEM, where hydrogen is produced. Meanwhile, oxygen is produced at the anode side electrode and escapes...... in house is utilized in this work. Higher Pc has shown higher cell performance this refers to lower ohmic and activation resistances. Water crossover from anode to cathode is slightly decreased at higher Pc resulting in a slight decrease in hydrogen crossover from cathode to anode. Also, the percentage...

  19. Enhancing endogenous stem cells in the newbornvia delayed umbilical cord clamping

    Institute of Scientific and Technical Information of China (English)

    Christopher Lawton; Sandra Acosta; Nate Watson; Chiara Gonzales-Portillo; hTeo Diamandis; Naoki Tajiri; Yuji Kaneko; Paul R. Sanberg; Cesar V. Borlongan

    2015-01-01

    There is currently no consensus among clinicians and scientists over the appropriate or optimal timing for umbilical cord clamping. However, many clinical studies have suggested that delayed cord clamping is associated with various neonatal beneifts including increased blood volume, reduced need for blood transfusion, increased cerebral oxygenation in pre-term infants, and decreased frequency of iron deifciency anemia in term infants. Human umbilical cord blood con-tains signiifcant amounts of stem and progenitor cells and is currently used in the treatment of several life-threatening diseases. We propose that delayed cord clamping be encouraged as it en-hances blood lfow from the placenta to the neonate, which is accompanied by an increase supply of valuable stem and progenitor cells, as well as may improve blood oxygenation and increase blood volume, altogether reducing the infant’s susceptibility to both neonatal and age-related diseases.

  20. Clampe de Ganz no tratamento de urgência em lesões do anel pélvico Ganz clamps to treat emergencies in pelvic ring lesions

    Directory of Open Access Journals (Sweden)

    Gilberto José Cação Pereira

    2008-07-01

    Full Text Available OBJETIVO: Avaliar a eficiência do clampe de Ganz na estabilização e redução dos deslocamentos da pelve, quando utilizado no tratamento de urgência, além de aquilatar eventuais dificuldades e facilidades do método. MÉTODOS: O clampe de Ganz foi utilizado no tratamento de urgência em 31 pacientes com graves lesões do anel pélvico (Tile C associadas a importante instabilidade hemodinâmica. RESULTADO: Entre os pacientes, 27 (87,1% apresentaram evolução favorável, com estabilização, redução dos deslocamentos e compressão da região posterior do anel, além de estabilização hemodinâmica, e quatro (12,9% evoluíram para óbito. CONCLUSÃO: O clampe de Ganz mostrou-se eficiente ferramenta no tratamento de urgência das lesões do anel pélvico, por ser de concepção simples, de rápida colocação, não impedir ou dificultar procedimentos no abdome e, principalmente, por permitir a estabilização da pelve, redução dos deslocamentos e compressão na região posterior do anel, local onde ocorrem os maiores sangramentos, reduzindo-os ou eliminando-os.OBJECTIVE: To evaluate the effectiveness of Ganz clamp to stabilize and reduce pelvic dislocations in emergency situations, and to assess possible difficult and easy aspects of the method. METHOD: Ganz clamp was used in the emergency treatment of 31 patients with severe lesions of the pelvic ring (Tile C associated to major hemodynamic instability. RESULTS: Among the patients, 27 (87.1% presented a favorable evolution, with stabilization, reduction of dislocations, and compression of the posterior portion of the ring, and also hemodynamic stabilization, and 4 (12.9% died. CONCLUSION: The Ganz clamp was found to be an effective tool in the emergency treatment of pelvic ring lesions because it has an uncomplicated conception, allowing for a fast placement, because it does not prevent nor make it difficult for abdominal procedures, and most of all because it allows for the

  1. Evaluation of Introduction of a Delayed Cord Clamping Protocol for Premature Neonates in a High-Volume Maternity Center.

    Science.gov (United States)

    Liu, Lilly Y; Feinglass, Joe M; Khan, Janine Y; Gerber, Susan E; Grobman, William A; Yee, Lynn M

    2017-05-01

    To evaluate adherence to a delayed cord clamping protocol for preterm births in the first 2 years after its introduction, perform a quality improvement assessment, and determine neonatal outcomes associated with protocol implementation and adherence. This is a retrospective cohort study of women delivering singleton neonates at 23-32 weeks of gestation in the 2 years before (preprotocol) and 2 years after (postprotocol) introduction of a 30-second delayed cord clamping protocol at a large-volume academic center. This policy was communicated to obstetric and pediatric health care providers and nurses and reinforced with intermittent educational reviews. Barriers to receiving delayed cord clamping were assessed using χ tests and multivariable logistic regression. Neonatal outcomes then were compared between all neonates in the preprotocol period and all neonates in the postprotocol period and between all neonates in the preprotocol period and neonates receiving delayed cord clamping in the postprotocol period using multivariable linear and logistic regression analyses. Of the 427 eligible neonates, 187 were born postprotocol. Of these, 53.5% (n=100) neonates received delayed cord clamping according to the protocol. The rate of delayed cord clamping preprotocol was 0%. Protocol uptake and frequency of delayed cord clamping increased over the 2 years after its introduction. In the postprotocol period, cesarean delivery was the only factor independently associated with failing to receive delayed cord clamping (adjusted odds ratio [OR] 0.49, 95% confidence interval [CI] 0.25-0.96). In comparison with the preprotocol period, those who received delayed cord clamping in the postprotocol period had significantly higher birth hematocrit (β=2.46, P=.007) and fewer blood transfusions in the first week of life (adjusted OR 0.49, 95% CI 0.25-0.96). After introduction of an institutional delayed cord clamping protocol followed by continued health care provider education and

  2. Voltage-sensing phosphatase modulation by a C2 domain

    Directory of Open Access Journals (Sweden)

    Paul M. Castle

    2015-04-01

    Full Text Available The voltage-sensing phosphatase (VSP is the first example of an enzyme controlled by changes in membrane potential. VSP has four distinct regions: the transmembrane voltage-sensing domain (VSD, the inter-domain linker, the cytosolic catalytic domain and the C2 domain. The VSD transmits the changes in membrane potential through the inter-domain linker activating the catalytic domain which then dephosphorylates phosphatidylinositol phosphate lipids. The role of the C2, however, has not been established. In this study, we explore two possible roles for the C2: catalysis and membrane-binding. The Ci-VSP crystal structures show that the C2 residue Y522 lines the active site suggesting a contribution to catalysis. When we mutated Y522 to phenylalanine, we found a shift in the voltage dependence of activity. This suggests hydrogen bonding as a mechanism of action. Going one step further, when we deleted the entire C2 domain, we found voltage-dependent enzyme activity was no longer detectable. This result clearly indicates the entire C2 is necessary for catalysis as well as for modulating activity. As C2s are known membrane-binding domains, we tested whether the VSP C2 interacts with the membrane. We probed a cluster of four positively charged residues lining the top of the C2 and suggested by previous studies to interact with phosphatidylinositol 4,5-bisphosphate (PI(4,5P2 (Kalli et al., 2014. Neutralizing those positive charges significantly shifted the voltage dependence of activity to higher voltages. We tested membrane binding by depleting PI(4,5P2 from the membrane using the 5HT2C receptor and found that the VSD motions as measured by voltage clamp fluorometry were not changed. These results suggest that if the C2 domain interacts with the membrane to influence VSP function it may not occur exclusively through PI(4,5P2. Together, this data advances our understanding of the VSP C2 by demonstrating a necessary and critical role for the C2 domain in

  3. Modulation of voltage-gated channel currents by harmaline and harmane.

    Science.gov (United States)

    Splettstoesser, Frank; Bonnet, Udo; Wiemann, Martin; Bingmann, Dieter; Büsselberg, Dietrich

    2005-01-01

    Harmala alkaloids are endogenous substances, which are involved in neurodegenerative disorders such as M. Parkinson, but some of them also have neuroprotective effects in the nervous system. While several sites of action at the cellular level (e.g. benzodiazepine receptors, 5-HT and GABA(A) receptors) have been identified, there is no report on how harmala alkaloids interact with voltage-gated membrane channels. The aim of this study was to investigate the effects of harmaline and harmane on voltage-activated calcium- (I(Ca(V))), sodium- (I(Na(V))) and potassium (I(K(V)))-channel currents, using the whole-cell patch-clamp method with cultured dorsal root ganglion neurones of 3-week-old rats. Currents were elicited by voltage steps from the holding potential to different command potentials. Harmaline and harmane reduced I(Ca(V)), I(Na(V)) and I(K(V)) concentration-dependent (10-500 microM) over the voltage range tested. I(Ca(V)) was reduced with an IC(50) of 100.6 microM for harmaline and by a significantly lower concentration of 75.8 microM (P<0.001, t-test) for harmane. The Hill coefficient was close to 1. Threshold concentration was around 10 microM for both substances. The steady state of inhibition of I(Ca(V)) by harmaline or harmane was reached within several minutes. The action was not use-dependent and at least partly reversible. It was mainly due to a reduction in the sustained calcium channel current (I(Ca(L+N))), while the transient voltage-gated calcium channel current (I(Ca(T))) was only partially affected. We conclude that harmaline and harmane are modulators of I(Ca(V)) in vitro. This might be related to their neuroprotective effects.

  4. Higher order modes excitation of electrostatically actuated clamped–clamped microbeams: experimental and analytical investigation

    KAUST Repository

    Jaber, Nizar; Ramini, Abdallah; Carreno, Armando Arpys Arevalo; Younis, Mohammad I.

    2016-01-01

    © 2016 IOP Publishing Ltd. In this study, we demonstrate analytically and experimentally the excitations of the higher order modes of vibrations in electrostatically actuated clamped-clamped microbeam resonators. The concept is based on using

  5. Non-linear Membrane Properties in Entorhinal Cortical Stellate Cells Reduce Modulation of Input-Output Responses by Voltage Fluctuations

    Science.gov (United States)

    Fernandez, Fernando R.; Malerba, Paola; White, John A.

    2015-01-01

    The presence of voltage fluctuations arising from synaptic activity is a critical component in models of gain control, neuronal output gating, and spike rate coding. The degree to which individual neuronal input-output functions are modulated by voltage fluctuations, however, is not well established across different cortical areas. Additionally, the extent and mechanisms of input-output modulation through fluctuations have been explored largely in simplified models of spike generation, and with limited consideration for the role of non-linear and voltage-dependent membrane properties. To address these issues, we studied fluctuation-based modulation of input-output responses in medial entorhinal cortical (MEC) stellate cells of rats, which express strong sub-threshold non-linear membrane properties. Using in vitro recordings, dynamic clamp and modeling, we show that the modulation of input-output responses by random voltage fluctuations in stellate cells is significantly limited. In stellate cells, a voltage-dependent increase in membrane resistance at sub-threshold voltages mediated by Na+ conductance activation limits the ability of fluctuations to elicit spikes. Similarly, in exponential leaky integrate-and-fire models using a shallow voltage-dependence for the exponential term that matches stellate cell membrane properties, a low degree of fluctuation-based modulation of input-output responses can be attained. These results demonstrate that fluctuation-based modulation of input-output responses is not a universal feature of neurons and can be significantly limited by subthreshold voltage-gated conductances. PMID:25909971

  6. Beta-Estradiol Regulates Voltage-Gated Calcium Channels and Estrogen Receptors in Telocytes from Human Myometrium

    Directory of Open Access Journals (Sweden)

    Adela Banciu

    2018-05-01

    Full Text Available Voltage-gated calcium channels and estrogen receptors are essential players in uterine physiology, and their association with different calcium signaling pathways contributes to healthy and pathological conditions of the uterine myometrium. Among the properties of the various cell subtypes present in human uterine myometrium, there is increasing evidence that calcium oscillations in telocytes (TCs contribute to contractile activity and pregnancy. Our study aimed to evaluate the effects of beta-estradiol on voltage-gated calcium channels and estrogen receptors in TCs from human uterine myometrium and to understand their role in pregnancy. For this purpose, we employed patch-clamp recordings, ratiometric Fura-2-based calcium imaging analysis, and qRT-PCR techniques for the analysis of cultured human myometrial TCs derived from pregnant and non-pregnant uterine samples. In human myometrial TCs from both non-pregnant and pregnant uterus, we evidenced by qRT-PCR the presence of genes encoding for voltage-gated calcium channels (Cav3.1, Ca3.2, Cav3.3, Cav2.1, estrogen receptors (ESR1, ESR2, GPR30, and nuclear receptor coactivator 3 (NCOA3. Pregnancy significantly upregulated Cav3.1 and downregulated Cav3.2, Cav3.3, ESR1, ESR2, and NCOA3, compared to the non-pregnant condition. Beta-estradiol treatment (24 h, 10, 100, 1000 nM downregulated Cav3.2, Cav3.3, Cav1.2, ESR1, ESR2, GRP30, and NCOA3 in TCs from human pregnant uterine myometrium. We also confirmed the functional expression of voltage-gated calcium channels by patch-clamp recordings and calcium imaging analysis of TCs from pregnant human myometrium by perfusing with BAY K8644, which induced calcium influx through these channels. Additionally, we demonstrated that beta-estradiol (1000 nM antagonized the effect of BAY K8644 (2.5 or 5 µM in the same preparations. In conclusion, we evidenced the presence of voltage-gated calcium channels and estrogen receptors in TCs from non-pregnant and pregnant

  7. Beta-Estradiol Regulates Voltage-Gated Calcium Channels and Estrogen Receptors in Telocytes from Human Myometrium.

    Science.gov (United States)

    Banciu, Adela; Banciu, Daniel Dumitru; Mustaciosu, Cosmin Catalin; Radu, Mihai; Cretoiu, Dragos; Xiao, Junjie; Cretoiu, Sanda Maria; Suciu, Nicolae; Radu, Beatrice Mihaela

    2018-05-09

    Voltage-gated calcium channels and estrogen receptors are essential players in uterine physiology, and their association with different calcium signaling pathways contributes to healthy and pathological conditions of the uterine myometrium. Among the properties of the various cell subtypes present in human uterine myometrium, there is increasing evidence that calcium oscillations in telocytes (TCs) contribute to contractile activity and pregnancy. Our study aimed to evaluate the effects of beta-estradiol on voltage-gated calcium channels and estrogen receptors in TCs from human uterine myometrium and to understand their role in pregnancy. For this purpose, we employed patch-clamp recordings, ratiometric Fura-2-based calcium imaging analysis, and qRT-PCR techniques for the analysis of cultured human myometrial TCs derived from pregnant and non-pregnant uterine samples. In human myometrial TCs from both non-pregnant and pregnant uterus, we evidenced by qRT-PCR the presence of genes encoding for voltage-gated calcium channels (Cav3.1, Ca3.2, Cav3.3, Cav2.1), estrogen receptors (ESR1, ESR2, GPR30), and nuclear receptor coactivator 3 (NCOA3). Pregnancy significantly upregulated Cav3.1 and downregulated Cav3.2, Cav3.3, ESR1, ESR2, and NCOA3, compared to the non-pregnant condition. Beta-estradiol treatment (24 h, 10, 100, 1000 nM) downregulated Cav3.2, Cav3.3, Cav1.2, ESR1, ESR2, GRP30, and NCOA3 in TCs from human pregnant uterine myometrium. We also confirmed the functional expression of voltage-gated calcium channels by patch-clamp recordings and calcium imaging analysis of TCs from pregnant human myometrium by perfusing with BAY K8644, which induced calcium influx through these channels. Additionally, we demonstrated that beta-estradiol (1000 nM) antagonized the effect of BAY K8644 (2.5 or 5 µM) in the same preparations. In conclusion, we evidenced the presence of voltage-gated calcium channels and estrogen receptors in TCs from non-pregnant and pregnant human uterine

  8. Supervision and control of grid connected PV-Storage systems with the five level diode clamped inverter

    International Nuclear Information System (INIS)

    Himour, Kamal; Ghedamsi, Kaci; Berkouk, El Madjid

    2014-01-01

    Highlights: • Use of battery bank in grid connection photovoltaic system to ensure the energetic autonomy of the system. • Improve the quality of energy by the use of five-level inverter in a grid connection PV generation system. • Control of inverter by fast and simplified space vector pulse width modulation. • Control and supervision of active and reactive power in the grid. - Abstract: This paper aimed to evaluate the use of photovoltaic-battery storage systems to supply electric power in the distribution grid through a multilevel inverter. The proposed system is composed by four PV generators with MPPT (P and O) control, four battery storage systems connected to each capacitor of the DC link and a five level diode clamped inverter connected to the grid by a traditional three phase transformer. The proposed control has a hierarchical structure with both a grid side control level to regulate the power and the current injected to the grid and four input side regulation units. The system operator controls the power production of the four PV generators by sending out reference power signals to each input side regulation unit, the input side regulation units regulate the voltage of each capacitor of the DC link, regulate the voltage and the state of charge of each battery storage system

  9. 21 CFR 882.5175 - Carotid artery clamp.

    Science.gov (United States)

    2010-04-01

    ... (the principal artery in the neck that supplies blood to the brain) and has a removable adjusting mechanism that protrudes through the skin of the patient's neck. The clamp is used to occlude the patient's... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED...

  10. Field angle dependence of voltage-induced ferromagnetic resonance under DC bias voltage

    International Nuclear Information System (INIS)

    Shiota, Yoichi; Miwa, Shinji; Tamaru, Shingo; Nozaki, Takayuki; Kubota, Hitoshi; Fukushima, Akio; Suzuki, Yoshishige; Yuasa, Shinji

    2016-01-01

    We studied the rectification function of microwaves in CoFeB/MgO-based magnetic tunnel junctions using voltage-induced ferromagnetic resonance (FMR). Our findings reveal that the shape of the structure of the spectrum depends on the rotation angle of the external magnetic field, providing clear evidence that FMR dynamics are excited by voltage-induced magnetic anisotropy changes. Further, enhancement of the rectified voltage was demonstrated under a DC bias voltage. In our experiments, the highest microwave detection sensitivity obtained was 350 mV/mW, at an RF frequency of 1.0 GHz and field angle of θ_H=80°, ϕ_H=0°. The experimental results correlated with those obtained via simulation, and the calculated results revealed the magnetization dynamics at the resonance state. - Highlights: • Examined voltage-induced ferromagnetic resonance (FMR) under various field angles. • FMR dynamics are excited by voltage-induced magnetic anisotropy changes. • Microwave detection sensitivity depends on input RF and elevation angle. • Microwave detection sensitivity=350 mV/mW at RF=1.0 GHz, θ_H=80°, ϕ_H=0°.

  11. Analysis and testing of the DIII-D ohmic heating coil lead repair clamp

    International Nuclear Information System (INIS)

    Reis, E.E.; Anderson, P.M.; Chin, E.; Robinson, J.I.

    1997-11-01

    DIII-D has been operating for the last year with limited volt-second capabilities due to structural failure of a conductor lead to one of the ohmic heating (OH) solenoids. The conductor failure was due to poor epoxy impregnation of the overwrap of the lead pack, resulting in copper fatigue and a water leak. A number of structural analyses were performed to assist in determining the failure scenario and to evaluate various repair options. A fatigue stress analysis of the leads with a failed epoxy overwrap indicated crack initiation after 1,000 cycles at the maximum operating conditions. The failure occurred in a very inaccessible area which restricted design repair options to concepts which could be implemented remotely. Several design options were considered for repairing the lead so that it can sustain the loads for 7.5 Vs conditions at full toroidal field. A clamp, along with preloaded banding straps and shim bags, provides a system that guarantees that the stress at the crack location is always compressive and prevents further crack growth in the conductor. Due to the limited space available for the repair, it was necessary to design the clamp system to operate at the material yield stress. The primary components of the clamp system were verified by load tests prior to installation. The main body of the clamp contains a load cell and potentiometer for monitoring the load-deflection characteristics of the clamp and conductors during plasma operation. Strain gages provides redundant instrumentation. If required, the preload on the conductors can be increased remotely by a special wrench attached to the clamp assembly

  12. Lack of direct evidence for a functional role of voltage-operated calcium channels in juxtaglomerular cells

    DEFF Research Database (Denmark)

    Kurtz, A; Skott, O; Chegini, S

    1990-01-01

    in patch-clamped nor in intact Furaester-loaded cells. Moreover, basal renin secretion from a preparation enriched in mouse juxtaglomerular cells and from rat glomeruli with attached juxtaglomerular cells was not inhibited when extracellular potassium was isoosmotically increased to 56 mmol/l. In mouse...... kidney slices, however, depolarizing potassium concentrations caused a delayed inhibition at 56 mmol/l and a delayed stimulation of renin secretion at 110 mmol/l. Taken together, our study does not provide direct evidence for a role of voltage-activated calcium channels in the regulation of calcium...

  13. Molecular determinants of voltage-gated sodium channel regulation by the Nedd4/Nedd4-like proteins

    DEFF Research Database (Denmark)

    Rougier, Jean-Sébastien; van Bemmelen, Miguel X; Bruce, M Christine

    2004-01-01

    -ubiquitin ligases of the Nedd4 family. We recently reported that cardiac Na(v)1.5 is regulated by Nedd4-2. In this study, we further investigated the molecular determinants of regulation of Na(v) proteins. When expressed in HEK-293 cells and studied using whole cell voltage clamping, the neuronal Na(v)1.2 and Na...... that Nedd4-dependent ubiquitination of Na(v) channels may represent a general mechanism regulating the excitability of neurons and myocytes via modulation of channel density at the plasma membrane....

  14. NO involvement in the inhibition of ghrelin on voltage-dependent potassium currents in rat hippocampal cells.

    Science.gov (United States)

    Lu, Yong; Dang, Shaokang; Wang, Xu; Zhang, Junli; Zhang, Lin; Su, Qian; Zhang, Huiping; Lin, Tianwei; Zhang, Xiaoxiao; Zhang, Yurong; Sun, Hongli; Zhu, Zhongliang; Li, Hui

    2018-01-01

    Ghrelin is a peptide hormone that plays an important role in promoting appetite, regulating distribution and rate of use of energy, cognition, and mood disorders, but the relevant neural mechanisms of these function are still not clear. In this study, we examined the effect of ghrelin on voltage-dependent potassium (K + ) currents in hippocampal cells of 1-3 days SD rats by whole-cell patch-clamp technique, and discussed whether NO was involved in this process. The results showed that ghrelin significantly inhibited the voltage-dependent K + currents in hippocampal cells, and the inhibitory effect was more significant when l-arginine was co-administered. In contrast, N-nitro- l-arginine methyl ester increased the ghrelin inhibited K + currents and attenuated the inhibitory effect of ghrelin. While d-arginine (D-AA) showed no significant impact on the ghrelin-induced decrease in K + current. These results show that ghrelin may play a physiological role by inhibiting hippocampal voltage dependent K + currents, and the NO pathway may be involved in this process. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Effect of ciguatoxin 3C on voltage-gated Na+ and K+ currents in mouse taste cells.

    Science.gov (United States)

    Ghiaroni, Valeria; Fuwa, Haruhiko; Inoue, Masayuki; Sasaki, Makoto; Miyazaki, Keisuke; Hirama, Masahiro; Yasumoto, Takeshi; Rossini, Gian Paolo; Scalera, Giuseppe; Bigiani, Albertino

    2006-09-01

    The marine dinoflagellate Gambierdiscus toxicus produces highly lipophilic, polycyclic ether toxins that cause a seafood poisoning called ciguatera. Ciguatoxins (CTXs) and gambierol represent the two major causative agents of ciguatera intoxication, which include taste alterations (dysgeusiae). However, information on the mode of action of ciguatera toxins in taste cells is scarce. Here, we have studied the effect of synthetic CTX3C (a CTX congener) on mouse taste cells. By using the patch-clamp technique to monitor membrane ion currents, we found that CTX3C markedly affected the operation of voltage-gated Na(+) channels but was ineffective on voltage-gated K(+) channels. This result was the exact opposite of what we obtained earlier with gambierol, which inhibits K(+) channels but not Na(+) channels. Thus, CTXs and gambierol affect with high potency the operation of separate classes of voltage-gated ion channels in taste cells. Our data suggest that taste disturbances reported in ciguatera poisoning might be due to the ability of ciguatera toxins to interfere with ion channels in taste buds.

  16. Ventilation before Umbilical Cord Clamping improves the physiological transition at birth.

    Directory of Open Access Journals (Sweden)

    Sasmira eBhatt

    2014-10-01

    Full Text Available The transition from a fetus to a neonate at birth represents a critical phase in our life. Most infants make this transition without complications, but preterm infants usually require some form of assistance due to immature cardiopulmonary systems that predispose them to lifelong sequelae. As the incidence of preterm birth is increasing, there is now an urgent need for the development of management strategies that facilitate this transition, which will likely include improved strategies for the management of the maternal third stage of labour. For instance, recent studies on the physiological transition at birth have led to the discovery that establishing ventilation in the infant before the umbilical cord is clamped greatly stabilizes the cardiovascular transition at birth. While most benefits of delayed clamping have previously been attributed to an increase in placenta to infant blood transfusion, clearly there are other significant benefits for the infant, which are not well understood. Nevertheless, if ventilation can be established before cord clamping in a preterm infant, the large adverse changes in cardiac function that normally accompanies umbilical cord clamping can be avoided. As preterm infants have an immature cerebral vascular bed, large swings in cardiovascular function places them at high risk of cerebral vascular rupture and the associated increased risk of mortality and morbidity. In view of the impact that cord clamping has on the cardiovascular transition at birth, it is also time to re-examine some of the strategies used in the management of the third stage of labour. These include the appropriate timing of uterotonic administration in relation to delivery of the infant and placenta. As there is a lack of evidence on the effects these individual practices have on the infant, there is a necessity to improve our understanding of their impact in order to develop strategies that facilitate the transition to newborn life.

  17. CLAMP - a toolkit for efficiently building customized clinical natural language processing pipelines.

    Science.gov (United States)

    Soysal, Ergin; Wang, Jingqi; Jiang, Min; Wu, Yonghui; Pakhomov, Serguei; Liu, Hongfang; Xu, Hua

    2017-11-24

    Existing general clinical natural language processing (NLP) systems such as MetaMap and Clinical Text Analysis and Knowledge Extraction System have been successfully applied to information extraction from clinical text. However, end users often have to customize existing systems for their individual tasks, which can require substantial NLP skills. Here we present CLAMP (Clinical Language Annotation, Modeling, and Processing), a newly developed clinical NLP toolkit that provides not only state-of-the-art NLP components, but also a user-friendly graphic user interface that can help users quickly build customized NLP pipelines for their individual applications. Our evaluation shows that the CLAMP default pipeline achieved good performance on named entity recognition and concept encoding. We also demonstrate the efficiency of the CLAMP graphic user interface in building customized, high-performance NLP pipelines with 2 use cases, extracting smoking status and lab test values. CLAMP is publicly available for research use, and we believe it is a unique asset for the clinical NLP community. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Square-Wave Voltage Injection Algorithm for PMSM Position Sensorless Control With High Robustness to Voltage Errors

    DEFF Research Database (Denmark)

    Ni, Ronggang; Xu, Dianguo; Blaabjerg, Frede

    2017-01-01

    relationship with the magnetic field distortion. Position estimation errors caused by higher order harmonic inductances and voltage harmonics generated by the SVPWM are also discussed. Both simulations and experiments are carried out based on a commercial PMSM to verify the superiority of the proposed method......Rotor position estimated with high-frequency (HF) voltage injection methods can be distorted by voltage errors due to inverter nonlinearities, motor resistance, and rotational voltage drops, etc. This paper proposes an improved HF square-wave voltage injection algorithm, which is robust to voltage...... errors without any compensations meanwhile has less fluctuation in the position estimation error. The average position estimation error is investigated based on the analysis of phase harmonic inductances, and deduced in the form of the phase shift of the second-order harmonic inductances to derive its...

  19. Effect of complete hilar versus only renal artery clamping on renal histomorphology following ischemia/reperfusion injury in an experimental model.

    Science.gov (United States)

    Umul, M; Cal, A C; Turna, B; Oktem, G; Aydın, H H

    2016-01-01

    To evaluate the effect of temporary complete hilar versus only renal artery clamping with different duration of warm ischemia on renal functions, and possibly identify a "safe" clamping type and duration of renal ischemia. Fifty male rabbits have been incorporated to study. Rabbits were subjected to ischemia/reperfusion injury by temporary vascular clamping. Reagents were randomized to 3 experimental groups (only renal artery clamping, complete hilar clamping, sham surgery) and sub-groups were determined according to different clamping times (30 and 60 minutes). Median laparotomy and left renal hilus dissection were performed to sham group. Only artery or complete hilar clamping was performed for 30 or 60 minutes by microvascular bulldog clamps to other reagents. Rabbits were sacrificed 10 days after primary surgery and left nephrectomy performed. Nephrectomy materials were evaluated for the level of nitric-oxide synthase (NOS) immunoreactivity, malondialdehyde (MDA) level and superoxide dismutase (SOD) activity and an electron microscopic examination was performed. NOS immunoreactivity was correlated with the temporary clamping time. We also observed that complete hilar vascular clamping entails an increase on NOS immunoreactivity. MDA levels were similar for all experimental surgery groups (p = 0.42). The SOD activity was decreased among all subgroups compared with sham surgery. But the significant decrease occurred in 30 minutes only artery and 30 minutes complete hilar clamping groups in proportion to sham surgery (p = 0.026 and p = 0.019, respectively). This current study suggested that only renal artery clamping under 30 minutes is more appropriate during renal surgical procedures requiring temporary vascular clamping.

  20. Voltage-assisted polymer wafer bonding

    International Nuclear Information System (INIS)

    Varsanik, J S; Bernstein, J J

    2012-01-01

    Polymer wafer bonding is a widely used process for fabrication of microfluidic devices. However, best practices for polymer bonds do not achieve sufficient bond strength for many applications. By applying a voltage to a polymer bond in a process called voltage-assisted bonding, bond strength is shown to improve dramatically for two polymers (Cytop™ and poly(methyl methacrylate)). Several experiments were performed to provide a starting point for further exploration of this technique. An optimal voltage range is experimentally observed with a reduction in bonding strength at higher voltages. Additionally, voltage-assisted bonding is shown to reduce void diameter due to bond defects. An electrostatic force model is proposed to explain the improved bond characteristics. This process can be used to improve bond strength for most polymers. (paper)

  1. Coexpression of voltage-dependent calcium channels Cav1.2, 2.1a, and 2.1b in vascular myocytes

    DEFF Research Database (Denmark)

    Andreasen, Ditte; Friis, Ulla G; Uhrenholt, Torben R

    2006-01-01

    Voltage-dependent Ca2+ channels Cav1.2 (L type) and Cav2.1 (P/Q type) are expressed in vascular smooth muscle cells (VSMCs) and are important for the contraction of renal resistance vessels. In the present study we examined whether native renal VSMCs coexpress L-, P-, and Q-type Ca2+ currents...... microscopy revealed expression of both channels in all of the smooth muscle cells. Whole-cell patch clamp on single preglomerular VSMCs from mice showed L-, P-, and Q-type currents. Blockade of the L-type currents by calciseptine (20 nmol/L) inhibited 35.6+/-3.9% of the voltage-dependent Ca2+ current......-type and P-type channels inhibited 58.0+/-11.8%, and simultaneous inhibition of L-, P-, and Q-type channels led to blockade (88.7+/-5.6%) of the Ca2+ current. We conclude that aortic and renal preglomerular smooth muscle cells express L-, P-, and Q-type voltage-dependent Ca2+ channels in the rat and mouse....

  2. Computing rates of Markov models of voltage-gated ion channels by inverting partial differential equations governing the probability density functions of the conducting and non-conducting states.

    Science.gov (United States)

    Tveito, Aslak; Lines, Glenn T; Edwards, Andrew G; McCulloch, Andrew

    2016-07-01

    Markov models are ubiquitously used to represent the function of single ion channels. However, solving the inverse problem to construct a Markov model of single channel dynamics from bilayer or patch-clamp recordings remains challenging, particularly for channels involving complex gating processes. Methods for solving the inverse problem are generally based on data from voltage clamp measurements. Here, we describe an alternative approach to this problem based on measurements of voltage traces. The voltage traces define probability density functions of the functional states of an ion channel. These probability density functions can also be computed by solving a deterministic system of partial differential equations. The inversion is based on tuning the rates of the Markov models used in the deterministic system of partial differential equations such that the solution mimics the properties of the probability density function gathered from (pseudo) experimental data as well as possible. The optimization is done by defining a cost function to measure the difference between the deterministic solution and the solution based on experimental data. By evoking the properties of this function, it is possible to infer whether the rates of the Markov model are identifiable by our method. We present applications to Markov model well-known from the literature. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  3. High voltage K/sub a/-band gyrotron oscillator experiment

    International Nuclear Information System (INIS)

    Gold, S.H.; Fliflet, A.W.; Manheimer, W.M.; Black, W.M.; Granatstein, V.L.; Kinkead, A.K.; Hardesty, D.L.; Sucy, M.

    1986-01-01

    Future applications of millimeter-waves may require significantly higher powers (>100 MW) than are available from the long-pulse thermionic gyrotrons that are presently available or under development. Scaling studies suggest that these power levels should be accessible to gyrotrons employing relativistic (0.5-1 MeV), multi-kA electron beams, such as can be generated for short pulse lengths (≤100 nsec) using pulseline accelerators with plasma-induced field-emission cathodes. To explore this potential, the authors have assembled a new gyrotron experiment based on a compact Febetron pulser. Initial experiments using a 350keV, 700A electron beam with a ratio of transverse to longitudinal velocity of ≅0.75 have produced ≅20MW at 35GHz at 8.5% efficiency in a TE/sub 62/ mode, in good agreement with the predictions of theory for the experimental parameters. Substantially higher powers and efficiencies are predicted for a new experimental configuration, which will operate at a higher voltage with improved beam parameters. In this new experiment, a 600 keV, multi-kA electron beam will be produced with low initial transverse energy. Transverse kinetic energy will then be added to the beam either by resonant pumping, via a magnetic wiggler, or by transit through a nonadiabatic magnetic ''bump.'' Finally, the beam will be adiabatically compressed to the desired radius in the gyrotron cavity with a final α≅1. The authors plan to report on the latest results from this new experimental configuration

  4. Substrate clamping effects on irreversible domain wall dynamics in lead zirconate titanate thin films.

    Science.gov (United States)

    Griggio, F; Jesse, S; Kumar, A; Ovchinnikov, O; Kim, H; Jackson, T N; Damjanovic, D; Kalinin, S V; Trolier-McKinstry, S

    2012-04-13

    The role of long-range strain interactions on domain wall dynamics is explored through macroscopic and local measurements of nonlinear behavior in mechanically clamped and released polycrystalline lead zirconate-titanate (PZT) films. Released films show a dramatic change in the global dielectric nonlinearity and its frequency dependence as a function of mechanical clamping. Furthermore, we observe a transition from strong clustering of the nonlinear response for the clamped case to almost uniform nonlinearity for the released film. This behavior is ascribed to increased mobility of domain walls. These results suggest the dominant role of collective strain interactions mediated by the local and global mechanical boundary conditions on the domain wall dynamics. The work presented in this Letter demonstrates that measurements on clamped films may considerably underestimate the piezoelectric coefficients and coupling constants of released structures used in microelectromechanical systems, energy harvesting systems, and microrobots.

  5. Γ-source Neutral Point Clamped Inverter

    DEFF Research Database (Denmark)

    Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede

    Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress...... and better output performance comparing with traditional two-level inverters. Integrating these two types of configurations can help neutral point inverters achieve enhanced votlage buck-boost capability....

  6. Constant-frequency, clamped-mode resonant converters

    Science.gov (United States)

    Tsai, Fu-Sheng; Materu, Peter; Lee, Fred C.

    1987-01-01

    Two novel clamped-mode resonant converters are proposed which operate at a constant frequency while retaining many desired features of conventional series- and parallel-resonant converters. State-plane analysis techniques are used to identify all possible operating modes and define their mode boundaries. Control-to-output characteristics are derived that specify the regions for natural and forced commutation. The predicted operating modes are verified using a prototype circuit.

  7. Voltage-gated lipid ion channels

    DEFF Research Database (Denmark)

    Blicher, Andreas; Heimburg, Thomas Rainer

    2013-01-01

    Synthetic lipid membranes can display channel-like ion conduction events even in the absence of proteins. We show here that these events are voltage-gated with a quadratic voltage dependence as expected from electrostatic theory of capacitors. To this end, we recorded channel traces and current...... histograms in patch-experiments on lipid membranes. We derived a theoretical current-voltage relationship for pores in lipid membranes that describes the experimental data very well when assuming an asymmetric membrane. We determined the equilibrium constant between closed and open state and the open...... probability as a function of voltage. The voltage-dependence of the lipid pores is found comparable to that of protein channels. Lifetime distributions of open and closed events indicate that the channel open distribution does not follow exponential statistics but rather power law behavior for long open times...

  8. The experiment of grid characteristics for high-voltage radiography of chest

    International Nuclear Information System (INIS)

    Kim, Jung Min; Ahn, Bong Seon

    1992-01-01

    Grids can improve the diagnostic quality of chest radiography by trapping the greater part of scattered radiation thus providing more detailed chest radiographic images. It is most effective method of reduce the scatter ratio but must increase the expour factor. The benefit of use of grid is improve the contrast and the loss is increase of patient dose. In chest radiography especially hard quality high voltage radiography it will have to be considered to select the optimum grid with view point of benefit and loss. In this experiment, auther got some result of characteristics about 4 different grids with film method. 1. There was no difference the scatter ratio in case of no grid and the scatter ratio was about 60 % 2. 16 : 1 grid was excellent of scatter reduction factor in high voltage chest radiography, next was 10 : 1, CROSS, MICRO FINE grid have low scatter reduction rate compare to 16:1,10:1 grid. 3. The bucky factor of CROSS grid in accordance of kVp was find out the highest in 4 grids, on the contrary 10 : 1 grid was profitable to the. exposure does. 4. With careful consideration in the point of scatter reduction rate and bucky factor, auther suggest the 10 : 1 linear grid on the use of chest radiography in 80∼120 kVp, 16 : 1 grid in 120∼140 kVp

  9. The optimal protocol to reduce blood loss and blood transfusion after unilateral total knee replacement: Low-dose IA-TXA plus 30-min drain clamping versus drainage clamping for the first 3 h without IA-TXA.

    Science.gov (United States)

    Park, Joo Hyun; Choi, Sung Wook; Shin, Eun Ho; Park, Myung Hoon; Kim, Myung Ku

    2017-01-01

    Although intraarticular tranexamic acid (IA-TXA) administration or drainage clamping are popular methods used to reduce blood loss after total knee replacement (TKR), the protocol remains controversial. We aimed (1) to establish new protocols through investigating whether two methods, that is, low-dose (500 mg) IA-TXA plus 30-min drain clamping and drainage clamping for the first 3 h without IA-TXA, can reduce blood loss and blood transfusion after unilateral TKR and (2) to make recommendations related to clinical application. This study, conducted from September 2014 to June 2016 related to enrolled 95 patients with primary osteoarthritis who were to have a unilateral cemented TKR, was nonrandomized and retrospective. In group A, the drain was released following tourniquet deflation. In group B, 500-mg TXA was injected into the knee joint via a drain tube after fascia closure and the drain was clamped for the first 30 min to prevent leakage. In group C, the drain was clamped for the first 3-h postoperation. Demographic characteristics and clinical data were collected, including the levels of hematocrit (Hct), the total blood loss (TBL), drained blood volume (BV), the amount of blood transfused, and any complications that developed. We found a significantly lower postoperative TBL, drained BV, decreasing Hct level, and less transfused BV in the IA-TXA injection group (group B) and the 3-h drainage clamping group (group C) compared to the conventional negative drainage group (group A; p optimal than drainage clamping in patients with high bleeding tendency or lateral retinacular release during TKR, who would be concerned about postoperative wound complication.

  10. Robotic Automation of In Vivo Two-Photon Targeted Whole-Cell Patch-Clamp Electrophysiology.

    Science.gov (United States)

    Annecchino, Luca A; Morris, Alexander R; Copeland, Caroline S; Agabi, Oshiorenoya E; Chadderton, Paul; Schultz, Simon R

    2017-08-30

    Whole-cell patch-clamp electrophysiological recording is a powerful technique for studying cellular function. While in vivo patch-clamp recording has recently benefited from automation, it is normally performed "blind," meaning that throughput for sampling some genetically or morphologically defined cell types is unacceptably low. One solution to this problem is to use two-photon microscopy to target fluorescently labeled neurons. Combining this with robotic automation is difficult, however, as micropipette penetration induces tissue deformation, moving target cells from their initial location. Here we describe a platform for automated two-photon targeted patch-clamp recording, which solves this problem by making use of a closed loop visual servo algorithm. Our system keeps the target cell in focus while iteratively adjusting the pipette approach trajectory to compensate for tissue motion. We demonstrate platform validation with patch-clamp recordings from a variety of cells in the mouse neocortex and cerebellum. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Control of local intracellular calcium concentration with dynamic-clamp controlled 2-photon uncaging.

    Directory of Open Access Journals (Sweden)

    Erwin Idoux

    Full Text Available The variations of the intracellular concentration of calcium ion ([Ca(2+](i are at the heart of intracellular signaling, and their imaging is therefore of enormous interest. However, passive [Ca(2+](i imaging provides no control over these variations, meaning that a full exploration of the functional consequences of [Ca(2+](i changes is difficult to attain. The tools designed so far to modify [Ca(2+](i, even qualitatively, suffer drawbacks that undermine their widespread use. Here, we describe an electro-optical technique to quantitatively set [Ca(2+](i, in real time and with sub-cellular resolution, using two-photon Ca(2+ uncaging and dynamic-clamp. We experimentally demonstrate, on neurons from acute olfactory bulb slices of Long Evans rats, various capabilities of this technique previously difficult to achieve, such as the independent control of the membrane potential and [Ca(2+](i variations, the functional knocking-in of user-defined virtual voltage-dependent Ca(2+ channels, and the standardization of [Ca(2+](i patterns across different cells. Our goal is to lay the groundwork for this technique and establish it as a new and versatile tool for the study of cell signaling.

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

    Directory of Open Access Journals (Sweden)

    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.

  13. Design of A Grid Integrated PV System with MPPT Control and Voltage Oriented Controller using MATLAB/PLECES

    Science.gov (United States)

    Soreng, Bineeta; Behera, Pradyumna; Pradhan, Raseswari

    2017-08-01

    This paper presents model of a grid-integrated photovoltaic array with Maximum Power Point Tracker (MPPT) and voltage oriented controller. The MPPT of the PV array is usually an essential part of PV system as MPPT helps the operating point of the solar array to align its maximum power point. In this model, the MPPT along with a DC-DC converter lets a PV generator to produce continuous power, despite of the measurement conditions. The neutral-point-clamped converter (NPC) with a boost converter raises the voltage from the panels to the DC-link. An LCL-filter smoothens the current ripple caused by the PWM modulation of the grid-side inverter. In addition to the MPPT, the system has two more two controllers, such as voltage controller and a current controller. The voltage control has a PI controller to regulate the PV voltage to optimal level by controlling the amount of current injected into the boost stage. Here, the grid-side converter transfers the power from the DC-link into the grid and maintains the DC-link voltage. Three-phase PV inverters are used for off-grid or designed to create utility frequency AC. The PV system can be connected in series or parallel to get the desired output power. To justify the working of this model, the grid-integrated PV system has been designed in MATLAB/PLECS. The simulation shows the P-V curve of implemented PV Array consisting 4 X 20 modules, reactive, real power, grid voltage and current.

  14. Experimental determination of optimal clamping torque for AB-PEM Fuel cell

    Directory of Open Access Journals (Sweden)

    Noor Ul Hassan

    2016-04-01

    Full Text Available Polymer electrolyte Membrane (PEM fuel cell is an electrochemical device producing electricity by the reaction of hydrogen and oxygen without combustion. PEM fuel cell stack is provided with an appropriate clamping torque to prevent leakage of reactant gases and to minimize the contact resistance between gas diffusion media (GDL and bipolar plates. GDL porous structure and gas permeability is directly affected by the compaction pressure which, consequently, drastically change the fuel cell performance. Various efforts were made to determine the optimal compaction pressure and pressure distributions through simulations and experimentation. Lower compaction pressure results in increase of contact resistance and also chances of leakage. On the other hand, higher compaction pressure decreases the contact resistance but also narrows down the diffusion path for mass transfer from gas channels to the catalyst layers, consequently, lowering cell performance. The optimal cell performance is related to the gasket thickness and compression pressure on GDL. Every stack has a unique assembly pressure due to differences in fuel cell components material and stack design. Therefore, there is still need to determine the optimal torque value for getting the optimal cell performance. This study has been carried out in continuation of deve­lopment of Air breathing PEM fuel cell for small Unmanned Aerial Vehicle (UAV application. Compaction pressure at minimum contact resistance was determined and clamping torque value was calcu­la­ted accordingly. Single cell performance tests were performed at five different clamping torque values i.e 0.5, 1.0, 1.5, 2.0 and 2.5 N m, for achieving optimal cell per­formance. Clamping pressure distribution tests were also performed at these torque values to verify uniform pressure distribution at optimal torque value. Experimental and theoretical results were compared for making inferences about optimal cell perfor­man­ce. A

  15. Triple Line-Voltage Cascaded VIENNA Converter Applied as the Medium-Voltage AC Drive

    Directory of Open Access Journals (Sweden)

    Jia Zou

    2018-04-01

    Full Text Available A novel rectifier based on a triple line-voltage cascaded VIENNA converter (LVC-VC was proposed. Compared to the conventional cascaded H-bridge converters, the switch voltage stress is lower, and the numbers of switches and dc capacitors are fewer under similar operating conditions in the proposed new multilevel converter. The modeling and control for the LVC-VC ware presented. Based on the analysis of the operation principle of the new converter, the power factor correction of the proposed converter was realized by employing a traditional one-cycle control strategy. The minimum average value and maximum harmonic components of the dc-link voltages of the three VIENNA rectifier modules ware calculated. Three VIENNA dc-link voltages were unbalanced under the unbalanced load conditions, so the zero sequence current was injected to the three inner currents for balancing three VIENNA dc-link voltages. Simulation and the results of the experiment verified the availability of the new proposed multilevel converter and the effectiveness of the corresponding control strategy applied.

  16. Combined acute hyperglycemic and hyperinsulinemic clamp induced profibrotic and proinflammatory responses in the kidney.

    Science.gov (United States)

    Mariappan, Meenalakshmi M; DeSilva, Kristin; Sorice, Gian Pio; Muscogiuri, Giovanna; Jimenez, Fabio; Ahuja, Seema; Barnes, Jefferey L; Choudhury, Goutam Ghosh; Musi, Nicolas; DeFronzo, Ralph; Kasinath, Balakuntalam S

    2014-02-01

    Increase in matrix protein content in the kidney is a cardinal feature of diabetic kidney disease. While renal matrix protein content is increased by chronic hyperglycemia, whether it is regulated by acute elevation of glucose and insulin has not been addressed. In this study, we aimed to evaluate whether short duration of combined hyperglycemia and hyperinsulinemia, mimicking the metabolic environment of prediabetes and early type 2 diabetes, induces kidney injury. Normal rats were subjected to either saline infusion (control, n = 4) or 7 h of combined hyperglycemic-hyperinsulinemic clamp (HG+HI clamp; n = 6). During the clamp, plasma glucose and plasma insulin were maintained at about 350 mg/dl and 16 ng/ml, respectively. HG+HI clamp increased the expression of renal cortical transforming growth factor-β (TGF-β) and renal matrix proteins, laminin and fibronectin. This was associated with the activation of SMAD3, Akt, mammalian target of rapamycin (mTOR) complexes, and ERK signaling pathways and their downstream target events in the initiation and elongation phases of mRNA translation, an important step in protein synthesis. Additionally, HG+HI clamp provoked renal inflammation as shown by the activation of Toll-like receptor 4 (TLR4) and infiltration of CD68-positive monocytes. Urinary F2t isoprostane excretion, an index of renal oxidant stress, was increased in the HG+HI clamp rats. We conclude that even a short duration of hyperglycemia and hyperinsulinemia contributes to activation of pathways that regulate matrix protein synthesis, inflammation, and oxidative stress in the kidney. This finding could have implications for the control of short-term rises in blood glucose in diabetic individuals at risk of developing kidney disease.

  17. MEMS-based clamp with a passive hold function for precision position retaining of micro manipulators

    International Nuclear Information System (INIS)

    Brouwer, D M; Van Dijk, J; Soemers, H M J R; De Jong, B R; De Boer, M J; Jansen, H V; Krijnen, G J M

    2009-01-01

    In this paper the design, modeling and fabrication of a precision MEMS-based clamp with a relatively large clamping force are presented. The purpose of the clamp is to mechanically fix a six-degree-of-freedom (DOF) MEMS-based sample manipulator (Brouwer et al J. Int. Soc. Precis. Eng. Nanotechnol. submitted) once the sample has been positioned in all DOFs. The clamping force is generated by a rotational electrostatic comb-drive actuator and can be latched passively by a parallel plate type electrostatically driven locking device. The clamp design is based on the principles of exact constraint design, resulting in a high actuation compliance (flexibility) combined with a high suspension stiffness. Therefore, a relatively large blocking force of 1.4 mN in relation to the used area of 1.8 mm 2 is obtained. The fabrication is based on silicon bulk micromachining technology and combines a high-aspect-ratio deep reactive ion etching (DRIE), conformal deposition of low-pressure chemical vapor deposition (LPCVD) silicon nitride and an anisotropic potassium hydroxide (KOH) backside etching technology. Special attention is given to void reduction of Si x N y trench isolation and reduction of heating phenomena during front-side release etching. Guidelines are given for the applied process. Measurements showed that the clamp was able to fix, hold and release a test actuator. The dynamic behavior was in good agreement with the modal analysis

  18. Evaluation of the clamping force in high tension bolt by using the ultrasonic nonlinearity

    International Nuclear Information System (INIS)

    Jang, Kyung Young; Cheon, Hae Wha; Ha, Hob; Park, Man Sick; Kim, No You

    2005-01-01

    High tension bolts have been used widely for the clamping of many kinds of large structure. Therefore, its estimation has been regarded as main issue in the maintenance of high tension bolts. This paper proposes a novel method using the ultrasonic nonlinearity, which is based on the dependency of sound speed on the stress. For this we introduce nonlinear elastic constants in the stress-strain relationship, and derive the sound speed as a linear function of stress. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out: The first one is to measure the sound speed when the bolt is stressed by the tension tester. The result showed good agreement with the expected linear relationship between the sound speed and the axial stress. The second one is to measure the sound speed when the bolt is stressed by the torque wrench. The results showed that the sound speed was decreased when the torque was increased. From these results we can say that the proposed method is enough useful to evaluate the clamping force in the high tension bolt.

  19. Enhancing endogenous stem cells in the newborn via delayed umbilical cord clamping

    Directory of Open Access Journals (Sweden)

    Christopher Lawton

    2015-01-01

    Full Text Available There is currently no consensus among clinicians and scientists over the appropriate or optimal timing for umbilical cord clamping. However, many clinical studies have suggested that delayed cord clamping is associated with various neonatal benefits including increased blood volume, reduced need for blood transfusion, increased cerebral oxygenation in pre-term infants, and decreased frequency of iron deficiency anemia in term infants. Human umbilical cord blood contains significant amounts of stem and progenitor cells and is currently used in the treatment of several life-threatening diseases. We propose that delayed cord clamping be encouraged as it enhances blood flow from the placenta to the neonate, which is accompanied by an increase supply of valuable stem and progenitor cells, as well as may improve blood oxygenation and increase blood volume, altogether reducing the infant′s susceptibility to both neonatal and age-related diseases.

  20. The evaluation on clamping force of high strength bolts by length parameter

    International Nuclear Information System (INIS)

    Kim, Kang-Seok; Nah, Hwan-Seon; Lee, Hyeon-Ju; Lee, Kang-Min

    2009-01-01

    It has been reported that the length parameter of high strength bolts results in the variance in tension loads. The required turn for each length is specified in AISC RCSC specification. This study was focused on evaluating any influence on the clamping torque subjected to length parameter of high strength bolts. The two kinds of high strength bolts of specimen are as follows; High Strength Hexagon bolt defined on ASTM A490 and Torque Shear Bolt on KS B 2819. The length parameter ranged from 60mm(3d) to 140mm(7d). The torque, turn of nut and the clamping force were analyzed to review whether length parameter can be affected on the required tension load. To test whether the length parameter has an impact on the torque and turn of nut for the required strength and clamping force, statistical analysis is carried out. (author)

  1. Thermodynamic basis for engineering high-affinity, high-specificity binding-induced DNA clamp nanoswitches.

    Science.gov (United States)

    Idili, Andrea; Plaxco, Kevin W; Vallée-Bélisle, Alexis; Ricci, Francesco

    2013-12-23

    Naturally occurring chemoreceptors almost invariably employ structure-switching mechanisms, an observation that has inspired the use of biomolecular switches in a wide range of artificial technologies in the areas of diagnostics, imaging, and synthetic biology. In one mechanism for generating such behavior, clamp-based switching, binding occurs via the clamplike embrace of two recognition elements onto a single target molecule. In addition to coupling recognition with a large conformational change, this mechanism offers a second advantage: it improves both affinity and specificity simultaneously. To explore the physics of such switches we have dissected here the thermodynamics of a clamp-switch that recognizes a target DNA sequence through both Watson-Crick base pairing and triplex-forming Hoogsteen interactions. When compared to the equivalent linear DNA probe (which relies solely on Watson-Crick interactions), the extra Hoogsteen interactions in the DNA clamp-switch increase the probe's affinity for its target by ∼0.29 ± 0.02 kcal/mol/base. The Hoogsteen interactions of the clamp-switch likewise provide an additional specificity check that increases the discrimination efficiency toward a single-base mismatch by 1.2 ± 0.2 kcal/mol. This, in turn, leads to a 10-fold improvement in the width of the "specificity window" of this probe relative to that of the equivalent linear probe. Given these attributes, clamp-switches should be of utility not only for sensing applications but also, in the specific field of DNA nanotechnology, for applications calling for a better control over the building of nanostructures and nanomachines.

  2. Study and Experiment on Non-Contact Voltage Sensor Suitable for Three-Phase Transmission Line.

    Science.gov (United States)

    Zhou, Qiang; He, Wei; Xiao, Dongping; Li, Songnong; Zhou, Kongjun

    2015-12-30

    A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase difference exists between detection signal and voltage signal to be measured, and the detection signal cannot accurately and timely reflect the change of conductor voltage signal to be measured. By aiming at the current problems of electric transformation, based on electrostatic induction principle, this paper designed a non-contact voltage sensor and gained detection signal of the sensor through electrostatic coupling for the electric field generated by electric charges of the conductor to be measured. The insulation structure design of the sensor is simple and its volume is small; phase difference of sensor measurement is effectively reduced through optimization design of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage sensor was tested on the experimental platform of simulating three-phase transmission line. According to the result, the designed non-contact voltage sensor can realize accurate and real-time measurement for the conductor voltage. It can be applied to online monitoring for the voltage of three-phase transmission line or three-phase distribution network line, which is in accordance with the development direction of the smart grid.

  3. Reversible fastener clamp load monitor with continuous visual or remote readout

    Science.gov (United States)

    Hodge, Malcolm H.; Kausel, Theodore C., Jr.; Begley, Matthew R.

    1998-03-01

    SIMS has developed a simple means for detecting and monitoring both absolute and relative clamp load, or bolt tension, in fastener systems. More than twenty-five percent of automotive failures are known to be due to undetected loss of fastener clamp load. While the equivalent aerospace maintenance statistics are not known, the average automobile has 3,500 fasteners while a Boeing 747 has closer to one million. It is therefore anticipated that the new SensaBolt clamp load tracking system could find wide applications in the aerospace arena. We describe a visually-evident and retrofitted clamp load monitoring design which is based on the differential joint substrate compression at, and immediately adjacent to, the fastener location. This intrinsically-accurate indicator does not necessarily require alteration in either the bolt or nut geometries, thereby facilitating product introduction and retrofit in aging aircraft applications. In addition, SensaBolt's sole reliance on substrate compression renders it more accurate then torque wrench or turn-of-nut techniques. Readout may be accomplished by any of three principal methods: for those applications with ease of access to the sensor, loss of tension can be determined by direct visual inspection. Application of a standard wrench can then be made to restore the fastener's proper tightness, per the SensaBolt indicators. In those instances where line-of-sight is unimpeded and more formal inspection is desired, the SensaBolt may be interrogated by a laser scanner bar code reader. Finally, SensaBolt may be addressed by the SIMS fiber optic harness for those instances where full-time remote interrogation is desired.

  4. Gating of the two-pore cation channel AtTPC1 in the plant vacuole is based on a single voltage-sensing domain.

    Science.gov (United States)

    Jaślan, D; Mueller, T D; Becker, D; Schultz, J; Cuin, T A; Marten, I; Dreyer, I; Schönknecht, G; Hedrich, R

    2016-09-01

    The two-pore cation channel TPC1 operates as a dimeric channel in animal and plant endomembranes. Each subunit consists of two homologous Shaker-like halves, with 12 transmembrane domains in total (S1-S6, S7-S12). In plants, TPC1 channels reside in the vacuolar membrane, and upon voltage stimulation, give rise to the well-known slow-activating SV currents. Here, we combined bioinformatics, structure modelling, site-directed mutagenesis, and in planta patch clamp studies to elucidate the molecular mechanisms of voltage-dependent channel gating in TPC1 in its native plant background. Structure-function analysis of the Arabidopsis TPC1 channel in planta confirmed that helix S10 operates as the major voltage-sensing site, with Glu450 and Glu478 identified as possible ion-pair partners for voltage-sensing Arg537. The contribution of helix S4 to voltage sensing was found to be negligible. Several conserved negative residues on the luminal site contribute to calcium binding, stabilizing the closed channel. During evolution of plant TPC1s from two separate Shaker-like domains, the voltage-sensing function in the N-terminal Shaker-unit (S1-S4) vanished. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  5. A simple technique to measure regional cerebral blood flow during intravascular ballon clamping

    International Nuclear Information System (INIS)

    Furuhata, Shigeru; Kubo, Atsushi; Kawase, Takeshi; Ibata, Yukio; Toya, Shigeo

    1988-01-01

    A case of giant internal carotid ophthalmic aneurysm was presented. In order to clarify whether the patient could tolerate carotid occlusion, a ballon clamping test was performed before surgery. The cerebral blood flow was measured using early imaging by single photon emission computed tomography (SPECT) with N-isopropyl-(iodine-123)-p-iodoamphetamine ( 123 I-IMP). When the ballon clamping test was performed the tracer was injected, and scanning was performed 35 minutes after removing the catheter. This tracer enabled a 'memory of blood flow' during temporary ischemia to determine the character of quick diffusion and slow wash out, that could not be performed by other methods of cerebral blood flow measurement. SPECT with 123 I-IMP can simplify the measurement of cerebral blood flow during the balloon clamping test. (author)

  6. Interactions Between SNAP-25 and Synaptotagmin-1 Are Involved in Vesicle Priming, Clamping Spontaneous and Stimulating Evoked Neurotransmission

    DEFF Research Database (Denmark)

    Schupp, Melanie; Malsam, Jörg; Ruiter, Marvin

    2016-01-01

    between region I (vesicle priming) and region II (evoked release). Spontaneous release was disinhibited by region I mutations and found to correlate with defective complexin (Cpx) clamping in an in vitro fusion assay, pointing to an interdependent role of synaptotagmin and Cpx in release clamping...... triggering, depend on direct SNARE complex interaction. SIGNIFICANCE STATEMENT: The function of synaptotagmin-1 (syt-1):soluble NSF attachment protein receptor (SNARE) interactions during neurotransmission remains unclear. We mutated SNAP-25 within the recently identified region I and region II...... was disinhibited by region I mutation and found to correlate with defective complexin (Cpx) clamping in vitro, pointing to an interdependent role of synaptotagmin and Cpx in release clamping. Therefore, vesicle priming, clamping spontaneous release, and eliciting evoked release are three different functions of syt...

  7. The influence of the preliminary garter spring spacer simulator clamping force in the pressure tube spacer -calandria tube hook-up simulator aging behaviour

    International Nuclear Information System (INIS)

    Gyongyosi, T.; Deloreanu, G.; Puiu, D.; Corbescu, B.; Anghel, N.; Dinu, E.

    2016-01-01

    The garter spring spacer is a specially constructed torsion spring used to fit-out the CANDU 6 fuel channel. The pressure tube ageing decreases the gap to the calandria tube. Continuous gap decrease directly affects the garter spring spacers behavior during fuel channel assembly operation. The preliminary clamping force value of the garter spring spacer assembly is important for its ageing behavior. This paper briefly describes the experimental technological facilities used for conducted the experiments and highlights some of the important moments during an experiment carried out in laboratory conditions, without using pressurized boiled water and irradiation working conditions. The results analysis and some conclusions are outlined at the end, pointing out that a garter spring spacer preliminary clamping force increase reduces the vibration response signal amplitude, and does not lead to its relaxation. The paper is dedicated to specialists working in research and technological engineering. (authors)

  8. Isolated DC-DC Converter for Bidirectional Power Flow Controlling with Soft-Switching Feature and High Step-Up/Down Voltage Conversion

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2017-03-01

    Full Text Available In this paper, a novel isolated bidirectional DC-DC converter is proposed, which is able to accomplish high step-up/down voltage conversion. Therefore, it is suitable for hybrid electric vehicle, fuel cell vehicle, energy backup system, and grid-system applications. The proposed converter incorporates a coupled inductor to behave forward-and-flyback energy conversion for high voltage ratio and provide galvanic isolation. The energy stored in the leakage inductor of the coupled inductor can be recycled without the use of additional snubber mechanism or clamped circuit. No matter in step-up or step-down mode, all power switches can operate with soft switching. Moreover, there is a inherit feature that metal–oxide–semiconductor field-effect transistors (MOSFETs with smaller on-state resistance can be adopted because of lower voltage endurance at primary side. Operation principle, voltage ratio derivation, and inductor design are thoroughly described in this paper. In addition, a 1-kW prototype is implemented to validate the feasibility and correctness of the converter. Experimental results indicate that the peak efficiencies in step-up and step-down modes can be up to 95.4% and 93.6%, respectively.

  9. The project of autocontrol for CAEN high voltage systems in high energy physics experiments

    International Nuclear Information System (INIS)

    Qian Sen; Wang Zhimin; Chinese Academy of Sciences, Beijing; Cai Xiao; Wang Yifang; Zhang Jiawen; Yang Changgen

    2008-01-01

    Based on TCP/IP network communication techniques, CAMAC Bus Technology, PCI Bus Technology and RS232 Serial Communication Technique, we developed and established a serial of software in Linux or Win32 system to auto control these high voltage systems made by CAEN Company, which are always used in high energy physics experiments. The operator can use this software to control and monitor the system independently, or encapsulate it into the DAQ system to control the test system and acquire data synchronously and high-efficaciously. (authors)

  10. A matter of quantum voltages

    Energy Technology Data Exchange (ETDEWEB)

    Sellner, Bernhard; Kathmann, Shawn M., E-mail: Shawn.Kathmann@pnnl.gov [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

    2014-11-14

    Voltages inside matter are relevant to crystallization, materials science, biology, catalysis, and aqueous chemistry. The variation of voltages in matter can be measured by experiment, however, modern supercomputers allow the calculation of accurate quantum voltages with spatial resolutions of bulk systems well beyond what can currently be measured provided a sufficient level of theory is employed. Of particular interest is the Mean Inner Potential (V{sub o}) – the spatial average of these quantum voltages referenced to the vacuum. Here we establish a protocol to reliably evaluate V{sub o} from quantum calculations. Voltages are very sensitive to the distribution of electrons and provide metrics to understand interactions in condensed phases. In the present study, we find excellent agreement with measurements of V{sub o} for vitrified water and salt crystals and demonstrate the impact of covalent and ionic bonding as well as intermolecular/atomic interactions. Certain aspects in this regard are highlighted making use of simple model systems/approximations. Furthermore, we predict V{sub o} as well as the fluctuations of these voltages in aqueous NaCl electrolytes and characterize the changes in their behavior as the resolution increases below the size of atoms.

  11. Experiences in simulating and testing coordinated voltage control provided by multiple wind power plants

    Energy Technology Data Exchange (ETDEWEB)

    Arlaban, T.; Alonso, O.; Ortiz, D. [Acciona Windpower S.A. (Spain); Peiro, J.; Rivas, R. [Red Electrica de Espana SAU (Spain); Quinonez-Varela, G.; Lorenzo, P. [Acciona Energia S.A. (Spain)

    2011-07-01

    This document presents some field tests performed in a transmission system node in order to check the adequacy of voltage control performance by multiple wind power plants, with an overall capacity of 395 MW. It briefly explains the Spanish TSO motivation towards new voltage control requirements and the necessity of performing such tests in order to set the most convenient voltage control parameters and to verify the stable operation. It presents how different the voltage control capability between modern wind turbines (DFIG) and older ones (SCIG) specifically retrofitted for voltage control is. (orig.)

  12. Analytical study of the frequency shifts of micro and nano clamped–clamped beam resonators due to an added mass

    KAUST Repository

    Bouchaala, Adam M.

    2016-03-18

    We present analytical formulations to calculate the induced resonance frequency shifts of electrically actuated clamped–clamped micro and nano (Carbon nanotube) beams due to an added mass. Based on the Euler–Bernoulli beam theory, we investigate the linear dynamic responses of the beams added masses, which are modeled as discrete point masses. Analytical expressions based on perturbation techniques and a one-mode Galerkin approximation are developed to calculate accurately the frequency shifts under a DC voltage as a function of the added mass and position. The analytical results are compared to numerical solution of the eigenvalue problem. Results are shown for the fundamental as well as the higher-order modes of the beams. The results indicate a significant increase in the frequency shift, and hence the sensitivity of detection, when scaling down to nano scale and using higher-order modes. © 2016 Springer Science+Business Media Dordrecht

  13. Clamped seismic metamaterials: ultra-low frequency stop bands

    International Nuclear Information System (INIS)

    Achaoui, Y; Enoch, S; Guenneau, S; Antonakakis, T; Brûlé, S; Craster, R V

    2017-01-01

    The regularity of earthquakes, their destructive power, and the nuisance of ground vibration in urban environments, all motivate designs of defence structures to lessen the impact of seismic and ground vibration waves on buildings. Low frequency waves, in the range 1–10 Hz for earthquakes and up to a few tens of Hz for vibrations generated by human activities, cause a large amount of damage, or inconvenience; depending on the geological conditions they can travel considerable distances and may match the resonant fundamental frequency of buildings. The ultimate aim of any seismic metamaterial, or any other seismic shield, is to protect over this entire range of frequencies; the long wavelengths involved, and low frequency, have meant this has been unachievable to date. Notably this is scalable and the effects also hold for smaller devices in ultrasonics. There are three approaches to obtaining shielding effects: bragg scattering, locally resonant sub-wavelength inclusions and zero-frequency stop-band media. The former two have been explored, but the latter has not and is examined here. Elastic flexural waves, applicable in the mechanical vibrations of thin elastic plates, can be designed to have a broad zero-frequency stop-band using a periodic array of very small clamped circles. Inspired by this experimental and theoretical observation, all be it in a situation far removed from seismic waves, we demonstrate that it is possible to achieve elastic surface (Rayleigh) wave reflectors at very large wavelengths in structured soils modelled as a fully elastic layer periodically clamped to bedrock. We identify zero frequency stop-bands that only exist in the limit of columns of concrete clamped at their base to the bedrock. In a realistic configuration of a sedimentary basin 15 m deep we observe a zero frequency stop-band covering a broad frequency range of 0–30 Hz. (paper)

  14. Small Molecules for Early Endosome-Specific Patch Clamping.

    Science.gov (United States)

    Chen, Cheng-Chang; Butz, Elisabeth S; Chao, Yu-Kai; Grishchuk, Yulia; Becker, Lars; Heller, Stefan; Slaugenhaupt, Susan A; Biel, Martin; Wahl-Schott, Christian; Grimm, Christian

    2017-07-20

    To resolve the subcellular distribution of endolysosomal ion channels, we have established a novel experimental approach to selectively patch clamp Rab5 positive early endosomes (EE) versus Rab7/LAMP1-positive late endosomes/lysosomes (LE/LY). To functionally characterize ion channels in endolysosomal membranes with the patch-clamp technique, it is important to develop techniques to selectively enlarge the respective organelles. We found here that two small molecules, wortmannin and latrunculin B, enlarge Rab5-positive EE when combined but not Rab7-, LAMP1-, or Rab11 (RE)-positive vesicles. The two compounds act rapidly, specifically, and are readily applicable in contrast to genetic approaches or previously used compounds such as vacuolin, which enlarges EE, RE, and LE/LY. We apply this approach here to measure currents mediated by TRPML channels, in particular TRPML3, which we found to be functionally active in both EE and LE/LY in overexpressing cells as well as in endogenously expressing CD11b+ lung-tissue macrophages. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Heat-pump performance: voltage dip/sag, under-voltage and over-voltage

    Directory of Open Access Journals (Sweden)

    William J.B. Heffernan

    2014-12-01

    Full Text Available Reverse cycle air-source heat-pumps are an increasingly significant load in New Zealand and in many other countries. This has raised concern over the impact wide-spread use of heat-pumps may have on the grid. The characteristics of the loads connected to the power system are changing because of heat-pumps. Their performance during under-voltage events such as voltage dips has the potential to compound the event and possibly cause voltage collapse. In this study, results from testing six heat-pumps are presented to assess their performance at various voltages and hence their impact on voltage stability.

  16. Long-Time Choledochal Clamping in Wistar Rats Causes Biliary Obstruction Progressing to Hepatic Fibrosis.

    Science.gov (United States)

    Jorge, G D L; Tártaro, R R; Escanhoela, C A F; Boin, I D F S F

    2016-09-01

    Biliary complications are important causes of morbidity and mortality in patients undergoing hepatic surgery. The aim of the study was to evaluate late liver alterations after a long period of choledochal clamping in Wistar rats. Ten male Wistar rats, weighing 304 grams, anesthetized with sodium thiopental (25 mg/kg) and xylazine (10 mg/kg) intravenously, were distributed into 2 groups: the choledochal clamping group (CCG) and the operation sham group (OSG), with 5 animals each submitted to an abdominal incision. In the CCG, the choledochal was isolated, dissected, and clamped with a microvascular clamp for 40 minutes. After this occlusion time, the clamp was removed and the incision was closed. In the OSG the animals, under normal conditions, were submitted only to anesthesia and laparotomy for choledochal manipulation. In all animals, after the 31st day, a hepatic biopsy was carried out for histology and blood biochemical tests: total bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase. The animals were euthanized under anesthesia. This research was approved by the Ethics Committee on Animal Use (CEUA, Unicamp, No. 2511-1). In the CCG, 100% of the animals showed bile duct dilatation, ductular proliferation, and portal inflammatory infiltrate; 60% showed regenerative nodule formation; and 80% had porta-porta septa and foci of necrosis, all of which were not found in the OSG. All CCG group biochemical tests had significant increases (P Wistar rats caused hepatic dysfunction and biochemical and histological injuries with degrees of distortion to the hepatic architecture. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. The 100 kV Faraday cage (High Voltage Deck) for the SPIDER experiment

    International Nuclear Information System (INIS)

    Boldrin, Marco; Grando, Luca; Pesce, Alberto; Recchia, Mauro; Toigo, Vanni; Gutierrez, Daniel; Simon, Muriel; Faoro, Giovanni; Guion, Andrea; Maggiora, Edoardo; Pedron, Diego; Roman, Anita; Decamps, Hans

    2015-01-01

    Highlights: • A 100 keV experiment is under construction to optimize ITER NBI Ion Source. • The Ion Source Power Supplies are hosted inside a wide −100 kVdc Faraday cage (HVD). • The paper reports on the design solutions of the HVD. • Electrostatic and electromagnetic analyses are presented. • Procurement activities status is reported. - Abstract: In order to optimize the design and operation of the Ion Source for the ITER Neutral Beam Injector (NBI), a dedicated 100 keV Ion Source, identified as Source for the Production of Ions of Deuterium Extracted from RF plasma (SPIDER), is under construction in the Neutral Beam Test Facility, at the Consorzio RFX premises, in Padua, Italy. The Ion Source, polarized at −112 kVdc voltage, will produce negative ions (Deuterium D"− or Hydrogen H"−) which, extracted from the Plasma Grid with an extraction voltage up to 12 keV, are accelerated up to 100 keV by the 100 kVdc Power Supply (100 kV PS). The required Ion Source and the Extraction Power Supplies (ISEPS) system and the associated diagnostics are hosted inside a High Voltage Deck (HVD), a −100 kVdc air-insulated Faraday cage. These power supplies and various diagnostics and control equipment are connected to the Ion Source by means of a High Voltage Transmission Line (TL). The HVD (procurement started mid 2013; delivery on site in the second half of 2014) will consist of a wide structure (13 m (L) × 11 m (W) × 5 m (H)), designed to support the weight of the ISEPS components, mounted on supporting insulators and clad with a conductive metal sheet in order to reduce the electromagnetic interference (EMI). The paper reports on the design solutions of the HVD focusing on insulation, mechanical, thermal and EMI issues. The details of the main HVD interfaces with the TL and with insulating transformer are also described. Finite Element (FE) analyses have been performed, on the one hand, to verify the configuration from the electrostatic point of view and

  18. The 100 kV Faraday cage (High Voltage Deck) for the SPIDER experiment

    Energy Technology Data Exchange (ETDEWEB)

    Boldrin, Marco, E-mail: marco.boldrin@igi.cnr.it [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete S.p.A.), Corso Stati Uniti 4, 35127 Padova (Italy); Grando, Luca; Pesce, Alberto; Recchia, Mauro; Toigo, Vanni [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete S.p.A.), Corso Stati Uniti 4, 35127 Padova (Italy); Gutierrez, Daniel; Simon, Muriel [Fusion for Energy, c/o Josep Pla 2, 08019 Barcelona (Spain); Faoro, Giovanni; Guion, Andrea; Maggiora, Edoardo; Pedron, Diego [COELME – Costruzioni Elettromeccaniche S.p.A., via G. Galilei no. 1/2, 30036 S. Maria di Sala, Venezia (Italy); Roman, Anita [Studio di Ingegneria RS s.r.l., Viale dell’Arcella 1, 35153 Padova (Italy); Decamps, Hans [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

    2015-10-15

    Highlights: • A 100 keV experiment is under construction to optimize ITER NBI Ion Source. • The Ion Source Power Supplies are hosted inside a wide −100 kVdc Faraday cage (HVD). • The paper reports on the design solutions of the HVD. • Electrostatic and electromagnetic analyses are presented. • Procurement activities status is reported. - Abstract: In order to optimize the design and operation of the Ion Source for the ITER Neutral Beam Injector (NBI), a dedicated 100 keV Ion Source, identified as Source for the Production of Ions of Deuterium Extracted from RF plasma (SPIDER), is under construction in the Neutral Beam Test Facility, at the Consorzio RFX premises, in Padua, Italy. The Ion Source, polarized at −112 kVdc voltage, will produce negative ions (Deuterium D{sup −} or Hydrogen H{sup −}) which, extracted from the Plasma Grid with an extraction voltage up to 12 keV, are accelerated up to 100 keV by the 100 kVdc Power Supply (100 kV PS). The required Ion Source and the Extraction Power Supplies (ISEPS) system and the associated diagnostics are hosted inside a High Voltage Deck (HVD), a −100 kVdc air-insulated Faraday cage. These power supplies and various diagnostics and control equipment are connected to the Ion Source by means of a High Voltage Transmission Line (TL). The HVD (procurement started mid 2013; delivery on site in the second half of 2014) will consist of a wide structure (13 m (L) × 11 m (W) × 5 m (H)), designed to support the weight of the ISEPS components, mounted on supporting insulators and clad with a conductive metal sheet in order to reduce the electromagnetic interference (EMI). The paper reports on the design solutions of the HVD focusing on insulation, mechanical, thermal and EMI issues. The details of the main HVD interfaces with the TL and with insulating transformer are also described. Finite Element (FE) analyses have been performed, on the one hand, to verify the configuration from the electrostatic point of

  19. Coupling between the voltage-sensing and pore domains in a voltage-gated potassium channel.

    Science.gov (United States)

    Schow, Eric V; Freites, J Alfredo; Nizkorodov, Alex; White, Stephen H; Tobias, Douglas J

    2012-07-01

    Voltage-dependent potassium (Kv), sodium (Nav), and calcium channels open and close in response to changes in transmembrane (TM) potential, thus regulating cell excitability by controlling ion flow across the membrane. An outstanding question concerning voltage gating is how voltage-induced conformational changes of the channel voltage-sensing domains (VSDs) are coupled through the S4-S5 interfacial linking helices to the opening and closing of the pore domain (PD). To investigate the coupling between the VSDs and the PD, we generated a closed Kv channel configuration from Aeropyrum pernix (KvAP) using atomistic simulations with experiment-based restraints on the VSDs. Full closure of the channel required, in addition to the experimentally determined TM displacement, that the VSDs be displaced both inwardly and laterally around the PD. This twisting motion generates a tight hydrophobic interface between the S4-S5 linkers and the C-terminal ends of the pore domain S6 helices in agreement with available experimental evidence.

  20. High-voltage picoamperemeter

    Energy Technology Data Exchange (ETDEWEB)

    Bugl, Andrea; Ball, Markus; Boehmer, Michael; Doerheim, Sverre; Hoenle, Andreas; Konorov, Igor [Technische Universitaet Muenchen, Garching (Germany); Ketzer, Bernhard [Technische Universitaet Muenchen, Garching (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany)

    2014-07-01

    Current measurements in the nano- and picoampere region on high voltage are an important tool to understand charge transfer processes in micropattern gas detectors like the Gas Electron Multiplier (GEM). They are currently used to e.g. optimize the field configuration in a multi-GEM stack to be used in the ALICE TPC after the upgrade of the experiment during the 2nd long shutdown of the LHC. Devices which allow measurements down to 1pA at high voltage up to 6 kV have been developed at TU Muenchen. They are based on analog current measurements via the voltage drop over a switchable shunt. A microcontroller collects 128 digital ADC values and calculates their mean and standard deviation. This information is sent with a wireless transmitting unit to a computer and stored in a root file. A nearly unlimited number of devices can be operated simultaneously and read out by a single receiver. The results can also be displayed on a LCD directly at the device. Battery operation and the wireless readout are important to protect the user from any contact to high voltage. The principle of the device is explained, and systematic studies of their properties are shown.

  1. [Time of cord clamping and neonatal complications, a prospective study].

    Science.gov (United States)

    Rincón, D; Foguet, A; Rojas, M; Segarra, E; Sacristán, E; Teixidor, R; Ortega, A

    2014-09-01

    To assess the effects of early or late clamping of the umbilical cord in term newborns, assessing the levels of hemoglobin, hematocrit, and ferritin, and their correlation with some of the complications. A prospective study of healthy newborns at term or born by dystotic or eutocic delivery in our hospital between May 2009 until May 2010. Patients were assigned according to the time of clamping, group 1 (<60 seconds), group 2 (1 to<2 minutes), and group 3 (2 to 3 minutes). Laboratory tests were performed at birth and at 48 hours of life, assessing the levels of hemoglobin, hematocrit, ferritin, and bilirubin. The risk of polycythemia, respiratory distress syndrome, neonatal phototherapy or admission to the Intensive Care Unit and the hospital stay, were evaluated. A total of 242 patients were included: group 1 (g1=80), group 2 (g2=31) y group 3 (g3=131). The background maternal and neonatal characteristics were similar in all sets. The first test showed significant differences in ferritin levels in those infants with delayed clamping (g1: 111 mg/dl, g2: 125 mg/dl, g3: 173 mg/dl; p<0.01). In the second analysis the values of hemoglobin (g1: 17.3 g/dl, g2: 18.9 g/dl, g3: 19.2 g/dl; p<0.01), hematocrit (g1: 53.4%, g2: 58%, g3: 59%; p<0.01) and ferritin (g1: 254 mg/dl, g2: 254.7 mg/dl, g3: 313 mg/dl; p = 0.008) were statistically higher in this group. As regards complications, a significant increase was observed in the number of cases of polycythemia symptoms in group 3. The late cord clamping is associated with an increase in hematocrit, hemoglobin and ferritin at 48 hours of life, as well as an increased risk of polycythemia present with symptoms. Copyright © 2013 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.

  2. Mitigation of Unbalanced Voltage Sags and Voltage Unbalance in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system...... to unbalanced faults. The compensation of unbalanced voltage sags and voltage unbalance in the CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0........ The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and net-works like this. The voltage unbalances, for the tested cases in the CIGRE LV test network are mainly due to single phase loads and due...

  3. Localized accumulation of cytosolic calcium near the fused sperm is associated with the calcium- and voltage-dependent block of sperm entry in the sea urchin egg.

    Science.gov (United States)

    Ivonnet, Pedro I; Mohri, Tatsuma; McCulloh, David H

    2017-10-01

    Interaction of the sperm and egg depolarizes the egg membrane, allowing the sperm to enter; however, if the egg membrane is not allowed to depolarize from its resting potential (e.g., by voltage-clamp), the sperm will not enter. Previous studies demonstrated that sperm entry into sea urchin eggs that are voltage-clamped at negative membrane potentials is regulated both by the egg's membrane potential and a voltage-dependent influx of calcium into the egg. In these cases, electrical or cytoplasmic continuity (sperm-egg membrane fusion) occurs at negative membrane potentials, but subsequent loss of cytoplasmic continuity results in failure of sperm entry (unfusion). The work presented herein examined where, in relation to the sperm, and when, in relation to the sperm-induced electrophysiological events, the egg's calcium influx occurs, and how these events relate to successful or failed sperm entry. When sperm entered the egg, elevation of intracellular calcium concentration ([Ca 2+ ] i ) began near the fused sperm on average 5.9 s after sperm-egg membrane fusion. Conversely, when sperm failed to enter the egg, [Ca 2+ ] i elevated near the site of sperm-egg fusion on average 0.7 s after sperm-egg membrane fusion, which is significantly earlier than in eggs for which sperm entered. Therefore, the accumulation of calcium near the site of sperm-egg fusion is spatially and temporally consistent with the mechanism that may be responsible for loss of cytoplasmic continuity and failure of sperm entry. © 2017 Wiley Periodicals, Inc.

  4. Direct Effect of Remifentanil and Glycine Contained in Ultiva® on Nociceptive Transmission in the Spinal Cord: In Vivo and Slice Patch Clamp Analyses.

    Directory of Open Access Journals (Sweden)

    Makoto Sumie

    Full Text Available Ultiva® is commonly administered intravenously for analgesia during general anaesthesia and its main constituent remifentanil is an ultra-short-acting μ-opioid receptor agonist. Ultiva® is not approved for epidural or intrathecal use in clinical practice. Previous studies have reported that Ultiva® provokes opioid-induced hyperalgesia by interacting with spinal dorsal horn neurons. Ultiva® contains glycine, an inhibitory neurotransmitter but also an N-methyl-D-aspartate receptor co-activator. The presence of glycine in the formulation of Ultiva® potentially complicates its effects. We examined how Ultiva® directly affects nociceptive transmission in the spinal cord.We made patch-clamp recordings from substantia gelatinosa (SG neurons in the adult rat spinal dorsal horn in vivo and in spinal cord slices. We perfused Ultiva® onto the SG neurons and analysed its effects on the membrane potentials and synaptic responses activated by noxious mechanical stimuli.Bath application of Ultiva® hyperpolarized membrane potentials under current-clamp conditions and produced an outward current under voltage-clamp conditions. A barrage of excitatory postsynaptic currents (EPSCs evoked by the stimuli was suppressed by Ultiva®. Miniature EPSCs (mEPSCs were depressed in frequency but not amplitude. Ultiva®-induced outward currents and suppression of mEPSCs were not inhibited by the μ-opioid receptor antagonist naloxone, but were inhibited by the glycine receptor antagonist strychnine. The Ultiva®-induced currents demonstrated a specific equilibrium potential similar to glycine.We found that intrathecal administration of Ultiva® to SG neurons hyperpolarized membrane potentials and depressed presynaptic glutamate release predominantly through the activation of glycine receptors. No Ultiva®-induced excitatory effects were observed in SG neurons. Our results suggest different analgesic mechanisms of Ultiva® between intrathecal and intravenous

  5. Modeling error and apparent isotope discrimination confound estimation of endogenous glucose production during euglycemic glucose clamps

    International Nuclear Information System (INIS)

    Finegood, D.T.; Bergman, R.N.; Vranic, M.

    1988-01-01

    We previously demonstrated that conventional tracer methods applied to euglycemic-hyperinsulinemic glucose clamps result in substantially negative estimates for the rate of endogenous glucose production, particularly during the first half of 180-min clamps. We also showed that addition of tracer to the exogenous glucose infusate resulted in nonnegative endogenous glucose production (Ra) estimates. In this study, we investigated the underlying cause of negative estimates of Ra from conventional clamp/tracer methods and the reason for the difference in estimates when tracer is added to the exogenous glucose infusate. We performed euglycemic-hyperinsulinemic (300-microU/ml) clamps in normal dogs without (cold GINF protocol, n = 6) or with (hot GINF protocol, n = 6) tracer (D-[3-3H]glucose) added to the exogenous glucose infusate. In the hot GINF protocol, sufficient tracer was added to the exogenous glucose infusate such that arterial plasma specific activity (SAa) did not change from basal through the clamp period (P greater than .05). In the cold GINF studies, plasma SAa fell 81 +/- 2% from the basal level by the 3rd h of clamping. We observed a significant, transient, positive venous-arterial difference in specific activity (SAv-SAa difference) during the cold GINF studies. The SAv-SAa difference reached a peak of 27 +/- 6% at 30 min and diminished to a plateau of 7 +/- 1% between 70 and 180 min. We also observed a positive but constant SAv-SAa difference (4.6 +/- 0.2% between 10 and 180 min) during the hot GINF studies

  6. Heparin/heparan sulfates bind to and modulate neuronal L-type (Cav1.2) voltage-dependent Ca2+ channels

    DEFF Research Database (Denmark)

    Garau, Gianpiero; Magotti, Paola; Heine, Martin

    2015-01-01

    Our previous studies revealed that L-type voltage-dependent Ca2+ channels (Cav1.2 L-VDCCs) are modulated by the neural extracellular matrix backbone, polyanionic glycan hyaluronic acid. Here we used isothermal titration calorimetry and screened a set of peptides derived from the extracellular......M), integrating their enthalpic and entropic binding contributions. Interaction between heparin and recombinant as well as native full-length neuronal Cav1.2α1 channels was confirmed using the heparin–agarose pull down assay. Whole cell patch clamp recordings in HEK293 cells transfected with neuronal Cav1.......2 channels revealed that enzymatic digestion of highly sulfated heparan sulfates with heparinase 1 affects neither voltage-dependence of channel activation nor the level of steady state inactivation, but did speed up channel inactivation. Treatment of hippocampal cultures with heparinase 1 reduced the firing...

  7. KCNQ1 channel modulation by KCNE proteins via the voltage-sensing domain.

    Science.gov (United States)

    Nakajo, Koichi; Kubo, Yoshihiro

    2015-06-15

    The gating of the KCNQ1 potassium channel is drastically regulated by auxiliary subunit KCNE proteins. KCNE1, for example, slows the activation kinetics of KCNQ1 by two orders of magnitude. Like other voltage-gated ion channels, the opening of KCNQ1 is regulated by the voltage-sensing domain (VSD; S1-S4 segments). Although it has been known that KCNE proteins interact with KCNQ1 via the pore domain, some recent reports suggest that the VSD movement may be altered by KCNE. The altered VSD movement of KCNQ1 by KCNE proteins has been examined by site-directed mutagenesis, the scanning cysteine accessibility method (SCAM), voltage clamp fluorometry (VCF) and gating charge measurements. These accumulated data support the idea that KCNE proteins interact with the VSDs of KCNQ1 and modulate the gating of the KCNQ1 channel. In this review, we will summarize recent findings and current views of the KCNQ1 modulation by KCNE via the VSD. In this context, we discuss our recent findings that KCNE1 may alter physical interactions between the S4 segment (VSD) and the S5 segment (pore domain) of KCNQ1. Based on these findings from ourselves and others, we propose a hypothetical mechanism for how KCNE1 binding alters the VSD movement and the gating of the channel. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  8. Computational optogenetics: empirically-derived voltage- and light-sensitive channelrhodopsin-2 model.

    Directory of Open Access Journals (Sweden)

    John C Williams

    Full Text Available Channelrhodospin-2 (ChR2, a light-sensitive ion channel, and its variants have emerged as new excitatory optogenetic tools not only in neuroscience, but also in other areas, including cardiac electrophysiology. An accurate quantitative model of ChR2 is necessary for in silico prediction of the response to optical stimulation in realistic tissue/organ settings. Such a model can guide the rational design of new ion channel functionality tailored to different cell types/tissues. Focusing on one of the most widely used ChR2 mutants (H134R with enhanced current, we collected a comprehensive experimental data set of the response of this ion channel to different irradiances and voltages, and used these data to develop a model of ChR2 with empirically-derived voltage- and irradiance- dependence, where parameters were fine-tuned via simulated annealing optimization. This ChR2 model offers: 1 accurate inward rectification in the current-voltage response across irradiances; 2 empirically-derived voltage- and light-dependent kinetics (activation, deactivation and recovery from inactivation; and 3 accurate amplitude and morphology of the response across voltage and irradiance settings. Temperature-scaling factors (Q10 were derived and model kinetics was adjusted to physiological temperatures. Using optical action potential clamp, we experimentally validated model-predicted ChR2 behavior in guinea pig ventricular myocytes. The model was then incorporated in a variety of cardiac myocytes, including human ventricular, atrial and Purkinje cell models. We demonstrate the ability of ChR2 to trigger action potentials in human cardiomyocytes at relatively low light levels, as well as the differential response of these cells to light, with the Purkinje cells being most easily excitable and ventricular cells requiring the highest irradiance at all pulse durations. This new experimentally-validated ChR2 model will facilitate virtual experimentation in neural and

  9. Safety of minimally invasive mitral valve surgery without aortic cross-clamp.

    Science.gov (United States)

    Umakanthan, Ramanan; Leacche, Marzia; Petracek, Michael R; Kumar, Sathappan; Solenkova, Nataliya V; Kaiser, Clayton A; Greelish, James P; Balaguer, Jorge M; Ahmad, Rashid M; Ball, Stephen K; Hoff, Steven J; Absi, Tarek S; Kim, Betty S; Byrne, John G

    2008-05-01

    We developed a technique for open heart surgery through a small (5 cm) right-anterolateral thoracotomy without aortic cross-clamp. One hundred and ninety-five consecutive patients (103 male and 92 female), age 69 +/- 8 years, underwent surgery between January 2006 and July 2007. Mean preoperative New York Heart Association function class was 2.2 +/- 0.7. Thirty-five patients (18%) had an ejection fraction 0.35 or less. Cardiopulmonary bypass was instituted through femoral (176 of 195, 90%), axillary (18 of 195, 9%), or direct aortic (1 of 195, 0.5%) cannulation. Under cold fibrillatory arrest (mean temperature 28.2 degrees C) without aortic cross-clamp, mitral valve repair (72 of 195, 37%), mitral valve replacement (117 of 195, 60%), or other (6 of 195, 3%) procedures were performed. Concomitant procedures included maze (45 of 195, 23%), patent foramen ovale closure (42 of 195, 22%) and tricuspid valve repair (16 of 195, 8%), or replacement (4 of 195, 2%). Thirty-day mortality was 3% (6 of 195). Duration of fibrillatory arrest, cardiopulmonary bypass, and "skin to skin" surgery were 88 +/- 32, 118 +/- 52, and 280 +/- 78 minutes, respectively. Ten patients (5%) underwent reexploration for bleeding and 44% did not receive any blood transfusions. Six patients (3%) sustained a postoperative stroke, eight (4%) developed low cardiac output syndrome, and two (1%) developed renal failure requiring hemodialysis. Mean length of hospital stay was 7 +/- 4.8 days. This simplified technique of minimally invasive open heart surgery is safe and easily reproducible. Fibrillatory arrest without aortic cross-clamping, with coronary perfusion against an intact aortic valve, does not increase the risk of stroke or low cardiac output. It may be particularly useful in higher risk patients in whom sternotomy with aortic clamping is less desirable.

  10. Depression of voltage-activated Ca2+ release in skeletal muscle by activation of a voltage-sensing phosphatase.

    Science.gov (United States)

    Berthier, Christine; Kutchukian, Candice; Bouvard, Clément; Okamura, Yasushi; Jacquemond, Vincent

    2015-04-01

    Phosphoinositides act as signaling molecules in numerous cellular transduction processes, and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) regulates the function of several types of plasma membrane ion channels. We investigated the potential role of PtdIns(4,5)P2 in Ca(2+) homeostasis and excitation-contraction (E-C) coupling of mouse muscle fibers using in vivo expression of the voltage-sensing phosphatases (VSPs) Ciona intestinalis VSP (Ci-VSP) or Danio rerio VSP (Dr-VSP). Confocal images of enhanced green fluorescent protein-tagged Dr-VSP revealed a banded pattern consistent with VSP localization within the transverse tubule membrane. Rhod-2 Ca(2+) transients generated by 0.5-s-long voltage-clamp depolarizing pulses sufficient to elicit Ca(2+) release from the sarcoplasmic reticulum (SR) but below the range at which VSPs are activated were unaffected by the presence of the VSPs. However, in Ci-VSP-expressing fibers challenged by 5-s-long depolarizing pulses, the Ca(2+) level late in the pulse (3 s after initiation) was significantly lower at 120 mV than at 20 mV. Furthermore, Ci-VSP-expressing fibers showed a reversible depression of Ca(2+) release during trains, with the peak Ca(2+) transient being reduced by ∼30% after the application of 10 200-ms-long pulses to 100 mV. A similar depression was observed in Dr-VSP-expressing fibers. Cav1.1 Ca(2+) channel-mediated current was unaffected by Ci-VSP activation. In fibers expressing Ci-VSP and a pleckstrin homology domain fused with monomeric red fluorescent protein (PLCδ1PH-mRFP), depolarizing pulses elicited transient changes in mRFP fluorescence consistent with release of transverse tubule-bound PLCδ1PH domain into the cytosol; the voltage sensitivity of these changes was consistent with that of Ci-VSP activation, and recovery occurred with a time constant in the 10-s range. Our results indicate that the PtdIns(4,5)P2 level is tightly maintained in the transverse tubule membrane of the muscle fibers

  11. Axially Modulated Clamped-Guided Arch Resonator for Memory and Logic Applications

    KAUST Repository

    Hafiz, Md Abdullah Al; Tella, Sherif Adekunle; Alcheikh, Nouha; Fariborzi, Hossein; Younis, Mohammad I.

    2017-01-01

    We experimentally demonstrate memory and logic devices based on an axially modulated clamped-guided arch resonator. The device are electrostatically actuated and capacitively sensed, while the resonance frequency modulation is achieved through an axial electrostatic force from the guided side of the clamped-guided arch microbeam. We present two case studies: first, a dynamic memory based on the nonlinear frequency response of the resonator, and second, a reprogrammable two-input logic gate based on the linear frequency modulation of the resonator. These devices show energy cost per memory/logic operation in pJ, are fully compatible with CMOS fabrication processes, have the potential for on-chip system integration, and operate at room temperature.

  12. Axially Modulated Clamped-Guided Arch Resonator for Memory and Logic Applications

    KAUST Repository

    Hafiz, Md Abdullah Al

    2017-11-03

    We experimentally demonstrate memory and logic devices based on an axially modulated clamped-guided arch resonator. The device are electrostatically actuated and capacitively sensed, while the resonance frequency modulation is achieved through an axial electrostatic force from the guided side of the clamped-guided arch microbeam. We present two case studies: first, a dynamic memory based on the nonlinear frequency response of the resonator, and second, a reprogrammable two-input logic gate based on the linear frequency modulation of the resonator. These devices show energy cost per memory/logic operation in pJ, are fully compatible with CMOS fabrication processes, have the potential for on-chip system integration, and operate at room temperature.

  13. Integral transform solution of bending problem of clamped orthotropic rectangular plates

    International Nuclear Information System (INIS)

    An, C.; Gu, J.-J.; Su, J.

    2011-01-01

    The generalized integral transform technique (GITT) is employed to obtain an exact solution for the bending problem of fully clamped orthotropic rectangular plates. The use of the GITT approach in the analysis of the transverse deflection equation leads to a coupled system of fourth order differential equations in the dimensionless longitudinal spatial variable. The resulting transformed ODE system is then numerically solved by making use of the subroutine DBVPFD from IMSL Library. Numerical results with automatic global accuracy control are produced for different values of aspect ratio. Critical comparisons with previously reported numerical results are performed with excellent agreement. Several sets of reference results for clamped orthotropic rectangular plates are also provided for future covalidation purposes. (author)

  14. Direct model-based predictive control scheme without cost function for voltage source inverters with reduced common-mode voltage

    Science.gov (United States)

    Kim, Jae-Chang; Moon, Sung-Ki; Kwak, Sangshin

    2018-04-01

    This paper presents a direct model-based predictive control scheme for voltage source inverters (VSIs) with reduced common-mode voltages (CMVs). The developed method directly finds optimal vectors without using repetitive calculation of a cost function. To adjust output currents with the CMVs in the range of -Vdc/6 to +Vdc/6, the developed method uses voltage vectors, as finite control resources, excluding zero voltage vectors which produce the CMVs in the VSI within ±Vdc/2. In a model-based predictive control (MPC), not using zero voltage vectors increases the output current ripples and the current errors. To alleviate these problems, the developed method uses two non-zero voltage vectors in one sampling step. In addition, the voltage vectors scheduled to be used are directly selected at every sampling step once the developed method calculates the future reference voltage vector, saving the efforts of repeatedly calculating the cost function. And the two non-zero voltage vectors are optimally allocated to make the output current approach the reference current as close as possible. Thus, low CMV, rapid current-following capability and sufficient output current ripple performance are attained by the developed method. The results of a simulation and an experiment verify the effectiveness of the developed method.

  15. High-voltage CMOS detectors

    International Nuclear Information System (INIS)

    Ehrler, F.; Blanco, R.; Leys, R.; Perić, I.

    2016-01-01

    High-voltage CMOS (HVCMOS) pixel sensors are depleted active pixel sensors implemented in standard commercial CMOS processes. The sensor element is the n-well/p-substrate diode. The sensor electronics are entirely placed inside the n-well which is at the same time used as the charge collection electrode. High voltage is used to deplete the part of the substrate around the n-well. HVCMOS sensors allow implementation of complex in-pixel electronics. This, together with fast signal collection, allows a good time resolution, which is required for particle tracking in high energy physics. HVCMOS sensors will be used in Mu3e experiment at PSI and are considered as an option for both ATLAS and CLIC (CERN). Radiation tolerance and time walk compensation have been tested and results are presented. - Highlights: • High-voltage CMOS sensors will be used in Mu3e experiment at PSI (Switzerland). • HVCMOS sensors are considered as an option for ATLAS (LHC/CERN) and CLIC (CERN). • Efficiency of more than 95% (99%) has been measured with (un-)irradiated chips. • The time resolution measured in the beam tests is nearly 100 ns. • We plan to improve time resolution and efficiency by using high-resistive substrate.

  16. High-voltage CMOS detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ehrler, F., E-mail: felix.ehrler@student.kit.edu; Blanco, R.; Leys, R.; Perić, I.

    2016-07-11

    High-voltage CMOS (HVCMOS) pixel sensors are depleted active pixel sensors implemented in standard commercial CMOS processes. The sensor element is the n-well/p-substrate diode. The sensor electronics are entirely placed inside the n-well which is at the same time used as the charge collection electrode. High voltage is used to deplete the part of the substrate around the n-well. HVCMOS sensors allow implementation of complex in-pixel electronics. This, together with fast signal collection, allows a good time resolution, which is required for particle tracking in high energy physics. HVCMOS sensors will be used in Mu3e experiment at PSI and are considered as an option for both ATLAS and CLIC (CERN). Radiation tolerance and time walk compensation have been tested and results are presented. - Highlights: • High-voltage CMOS sensors will be used in Mu3e experiment at PSI (Switzerland). • HVCMOS sensors are considered as an option for ATLAS (LHC/CERN) and CLIC (CERN). • Efficiency of more than 95% (99%) has been measured with (un-)irradiated chips. • The time resolution measured in the beam tests is nearly 100 ns. • We plan to improve time resolution and efficiency by using high-resistive substrate.

  17. Gambierol, a toxin produced by the dinoflagellate Gambierdiscus toxicus, is a potent blocker of voltage-gated potassium channels☆

    Science.gov (United States)

    Cuypers, Eva; Abdel-Mottaleb, Yousra; Kopljar, Ivan; Rainier, Jon D.; Raes, Adam L.; Snyders, Dirk J.; Tytgat, Jan

    2008-01-01

    In this study, we pharmacologically characterized gambierol, a marine polycyclic ether toxin which is produced by the dinoflagellate Gambierdiscus toxicus. Besides several other polycyclic ether toxins like ciguatoxins, this scarcely studied toxin is one of the compounds that may be responsible for ciguatera fish poisoning (CFP). Unfortunately, the biological target(s) that underlies CFP is still partly unknown. Today, ciguatoxins are described to specifically activate voltage-gated sodium channels by interacting with their receptor site 5. But some dispute about the role of gambierol in the CFP story shows up: some describe voltage-gated sodium channels as the target, while others pinpoint voltage-gated potassium channels as targets. Since gambierol was never tested on isolated ion channels before, it was subjected in this work to extensive screening on a panel of 17 ion channels: nine cloned voltage-gated ion channels (mammalian Nav1.1–Nav1.8 and insect Para) and eight cloned voltage-gated potassium channels (mammalian Kv1.1–Kv1.6, hERG and insect ShakerIR) expressed in Xenopus laevis oocytes using two-electrode voltage-clamp technique. All tested sodium channel subtypes are insensitive to gambierol concentrations up to 10 μM. In contrast, Kv1.2 is the most sensitive voltage-gated potassium channel subtype with almost full block (>97%) and an half maximal inhibitory concentration (IC50) of 34.5 nM. To the best of our knowledge, this is the first study where the selectivity of gambierol is tested on isolated voltage-gated ion channels. Therefore, these results lead to a better understanding of gambierol and its possible role in CFP and they may also be useful in the development of more effective treatments. PMID:18313714

  18. Visibility of changes in light intensity caused by voltage leaps

    International Nuclear Information System (INIS)

    Seljeseth, Helge; Mogstad, Olve

    2006-05-01

    Sintef Energy Research was engaged by NVE to evaluate the official requirements on voltage leaps in regulations concerning quality of delivery, and simultaneously conduct tests with a panel of test persons in order to get more detailed evaluations and recommendations to the existing requirements on voltage leaps. Tests and laboratory experiments have been performed on a total of 96 test persons, and the results reveal that voltage leaps even smaller than the 3 percent limit set by Norwegian regulations are visible to most people. The majority of the test persons consider the light conditions as unacceptably bad when light conditions are near the limit of voltage leap. Moreover, 25 percent of the test persons considered the light quality unacceptable when the voltage leap was well under half of the official limit.The results of the experiments indicates a need for narrowing the restrictions on voltage leaps in the Norwegian power network in order to limit the size and frequency of this kind of disturbance in the voltage. Recommendations for regulations are elaborated in chapter 3 (ml)

  19. Automated patch clamp on mESC-derived cardiomyocytes for cardiotoxicity prediction.

    Science.gov (United States)

    Stoelzle, Sonja; Haythornthwaite, Alison; Kettenhofen, Ralf; Kolossov, Eugen; Bohlen, Heribert; George, Michael; Brüggemann, Andrea; Fertig, Niels

    2011-09-01

    Cardiovascular side effects are critical in drug development and have frequently led to late-stage project terminations or even drug withdrawal from the market. Physiologically relevant and predictive assays for cardiotoxicity are hence strongly demanded by the pharmaceutical industry. To identify a potential impact of test compounds on ventricular repolarization, typically a variety of ion channels in diverse heterologously expressing cells have to be investigated. Similar to primary cells, in vitro-generated stem cell-derived cardiomyocytes simultaneously express cardiac ion channels. Thus, they more accurately represent the native situation compared with cell lines overexpressing only a single type of ion channel. The aim of this study was to determine if stem cell-derived cardiomyocytes are suited for use in an automated patch clamp system. The authors show recordings of cardiac ion currents as well as action potential recordings in readily available stem cell-derived cardiomyocytes. Besides monitoring inhibitory effects of reference compounds on typical cardiac ion currents, the authors revealed for the first time drug-induced modulation of cardiac action potentials in an automated patch clamp system. The combination of an in vitro cardiac cell model with higher throughput patch clamp screening technology allows for a cost-effective cardiotoxicity prediction in a physiologically relevant cell system.

  20. Non-isolated DC-AC converter with high voltage gain for autonomous systems of electric power; Conversor CC-CA nao isolado com alto ganho de tensao para aplicacao em sistemas autonomos de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, George Cajazeiras [Centro Federal de Educacao Tecnologica do Ceara (CEFET/CE), Fortaleza, CE (Brazil); Torrico-Bascope, Rene P. [Universidade Federal do Ceara (PPGEE/UFC), Fortaleza, CE (Brazil). Programa de Pos Graduacao em Engenharia Eletrica; Borges Neto, Manuel Rangel [Centro Federal de Educacao Tecnologica de Petrolina (CEFET-PET), PE (Brazil)

    2008-07-01

    A non-isolated DC-AC converter with high voltage gain with two output sinusoidal voltage - 110 V and 220 V - and frequency 60 Hz for application in autonomous systems of electric power is proposed in this work. This topology consists of a boost converter with high voltage gain, based on three-state switching cell combined with a double half bridge inverter. This configuration type the size and the cost are reduced and the efficiency is gotten better, due to the reduced number of switches. The converters that compose this topology operate with high frequency, reducing the volume of the magnetic materials. can be mention as important characteristics: the voltage stress across the switches of the boost converter are low, due they be naturally clamped by one output filter capacitor, which allows the utilization of switches with lower conduction resistances, and the waveforms of the output voltage of the double half bridge inverter supplies for the load it is sinusoidal and it possesses low harmonic content. (author)

  1. Design, construction and tests of the power crowbar and predischarge circuit of the SPICA II experiment

    International Nuclear Information System (INIS)

    Ingen, A.M. van; Manintveld, P.; Sterk, A.B.

    1983-01-01

    A 28 Farad, 1.8 MJ electrolytic capacitor power-crowbar battery and a flexible predischarge circuit for the SPICA II screw-pinch experiment is described. The battery is capable of delivering the toroidal and poloidal currents of more than 2.5 MA, during at least 1 ms after crowbarring of the high-voltage capacitor banks. To obtain a low short-circuit impedance a very compact construction was chosen, which resulted in seven modules of about 1 m 3 each, Rsub(i) = 100 μΩ, Lsub(i) = 7 nH, connected by plate systems to the main circuit. The predischarge circuit consists of a fast capacitor bank to start the predischarge and a slow circuit with a clamp switch to preheat the discharge. (author)

  2. Voltage breakdown on niobium and copper surfaces

    International Nuclear Information System (INIS)

    Werner, G.R.; Padamsee, H.; Betzwieser, J.C.; Liu, Y.G.; Rubin, K.H.R.; Shipman, J.E.; Ying, L.T.

    2003-01-01

    Experiments have shown that voltage breakdown in superconducting niobium RF cavities is in many ways similar to voltage breakdown on niobium cathodes in DC voltage gaps; most striking are the distinctive starburst patterns and craters that mark the site of voltage breakdown in both superconducting cavities and DC vacuum gaps. Therefore, we can learn much about RF breakdown from simpler, faster DC experiments. We have direct evidence, in the form of before'' and ''after'' pictures, that breakdown events caused by high surface electric fields occur with high probability at contaminant particles on surfaces. Although the pre-breakdown behavior (field emission) seems to depend mostly on the contaminant particles present and little on the substrate, the breakdown event itself is greatly affected by the substrate-niobium, heavily oxidized niobium, electropolished copper, and diamond-machined copper cathodes lead to different kinds of breakdown events. By studying DC voltage breakdown we hope to learn more details about the processes involved in the transition from field emission to catastrophic arcing and the cratering of the surface; as well as learning how to prevent breakdown, we would like to learn how to cause breakdown, which could be important when ''processing'' cavities to reduce field emission. (author)

  3. Nonlinear electrokinetics at large voltages

    Energy Technology Data Exchange (ETDEWEB)

    Bazant, Martin Z [Department of Chemical Engineering and Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Sabri Kilic, Mustafa; Ajdari, Armand [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Storey, Brian D [Franklin W Olin College of Engineering, Needham, MA 02492 (United States)], E-mail: bazant@mit.edu

    2009-07-15

    The classical theory of electrokinetic phenomena assumes a dilute solution of point-like ions in chemical equilibrium with a surface whose double-layer voltage is of order the thermal voltage, k{sub B}T/e=25 mV. In nonlinear 'induced-charge' electrokinetic phenomena, such as ac electro-osmosis, several volts {approx}100k{sub B}T/e are applied to the double layer, and the theory breaks down and cannot explain many observed features. We argue that, under such a large voltage, counterions 'condense' near the surface, even for dilute bulk solutions. Based on simple models, we predict that the double-layer capacitance decreases and the electro-osmotic mobility saturates at large voltages, due to steric repulsion and increased viscosity of the condensed layer, respectively. The former suffices to explain observed high-frequency flow reversal in ac electro-osmosis; the latter leads to a salt concentration dependence of induced-charge flows comparable to experiments, although a complete theory is still lacking.

  4. S1 constrains S4 in the voltage sensor domain of Kv7.1 K+ channels.

    Directory of Open Access Journals (Sweden)

    Yoni Haitin

    Full Text Available Voltage-gated K(+ channels comprise a central pore enclosed by four voltage-sensing domains (VSDs. While movement of the S4 helix is known to couple to channel gate opening and closing, the nature of S4 motion is unclear. Here, we substituted S4 residues of Kv7.1 channels by cysteine and recorded whole-cell mutant channel currents in Xenopus oocytes using the two-electrode voltage-clamp technique. In the closed state, disulfide and metal bridges constrain residue S225 (S4 nearby C136 (S1 within the same VSD. In the open state, two neighboring I227 (S4 are constrained at proximity while residue R228 (S4 is confined close to C136 (S1 of an adjacent VSD. Structural modeling predicts that in the closed to open transition, an axial rotation (approximately 190 degrees and outward translation of S4 (approximately 12 A is accompanied by VSD rocking. This large sensor motion changes the intra-VSD S1-S4 interaction to an inter-VSD S1-S4 interaction. These constraints provide a ground for cooperative subunit interactions and suggest a key role of the S1 segment in steering S4 motion during Kv7.1 gating.

  5. A Transformerless Hybrid Active Filter Capable of Complying with Harmonic Guidelines for Medium-Voltage Motor Drives

    Science.gov (United States)

    Kondo, Ryota; Akagi, Hirofumi

    This paper presents a transformerless hybrid active filter that is integrated into medium-voltage adjustable-speed motor drives for fans, pumps, and compressors without regenerative braking. The authors have designed and constructed a three-phase experimental system rated at 400V and 15kW, which is a downscaled model from a feasible 6.6-kV 1-MW motor drive system. This system consists of the hybrid filter connecting a passive filter tuned to the 7th harmonic filter in series with an active filter that is based on a three-level diode-clamped PWM converter, as well as an adjustable-speed motor drive in which a diode rectifier is used as the front end. The hybrid filter is installed on the ac side of the diode rectifier with no line-frequency transformer. The downscaled system has been exclusively tested so as to confirm the overall compensating performance of the hybrid filter and the filtering performance of a switching-ripple filter for mitigating switching-ripple voltages produced by the active filter. Experimental results verify that the hybrid filter achieves harmonic compensation of the source current in all the operating regions from no-load to the rated-load conditions, and that the switching-ripple filter reduces the switching-ripple voltages as expected.

  6. High Voltage in Noble Liquids for High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Rebel, B. [Fermilab; Bernard, E. [Yale U.; Faham, C. H. [LBL, Berkeley; Ito, T. M. [Los Alamos; Lundberg, B. [Maryland U.; Messina, M. [Columbia U.; Monrabal, F. [Valencia U., IFIC; Pereverzev, S. P. [LLNL, Livermore; Resnati, F. [Zurich, ETH; Rowson, P. C. [SLAC; Soderberg, M. [Fermilab; Strauss, T. [Bern U.; Tomas, A. [Imperial Coll., London; Va' vra, J. [SLAC; Wang, H. [UCLA

    2014-08-22

    A workshop was held at Fermilab November 8-9, 2013 to discuss the challenges of using high voltage in noble liquids. The participants spanned the fields of neutrino, dark matter, and electric dipole moment physics. All presentations at the workshop were made in plenary sessions. This document summarizes the experiences and lessons learned from experiments in these fields at developing high voltage systems in noble liquids.

  7. Flange joint system for SRF cavities utilizing high force spring clamps for low particle generation

    Science.gov (United States)

    None

    2017-09-05

    A flange joint system for SRF cavities. The flange joint system includes a set of high force spring clamps that produce high force on the simple flanges of Superconducting Radio Frequency (SRF) cavities to squeeze conventional metallic seals. The system establishes the required vacuum and RF-tight seal with minimum particle contamination to the inside of the cavity assembly. The spring clamps are designed to stay within their elastic range while being forced open enough to mount over the flange pair. Upon release, the clamps have enough force to plastically deform metallic seal surfaces and continue to a new equilibrium sprung dimension where the flanges remain held against one another with enough preload such that normal handling will not break the seal.

  8. Complete low power controller for high voltage power systems

    International Nuclear Information System (INIS)

    Sumner, R.; Blanar, G.

    1997-01-01

    The MHV100 is a custom CMOS integrated circuit, developed for the AMS experiment. It provides complete control for a single channel high voltage (HV) generator and integrates all the required digital communications, D to A and A to D converters, the analog feedback loop and output drivers. This chip has been designed for use in both distributed high voltage systems or for low cost single channel high voltage systems. The output voltage and current range is determined by the external components

  9. Stable operation of a high-power piezoelectric transformer comprising two identical bolt-clamped Langevin-type transducers and a stepped horn

    Science.gov (United States)

    Adachi, Kazunari; Suzuki, Kohei; Shibamata, Yuki

    2018-06-01

    We previously developed a 100 W piezoelectric transformer comprising two identical bolt-clamped Langevin-type transducers (BLTs) and a stepped horn whose cross-sectional area ratio determines the specified step-up voltage transformation ratio. Unlike conventional piezoelectric transformers, this transformer is driven at a frequency quite near its mechanical resonance, and thus can be mechanically held firmly at its clearly identified vibratory node without mechanical energy loss. However, it has been revealed that the high-power operation of the transformer often becomes very unstable owing to the “jumping and dropping” phenomena first found by Takahashi and Hirose [Jpn. J. Appl. Phys. 31, 3055 (1992)]. To avoid this instability, we have investigated the peculiar phenomena, and found that they can be attributed to a heavily distorted electric field inside the piezoelectric ceramic disks of the BLT on the primary side of the transformer being driven by a low-impedance voltage source near the mechanical resonance. The resultant concentration of the electric field leads to the local reversal of piezoelectric polarization in every half period of the vibration, viz., the instability. Consequently, we have developed a scheme for the steady high-power operation of this type of piezoelectric transformer and examined its validity experimentally. The method has eventually improved the linearity and power transfer efficiency of the transformer significantly.

  10. System for high-voltage control detectors with large number photomultipliers

    International Nuclear Information System (INIS)

    Donskov, S.V.; Kachanov, V.A.; Mikhajlov, Yu.V.

    1985-01-01

    A simple and inexpensive on-line system for hihg-voltage control which is designed for detectors with a large number of photomultipliers is developed and manufactured. It has been developed for the GAMC type hodoscopic electromagnetic calorimeters, comprising up to 4 thousand photomultipliers. High voltage variation is performed by a high-speed potentiometer which is rotated by a microengine. Block-diagrams of computer control electronics are presented. The high-voltage control system has been used for five years in the IHEP and CERN accelerator experiments. The operation experience has shown that it is quite simple and convenient in operation. In case of about 6 thousand controlled channels in both experiments no potentiometer and microengines failures were observed

  11. NIMBY, CLAMP, and the location of new nuclear-related facilities: U.S. national and 11 site-specific surveys.

    Science.gov (United States)

    Greenberg, Michael R

    2009-09-01

    Public and political opposition have made finding locations for new nuclear power plants, waste management, and nuclear research and development facilities a challenge for the U.S. government and the nuclear industry. U.S. government-owned properties that already have nuclear-related activities and commercial nuclear power generating stations are logical locations. Several studies and utility applications to the Nuclear Regulatory Commission suggest that concentrating locations at major plants (CLAMP) has become an implicit siting policy. We surveyed 2,101 people who lived within 50 miles of 11 existing major nuclear sites and 600 who lived elsewhere in the United States. Thirty-four percent favored CLAMP for new nuclear power plants, 52% for waste management facilities, and 50% for new nuclear laboratories. College educated, relatively affluent male whites were the strongest CLAMP supporters. They disproportionately trusted those responsible for the facilities and were not worried about existing nuclear facilities or other local environmental issues. Notably, they were concerned about continuing coal use. Not surprisingly, CLAMP proponents tended to be familiar with their existing local nuclear site. In short, likely CLAMP sites have a large and politically powerful core group to support a CLAMP policy. The challenge to proponents of nuclear technologies will be to sustain this support and expand the base among those who clearly are less connected and receptive to new nearby sites.

  12. Statistical characteristics of transient enclosure voltage in ultra-high-voltage gas-insulated switchgear

    Science.gov (United States)

    Cai, Yuanji; Guan, Yonggang; Liu, Weidong

    2017-06-01

    Transient enclosure voltage (TEV), which is a phenomenon induced by the inner dielectric breakdown of SF6 during disconnector operations in a gas-insulated switchgear (GIS), may cause issues relating to shock hazard and electromagnetic interference to secondary equipment. This is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage (UHV) substations. In this paper, the statistical characteristics of TEV at UHV level are collected from field experiments, and are analyzed and compared to those from a repeated strike process. The TEV waveforms during disconnector operations are recorded by a self-developed measurement system first. Then, statistical characteristics, such as the pulse number, duration of pulses, frequency components, magnitude and single pulse duration, are extracted. The transmission line theory is introduced to analyze the TEV and is validated by the experimental results. Finally, the relationship between the TEV and the repeated strike process is analyzed. This proves that the pulse voltage of the TEV is proportional to the corresponding breakdown voltage. The results contribute to the definition of the standard testing waveform of the TEV, and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.

  13. Euglycemic clamp insulin sensitivity and longitudinal systolic blood pressure

    DEFF Research Database (Denmark)

    Petrie, John R; Malik, Muhammad Omar; Balkau, Beverley

    2013-01-01

    and Cardiovascular disease (RISC) study, we measured insulin sensitivity (M/I) using the euglycemic clamp technique in 1073 healthy European adults (587 women, 486 men) aged 30 to 60 years followed up 3 years later. Systolic BP (SBP) at baseline was higher in insulin-resistant women (ie, those in the low sex...

  14. Cellular elements for seeing in the dark: voltage-dependent conductances in cockroach photoreceptors

    Directory of Open Access Journals (Sweden)

    Salmela Iikka

    2012-08-01

    Full Text Available Abstract Background The importance of voltage-dependent conductances in sensory information processing is well-established in insect photoreceptors. Here we present the characterization of electrical properties in photoreceptors of the cockroach (Periplaneta americana, a nocturnal insect with a visual system adapted for dim light. Results Whole-cell patch-clamped photoreceptors had high capacitances and input resistances, indicating large photosensitive rhabdomeres suitable for efficient photon capture and amplification of small photocurrents at low light levels. Two voltage-dependent potassium conductances were found in the photoreceptors: a delayed rectifier type (KDR and a fast transient inactivating type (KA. Activation of KDR occurred during physiological voltage responses induced by light stimulation, whereas KA was nearly fully inactivated already at the dark resting potential. In addition, hyperpolarization of photoreceptors activated a small-amplitude inward-rectifying (IR current mediated at least partially by chloride. Computer simulations showed that KDR shapes light responses by opposing the light-induced depolarization and speeding up the membrane time constant, whereas KA and IR have a negligible role in the majority of cells. However, larger KA conductances were found in smaller and rapidly adapting photoreceptors, where KA could have a functional role. Conclusions The relative expression of KA and KDR in cockroach photoreceptors was opposite to the previously hypothesized framework for dark-active insects, necessitating further comparative work on the conductances. In general, the varying deployment of stereotypical K+ conductances in insect photoreceptors highlights their functional flexibility in neural coding.

  15. Low Voltage Ride-Through Capability of a Single-Stage Single-Phase Photovoltaic System Connected to the Low-Voltage Grid

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede

    2013-01-01

    The progressively growing of single-phase photovoltaic (PV) systems makes the Distribution System Operators (DSO) to update or revise the existing grid codes in order to guarantee the availability, quality and reliability of the electrical system. It is expected that the future PV systems connected...... to the low-voltage grid will be more active with functionalities of low voltage ride-through (LVRT) and the grid support capability, which is not the case today. In this paper, the operation principle is demonstrated for a single-phase grid-connected PV system in low voltage ride through operation in order...... to map future challenges. The system is verified by simulations and experiments. Test results show that the proposed power control method is effective and the single-phase PV inverters connected to low-voltage networks are ready to provide grid support and ride-through voltage fault capability...

  16. Estimates for lower order eigenvalues of a clamped plate problem

    OpenAIRE

    Cheng, Qing-Ming; Huang, Guangyue; Wei, Guoxin

    2009-01-01

    For a bounded domain $\\Omega$ in a complete Riemannian manifold $M^n$, we study estimates for lower order eigenvalues of a clamped plate problem. We obtain universal inequalities for lower order eigenvalues. We would like to remark that our results are sharp.

  17. In-situ experimental characterization of the clamping pressure effects on low temperature polymer electrolyte membrane electrolysis International Journal of Hydrogen Energy

    DEFF Research Database (Denmark)

    Al Shakhshir, Saher; Cui, Xiaoti; Frensch, Steffen Henrik

    2017-01-01

    as a gas with the circulating water. The effects of clamping pressure (Pc) on the LT-PEME cell performance, polarization resistances, and hydrogen and water crossover through the membrane, and hydrogen and oxygen production rate are studied. A 50 cm2 active area LT-PEME cell designed and manufactured......-PEME splits water into hydrogen and oxygen when the voltage is applied between anode and cathode. Electrical current forces the positively charged ions to migrate to negatively charged cathode through PEM, where hydrogen is produced. Meanwhile, oxygen is produced at the anode side electrode and escapes...... in house is utilized in this work. Higher Pc has shown higher cell performance this refers to lower ohmic and activation resistances. Water crossover from anode to cathode is slightly decreased at higher Pc resulting in a slight decrease in hydrogen crossover from cathode to anode. Also, the percentage...

  18. 33 CFR 183.532 - Clips, straps, and hose clamps.

    Science.gov (United States)

    2010-07-01

    ... resistant material; and (2) Not cut or abrade the fuel line. (b) If tested in accordance with the fire test under § 183.590, a hose clamp installed on a fuel line system requiring metallic fuel lines or “USCG... (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Equipment Standards § 183.532 Clips...

  19. Inductive voltage adder (IVA) for submillimeter radius electron beam

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Poukey, J.W.; Maenchen, J.E.

    1996-01-01

    The authors have already demonstrated the utility of inductive voltage adder accelerators for production of small-size electron beams. In this approach, the inductive voltage adder drives a magnetically immersed foilless diode to produce high-energy (10--20 MeV), high-brightness pencil electron beams. This concept was first demonstrated with the successful experiments which converted the linear induction accelerator RADLAC II into an IVA fitted with a small 1-cm radius cathode magnetically immersed foilless diode (RADLAC II/SMILE). They present here first validations of extending this idea to mm-scale electron beams using the SABRE and HERMES-III inductive voltage adders as test beds. The SABRE experiments are already completed and have produced 30-kA, 9-MeV electron beams with envelope diameter of 1.5-mm FWHM. The HERMES-III experiments are currently underway

  20. Voltage distribution in tapered winding of tesla-transformer during discharge process of PFL

    International Nuclear Information System (INIS)

    Xin Jiaqi; Chang Anbi; Li Mingjia; Kang Qiang

    2007-01-01

    The operation principle of integral construction of Tesla transformer and PFL was investigated in Tesla-transformer-type accelerator. Experiment was carried out on Tesla transformer's secondary winding to study the impulse voltage distribution while PFL was discharging. The regularities of turn-ground voltage distribution and interturn voltage distribution were summarized. Voltage distribution within PFL was calculated and it was compared with the experimental result. Structural winding of parallel coils in the head, parallel coils in the end and shading ring were used to improve voltage distribution and that was testified by experiment. The results indicate that taper winding doesn't effect electric field within PFL, the turn-ground voltage appears linearly, the interturn voltage fluctuates seriously and it is the biggest in head of winding. The three optimized methods help to depress oscillation, the structural winding of parallel coils in the head decreases the interturn voltage in head of winding remark-ably and the parallel coils in the end decrease the interturn voltage in the end. (authors)

  1. Effects of tacrolimus on action potential configuration and transmembrane ion currents in canine ventricular cells.

    Science.gov (United States)

    Szabó, László; Szentandrássy, Norbert; Kistamás, Kornél; Hegyi, Bence; Ruzsnavszky, Ferenc; Váczi, Krisztina; Horváth, Balázs; Magyar, János; Bányász, Tamás; Pál, Balázs; Nánási, Péter P

    2013-03-01

    Tacrolimus is a commonly used immunosuppressive agent which causes cardiovascular complications, e.g., hypertension and hypertrophic cardiomyopathy. In spite of it, there is little information on the cellular cardiac effects of the immunosuppressive agent tacrolimus in larger mammals. In the present study, therefore, the concentration-dependent effects of tacrolimus on action potential morphology and the underlying ion currents were studied in canine ventricular cardiomyocytes. Standard microelectrode, conventional whole cell patch clamp, and action potential voltage clamp techniques were applied in myocytes enzymatically dispersed from canine ventricular myocardium. Tacrolimus (3-30 μM) caused a concentration-dependent reduction of maximum velocity of depolarization and repolarization, action potential amplitude, phase-1 repolarization, action potential duration, and plateau potential, while no significant change in the resting membrane potential was observed. Conventional voltage clamp experiments revealed that tacrolimus concentrations ≥3 μM blocked a variety of ion currents, including I(Ca), I(to), I(K1), I(Kr), and I(Ks). Similar results were obtained under action potential voltage clamp conditions. These effects of tacrolimus developed rapidly and were fully reversible upon washout. The blockade of inward currents with the concomitant shortening of action potential duration in canine myocytes is the opposite of those observed previously with tacrolimus in small rodents. It is concluded that although tacrolimus blocks several ion channels at higher concentrations, there is no risk of direct interaction with cardiac ion channels when applying tacrolimus in therapeutic concentrations.

  2. Role of clamping tube thoracostomy prior to removal in non-cardiac thoracic trauma

    International Nuclear Information System (INIS)

    Rasheed, M.A.; Majeed, F.A.; Naz, A.

    2016-01-01

    The frequently encountered thoracic trauma in surgical emergencies is a major cause of mortality and morbidity. Eighty percent of thoracic trauma can be managed by simple insertion of tube thoracostomy. Though guidelines for insertion are comprehensively explained in literature, an ideal algorithm for discontinuation is not available. A standard and safe defined protocol would eliminate hesitancy in confident removal among general surgeons. The objective of this study was to determine role of clamping trial prior to removal in terms of frequency of recurrent pneumothorax. Methods: This study was conducted in department of Surgery Combined military hospital/Military Hospital Rawalpindi from April 2013 to March 2014. Total 180 patients with blunt or penetrating thoracic trauma were included in the study. Chest tube (28-36 Fr) was inserted in Trauma centre under strict asepsis. Tubes were then connected to under water seal for minimum six hours. Patients were randomly divided in two equal groups (90 in each). In Group A, Clamping trial was given before attempting removal while in Group B, tube was removed immediately without clamping trial. Patients of both groups were observed two hourly for development of recurrent pneumothorax. Data was analysed using SPSS-18. Results: The comparison of frequency of recurrent pneumothorax in Group A (9 patients, 10%) and in Group B (4 patients, 4.5%) was not found to be statistically significant. (p-value 2.073). Conclusion: Clamping trial is unnecessary prior to removal of tube thoracostomy in blunt and penetrating non-cardiac thoracic trauma in terms of recurrent pneumothorax. (author)

  3. Maximum permissible voltage of YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Wen, J.; Lin, B.; Sheng, J.; Xu, J.; Jin, Z. [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Hong, Z., E-mail: zhiyong.hong@sjtu.edu.cn [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Wang, D.; Zhou, H.; Shen, X.; Shen, C. [Qingpu Power Supply Company, State Grid Shanghai Municipal Electric Power Company, Shanghai (China)

    2014-06-15

    Highlights: • We examine three kinds of tapes’ maximum permissible voltage. • We examine the relationship between quenching duration and maximum permissible voltage. • Continuous I{sub c} degradations under repetitive quenching where tapes reaching maximum permissible voltage. • The relationship between maximum permissible voltage and resistance, temperature. - Abstract: Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (I{sub c}) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the I{sub c} degradation or burnout happens. YBCO coated conductors test in the experiment are from American superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.

  4. Experience with High Voltage Tests of the W7-X Magnets in Paschen-Minimum Conditions

    International Nuclear Information System (INIS)

    Petersen-Zarling, B.M.; Risse, K.; Viebke, H.; Gustke, D.; Ehmler, H.; Baldzuhn, J.; Sborchia, C.; Scheller, H.

    2006-01-01

    The W7-X machine is a low-shear stellarator of the Wendelstein line, which is being assembled at the IPP Branch Institute of Greifswald, Germany. The machine features a superconducting magnet system with 50 non-planar and 20 planar magnets operated at about 6 T and discharged with peak voltage levels up to 6 kV. Following the factory tests, the magnets are delivered to CEA Saclay, France, for the final acceptance tests at cryogenic condition. A series of high voltage tests in air and vacuum are part of the final acceptance test. During these tests the quality of the insulation, especially the hand-wrapped ground insulation in the termination area, has proven not to be adequate. In order to improve the reliability of the insulation system and detect defects for early repair, high voltage tests in reduced pressure of air (Paschen-minimum conditions) have been added as part of the factory acceptance procedure. This has been implemented in the vacuum chambers of BNN/Ansaldo for the test of the 50 non-planar coils, while other tests have been carried out at CEA/Saclay after cold testing. IPP has also installed a vacuum tank to perform Paschen tests during the preparation of all the coils for assembly, including also the 20 planar coils which cannot be tested at the manufacturer Tesla. These tests have proven to be a powerful tool to detect hidden insulation defects and void/cavities in the primary impregnation system, which could not be detected otherwise with the standard high voltage tests. This paper will summarize the background and experience accumulated in about 2 years of Paschen tests on the W7-X coils, including a description of the equipment, main results and statistics, weak points detected and repaired on the coils, and possibilities of improvements in the development and production of the W7-X magnets. The importance and the need of Paschen tests as part of the acceptance procedure for superconducting magnets to be used in future projects will also be

  5. Mycobacterium tuberculosis class II apurinic/apyrimidinic-endonuclease/3'-5' exonuclease III exhibits DNA regulated modes of interaction with the sliding DNA β-clamp.

    Science.gov (United States)

    Khanam, Taran; Rai, Niyati; Ramachandran, Ravishankar

    2015-10-01

    The class-II AP-endonuclease (XthA) acts on abasic sites of damaged DNA in bacterial base excision repair. We identified that the sliding DNA β-clamp forms in vivo and in vitro complexes with XthA in Mycobacterium tuberculosis. A novel 239 QLRFPKK245 motif in the DNA-binding domain of XthA was found to be important for the interactions. Likewise, the peptide binding-groove (PBG) and the C-terminal of β-clamp located on different domains interact with XthA. The β-clamp-XthA complex can be disrupted by clamp binding peptides and also by a specific bacterial clamp inhibitor that binds at the PBG. We also identified that β-clamp stimulates the activities of XthA primarily by increasing its affinity for the substrate and its processivity. Additionally, loading of the β-clamp onto DNA is required for activity stimulation. A reduction in XthA activity stimulation was observed in the presence of β-clamp binding peptides supporting that direct interactions between the proteins are necessary to cause stimulation. Finally, we found that in the absence of DNA, the PBG located on the second domain of the β-clamp is important for interactions with XthA, while the C-terminal domain predominantly mediates functional interactions in the substrate's presence. © 2015 John Wiley & Sons Ltd.

  6. Coordinated Voltage Control of Distributed PV Inverters for Voltage Regulation in Low Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

    2017-01-01

    This paper reviews and analyzes the existing voltage control methods of distributed solar PV inverters to improve the voltage regulation and thereby the hosting capacity of a low-voltage distribution network. A novel coordinated voltage control method is proposed based on voltage sensitivity...... optimization. The proposed method is used to calculate the voltage bands and droop settings of PV inverters at each node by the supervisory controller. The local controller of each PV inverter implements the volt/var control and if necessary, the active power curtailment as per the received settings and based...... on measured local voltages. The advantage of the proposed method is that the calculated reactive power and active power droop settings enable fair contribution of the PV inverters at each node to the voltage regulation. Simulation studies are conducted using DigSilent Power factory software on a simplified...

  7. The Effect of PRGF on Healing of Clamp-Induced Tendinopathy in Animals

    Directory of Open Access Journals (Sweden)

    Uğur Diliçıkık

    2018-04-01

    Material and Methods: A preliminary study was designed to obtain more apparent tendinopathy changes in the subculture. Histopathologically, second level compression with a clamp for 1 minute followed by releasing for 3 minutes applying the same mechanical stimulus procedure for four times, was defined as the optimal compression mode for the most optimal damage in terms of tendinopathy. Thirty-four female Sprague Downey type rats were divided into five separate groups and clamped tendon damage was formed on unilateral (left Acchilles tendons. The first group was a control group (Kontrol: CN; in the second group tissue specimens were taken from the rats immediately after being clamped (K-0; from the group 3, tissue samples were taken 1 week after clamping (K-7. Immediately after the tendinopathy model was applied to the animals in the fourth group (PRGF, the PRGF injection was performed to the subjects from the blood that was obtained from the control group, while an isotonic saline solution was injected into the subjects in the fifth group (SF, and tissue samples from both groups were obtained 1 week after. Results: The samples were examined by means of a transmission electron microscope. In the K-0 group among the collagenous fibers, vacuoles are observed in the cytoplasm of the edematous areas and fibrocytes, and in comparison, with K-7 and SF group there was a significant increase in fibroblast and collagen fiber synthesis in the PRGF-treated group. Furthermore, fibroblast and new collagen synthesis were observed to be increased in K-7 and SF groups. An intense increase in organelle levels was observed in PRGF group fibroblasts. Conclusion: This data suggests that PRGF may provide a better healing response in tendons with limited healing and circulation, which enhances the activation in the cells at the beginning of the healing process.

  8. Voltage-gated Na+ currents in human dorsal root ganglion neurons

    Science.gov (United States)

    Zhang, Xiulin; Priest, Birgit T; Belfer, Inna; Gold, Michael S

    2017-01-01

    Available evidence indicates voltage-gated Na+ channels (VGSCs) in peripheral sensory neurons are essential for the pain and hypersensitivity associated with tissue injury. However, our understanding of the biophysical and pharmacological properties of the channels in sensory neurons is largely based on the study of heterologous systems or rodent tissue, despite evidence that both expression systems and species differences influence these properties. Therefore, we sought to determine the extent to which the biophysical and pharmacological properties of VGSCs were comparable in rat and human sensory neurons. Whole cell patch clamp techniques were used to study Na+ currents in acutely dissociated neurons from human and rat. Our results indicate that while the two major current types, generally referred to as tetrodotoxin (TTX)-sensitive and TTX-resistant were qualitatively similar in neurons from rats and humans, there were several differences that have important implications for drug development as well as our understanding of pain mechanisms. DOI: http://dx.doi.org/10.7554/eLife.23235.001 PMID:28508747

  9. Outside-out "sniffer-patch" clamp technique for in situ measures of neurotransmitter release.

    Science.gov (United States)

    Muller-Chrétien, Emilie

    2014-01-01

    The mechanism underlying neurotransmitter release is a critical research domain for the understanding of neuronal network function; however, few techniques are available for the direct detection and measurement of neurotransmitter release. To date, the sniffer-patch clamp technique is mainly used to investigate these mechanisms from individual cultured cells. In this study, we propose to adapt the sniffer-patch clamp technique to in situ detection of neurosecretion. Using outside-out patches from donor cells as specific biosensors plunged in acute cerebral slices, this technique allows for proper detection and quantification of neurotransmitter release at the level of the neuronal network.

  10. Analysis of failed and nickel-coated 3093 beam clamp components at the East Tennessee Technology Park (ETTP).

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D.; Pappacena, K.; Gaviria, J.; Burtsteva, T.; Nuclear Engineering Division

    2010-10-11

    The U.S. Department of Energy and its contractor, Bechtel Jacobs Company (BJC), are undertaking a major effort to clean up the former gaseous diffusion facility (K-25) located in Oak Ridge, TN. The decontamination and decommissioning activities require systematic removal of contaminated equipment and machinery followed by demolition of the buildings. As part of the cleanup activities, a beam clamp, used for horizontal life lines (HLLs) for fall protection, was discovered to be fractured during routine inspection. The beam clamp (yoke and D-ring) was a component in the HLL system purchased from Reliance Industries LLC. Specifically, the U-shaped stainless steel yoke of the beam clamp failed in a brittle mode at under less than 10% of the rated design capacity of 14,500 lb. The beam clamp had been in service for approximately 16 months. Bechtel Jacobs approached Argonne National Laboratory to assist in identifying the root cause of the failure of the beam clamp. The objectives of this study were to (1) review the prior reports and documents on the subject, (2) understand the possible failure mechanism(s) that resulted in the failed beam clamp components, (3) recommend approaches to mitigate the failure mechanism(s), and (4) evaluate the modified beam clamp assemblies. Energy dispersive x-ray analysis and chemical analysis of the corrosion products on the failed yoke and white residue on an in-service yoke indicated the presence of zinc, sulfur, and calcium. Analysis of rainwater in the complex, as conducted by BJC, indicated the presence of sulfur and calcium. It was concluded that, as a result of galvanic corrosion, zinc from the galvanized components of the beam clamp assembly (D-ring) migrated to the corroded region in the presence of the rainwater. Under mechanical stress, the corrosion process would have accelerated, resulting in the catastrophic failure of the yoke. As suggested by Bechtel Jacobs personnel, hydrogen embrittlement as a consequence of corrosion

  11. High Voltage Homemade Capacitor Charger for Plasma Focus System

    International Nuclear Information System (INIS)

    Abdul Halim Baijan; Azaman Ahmad; Rokiah Mohd Sabri; Siti Aiasah Hashim; Mohd Rizal Md Chulan; Wah, L.K.; Azhar Ahmad; Rosli Che Ros; Mohd Faiz Mohd Zin

    2015-01-01

    A high voltage capacitor charger has been designed and built to replace a high voltage charger type General Atomics CCDs Power Supply which was damaged. The fabrication design was using materials which were easily available in the local market. Among the main components of the high-voltage charger is a transformer for neon lights, variable transformer rated 0 - 240 V 1 KVA, and 240 V transformer isolator. The results of experiments that have been conducted shows that a homemade capacitor charger was able to charge high voltage capacitors up to the required voltage of which was 12 kV. However the time taken for charging is quite long, up to more than 6 minutes. (author)

  12. Superconducting cyclotron deflector conditioning status - an experience with high voltage

    International Nuclear Information System (INIS)

    Ghosh, Subhash; Chattopadhyay, Subrata; Bhattacharjee, Tanushyam; De, Anirban; Paul, Santanu; Pal, Gautam; Saha, Subimal; Mallik, C.; Bhandari, R.K.

    2009-01-01

    In this paper we report about the status of the electrostatic deflector which will be used in K500 superconducting cyclotron at VECC, Kolkata. For extraction of beams from superconducting cyclotron we have to achieve 130 kV/cm. Titanium and tungsten are used for anode and septum respectively. The deflector fits within the median plane of the superconducting magnet. We report here the voltage limit, sparking rates, dark current levels and the effects observed on conditioning. For commissioning of the superconducting cyclotron, the plan is to accelerate Neon beam of 50 MeV/n for which the required extraction voltage is 81 kV/cm and we reached up to 110 kV/cm. The conditioning test chamber is maintained at a pressure of 8.0 x 10 -7 mbar. (author)

  13. Practical experience in the determination of the tube voltage using the Ardran-Crooks cassette

    International Nuclear Information System (INIS)

    Ewen, K.; Roesner, W.

    1984-01-01

    Within the framework of quality control measures in X-ray diagnostics and therapy, it is desirable to employ for the determination of tube voltage (e.g. in diagnostic X-ray equipment) methods which are as economical as possible while saving time and being simple to apply in spite of the fact that they are as highly accurate as ever possible. The absorber method described here, represented by the Ardran-Crooks cassette, possesses the advantage of low price and easy application. However, if it is operated in such a way that time is saved (assessment by the eye), it is not so accurate, whereas in accurate operation (assessment via luxmeter) it does require a relatively large amount of time. After the film has been exposed, it is necessary to estimate or measure the agreement of blackenings on one and the same film in order to determine the tube voltage. This voltage is then read off by means of a calibration curve. The error in the determination of the tube voltage via the Ardran-Crooks cassette depends on the accuracy of the calibration curve, which, in turn, depends on the number of measurements performed when producing the curve, and on the correct voltage of the standard X-ray equipment used in producing the calibration curve. In addition, assessment by eye adds a total error of 2.3% to 8%, depending on the amount of tube voltage. If the luxmeter is used instead of the eye, this additional error is less than 1% in relation to the magnitude of the tube voltage. (orig./BWU) [de

  14. space vector pulse width modulation of a multi-level diode clamped

    African Journals Online (AJOL)

    ES Obe

    step by step development of MATLAB /SIMULINK modeling of the space vector ..... Pulse Width Mod. of Multi-Level Diode Clamped Converter 119 powergui. Discrete, .... Load. Figure 22: Block diagram of the three level DCC design. 3 LEVEL ...

  15. Mitigation of Voltage Sags in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage p....... The compensation of voltage sags in the different parts of CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0.......Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage...... problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate voltage sags in the CIGRE Low Voltage (LV) test network and networks like this. The voltage sags, for the tested cases in the CIGRE LV test network are mainly due to three phase faults...

  16. The hypertriglyceridemic clamp technique. Studies using long-chain and structured triglyceride emulsions in healthy subjects.

    Science.gov (United States)

    Nordenström, Jörgen; Thörne, Anders; Aberg, Wiveca; Carneheim, Claes; Olivecrona, Thomas

    2006-11-01

    In a randomized crossover study, plasma kinetics of 2 different types of fat emulsions were studied in 8 healthy volunteers by using a hypertriglyceridemic clamp technique. The method involves the stabilization of serum triglyceride (TG) concentration during 180 minutes at a predetermined level (4 mmol/L) by adjustment of TG infusion rate by repeated online measurements of serum TG concentration. The fat emulsions under study were a long-chain fatty acid triglyceride (LCT) emulsion (Intralipid 20%, Fresenius Kabi, Sweden) and a structured triglyceride (STG) emulsion (Structolipid 20%, Fresenius Kabi) where medium- and long-chain fatty acids have been interesterified within a TG molecule. The hypertriglyceridemic clamp was found to have acceptable reproducibility when tested in 3 healthy individuals on 2 different occasions, as similar steady-state TG levels were obtained by infusing similar amounts of fat. The average (+/-SEM) TG concentration during the 180-minute clamp was similar for STGs and LCTs (4.0 +/- 0.1 vs 3.9 +/- 0.1 mmol/L; not significant), but the amount of fat that had to be infused was significantly higher during STG than during LCT clamping (0.31 +/- 0.04 vs 0.21 +/- 0.02 g TG per minute; P < .05). Higher serum levels of free fatty acids (1.80 +/- 0.13 vs 0.96 +/- 0.09 mmol/L; P < .05), free glycerol (1.30 +/- 0.07 vs 0.76 +/- 0.08 mmol/L; P < .001), and beta-OH butyrate (1.61 +/- 0.44 vs 1.17 +/- 0.23 mmol/L; not significant) were obtained at the end of the clamp during infusion of STGs compared with LCTs. During infusion of STGs the medium-chain fatty acids octanoic (C:8) and decanoic acid (C:10) constituted approximately half of circulating fatty acids that correspond to the compositional ratio of the emulsion. Plasma lipoprotein lipase (LPL) concentration was higher during STG than during LCT clamping (6.06 +/- 0.62 vs 3.15 +/- 0.40 mU/mL; P < .05), and there was a positive correlation between the mean LPL concentration and the amount of

  17. Mutations in the voltage-sensing domain affect the alternative ion permeation pathway in the TRPM3 channel.

    Science.gov (United States)

    Held, Katharina; Gruss, Fabian; Aloi, Vincenzo Davide; Janssens, Annelies; Ulens, Chris; Voets, Thomas; Vriens, Joris

    2018-03-31

    mutations in S4 can create an analogous 'omega' pore, we performed site-directed mutagenesis studies and patch clamp experiments to identify amino acid residues involved in the formation of the non-canonical pore in TRPM3. Based on our results, we pinpoint four residues in S4 (W982, R985, D988 and G991) as crucial determinants of the properties of the alternative ion permeation pathway. © 2018 KU Leuven The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

  18. Development of a New Cascade Voltage-Doubler for Voltage Multiplication

    OpenAIRE

    Toudeshki, Arash; Mariun, Norman; Hizam, Hashim; Abdul Wahab, Noor Izzri

    2014-01-01

    For more than eight decades, cascade voltage-doubler circuits are used as a method to produce DC output voltage higher than the input voltage. In this paper, the topological developments of cascade voltage-doublers are reviewed. A new circuit configuration for cascade voltage-doubler is presented. This circuit can produce a higher value of the DC output voltage and better output quality compared to the conventional cascade voltage-doubler circuits, with the same number of stages.

  19. Analysis of NSTX TF Joint Voltage Measurements

    International Nuclear Information System (INIS)

    Woolley R

    2005-01-01

    This report presents findings of analyses of recorded current and voltage data associated with 72 electrical joints operating at high current and high mechanical stress. The analysis goal was to characterize the mechanical behavior of each joint and thus evaluate its mechanical supports. The joints are part of the toroidal field (TF) magnet system of the National Spherical Torus Experiment (NSTX) pulsed plasma device operating at the Princeton Plasma Physics Laboratory (PPPL). Since there is not sufficient space near the joints for much traditional mechanical instrumentation, small voltage probes were installed on each joint and their voltage monitoring waveforms have been recorded on sampling digitizers during each NSTX ''shot''

  20. Effects of clamping force on the water transport and performance of a PEM (proton electrolyte membrane) fuel cell with relative humidity and current density

    International Nuclear Information System (INIS)

    Cha, Dowon; Ahn, Jae Hwan; Kim, Hyung Soon; Kim, Yongchan

    2015-01-01

    The clamping force should be applied to a proton electrolyte membrane (PEM) fuel cell due to its structural characteristics. The clamping force affects the ohmic and mass transport resistances in the PEM fuel cell. In this study, the effects of the clamping force on the water transport and performance characteristics of a PEM fuel cell are experimentally investigated with variations in the relative humidity and current density. The water transport characteristics were analyzed by calculating the net drag coefficient. The ohmic resistance decreased with the increase in the clamping force due to the reduced contact resistance and more even membrane hydration. However, the mass transport resistance increased with the increase in the clamping force due to the gas diffusion layer compression. The net drag coefficient decreased with the increase in the clamping force due to high water back-diffusion. Additionally, the relationship between the total resistance and the net drag coefficient was investigated. - Highlights: • Effects of clamping force on the performance of a PEM fuel cell are investigated. • Water transport characteristics are analyzed using net drag coefficient. • Ohmic resistance decreased with clamping force, but mass transport resistance increased. • Net drag coefficient decreased with the increase in clamping force. • Total resistance was significantly degraded for a net drag coefficient below 0.2.

  1. Suppressing voltage transients in high voltage power supplies

    International Nuclear Information System (INIS)

    Lickel, K.F.; Stonebank, R.

    1979-01-01

    A high voltage power supply for an X-ray tubes includes voltage adjusting means, a high voltage transformer, switch means connected to make and interrupt the primary current of the transformer, and over-voltage suppression means to suppress the voltage transient produced when the current is switched on. In order to reduce the power losses in the suppression means, an impedance is connected in the transformer primary circuit on operation of the switch means and is subsequently short-circuited by a switch controlled by a timer after a period which is automatically adjusted to the duration of the transient overvoltage. (U.K.)

  2. Transmission of power at high voltages

    Energy Technology Data Exchange (ETDEWEB)

    Lane, F J

    1963-01-01

    High voltage transmission is considered to be concerned with circuits and systems operating at or above 132 kV. While the general examination is concerned with ac transmission, dc systems are also included. The choice of voltage for a system will usually involve hazardous assessments of the future requirements of industry, commerce and a changing population. Experience suggests that, if the estimated economic difference between two voltages is not significant, there is good reason to choose the higher voltage, as this will make the better provision for unexpected future expansion. Two principal functions served by transmission circuits in a supply system are: (a) the transportation of energy in bulk from the generator to the reception point in the distribution system; and (b) the interconnection and integration of the generating plant and associated loads. These functions are considered and various types of system are discussed in terms of practicability, viability, quality and continuity of supply. Future developments requiring transmission voltages up to 750 kV will raise many problems which are in the main empirical. Examples are given of the type of problem envisaged and it is suggested that these can only be partially solved by theory and model operation.

  3. Bupivacaine inhibits large conductance, voltage- and Ca2+- activated K+ channels in human umbilical artery smooth muscle cells

    Science.gov (United States)

    Martín, Pedro; Enrique, Nicolás; Palomo, Ana R. Roldán; Rebolledo, Alejandro; Milesi, Veronica

    2012-01-01

    Bupivacaine is a local anesthetic compound belonging to the amino amide group. Its anesthetic effect is commonly related to its inhibitory effect on voltage-gated sodium channels. However, several studies have shown that this drug can also inhibit voltage-operated K+ channels by a different blocking mechanism. This could explain the observed contractile effects of bupivacaine on blood vessels. Up to now, there were no previous reports in the literature about bupivacaine effects on large conductance voltage- and Ca2+-activated K+ channels (BKCa). Using the patch-clamp technique, it is shown that bupivacaine inhibits single-channel and whole-cell K+ currents carried by BKCa channels in smooth muscle cells isolated from human umbilical artery (HUA). At the single-channel level bupivacaine produced, in a concentration- and voltage-dependent manner (IC50 324 µM at +80 mV), a reduction of single-channel current amplitude and induced a flickery mode of the open channel state. Bupivacaine (300 µM) can also block whole-cell K+ currents (~45% blockage) in which, under our working conditions, BKCa is the main component. This study presents a new inhibitory effect of bupivacaine on an ion channel involved in different cell functions. Hence, the inhibitory effect of bupivacaine on BKCa channel activity could affect different physiological functions where these channels are involved. Since bupivacaine is commonly used during labor and delivery, its effects on umbilical arteries, where this channel is highly expressed, should be taken into account. PMID:22688134

  4. External mean flow influence on sound transmission through finite clamped double-wall sandwich panels

    Science.gov (United States)

    Liu, Yu; Catalan, Jean-Cédric

    2017-09-01

    This paper studies the influence of an external mean flow on the sound transmission through finite clamped double-wall sandwich panels lined with poroelastic materials. Biot's theory is employed to describe wave propagation in poroelastic materials and various configurations of coupling the poroelastic layer to the facing plates are considered. The clamped boundary of finite panels are dealt with by the modal superposition theory and the weighted residual (Garlekin) method, leading to a matrix equation solution for the sound transmission loss (STL) through the structure. The theoretical model is validated against existing theories of infinite sandwich panels with and without an external flow. The numerical results of a single incident wave show that the external mean flow has significant effects on the STL which are coupled with the clamped boundary effect dominating in the low-frequency range. The external mean flow also influences considerably the limiting incidence angle of the panel system and the effect of the incidence angle on the STL. However, the influences of the azimuthal angle and the external flow orientation are negligible.

  5. Estimation of endogenous glucose production during hyperinsulinemic-euglycemic glucose clamps. Comparison of unlabeled and labeled exogenous glucose infusates

    International Nuclear Information System (INIS)

    Finegood, D.T.; Bergman, R.N.; Vranic, M.

    1987-01-01

    Tracer methodology has been applied extensively to the estimation of endogenous glucose production (Ra) during euglycemic glucose clamps. The accuracy of this approach has been questioned due to the observation of significantly negative estimates for Ra when insulin levels are high. We performed hyperinsulinemic (300 microU/ml)-euglycemic glucose clamps for 180 min in normal dogs and compared the standard approach, an unlabeled exogenous glucose infusate (cold GINF protocol, n = 12), to a new approach in which a tracer (D-[3- 3 H]glucose) was added to the exogenous glucose used for clamping (hot GINF protocol, n = 10). Plasma glucose, insulin and glucagon concentrations, and glucose infusion rates were similar for the two protocols. Plasma glucose specific activity was 20 +/- 1% of basal (at 120-180 min) in the cold GINF studies, and 44 +/- 3 to 187 +/- 5% of basal in the hot GINF studies. With the one-compartment, fixed pool volume model of Steele, Ra for the cold GINF studies was -2.4 +/- 0.7 mg X min-1 X kg-1 at 25 min and remained significantly negative until 110 min (P less than .05). For the hot GINF studies, Ra was never significantly less than zero (P greater than .05) and was greater than in the cold GINF studies at 20-90 min (P less than .05). There was substantially less between-(78%) and within- (40%) experiment variation for the hot GINF studies compared with the cold GINF studies. An alternate approach (regression method) to the application of the one-compartment model, which allows for a variable and estimable effective distribution volume, yielded Ra estimates that were suppressed 60-100% from basal

  6. Analytical and experimental investigation on transmission loss of clamped double panels: implication of boundary effects.

    Science.gov (United States)

    Xin, F X; Lu, T J

    2009-03-01

    The air-borne sound insulation performance of a rectangular double-panel partition clamp mounted on an infinite acoustic rigid baffle is investigated both analytically and experimentally and compared with that of a simply supported one. With the clamped (or simply supported) boundary accounted for by using the method of modal function, a double series solution for the sound transmission loss (STL) of the structure is obtained by employing the weighted residual (Galerkin) method. Experimental measurements with Al double-panel partitions having air cavity are subsequently carried out to validate the theoretical model for both types of the boundary condition, and good overall agreement is achieved. A consistency check of the two different models (based separately on clamped modal function and simply supported modal function) is performed by extending the panel dimensions to infinite where no boundaries exist. The significant discrepancies between the two different boundary conditions are demonstrated in terms of the STL versus frequency plots as well as the panel deflection mode shapes.

  7. Note: Decoupling design for high frequency piezoelectric ultrasonic transducers with their clamping connections

    Energy Technology Data Exchange (ETDEWEB)

    Wang, F. J., E-mail: wangfujun@tju.edu.cn; Liang, C. M.; Tian, Y. L.; Zhao, X. Y.; Zhang, D. W. [Tianjin Key Laboratory of Equipment Design and Manufacturing Technology, School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China); Zhang, H. J. [Tianjin Key Laboratory of Modern Mechatronics Equipment Technology, School of Mechanical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

    2015-12-15

    This work presents the flexure-mechanism based decoupling design between high frequency piezoelectric ultrasonic transducers and their clamping connections to improve ultrasonic energy transmission efficiency. The ring, prismatic beam, and circular notched hinge based flanges were presented, and the crucial geometric dimensions of the transducers with the flexure decoupling flanges were determined. Finite element analysis (FEA) was carried out to investigate the dynamic characteristics of the transducers. Finally, experiments were conducted to examine and verify the effects of the proposed decoupling flanges. FEA and experimental results show that smaller frequency deviations and larger tip displacement amplitudes have been achieved by using the transducers with the flexure flanges compared with the transducer with a rigid ring-type flange, and thus the ultrasonic transmission efficiency can be improved through the flexure flanges.

  8. Transient voltage sharing in series-coupled high voltage switches

    Directory of Open Access Journals (Sweden)

    Editorial Office

    1992-07-01

    Full Text Available For switching voltages in excess of the maximum blocking voltage of a switching element (for example, thyristor, MOSFET or bipolar transistor such elements are often coupled in series - and additional circuitry has to be provided to ensure equal voltage sharing. Between each such series element and system ground there is a certain parasitic capacitance that may draw a significant current during high-speed voltage transients. The "open" switch is modelled as a ladder network. Analy­sis reveals an exponential progression in the distribution of the applied voltage across the elements. Overstressing thus oc­curs in some of the elements at levels of the total voltage that are significantly below the design value. This difficulty is overcome by grading the voltage sharing circuitry, coupled in parallel with each element, in a prescribed manner, as set out here.

  9. Effects of (−-Gallocatechin-3-Gallate on Tetrodotoxin-Resistant Voltage-Gated Sodium Channels in Rat Dorsal Root Ganglion Neurons

    Directory of Open Access Journals (Sweden)

    Jian-Min Jiang

    2013-05-01

    Full Text Available The (−-gallocatechin-3-gallate (GCG concentration in some tea beverages can account for as much as 50% of the total catechins. It has been shown that catechins have analgesic properties. Voltage-gated sodium channels (Nav mediate neuronal action potentials. Tetrodotoxin inhibits all Nav isoforms, but Nav1.8 and Nav1.9 are relatively tetrodotoxin-resistant compared to other isoforms and functionally linked to nociception. In this study, the effects of GCG on tetrodotoxin-resistant Na+ currents were investigated in rat primary cultures of dorsal root ganglion neurons via the whole-cell patch-clamp technique. We found that 1 μM GCG reduced the amplitudes of peak current density of tetrodotoxin-resistant Na+ currents significantly. Furthermore, the inhibition was accompanied by a depolarizing shift of the activation voltage and a hyperpolarizing shift of steady-state inactivation voltage. The percentage block of GCG (1 μM on tetrodotoxin-resistant Na+ current was 45.1% ± 1.1% in 10 min. In addition, GCG did not produce frequency-dependent block of tetrodotoxin-resistant Na+ currents at stimulation frequencies of 1 Hz, 2 Hz and 5 Hz. On the basis of these findings, we propose that GCG may be a potential analgesic agent.

  10. Feasibility, safety and image quality of cardiac FDG studies during hyperinsulinaemic-euglycaemic clamping

    International Nuclear Information System (INIS)

    Bax, Jeroen J.; Visser, Frans C.; Lingen, Arthur van; Visser, Cees A.; Poldermans, Don; Elhendy, Abdou; Boersma, Eric

    2002-01-01

    Fluorine-18 fluorodeoxyglucose (FDG) imaging for the assessment of myocardial viability has become an integral part of the diagnostic and prognostic work-up of patients with ischaemic cardiomyopathy. To ensure good image quality, in particular in patients with diabetes mellitus, hyperinsulinaemic-euglycaemic clamping has been proposed. In this study we evaluated the safety and the image quality of cardiac FDG imaging during clamping in a large group of patients, including a subgroup with diabetes mellitus. The incidence of viability (on both a segment and a patient basis) was also determined for patients with and without diabetes mellitus. The safety and image quality of cardiac FDG studies during clamping were evaluated in 131 patients, including 19 with diabetes mellitus. Image quality was assessed visually and quantitatively using heart-to-lung (H/L), heart-to-liver (H/Li) and myocardium-to-background (M/B) ratios. Blood samples were drawn at baseline and at the time of FDG injection to determine levels of glucose, free fatty acids and insulin. The metabolic circumstances were optimal for FDG imaging: high insulin levels, low free fatty acid levels and glucose levels in the normal range (levels of substrates were comparable between patients with and patients without diabetes mellitus). No serious side-effects occurred in any patient. Image quality (assessed visually) was good in all patients. The quantitative parameters of image quality (H/L, H/Li and M/B) were comparable between patients with and patients without diabetes mellitus. The incidence of viability was high: 38% of patients without and 58% of patients with diabetes mellitus had substantial viability despite contractile dysfunction. It is concluded that cardiac FDG imaging during clamping is safe and provides excellent image quality, including in patients with diabetes mellitus. The incidence of viability is high, in particular in patients with diabetes mellitus. (orig.)

  11. Influence of non-steady state during isoglycemic hyperinsulinemic clamp in hypertension. A LIFE substudy

    DEFF Research Database (Denmark)

    Olsen, M H; Andersen, U B; Wachtell, K

    1999-01-01

    We wanted to investigate whether time to steady state was reached within 2 h of insulin infusion during isoglycemic hyperinsulinemic clamp, comparing the glucose uptake index (M/IG) with Bergman's insulin sensitivity index (Sip). We performed a 2-h oral glucose tolerance test and a 3-h isoglycemic....... Because the 2-h M/IG correlated strongly with the 3-h Sip with relatively narrow limits of agreement, it is a good measure of insulin sensitivity. However, a 2-h clamp results in lower insulin sensitivity values in elderly, hypertensive patients due to the fact that steady state is not reached...

  12. Voltage-gated sodium channel expression and action potential generation in differentiated NG108-15 cells.

    Science.gov (United States)

    Liu, Jinxu; Tu, Huiyin; Zhang, Dongze; Zheng, Hong; Li, Yu-Long

    2012-10-25

    The generation of action potential is required for stimulus-evoked neurotransmitter release in most neurons. Although various voltage-gated ion channels are involved in action potential production, the initiation of the action potential is mainly mediated by voltage-gated Na+ channels. In the present study, differentiation-induced changes of mRNA and protein expression of Na+ channels, Na+ currents, and cell membrane excitability were investigated in NG108-15 cells. Whole-cell patch-clamp results showed that differentiation (9 days) didn't change cell membrane excitability, compared to undifferentiated state. But differentiation (21 days) induced the action potential generation in 45.5% of NG108-15 cells (25/55 cells). In 9-day-differentiated cells, Na+ currents were mildly increased, which was also found in 21-day differentiated cells without action potential. In 21-day differentiated cells with action potential, Na+ currents were significantly enhanced. Western blot data showed that the expression of Na+ channels was increased with differentiated-time dependent manner. Single-cell real-time PCR data demonstrated that the expression of Na+ channel mRNA was increased by 21 days of differentiation in NG108-15 cells. More importantly, the mRNA level of Na+ channels in cells with action potential was higher than that in cells without action potential. Differentiation induces expression of voltage-gated Na+ channels and action potential generation in NG108-15 cells. A high level of the Na+ channel density is required for differentiation-triggered action potential generation.

  13. Dispersion of breakdown voltage of liquid helium

    International Nuclear Information System (INIS)

    Ishii, Itaru; Noguchi, Takuya

    1978-01-01

    As for the electrical insulation characteristics of liquid helium, the discrepancy among the measured values by each person is very large even in the fundamental DC breakdown voltage in uniform electric field. The dispersion of experimental values obtained in the experiments by the same person is also large. Hereafter, the difference among the mean values obtained by each experimenter will be referred to as ''deviation of mean values'', and the dispersion of measured values around the mean value obtained by the same person as ''deviation around the man value''. The authors have mainly investigated on the latter experimentally. The cryostat was made of stainless steel, and the innermost helium chamber was of 500 mm I.D. and approximately 1200 mm deep. The high voltage electrode was of brass sphere of 25 mm diameter, and the low voltage electrode was of brass plate. The experiment was conducted for liquid helium boiling at 4.2 K and 1 atm, and the breakdown voltage and time lag were measured by applying the approximately square wave impulses of fast rise and long tail, ramp and DC voltages. The cause of the deviation of mean values may be the presence of impurity particles or the effect of electrode shape. As for the deviation around the mean value, the dispersion is large, and its standard deviation may amount to 10 to 20% of the man value. The dispersion is not due to the statistical time lag, but is due to parameters that vary with breakdown. (Wakatsuki, Y.)

  14. Dynamic characteristics of rotating pretwisted clamped-clamped beam under thermal stress

    International Nuclear Information System (INIS)

    Zhang, Bo; Li, Yueming; Lu, Wei Zhen

    2016-01-01

    Effects of thermal stress on the vibration characteristics, buckling limit and critical speed of a rotating pretwisted beam clamped to rigid hub at a stagger angle were investigated. By considering the work done by thermal stress, the thermal influence on stiffness matrix was introduced in the dynamic model. The motion equations were derived based on Lagrange equation by employing three pure Cartesian deformation variables combined with nonlinear von Karman strain formula. Numerical investigations studied the modal characteristics of the beam. Numerical results calculated from a commercial finite element code and obtained with the present modeling method were in good agreement with the previous results reported in the literature. The combined softening effects due to the thermal stress and the rotation motion were observed. Furthermore, it is shown that the inclusion of thermal stress is necessary for blades operating under a high temperature field. Buckling thermal loads and the critical rotating speed were calculated through solving the corresponding nonlinear equations numerically, and some pertinent conclusions are outlined. It is also found that the peak value position of the first mode shape approaches to the tip of blade with the increment of rotating speed and hub radius. However, the variation in the environment temperature causes only a slight alteration in the mode shape

  15. Dynamic characteristics of rotating pretwisted clamped-clamped beam under thermal stress

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bo; Li, Yueming [State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Key Laboratory of Environment and Control for Flight Vehicle, School of Aerospace, Xi' an Jiaotong UniversityXi' an (China); Lu, Wei Zhen [Dept. of Civil and Architectural Engineering, City University of Hong Kong, Hong Kong (China)

    2016-09-15

    Effects of thermal stress on the vibration characteristics, buckling limit and critical speed of a rotating pretwisted beam clamped to rigid hub at a stagger angle were investigated. By considering the work done by thermal stress, the thermal influence on stiffness matrix was introduced in the dynamic model. The motion equations were derived based on Lagrange equation by employing three pure Cartesian deformation variables combined with nonlinear von Karman strain formula. Numerical investigations studied the modal characteristics of the beam. Numerical results calculated from a commercial finite element code and obtained with the present modeling method were in good agreement with the previous results reported in the literature. The combined softening effects due to the thermal stress and the rotation motion were observed. Furthermore, it is shown that the inclusion of thermal stress is necessary for blades operating under a high temperature field. Buckling thermal loads and the critical rotating speed were calculated through solving the corresponding nonlinear equations numerically, and some pertinent conclusions are outlined. It is also found that the peak value position of the first mode shape approaches to the tip of blade with the increment of rotating speed and hub radius. However, the variation in the environment temperature causes only a slight alteration in the mode shape.

  16. Mechanistic Basis for Type 2 Long QT Syndrome Caused by KCNH2 Mutations that Disrupt Conserved Arginine Residue in the Voltage Sensor

    Science.gov (United States)

    McBride, Christie M.; Smith, Ashley M.; Smith, Jennifer L.; Reloj, Allison R.; Velasco, Ellyn J.; Powell, Jonathan; Elayi, Claude S.; Bartos, Daniel C.; Burgess, Don E.

    2013-01-01

    KCNH2 encodes the Kv11.1 channel, which conducts the rapidly activating delayed rectifier K+ current (IKr) in the heart. KCNH2 mutations cause type 2 long QT syndrome (LQT2), which increases the risk for life-threatening ventricular arrhythmias. LQT2 mutations are predicted to prolong the cardiac action potential (AP) by reducing IKr during repolarization. Kv11.1 contains several conserved basic amino acids in the fourth transmembrane segment (S4) of the voltage sensor that are important for normal channel trafficking and gating. This study sought to determine the mechanism(s) by which LQT2 mutations at conserved arginine residues in S4 (R531Q, R531W or R534L) alter Kv11.1 function. Western blot analyses of HEK293 cells transiently expressing R531Q, R531W or R534L suggested that only R534L inhibited Kv11.1 trafficking. Voltage-clamping experiments showed that R531Q or R531W dramatically altered Kv11.1 current (IKv11.1) activation, inactivation, recovery from inactivation and deactivation. Coexpression of wild type (to mimic the patients’ genotypes) mostly corrected the changes in IKv11.1 activation and inactivation, but deactivation kinetics were still faster. Computational simulations using a human ventricular AP model showed that accelerating deactivation rates was sufficient to prolong the AP, but these effects were minimal compared to simply reducing IKr. These are the first data to demonstrate that coexpressing wild type can correct activation and inactivation dysfunction caused by mutations at a critical voltage-sensing residue in Kv11.1. We conclude that some Kv11.1 mutations might accelerate deactivation to cause LQT2 but that the ventricular AP duration is much more sensitive to mutations that decrease IKr. This likely explains why most LQT2 mutations are nonsense or trafficking-deficient. PMID:23546015

  17. Power conditioning using dynamic voltage restorers under different voltage sag types.

    Science.gov (United States)

    Saeed, Ahmed M; Abdel Aleem, Shady H E; Ibrahim, Ahmed M; Balci, Murat E; El-Zahab, Essam E A

    2016-01-01

    Voltage sags can be symmetrical or unsymmetrical depending on the causes of the sag. At the present time, one of the most common procedures for mitigating voltage sags is by the use of dynamic voltage restorers (DVRs). By definition, a DVR is a controlled voltage source inserted between the network and a sensitive load through a booster transformer injecting voltage into the network in order to correct any disturbance affecting a sensitive load voltage. In this paper, modelling of DVR for voltage correction using MatLab software is presented. The performance of the device under different voltage sag types is described, where the voltage sag types are introduced using the different types of short-circuit faults included in the environment of the MatLab/Simulink package. The robustness of the proposed device is evaluated using the common voltage sag indices, while taking into account voltage and current unbalance percentages, where maintaining the total harmonic distortion percentage of the load voltage within a specified range is desired. Finally, several simulation results are shown in order to highlight that the DVR is capable of effective correction of the voltage sag while minimizing the grid voltage unbalance and distortion, regardless of the fault type.

  18. Evaluation of diel patterns of relative changes in cell turgor of tomato plants using leaf patch clamp pressure probes

    NARCIS (Netherlands)

    Lee, K.M.; Driever, S.M.; Heuvelink, E.; Rüger, S.; Zimmermann, U.; Gelder, de A.; Marcelis, L.F.M.

    2012-01-01

    Relative changes in cell turgor of leaves of well-watered tomato plants were evaluated using the leaf patch clamp pressure probe (LPCP) under dynamic greenhouse climate conditions. Leaf patch clamp pressure changes, a measure for relative changes in cell turgor, were monitored at three different

  19. Targeted Endovascular Temporary Vessel Occlusion with a Reverse Thermosensitive Polymer for Near-Bloodless Partial Nephrectomy: Comparison to Standard Surgical Clamping Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Flacke, Sebastian, E-mail: Sebastian.Flacke@lahey.org [Lahey Clinic, Tuft University Medical School, Department of Radiology (United States); Harty, Niall J.; Laskey, Daniel H.; Moinzadeh, Alireza [Lahey Clinic, Tuft University Medical School, Department of Urology (United States); Benn, James A. [Pluromed Inc (United States); Villani, Rosanna [DaVinci Biomedical Research Products (United States); Kalra, Aarti [Lahey Clinic, Tuft University Medical School, Department of Pathology (United States); Libertino, John A.; Madras, Peter N. [Lahey Clinic, Tuft University Medical School, Department of Urology (United States)

    2012-10-15

    Purpose: To determine whether reversible blood flow interruption to a randomly chosen target region of the kidney may be achieved with the injection of a reverse thermoplastic polymer through an angiographic catheter, thereby facilitating partial nephrectomy without compromising blood flow to the remaining kidney or adding risks beyond those encountered by the use of hilar clamping. Methods: Fifteen pigs underwent partial nephrectomy after blood flow interruption by vascular cross-clamping or injection of polymer (Lumagel Trade-Mark-Sign ) into a segmental artery. Five animals were euthanized after surgery (three open and two laparoscopic resection, cross-clamping n = 2), and 10 (open resection, cross-clamping n = 4) were euthanized after 6 weeks' survival. Blood specimens were obtained periodically, and angiogram and necropsy were performed at 6 weeks. Results: Selective renal ischemia was achieved in all cases. Surgical resection time averaged 9 and 24.5 min in the open and laparoscopic groups, respectively. Estimated blood loss was negligible with the exception of one case where an accessory renal artery was originally overlooked. Reversal of the polymer to a liquid state was consistent angiographically and visually in all cases. Time to complete flow return averaged 7.4 and 2 min for polymer and clamping, respectively. Angiography at 6 weeks revealed no evidence of vascular injury. Laboratory data and necropsies revealed no differences between animals undergoing vascular clamping or polymer injection. Conclusion: Lumagel was as effective as vascular clamping in producing a near bloodless operative field for partial nephrectomy while maintaining flow to the uninvolved portion of the affected kidney.

  20. Solution study of the Escherichia coli DNA polymerase III clamp loader reveals the location of the dynamic ψχ heterodimer

    Directory of Open Access Journals (Sweden)

    Farzaneh Tondnevis

    2015-09-01

    Full Text Available Several X-ray crystal structures of the E. coli core clamp loader containing the five core (δ′, δ, and three truncated γ subunits have been determined, but they lack the ψ and χ subunits. We report the first solution structure of the complete seven-subunit clamp loader complex using small angle X-ray scattering. This structure not only provides information about the location of the χ and ψ subunits but also provides a model of the dynamic nature of the clamp loader complex.

  1. Mitigation of voltage sags in the distribution system with dynamic voltage restorer

    International Nuclear Information System (INIS)

    Viglas, D.; Belan, A.

    2012-01-01

    Dynamic voltage restorer is a custom power device that is used to improve voltage sags or swells in electrical distribution system. The components of the Dynamic Voltage Restorer consist of injection transformers, voltage source inverter, passive filters and energy storage. The main function of the Dynamic voltage restorer is used to inject three phase voltage in series and in synchronism with the grid voltages in order to compensate voltage disturbances. This article deals with mitigation of voltage sags caused by three-phase short circuit. Dynamic voltage restorer is modelled in MATLAB/Simulink. (Authors)

  2. SVPWM Technique with Varying DC-Link Voltage for Common Mode Voltage Reduction in a Matrix Converter and Analytical Estimation of its Output Voltage Distortion

    Science.gov (United States)

    Padhee, Varsha

    converter. This conceivably aids the sizing and design of output passive filters. An analytical estimation method has been presented to achieve this purpose for am IMC. Knowledge of the fundamental component in output voltage can be utilized to calculate its Total Harmonic Distortion (THD). The effectiveness of the proposed SVPWM algorithms and the analytical estimation technique is substantiated by simulations in MATLAB / Simulink and experiments on a laboratory prototype of the IMC. Proper comparison plots have been provided to contrast the performance of the proposed methods with the conventional SVPWM method. The behavior of output voltage distortion and CMV with variation in operating parameters like modulation index and output frequency has also been analyzed.

  3. Adjustable static and dynamic actuation of clamped-guided beams using electrothermal axial loads

    KAUST Repository

    Alcheikh, Nouha

    2018-02-14

    The paper presents adjustable static and dynamic actuations of in-plane clamped-guided beams. The structures, of variable stiffness, can be used as highly tunable resonators and actuators. Axial loads are applied through electrothermal U-shaped and flexure beams actuators stacked near the edges of curved (arch) beams. The electrothermal actuators can be configurred in various ways to adjust as desired the mechanical stiffness of the structures; thereby controlling their deformation stroke as actuators and their operating resonance frequency as resonators. The experimental and finite element results demonstrate the flexibility of the designs in terms of static displacements and resonance frequencies of the first and second symmetric modes of the arches. The results show considerable increase in the resonance frequency and deflection of the microbeam upon changing end actuation conditions, which can be promising for low voltage actuation and tunable resonators applications, such as filters and memory devices. As case studies of potential device configurations of the proposed design, we demonstrate eight possibilities of achieving new static and dynamic behaviors, which produce various resonance frequencies and static displacement curves. The ability to actively shift the entire frequency response curve of a device is desirable for several applications to compensate for in-use anchor degradations and deformations. As an example, we experimentally demonstrate using the device as a resonant logic gate, with active resonance tuning, showing fundamental 2-bit logic functions, such as AND,XOR, and NOR.

  4. Adjustable static and dynamic actuation of clamped-guided beams using electrothermal axial loads

    KAUST Repository

    Alcheikh, Nouha; Tella, Sherif Adekunle; Younis, Mohammad I.

    2018-01-01

    The paper presents adjustable static and dynamic actuations of in-plane clamped-guided beams. The structures, of variable stiffness, can be used as highly tunable resonators and actuators. Axial loads are applied through electrothermal U-shaped and flexure beams actuators stacked near the edges of curved (arch) beams. The electrothermal actuators can be configurred in various ways to adjust as desired the mechanical stiffness of the structures; thereby controlling their deformation stroke as actuators and their operating resonance frequency as resonators. The experimental and finite element results demonstrate the flexibility of the designs in terms of static displacements and resonance frequencies of the first and second symmetric modes of the arches. The results show considerable increase in the resonance frequency and deflection of the microbeam upon changing end actuation conditions, which can be promising for low voltage actuation and tunable resonators applications, such as filters and memory devices. As case studies of potential device configurations of the proposed design, we demonstrate eight possibilities of achieving new static and dynamic behaviors, which produce various resonance frequencies and static displacement curves. The ability to actively shift the entire frequency response curve of a device is desirable for several applications to compensate for in-use anchor degradations and deformations. As an example, we experimentally demonstrate using the device as a resonant logic gate, with active resonance tuning, showing fundamental 2-bit logic functions, such as AND,XOR, and NOR.

  5. Diuretic response to acute hypertension is blunted during angiotensin II clamp

    DEFF Research Database (Denmark)

    Leong, Patrick K K; Zhang, Yibin; Yang, Li E

    2002-01-01

    and endogenous lithium clearance increased two- and threefold, respectively. We conclude that HOE-140, an inhibitor of the B(2) receptor, potentiates the sensitivity of arterial pressure to ANG II and that clamping systemic ANG II levels during acute hypertension blunts the magnitude of the pressure diuretic...

  6. Surge Protection in Low-Voltage AC Power Circuits: An Anthology

    Science.gov (United States)

    Martzloff, F. D.

    2002-10-01

    The papers included in this part of the Anthology provide basic information on the propagation of surges in low-voltage AC power circuits. The subject was approached by a combination of experiments and theoretical considerations. One important distinction is made between voltage surges and current surges. Historically, voltage surges were the initial concern. After the introduction and widespread use of current-diverting surge-protective devices at the point-of-use, the propagation of current surges became a significant factor. The papers included in this part reflect this dual dichotomy of voltage versus current and impedance mismatch effects versus simple circuit theory.

  7. Voltage regulating circuit

    NARCIS (Netherlands)

    2005-01-01

    A voltage regulating circuit comprising a rectifier (2) for receiving an AC voltage (Vmains) and for generating a rectified AC voltage (vrec), and a capacitor (3) connected in parallel with said rectified AC voltage for providing a DC voltage (VDC) over a load (5), characterized by a unidirectional

  8. Impedance spectra of patch clamp scenarios for single cells immobilized on a lab-on-a-chip

    DEFF Research Database (Denmark)

    Alberti, Massimo; Snakenborg, Detlef; Lopacinska, Joanna M.

    2014-01-01

    and simulated impedance spectra proved that the presented method could distinguish between a cell-attached mode and a whole-cell mode even with low-quality seals. In physiological conditions, the capacitance of HeLa cells was measured to *38 pF. The first gigaseal was recorded and maintained for 40 min. Once...... membrane. After incubating the chip for 24 h, HeLa cells adhered and grew on the chip surface but did not survive when trapped on the microapertures. The microfluidic system proved to work as a micro electrophysiological analysis system, and the IS-based method can be used for further studies on the post......A simple method based on impedance spectroscopy (IS) was developed to distinguish between different patch clamp modes for single cells trapped on microapertures in a patch clamp microchannel array designed for patch clamping on cultured cells. The method allows detecting via impedance analysis...

  9. Stimulation of Na+-alanine cotransport activates a voltage-dependent conductance in single proximal tubule cells isolated from frog kidney

    Science.gov (United States)

    Robson, L; Hunter, M

    1999-01-01

    The swelling induced by Na+-alanine cotransport in proximal tubule cells of the frog kidney is followed by regulatory volume decrease (RVD). This RVD is inhibited by gadolinium (Gd3+), an inhibitor of stretch-activated channels, but is independent of extracellular Ca2+. In this study, the whole cell patch clamp technique was utilized to examine the effect of Na+-alanine cotransport on two previously identified volume- and Gd3+-sensitive conductances. One conductance is voltage dependent and anion selective (GVD) whilst the other is voltage independent and cation selective (GVI). Addition of 5 mM L-alanine to the bathing solution increased the whole cell conductance and gave a positive (depolarizing) shift in the reversal potential (Vrev, equivalent to the membrane potential in current-clamped cells) consistent with activation of Na+-alanine cotransport. Vrev shifted from -36 ± 4·9 to +12·9 ± 4·2 mV (n= 15). In the presence of alanine, the total whole cell conductance had several components including the cotransporter conductance and GVD and GVI. These conductances were separated using Gd3+, which inhibits both GVD and GVI, and the time dependency of GVD. Of these two volume-sensitive conductances, L-alanine elicited a specific increase in GVD, whereas GVI was unaffected. The L-alanine-induced activation of GVD was significantly reduced when cells were incubated in a hypertonic bathing solution. In summary, in single proximal tubule cells isolated from frog kidney, on stimulation of Na+-alanine cotransport GVD is activated, while GVI is unaffected. Taken with other evidence, this suggests that GVD is activated by cell swelling, consequent upon alanine entry, and may play a role as an anion efflux pathway during alanine-induced volume regulation. PMID:10226159

  10. Laser microsurgery of higher plant cell walls permits patch-clamp access

    International Nuclear Information System (INIS)

    Henriksen, G.H.; Taylor, A.R.; Brownlee, C.; Assmann, S.M.

    1996-01-01

    Plasma membranes of guard cells in epidermal peels of Vicia faba and Commelina communis can be made accessible to a patch-clamp pipet by removing a small portion (1-3 micrometer in diameter) of the guard cell wall using a microbeam of ultraviolet light generated by a nitrogen laser. Using this laser microsurgical technique, we have measured channel activity across plasma membranes of V. faba guard cells in both cell-attached and isolated patch configurations. Measurements made in the inside-out patch configuration revealed two distinct K+-selective channels. Major advantages of the laser microsurgical technique include the avoidance of enzymatic protoplast isolation, the ability to study cell types that have been difficult to isolate as protoplasts or for which enzymatic isolation protocols result in protoplasts not amenable to patch-clamp studies, the maintenance of positional information in single-channel measurements, reduced disruption of cell-wall-mediated signaling pathways, and the ability to investigate intercellular signaling through studies of cells remaining situated within tissue

  11. Hysteresis analysis of graphene transistor under repeated test and gate voltage stress

    International Nuclear Information System (INIS)

    Yang Jie; Jia Kunpeng; Su Yajuan; Zhao Chao; Chen Yang

    2014-01-01

    The current transport characteristic is studied systematically based on a back-gate graphene field effect transistor, under repeated test and gate voltage stress. The interface trapped charges caused by the gate voltage sweep process screens the gate electric field, and results in the neutral point voltage shift between the forth and back sweep direction. In the repeated test process, the neutral point voltage keeps increasing with test times in both forth and back sweeps, which indicates the existence of interface trapped electrons residual and accumulation. In gate voltage stress experiment, the relative neutral point voltage significantly decreases with the reducing of stress voltage, especially in −40 V, which illustrates the driven-out phenomenon of trapped electrons under negative voltage stress. (semiconductor devices)

  12. Scorpion β-toxin interference with NaV channel voltage sensor gives rise to excitatory and depressant modes

    Science.gov (United States)

    Leipold, Enrico; Borges, Adolfo

    2012-01-01

    Scorpion β toxins, peptides of ∼70 residues, specifically target voltage-gated sodium (NaV) channels to cause use-dependent subthreshold channel openings via a voltage–sensor trapping mechanism. This excitatory action is often overlaid by a not yet understood depressant mode in which NaV channel activity is inhibited. Here, we analyzed these two modes of gating modification by β-toxin Tz1 from Tityus zulianus on heterologously expressed NaV1.4 and NaV1.5 channels using the whole cell patch-clamp method. Tz1 facilitated the opening of NaV1.4 in a use-dependent manner and inhibited channel opening with a reversed use dependence. In contrast, the opening of NaV1.5 was exclusively inhibited without noticeable use dependence. Using chimeras of NaV1.4 and NaV1.5 channels, we demonstrated that gating modification by Tz1 depends on the specific structure of the voltage sensor in domain 2. Although residue G658 in NaV1.4 promotes the use-dependent transitions between Tz1 modification phenotypes, the equivalent residue in NaV1.5, N803, abolishes them. Gating charge neutralizations in the NaV1.4 domain 2 voltage sensor identified arginine residues at positions 663 and 669 as crucial for the outward and inward movement of this sensor, respectively. Our data support a model in which Tz1 can stabilize two conformations of the domain 2 voltage sensor: a preactivated outward position leading to NaV channels that open at subthreshold potentials, and a deactivated inward position preventing channels from opening. The results are best explained by a two-state voltage–sensor trapping model in that bound scorpion β toxin slows the activation as well as the deactivation kinetics of the voltage sensor in domain 2. PMID:22450487

  13. Mechanism of formation of subnanosecond current front in high-voltage pulse open discharge

    Science.gov (United States)

    Schweigert, I. V.; Alexandrov, A. L.; Zakrevsky, Dm. E.; Bokhan, P. A.

    2014-11-01

    The mechanism of subnanosecond current front rise observed previously in the experiment in high-voltage pulse open discharge in helium is studied in kinetic particle-in-cell simulations. The Boltzmann equations for electrons, ions, and fast atoms are solved self-consistently with the Poisson equations for the electrical potential. The partial contributions to the secondary electron emission from the ions, fast atoms, photons, and electrons, bombarding the electrode, are calculated. In simulations, as in the experiment, the discharge glows between two symmetrical cathodes and the anode grid in the midplane at P =6 Torr and the applied voltage of 20 kV. The electron avalanche development is considered for two experimental situations during the last stage of breakdown: (i) with constant voltage and (ii) with decreasing voltage. For case (i), the subnanosecond current front rise is set by photons from the collisional excitation transfer reactions. For the case (ii), the energetic electrons swamp the cathode during voltage drop and provide the secondary electron emission for the subnanosecond current rise, observed in the experiment.

  14. IBM-PC based high voltage controller [Paper No.: L7

    International Nuclear Information System (INIS)

    Mondal, N.K.; Kalmani, S.D.

    1993-01-01

    A simple IBM-PC/XT based high voltage controller is designed for C.A.E.N. high voltage supply unit, which is being used for testing the prototype detector for future accelerator experiment. The high voltage output of the supply unit can be remotely programmed. The V-set Lemo connectors at the rear panel provides the remote control facility. Similarly V-mon and I-mon can be used for remotely monitoring the voltage set and the current drawn from the supply unit. The controller described here sets the high voltage through V-set and monitors the voltage set, through V-mon at a pre-determined time interval. The monitoring is a background job and is done as an interrupt service routine of IRQ3. A simple menu driven software package used is written in Q-Basic and MASM. (author). 1 fig

  15. Voltage-carrying states in superconducting microstrips

    International Nuclear Information System (INIS)

    Stuivinga, M.E.C.

    1983-01-01

    When the critical current is exceeded in a superconducting microstrip, voltage-carrying states with a resistance significantly below the normal state resistance can occur. Phase-slip centers (PSC) appear at about the critical temperature. These are successive local voltage units which manifest themselves as strip-like increments in voltage in the I-V characteristic. For temperatures off the critical temperature the PSC regime degenerates into a region of normal material, a so-called hot spot. These two phenomena, PSC and hot spots, form the subject of this thesis. To gain a better understanding of the phase-slip center process, an experiment was designed to measure local values of the quasi-particle and pair potential. The results of local potential and gap measurements at a PSC in aluminium are presented and discussed. Special attention is paid to pair-breaking interactions which can shorten the relaxation time. A non-linear differential equation is derived which describes the development of a PSC into a normal hot spot under the influence of Joule heating. It incorporates the temperature rise due to the dissipative processes occurring in the charge imbalance tails. Numerical solutions are presented for a set of parameters, including those for aluminium and tin. Subsequently, they are compared with experiments. (Auth.)

  16. High-voltage test and measuring techniques

    CERN Document Server

    Hauschild, Wolfgang

    2014-01-01

    It is the intent of this book to combine high-voltage (HV) engineering with HV testing technique and HV measuring technique. Based on long-term experience gained by the authors as lecturer and researcher as well as member in international organizations, such as IEC and CIGRE, the book will reflect the state of the art as well as the future trends in testing and diagnostics of HV equipment to ensure a reliable generation, transmission and distribution of electrical energy. The book is intended not only for experts but also for students in electrical engineering and high-voltage engineering.

  17. A comparison between the minimal model and the glucose clamp in the assessment of insulin sensitivity across the spectrum of glucose tolerance. Insulin Resistance Atherosclerosis Study.

    Science.gov (United States)

    Saad, M F; Anderson, R L; Laws, A; Watanabe, R M; Kades, W W; Chen, Y D; Sands, R E; Pei, D; Savage, P J; Bergman, R N

    1994-09-01

    An insulin-modified frequently sampled intravenous glucose tolerance test (FSIGTT) with minimal model analysis was compared with the glucose clamp in 11 subjects with normal glucose tolerance (NGT), 20 with impaired glucose tolerance (IGT), and 24 with non-insulin-dependent diabetes mellitus (NIDDM). The insulin sensitivity index (SI) was calculated from FSIGTT using 22- and 12-sample protocols (SI(22) and SI(12), respectively). Insulin sensitivity from the clamp was expressed as SI(clamp) and SIP(clamp). Minimal model parameters were similar when calculated with SI(22) and SI(12). SI could not be distinguished from 0 in approximately 50% of diabetic patients with either protocol. SI(22) correlated significantly with SI(clamp) in the whole group (r = 0.62), and in the NGT (r = 0.53), IGT (r = 0.48), and NIDDM (r = 0.41) groups (P SIP(clamp) were expressed in the same units, SI(22) was 66 +/- 5% (mean +/- SE) and 50 +/- 8% lower than SI(clamp) and SIP(clamp), respectively. Thus, minimal model analysis of the insulin-modified FSIGTT provides estimates of insulin sensitivity that correlate significantly with those from the glucose clamp. The correlation was weaker, however, in NIDDM. The insulin-modified FSIGTT can be used as a simple test for assessment of insulin sensitivity in population studies involving nondiabetic subjects. Additional studies are needed before using this test routinely in patients with NIDDM.

  18. Design of a Rad-Hard eFuse Trimming Circuit for Bandgap Voltage Reference for LHC Experiments Upgrades

    CERN Document Server

    Besirli, Mustafa; Koukab, Adil; Michelis, Stefano

    A precise and stable reference voltage is required to generate a stable output voltage in DC/DC converters. This reference voltage must be independent of temperature, power supply, radiation, intrinsic technology mismatch and process variation. This master's thesis reports the development of a rad-hard bandgap voltage reference with electrical fuse (eFuse) based analog calibration circuit in a commercial 130nm technology. According to the test results, the maximum error in the bandgap voltage (300mV in this application) was reduced from ±30mV to less than ±0.6mV thanks to the eFuse trimming. A temperature, power supply, radiation, mismatch and process-independent reference voltage was generated to provide reference voltage to first (bPOL12V) and second (bPOL2V5) stage DC/DC converters. This circuit will be integrated in bPOL12V and bPOL2V5 converters for high-luminosity LHC upgrades.

  19. Commissioning experiences on high voltage generator of 750 KeV DC accelerator at RRCAT, Indore

    International Nuclear Information System (INIS)

    Banwari, R.; Kasliwal, A.; Pandit, T.G.

    2009-01-01

    Design approach of high voltage generator for 750 keV DC accelerator, developed at RRCAT Indore, inculcates a unique feature of high frequency operation of symmetrical Cockcroft-Walton voltage generator. Apart from design simplicity and feasibility of modular construction, the high frequency use of symmetrical Cockcroft-Walton circuit gives added advantages of less ripple, better regulation, faster response and low stored energy in the system. Additionally the scheme allows us the use of low voltage, light weight components thus improving the overall economy of the system. The accelerator has been commissioned and made operational at its rated energy of 750 keV in the recent past. With brief introduction on design aspects of high voltage generator and filament power supply of this accelerator, the paper presented here describes the developmental steps of various components with focus on challenges encountered and solutions implemented. Development of high frequency inverter, high voltage ferrite core transformer, compensating inductors, interface bushings, voltage multiplier stack, and filament transformer along with floating power supply for electron emitter of the accelerator has been dealt in detail. The failures encountered during commissioning stages of the accelerator have been reported with measures taken for improvement of the specific components. Intricacies of the reflected capacitance of the multiplier stack and arc-current ground return are also described with their effects on system operation and reliability. (author)

  20. Voltage-sensing domain mode shift is coupled to the activation gate by the N-terminal tail of hERG channels.

    Science.gov (United States)

    Tan, Peter S; Perry, Matthew D; Ng, Chai Ann; Vandenberg, Jamie I; Hill, Adam P

    2012-09-01

    Human ether-a-go-go-related gene (hERG) potassium channels exhibit unique gating kinetics characterized by unusually slow activation and deactivation. The N terminus of the channel, which contains an amphipathic helix and an unstructured tail, has been shown to be involved in regulation of this slow deactivation. However, the mechanism of how this occurs and the connection between voltage-sensing domain (VSD) return and closing of the gate are unclear. To examine this relationship, we have used voltage-clamp fluorometry to simultaneously measure VSD motion and gate closure in N-terminally truncated constructs. We report that mode shifting of the hERG VSD results in a corresponding shift in the voltage-dependent equilibrium of channel closing and that at negative potentials, coupling of the mode-shifted VSD to the gate defines the rate of channel closure. Deletion of the first 25 aa from the N terminus of hERG does not alter mode shifting of the VSD but uncouples the shift from closure of the cytoplasmic gate. Based on these observations, we propose the N-terminal tail as an adaptor that couples voltage sensor return to gate closure to define slow deactivation gating in hERG channels. Furthermore, because the mode shift occurs on a time scale relevant to the cardiac action potential, we suggest a physiological role for this phenomenon in maximizing current flow through hERG channels during repolarization.

  1. New force replica exchange method and protein folding pathways probed by force-clamp technique.

    Science.gov (United States)

    Kouza, Maksim; Hu, Chin-Kun; Li, Mai Suan

    2008-01-28

    We have developed a new extended replica exchange method to study thermodynamics of a system in the presence of external force. Our idea is based on the exchange between different force replicas to accelerate the equilibrium process. This new approach was applied to obtain the force-temperature phase diagram and other thermodynamical quantities of the three-domain ubiquitin. Using the C(alpha)-Go model and the Langevin dynamics, we have shown that the refolding pathways of single ubiquitin depend on which terminus is fixed. If the N end is fixed then the folding pathways are different compared to the case when both termini are free, but fixing the C terminal does not change them. Surprisingly, we have found that the anchoring terminal does not affect the pathways of individual secondary structures of three-domain ubiquitin, indicating the important role of the multidomain construction. Therefore, force-clamp experiments, in which one end of a protein is kept fixed, can probe the refolding pathways of a single free-end ubiquitin if one uses either the polyubiquitin or a single domain with the C terminus anchored. However, it is shown that anchoring one end does not affect refolding pathways of the titin domain I27, and the force-clamp spectroscopy is always capable to predict folding sequencing of this protein. We have obtained the reasonable estimate for unfolding barrier of ubiquitin, using the microscopic theory for the dependence of unfolding time on the external force. The linkage between residue Lys48 and the C terminal of ubiquitin is found to have the dramatic effect on the location of the transition state along the end-to-end distance reaction coordinate, but the multidomain construction leaves the transition state almost unchanged. We have found that the maximum force in the force-extension profile from constant velocity force pulling simulations depends on temperature nonlinearly. However, for some narrow temperature interval this dependence becomes

  2. Screening of E. coli β-clamp Inhibitors Revealed that Few Inhibit Helicobacter pylori More Effectively: Structural and Functional Characterization

    Directory of Open Access Journals (Sweden)

    Preeti Pandey

    2018-01-01

    Full Text Available The characteristic of interaction with various enzymes and processivity-promoting nature during DNA replication makes β-clamp an important drug target. Helicobacter pylori (H. pylori have several unique features in DNA replication machinery that makes it different from other microorganisms. To find out whether difference in DNA replication proteins behavior accounts for any difference in drug response when compared to E. coli, in the present study, we have tested E. coli β-clamp inhibitor molecules against H. pylori β-clamp. Various approaches were used to test the binding of inhibitors to H. pylori β-clamp including docking, surface competition assay, complex structure determination, as well as antimicrobial assay. Out of five shortlisted inhibitor molecules on the basis of docking score, three molecules, 5-chloroisatin, carprofen, and 3,4-difluorobenzamide were co-crystallized with H. pylori β-clamp and the structures show that they bind at the protein-protein interaction site as expected. In vivo studies showed only two molecules, 5-chloroisatin, and 3,4-difluorobenzamide inhibited the growth of the pylori with MIC values in micro molar range, which is better than the inhibitory effect of the same drugs on E. coli. Therefore, the evaluation of such drugs against H. pylori may explore the possibility to use to generate species-specific pharmacophore for development of new drugs against H. pylori.

  3. Screening of E. coli β-clamp Inhibitors Revealed that Few Inhibit Helicobacter pylori More Effectively: Structural and Functional Characterization.

    Science.gov (United States)

    Pandey, Preeti; Verma, Vijay; Dhar, Suman Kumar; Gourinath, Samudrala

    2018-01-11

    The characteristic of interaction with various enzymes and processivity-promoting nature during DNA replication makes β-clamp an important drug target. Helicobacter pylori ( H. pylori ) have several unique features in DNA replication machinery that makes it different from other microorganisms. To find out whether difference in DNA replication proteins behavior accounts for any difference in drug response when compared to E. coli , in the present study, we have tested E. coli β-clamp inhibitor molecules against H. pylori β-clamp. Various approaches were used to test the binding of inhibitors to H. pylori β-clamp including docking, surface competition assay, complex structure determination, as well as antimicrobial assay. Out of five shortlisted inhibitor molecules on the basis of docking score, three molecules, 5-chloroisatin, carprofen, and 3,4-difluorobenzamide were co-crystallized with H. pylori β-clamp and the structures show that they bind at the protein-protein interaction site as expected. In vivo studies showed only two molecules, 5-chloroisatin, and 3,4-difluorobenzamide inhibited the growth of the pylori with MIC values in micro molar range, which is better than the inhibitory effect of the same drugs on E. coli . Therefore, the evaluation of such drugs against H. pylori may explore the possibility to use to generate species-specific pharmacophore for development of new drugs against H. pylori .

  4. Investigating the effect of clamping force on the fatigue life of bolted plates using volumetric approach

    International Nuclear Information System (INIS)

    Esmaeili, F.; Chakherlou, T. N.; Zehsaz, M.; Hasanifard, S.

    2013-01-01

    In this paper, the effects of bolt clamping force on the fatigue life for bolted plates made from Al7075-T6 have been studied on the values of notch strength reduction factor obtained by volumetric approach. To attain stress distribution around the notch (hole) which is required for volumetric approach, nonlinear finite element simulations were carried out. To estimate the fatigue life, the available smooth S-N curve of Al7075-T6 and the notch strength reduction factor obtained from volumetric method were used. The estimated fatigue life was compared with the available experimental test results. The investigation shows that there is a good agreement between the life predicted by the volumetric approach and the experimental results for various specimens with different amount of clamping forces. Volumetric approach and experimental results showed that the fatigue life of bolted plates improves because of the compressive stresses created around the plate hole due to clamping force.

  5. Characterization of a patch-clamp microchannel array towards neuronal networks analysis

    DEFF Research Database (Denmark)

    Alberti, Massimo; Snakenborg, Detlef; Lopacinska, Joanna M.

    2010-01-01

    for simultaneous patch clamping of cultured cells or neurons in the same network. A disposable silicon/silicon dioxide (Si/SiO2) chip with a microhole array was integrated in a microfluidic system for cell handling, perfusion and electrical recording. Fluidic characterization showed that our PC mu CA can work...

  6. Beyond voltage-gated ion channels: Voltage-operated membrane proteins and cellular processes.

    Science.gov (United States)

    Zhang, Jianping; Chen, Xingjuan; Xue, Yucong; Gamper, Nikita; Zhang, Xuan

    2018-04-18

    Voltage-gated ion channels were believed to be the only voltage-sensitive proteins in excitable (and some non-excitable) cells for a long time. Emerging evidence indicates that the voltage-operated model is shared by some other transmembrane proteins expressed in both excitable and non-excitable cells. In this review, we summarize current knowledge about voltage-operated proteins, which are not classic voltage-gated ion channels as well as the voltage-dependent processes in cells for which single voltage-sensitive proteins have yet to be identified. Particularly, we will focus on the following. (1) Voltage-sensitive phosphoinositide phosphatases (VSP) with four transmembrane segments homologous to the voltage sensor domain (VSD) of voltage-gated ion channels; VSPs are the first family of proteins, other than the voltage-gated ion channels, for which there is sufficient evidence for the existence of the VSD domain; (2) Voltage-gated proton channels comprising of a single voltage-sensing domain and lacking an identified pore domain; (3) G protein coupled receptors (GPCRs) that mediate the depolarization-evoked potentiation of Ca 2+ mobilization; (4) Plasma membrane (PM) depolarization-induced but Ca 2+ -independent exocytosis in neurons. (5) Voltage-dependent metabolism of phosphatidylinositol 4,5-bisphosphate (PtdIns[4,5]P 2 , PIP 2 ) in the PM. These recent discoveries expand our understanding of voltage-operated processes within cellular membranes. © 2018 Wiley Periodicals, Inc.

  7. A single Markov-type kinetic model accounting for the macroscopic currents of all human voltage-gated sodium channel isoforms.

    Science.gov (United States)

    Balbi, Pietro; Massobrio, Paolo; Hellgren Kotaleski, Jeanette

    2017-09-01

    Modelling ionic channels represents a fundamental step towards developing biologically detailed neuron models. Until recently, the voltage-gated ion channels have been mainly modelled according to the formalism introduced by the seminal works of Hodgkin and Huxley (HH). However, following the continuing achievements in the biophysical and molecular comprehension of these pore-forming transmembrane proteins, the HH formalism turned out to carry limitations and inconsistencies in reproducing the ion-channels electrophysiological behaviour. At the same time, Markov-type kinetic models have been increasingly proven to successfully replicate both the electrophysiological and biophysical features of different ion channels. However, in order to model even the finest non-conducting molecular conformational change, they are often equipped with a considerable number of states and related transitions, which make them computationally heavy and less suitable for implementation in conductance-based neurons and large networks of those. In this purely modelling study we develop a Markov-type kinetic model for all human voltage-gated sodium channels (VGSCs). The model framework is detailed, unifying (i.e., it accounts for all ion-channel isoforms) and computationally efficient (i.e. with a minimal set of states and transitions). The electrophysiological data to be modelled are gathered from previously published studies on whole-cell patch-clamp experiments in mammalian cell lines heterologously expressing the human VGSC subtypes (from NaV1.1 to NaV1.9). By adopting a minimum sequence of states, and using the same state diagram for all the distinct isoforms, the model ensures the lightest computational load when used in neuron models and neural networks of increasing complexity. The transitions between the states are described by original ordinary differential equations, which represent the rate of the state transitions as a function of voltage (i.e., membrane potential). The

  8. Stray voltage mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Jamali, B.; Piercy, R.; Dick, P. [Kinetrics Inc., Toronto, ON (Canada). Transmission and Distribution Technologies

    2008-04-09

    This report discussed issues related to farm stray voltage and evaluated mitigation strategies and costs for limiting voltage to farms. A 3-phase, 3-wire system with no neutral ground was used throughout North America before the 1930s. Transformers were connected phase to phase without any electrical connection between the primary and secondary sides of the transformers. Distribution voltage levels were then increased and multi-grounded neutral wires were added. The earth now forms a parallel return path for the neutral current that allows part of the neutral current to flow continuously through the earth. The arrangement is responsible for causing stray voltage. Stray voltage causes uneven milk production, increased incidences of mastitis, and can create a reluctance to drink water amongst cows when stray voltages are present. Off-farm sources of stray voltage include phase unbalances, undersized neutral wire, and high resistance splices on the neutral wire. Mitigation strategies for reducing stray voltage include phase balancing; conversion from single to 3-phase; increasing distribution voltage levels, and changing pole configurations. 22 refs., 5 tabs., 13 figs.

  9. LRRK2 regulates voltage-gated calcium channel function.

    Directory of Open Access Journals (Sweden)

    Cade eBedford

    2016-05-01

    Full Text Available Voltage-gated Ca2+ (CaV channels enable Ca2+ influx in response to membrane depolarization. CaV2.1 channels are localized to the presynaptic membrane of many types of neurons where they are involved in triggering neurotransmitter release. Several signaling proteins have been identified as important CaV2.1 regulators including protein kinases, G-proteins and Ca2+ binding proteins. Recently, we discovered that leucine rich repeat kinase 2 (LRRK2, a protein associated with inherited Parkinson’s disease, interacts with specific synaptic proteins and influences synaptic transmission. Since synaptic proteins functionally interact with CaV2.1 channels and synaptic transmission is triggered by Ca2+ entry via CaV2.1, we investigated whether LRRK2 could impact CaV2.1 channel function. CaV2.1 channel properties were measured using whole cell patch clamp electrophysiology in HEK293 cells transfected with CaV2.1 subunits and various LRRK2 constructs. Our results demonstrate that both wild type LRRK2 and the G2019S LRRK2 mutant caused a significant increase in whole cell Ca2+ current density compared to cells expressing only the CaV2.1 channel complex. In addition, LRRK2 expression caused a significant hyperpolarizing shift in voltage-dependent activation while having no significant effect on inactivation properties. These functional changes in CaV2.1 activity are likely due to a direct action of LRRK2 as we detected a physical interaction between LRRK2 and the β3 CaV channel subunit via coimmunoprecipitation. Furthermore, effects on CaV2.1 channel function are dependent on LRRK2 kinase activity as these could be reversed via treatment with a LRRK2 inhibitor. Interestingly, LRRK2 also augmented endogenous voltage-gated Ca2+ channel function in PC12 cells suggesting other CaV channels could also be regulated by LRRK2. Overall, our findings support a novel physiological role for LRRK2 in regulating CaV2.1 function that could have implications for how

  10. Imaging Voltage in Genetically Defined Neuronal Subpopulations with a Cre Recombinase-Targeted Hybrid Voltage Sensor.

    Science.gov (United States)

    Bayguinov, Peter O; Ma, Yihe; Gao, Yu; Zhao, Xinyu; Jackson, Meyer B

    2017-09-20

    Genetically encoded voltage indicators create an opportunity to monitor electrical activity in defined sets of neurons as they participate in the complex patterns of coordinated electrical activity that underlie nervous system function. Taking full advantage of genetically encoded voltage indicators requires a generalized strategy for targeting the probe to genetically defined populations of cells. To this end, we have generated a mouse line with an optimized hybrid voltage sensor (hVOS) probe within a locus designed for efficient Cre recombinase-dependent expression. Crossing this mouse with Cre drivers generated double transgenics expressing hVOS probe in GABAergic, parvalbumin, and calretinin interneurons, as well as hilar mossy cells, new adult-born neurons, and recently active neurons. In each case, imaging in brain slices from male or female animals revealed electrically evoked optical signals from multiple individual neurons in single trials. These imaging experiments revealed action potentials, dynamic aspects of dendritic integration, and trial-to-trial fluctuations in response latency. The rapid time response of hVOS imaging revealed action potentials with high temporal fidelity, and enabled accurate measurements of spike half-widths characteristic of each cell type. Simultaneous recording of rapid voltage changes in multiple neurons with a common genetic signature offers a powerful approach to the study of neural circuit function and the investigation of how neural networks encode, process, and store information. SIGNIFICANCE STATEMENT Genetically encoded voltage indicators hold great promise in the study of neural circuitry, but realizing their full potential depends on targeting the sensor to distinct cell types. Here we present a new mouse line that expresses a hybrid optical voltage sensor under the control of Cre recombinase. Crossing this line with Cre drivers generated double-transgenic mice, which express this sensor in targeted cell types. In

  11. Gain-clamping techniques in two-stage double-pass L-band EDFA

    Indian Academy of Sciences (India)

    Two designs of long-wavelength band erbium-doped fiber amplifier (L-band. EDFA) for gain clamping in double-pass systems are demonstrated and compared. The first design is based on ring laser technique where a backward amplified spontaneous emis- sion (ASE) from the second stage is routed into the feedback loop ...

  12. Co-wound voltage sensor R ampersand D for TPX magnets

    International Nuclear Information System (INIS)

    Chaplin, M.R.; Martovetsky, N.N.; Zbasnik, J.

    1995-01-01

    The Tokamak Physics Experiment (TPX) will be the first tokamak to use superconducting cable-in-conduit-conductors (CICC) in all Poloidal Field (PF) ampersand Toroidal Field (TF) magnets. Conventional quench detection, the measurement of small resistive normal-zone voltages ( 4 kV). In the quench detection design for TPX, we have considered several different locations for internal co-wound voltage sensors in the cable cross-section as the primary mechanism to cancel this inductive noise. The Noise Rejection Experiment (NRE) at LLNL and the Noise Injection Experiment (NIE) at MIT have been designed to evaluate which internal locations will produce the best inductive-noise cancellation, and provide us with experimental data to calibrate analysis codes. The details of the experiments and resulting data are presented

  13. Analysis of the Pallet Clamping Conditions in Work Positioning

    OpenAIRE

    L. A. Kolesnikov

    2016-01-01

    Pallets of automatic transfer lines serve as the technological and work-transfer equipment. However, their design is based on the general principles of designing machine accessories. Calculation of the basic design parameters of work based on their functioning features is fairly relevant.In pallet transfer movement over work positioning there is a mismatch between axes of the basic bushing of a pallet and the clamping locks of positioning. The paper identifies the factors influencing it, and ...

  14. The Piezo Actuator-Driven Pulsed Water Jet System for Minimizing Renal Damage after Off-Clamp Laparoscopic Partial Nephrectomy.

    Science.gov (United States)

    Kamiyama, Yoshihiro; Yamashita, Shinichi; Nakagawa, Atsuhiro; Fujii, Shinji; Mitsuzuka, Koji; Kaiho, Yasuhiro; Ito, Akihiro; Abe, Takaaki; Tominaga, Teiji; Arai, Yoichi

    2017-09-01

    In the setting of partial nephrectomy (PN) for renal cell carcinoma, postoperative renal dysfunction might be caused by surgical procedure. The aim of this study was to clarify the technical safety and renal damage after off-clamp laparoscopic PN (LPN) with a piezo actuator-driven pulsed water jet (ADPJ) system. Eight swine underwent off-clamp LPN with this surgical device, while off-clamp open PN was also performed with radio knife or soft coagulation. The length of the removed kidney was 40 mm, and the renal parenchyma was dissected until the renal calyx became clearly visible. The degree of renal degeneration from the resection surface was compared by Hematoxylin-Eosin staining and immunostaining for 1-methyladenosine, a sensitive marker for the ischemic tissue damage. The mRNA levels of neutrophil gelatinase-associated lipocalin (Ngal), a biomarker for acute kidney injury, were measured by quantitative real-time PCR. Off-clamp LPN with ADPJ system was successfully performed while preserving fine blood vessels and the renal calix with little bleeding. In contrast to other devices, the resection surface obtained with the ADPJ system showed only marginal degree of ischemic changes. Indeed, the expression level of Ngal mRNA was lower in the resection surface obtained with the ADPJ system than that with soft coagulation (p = 0.02). Furthermore, using the excised specimens of renal cell carcinoma, we measured the breaking strength at each site of the human kidney, suggesting the applicability of this ADPJ to clinical trials. In conclusion, off-clamp LPN with the ADPJ system could be safely performed with attenuated renal damage.

  15. High voltage high brightness electron accelerator with MITL voltage adder coupled to foilless diode

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Poulkey, J.W.; Rovang, D.

    1995-01-01

    The design and analysis of a high brightness electron beam experiment under construction at Sandia National Laboratory is presented. The beam energy is 12 MeV, the current 35-40 kA, the rms radius 0.5 mm, and the pulse duration FWHM 40 ns. The accelerator is SABRE a pulsed inductive voltage adder, and the electron source is a magnetically immersed foilless diode. This experiment has as its goal to stretch the technology to the edge and produce the highest possible electron current in a submillimeter radius beam

  16. Electron bunch structure in energy recovery linac with high-voltage dc photoelectron gun

    Directory of Open Access Journals (Sweden)

    Y. M. Saveliev

    2016-09-01

    Full Text Available The internal structure of electron bunches generated in an injector line with a dc photoelectron gun is investigated. Experiments were conducted on the ALICE (accelerators and lasers in combined experiments energy recovery linac at Daresbury Laboratory. At a relatively low dc gun voltage of 230 kV, the bunch normally consisted of two beamlets with different electron energies, as well as transverse and longitudinal characteristics. The beamlets are formed at the head and the tail of the bunch. At a higher gun voltage of 325 kV, the beam substructure is much less pronounced and could be observed only at nonoptimal injector settings. Experiments and computer simulations demonstrated that the bunch structure develops during the initial beam acceleration in the superconducting rf booster cavity and can be alleviated either by increasing the gun voltage to the highest possible level or by controlling the beam acceleration from the gun voltage in the first accelerating structure.

  17. Reliability of supply of switchgear for auxiliary low voltage in substations extra high voltage to high voltage

    Directory of Open Access Journals (Sweden)

    Perić Dragoslav M.

    2015-01-01

    Full Text Available Switchgear for auxiliary low voltage in substations (SS of extra high voltages (EHV to high voltage (HV - SS EHV/HV kV/kV is of special interest for the functioning of these important SS, as it provides a supply for system of protection and other vital functions of SS. The article addresses several characteristic examples involving MV lines with varying degrees of independence of their supply, and the possible application of direct transformation EHV/LV through special voltage transformers. Auxiliary sources such as inverters and diesel generators, which have limited power and expensive energy, are also used for the supply of switchgear for auxiliary low voltage. Corresponding reliability indices are calculated for all examples including mean expected annual engagement of diesel generators. The applicability of certain solutions of switchgear for auxiliary low voltage SS EHV/HV, taking into account their reliability, feasibility and cost-effectiveness is analyzed too. In particular, the analysis of applications of direct transformation EHV/LV for supply of switchgear for auxiliary low voltage, for both new and existing SS EHV/HV.

  18. 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.

  19. High voltage systems

    International Nuclear Information System (INIS)

    Martin, M.

    1991-01-01

    Industrial processes usually require electrical power. This power is used to drive motors, to heat materials, or in electrochemical processes. Often the power requirements of a plant require the electric power to be delivered at high voltage. In this paper high voltage is considered any voltage over 600 V. This voltage could be as high as 138,000 V for some very large facilities. The characteristics of this voltage and the enormous amounts of power being transmitted necessitate special safety considerations. Safety must be considered during the four activities associated with a high voltage electrical system. These activities are: Design; Installation; Operation; and Maintenance

  20. A new linear induction voltage adder approach to radiography

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Poukey, J.W.; Frost, C.A.; Johnson, D.L.; Shope, S.L.; Halbleib, J.A.; Prestwich, K.R.; Turman, B.N.; Smith, I.

    1992-01-01

    At present, two types of accelerators are being utilized for x-ray radiography: first a linear RF or induction accelerator with multiple accelerating gaps and beam vacuum magnetic transport systems; and second, single gap pulse-power devices with a high voltage Blumlein pulse forming line. The authors present a conceptual design of a new type of linear induction accelerator that can bridge the gap between the two devices. It can produce 30--50-kA electron currents small diameter (∼ 1 mm) and high energy (12--20-MV) beams. There is no beam drifting through the device. The voltage addition of the accelerating gaps occurs at the central self-magnetically insulated cathode electrode. The electron beam is created at the high voltage end in a single gap diode. A magnetically-immersed foilless diode can produce high quality 0.5 mm radius 30--50 kA beams. A short 100--200-kG small bore solenoidal coil is required to maintain the beam radius during transport from the cathode tips to the x-ray converter target, 50--70 cm downstream. The idea of very high impedance MITL voltage adder accelerators was first tested with RADLAC II/SMILE experiments where 12--14-MV, 50-kA 1 cm radius beams were produced with 2--3 mm annulus thickness. A 12.5 m eight-stage voltage adder was utilized, coupled to a 20 kG magnetically immersed foilless diode. In addition the magnetically-immersed foilless diodes with very thin (mm diameter) cathode tips were investigated in experiments with the IBEX accelerator. As an example of this new accelerator technology the authors present the following point design for a 16-MV, 50-kA accelerator producing 1-mm diameter electron beams. The design is based on a cavity fed MITL voltage adder which performs the series addition of the voltage pulses from 16 identical inductively-isolated cavity feed systems. Each cavity is a structure that is driven by one 14 ohm pulse-forming line, providing a 1 MV voltage pulse to the accelerating gap

  1. A Half-Bridge Voltage Balancer with New Controller for Bipolar DC Distribution Systems

    Directory of Open Access Journals (Sweden)

    Byung-Moon Han

    2016-03-01

    Full Text Available This paper proposes a half-bridge voltage balancer with a new controller for bipolar DC distribution systems. The proposed control scheme consists of two cascaded Proportional Integral (PI controls rather than one PI control for balancing the pole voltage. In order to confirm the excellence of voltage balancing performance, a typical bipolar DC distribution system including a half-bridge voltage balancer with proposed controller was analyzed by computer simulations. Experiments with a scaled prototype were also carried out to confirm the simulation results. The half-bridge voltage balancer with proposed controller shows better performance than the half-bridge voltage balancer with one PI control for balancing the pole voltage.

  2. Mathematical modeling of electrical activity of uterine muscle cells.

    Science.gov (United States)

    Rihana, Sandy; Terrien, Jeremy; Germain, Guy; Marque, Catherine

    2009-06-01

    The uterine electrical activity is an efficient parameter to study the uterine contractility. In order to understand the ionic mechanisms responsible for its generation, we aimed at building a mathematical model of the uterine cell electrical activity based upon the physiological mechanisms. First, based on the voltage clamp experiments found in the literature, we focus on the principal ionic channels and their cognate currents involved in the generation of this electrical activity. Second, we provide the methodology of formulations of uterine ionic currents derived from a wide range of electrophysiological data. The model is validated step by step by comparing simulated voltage-clamp results with the experimental ones. The model reproduces successfully the generation of single spikes or trains of action potentials that fit with the experimental data. It allows analyzing ionic channels implications. Likewise, the calcium-dependent conductance influences significantly the cellular oscillatory behavior.

  3. C-terminal modulatory domain controls coupling of voltage-sensing to pore opening in Cav1.3 L-type Ca(2+) channels.

    Science.gov (United States)

    Lieb, Andreas; Ortner, Nadine; Striessnig, Jörg

    2014-04-01

    Activity of voltage-gated Cav1.3 L-type Ca(2+) channels is required for proper hearing as well as sinoatrial node and brain function. This critically depends on their negative activation voltage range, which is further fine-tuned by alternative splicing. Shorter variants miss a C-terminal regulatory domain (CTM), which allows them to activate at even more negative potentials than C-terminally long-splice variants. It is at present unclear whether this is due to an increased voltage sensitivity of the Cav1.3 voltage-sensing domain, or an enhanced coupling of voltage-sensor conformational changes to the subsequent opening of the activation gate. We studied the voltage-dependence of voltage-sensor charge movement (QON-V) and of current activation (ICa-V) of the long (Cav1.3L) and a short Cav1.3 splice variant (Cav1.342A) expressed in tsA-201 cells using whole cell patch-clamp. Charge movement (QON) of Cav1.3L displayed a much steeper voltage-dependence and a more negative half-maximal activation voltage than Cav1.2 and Cav3.1. However, a significantly higher fraction of the total charge had to move for activation of Cav1.3 half-maximal conductance (Cav1.3: 68%; Cav1.2: 52%; Cav3.1: 22%). This indicated a weaker coupling of Cav1.3 voltage-sensor charge movement to pore opening. However, the coupling efficiency was strengthened in the absence of the CTM in Cav1.342A, thereby shifting ICa-V by 7.2 mV to potentials that were more negative without changing QON-V. We independently show that the presence of intracellular organic cations (such as n-methyl-D-glucamine) induces a pronounced negative shift of QON-V and a more negative activation of ICa-V of all three channels. These findings illustrate that the voltage sensors of Cav1.3 channels respond more sensitively to depolarization than those of Cav1.2 or Cav3.1. Weak coupling of voltage sensing to pore opening is enhanced in the absence of the CTM, allowing short Cav1.342A splice variants to activate at lower voltages

  4. del Nido versus St. Thomas Cardioplegia Solutions: A Single-Center Retrospective Analysis of Post Cross-Clamp Defibrillation Rates.

    Science.gov (United States)

    Buel, Shane T; Striker, Carrie Whittaker; O'Brien, James E

    2016-06-01

    There are many cardioplegia solutions currently in use for pediatric cardiopulmonary bypass (CPB). The most common being del Nido solution. Another common cardioplegia solution used for pediatric CPB is St. Thomas. In October 2014, Children's Mercy Kansas City changed from the use of modified St. Thomas to del Nido. This study compared rates of post cross-clamp fibrillation requiring defibrillation between del Nido solution and modified St. Thomas solution stratified by weight at Children's Mercy Kansas City. This retrospective study consisted of 394 patients who underwent cardiac surgery requiring cardioplegia between January 1, 2014 and July 31, 2015. The outcome measured was defibrillation upon cross-clamp removal. Statistical significance was determined using Fishers exact test with a two-sided significance level of .05. Incidence of defibrillation post cross-clamp removal was 4.4% in the del Nido group and 26.8% in the St. Thomas group (p Thomas group (p Thomas group (p Thomas group (p 60-kg category had an incidence of defibrillation of 16.7% in the del Nido group and 63% in the St. Thomas group (p Thomas and del Nido cardioplegia solutions. Analyses of weight stratifications demonstrate a decrease in the rate of defibrillation post cross-clamp removal in all categories within the del Nido group.

  5. Flow characterization and patch clamp dose responses using jet microfluidics in a tubeless microfluidic device.

    Science.gov (United States)

    Resto, Pedro J; Bhat, Abhishek; Stava, Eric; Lor, Chong; Merriam, Elliot; Diaz-Rivera, Ruben E; Pearce, Robert; Blick, Robert; Williams, Justin C

    2017-11-01

    Surface tension passive pumping is a way to actuate flow without the need for pumps, tubing or valves by using the pressure inside small drop to move liquid via a microfluidic channel. These types of tubeless devices have typically been used in cell biology. Herein we present the use of tubeless devices as a fluid exchange platform for patch clamp electrophysiology. Inertia from high-speed droplets and jets is used to create flow and perform on-the-fly mixing of solutions. These are then flowed over GABA transfected HEK cells under patch in order to perform a dose response analysis. TIRF imaging and electrical recordings are used to study the fluid exchange properties of the microfluidic device, resulting in 0-90% fluid exchange times of hundreds of milliseconds. COMSOL is used to model flow and fluid exchange within the device. Patch-clamping experiments show the ability to use high-speed passive pumping and its derivatives for studying peak dose responses, but not for studying ion channel kinetics. Our system results in fluid exchange times slower than when using a standard 12-barrel application system and is not as stable as traditional methods, but it offers a new platform with added functionality. Surface tension passive pumping and tubeless devices can be used in a limited fashion for electrophysiology. Users may obtain peak dose responses but the system, in its current form, is not capable of fluid exchange fast enough to study the kinetics of most ion channels. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Low-Energy Real-Time OS Using Voltage Scheduling Algorithm for Variable Voltage Processors

    OpenAIRE

    Okuma, Takanori; Yasuura, Hiroto

    2001-01-01

    This paper presents a real-time OS based on $ mu $ITRON using proposed voltage scheduling algorithm for variable voltage processors which can vary supply voltage dynamically. The proposed voltage scheduling algorithms assign voltage level for each task dynamically in order to minimize energy consumption under timing constraints. Using the presented real-time OS, running tasks with low supply voltage leads to drastic energy reduction. In addition, the presented voltage scheduling algorithm is ...

  7. Acute phase response in lactating dairy cows during hyperinsulinemic hypoglycaemic and hyperinsulinemic euglycaemic clamps and after intramammary LPS challenge.

    Science.gov (United States)

    De Matteis, L; Bertoni, G; Lombardelli, R; Wellnitz, O; Van Dorland, H A; Vernay, M C M B; Bruckmaier, R M; Trevisi, E

    2017-06-01

    The link between energy availability, turnover of energy substrates and the onset of inflammation in dairy cows is complex and poorly investigated. To clarify this, plasma inflammatory variables were measured in mid-lactating dairy cows allocated to three groups: hyperinsulinemic hypoglycaemic clamp, induced by insulin infusion (HypoG, n = 5); hyperinsulinemic euglycaemic clamp, induced by insulin and glucose infusion (EuG; n = 6); control, receiving a saline solution infusion (NaCl; n = 6). At 48 h after the start of i.v. infusions, two udder quarters per cow were challenged with 200 μg of E. coli lipopolysaccharide (LPS). Individual blood samples were taken before clamps, before LPS challenge (i.e. 48 h after clamps) and 6.5 h after. At 48 h, positive acute phase proteins (posAPP) did not differ among groups, whereas albumin and cholesterol (index of lipoproteins), negative APP (negAPP), were lower (p insulin at the tissue-level makes dairy cows more susceptible to inflammatory events. In contrast, HypoG seems to attenuate the inflammatory response. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.

  8. Impact of delayed umbilical cord clamping on public cord blood donations: can we help future patients and benefit infant donors?

    Science.gov (United States)

    Ciubotariu, Rodica; Scaradavou, Andromachi; Ciubotariu, Ilinca; Tarnawski, Michal; Lloyd, Sara; Albano, Maria; Dobrila, Ludy; Rubinstein, Pablo; Grunebaum, Amos

    2018-03-25

    Cord blood (CB) is a widely accepted stem cell source and its clinical utilization depends, to a great extent, on its cell content. Birth-to-clamping (BTC) time of umbilical cord determines placental transfusion to the newborn, and the remaining blood that can be collected and banked. The 2017 Committee Opinion of the American College of Obstetrics and Gynecologists (ACOG) recommends a delay of "at least 30-60 seconds" before clamping the cord for all newborns to ensure adequate iron stores. The impact of delayed cord clamping (DCC) on public CB banking can be substantial. Cord blood units (CBUs) collected from 1210 mothers at one hospital were evaluated for total nucleated cells (TNCs) and weight/volume based on time to clamping. Bank staff recorded BTC time in seconds as reported by obstetricians; collections were performed ex utero. Immediate clamping was defined as BTC of less than 30 seconds, whereas DCC was defined as BTC of 30 seconds or more. Cord clamping was immediate in 903 (75%) and delayed in 307 (25%) deliveries. Successful recovery (% clinical CBUs) decreased 10-fold with DCC of more than 60 seconds (22% vs. 2.4%, p < 0.001). CBUs collected after DCC of more than 60 seconds had significantly lower TNC counts than those after DCC of less than 60 seconds (p < 0.0001). Furthermore, 38% to 46% of CBUs after DCC of more than 60 seconds had volume of less than 40 mL. Our study indicates that DCC of 30 to 60 seconds has a small negative impact on collection of high-TNC-count CBUs. However, increasing BTC to more than 60 seconds decreases significantly both TNC content and volume, reducing drastically the chances of obtaining clinically useful CBUs. © 2018 AABB.

  9. Consciousness can reduce the voltage of the output signal of solar cell

    Science.gov (United States)

    Cao, Dayong

    2011-03-01

    When the sun's light radiate on the solar cell, it can produce the output signal as the pho- tocurrent. We use the Data Acquisition Modules to record the voltage of the output signals. The v1 is voltage of the photocurrent of solar cell1; The v2 is the one of solar cell2. And these two solar cells stay side by side. When we record the voltages from the morning to the noon, the voltages will go up, and the v1 is bigger than the v2 during this time. But in other experi- menter, not only sun's light ratiade on two solar cells, but also consciousness act on two solar cells. Not only I can use consciousness to reduce the growth voltage of the output signals, but also can change the v1 to be littler than the v2. The experiment was conducted on Sep. 2010. When light of lamp radiate on two solar cells, I can reduce v1, at the same time, can augment v2. These experiments had been finished in Los Angeles, Oct. 26th. And the experiment show that the consciousness active function differ from the passive function of conditioned reflex (of Pavlov). There is the physical system of the mass, energy, space and time-MEST; There is the spirited system of the mind, consciousness, emotion and desire-MECD; the information system is the code system. We can use the consciousness change the electron-structure of solar cell by the interaction of the information.

  10. Spectrum analysis of a voltage source converter due to semiconductor voltage drops

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg; Eltouki, Mustafa

    2017-01-01

    It is known that power electronic voltage source converters are non-ideal. This paper presents a state-of-the-art review on the effect of semiconductor voltage drop on the output voltage spectrum, using single-phase H-bridge two-level converter topology with natural sampled pulse width modulation....... The paper describes the analysis of output voltage spectrum, when the semiconductor voltage drop is added. The results of the analysis of the spectral contribution including and excluding semiconductor voltage drop reveal a good agreement between the theoretical results, simulations and laboratory...

  11. Activation of CRH receptor type 1 expressed on glutamatergic neurons increases excitability of CA1 pyramidal neurons by the modulation of voltage-gated ion channels

    Directory of Open Access Journals (Sweden)

    Stephan eKratzer

    2013-07-01

    Full Text Available Corticotropin-releasing hormone (CRH plays an important role in a substantial number of patients with stress-related mental disorders, such as anxiety disorders and depression. CRH has been shown to increase neuronal excitability in the hippocampus, but the underlying mechanisms are poorly understood. The effects of CRH on neuronal excitability were investigated in acute hippocampal brain slices. Population spikes (PS and field excitatory postsynaptic potentials (fEPSP were evoked by stimulating Schaffer-collaterals and recorded simultaneously from the somatic and dendritic region of CA1 pyramidal neurons. CRH was found to increase PS amplitudes (mean  Standard error of the mean; 231.8  31.2% of control; n=10 while neither affecting fEPSPs (104.3 ± 4.2%; n=10 nor long-term potentiation (LTP. However, when Schaffer-collaterals were excited via action potentials (APs generated by stimulation of CA3 pyramidal neurons, CRH increased fEPSP amplitudes (119.8 ± 3.6%; n=8 and the magnitude of LTP in the CA1 region. Experiments in slices from transgenic mice revealed that the effect on PS amplitude is mediated exclusively by CRH receptor 1 (CRHR1 expressed on glutamatergic neurons. The effects of CRH on PS were dependent on phosphatase-2B, L- and T-type calcium channels and voltage-gated potassium channels but independent on intracellular Ca2+-elevation. In patch-clamp experiments, CRH increased the frequency and decay times of APs and decreased currents through A-type and delayed-rectifier potassium channels. These results suggest that CRH does not affect synaptic transmission per se, but modulates voltage-gated ion currents important for the generation of APs and hence elevates by this route overall neuronal activity.

  12. Active signal conduction through the sensory dendrite of a spider mechanoreceptor neuron.

    Science.gov (United States)

    Gingl, Ewald; French, Andrew S

    2003-07-09

    Rapid responses to sensory stimulation are crucial for survival. This must be especially true for mechanical stimuli containing temporal information, such as vibration. Sensory transduction occurs at the tips of relatively long sensory dendrites in many mechanoreceptors of both vertebrates and invertebrates, but little is known about the electrical properties of these crucial links between transduction and action potential generation. The VS-3 slit-sense organ of the spider Cupiennius salei contains bipolar mechanosensory neurons that allow voltage-clamp recording from the somata, whereas mechanotransduction occurs at the tips of 100- to 200-microm-long sensory dendrites. We studied the properties of VS-3 sensory dendrites using three approaches. Voltage-jump experiments measured the spread of voltage outward from the soma by observing total mechanically transduced charge recovered at the soma as a function of time after a voltage jump. Frequency-response measurements between pseudorandom mechanical stimulation and somatic membrane potential estimated the passive cable properties of the dendrite for voltage spread in the opposite direction. Both of these sets of data indicated that the dendritic cable would significantly attenuate and retard a passively propagated receptor potential. Finally, current-clamp observations of receptor potentials and action potentials indicated that action potentials normally start at the distal dendrites and propagate regeneratively to the soma, reducing the temporal delay of passive conduction.

  13. Design, experiments and simulation of voltage transformers on the basis of a differential input D-dot sensor.

    Science.gov (United States)

    Wang, Jingang; Gao, Can; Yang, Jie

    2014-07-17

    Currently available traditional electromagnetic voltage sensors fail to meet the measurement requirements of the smart grid, because of low accuracy in the static and dynamic ranges and the occurrence of ferromagnetic resonance attributed to overvoltage and output short circuit. This work develops a new non-contact high-bandwidth voltage measurement system for power equipment. This system aims at the miniaturization and non-contact measurement of the smart grid. After traditional D-dot voltage probe analysis, an improved method is proposed. For the sensor to work in a self-integrating pattern, the differential input pattern is adopted for circuit design, and grounding is removed. To prove the structure design, circuit component parameters, and insulation characteristics, Ansoft Maxwell software is used for the simulation. Moreover, the new probe was tested on a 10 kV high-voltage test platform for steady-state error and transient behavior. Experimental results ascertain that the root mean square values of measured voltage are precise and that the phase error is small. The D-dot voltage sensor not only meets the requirement of high accuracy but also exhibits satisfactory transient response. This sensor can meet the intelligence, miniaturization, and convenience requirements of the smart grid.

  14. J-integral analysis of heterogeneous mismatched girth welds in clamped single-edge notched tension specimens

    International Nuclear Information System (INIS)

    Hertelé, Stijn; De Waele, Wim; Verstraete, Matthias; Denys, Rudi; O'Dowd, Noel

    2014-01-01

    Flaw assessment procedures require a quantification of crack driving force, and such procedures are generally based on the assumption of weld homogeneity. However, welds generally have a heterogeneous microstructure, which will influence the crack driving force. This paper describes a stress-based methodology to assess complex heterogeneous welds using a J-based approach. Clamped single-edge notched tension specimens, representative of girth weld flaws, are analyzed and the influence of weld heterogeneity on crack driving force has been determined. The use of a modified limit load for heterogeneous welds is proposed, suitable for implementation in a ‘homogenized’ J-integral estimation scheme. It follows from an explicit modification of an existing solution for centre cracked tension specimens. The proposed solution provides a good estimate of crack driving force and any errors in the approximation may be accounted for by means of a small safety factor on load bearing capacity. - Highlights: • We present a crack driving force estimation procedure for heterogeneous welds. • The procedure is based on a ‘homogenized’ version of the EPRI equation. • Complex welds are translated into equivalent idealized mismatched welds. • The procedure is validated for clamped SE(T) specimens. • A mismatch limit load for clamped SE(T) specimens is developed

  15. Five-Level Z-Source Neutral Point-Clamped Inverter

    DEFF Research Database (Denmark)

    Gao, F.; Loh, P.C.; Blaabjerg, Frede

    2007-01-01

    This paper proposes a five-level Z-source neutralpoint- clamped (NPC) inverter with two Z-source networks functioning as intermediate energy storages coupled between dc sources and NPC inverter circuitry. Analyzing the operational principles of Z-source network with partial dclink shoot......-through scheme reveals the hidden theories in the five-level Z-source NPC inverter unlike the operational principle appeared in the general two-level Z-source inverter, so that the five-level Z-source NPC inverter can be designed with the modulation of carrier-based phase disposition (PD) or alternative phase...

  16. Experimental validation of prototype high voltage bushing

    Science.gov (United States)

    Shah, Sejal; Tyagi, H.; Sharma, D.; Parmar, D.; M. N., Vishnudev; Joshi, K.; Patel, K.; Yadav, A.; Patel, R.; Bandyopadhyay, M.; Rotti, C.; Chakraborty, A.

    2017-08-01

    Prototype High voltage bushing (PHVB) is a scaled down configuration of DNB High Voltage Bushing (HVB) of ITER. It is designed for operation at 50 kV DC to ensure operational performance and thereby confirming the design configuration of DNB HVB. Two concentric insulators viz. Ceramic and Fiber reinforced polymer (FRP) rings are used as double layered vacuum boundary for 50 kV isolation between grounded and high voltage flanges. Stress shields are designed for smooth electric field distribution. During ceramic to Kovar brazing, spilling cannot be controlled which may lead to high localized electrostatic stress. To understand spilling phenomenon and precise stress calculation, quantitative analysis was performed using Scanning Electron Microscopy (SEM) of brazed sample and similar configuration modeled while performing the Finite Element (FE) analysis. FE analysis of PHVB is performed to find out electrical stresses on different areas of PHVB and are maintained similar to DNB HV Bushing. With this configuration, the experiment is performed considering ITER like vacuum and electrical parameters. Initial HV test is performed by temporary vacuum sealing arrangements using gaskets/O-rings at both ends in order to achieve desired vacuum and keep the system maintainable. During validation test, 50 kV voltage withstand is performed for one hour. Voltage withstand test for 60 kV DC (20% higher rated voltage) have also been performed without any breakdown. Successful operation of PHVB confirms the design of DNB HV Bushing. In this paper, configuration of PHVB with experimental validation data is presented.

  17. High voltage high brightness electron accelerators with MITL voltage adder coupled to foilless diodes

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Poukey, J.W.; Frost, C.A.; Shope, S.L.; Halbleib, J.A.; Turman, B.N.

    1993-01-01

    During the last ten years the authors have extensively studied the physics and operation of magnetically-immersed electron foilless diodes. Most of these sources were utilized as injectors to high current, high energy linear induction accelerators such as those of the RADLAC family. Recently they have experimentally and theoretically demonstrated that foilless diodes can be successfully coupled to self-magnetically insulated transmission line voltage adders to produce very small high brightness, high definition (no halo) electron beams. The RADLAC/SMILE experience opened the path to a new approach in high brightness, high energy induction accelerators. There is no beam drifting through the device. The voltage addition occurs in a center conductor, and the beam is created at the high voltage end in an applied magnetic field diode. This work was motivated by the remarkable success of the HERMES-III accelerator and the need to produce small radius, high energy, high current electron beams for air propagation studies and flash x-ray radiography. In this paper they present experimental results compared with analytical and numerical simulations in addition to design examples of devices that can produce multikiloamp electron beams of as high as 100 MV energies and radii as small as 1 mm

  18. Multifunction Voltage-Mode Filter Using Single Voltage Differencing Differential Difference Amplifier

    Directory of Open Access Journals (Sweden)

    Chaichana Amornchai

    2017-01-01

    Full Text Available In this paper, a voltage mode multifunction filter based on single voltage differencing differential difference amplifier (VDDDA is presented. The proposed filter with three input voltages and single output voltage is constructed with single VDDDA, two capacitors and two resistors. Its quality factor can be adjusted without affecting natural frequency. Also, the natural frequency can be electronically tuned via adjusting of bias current. The filter can offer five output responses, high-pas (HP, band-pass (BP, band-reject (BR, low-pass (LP and all-ass (AP functions in the same circuit topology. The output response can be selected by choosing the suitable input voltage without the component matching condition and the requirement of additional double gain voltage amplifier. PSpice simulation results to confirm an operation of the proposed filter correspond to the theory.

  19. Treatment of emulsified oils by electrocoagulation: pulsed voltage applications.

    Science.gov (United States)

    Genc, Ayten; Bakirci, Busra

    2015-01-01

    The effect of pulsed voltage application on energy consumption during electrocoagulation was investigated. Three voltage profiles having the same arithmetic average with respect to time were applied to the electrodes. The specific energy consumption for these profiles were evaluated and analyzed together with oil removal efficiencies. The effects of applied voltages, electrode materials, electrode configurations, and pH on oil removal efficiency were determined. Electrocoagulation experiments were performed by using synthetic and real wastewater samples. The pulsed voltages saved energy during the electrocoagulation process. In continuous operation, energy saving was as high as 48%. Aluminum electrodes used for the treatment of emulsified oils resulted in higher oil removal efficiencies in comparison with stainless steel and iron electrodes. When the electrodes gap was less than 1 cm, higher oil removal efficiencies were obtained. The highest oil removal efficiencies were 95% and 35% for the batch and continuous operating modes, respectively.

  20. A novel ZVS high voltage power supply for micro-channel plate photomultiplier tubes

    International Nuclear Information System (INIS)

    Pei, Chengquan; Tian, Jinshou; Liu, Zhen; Qin, Hong; Wu, Shengli

    2017-01-01

    A novel resonant high voltage power supply (HVPS) with zero voltage switching (ZVS), to reduce the voltage stress on switching devices and improve conversion efficiency, is proposed. The proposed HVPS includes a drive circuit, a transformer, several voltage multiplying circuits, and a regulator circuit. The HVPS contains several secondary windings that can be precisely regulated. The proposed HVPS performed better than the traditional resistor voltage divider, which requires replacing matching resistors resulting in resistor dispersibility in the Micro-Channel Plate (MCP). The equivalent circuit of the proposed HVPS was established and the operational principle analyzed. The entire switching element can achieve ZVS, which was validated by a simulation and experiments. The properties of this HVPS were tested including minimum power loss (240 mW), maximum power loss (1 W) and conversion efficiency (85%). The results of this research are that the proposed HVPS was suitable for driving the micro-channel plate photomultiplier tube (MCP-PMT). It was therefore adopted to test the MCP-PMT, which will be used in Daya Bay reactor neutrino experiment II in China.