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Sample records for voltage clamp studies

  1. 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

  2. How the early voltage clamp studies of José del Castillo inform "modern" neuroscience.

    Science.gov (United States)

    Zottoli, Steven J

    2012-10-01

    The description of ionic currents that flow across the membrane of the squid giant axon during an action potential sparked an interest in determining whether there were similar currents in vertebrates. The preparation of choice was the node of Ranvier in single myelinated fibers in frog. José del Castillo spent 3 years on the United States mainland from 1956 to 1959. During that time, he collaborated with Jerome Y. Lettvin and John W. Moore. I discuss how these individuals met one another and some of their scientific discoveries using the voltage clamp to study squid giant axons and frog nodes. Much of this work was conducted at the Marine Biological Laboratory in Woods Hole, MA, and I attempt to convey a sense of the unique scientific "melting pot" that existed at the Marine Biological Laboratory and the broader effect that del Castillo had on "modern" neuroscience.

  3. Voltage-clamp studies of transient inward current and mechanical oscillations induced by ouabain in ferret papillary muscle.

    Science.gov (United States)

    Karagueuzian, H S; Katzung, B G

    1982-06-01

    1. We studied the effects of a toxic concentration of ouabain on transmembrane electrical activity and on mechanical behaviour of right ventricular papillary muscles from ferrets in a single sucrose-gap using current clamp and voltage clamp.2. Ouabain (1.4-1.8 muM) induced oscillatory after-potentials and after-concentrations in current-clamp experiments. Voltage clamp showed that the oscillatory after-potential was caused by a transient inward current, similar to that in Purkinje fibres.3. The transient current had a sigmoidal dependence on the preceding (activating) voltage step V1, with a treshold around -13 mV and a plateau between +10 and 20 mV. There was a decline in current amplitude for more positive clamps. When activated by a fixed V1 voltage step, and measured at different repolarization levels V2, the transient current manifested an inverse dependence on V2 between -50 and -10 mV. No outward transient current could be detected. Total replacement of Na in the bathing medium by Tris or by sucrose abolished the transient current.4. Ouabain caused an increase of phasic (twitch) tension responses to voltage steps at all potentials without shifting the curve relating these variables on the voltage axis. The drug evoked an even greater increase in the tonic tension responses.5. After prolonged exposure, oscillatory mechanical responses were frequently recorded during positive voltage steps. Unlike the after-contraction, these mechanical fluctuations were not consistently damped and were not accompanied by detectable synchronous current fluctuations. Catecholamines and dibutyryl cyclic AMP markedly reduced the amplitude of the tonic contraction and the mechanical oscillations but increased their frequency. Caffeine had no effect on the tonic contraction amplitude but abolished the fluctuations.6. These results support the proposal that Ca is transiently released from the overloaded sarcoplasmic reticulum in ouabain-intoxicated muscle and may evoke oscillatory

  4. How cesium dialysis affects the passive properties of pyramidal neurons: implications for voltage clamp studies of persistent sodium current

    Energy Technology Data Exchange (ETDEWEB)

    Fleidervish, Ilya A; Libman, Lior [Koret School of Veterinary Medicine, Hebrew University of Jerusalem, PO Box 12, Rehovot 76100 (Israel)], E-mail: fleider@agri.huji.ac.il

    2008-03-15

    In order to accurately understand and model neuronal integration in the brain, we must know the biophysical properties of channels that are located far from the soma, in the axonal and dendritic membranes of central nerve cells. Reliable electrophysiological measurements in these regions are difficult to obtain, because the processes are too tiny to directly study with an electrode. One common strategy is to record with a somatic electrode that contains Cs{sup +}, to dialyze the intracellular space with this K{sup +} channel blocker, and thereby to render the neuron electrotonically compact. Does this work? Here, we combine the experimental and modeling techniques to determine the extent to which a whole-cell voltage clamp, established with a Cs{sup +}-containing pipette in the soma of a cortical pyramidal cell, attains adequate voltage control of distal neuronal processes. We focus on the low-voltage-activated, slowly inactivating 'persistent' Na{sup +} current (I{sub NaP}), that plays a crucial role in determining neuronal excitability and synaptic integration.

  5. How cesium dialysis affects the passive properties of pyramidal neurons: implications for voltage clamp studies of persistent sodium current

    Science.gov (United States)

    Fleidervish, Ilya A.; Libman, Lior

    2008-03-01

    In order to accurately understand and model neuronal integration in the brain, we must know the biophysical properties of channels that are located far from the soma, in the axonal and dendritic membranes of central nerve cells. Reliable electrophysiological measurements in these regions are difficult to obtain, because the processes are too tiny to directly study with an electrode. One common strategy is to record with a somatic electrode that contains Cs+, to dialyze the intracellular space with this K+ channel blocker, and thereby to render the neuron electrotonically compact. Does this work? Here, we combine the experimental and modeling techniques to determine the extent to which a whole-cell voltage clamp, established with a Cs+-containing pipette in the soma of a cortical pyramidal cell, attains adequate voltage control of distal neuronal processes. We focus on the low-voltage-activated, slowly inactivating 'persistent' Na+ current (INaP), that plays a crucial role in determining neuronal excitability and synaptic integration.

  6. Imperfect space clamp permits electrotonic interactions between inhibitory and excitatory synaptic conductances, distorting voltage clamp recordings.

    Directory of Open Access Journals (Sweden)

    Alon Poleg-Polsky

    Full Text Available The voltage clamp technique is frequently used to examine the strength and composition of synaptic input to neurons. Even accounting for imperfect voltage control of the entire cell membrane ("space clamp", it is often assumed that currents measured at the soma are a proportional indicator of the postsynaptic conductance. Here, using NEURON simulation software to model somatic recordings from morphologically realistic neurons, we show that excitatory conductances recorded in voltage clamp mode are distorted significantly by neighboring inhibitory conductances, even when the postsynaptic membrane potential starts at the reversal potential of the inhibitory conductance. Analogous effects are observed when inhibitory postsynaptic currents are recorded at the reversal potential of the excitatory conductance. Escape potentials in poorly clamped dendrites reduce the amplitude of excitatory or inhibitory postsynaptic currents recorded at the reversal potential of the other conductance. In addition, unclamped postsynaptic inhibitory conductances linearize the recorded current-voltage relationship of excitatory inputs comprising AMPAR and NMDAR-mediated components, leading to significant underestimation of the relative contribution by NMDARs, which are particularly sensitive to small perturbations in membrane potential. Voltage clamp accuracy varies substantially between neurons and dendritic arbors of different morphology; as expected, more reliable recordings are obtained from dendrites near the soma, but up to 80% of the synaptic signal on thin, distant dendrites may be lost when postsynaptic interactions are present. These limitations of the voltage clamp technique may explain how postsynaptic effects on synaptic transmission could, in some cases, be attributed incorrectly to presynaptic mechanisms.

  7. An ANN Based Capicitor Voltage Balancing Method For Neutral Point Clamped Multi-Level Inverter

    Directory of Open Access Journals (Sweden)

    P.J.S. Praveen,

    2015-11-01

    Full Text Available Multi-level inverters are became popular for usage in medium voltage, low voltage power applications due to flexibility in control and better performance characteristics in terms of harmonic regulation. Neutral point clamped are popular as they require less number of sources as their input when compared with their counter parts i.e. cascaded multi-level inverters and found to be reliable when compared with flying capacitor based multi-level inverters. But when neutral clamped technologies are used for generation of three-phase voltages, the capacitors that are connected at input side experiences imbalance in their voltages, this makes neutral point clamped multi-level inverters less reliable. In the proposed work an attempt is made to study circuits that balances the capacitor voltages and a scheme is investigated for balancing the capacitor voltages. Method proposed in [1] uses PID controller for balancing the capacitor voltages. In this project PI based control scheme and artificial neural network (ANN based control scheme for the front end circuit shown in [1] are designed for achieving balance among the capacitor voltages. The proposed control scheme is simulated with the help of Simpowersystems block set and neural network toolbox of MATLAB software for different load conditions. Results obtained from ANN based controller and PI controller are presented.

  8. 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.

  9. FPGA in-the-loop simulations of cardiac excitation model under voltage clamp conditions

    Science.gov (United States)

    Othman, Norliza; Adon, Nur Atiqah; Mahmud, Farhanahani

    2017-01-01

    Voltage clamp technique allows the detection of single channel currents in biological membranes in identifying variety of electrophysiological problems in the cellular level. In this paper, a simulation study of the voltage clamp technique has been presented to analyse current-voltage (I-V) characteristics of ion currents based on Luo-Rudy Phase-I (LR-I) cardiac model by using a Field Programmable Gate Array (FPGA). Nowadays, cardiac models are becoming increasingly complex which can cause a vast amount of time to run the simulation. Thus, a real-time hardware implementation using FPGA could be one of the best solutions for high-performance real-time systems as it provides high configurability and performance, and able to executes in parallel mode operation. For shorter time development while retaining high confidence results, FPGA-based rapid prototyping through HDL Coder from MATLAB software has been used to construct the algorithm for the simulation system. Basically, the HDL Coder is capable to convert the designed MATLAB Simulink blocks into hardware description language (HDL) for the FPGA implementation. As a result, the voltage-clamp fixed-point design of LR-I model has been successfully conducted in MATLAB Simulink and the simulation of the I-V characteristics of the ionic currents has been verified on Xilinx FPGA Virtex-6 XC6VLX240T development board through an FPGA-in-the-loop (FIL) simulation.

  10. Novel Low Loss Active Voltage Clamp Circuit for Series Connection of RCGCT thyristors

    Science.gov (United States)

    Ito, Hiroshi; Suzuki, Akihiro; Iwata, Akihiko

    This paper describes novel low loss active voltage clamp circuits for the series connection of RCGCT thyristors. For high voltage converters the series connection of power semiconductor devices is an essential technique for direct switching of high voltages. Several protection circuits have been applied to the series connection of RCGCT thyristors such as CRD snubber circuits which suppress over-voltages across RCGCT thyristors, and voltage balancing resistors to equalize voltage sharing in steady states. However, significant losses in these protection circuits lower the converter’s efficiency. We propose novel low-loss protection circuits, which have active voltage clamp snubber circuits and static voltage balancing circuits. The clamp capacitor voltage of the active voltage clamp snubber circuits are designed to be higher than the equally divided DC-Link voltage. This method can reduce the loss of the clamp circuit to no more than 1/10 of that of the conventional CRD snubber. Also the static voltage balancing circuits compensate for the voltage imbalance generated by the difference in the leakage current between the series connection RCGCT thyristors.

  11. 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...

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

    Institute of Scientific and Technical Information of China (English)

    YU Lian-Chun; MA Jun; ZHANG Guo-Yong; CHEN Yong

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-07-01

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

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

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

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

  15. 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

    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......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...... are conducted, and the results have verified the proposed converter and control strategies....

  16. High Efficiency Interleaved Active Clamped Dc-Dc Converter with Fuel Cell for High Voltage Applications

    Directory of Open Access Journals (Sweden)

    Sona P

    2014-02-01

    Full Text Available A high efficiency interleaved ZVS active clamped current fed dc-dc converter is proposed in this paper specially used for fuel cell applications. As the fuel cell output is very low we are in need of a step up dc-dc converter. Here a current fed dc-dc converter is used. Two current fed dc-dc converters are interleaved by connecting their inputs in parallel and outputs in series. With this proposed methodology input current ripples in the fuel cell stacks can be reduced and a regulated output voltage ripples can be obtained. The active clamping circuit used in this model absorbs the turn off voltage spikes hence low voltage devices with low on state resistance can be used.Voltage doubler circuits will give double the output voltage than normal with smaller transformer turns ratio and flexibility. The proposed method is simulated in MATLAB for verifying the accuracy of the proposed design.

  17. Calcium Release in Frog Cut Twitch Fibers Exposed to Different Ionic Environments under Voltage Clamp

    National Research Council Canada - National Science Library

    Hui, Chiu Shuen

    1999-01-01

    Calcium release was measured in highly stretched frog cut twitch fibers mounted in a double Vaseline-gap voltage clamp chamber, with the internal solution containing 20 mM EGTA plus 0.4 or 1.8 mM added calcium...

  18. 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.

  19. Voltage- and space-clamp errors associated with the measurement of electrotonically remote synaptic events.

    Science.gov (United States)

    Spruston, N; Jaffe, D B; Williams, S H; Johnston, D

    1993-08-01

    1. The voltage- and space-clamp errors associated with the use of a somatic electrode to measure current from dendritic synapses are evaluated using both equivalent-cylinder and morphologically realistic models of neuronal dendritic trees. 2. As a first step toward understanding the properties of synaptic current distortion under voltage-clamp conditions, the attenuation of step and sinusoidal voltage changes are evaluated in equivalent cylinder models. Demonstration of the frequency-dependent attenuation of voltage in the cable is then used as a framework for understanding the distortion of synaptic currents generated at sites remote from the somatic recording electrode and measured in the voltage-clamp recording configuration. 3. Increases in specific membrane resistivity (Rm) are shown to reduce steady-state voltage attenuation, while producing only minimal reduction in attenuation of transient voltage changes. Experimental manipulations that increase Rm therefore improve the accuracy of estimates of reversal potential for electrotonically remote synapses, but do not significantly reduce the attenuation of peak current. In addition, increases in Rm have the effect of slowing the kinetics of poorly clamped synaptic currents. 4. The effects of the magnitude of the synaptic conductance and its kinetics on the measured synaptic currents are also examined and discussed. The error in estimating parameters from measured synaptic currents is greatest for synapses with fast kinetics and large conductances. 5. A morphologically realistic model of a CA3 pyramidal neuron is used to demonstrate the generality of the conclusions derived from equivalent cylinder models. The realistic model is also used to fit synaptic currents generated by stimulation of mossy fiber (MF) and commissural/associational (C/A) inputs to CA3 neurons and to estimate the amount of distortion of these measured currents. 6. Anatomic data from the CA3 pyramidal neuron model are used to construct a

  20. 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....

  1. Dynamic Study of a Capacitive MEMS Switch with Double Clamped-Clamped Microbeams

    Directory of Open Access Journals (Sweden)

    Hatem Samaali

    2014-01-01

    Full Text Available We study a capacitive MEMS switch composed of two clamped-clamped exible microbeams. We first develop a mathematical model for the MEMS switch where the upper microbeam represents the ground transmission line and the lower one represents the central transmission line. An electrostatic force is applied between the two microbeams to yield the switch to its ON and OFF states. We derive the equations of motion of the system and associated boundary conditions and solve the static and dynamic problems using the differential quadratic method. We show that using only nine grid points gives relatively accurate results when compared to those obtained using FEM. We also examine the transient behavior of the microswitch and obtain results indicating that subsequent reduction in actuation voltage, switching time, and power consumption are expected along with relatively good RF performances. ANSYS HFSS simulator is used in this paper to extract the RF characteristics of the microswitch. HFSS simulation results show that the insertion loss is as low as −0.31 dB and that the return loss is better than −12.41 dB at 10 GHz in the ON state. At the OFF state, the isolation is lower than −23 dB in the range of 10 to 50 GHz.

  2. 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

    In traditional neutral-point-clamped (NPC) inverters, two major operating issues encountered are their relatively limited voltage-buck variation range and capacitive-voltage imbalance, which can cause low-order harmonics to appear at the inverter output. Various methodologies have so far been...... been investigated in the context of buck–boost energy conversion, even though relevant techniques for traditional NPC inverters do exist but are generally overburdened by the accompanied switching loss increase and more complex control and hardware circuitries. To address these two topological concerns...... 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...

  3. 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).

  4. 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)

  5. Single molecule study of a processivity clamp sliding on DNA

    Energy Technology Data Exchange (ETDEWEB)

    Laurence, T A; Kwon, Y; Johnson, A; Hollars, C; O?Donnell, M; Camarero, J A; Barsky, D

    2007-07-05

    Using solution based single molecule spectroscopy, we study the motion of the polIII {beta}-subunit DNA sliding clamp ('{beta}-clamp') on DNA. Present in all cellular (and some viral) forms of life, DNA sliding clamps attach to polymerases and allow rapid, processive replication of DNA. In the absence of other proteins, the DNA sliding clamps are thought to 'freely slide' along the DNA; however, the abundance of positively charged residues along the inner surface may create favorable electrostatic contact with the highly negatively charged DNA. We have performed single-molecule measurements on a fluorescently labeled {beta}-clamp loaded onto freely diffusing plasmids annealed with fluorescently labeled primers of up to 90 bases. We find that the diffusion constant for 1D diffusion of the {beta}-clamp on DNA satisfies D {le} 10{sup -14} cm{sup 2}/s, much slower than the frictionless limit of D = 10{sup -10} cm{sup 2}/s. We find that the {beta} clamp remains at the 3-foot end in the presence of E. coli single-stranded binding protein (SSB), which would allow for a sliding clamp to wait for binding of the DNA polymerase. Replacement of SSB with Human RP-A eliminates this interaction; free movement of sliding clamp and poor binding of clamp loader to the junction allows sliding clamp to accumulate on DNA. This result implies that the clamp not only acts as a tether, but also a placeholder.

  6. Substance P-mediated membrane currents in voltage-clamped guinea pig inferior mesenteric ganglion cells.

    Science.gov (United States)

    Griffith, W H; Hills, J M; Brown, D A

    1988-01-01

    Responses to substance P (SP) and to hypogastric nerve stimulation were recorded from voltage-clamped guinea pig inferior mesenteric ganglion (IMG) neurons, and compared with those to muscarine. Muscarine produced a voltage-dependent inward current accompanied by a reduced input conductance and inhibition of IM a time- and voltage-dependent K+-current (Brown and Adams: Nature 283:673-676, 1980). SP also produced an inward current, accompanied by a fall in input conductance (20 out of 31 cells) or a rise in input conductance (7 out of 31 cells). The fall in input conductance was not accompanied by an inhibition of M-current (unlike frog ganglia: Adams et al.: British Journal of Pharmacology 79:330-333, 1983) or an inhibition of the inward rectifier current (unlike globus pallidus neurons: Stanfield et al.: Nature 315:498-501, 1985). Repetitive hypogastric nerve stimulation (10-20 Hz, 2-10 s) produced a slow inward postsynaptic current lasting 1-3 min, with decreases or increases of input conductance matching those produced by SP. The postsynaptic current did not show a consistent or reproducible change in amplitude on varying the holding potential between -90 and -25 mV. It is concluded that SP and hypogastric stimulation produce complex and variable changes in ionic conductance in IMG neurons.

  7. Three Phase Two Leg Neutral Point Clamped Converter with output DC Voltage Regulation and Input Power Factor Correction

    Directory of Open Access Journals (Sweden)

    Bogimi Sirisha

    2012-03-01

    Full Text Available In this paper, a three-phase two leg neutral point clamped (NPC converter is presented for power factor correction and dc-link voltage regulation. The adopted converter has simpler circuit configuration and less number of power switches compared to three-level PWM converter. In this circuit configuration, only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used. A simplified space vector pulse width modulation scheme (SVPWM is also adopted to track the line current commands. A reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. This algorithm reduces the time required to calculate the switching time durations of voltage vectors. The simulation results have been presented to verify the validity and effectiveness of the proposed control strategy.

  8. A novel latch-up free SCR-LDMOS with high holding voltage for a power-rail ESD clamp

    Institute of Scientific and Technical Information of China (English)

    Pan Hongwei; Liu Siyang; Sun Weifeng

    2013-01-01

    The low snapback holding voltage of the SCR-LDMOS device makes it susceptible to latch-up failure,when used in power-rail ESD (electro-static discharge) clamp circuits.In order to eliminate latch-up risk,this work presents a novel SCR-LDMOS structure with an N-type implantation layer to achieve a 17 V holding voltage and a 5.2 A second breakdown current.The device has been validated using TLP measurement analysis and is applied to a power-rail ESD clamp in half-bridge driver ICs.

  9. Analytical evaluation of DC capacitor RMS current and voltage ripple in neutral-point clamped inverters

    Indian Academy of Sciences (India)

    K S GOPALAKRISHNAN; SANTOSH JANAKIRAMAN; SOUMITRA DAS; G NARAYANAN

    2017-06-01

    The sizing of the DC-link capacitor in a three-level inverter is based on the RMS current flowing through it. This paper analyses the DC-link capacitor RMS current in a neutral-point clamped (NPC) inverter and expresses the same as a function of modulation index, line-side current amplitude and power factor. Analytical closed-form expressions are derived for the capacitor RMS current for single-phase half-bridge,single-phase full-bridge and three-phase three-leg topologies of a three-level inverter. The worst-case capacitor current stress is determined for each topology based on the analytical expressions. Further, analytical expressions are derived for the RMS values of low-frequency and high-frequency capacitor currents. These expressions are then used to estimate voltage ripple across the DC capacitor for sinusoidally modulated three-phase NPC inverter. The analytical expressions for the RMS current and voltage ripple are validated experimentally over a wide range of operating points.

  10. Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter

    Directory of Open Access Journals (Sweden)

    Zulkifilie Bin Ibrahim

    2014-07-01

    Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM and Space Vector Pulse Width Modulation (SVPWM.  SPWM is the most simple modulation technique that can realize easily in analog circuit.  However, it has some drawbacks such as higher total harmonic distortion (THD, lower effective DC utilization and lower switching frequency. Space vector pulse width modulation (SVPWM is widely used because of their easier digital realization and better DC bus utilization and lower THD. The complexity is due to the difficulty in determining the reference vector location, on times calculation, and switching states selection. This paper presents a simple SVPWM algorithm for diode clamped three level inverters based on standard two-level SVPWM which can easily determine the location of reference vector, calculate the on-times, the selection of switching states. Three level diode clamped inverter (3LDCI using space vector modulation technique has been modeled and simulated using MATLAB/SIMULINK and Origin 6.1 with a passive R-L load that can be extended to any level. Simulation results are presented to verify the proposed SVPWM control in terms of THD. The results are compared with conventional sinusoidal pulse width modulation (SPWM where SVPWM shows better performance than SPWM in terms of THD.

  11. Studying mechanosensitive ion channels with an automated patch clamp

    NARCIS (Netherlands)

    Barthmes, Maria; Jose, Mac Donald F; Birkner, Jan Peter; Brüggemann, Andrea; Wahl-Schott, Christian; Kocer, Armagan

    2014-01-01

    Patch clamp electrophysiology is the main technique to study mechanosensitive ion channels (MSCs), however, conventional patch clamping is laborious and success and output depends on the skills of the operator. Even though automated patch systems solve these problems for other ion channels, they cou

  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...

  13. 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)

  14. Control Method of Three-level Neutral-point-clamped Inverter Based on Voltage Vector Diagram Partition

    Institute of Scientific and Technical Information of China (English)

    SONG Wen-xiang; YAO Gang; CHEN Chen; CHEN Guo-cheng

    2008-01-01

    A new modulation approach was presented for the control of neutral-point (NP) voltage variation in the three-level NP-clamped voltage source inverter, and the average NP current model was established based on vector diagram partition. Thus, theory base was built for balancing control of NP potential. Theoretical analysis and experimental results indicate that the proposed method for NP balancing control vector synthesizing concept based can make the average NP current zero, and do not influence NP potential within every sample period. The effectiveness of proposed research approach was verified by simulative and experimental results.

  15. [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 (clamping (g1: 111 mg/dl, g2: 125 mg/dl, g3: 173 mg/dl; pcord 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.

  16. Comparative Analysis of Different PWM Techniques to Reduce the Common Mode Voltage in Three-Level Neutral-Point-Clamped Inverters for Variable Speed Induction Drives

    Directory of Open Access Journals (Sweden)

    Bharati Raja

    2012-12-01

    Full Text Available This work presents the comparative study of the different PWM techniques to reduce the common-mode voltage (CMV at the output of neutral point diode clamped inverter for variable speed drives. Here the comparative study is done by the phase opposition disposed (POD, sinusoidal pulse width modulation (SPWM, phase disposition (PD, phase shift (PS space vector modulation (SVM techniques are proposed. A good trade-off between the quality of the output voltage and the partial magnitude of the CMV is achieved in this work. The scheme is proposed for three-level inverter. This work realizes the implementation of Three-level diode clamped MLI for three-phase (Y-Δ induction motor with the implementation of a space vector modulation technique without any additional control algorithm to reduce CMV within the range + Vdc/6. The Simulation with a 1HP induction motor drive system is setup in Matlab-2011b  and the same results validated effectively by hardware – FPGA-SPARTEN III processor and its shows that the CM voltage is effectively reduced and the maximum output voltage is not affected.  

  17. Control of gastric H,K-ATPase activity by cations, voltage and intracellular pH analyzed by voltage clamp fluorometry in Xenopus oocytes.

    Directory of Open Access Journals (Sweden)

    Katharina L Dürr

    Full Text Available Whereas electrogenic partial reactions of the Na,K-ATPase have been studied in depth, much less is known about the influence of the membrane potential on the electroneutrally operating gastric H,K-ATPase. In this work, we investigated site-specifically fluorescence-labeled H,K-ATPase expressed in Xenopus oocytes by voltage clamp fluorometry to monitor the voltage-dependent distribution between E(1P and E(2P states and measured Rb(+ uptake under various ionic and pH conditions. The steady-state E(1P/E(2P distribution, as indicated by the voltage-dependent fluorescence amplitudes and the Rb(+ uptake activity were highly sensitive to small changes in intracellular pH, whereas even large extracellular pH changes affected neither the E(1P/E(2P distribution nor transport activity. Notably, intracellular acidification by approximately 0.5 pH units shifted V(0.5, the voltage, at which the E(1P/E(2P ratio is 50∶50, by -100 mV. This was paralleled by an approximately two-fold acceleration of the forward rate constant of the E(1P→E(2P transition and a similar increase in the rate of steady-state cation transport. The temperature dependence of Rb(+ uptake yielded an activation energy of ∼90 kJ/mol, suggesting that ion transport is rate-limited by a major conformational transition. The pronounced sensitivity towards intracellular pH suggests that proton uptake from the cytoplasmic side controls the level of phosphoenzyme entering the E(1P→E(2P conformational transition, thus limiting ion transport of the gastric H,K-ATPase. These findings highlight the significance of cellular mechanisms contributing to increased proton availability in the cytoplasm of gastric parietal cells. Furthermore, we show that extracellular Na(+ profoundly alters the voltage-dependent E(1P/E(2P distribution indicating that Na(+ ions can act as surrogates for protons regarding the E(2P→E(1P transition. The complexity of the intra- and extracellular cation effects can be

  18. 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...... modulation and carrier-based PWM methods. Simulation and experimental results verify the validity and feasibility of the proposed new modulation strategy....

  19. Studying Voltage Transformer Ferroresonance

    Directory of Open Access Journals (Sweden)

    Hamid Radmanesh

    2012-09-01

    Full Text Available This study studies the effect of Circuit Breaker Shunt Resistance (CBSR, Metal Oxide Vaistor (MOV and Neutral earth Resistance (NR on the control of ferroresonance in the voltage transformer. It is expected that NR can controlled ferroresonance better than MOV and CBSR. Study has been done on a one phase voltage transformer rated 100 VA, 275 kV. The simulation results reveal that considering the CBSR and MOV exhibits a great mitigating effect on ferroresonance overvoltages, but these resistances cannot control these phenomena for all range of parameters. By applying NR to the system structure, ferroresonance has been controlled and its amplitude has been damped for all parameters values.

  20. Arterial Clamping Increases Central Renal Cryoablation Efficacy: An Animal Study

    DEFF Research Database (Denmark)

    Nonboe, Lasse Larsen; Nielsen, Tommy Kjaergaard; Høyer, Søren;

    2017-01-01

    INTRODUCTION: The minimally invasive treatment of small renal masses with cryoablation has become increasingly widespread during the past 15 years. Studies with long-term follow-up are beginning to emerge, showing good oncological control, however, tumors with a central and endophytic location seem...... to possess an increased risk of treatment failure. Such tumors are likely to be subjected to a high volume of blood giving thermal protection to the cancerous cells. Arterial clamping during freezing might reduce this effect but at the same time subject the kidney to ischemia. The aim of this study...... was to evaluate the effect of renal artery clamping during cryoablation in a porcine survival model. METHODS: Ten Danish Landrace pigs (approximately 40 kg) underwent bilateral laparoscopic cryoablation with clamping of the right renal artery during freezing. The cryoablation consisted of a standard double...

  1. 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...... of the load is close to unity. In this paper, a new single-inductor multi-output dc/dc converter is proposed that can control the dc-link voltages of a single-phase diode-clamped inverter asymmetrically to achieve voltage quality enhancement. The circuit of the presented converter is explained and the main...... equations are developed. A control strategy is proposed and explained in details. To validate the versatility of the proposed combination of the suggested dc–dc converter and the asymmetrical four-level diode-clamped inverter (ADCI), simulations and experiments have been directed. It is concluded...

  2. Pulse and Trapezoidal Voltage Clamp Applied To Jurkat Cells: A T- Lymphocyte Cell Line

    Science.gov (United States)

    1993-04-01

    clamp. (Upward deflection represents depolarization). Low frequency oscillations are clearly visible. Such oscillations have been described by Maltsev ...1952. (8) Maltsev , V. A. Oscillating and triggering properties of T cell membrane potential. Imun. Lett. 26:277-282, 1990. 13 (9) Gallin, E. K

  3. Voltage-clamp predictions by gompertz kinetics model relating squid-axon Na+-gating and ionic currents.

    Science.gov (United States)

    Easton, Dexter M

    2005-10-01

    Gompertz kinetics is a simple, realistic, accurate, and computationally parsimonious alternative for prediction of macroscopic changes in Na+ conductance during voltage clamp. Conductance delay and time course depend on initial amplitudes and decay rates of surrogates for the macroscopic gating currents. The model is tested by the fit to published data of other authors. The proposed physical basis for the model is that membrane potential perturbation triggers motion of charged "gating" components of the axon membrane at rapid (activating) and at slow (inactivating) rates. The resulting distortion increases and more slowly diminishes the probability that conduction channels will be open.

  4. 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.

  5. An operational amplifier B1404UD1A-1 in the patch-clamp current-to-voltage converter.

    Science.gov (United States)

    Korzun, A M; Rozinov, S V; Abashin, G I

    1997-01-01

    The applicability of the home-made operational amplifier B1404UD1A-1 in a patch-clamp current-to-voltage converter was analyzed. Its parameters (background noise, input bias current, and gain-bandwidth product) were estimated. Schematic solutions and practical recommendations for the use of this amplifier in a current-to-voltage converter were given. Based on the background noise and frequency parameters of the converter, we found that this device can be used for measuring ion channel currents with a high sensitivity and within a broad frequency range (0.055 pA, to 1 kHz; 0.4 pA, to 10 kHz). An example of the converter application in experiments is given.

  6. Carrier-Based Common Mode Voltage Control Techniques in Three-Level Diode-Clamped Inverter

    Directory of Open Access Journals (Sweden)

    Pradyumn Chaturvedi

    2012-01-01

    Full Text Available Switching converters are used in electric drive applications to produce variable voltage, variable frequency supply which generates harmful large dv/dt and high-frequency common mode voltages (CMV. Multilevel inverters generate lower CMV as compared to conventional two-level inverters. This paper presents simple carrier-based technique to control the common mode voltages in multilevel inverters using different structures of sine-triangle comparison method such as phase disposition (PD, phase opposition disposition (POD by adding common mode voltage offset signal to actual reference voltage signal. This paper also presented the method to optimize the magnitude of this offset signal to reduce CMV and total harmonic distortion in inverter output voltage. The presented techniques give comparable performance as obtained in complex space vector-based control strategy, in terms of number of commutations, magnitude, and rate of change of CMV and harmonic profile of inverter output voltage. Simulation and experimental results presented confirm the effectiveness of the proposed techniques to control the common mode voltages.

  7. 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...

  8. A numerical approach to ion channel modelling using whole-cell voltage-clamp recordings and a genetic algorithm.

    Directory of Open Access Journals (Sweden)

    Meron Gurkiewicz

    2007-08-01

    Full Text Available The activity of trans-membrane proteins such as ion channels is the essence of neuronal transmission. The currently most accurate method for determining ion channel kinetic mechanisms is single-channel recording and analysis. Yet, the limitations and complexities in interpreting single-channel recordings discourage many physiologists from using them. Here we show that a genetic search algorithm in combination with a gradient descent algorithm can be used to fit whole-cell voltage-clamp data to kinetic models with a high degree of accuracy. Previously, ion channel stimulation traces were analyzed one at a time, the results of these analyses being combined to produce a picture of channel kinetics. Here the entire set of traces from all stimulation protocols are analysed simultaneously. The algorithm was initially tested on simulated current traces produced by several Hodgkin-Huxley-like and Markov chain models of voltage-gated potassium and sodium channels. Currents were also produced by simulating levels of noise expected from actual patch recordings. Finally, the algorithm was used for finding the kinetic parameters of several voltage-gated sodium and potassium channels models by matching its results to data recorded from layer 5 pyramidal neurons of the rat cortex in the nucleated outside-out patch configuration. The minimization scheme gives electrophysiologists a tool for reproducing and simulating voltage-gated ion channel kinetics at the cellular level.

  9. 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-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....

  10. 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...

  11. Advanced patch-clamp techniques and single-channel analysis

    NARCIS (Netherlands)

    Biskup, B; Elzenga, JTM; Homann, U; Thiel, G; Wissing, F; Maathuis, FJM

    1999-01-01

    Much of our knowledge of ion-transport mechanisms in plant cell membranes comes from experiments using voltage-clamp. This technique allows the measurement of ionic currents across the membrane, whilst the voltage is held under experimental control. The patch-clamp technique was developed to study t

  12. Analysis of the effects of calcium or magnesium on voltage-clamp currents in perfused squid axons bathed in solutions of high potassium.

    Science.gov (United States)

    Rojas, E; Taylor, R E; Atwater, I; Bezanilla, F

    1969-10-01

    Isolated axons from the squid, Dosidicus gigas, were internally perfused with potassium fluoride solutions. Membrane currents were measured following step changes of membrane potential in a voltage-clamp arrangement with external isosmotic solution changes in the order: potassium-free artificial seawater; potassium chloride; potassium chloride containing 10, 25, 40 or 50, mM calcium or magnesium; and potassium-free artificial seawater. The following results suggest that the currents measured under voltage clamp with potassium outside and inside can be separated into two components and that one of them, the predominant one, is carried through the potassium system. (a) Outward currents in isosmotic potassium were strongly and reversibly reduced by tetraethylammonium chloride. (b) Without calcium or magnesium a progressive increase in the nontime-dependent component of the currents (leakage) occurred. (c) The restoration of calcium or magnesium within 15-30 min decreases this leakage. (d) With 50 mM divalent ions the steady-state current-voltage curve was nonlinear with negative resistance as observed in intact axons in isosmotic potassium. (e) The time-dependent components of the membrane currents were not clearly affected by calcium or magnesium. These results show a strong dependence of the leakage currents on external calcium or magnesium concentration but provide no support for the involvement of calcium or magnesium in the kinetics of the potassium system.

  13. 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

    much smaller effects. At comparable concentrations, it depolarized Vm by a few millivolts. Neither agonist had significant effects on intracellular Ca2+. CONCLUSIONS: This study provides the first direct evidence that adrenergic stimulation, namely, that of beta-adrenoceptors, controls ion transport....... 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...... in pancreatic ducts. Similar to secretin, isoproterenol stimulation leads to opening of luminal Cl- channels, and HCO3- enters the lumen in exchange for Cl-....

  14. Effect of terfenadine and pentamidine on the HERG channel and its intracellular trafficking: combined analysis with automated voltage clamp and confocal microscopy.

    Science.gov (United States)

    Tanaka, Hikaru; Takahashi, Yukiko; Hamaguchi, Shogo; Iida-Tanaka, Naoko; Oka, Takayuki; Nishio, Masato; Ohtsuki, Atsushi; Namekata, Iyuki

    2014-01-01

    The effects of terfenadine and pentamidine on the human ether-a-go-go related gene (hERG) channel current and its intracellular trafficking were evaluated. Green fluorescent protein (GFP)-linked hERG channels were expressed in HEK293 cells, and the membrane current was measured by an automated whole cell voltage clamp system. To evaluate drug effects on channel trafficking to the cell membrane, the fraction of channel present on the cell membrane was quantified by current measurement after drug washout and confocal microscopy. Terfenadine directly blocked the hERG channel current but had no effect on trafficking of hERG channels to the cell membrane after application in culture medium for 2 d. In contrast, pentamidine had no direct effect on the hERG channel current but reduced trafficking of hERG channels. The two drugs inhibited hERG channel function through different mechanisms: terfenadine through direct channel blockade and pentamidine through inhibition of channel trafficking to the cell membrane. Combined use of automated voltage clamp and confocal microscopic analyses would provide insights into the mechanisms of drug-induced QT-prolongation and arrhythmogenesis.

  15. 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...

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

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2014-01-01

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

  17. Ion channelopathies in human induced pluripotent stem cell derived cardiomyocytes: a dynamic clamp study with virtual IK1

    Directory of Open Access Journals (Sweden)

    Rosalie M.E. Meijer van Putten

    2015-02-01

    Full Text Available Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs are widely used in studying basic mechanisms of cardiac arrhythmias that are caused by ion channelopathies. Unfortunately, the action potential profile of hiPSC-CMs—and consequently the profile of individual membrane currents active during that action potential—differs substantially from that of native human cardiomyocytes, largely due to almost negligible expression of the inward rectifier potassium current (IK1.In the present study, we attempted to ‘normalize’ the action potential profile of our hiPSC-CMs by inserting a voltage dependent in silico IK1 into our hiPSC-CMs, using the dynamic clamp configuration of the patch clamp technique. Recordings were made from single hiPSC-CMs, using the perforated patch clamp technique at physiological temperature.We assessed three different models of IK1, with different degrees of inward rectification, and systematically varied the magnitude of the inserted IK1. Also, we modified the inserted IK1 in order to assess the effects of loss- and gain-of-function mutations in the KCNJ2 gene, which encodes the Kir2.1 protein that is primarily responsible for the IK1 channel in human ventricle.For our experiments, we selected spontaneously beating hiPSC-CMs, with negligible IK1 as demonstrated in separate voltage clamp experiments, which were paced at 1 Hz. Upon addition of in silico IK1 with a peak outward density of 4–6 pA/pF, these hiPSC-CMs showed a ventricular-like action potential morphology with a stable resting membrane potential near −80 mV and a maximum upstroke velocity >150 V/s (n=9. Proarrhythmic action potential changes were observed upon injection of both loss-of-function and gain-of-function IK1, as associated with Andersen-Tawil syndrome type 1 and short QT syndrome type 3, respectively (n=6.We conclude that injection of in silico IK1 makes the hiPSC-CM a more reliable model for investigating mechanisms underlying

  18. In vivo patch clamp recording technique in the study of neurophysiology

    Institute of Scientific and Technical Information of China (English)

    Lan-Wei CUI; Yu-Rong LI

    2006-01-01

    The patch clamp recording technique in vivois a blind patch clamp recording methods to record the current of the spinal or cereral neurons of anaesthesia ( or awake) animals. This technique can be used to study the synaptic function and plasticity in central nervous system in vivoin order to understand the physiological properties of the ion channels from an integrated point of view. The advantage of this technique have already presented itself in the study of the synaptic transmission and nervous network. Nowadays, in vivo patch whole-cell recording technique in combination with other techniques is becoming a common method in the research fields.

  19. To clamp or not to clamp late?

    Directory of Open Access Journals (Sweden)

    Nicoletta Iacovidou

    2013-04-01

    Full Text Available When resuscitating a neonate, one encounters controversial issues and a great deal of confusion. These issues include the question as to when should the umbilical cord be clamped. Clamping and cutting the umbilical cord at birth is the oldest intervention in humans. Even though many aspects of the timing for cord clamping have been clarified, some questions still remain unanswered. If delayed cord clamping is to become a standard approach which timing is the optimal? And depending on the mode of delivery should timing be the same or different for normal vaginal delivery or for caesarean section? What about  the compromised neonate, or the very preterm one? We have more questions than answers. More randomized controlled studies are needed in normal and pathologic neonates, in order to address these questions, before we practice delayed cord clamping with safety for the babies and the mothers.

  20. Sites and mechanisms of antibiotic-induced neuromuscular block: a pharmacological analysis using quantal content, voltage clamped end-plate currents and single channel analysis.

    Science.gov (United States)

    Fiekers, J F

    1999-01-01

    Since the original observation of Vital Brazil and Corrado (1957) concerning the antibiotic induced neuromuscular block produced by streptomycin, there has been considerable interest in the mechanisms responsible for not only neuromuscular block but also the effects of antibiotics on different systems. We used the voltage clamped end-plate of transacted skeletal muscle to examine the concentration-dependent actions of several groups of antibiotics. The aminoglycoside antibiotics, neomycin and streptomycin, were both more effective at reducing quantal release of acetylcholine (ACh) than interacting with the postjunctional ACh receptor-channel complex. Neomycin was approximately 10 X more potent prejunctionally than streptomycin and the prejunctional effects of each antibiotic were reversed competitively by raising extracellular calcium. Both neomycin and streptomycin also had postjunctional actions at higher concentrations. Neomycin interacted with the open state of the ACh receptor ion channel complex while streptomycin blocks the ACh receptor. The lincosamide antibiotics, lincomycin and clindamycin produced their neuromuscular block postjunctionally by interacting with the open state of the ACh-receptor channel complex. Clindamycin is approximately 20 X more effective at blocking the open channel than was lincomycin. Using cell attached patch clamp recordings in cultured rat myotubes, we demonstrated a lincosamide-induced block of open ion channels with clindamycin having a much slower unblocking rate than lincomycin. Using epimers of the lincosamides, we demonstrated that lipophilicity of the molecule, rather than stereochemical considerations, is important for open channel blockade affecting primarily the "off" rate of channel blocking. This mechanism appears important for not only the lincosamide antibiotics but also for the postjunctional actions of the aminoglycoside antibiotics, particularly neomycin.

  1. Comparison of herniorrhaphy versus clamping of umbilical hernias in horses: a retrospective study of 93 cases (1982-1994).

    OpenAIRE

    1996-01-01

    Many uncomplicated umbilical hernias have been managed successfully in foals by the application of a hernia clamp. Isolated reports of complications following clamp application have led some authors to suggest that it is an unsuitable method of treatment. Little information has been published comparing the complication rates associated with the use of hernia clamps and herniorrhaphy in the treatment of umbilical hernias. The purpose of this retrospective study was to report the characteristic...

  2. [Delayed umbilical cord clamping in preterm infants born before 37 weeks of gestation: A prospective observational study].

    Science.gov (United States)

    Dicky, O; Ehlinger, V; Guyard-Boileau, B; Assouline, C; Arnaud, C; Casper, C

    2017-02-01

    Many international studies have demonstrated that delayed umbilical cord clamping reduces neonatal morbidity. However, in France, delayed umbilical cord clamping is still not performed in many neonatal units. The aims of this study were to evaluate the feasibility of developing a protocol of delayed umbilical cord clamping in the maternity ward of the Toulouse university hospital and to evaluate the impact of this new protocol on neonatal mortality. We conducted a prospective observational study including 123 preterm infants born before 37 weeks of gestation between June 2012 and June 2013 and hospitalized at birth. Delayed cord clamping was performed for at least 30s after birth; otherwise, it was evaluated as early cord clamping. We excluded twin-to-twin transfusion syndrome, congenital abnormalities, alloimmunization, and perinatal asphyxia. We analyzed the reasons why delayed umbilical cord clamping was not performed and then neonatal morbidity in our population. Delayed umbilical cord clamping was performed on 79 infants and 44 infants had early umbilical cord clamping. The two groups had similar baseline characteristics. Preterm infants in the delayed cord-clamping group had a higher level of hemoglobin during the first 24h of life (17.9g/dL versus 16.6g/dL, P=0.005), fewer of them required transfusion (14% versus 35%, P=0.03), and fewer presented late-onset sepsis (8% versus 26%, P=0.02) or bronchopulmonary dysplasia (9% versus 26%, P=0.03). There was no statistically significant increase of hyperbilirubinemia requiring phototherapy. Implanting a new protocol of delayed umbilical cord clamping in our maternity ward proved to be possible without difficulty. The advantages of delayed umbilical cord clamping were observed in this prospective study. Today, delayed cord clamping has become a common practice in our maternity unit. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  3. How Does Patch Clamp Work?--An easy approach to understanding patch clamp mechanism

    Institute of Scientific and Technical Information of China (English)

    关兵才; 李之望

    2003-01-01

    In order to help patch clamp users,most of whom are not good enough at electrics and electronics,to understandthe complicated principles of patch clamp technique,we present a readily accessible explanation of patch clamp mechanism,in-cluding basic analysis of membrane currents under voltage clamp,achievement of voltage clamp and current recording,capaci-tance compensation,series resistance compensation,voltage offset correction,leak subtraction and current clamp,based on ourworking and teaching experience and with the aid of some useful formulae.

  4. Unloaded speed of shortening in voltage-clamped intact skeletal muscle fibers from wt, mdx, and transgenic minidystrophin mice using a novel high-speed acquisition system.

    Science.gov (United States)

    Friedrich, O; Weber, C; von Wegner, F; Chamberlain, J S; Fink, R H A

    2008-06-01

    Skeletal muscle unloaded shortening has been indirectly determined in the past. Here, we present a novel high-speed optical tracking technique that allows recording of unloaded shortening in single intact, voltage-clamped mammalian skeletal muscle fibers with 2-ms time resolution. L-type Ca(2+) currents were simultaneously recorded. The time course of shortening was biexponential: a fast initial phase, tau(1), and a slower successive phase, tau(2,) with activation energies of 59 kJ/mol and 47 kJ/mol. Maximum unloaded shortening speed, v(u,max), was faster than that derived using other techniques, e.g., approximately 14.0 L(0) s(-1) at 30 degrees C. Our technique also allowed direct determination of shortening acceleration. We applied our technique to single fibers from C57 wild-type, dystrophic mdx, and minidystrophin-expressing mice to test whether unloaded shortening was affected in the pathophysiological mechanism of Duchenne muscular dystrophy. v(u,max) and a(u,max) values were not significantly different in the three strains, whereas tau(1) and tau(2) were increased in mdx fibers. The results were complemented by myosin heavy and light chain (MLC) determinations that showed the same myosin heavy chain IIA profiles in the interossei muscles from the different strains. In mdx muscle, MLC-1f was significantly increased and MLC-2f and MLC-3f somewhat reduced. Fast initial active shortening seems almost unaffected in mdx muscle.

  5. An observational study of umbilical cord clamping practices of maternity care providers in a tertiary care center.

    Science.gov (United States)

    Hutton, Eileen K; Stoll, Kathrin; Taha, Natalie

    2013-03-01

    Severing the umbilical cord at birth is likely the oldest intervention, the timing of which remains fraught with controversy. Emerging evidence suggests benefit in delaying cord clamping for both term and preterm infants. The objective of this study was to investigate actual cord clamping time and circumstances at a large tertiary care center in Canada. We used a stopwatch to time the interval from the time the infant was born as far as the umbilicus until the time that the umbilical cord was clamped before cutting. We reported on timing of the umbilical cord clamping overall and by practitioner group (obstetrician, midwife, and family practitioner). A total of 98 women and their practitioners consented to be observed at the British Columbia Women's Hospital and Health Center, Vancouver, Canada. More than one-half (56.2%) of all infants had their umbilical cord clamped within 15 seconds. The median (5th, 95th percentile) clamping time in seconds for the full sample was 12 (4, 402) with practitioner subgroups as follows: obstetricians (12 [3, 107]), family physicians (19 [6, 325]), and midwives (81 [6, undefined]). The median clamping time was likely to be longer when the birth occurred spontaneously, no umbilical cord blood was collected, and no birth or neonatal complications occurred. In our sample taken in 2006 to 2007, most infants had umbilical cords clamped immediately after the birth, with more than one-half clamped within 15 seconds of birth. Since the time of our study, delayed umbilical cord clamping for the healthy term newborn has become a part of recommended management of third stage of labor and resuscitation guidelines. It would be informative to repeat a study like this one to determine compliance with the current standards of care. © 2013, Copyright the Authors Journal compilation © 2013, Wiley Periodicals, Inc.

  6. Study of transmembrane La3+ movement in rat ventricular myocytes by the patch-clamp technique

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We have studied transmembrane La3+ movement in rat ventricular myocytes for the first time by using the whole-cell patch-clamp recording mode. La3+ (0.01-5.0 mmol/L) could not bring out inward currents through the L-type calcium channel in rat ventricular myocytes, while it could enter the cells by the same way carried by 1μmol/L ionomycin. When the outward Na+ concentration gradient is formed, La3+ can enter the cells via Na-Ca exchange, and the exchange currentsincrease with the increase of external La3+ concentrations. But compared with Na-Ca exchange currents in the same concentration, the former is only 14%-38% of the latter. The patch-clamp experiment indicates that La3+ normally can not enter ventricular myocytes through L-type calcium channel, but it can enter the cells via Na-Ca exchange.

  7. Planar patch-clamp force microscopy on living cells

    Energy Technology Data Exchange (ETDEWEB)

    Pamir, Evren [Center for Nano Science, Ludwig-Maximilians University, Amalienstr 54, 80799 Munich (Germany); George, Michael; Fertig, Niels [Nanion Technologies GmbH, Erzgiessereistr. 4, 80335 Munich (Germany); Benoit, Martin [Center for Nano Science, Ludwig-Maximilians University, Amalienstr 54, 80799 Munich (Germany)], E-mail: martin.benoit@physik.uni-muenchen.de

    2008-05-15

    Here we report a new combination of the patch-clamp technique with the atomic force microscope (AFM). A planar patch-clamp chip microstructured from borosilicate glass was used as a support for mechanical probing of living cells. The setup not only allows for immobilizing even a non-adherent cell for measurements of its mechanical properties, but also for simultaneously measuring the electrophysiological properties of a single cell. As a proof of principle experiment we measured the voltage-induced membrane movement of HEK293 and Jurkat cells in the whole-cell voltage clamp configuration. The results of these measurements are in good agreement with previous studies. By using the planar patch-clamp chip for immobilization, the AFM not only can image non-adhering cells, but also gets easily access to an electrophysiologically controlled cellular probe at low vibrational noise.

  8. Technical feasibility study of Voltage Optimization Unit

    DEFF Research Database (Denmark)

    Hu, Junjie; Marinelli, Mattia; Coppo, Massimiliano

    transformer with OLTC per phase is necessary and valuable. The main conclusion is that power distribution transformer with OLTC control on each phase can significantly improve the PV hosting capacity in the analyzed unbal-anced scenarios. To investigate the verification problem, a simulation study...... is performed using the soft-wares DigSilent PowerFactory and Matlab. In this simulation study, a real low voltage network from Dong Eldistribution is modeled in Powerfactory. The measured data of the real low voltage network is analyzed and the resulting loading profiles including active and reactive power...... are used as load basics for the analysis. In term of PV genera-tion profiles, a realistic PV output power is assumed. Four relevant indicies such as phase neutral voltage, netural potential voltage, unbalanced factor (VUF), and power losses are evaluated in the present study. The simulation tests include...

  9. 一种新型自均压二极管钳位级联有源滤波器%A Novel Voltage Self-balance Diode-clamped Cascaded Multilevel Active Power Filter

    Institute of Scientific and Technical Information of China (English)

    高聪哲; 姜新建; 李永东

    2012-01-01

    A novel diode-clamped cascaded multilevel converter topology is proposed. The half bridge cascade cell is added a clamping diode to the DC-link capacitor, and it may provide an energy channel clamping in single direction for capacitor voltage. Via the clamping diodes, only the top and bottom cells of a phase arm need to be controlled to realize each cell' s capacitors voltage balance. Therefore, the DC-link voltage sensors of a phase arm are reduced to two, much less than that of traditional cascaded converter. A three-phase multilevel active power filter (APF) topology based on the proposed diode clamped cascaded multilevel converter topology is provided, and its control strategy is presented as well. A simulation model and an experiment prototype of seven-level diode-clamped cascaded multilevel APF are built. The simulation and experiment results show that the novel cascaded multilevel converter topology has good performance in voltage selbbalance control and harmonics compensation, and the control algorithm is easy and feasible.%提出一种新型二极管钳位级联多电平拓扑,在半桥单元拓扑上增加钳位二极管,为直流电容提供单向钳位通路。在该拓扑中,只需对阀体两端单元的直流电压进行控制就可实现均压控制,且每相阀体只需2个直流电压传感器,结构简单。将拓扑拓展到三相结构,提出了二极管钳位多电平有源滤波器(APF)拓扑及其控制方法。搭建了7电平二极管钳位多电平APF仿真模型和实验样机。实验结果表明,该拓扑自均压控制和谐波补偿效果良好,控制算法简易、可行。

  10. On the use of Cu:Be clamp cells in magnetization and neutron scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    Pfleiderer, C [Physikalisches Institut, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany); Huxley, A D [DRFMC-SPSMS, CEA Grenoble, F-38054 Grenoble Cedex 9 (France); Hayden, S M [HH Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

    2005-10-12

    The use of miniature clamp cells made of Cu:Be for magnetization and neutron scattering studies in the medium pressure range is reviewed by giving recent results achieved in studies of UGe{sub 2}, MnSi and ZrZn{sub 2}. The experiments reviewed here establish in particular that small samples can be studied rather well at high pressures using a variety of different techniques, notably conventional diffraction, cold and thermal neutron triple axes and small-angle neutron scattering.

  11. Patch clamp studies of human sperm under physiological ionic conditions reveal three functionally and pharmacologically distinct cation channels.

    Science.gov (United States)

    Mansell, S A; Publicover, S J; Barratt, C L R; Wilson, S M

    2014-05-01

    Whilst fertilizing capacity depends upon a K(+) conductance (GK) that allows the spermatozoon membrane potential (Vm) to be held at a negative value, the characteristics of this conductance in human sperm are virtually unknown. We therefore studied the biophysical/pharmacological properties of the K(+) conductance in spermatozoa from normal donors held under voltage/current clamp in the whole cell recording configuration. Our standard recording conditions were designed to maintain quasi-physiological, Na(+), K(+) and Cl(-) gradients. Experiments that explored the effects of ionic substitution/ion channel blockers upon membrane current/potential showed that resting Vm was dependent upon a hyperpolarizing K(+) current that flowed via channels that displayed only weak voltage dependence and limited (∼7-fold) K(+) versus Na(+) selectivity. This conductance was blocked by quinidine (0.3 mM), bupivacaine (3 mM) and clofilium (50 µM), NNC55-0396 (2 µM) and mibefradil (30 µM), but not by 4-aminopyridine (2 mM, 4-AP). Progesterone had no effect upon the hyperpolarizing K(+) current. Repolarization after a test depolarization consistently evoked a transient inward 'tail current' (ITail) that flowed via a second population of ion channels with poor (∼3-fold) K(+) versus Na(+) selectivity. The activity of these channels was increased by quinidine, 4-AP and progesterone. Vm in human sperm is therefore dependent upon a hyperpolarizing K(+) current that flows via channels that most closely resemble those encoded by Slo3. Although 0.5 µM progesterone had no effect upon these channels, this hormone did activate the pharmacologically distinct channels that mediate ITail. In conclusion, this study reveals three functionally and pharmacologically distinct cation channels: Ik, ITail, ICatSper.

  12. 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...

  13. 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

    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...

  14. 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.

  15. 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

    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......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...... a maximum number of output voltage levels by preserving the adjacent switching vectors between voltage levels. Hence, a 15-level hybrid converter can be attained with a minimum number of power components. A comparative study has been carried out to present high performance of the proposed configuration...

  16. Study of Dynamic Behavior of Multilayered Clamped Composite Skewed Hypar Shell Roofs under Impact Load

    Directory of Open Access Journals (Sweden)

    Sanjoy Das Neogi

    2013-01-01

    Full Text Available With advancement in the field of structural engineering, hunt for smarter materials has channelised the research towards the application of composite material. It is the high specific weight and specific stiffness of this material that have drawn the interest of different industrial sectors. Civil engineers also picked up composites to use it as a roofing material. Laminated composite shells, which can cover large column-free area and reduces dead weight of structure, show vulnerability under sudden impact due to their low transverse shear resistances. This study utilises finite element tool to investigate the dynamic response of a multilayered laminated composite hypar shells for fully clamped boundary condition. This class of shells is unique in a sense that the curvature has only the radius of cross curvature and these shells do not admit easy closed form solution particularly when the boundary conditions are complicated. Contact behavior of impactor and impacted mass has been modeled by modified Hertzian contact law and time-dependent equations are solved using Newmark’s time integration technique. Basic aim is to analyse the shell for symmetrically placed multilayered angle and cross ply lamination under different impact velocities.

  17. 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

    investigates the loss and thermal performances of a 10 MW 3L-NPC wind power inverter undergoing Low Voltage Ride Through (LVRT) operation. A series of new space vector modulation methods are then proposed to relocate the thermal loading among the power switching devices. It is concluded that, with the proposed...

  18. 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.

  19. A New Preparation of Pancreatic Ducts for Patch-Clamp Studies

    DEFF Research Database (Denmark)

    Novak, Ivana; Hug, M.J.

    1995-01-01

    parameters, monitored with the whole-cell patch-clamp method, and those in isolated perfused ducts, monitored with the conventional microelectrodes [Novak I, Greger R: Pflügers Arch 1988;411:58-68, 546-553], are comparable. Similar conclusion can be made about the calcium measurements [Hug M, et al: Pflügers...

  20. 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

  1. 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

    2017-03-20

    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 cord clamping group compared with the other two groups. The disulfide/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.

  2. Properties of the nucleo-olivary pathway: an in vivo whole-cell patch clamp study.

    Directory of Open Access Journals (Sweden)

    Paolo Bazzigaluppi

    Full Text Available The inferior olivary nucleus (IO forms the gateway to the cerebellar cortex and receives feedback information from the cerebellar nuclei (CN, thereby occupying a central position in the olivo-cerebellar loop. Here, we investigated the feedback input from the CN to the IO in vivo in mice using the whole-cell patch-clamp technique. This approach allows us to study how the CN-feedback input is integrated with the activity of olivary neurons, while the olivo-cerebellar system and its connections are intact. Our results show how IO neurons respond to CN stimulation sequentially with: i a short depolarization (EPSP, ii a hyperpolarization (IPSP and iii a rebound depolarization. The latter two phenomena can also be evoked without the EPSPs. The IPSP is sensitive to a GABA(A receptor blocker. The IPSP suppresses suprathreshold and subthreshold activity and is generated mainly by activation of the GABA(A receptors. The rebound depolarization re-initiates and temporarily phase locks the subthreshold oscillations. Lack of electrotonical coupling does not affect the IPSP of individual olivary neurons, nor the sensitivity of its GABA(A receptors to blockers. The GABAergic feedback input from the CN does not only temporarily block the transmission of signals through the IO, it also isolates neurons from the network by shunting the junction current and re-initiates the temporal pattern after a fixed time point. These data suggest that the IO not only functions as a cerebellar controlled gating device, but also operates as a pattern generator for controlling motor timing and/or learning.

  3. Note: High-efficiency energy harvester using double-clamped piezoelectric beams

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yingmei; Wu, Xuan; Parmar, Mitesh; Lee, Dong-weon, E-mail: mems@jnu.ac.kr [MEMS and Nanotechnology Laboratory, School of Mechanical Systems Engineering, Chonnam National University, Gwangju (Korea, Republic of)

    2014-02-15

    In this study, an improvement in energy conversion efficiency has been reported, which is realized by using a double-clamped piezoelectric beam, based on uniaxial stretching strain. The buckling mechanism is applied to maximize axial stress in the double-clamped beam. The voltage generated by using the double-clamped piezoelectric beam is higher than that generated by using other conventional structures, such as bending cantilevers coated/sandwiched with piezoelectric film, which is proven both theoretically and experimentally. The power generation efficiency is enhanced by further optimizing the double-clamped structure. The optimized high-efficiency energy harvester utilizing double-clamped piezoelectric beams generates a peak output power of 80 μW, under an acceleration of 0.1g.

  4. Note: high-efficiency energy harvester using double-clamped piezoelectric beams.

    Science.gov (United States)

    Zheng, Yingmei; Wu, Xuan; Parmar, Mitesh; Lee, Dong-weon

    2014-02-01

    In this study, an improvement in energy conversion efficiency has been reported, which is realized by using a double-clamped piezoelectric beam, based on uniaxial stretching strain. The buckling mechanism is applied to maximize axial stress in the double-clamped beam. The voltage generated by using the double-clamped piezoelectric beam is higher than that generated by using other conventional structures, such as bending cantilevers coated/sandwiched with piezoelectric film, which is proven both theoretically and experimentally. The power generation efficiency is enhanced by further optimizing the double-clamped structure. The optimized high-efficiency energy harvester utilizing double-clamped piezoelectric beams generates a peak output power of 80 μW, under an acceleration of 0.1g.

  5. 多电平变换器直流侧电压平衡控制电路%DC Bus Capacitor Voltage Balancing Circuits in Diode-Clamped Multilevel Converter

    Institute of Scientific and Technical Information of China (English)

    丁娜; 舒泽亮

    2014-01-01

    为解决二极管箝位型多电平变换器直流侧电容电压不平衡的问题,设计了一种带二级辅助电感的平衡控制电路,通过简单控制可以平衡多电平变换器直流侧所有电容的电压。在分析电路结构和控制原理的基础上,从能量转换的角度出发,给出了辅助电感参数选择的范围。以五电平变换器为研究对象,建立了Matlab/Simulink仿真模型,搭建了实验样机,对比分析了本文平衡电路与传统一级平衡控制电路的电容电压平衡特性。实验结果表明,当二级辅助电路工作时,所有直流侧电容电压在20 ms内达到平衡,电容电压的纹波小于3%。%In order to solve the imbalance of DC bus capacitor voltages in the diode-clamped multilevel converter,a balancing circuit with two-layer auxiliary inductors was designed. With this circuit,the voltages of all the DC-side capacitors in the multilevel converter can be balanced by a simple control. On the basis of analysis of the circuit structure and control principle,the ranges of inductor parameters were analyzed from the viewpoint of energy conversion. Taking a five-level converter as an example,a Matlab/Simulink simulation model and an experimental prototype were built,and the balance characteristics of DC bus capacitor voltages were compared between the proposed two-layer auxiliary circuit and the traditional one-layer circuit. Experimental results verify that the proposed two-layer circuit could effectively balance all the DC bus capacitor voltages within 20 ms,and the capacitor voltage ripple was less than 3%.

  6. Immunologic and infectious consequences of immediate versus delayed umbilical cord clamping in premature infants: a prospective, randomized, controlled study.

    Science.gov (United States)

    Kugelman, Amir; Borenstein-Levin, Liron; Kessel, Aharon; Riskin, Arieh; Toubi, Elias; Bader, David

    2009-01-01

    To evaluate the immunologic and infectious consequences of delayed versus immediate cord clamping in premature infants (cord clamping (ICC) at 5-10 s and 30 infants to delayed cord clamping (DCC), at 30-45 s (14 and 15 infants in each group were cord clamping did not affect the immunologic or the infectious status of infants born at <35 weeks during the neonatal period.

  7. Implementing dynamic clamp with synaptic and artificial conductances in mouse retinal ganglion cells.

    Science.gov (United States)

    Huang, Jin Y; Stiefel, Klaus M; Protti, Dario A

    2013-05-16

    Ganglion cells are the output neurons of the retina and their activity reflects the integration of multiple synaptic inputs arising from specific neural circuits. Patch clamp techniques, in voltage clamp and current clamp configurations, are commonly used to study the physiological properties of neurons and to characterize their synaptic inputs. Although the application of these techniques is highly informative, they pose various limitations. For example, it is difficult to quantify how the precise interactions of excitatory and inhibitory inputs determine response output. To address this issue, we used a modified current clamp technique, dynamic clamp, also called conductance clamp (1, 2, 3) and examined the impact of excitatory and inhibitory synaptic inputs on neuronal excitability. This technique requires the injection of current into the cell and is dependent on the real-time feedback of its membrane potential at that time. The injected current is calculated from predetermined excitatory and inhibitory synaptic conductances, their reversal potentials and the cell's instantaneous membrane potential. Details on the experimental procedures, patch clamping cells to achieve a whole-cell configuration and employment of the dynamic clamp technique are illustrated in this video article. Here, we show the responses of mouse retinal ganglion cells to various conductance waveforms obtained from physiological experiments in control conditions or in the presence of drugs. Furthermore, we show the use of artificial excitatory and inhibitory conductances generated using alpha functions to investigate the responses of the cells.

  8. 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.

  9. DFIG turbine representation for small signal voltage control studies

    DEFF Research Database (Denmark)

    Garcia, Jorge Martinez; Kjær, Philip Carne; Teodorescu, Remus

    2010-01-01

    This paper addresses the representation of a wind power plant, based on wound rotor asynchronous generators, with a centralized voltage controller, by an equivalent transfer function, valid for small signal voltage control studies. This representation allows to investigate the influence of the ce...

  10. 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.

  11. Photovoltaic panel clamp

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Malcolm P.; Mittan, Margaret Birmingham; Miros, Robert H. J.; Stancel, Robert

    2013-03-19

    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.

  12. Photovoltaic panel clamp

    Science.gov (United States)

    Mittan, Margaret Birmingham; Miros, Robert H. J.; Brown, Malcolm P.; Stancel, Robert

    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. The RFC clamp loader: structure and function.

    Science.gov (United States)

    Yao, Nina Y; O'Donnell, Mike

    2012-01-01

    The eukaryotic RFC clamp loader couples the energy of ATP hydrolysis to open and close the circular PCNA sliding clamp onto primed sites for use by DNA polymerases and repair factors. Structural studies reveal clamp loaders to be heteropentamers. Each subunit contains a region of homology to AAA+ proteins that defines two domains. The AAA+ domains form a right-handed spiral upon binding ATP. This spiral arrangement generates a DNA binding site within the center of RFC. DNA enters the central chamber through a gap between the AAA+ domains of two subunits. Specificity for a primed template junction is achieved by a third domain that blocks DNA, forcing it to bend sharply. Thus only DNA with a flexible joint can bind the central chamber. DNA entry also requires a slot in the PCNA clamp, which is opened upon binding the AAA+ domains of the clamp loader. ATP hydrolysis enables clamp closing and ejection of RFC, completing the clamp loading reaction.

  14. Ergonomic redesign and evaluation of a clamping tool handle.

    Science.gov (United States)

    Jung, Myung-Chul; Hallbeck, M Susan

    2005-09-01

    The handle of a commercial bar clamp was redesigned using ergonomic principles and then compared with an original clamp. Ten male and ten female students participated in simulated clamping tasks under various conditions, including different clamping heights, clamping methods, and handle-gripping methods, with respect to the dependent variables of clamping and handle-squeezing forces. The results showed that the redesigned clamp produced larger clamping force with lower handle-squeezing forces than the original clamp. As expected, males exerted more force than females in both clamping and squeezing forces. A pistol grip method was superior to an upside-down handle-gripping method. Two-handed operation was recommended for this type of clamp by simultaneously pulling the trigger and sliding the bar in order to initially tighten around objects. This study shows that the application of ergonomic guidelines increases the efficiency and usability of manual handtools.

  15. A Neutral-point Voltage Balancing Control Method for Three-level Neutral-point-clamped Inverter%一种三电平中性点钳位逆变器中点电位控制算法

    Institute of Scientific and Technical Information of China (English)

    江才; 宋文胜; 王顺亮; 韩坤; 冯晓云

    2014-01-01

    针对电力牵引三电平中性点钳位(NPC)逆变器系统,首先分析了因调制算法引起的中点电位振荡现象。然后分别比较两种传统空间矢量脉宽调制(SVPWM)算法对中点电位振荡及负载电流总谐波畸变率(THD)的影响;在此基础上,以中点电位平衡控制和最小负载电流THD含量为目的,提出了一种基于中点电位环宽控制的 SVPWM算法。最后,通过 MALTAB/Simulink 软件仿真和dSPACE半实物平台实验研究,对3种调制算法下中点电位及负载电流 THD值进行对比分析。计算机仿真与半实物实验结果表明,中点电位环宽控制方法不但能平衡直流侧中点电位,而且能有效地减小负载电流THD含量。%The neutral-point voltage oscillation due to the modulation method is analyzed first for the three-level neutral-point-clamped (NPC) traction inverter.Then,the characteristics of the neutral-point voltage oscillation and the total harmonic distortion(THD)of load current due to two traditional space vector pulse width modulation(SVPWM)methods are compared with each other,respectively.On the basis of this,a SVPWM method with adj ustment of neutral-point hysteresis-loop width is proposed to balance the neutral-point and reduce the THD value of load current.Finally,both the amplitude of neutral-point oscillation and the THD value of load current are compared and analyzed via MATLAB/Simulink simulation and dSPACE hardware-in-the-loop experiment when the three modulation methods are adopted.Simulation and experimental results show that the adopted SVPWM method with neutral-point loop width control is efficient for balancing neutral-point voltage and reducing the THD value of load current.

  16. Patch clamp studies on root cell vacuoles of a salt-tolerant and a salt-sensitive plantago species : regulation of channel activity by salt stress.

    Science.gov (United States)

    Maathuis, F J; Prins, H B

    1990-01-01

    Plantago media L. and Plantago maritima L. differ in their strategy toward salt stress, a major difference being the uptake and distribution of ions. Patch clamp techniques were applied to root cell vacuoles to study the tonoplast channel characteristics. In both species the major channel found was a 60 to 70 picosiemens channel with a low ion selectivity. The conductance of this channel for Na(+) was the same as for K(+), P(K) (+)/P(Na) (+) = 1, whereas the cation/anion selectivity (P(K) (+)/P(c1) (-)) was about 5. Gating characteristics were voltage and calcium dependent. An additional smaller channel of 25 picosiemens was present in P. maritima. In the whole vacuole configuration, the summation of the single channel currents resulted in slowly activated inward currents (t((1/2)) = 1.2 second). Inwardly directed, ATP-dependent currents could be measured against a DeltapH gradient of 1.5 units over the tonoplast. This observation strongly indicated the physiological intactness of the used vacuoles. The open probability of the tonoplast channels dramatically decreased when plants were grown on NaCl, although single channel conductance and selectivity were not altered.

  17. Electrospinning of fibrous polymer scaffolds using positive voltage or negative voltage: a comparative study.

    Science.gov (United States)

    Tong, Ho-Wang; Wang, Min

    2010-10-01

    Electrospinning of fibrous tissue engineering scaffolds has been traditionally conducted using positive voltages. In the current study, positive voltage (PV) electrospinning and negative voltage (NV) electrospinning were investigated for forming fibrous membranes of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV). In both PV-electrospinning and NV-electrospinning, the fiber diameter generally increased with increasing needle inner diameter and PHBV concentration but decreased with increasing working distance. The use of a conductivity-enhancing surfactant, benzyl triethylammonium chloride (BTEAC), significantly reduced PHBV fiber diameters from the micron scale to the sub-micron scale. Interestingly, with increasing applied voltage, the fiber diameter increased for PV-electrospinning but decreased for NV-electrospinning. The PV-electrospun fibrous membranes from solutions without BTEAC (PVEfm) and with BTEAC (PVEfm-B) and NV-electrospun membranes from solutions without BTEAC (NVEfm) and with BTEAC (NVEfm-B) were characterized in terms of their structure, wettability, thermal properties and tensile properties. Both PVEfm and NVEfm exhibited similar water contact angles (∼104°) but the contact angle of PVEfm-B or NVEfm-B was not measurable. The elongation at break of PVEfm-B or NVEfm-B was significantly higher than that of PVEfm or NVEfm. Using NV-electrospinning or a combination of NV- and PV-electrospinning may be very useful for developing suitable scaffolds for tissue engineering applications.

  18. 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 LabVIEW should make it relatively easy for others to adapt G-clamp for new experimental applications.

  19. 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.

  20. Low-carbohydrate diet versus euglycemic hyperinsulinemic clamp for the assessment of myocardial viability with 18F-fluorodeoxyglucose-PET: a pilot study.

    Science.gov (United States)

    Soares, José; Rodrigues Filho, Filadelfo; Izaki, Marisa; Giorgi, Maria Clementina P; Catapirra, Rosa M A; Abe, Rubens; Vinagre, Carmen G C M; Cerri, Giovanni G; Meneghetti, José Cláudio

    2014-02-01

    Positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) is considered the gold standard for myocardial viability. A pilot study was undertaken to compare FDG-PET using euglycemic hyperinsulinemic clamp before (18)F-fluorodeoxyglucose ((18)F-FDG) administration (PET-CLAMP) with a new proposed technique consisting of a 24-h low-carbohydrate diet before (18)F-FDG injection (PET-DIET), for the assessment of hypoperfused but viable myocardium (hibernating myocardium). Thirty patients with previous myocardial infarction were subjected to rest (99m)Tc-sestamibi-SPECT and two (18)F-FDG studies (PET-CLAMP and PET-DIET). Myocardial tracer uptake was visually scored using a 5-point scale in a 17-segment model. Hibernating myocardium was defined as normal or mildly reduced metabolism ((18)F-FDG uptake) in areas with reduced perfusion ((99m)Tc-sestamibi uptake) since (18)F-FDG uptake was higher than the degree of hypoperfusion-perfusion/metabolism mismatch indicating a larger flow defect. PET-DIET identified 79 segments and PET-CLAMP 71 as hibernating myocardium. Both methods agreed in 61 segments (agreement = 94.5 %, κ = 0.78). PET-DIET identified 230 segments and PET-CLAMP 238 as nonviable. None of the patients had hypoglycemia after DIET, while 20 % had it during CLAMP. PET-DIET compared with PET-CLAMP had a good correlation for the assessment of hibernating myocardium. To our knowledge, these data provide the first evidence of the possibility of myocardial viability assessment with this technique.

  1. A model for voltage collapse study considering load characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, L.B. [Companhia de Energia Eletrica da Bahia (COELBA), Salvador, BA (Brazil)

    1994-12-31

    This paper presents a model for analysis of voltage collapse and instability problem considering the load characteristics. The model considers fundamentally the transmission lines represented by exact from through the generalized constants A, B, C, D and the loads as function of the voltage, emphasizing the cases of constant power, constant current and constant impedance. the study treats of the system behavior on steady state and presents illustrative graphics about the problem. (author) 12 refs., 4 figs.

  2. Oxidative Stress and Total Antioxidant Status During Internal Carotid Artery Clamping with or without Shunting: An Experimental Pilot Study.

    Science.gov (United States)

    Papapetrou, Anastasios; Moris, Demetrios; Patelis, Nikolaos; Kouvelos, George N; Bakogiannis, Chris; Klonaris, Chris; Georgopoulos, Sotiris

    2015-09-22

    BACKGROUND The exact role of shunting during carotid endarterectomy remains controversial and unclear. The aim of this experimental study was to investigate to what degree carotid clamping may induce changes in the cerebral oxidative status and to focus on the relation of these changes with shunt insertion. MATERIAL AND METHODS Forty New-Zealand rabbits were randomized into 4 groups: group 1 classifying animals with carotid shunt and patent contralateral carotid artery; group 2 shunt and occlusion of the contralateral carotid artery; group 3 no-shunt and patent contralateral carotid artery; and group 4 no-shunt and occlusion of the contralateral carotid artery. Blood samples were collected from the ipsilateral internal jugular vein, immediately after carotid clamping (time 0), and then at 5, 10, 15, 30, and 60 minutes afterwards. Evaluation of oxidative stress was accomplished by measuring the lag-time, representing the initial phase of oxidation, rate of accumulation (RA), showing concentration of free oxygen radical and total antioxidant status (TAS) representing antioxidant composition of serum. RESULTS Lag-time was significantly different in time points 0, 30 and 60 minutes within each different group. TAS was significantly different in time points 0, 15 and 60 min and RA in time points 0, 5, 10 and 60 min within each different group. 60 minutes after carotid clamping, the rate of accumulation as well as lag-time and TAS were increased in all groups, independently of using or not shunting or the presence of contralateral occlusion. After comparing groups 1, 2 and 3 regarding lag-time, TAS and RA, we did not find statistical difference among the groups at any time point. On the contrary, groups 1, 2 and 3 did show significantly different values comparing to group 4 after 60 min of occlusion. CONCLUSIONS Our experimental work based on cerebral metabolism found a significantly higher oxidative stress in models with contralateral carotid occlusion. The use of shunt

  3. The non-selective voltage-activated cation channel in the human red blood cell membrane: reconciliation between two conflicting reports and further characterisation

    DEFF Research Database (Denmark)

    Kaestner, Lars; Christophersen, Palle; Bernhardt, Ingolf;

    2000-01-01

    Erythrocyte; Patch-clamp; Non-specific; cation channel; Voltage dependence; Acetylcholin receptor......Erythrocyte; Patch-clamp; Non-specific; cation channel; Voltage dependence; Acetylcholin receptor...

  4. In situ patch-clamp recordings from Merkel cells in rat whisker hair follicles, an experimental protocol for studying tactile transduction in tactile-end organs.

    Science.gov (United States)

    Ikeda, Ryo; Ling, Jennifer; Cha, Myeounghoon; Gu, Jianguo G

    2015-04-25

    Mammals use tactile end-organs to perform sensory tasks such as environmental exploration, social interaction, and tactile discrimination. However, cellular and molecular mechanisms underlying tactile transduction in tactile end-organs remain poorly understood. The patch-clamp recording technique may be the most valuable approach for detecting and studying tactile transduction in tactile end-organs, but it is technically challenging because tactile transduction elements in an end-organ are normally inaccessible by patch-clamp recording electrodes. Here we describe an in situ patch-clamp recording protocol for the study of tactile transduction in Merkel cells of rat whisker hair follicles, one of the most sensitive tactile end-organs in mammals. This technique offers an opportunity to explore the identities and properties of ion channels that are involved in tactile transduction in whisker hair follicles, and it may also lend a useful tool for researchers to study other tactile end-organs. The experimental protocol describes procedures for 1) tissue dissection and whisker hair follicle preparation, 2) device setup and steps for performing patch-clamp recordings from Merkel cells in a whisker hair follicle, 3) methods of delivering mechanical stimuli, and 4) intra-follicle microinjection for receptor knockdown in whisker hair follicles. The main procedures in this protocol, from tissue preparation to whole-cell patch-clamp recordings, can be completed in a few hours.

  5. Elective caesarean: does delay in cord clamping for 30 s ensure sufficient iron stores at 4 months of age? A historical cohort control study.

    Science.gov (United States)

    Andersson, Ola; Hellström-Westas, Lena; Domellöf, Magnus

    2016-11-02

    To compare iron stores in infants born after elective caesarean section (CS) and a 30 s delay of umbilical cord clamping with those born vaginally after early (≤10 s) or delayed (≥180 s) cord clamping. Prospective observational study with historical control. Swedish county hospital. 64 infants born after elective CS were compared with a historical control of 166 early clamped and 168 delayed clamped after vaginal birth. Blood and iron status were measured in blood samples collected at birth, 48-96 hours after birth, 4 and 12 months of age. Ferritin at 4 months of age was the primary outcome, second outcome measures were other indicators of iron status, and haemoglobin, at 4 and 12 months of age, as well as respiratory distress at 1 and 6 hours after birth. At 4 months infants born by elective CS had better iron status than those born vaginally subjected to early cord clamping, shown by higher adjusted mean difference of ferritin concentration (39 µg/L (95% CI 10 to 60)) and mean cell volume (1.8 fL (95% CI 0.6 to 3.0)); and lower levels of transferrin receptors (-0.39 mg/L (95% CI -0.69 to -0.08)). No differences were seen between infants born after elective CS and delayed clamped vaginally born infants at 4 months. No differences were found between groups at 12 months of age. Waiting to clamp the umbilical cord for 30 s after elective CS results in higher iron stores at 4 months of age compared with early cord clamping after vaginal birth, and seems to ensure iron status comparable with those achieved after 180 s delayed cord clamping after vaginal birth. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  6. Potential Danger of Pre-Pump Clamping on Negative Pressure-Associated Gaseous Microemboli Generation During Extracorporeal Life Support--An In Vitro Study.

    Science.gov (United States)

    Wang, Shigang; Chin, Brian J; Gentile, Frank; Kunselman, Allen R; Palanzo, David; Ündar, Akif

    2016-01-01

    The objectives of this study were to investigate the relationship between revolution speed of a conventional centrifugal pump and negative pressure at the inlet of the pump by clamping the tubing upstream of the pump, and to verify whether negative pressure leads to gaseous microemboli (GME) production in a simulated adult extracorporeal life support (ECLS) system. The experimental circuit, including a Maquet Rotaflow centrifugal pump and a Medos Hilite 7000 LT polymethyl-pentene membrane oxygenator, was primed with packed red blood cells (hematocrit 35%). Negative pressure was created in the circuit by clamping the tubing upstream of the pump for 10 s, and then releasing the clamp. An emboli detection and classification quantifier was used to record GME volume and count at pre-oxygenator and post-oxygenator sites, and pressure and flow rate data were collected using a custom-based data acquisition system. All trials were conducted at 36°C at revolution speeds of 2000-4000 rpm (500 rpm increment). The flow rates were 1092.5-4708.4 mL/min at the revolution speeds of 2000-4000 rpm. Higher revolution speed generated higher negative pressure at the pre-pump site when clamping the tubing upstream of the pump (-108.3 ± 0.1 to -462.0 ± 0.5 mm Hg at 2000-4000 rpm). Moreover, higher negative pressure was associated with a larger number and volume of GME at pre-oxygenator site after de-clamp (GME count 10,573 ± 271 at pre-oxygenator site at 4000 rpm). The results showed that there was a potential danger of delivering GME to the patient when clamping pre-pump tubing during ECLS using a centrifugal pump. Our results warrant further clinical studies to investigate this phenomenon.

  7. 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...

  8. High-voltage breakdown studies on Si microstrip detectors

    CERN Document Server

    Albergo, S; Azzi, P; Babucci, E; Bacchetta, N; Bader, A J; Bagliesi, G; Basti, A; Biggeri, U; Bilei, G M; Bisello, D; Boemi, D; Bosi, F; Borrello, L; Bozzi, C; Braibant, S; Breuker, Horst; Bruzzi, Mara; Buffini, A; Busoni, S; Calefato, G; Candelori, A; Caner, A; Castaldi, R; Castro, A; Catacchini, E; Checcucci, B; Ciampolini, P; Civinini, C; Creanza, D; D'Alessandro, R; Da Rold, M; Demaria, N; De Palma, M; Dell'Orso, R; Marina, R D; Dutta, S; Eklund, C; Peisert, Anna; Feld, L; Fiore, L; Focardi, E; French, M; Freudenreich, Klaus; Fürtjes, A; Giassi, A; Giorgi, M A; Giraldo, A; Glessing, B; Gu, W H; Hall, G; Hammarström, R; Hebbeker, T; Hrubec, Josef; Muhtinen, M; Kaminski, A; Karimäki, V; Saint-Koenig, M; Krammer, Manfred; Lariccia, P; Lenzi, M; Loreti, M; Lübelsmeyer, K; Lustermann, W; Mättig, P; Maggi, G; Mannelli, M; Mantovani, G C; Marchioro, A; Mariotti, C; Martignon, G; McEvoy, B; Meschini, M; Messineo, A; My, S; Paccagnella, A; Palla, Fabrizio; Pandoulas, D; Papi, A; Parrini, G; Passeri, D; Pieri, M; Piperov, S; Potenza, R; Radicci, V; Raffaelli, F; Raymond, M; Santocchia, A; Schmitt, B; Selvaggi, G; Servoli, L; Sguazzoni, G; Siedling, R; Silvestris, L; Skog, K; Starodumov, Andrei; Stavitski, I; Stefanini, G; Tempesta, P; Tonelli, G; Tricomi, A; Tuuva, T; Vannini, C; Verdini, P G; Viertel, Gert M; Zie, Z; Li Ya Hong; Watts, S; Wittmer, B

    1999-01-01

    The breakdown performance of CMS barrel module prototype detectors and test devices with single and multi-guard structures were studied before and after neutron irradiation up to 2-10/sup 14/ 1 MeV equivalent neutrons. Before irradiation avalanche breakdown occurred at the guard ring implant edges. We measured 100-300 V higher breakdown voltage values for the devices with multi-guard than for devices with single-guard ring, After irradiation and type inversion the breakdown was smoother than before irradiation and the breakdown voltage value increased to 500-600 V for most of the devices. (9 refs).

  9. Automated planar patch-clamp.

    Science.gov (United States)

    Milligan, Carol J; Möller, Clemens

    2013-01-01

    Ion channels are integral membrane proteins that regulate the flow of ions across the plasma membrane and the membranes of intracellular organelles of both excitable and non-excitable cells. Ion channels are vital to a wide variety of biological processes and are prominent components of the nervous system and cardiovascular system, as well as controlling many metabolic functions. Furthermore, ion channels are known to be involved in many disease states and as such have become popular therapeutic targets. For many years now manual patch-clamping has been regarded as one of the best approaches for assaying ion channel function, through direct measurement of ion flow across these membrane proteins. Over the last decade there have been many remarkable breakthroughs in the development of technologies enabling the study of ion channels. One of these breakthroughs is the development of automated planar patch-clamp technology. Automated platforms have demonstrated the ability to generate high-quality data with high throughput capabilities, at great efficiency and reliability. Additional features such as simultaneous intracellular and extracellular perfusion of the cell membrane, current clamp operation, fast compound application, an increasing rate of parallelization, and more recently temperature control have been introduced. Furthermore, in addition to the well-established studies of over-expressed ion channel proteins in cell lines, new generations of planar patch-clamp systems have enabled successful studies of native and primary mammalian cells. This technology is becoming increasingly popular and extensively used both within areas of drug discovery as well as academic research. Many platforms have been developed including NPC-16 Patchliner(®) and SyncroPatch(®) 96 (Nanion Technologies GmbH, Munich), CytoPatch™ (Cytocentrics AG, Rostock), PatchXpress(®) 7000A, IonWorks(®) Quattro and IonWorks Barracuda™, (Molecular Devices, LLC); Dynaflow(®) HT (Cellectricon

  10. An In Vivo Study of Low-Dose Intra-Articular Tranexamic Acid Application with Prolonged Clamping Drain Method in Total Knee Replacement: Clinical Efficacy and Safety

    Directory of Open Access Journals (Sweden)

    Paphon Sa-ngasoongsong

    2015-01-01

    Full Text Available Background. Recently, combined intra-articular tranexamic acid (IA-TXA injection with clamping drain method showed efficacy for blood loss and transfusion reduction in total knee replacement (TKR. However, until now, none of previous studies revealed the effect of this technique on pharmacokinetics, coagulation, and fibrinolysis. Materials and Methods. An experimental study was conducted, during 2011-2012, in 30 patients undergoing unilateral TKR. Patients received IA-TXA application and then were allocated into six groups regarding clamping drain duration (2-, 4-, 6-, 8-, 10-, and 12-hours. Blood and drainage fluid were collected to measure tranexamic acid (TXA level and related coagulation and fibrinolytic markers. Postoperative complication was followed for one year. Results. There was no significant difference of serum TXA level at 2 hour and 24 hour among groups (p<0.05. Serum TXA level at time of clamp release was significantly different among groups with the highest level at 2 hour (p<0.0001. There was no significant difference of TXA level in drainage fluid, postoperative blood loss, blood transfusion, and postoperative complications (p<0.05.  Conclusions. Low-dose IA-TXA application in TKR with prolonged clamping drain method is a safe and effective blood conservative technique with only minimal systemic absorption and without significant increase in systemic absorption over time.

  11. The Relationship between Adiposity and Insulin Sensitivity in African Women Living with the Polycystic Ovarian Syndrome: A Clamp Study

    Science.gov (United States)

    Dohbit, Sama; Tchana-Sinou, Mycilline; Foumane, Pascal; Donfack, Olivier Trésor; Doh, Anderson S.

    2016-01-01

    Objectives. We aimed to assess the variation of insulin sensitivity in relation to obesity in women living with PCOS in a sub-Sahara African setting. Methods. We studied body composition, insulin sensitivity, and resting energy expenditure in 14 PCOS patients (6 obese and 8 nonobese) compared to 10 matched nonobese non-PCOS subjects. Insulin sensitivity was assessed using the gold standard 80 mU/m2/min euglycemic-hyperinsulinemic clamp and resting energy expenditure was measured by indirect calorimetry. Results. Insulin sensitivity adjusted to lean mass was lowest in obese PCOS subjects and highest in healthy subjects (11.2 [10.1–12.4] versus 12.9 [12.1–13.8] versus 16.6 [13.8–17.9], p = 0.012); there was a tendency for resting energy expenditure adjusted for total body mass to decrease across the groups highest in obese PCOS subjects (1411 [1368–1613] versus 1274 [1174–1355] versus 1239 [1195–1454], p = 0.306). Conclusion. In this sub-Saharan population, insulin resistance is associated with PCOS per se but is further aggravated by obesity. Obesity did not seem to be explained by low resting energy expenditure suggesting that dietary intake may be a determinant of the obesity in this context. PMID:27672393

  12. Cord pilot trial - immediate versus deferred cord clamping for very preterm birth (before 32 weeks gestation): study protocol for a randomized controlled trial.

    Science.gov (United States)

    Pushpa-Rajah, Angela; Bradshaw, Lucy; Dorling, Jon; Gyte, Gill; Mitchell, Eleanor J; Thornton, Jim; Duley, Lelia

    2014-06-30

    Preterm birth is the most important single determinant of adverse outcome in the United Kingdom; one in every 70 babies (1.4%) is born before 32 weeks (very preterm), yet these births account for over half of infant deaths.Deferring cord clamping allows blood flow between baby and placenta to continue for a short time. This often leads to increased neonatal blood volume at birth and may allow longer for transition to the neonatal circulation. Optimal timing for clamping the cord remains uncertain, however. The Cochrane Review suggests that deferring umbilical cord clamping for preterm births may improve outcome, but larger studies reporting substantive outcomes and with long-term follow-up are needed. Studies of the physiology of placental transfusion suggest that flow in the umbilical cord at very preterm birth may continue for several minutes. This pilot trial aims to assess the feasibility of conducting a large randomised trial comparing immediate and deferred cord clamping in the UK. Women are eligible for the trial if they are expected to have a live birth before 32 weeks gestation. Exclusion criteria are known monochorionic twins or clinical evidence of twin-twin transfusion syndrome, triplet or higher order multiple pregnancy, and known major congenital malformation. The interventions will be cord clamping within 20 seconds compared with cord clamping after at least two minutes. For births with cord clamping after at least two minutes, initial neonatal care is at the bedside. For the pilot trial, outcomes include measures of recruitment, compliance with the intervention, retention of participants and data quality for the clinical outcomes.Information about the trial is available to women during their antenatal care. Women considered likely to have a very preterm birth are approached for informed consent. Randomisation is close to the time of birth. Follow-up for the women is for one year, and for the children to two years of age (corrected for gestation

  13. 恒压钳位高速关断瞬变电磁发射系统%Voltage stabilized clamping and fast turn-off transient electromagnetic transmitting system

    Institute of Scientific and Technical Information of China (English)

    赵海涛; 刘丽华; 吴凯; 张建国; 方广有

    2013-01-01

    Transient electromagnetic transmitter is an important part in transient electromagnetic detection equipment. In the aspects of high-power current steep pulse transmission, high precision synchronous control, falling-edge linearity , short turn-off time, turn-off time measurement and etc. , there are still a lot of problems to be solved urgently. This paper proposes a novel extra fast turn-off transient electromagnetic transmitting system, DSP and FPGA are used to work together and provide the system with reliable driving signals and protective measures. The system adopts a voltage stabilized clamping circuit and a damping resistance circuit, and has the characteristics of short turn-off time, high current falling-edge linearity and high transmission current; besides it can improve the speed of pulse current rising-edge. The system also adopts a novel turn-off time measurement circuit, which makes the measurement simple and accurate. A GPS synchronous controller is designed, which adopts a cooperative operation mode with a temperature compensated crystal, solves the GPS short-time failure problem and improves the reliability of the system. The transmitting system field experiment was carried out,experiment results show that the system features high transmission current, good current falling-edge linearity, accurate turn-off time measurement, and precise and reliable synchronous control. The system is easy to carry,convenient to operate,and has excellent performance.%瞬变电磁发射机是瞬变电磁探测设备中的重要组成部分,在大功率电流陡脉冲发射、高精度同步控制、下降沿线性度、短关断时间和关断时间测量等方面,有许多亟待解决的问题.提出了一种瞬变电磁发射系统,DSP和FPGA协同工作为系统提供可靠的驱动信号和保护措施;提出了恒压钳位电路,配合合适的阻尼吸收电路,具有关断时间短、电流下降沿线性度高和发射电流大的特点,并可提升脉冲

  14. 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.

  15. The interaction of the neuroprotective compounds riluzole and phenobarbital with AMPA-type glutamate receptors: a patch-clamp study.

    Science.gov (United States)

    Jin, Ling-Jing; Schlesinger, Friedrich; Song, Yun-Ping; Dengler, Reinhard; Krampfl, Klaus

    2010-01-01

    Blockade of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors is a promising pharmacological strategy in the treatment of neurodegenerative diseases. The aim of the study is to elucidate if there are direct interactions of riluzole and phenobarbital with AMPA-type receptor channels and to determinethe molecular pharmacological mechanisms. The patch-clamp technique was used combining an ultrafast solution exchange system to investigate the interaction of riluzole and phenobarbital with recombinant AMPA-type glutamate receptor channels (homomeric GluR2flipGQ or nondesensitizing GluR2L504Y). A dose-dependent decrease in the relative peak current amplitude (rAmp) and the relative area-under-the-current curve (rAUC) were found after preincubation with 0.1 mmol/l or higher concentrations of riluzole. Furthermore, in coapplication experiments with GluR2L504Y, the application of 1 or 3 mmol/l riluzole showed a decrease in the current decay time constant, and a reopening current was observed at 3 mmol/l riluzole. Phenobarbital blocks AMPA receptor channels dose-dependently in the coapplication experiments, and reopening currents after removing glutamate and blocker were observed. A slight block effect after preincubation should indicate an additional competitive block effect. Riluzole and phenobarbital modulate AMPA-type receptor channels separately, which could be both characterized as a combination of open-channel block and competitive-block mechanism. Copyright 2009 S. Karger AG, Basel.

  16. Coupling capacitor voltage transformer: A model for electromagnetic transient studies

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, D.; Neves, W.L.A. [Department of Electrical Engineering, Federal University of Campina Grande, Av. Aprigio Veloso, 882 Bodocongo, 58.109-970 Campina Grande, PB (Brazil); Vasconcelos, J.C.A. [Companhia Hidro Eletrica do Sao Francisco, Rua Delmiro Gouveia, 333 Bongi, 50.761-901 Recife, PE (Brazil)

    2007-02-15

    In this work, an accurate coupling capacitor voltage transformer (CCVT) model for electromagnetic transient studies is presented. The model takes into account linear and nonlinear elements. A support routine was developed to compute the linear 230kV CCVT parameters (resistances, inductances and capacitances) from frequency response data. The magnetic core and surge arrester nonlinear characteristics were estimated from laboratory measurements as well. The model is used in connection with the electromagnetic transients program (EMTP) to predict the CCVT performance when it is submitted to transient overvoltages, as are the cases of voltages due to the ferroresonance phenomenon and circuit breaker switching. The difference between simulated and measured results is fairly small. Simulations had shown that transient overvoltages produced inside the CCVT, when a short circuit is cleared at the CCVT secondary side, are effectively damped out by the ferroresonance suppression circuit and the protection circuit. (author)

  17. Experimental study on the influence of clamping pressure on proton exchange membrane water electrolyzer (PEMWE) cell’s characteristics

    DEFF Research Database (Denmark)

    Al Shakhshir, Saher; Cui, Xiaoti; Kær, Søren Knudsen

    Energy transition can be led by more hydrogen production. Hydrogen offers a clean, sustainable, and flexible option for overcoming different obstacles that face the low-carbon economy [1]. PEMWE is one of the most promising candidate technologies to produce hydrogen from renewable energy sources...... temperature (70°C) and atmospheric pressure. Early results for IV curve predict that the PEMWE cell performance increases with increasing the clamping pressure at fixed temperature and current density. This can be elucidated by the EIS measurements which predict an increment in ohmic and activation resistance...... at lower clamping pressure values at the same temperature and current density. Furthermore, early results have not shown any significant change in the amount of hydrogen crossing-over from cathode to anode and water from anode to cathode. This might be attributed to the membrane properties which might...

  18. A study on threshold voltage stability of low operating voltage organic thin-film transistors

    Science.gov (United States)

    Padma, N.; Sen, Shaswati; Sawant, Shilpa N.; Tokas, R.

    2013-08-01

    A low operating voltage (<2 V) organic field-effect transistor (OFET) using phenylhexyltrichlorosilane (PTS) self-assembled monolayer (SAM) dielectric and copper phthalocyanine (CuPc) as semiconductor with improved mobility (0.035 cm2 V-1 s-1) and threshold voltage stability was demonstrated. This device showed better performance when compared to an OFET with octyltrichlorosilane (OTS-8) SAM dielectric. The improved mobility was attributed to the 2D growth mode of CuPc on PTS SAM because of surface energy matching between the two, whereas CuPc film on OTS-8 showed a 3D growth mode with larger grain boundary density. The higher threshold voltage stability of OFETs on PTS SAM was attributed to the efficient coverage and screening of trap centres at dielectric/semiconductor interface due to stronger intermolecular linking and formation of closely packed surface by the bulky phenyl end groups. Decrease in grain boundaries offered by 2D growth of CuPc for electron and hole trapping was also found to be another reason for improved threshold voltage stability. The results indicated that the nature of the end group of SAM dielectric, surface chemistry of dielectric and initial growth mode of semiconductors are all responsible for improvement in threshold voltage stability and enhanced performance of OFET.

  19. 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.

  20. The GLP-1 Analogue Exenatide Improves Hepatic and Muscle Insulin Sensitivity in Diabetic Rats: Tracer Studies in the Basal State and during Hyperinsulinemic-Euglycemic Clamp

    Directory of Open Access Journals (Sweden)

    Hui Wu

    2014-01-01

    Full Text Available Objective. Glucagon-like peptide-1 (GLP-1 analogues (e.g., exenatide increase insulin secretion in diabetes but less is known about their effects on glucose production or insulin-stimulated glucose uptake in peripheral tissues. Methods. Four groups of Sprague-Dawley rats were studied: nondiabetic (control, C; nondiabetic + exenatide (C + E; diabetic (D; diabetic + exenatide (D + E with diabetes induced by streptozotocin and high fat diet. Infusion of 3-3H-glucose and U-13C-glycerol was used to measure basal rates of appearance (Ra of glucose and glycerol and gluconeogenesis from glycerol (GNG. During hyperinsulinemic-euglycemic clamp, glucose uptake into gastrocnemius muscles was measured with 2-deoxy-D-14C-glucose. Results. In the diabetic rats, exenatide reduced the basal Ra of glucose (P<0.01 and glycerol (P<0.01 and GNG (P<0.001. During the clamp, Ra of glucose was also reduced, whereas the rate of disappearance of glucose increased and there was increased glucose uptake into muscle (P<0.01 during the clamp. In the nondiabetic rats, exenatide had no effect. Conclusion. In addition to its known effects on insulin secretion, administration of the GLP-1 analogue, exenatide, is associated with increased inhibition of gluconeogenesis and improved glucose uptake into muscle in diabetic rats, implying improved hepatic and peripheral insulin sensitivity.

  1. 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...... multiple unit traction system is proposed in this study. The strategy is based on a multiple frequency tuned quasi-proportional resonant controller in the ac-side current loop and a multiple frequency tuned notch filter in the dc-link voltage loop. Under the typical supply voltage distortion present...

  2. Amitriptyline and carbamazepine utilize voltage-gated ion channel suppression to impair excitability of sensory dorsal horn neurons in thin tissue slice: An in vitro study.

    Science.gov (United States)

    Wolff, Matthias; Czorlich, Patrick; Nagaraj, Chandran; Schnöbel-Ehehalt, Rose; Li, Yingji; Kwapiszewska, Grazyna; Olschewski, Horst; Heschl, Stefan; Olschewski, Andrea

    2016-08-01

    Amitriptyline, carbamazepine and gabapentin are often used for the treatment of neuropathic pain. However, their analgesic action on central sensory neurons is still not fully understood. Moreover, the expression pattern of their target ion channels is poorly elucidated in the dorsal horn of the spinal cord. Thus, we performed patch-clamp investigations in visualized neurons of lamina I-III of the spinal cord. The expression of the different voltage-gated ion channels, as the targets of these drugs, was detected by RT-PCR and immunohistochemistry. Neurons of the lamina I-III express the TTX-sensitive voltage-gated Na(+) as well as voltage-gated K(+) subunits assembling the fast inactivating (A-type) currents and the delayed rectifier K(+) currents. Our pharmacological studies show that tonically-firing, adapting-firing and single spike neurons responded dose-dependently to amitriptyline and carbamazepine. The ion channel inhibition consecutively reduced the firing rate of tonically-firing and adapting-firing neurons. This study provides evidence for the distribution of voltage-gated Na(+) and K(+) subunits in lamina I-III of the spinal cord and for the action of drugs used for the treatment of neuropathic pain. Our work confirms that modulation of voltage-gated ion channels in the central nervous system contributes to the antinociceptive effects of these drugs.

  3. 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...... 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....

  4. Reconstruction of Cell Surface Densities of Ion Pumps, Exchangers, and Channels from mRNA Expression, Conductance Kinetics, Whole-Cell Calcium, and Current-Clamp Voltage Recordings, with an Application to Human Uterine Smooth Muscle Cells.

    Directory of Open Access Journals (Sweden)

    Jolene Atia

    2016-04-01

    Full Text Available Uterine smooth muscle cells remain quiescent throughout most of gestation, only generating spontaneous action potentials immediately prior to, and during, labor. This study presents a method that combines transcriptomics with biophysical recordings to characterise the conductance repertoire of these cells, the 'conductance repertoire' being the total complement of ion channels and transporters expressed by an electrically active cell. Transcriptomic analysis provides a set of potential electrogenic entities, of which the conductance repertoire is a subset. Each entity within the conductance repertoire was modeled independently and its gating parameter values were fixed using the available biophysical data. The only remaining free parameters were the surface densities for each entity. We characterise the space of combinations of surface densities (density vectors consistent with experimentally observed membrane potential and calcium waveforms. This yields insights on the functional redundancy of the system as well as its behavioral versatility. Our approach couples high-throughput transcriptomic data with physiological behaviors in health and disease, and provides a formal method to link genotype to phenotype in excitable systems. We accurately predict current densities and chart functional redundancy. For example, we find that to evoke the observed voltage waveform, the BK channel is functionally redundant whereas hERG is essential. Furthermore, our analysis suggests that activation of calcium-activated chloride conductances by intracellular calcium release is the key factor underlying spontaneous depolarisations.

  5. Reconstruction of Cell Surface Densities of Ion Pumps, Exchangers, and Channels from mRNA Expression, Conductance Kinetics, Whole-Cell Calcium, and Current-Clamp Voltage Recordings, with an Application to Human Uterine Smooth Muscle Cells.

    Science.gov (United States)

    Atia, Jolene; McCloskey, Conor; Shmygol, Anatoly S; Rand, David A; van den Berg, Hugo A; Blanks, Andrew M

    2016-04-01

    Uterine smooth muscle cells remain quiescent throughout most of gestation, only generating spontaneous action potentials immediately prior to, and during, labor. This study presents a method that combines transcriptomics with biophysical recordings to characterise the conductance repertoire of these cells, the 'conductance repertoire' being the total complement of ion channels and transporters expressed by an electrically active cell. Transcriptomic analysis provides a set of potential electrogenic entities, of which the conductance repertoire is a subset. Each entity within the conductance repertoire was modeled independently and its gating parameter values were fixed using the available biophysical data. The only remaining free parameters were the surface densities for each entity. We characterise the space of combinations of surface densities (density vectors) consistent with experimentally observed membrane potential and calcium waveforms. This yields insights on the functional redundancy of the system as well as its behavioral versatility. Our approach couples high-throughput transcriptomic data with physiological behaviors in health and disease, and provides a formal method to link genotype to phenotype in excitable systems. We accurately predict current densities and chart functional redundancy. For example, we find that to evoke the observed voltage waveform, the BK channel is functionally redundant whereas hERG is essential. Furthermore, our analysis suggests that activation of calcium-activated chloride conductances by intracellular calcium release is the key factor underlying spontaneous depolarisations.

  6. Study of High Voltage AC Underground Cable Systems

    DEFF Research Database (Denmark)

    da Silva, Filipe Miguel Faria; Bak, Claus Leth; Wiechowski, Wojciech T.

    2010-01-01

    High-Voltage cables are starting to be more often used to transmit electric energy at high-voltage levels, introducing in the electric grid phenomena that are uncommon when using Overhead Lines. Under the phenomena worthy of special attention are those related with the cable energisation and deen...

  7. 一种有源箝位交错并联 Boost电路的研究%Study on an Active-Clamped Interleaved Boost Circuit

    Institute of Scientific and Technical Information of China (English)

    胡培民; 翁晓光; 王勤

    2016-01-01

    为提高Boost变换器传输效率,提出了一种运用辅助电感和箝位电路实现交错并联Boost电路软开关的拓扑结构,变换器不仅实现了主开关管的零电流开通和零电压关断,大大减少了二极管的反向恢复电流带来的能量损耗。同时实现了辅助开关管的零电压开关,降低了附加损耗。在原理仿真的基础上,设计试制了一台实验样机。实验结果给出了开关管波形,验证了软开关功能的实现。%To improve the transmission efficiency of the Boost converter,this paper presents a topological structure using an auxiliary inductor and clamping circuit to realize soft switching of the interleaved Boost circuit.The converter does not only achieve zero current turning-on and zero voltage turning-off of the main switch tube,thus greatly reducing the energy loss caused by the reverse-recovery current of the diode,it also realizes zero voltage switching of the auxiliary switching tube and reduces additional loss.On the basis of the principle of emulating,an experimental prototype is designed and made.Experimental results give the waveform of the switching tube and verify realization of the function of soft switching.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  9. Single electrode dynamic clamp with StdpC.

    Science.gov (United States)

    Samu, David; Marra, Vincenzo; Kemenes, Ildiko; Crossley, Michael; Kemenes, György; Staras, Kevin; Nowotny, Thomas

    2012-10-15

    Dynamic clamp is a powerful approach for electrophysiological investigations allowing researchers to introduce artificial electrical components into target neurons to simulate ionic conductances, chemical or electrotonic inputs or connections to other cells. Due to the rapidly changing and potentially large current injections during dynamic clamp, problematic voltage artifacts appear on the electrode used to inject dynamic clamp currents into a target neuron. Dynamic clamp experiments, therefore, typically use two separate electrodes in the same cell, one for recording membrane potential and one for injecting currents. The requirement for two independent electrodes has been a limiting factor for the use of dynamic clamp in applications where dual recordings of this kind are difficult or impossible to achieve. The recent development of an active electrode compensation (AEC) method has overcome some of these prior limitations, permitting artifact-free dynamic clamp experimentation with a single electrode. Here we describe an AEC method for the free dynamic clamp software StdpC. The AEC component of StdpC is the first such system implemented for the use of non-expert users and comes with a set of semi-automated configuration and calibration procedures that facilitate its use. We briefly introduce the AEC method and its implementation in StdpC and then validate it with an electronic model cell and in two different biological preparations.

  10. A genetic study of the human low-voltage electroencephalogram.

    Science.gov (United States)

    Anokhin, A; Steinlein, O; Fischer, C; Mao, Y; Vogt, P; Schalt, E; Vogel, F

    1992-01-01

    The studied phenotype, the low-voltage electroencephalogram (LVEEG), is characterized by the absence of an alpha rhythm from the resting EEG. In previous studies, evidence was found for a simple autosomal-dominant mode of inheritance of the LVEEG. Such a polymorphism in brain function can be used as a research model for the stepwise elucidation of the molecular mechanism involved in those aspects of neuronal activity that are reflected in the EEG. Linkage with the variable number of tandem repeats (VNTR) marker CMM6 (D20S19) and localization of an LVEEG (EEGV1) gene on 20q have previously been reported, and genetic heterogeneity has been demonstrated. This latter result has been corroborated by studying new marker (MS214). The phenotype of the LVEEG is described here in greater detail. Its main characteristic is the absence of rhythmic alpha activity, especially in occipital leads, whereas other wave forms such as beta or theta waves may be present. Analysis of 17 new families (some of them large), together with 60 previously described nuclear families, supports the genetic hypothesis of an autosomal-dominant mode of inheritance. Problems connected with the analysis of linkage heterogeneity, exclusion mapping, and the study of multipoint linkage are discussed. A possible explanation of the localization of LVEEG in the close vicinity of another gene influencing synchronization of the normal EEG, the gene for benign neonatal epilepsie, is given.

  11. Indirect Field Oriented Control for Five Phase Three Level Neutral Point Clamped Inverter Fed PMSM Drive

    Directory of Open Access Journals (Sweden)

    S. Sengottaian

    2015-08-01

    Full Text Available This study deals with a five phase three level Neutral Point Clamped (NPC inverter fed PMSM drive application. The motor performances depend upon mathematical model so the parameters vary are: noise, common mode voltage, flux variation and harmonic levels of the inverter or motor. Voltage saturation is one of the major problems of a motor which occurs due to speed oscillations, more current fluctuations. This problem can be solved by using PWM technique depends on the reference motor torque and flux. In this study Indirect Field Oriented Control (IFOC NPC inverter is suggested to reduce the voltage saturation. The three level neutral point clamped inverter is widely used for medium and high level applications. Compared with standard two level inverter, this type of NPC inverters have more merits. It generates greater number of levels output waveform in lower harmonic content at the same switching frequency and less voltage stress across the semiconductor switches; finally motor performance and control schemes are verified by using MATLAB/SIMULINK.

  12. Study of the breakdown voltage of SiPMs

    CERN Document Server

    Chmill, V; Klanner, R; Nitschke, M; Schwandt, J

    2016-01-01

    The breakdown behaviour of SiPMs (Silicon PhotoMultiplier) with pixel sizes of 15$\\times $15, 25$\\times $25, 50$\\times $50, and 100$\\times $100 $\\mu $m$^2$, manufactured by KETEK, has been investigated. From the current-voltage characteristics measured with and without illumination by LED light of 470 nm wavelength, the current-breakdown voltage, $V_I$, and from linear fits of the voltage dependence of the SiPM gain, measured by recording pulse-area spectra, the gain-breakdown voltage, $V_G$, have been obtained. The voltage dependence of the Geiger-breakdown probability was determined from the fraction of zero photoelectron events with LED illumination. By comparing the results to a model calculation, the photodetection-breakdown voltage, $V_{PD}$, has been determined. Within experimental uncertainties, $V_I$ and $V_{PD}$ are equal and independent of pixel size. For $V_G$, a dependence on pixel size is observed. The difference $V_I - V_G$ is about 1 V for the SiPM with 15 $\\mu $m pixels, decreases with pixel ...

  13. Study of the breakdown voltage of SiPMs

    Science.gov (United States)

    Chmill, V.; Garutti, E.; Klanner, R.; Nitschke, M.; Schwandt, J.

    2017-02-01

    The breakdown behaviour of SiPMs (Silicon PhotoMultiplier) with pixel sizes of 15 × 15 , 25 × 25 , 50 × 50, and 100 × 100 μm2, manufactured by KETEK, has been investigated. From the current-voltage characteristics measured with and without illumination by LED light of 470 nm wavelength, the current-breakdown voltage, VI, and from linear fits of the voltage dependence of the SiPM gain, measured by recording pulse-area spectra, the gain-breakdown voltage, VG, have been obtained. The voltage dependence of the Geiger-breakdown probability was determined from the fraction of zero photoelectron events with LED illumination. By comparing the results to a model calculation, the photodetection-breakdown voltage, VPD, has been determined. Within experimental uncertainties, VI and VPD are equal and independent of pixel size. For VG, a dependence on pixel size is observed. The difference VI -VG is about 1 V for the SiPM with 15 μm pixels, decreases with pixel size and is compatible with zero for the SiPM with 100 μm pixels.

  14. Design and analysis of different trigger techniques for ESD clamp circuit in 0.5-µm 5 V/18 V CDMOS process

    Science.gov (United States)

    Zhang, Wenjie; Yang, Liu; Wang, Yang; Jin, Xiangliang

    2017-09-01

    In this work, gate-driven, substrate-triggered and gate-substrate-triggered techniques for both 5 V NMOS-based and 18 V NLDMOS-based power clamps under electrostatic discharge (ESD) stress were investigated in details. Schematics of the three trigger designs were depicted and their physical mechanisms were studied at first. To verify and make comparisons of their performance, they were fabricated in a standard 0.5-μm 5 V/18 V CDMOS process and characterized by transmission line pulse (TLP) test system, respectively. Experimental results show that 5 V NMOS-based power clamp with substrate-triggered technique has the lowest trigger voltage (∼8.37 V) and the highest failure current (∼3.58 A), and 18 V gate-substrate-triggered design based on NLDMOS has low trigger voltage (∼34.02 V) and greatest robustness (It2 = 3.32 A). Therefore, as for low-voltage NMOS-based ESD power clamps, substrate-triggered design obtains the most superior ESD protection performance; but for high-voltage power clamps, gate-substrate-triggered technique can make NLDMOS actualize uniform current conduction and better ESD robustness.

  15. A comparative study of the action of tolperisone on seven different voltage dependent sodium channel isoforms.

    Science.gov (United States)

    Hofer, Doris; Lohberger, Birgit; Steinecker, Bibiane; Schmidt, Kurt; Quasthoff, Stefan; Schreibmayer, Wolfgang

    2006-05-24

    The specific, acute interaction of tolperisone, an agent used as a muscle relaxant and for the treatment of chronic pain conditions, with the Na(v1.2), Na(v1.3), Na(v1.4), Na(v1.5), Na(v1.6), Na(v1.7), and Na(v1.8) isoforms of voltage dependent sodium channels was investigated and compared to that of lidocaine. Voltage dependent sodium channels were expressed in the Xenopus laevis oocyte expression system and sodium currents were recorded with the two electrode voltage clamp technique. Cumulative dose response relations revealed marked differences in IC(50) values between the two drugs on identical isoforms, as well as between isoforms. A detailed kinetic analysis uncovered that tolperisone as well as lidocaine exhibited their blocking action not only via state dependent association/dissociation with voltage dependent sodium channels, but a considerable fraction of inhibition is tonic, i.e. permanent and basic in nature. Voltage dependent activation was affected to a minor extent only. A shift in steady-state inactivation to more negative potentials could be observed for most drug/isoform combinations. The contribution of this shift to overall block was, however, small at drug concentrations resulting in considerable overall block. Recovery from inactivation was affected notably by both drugs. Lidocaine application led to a pronounced prolongation of the time constant of the fast recovery process for the Na(v1.3), Na(v1.5), and Na(v1.7) isoforms, indicating common structural properties in the local anesthetic receptor site of these three proteins. Interestingly, this characteristic drug action was not observed for tolperisone.

  16. Safety and efficacy of delayed umbilical cord clamping in multiple and singleton premature infants - A quality improvement study.

    Science.gov (United States)

    Ruangkit, C; Moroney, V; Viswanathan, S; Bhola, M

    2015-01-01

    To evaluate the safety and efficacy of a quality improvement (QI) program of delayed umbilical cord clamping (DCC) in multiple and singleton preterm infants born at our center. After DCC protocol implementation, compliance and success rate were assessed. Clinical outcomes of selected 150 preterm infants <34 weeks gestation born in 2014 after protocol implementation (Epoch II) were compared to those of preterm infants born in 2013 before protocol implementation (Epoch I). Overall protocol compliance rate was 92% (246/267). DCC was successfully performed in 77% (205/267) after protocol implementation. There were higher multiple births in Epoch II compared to Epoch I (27.3 vs. 15.3% , p <  0.01). At birth, infants in Epoch II had significantly decreased need for intubation in delivery room (23.3 vs. 39.3% , p <  0.01), had higher hematocrit (46.4±7.3 vs. 44.0±7.1% , p <  0.01) and less metabolic acidosis (base excess -4.1±2.7 vs. -5.3±4.2 mmol/L, p <  0.01) compared to those born in Epoch I. During hospital stay, fewer infants in Epoch II received rescue surfactant therapy (45.3 vs. 56.7% , p = 0.05), medical treatment for PDA (6.7 vs. 16.6% , p = 0.04%) and red blood cell transfusions (20.7 VS. 32.0% , p <  0.01) compared to Epoch I. Protocol-guided practice of DCC for 30 seconds can be safely performed in multiple and singleton preterm infants. In addition to higher initial hematocrit, infants in our QI project had lower need for delivery room resuscitation and less metabolic acidosis at birth. We also observed decreased need for rescue surfactant therapy, medical treatment for PDA and red blood cell transfusions after DCC protocol implementation.

  17. Consistency and diversity of spike dynamics in the neurons of bed nucleus of stria terminalis of the rat: a dynamic clamp study.

    Directory of Open Access Journals (Sweden)

    Attila Szücs

    Full Text Available Neurons display a high degree of variability and diversity in the expression and regulation of their voltage-dependent ionic channels. Under low level of synaptic background a number of physiologically distinct cell types can be identified in most brain areas that display different responses to standard forms of intracellular current stimulation. Nevertheless, it is not well understood how biophysically different neurons process synaptic inputs in natural conditions, i.e., when experiencing intense synaptic bombardment in vivo. While distinct cell types might process synaptic inputs into different patterns of action potentials representing specific "motifs" of network activity, standard methods of electrophysiology are not well suited to resolve such questions. In the current paper we performed dynamic clamp experiments with simulated synaptic inputs that were presented to three types of neurons in the juxtacapsular bed nucleus of stria terminalis (jcBNST of the rat. Our analysis on the temporal structure of firing showed that the three types of jcBNST neurons did not produce qualitatively different spike responses under identical patterns of input. However, we observed consistent, cell type dependent variations in the fine structure of firing, at the level of single spikes. At the millisecond resolution structure of firing we found high degree of diversity across the entire spectrum of neurons irrespective of their type. Additionally, we identified a new cell type with intrinsic oscillatory properties that produced a rhythmic and regular firing under synaptic stimulation that distinguishes it from the previously described jcBNST cell types. Our findings suggest a sophisticated, cell type dependent regulation of spike dynamics of neurons when experiencing a complex synaptic background. The high degree of their dynamical diversity has implications to their cooperative dynamics and synchronization.

  18. Elevation of serum insulin concentration during euglycemic hyperinsulinemic clamp studies leads to similar activation of insulin receptor kinase in skeletal muscle of subjects with and without NIDDM

    DEFF Research Database (Denmark)

    Klein, H H; Vestergaard, H; Kotzke, G;

    1995-01-01

    The role of skeletal muscle insulin receptor kinase in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM) was investigated. Muscle biopsies from 13 patients with NIDDM and 10 control subjects at fasting serum insulin concentrations and approximately 1,000 pmol/l steady-state serum...... insulin during euglycemic hyperinsulinemic clamps were immediately frozen. The biopsies were then solubilized, and the receptors were immobilized to anti-insulin receptor antibody-coated microwells. Receptor kinase and binding activities were consecutively measured in these wells. The increase in serum...... insulin concentration (73 +/- 14 to 1,004 +/- 83 and 45 +/- 7 to 1,07 +/- 77 pmol/l in the NIDDM and control groups, respectively) had similar effects on receptor kinase activity in both study groups (12 +/- 1 to 42 +/- 5 and 12 +/- 2 to 47 +/- 5 amol P.fmol binding activity-1. min-1 in the NIDDM...

  19. Inventing a co-axial atomic resolution patch clamp to study a single resonating protein complex and ultra-low power communication deep inside a living neuron cell.

    Science.gov (United States)

    Ghosh, Subrata; Sahu, Satyajit; Agrawal, Lokesh; Shiga, Takashi; Bandyopadhyay, Anirban

    2016-12-01

    To read the signals of single molecules in vitro on a surface, or inside a living cell or organ, we introduce a coaxial atom tip (coat) and a coaxial atomic patch clamp (COAPAP). The metal-insulator-metal cavity of these probes extends to the atomic scale (0.1[Formula: see text]nm), it eliminates the cellular or environmental noise with a S/N ratio 10(5). Five ac signals are simultaneously applied during a measurement by COAT and COAPAP to shield a true signal under environmental noise in five unique ways. The electromagnetic drive in the triaxial atomic tips is specifically designed to sense anharmonic vibrational and transmission signals for any system between 0.1[Formula: see text]nm and 50[Formula: see text]nm where the smallest nanopatch clamp cannot reach. COAT and COAPAP reliably pick up the atomic scale vibrations under the extreme noise of a living cell. Each protein's distinct electromagnetic, mechanical, electrical and ionic vibrational signature studied in vitro in a protected environment is found to match with the ones studied inside a live neuron. Thus, we could confirm that by using our probe blindly we could hold on to a single molecule or its complex in the invisible domain of a living cell. Our decade long investigations on perfecting the tools to measure bio-resonance of all forms and simultaneously in all frequency domains are summarized. It shows that the ratio of emission to absorption resonance frequencies of a biomaterial is around [Formula: see text], only a few in the entire em spectrum are active that regulates all other resonances, like mechanical, ionic, etc.

  20. An Experimental Study on Voltage Compensation Method using Autonomous Decentralized Control of Distributed Generators

    Science.gov (United States)

    Tanaka, Shunsuke; Suzuki, Hirokazu

    When many distributed generators (DGs) are connected to a distribution line, the upward power flow from DGs causes the difficulty in line voltage regulation. As the countermeasure, we propose several methods to control the line voltage by use of DGs' reactive power outputs. These methods using only DGs' reactive power are implemented in an autonomous decentralized way. DGs with the function to estimate the line impedance provide the power system with reactive power according to the estimated impedance value, and regulate the line voltage. We evaluate the effect of the proposed methods for voltage compensation by experimental studies using commercial grid-connected inverters for PV system.

  1. Management of umbilical cord clamping.

    Science.gov (United States)

    Webbon, Lucy

    2013-02-01

    The Royal College of Midwives (RCM) has updated its third stage of labour guidelines (RCM 2012) to be clearly supportive of a delay in umbilical cord clamping, although specific guidance on timing is yet to be announced. It is therefore imperative that both midwives and student midwives understand and are able to integrate delaying into their practice, as well as communicating to women the benefits; only in this way can we give women fully informed choices on this aspect of care. The main benefit of delayed cord clamping is the protection it can provide in reducing childhood anaemia, which is a major issue, especially in poorer countries. A review of the evidence found no risks linked to delayed clamping, and no evidence that it cannot be used in combination with the administration of uterotonic drugs. Delayed cord clamping can be especially beneficial for pre term and compromised babies.

  2. 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.

  3. Applications of alcohol clamping in early drug development

    NARCIS (Netherlands)

    Zoethout, Remco Wiebe Martijn

    2012-01-01

    This thesis describes the development of a novel alcohol clamp, a new method to obtain stable plasma levels of alcohol and its application in CNS-research. The method might have several advantages that were explored in subsequent studies described in this thesis. The stability of the alcohol clamp w

  4. A Comparative Study of Ultra-Low Voltage Digital Circuit Design

    Directory of Open Access Journals (Sweden)

    Aaron Arthurs

    2012-07-01

    Full Text Available Ultra-low voltage digital circuit design is an active research area, especially for portable applications such as wearable electronics, intelligent remote sensors, implantable medical devices, and energy-harvesting systems. Due to their application scenarios and circuit components, two major goals for these systems are minimizing energy consumption and improving compatibility with low-voltage power supplies and analog components. The most effective solution to achieve these goals is to reduce the supply voltage, which,however, raises the issue of operability. At ultra-low supply voltages, the integrity of digital signals degrades dramatically due to the indifference between active and leakage currents. In addition, the system timing becomes more unpredictable as the impact of process and supply voltage variations being more significant at lower voltages. This paper presents a comparative study among three techniques for designing digital circuits operating at ultra-low voltages, i.e., Schmitt-triggered gate structure, delayinsensitive asynchronous logic, and Fully-Depleted Silicon-on-Insulator technology. Results show that despite the tradeoffs, all eight combinations of these techniques are viable for designing ultra-low voltage circuits. For a given application, the optimum circuit design can be selected from these combinations based on the lowest voltage, the dynamic range, the power budget, the performance requirement, and the available semiconductor process node.

  5. A Comparative Study of Ultra-Low Voltage Digital Circuit Design

    Directory of Open Access Journals (Sweden)

    Aaron Arthurs,

    2012-06-01

    Full Text Available Ultra-low voltage digital circuit design is an active research area, especially for portable applications such as wearable electronics, intelligent remote sensors, implantable medical devices, and energy-harvesting systems. Due to their application scenarios and circuit components, two major goals for these systems are minimizing energy consumption and improving compatibility with low-voltage power supplies and analog components. The most effective solution to achieve these goals is to reduce the supply voltage, which,however, raises the issue of operability. At ultra-low supply voltages, the integrity of digital signals degrades dramatically due to the indifference between active and leakage currents. In addition, the system timing becomes more unpredictable as the impact of process and supply voltage variations being more significant at lower voltages. This paper presents a comparative study among three techniques for designing digital circuits operating at ultra-low voltages, i.e., Schmitt-triggered gate structure, delay insensitive asynchronous logic, and Fully-Depleted Silicon-on-Insulator technology. Results show that despite the trade offs, all eight combinations of these techniques are viable for designing ultra-low voltage circuits. For a given application, the optimum circuit design can be selected from these combinations based on the lowest voltage, the dynamic range, the power budget, the performance requirement, and the available semiconductor process node.

  6. Impact Study of Electric Vehicle (EV) Integration on Medium Voltage (MV) Grids

    DEFF Research Database (Denmark)

    Wu, Qiuwei; Nielsen, Arne Hejde; Østergaard, Jacob

    2011-01-01

    The impact study of electric vehicle (EV) grid integration on medium voltage (MV) grids was carried out to quantify the power component loading and voltage profile change in MV grids due to the extra demands from the EV charging. Three charging scenarios, dumb charging, time charging and fleet...

  7. Location, Tilt, and Binding : A Molecular Dynamics Study of Voltage-Sensitive Dyes in Biomembranes

    NARCIS (Netherlands)

    Hinner, Marlon J.; Marrink, Siewert-J.; de Vries, Alex H.

    2009-01-01

    We present a molecular dynamics study on the interaction of styryl-type voltage-sensitive dyes with a lipid membrane. In this work, voltage-sensitive dyes are proposed as interesting model amphiphiles for biomolecular simulation, due to the wealth of biophysical and thermodynamical data available on

  8. Cerebral haemodynamics during carotid cross-clamping.

    Science.gov (United States)

    Pistolese, G R; Ippoliti, A; Appolloni, A; Ronchey, S; Faraglia, V

    1993-03-01

    Carotid artery cross-clamping ischaemia during carotid endarterectomy (CEA) causes 5-30% of perioperative neurological deficits. This study was performed to identify possible clinical situations at higher risk for carotid cross-clamping ischaemia. 606 consecutive patients underwent CEA and were retrospectively studied; they were grouped according to risk factors, presence of associated vascular diseases, clinical pattern, angiographic and CT scan findings. Stump pressure measurement was provided in all patients, perioperative monitoring during CEA was performed by electroencephalogram (EEG) in 469 (77%) and somatosensorial evoked potentials (SEP) in 137 (23%). Local anaesthesia was used in 88 (14.5%) patients. Ischaemic changes during carotid cross-clamping were registered in 118 patients (19.5%). The incidence of cross-clamping ischaemia was then related to different factors; it affected 5.6% of asymptomatics, 25.4% of patients with fixed stroke and 38.5% of those with stenosis and contralateral occlusion. Angiographic and clinical correlation showed that patients with more severe lesions are mostly affected by clamping ischaemia (up to 55% in those with stroke and stenosis with contralateral occlusion). Age, hypertension and diabetes do not significantly affect incidence of ischaemic changes. Positive CT scan increased this risk; statistical relevance was found in regard to patients with unilateral or bilateral stenosis and in those with transient ischaemic attacks. A higher risk can be expected for subjects with more severe clinical and instrumental findings, even if no patients can be considered completely at risk or risk free. Perioperative monitoring is always mandatory and is of great importance in detecting ischaemic changes and preventing cerebral damage using a temporary intraluminal shunt.

  9. High voltage, low inductance hydrogen thyratron study program

    Science.gov (United States)

    Caristi, R. F.; Turnquist, D.

    1981-01-01

    The second phase of a multi-phase program of research and development to gain the information necessary to fabricate a high voltage, low inductance hydrogen thyratron switch has now been completed. The thyratron is to be capable of switching tens of kiloamperes within tens of nanoseconds at voltage levels as high as 250 kV. To achieve low inductance, the thyratron is operated within a close-fitting coaxial current return. Both the tube and the return are made physically short, and the tube is designed such that the discharge is constrained to flow principally at the outer reaches of the device. A technique has been developed for modelling various types of box grids and then using computer-generated field plots to aid in the specifics of grid design. This model has been used to generate a comprehensive set of theoretical relations that are useful to determine the anode dissipation to be expected. Experimental results are described and discussed. Included are the ceramic test results, holdoff vs. time on charge and gas pressure, stage voltage addition, operation at high pulse repetition rates, current rise time as a function of gas pressure, and the triggering characteristics of multi-stage, box-grid tubes. Finally, the design of an intermediate experimental tube is discussed at length. This tube is expected to have an inductance less than 50 nH and to operate at 150 kV. Its design is based on both the theoretical and experimental results obtained during this phase of the research program. The overall conclusion is that a hydrogen thyratron capable of achieving the program's objectives is a feasible proposition.

  10. Voltage Support Study of Smart PV Inverters on a High-Photovoltaic Penetration Utility Distribution Feeder

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Fei; Pratt, Annabelle; Bialek, Tom; Bell, Frances; McCarty, Michael; Atef, Kahveh; Nagarajan, Adarsh; Gotseff, Peter

    2016-11-21

    This paper reports on tools and methodologies developed to study the impact of adding rooftop photovoltaic (PV) systems, with and without the ability to provide voltage support, on the voltage profile of distribution feeders. Simulation results are provided from a study of a specific utility feeder. The simulation model of the utility distribution feeder was built in OpenDSS and verified by comparing the simulated voltages to field measurements. First, we set all PV systems to operate at unity power factor and analyzed the impact on feeder voltages. Then we conducted multiple simulations with voltage support activated for all the smart PV inverters. These included different constant power factor settings and volt/VAR controls.

  11. Study of Voltage-Controlled Characteristics for Thermoelectric Coolers

    Science.gov (United States)

    Wang, Ning; Chen, Ming-Ming; Jia, Hong-Zhi; Jin, Tao; Xie, Ji-Long

    2017-01-01

    Based on the Peltier effect, thermoelectric coolers (TECs) have been widely used in solving thermal management issues for semiconductor devices such as semiconductor laser, charge-coupled devices and nanoelectronic circuits with hot-spots. However, performance control mechanisms especially voltage-controlled parameters for TEC still face challenges. In this paper, a standard mathematical model for multi-stage TECs is proposed with thermal resistances from both sides and performance parameters dependent on voltage. The proposed models agreed with experimental results. Compared with the available model, the relative standard deviations between the obtained equivalent thermal conductivity model and experimental results at 25°C and 50°C are decreased by 88.87% and 30.14%, respectively. Also, the relative standard deviations between the proposed thermoelectric figure of merits model and calculated results based on experiments at two different temperatures are decreased by 84.45% and 62.94%, respectively. The results provide a controllable method of thermoelectric characteristics with high accuracy, which can be employed for early thermometric performance estimation for TEC design.

  12. Robotic Partial Nephrectomy Using Robotic Bulldog Clamps

    OpenAIRE

    2011-01-01

    Background and Objectives: The need for a skilled assistant to perform hilar clamping during robotic partial nephrectomy is a potential limitation of the technique. We describe our experience using robotic bulldog clamps applied by the console surgeon for hilar clamping. Methods: A total of 60 consecutive patients underwent robotic partial nephrectomy, 30 using laparoscopic bulldog clamps applied by the assistant and 30 using robotic bulldog clamps applied with the robotic Prograsp instrument...

  13. 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 ...

  14. Trends in Aortic Clamp Use During Coronary Artery Bypass Surgery: The Effect of Aortic Clamping Strategies on Neurologic Outcomes

    Science.gov (United States)

    Daniel, William T.; Kilgo, Patrick; Puskas, John D.; Thourani, Vinod H.; Lattouf, Omar M.; Guyton, Robert A.; Halkos, Michael E.

    2013-01-01

    Objective The purpose of this study was to determine the impact of different clamping strategies during CABG on the incidence of postoperative stroke. Methods In this case-control study, all patients at Emory hospitals from 2002–2009 with postoperative stroke after isolated CABG (N=141) were matched 1:4 to a contemporaneous cohort of patients without postoperative stroke (N=565). Patients were matched according to the Society of Thoracic Surgeons (STS) Predicted Risk of Postoperative Stroke (PROPS), which is based on 26 variables. On- (ONCAB) and off-pump (OPCAB) patients were matched separately. Multiple logistic regression analysis with adjusted odds ratios (OR) was performed to identify operative variables associated with postoperative stroke. Results Among the ONCAB cohort, the single cross-clamp technique was associated with a decreased risk of stroke compared to the double clamp (cross clamp + partial clamp) technique (OR=0.385, p=0.044). Within the OPCAB cohort, there was no significant difference in stroke according to clamp use. Epiaortic ultrasound of the ascending aorta increased from 45.3% in 2002 to 89.4% in 2009. From 2002–2009, clamp use decreased from 97.7% of cases to 72.7%. Conclusions During ONCAB, the use of a single cross-clamp compared to the double clamp technique decreases the risk of postoperative stroke. The use of any aortic clamp has decreased and epiaortic ultrasound use has increased from 2002–2009, indicating a change in operative technique and surgeon awareness of the potential complications associated with manipulation of the aorta. PMID:23477689

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

    Directory of Open Access Journals (Sweden)

    Yao Xiaolong

    2015-01-01

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

  16. Study of Energy Losses in High-Voltage Induction Motor Electric Drive

    Directory of Open Access Journals (Sweden)

    Svilen Rachev

    2016-10-01

    Full Text Available The dynamic behavior during operation of the high-voltage induction motor electric drive has been studied by means of mathematical model developed. The purpose is to draw out more clearly picture of operation of high-voltage induction motor drives. The system of differential equations has been transformed and solved using suitable software. As a result the values of the energy losses components in the induction motor have been obtained according to different values of supply voltage and factor of inertia. Some of the study results have been presented graphically. An analysis has been made and conclusions from the results obtained have been done.

  17. Low voltage electrodeposition of CN x films and study of the effect of the deposition voltage on bonding configurations

    Science.gov (United States)

    Sreejith, K.; Nuwad, J.; Pillai, C. G. S.

    2005-10-01

    Carbon nitride (CN x) films were deposited from acetonitrile at low voltage (150-450 V) through electrodeposition. The films were characterized by atomic force microscopy (AFM), Raman spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. AFM investigations revealed that the grain size was ˜200 nm and roughness was ˜10 nm. The films were found to be continuous and close packed. IR spectra revealed existence of strong sp 3, sp 2 type bonding and weak sp type carbon nitrogen bonds and these bonds were found to increase with voltage. The fraction of sp 3-bonded species in the sample increased in low voltage range and after reaching maximum at 350 V, decreased for higher voltages. However, the concentration of sp 2 CN ring structures in the film increased with increasing voltage. Also, the peak width decreased at low voltages reaching a minimum and increased thereafter. It was observed that the voltage dependent increase in the concentration of polymeric type sp 2 CN (chain) structures was much more pronounced than that of graphitic type sp 2 CN (ring) structures. Raman spectra showed the presence of both the D and G bands. The shift in the G band indicated the presence of nitrogen in the film. The I D/I G ratio was found to increase with the incorporation of nitrogen. Auger electron spectroscopy (AES) showed a clear increase in the nitrogen content with increase in the voltage. The formation of the film could be explained on the basis of dissociation of electrolyte under applied voltage.

  18. Low voltage electrodeposition of CN {sub x} films and study of the effect of the deposition voltage on bonding configurations

    Energy Technology Data Exchange (ETDEWEB)

    Sreejith, K. [Novel Materials and Structural Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Nuwad, J. [Novel Materials and Structural Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Pillai, C.G.S. [Novel Materials and Structural Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)]. E-mail: cgspil@apsara.barc.ernet.in

    2005-10-15

    Carbon nitride (CN {sub x}) films were deposited from acetonitrile at low voltage (150-450 V) through electrodeposition. The films were characterized by atomic force microscopy (AFM), Raman spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. AFM investigations revealed that the grain size was {approx}200 nm and roughness was {approx}10 nm. The films were found to be continuous and close packed. IR spectra revealed existence of strong sp{sup 3}, sp{sup 2} type bonding and weak sp type carbon nitrogen bonds and these bonds were found to increase with voltage. The fraction of sp{sup 3}-bonded species in the sample increased in low voltage range and after reaching maximum at 350 V, decreased for higher voltages. However, the concentration of sp{sup 2} CN ring structures in the film increased with increasing voltage. Also, the peak width decreased at low voltages reaching a minimum and increased thereafter. It was observed that the voltage dependent increase in the concentration of polymeric type sp{sup 2} CN (chain) structures was much more pronounced than that of graphitic type sp{sup 2} CN (ring) structures. Raman spectra showed the presence of both the D and G bands. The shift in the G band indicated the presence of nitrogen in the film. The I{sub D}/I{sub G} ratio was found to increase with the incorporation of nitrogen. Auger electron spectroscopy (AES) showed a clear increase in the nitrogen content with increase in the voltage. The formation of the film could be explained on the basis of dissociation of electrolyte under applied voltage.

  19. 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. METH...

  20. 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

  1. The early effects of delayed cord clamping in term infants born to Libyan mothers

    NARCIS (Netherlands)

    Emhamed, Musbah Omar; van Rheenen, Patrick; Brabin, Bernard J

    2004-01-01

    This study was conducted to evaluate the haematological effects of the timing of umbilical cord clamping in term infants 24 h after birth in Libya. Mother-infant pairs were randomly assigned to early cord clamping (within 10s after delivery) or delayed clamping (after the cord stopped pulsating). Ma

  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. 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.

  4. High voltage transmission lines studies with the use of artificial intelligence

    Energy Technology Data Exchange (ETDEWEB)

    Ekonomou, L. [A.S.PE.T.E. - School of Pedagogical and Technological Education, Department of Electrical Engineering Educators, N. Heraklion, 141 21 Athens (Greece)

    2009-12-15

    The paper presents an alternative approach for the studies of high voltage transmission lines based on artificial intelligence and more specifically artificial neural networks (ANNs). In contrast to the existing conventional-analytical techniques and simulations which are using in the calculations empirical and/or approximating equations, this approach is based only on actual field data and actual measurements. The proposed approach is applied on high voltage transmission lines in order to calculate the lightning outages, on grounding systems in order to assess the grounding resistance and on high voltage transmission lines' polluted insulators in order to estimate the critical flashover voltage. The obtained results are very close to the actual ones for all three case studies, something which clearly implies that the ANN approach is well working and has an acceptable accuracy, constituting an additional tool of electric engineers. (author)

  5. Effect of delayed umbilical cord clamping on blood gas analysis.

    Science.gov (United States)

    Valero, Javier; Desantes, Domingo; Perales-Puchalt, Alfredo; Rubio, Juan; Diago Almela, Vicente J; Perales, Alfredo

    2012-05-01

    To ascertain if there are differences in umbilical cord blood gas analysis between immediate and delayed cord clamping. In a prospective observational study on 60 vaginally delivered healthy term newborns, we sampled umbilical cord blood immediately after delivery and at the time umbilical cord pulsation spontaneously ceased. There were significant decreases in pH, oxygen saturation (sO(2)), glycemia, oxygen content (ctO(2)), bicarbonate (HCO(3)(-)) and base excess (BE). Lactate and [Formula: see text] increased. Delayed cord clamping pH correlated with immediate cord clamping pH, [Formula: see text] , ctHb, sO(2) and time (r(2)=0.77, pcord clamping lactate was associated with immediate cord clamping lactate and time (r(2)=0.83, pcord clamping alters acid-base parameters and lactate values compared to immediate cord clamping. Those variations depend mainly on time, prior pH and lactate. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  6. Comparative Study of Breakdown Voltage of Mineral, Synthetic and Natural Oils and Based Mineral Oil Mixtures under AC and DC Voltages

    Directory of Open Access Journals (Sweden)

    Abderrahmane Beroual

    2017-04-01

    Full Text Available This paper deals with a comparative study of AC and DC breakdown voltages of based mineral oil mixtures with natural and synthetic esters mainly used in high voltage power transformers. The goal was to analyze the performances of oil mixtures from the dielectric withstand point of view and to predict the behavior of transformers originally filled with mineral oil and re-filled with synthetic or natural ester oils when emptied for maintenance. The study concerns mixtures based on 20%, 50%, and 80% of natural and synthetic ester oils. AC breakdown voltages were measured using a sphere-sphere electrode system according to IEC 60156 specifications; the same specification was adopted for DC measurements since there is no standard specifications for this voltage waveform. A statistical analysis of the mean values, standard deviations, and histograms of breakdown voltage data was carried out. The Normal and Weibull distribution functions were used to analyze the experimental data and the best function that the data followed was used to estimate the breakdown voltage with risk of 1%, 10%, and 50% probability. It was shown that whatever the applied voltage waveforms, ester oils always have a significantly higher breakdown voltage than mineral oil. The addition of only 20% of natural or synthetic ester oil was sufficient to considerably increase the breakdown voltage of mineral oil. The dielectric strength of such a mixture is much higher than that of mineral oil alone and can reach that of ester oils. From the point of view of dielectric strength, the mixtures constitute an option for improving the performance of mineral oil. Thus, re-filling of transformers containing up to 20% mineral oil residues with ester oils, does not present any problem; it is even advantageous when considering only the breakdown voltage. Under AC, the mixtures with natural ester always follow the behavior of vegetable oil alone. With the exception of the 20% mixture of natural

  7. Study of the interaction between space plasma and high voltage solar array

    OpenAIRE

    Iwasa, Minoru; TANAKA, KOJI; Sasaki, Susumu; ODAWARA, OSAMU; 岩佐 稔; 田中 孝治; 佐々木 進; 小田原 修

    2006-01-01

    We are studying the problems associated with high voltage power systems in space. Especially we are interested in the potential distribution of the solar array that is resistant to the electrical discharge. We have carried out experiment on the interaction between the space plasma and the high voltage solar array. An array of electrodes distributed on a dielectric material was used to simulate the inter-connectors of the solar array panel in space environment. One of major concerns in the usa...

  8. Study of the plasma interference with high voltage electrode array for space power application

    OpenAIRE

    Iwasa, Minoru; TANAKA, KOJI; Sasaki, Susumu; ODAWARA, OSAMU; 岩佐 稔; 田中 孝治; 佐々木 進; 小田原 修

    2005-01-01

    We are studying the problems associated with high voltage power systems in space. Especially we are interested in the potential distribution of the solar array that is resistant to the electrical discharge. We have carried out experiments on the interaction between the high voltage solar array and the ambient plasma. In the experiment, an array of electrodes distributed on the insulation panel was used to simulate the inter-connectors of the solar array. An electrode array without the insulat...

  9. 三电平中点钳位电压型逆变器带不平衡负载时的复合控制策略%Integrate Control Strategy for Three-level Neutral-point Clamped Voltage Source Inverter with Unbalanced Load

    Institute of Scientific and Technical Information of China (English)

    肖飞; 谢桢; 吕昊

    2013-01-01

    In order to improve the wave of voltage, a delay signal cancel(DSC) method has been used to distinguish and control the positive and negative sequence components. However, while reinforcing the voltage waveform, the method increases the imbalance of the current, which results in seriously neutral-point voltage oscillating, under the space vector pulse width modulation (SVPWM). Thus, impact of the negative sequence current to neutral-point voltage oscillation is calculated. The results show that the neutral-point control ability could be increased or decreased with the negative sequence component increasing, which is mostly depended on the power factor. When the modulate proportion is bigger than 0. 5, the neutral-point control ability can be descend to zero because of the inconsonance between the power factor and negative sequence gene. Moreover, the boundary of the ability to control the unbalance by controlling the redundant voltage small vectors is found. Therefore the neutral-point control SVPWM is built. Plus, a integrate control strategy for three-level neutral-point clamped (NPC) voltage source inverter with unbalanced load based on distinguishing and controlling the positive and negative sequence components by DSC is put forward. Simulation exhibit that by the presented method, the negative sequence voltage can be restrained, and the negative sequence current makes the neutral-point unbalanced, while the voltage fluctuation at the neutral-point is controlled by the integrate control strategy. It is proved that under the integrated control strategy, three-level NPC voltage source inverter( VSI) performs well with unbalance load.%为了改善不平衡负载条件下三电平中点钳位型(NPC)电压型逆变器的输出电压波形,采用了延迟信号撤销法(DSC)分离出正序和负序电压分量分别进行控制.但此方法在修正了电压波形的同时,会进一步增加输出电流的不对称性,导致在空间矢量脉宽调制算法(SVPWM)

  10. Avoiding aortic clamping during CABG reduces postoperative stroke

    Science.gov (United States)

    Moss, Emmanuel; Puskas, John D; Thourani, Vinod H; Kilgo, Patrick; Chen, Edward P; Leshnower, Bradley G; Lattouf, Omar M; Guyton, Robert A.; Glas, Kathryn E; Halkos, Michael E.

    2014-01-01

    Objective The purpose of this study was to determine whether the incidence of postoperative stroke (PS) could be reduced by eliminating aortic clamping during CABG. Methods From 2002–2013, 12,079 patients underwent primary, isolated CABG at a single US academic institution. Aortic manipulation was completely avoided by using in-situ internal mammary arteries for inflow in 1,552 (12.9%) patients (no-touch), a clampless facilitating device (CFD) was used for proximal anastomoses in 1,548 (12.8%) patients, and aortic clamping was used in 8,979 (74.3%) patients. These strategies were assessed in a logistic regression model controlling for relevant variables. Results The overall incidence of PS was 1.4% (n=165), with an unadjusted incidence of 0.6% (n=10) in the no-touch group, 1.2% (n=18) in the CFD group, and 1.5% (n=137) in the clamp group (p<0.01 for no-touch vs clamp). The ratio of observed to expected stroke rate increased as the degree of aortic manipulation increased, from 0.48 in the no-touch group, to 0.61 in the CFD group, and 0.95 in the clamp group. Aortic clamping was independently associated with an increase in PS compared to a no-touch technique (AOR 2.50, p<0.01). When separated by CPB utilization, both the off-pump partial clamp and on-pump cross-clamp techniques increased the risk of PS compared to no-touch (AOR 2.52, p<0.01 and AOR 4.25, p<0.001, respectively). Conclusion A no-aortic touch technique has the lowest risk for postoperative stroke for patients undergoing CABG. Clamping the aorta during CABG increases the risk of PS, regardless of the severity of aortic disease. PMID:25293356

  11. A comparative study of different transformer connections for railway power supply- mitigation of voltage unbalance

    DEFF Research Database (Denmark)

    Firat, Gurkan; Yang, Guangya; Ali Hussain Al-Ali, Haider

    2015-01-01

    The railway represents a large power consumer that can cause uneven loading of the phases in the high voltage grid. These unbalanced loads supplied by the utility may lead to voltage unbalance problems in the system and thereby affects the other consumers connected to the same network. It is fact...... that, voltage unbalance appears mainly as a result of unbalanced currents at the points of common coupling drawn by unevenly distributed loads. Because of a significant amount of negative sequence current injected to the system, the power system components will suffer from consequent negative effects...... such as overheating, additional losses of lines and transformers, interference with communication systems etc. This paper presents a comparative study of some transformer connections which commonly used in railway supplying AC traction loads, for voltage unbalance mitigations. Simulations for comparison...

  12. 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.

  13. Vibration of an eccentrically clamped annular plate

    Science.gov (United States)

    Tseng, J.-G.; Wickert, J. A.

    1994-04-01

    Small amplitude vibration of an eccentric annular plate, which is free along its outer edge and clamped along the interior, is investigated through experimental and analytical methods. A disk with this geometry, or a stacked array in which the clamping and symmetry axes of each disk are nominally coincident, is common in data storage and brake systems applications. In the present case, the geometric imperfections on the boundary can have important implications for the disk's dynamic response. Changes that occur in the natural frequency spectrum, the mode shapes, and the free response under eccentric mounting are studied through laboratory measurements and an approximate discrete model of the plate. The natural frequencies and modes are found through global discretization of the Kamke quotient for a classical thin plate. For the axisymmetric geometry, the natural frequencies of the sine and cosine vibration modes for a specified number of nodal diameters are repeated. With increasing eccentricity, on the other hand, each pair of repeated frequencies splits at a rate that depends on the number of nodal diameters. Over a range of clamping and eccentricity ratios, the model's predictions are compared to the measured results.

  14. Prehospital Emergency Inguinal Clamp Controls Hemorrhage in Cadaver Model

    Science.gov (United States)

    2013-07-01

    the CRoC preassembled for quick use. The clamp compresses the casualty’s tissues and is unat- tached to things like a litter. When screwed down, it is...for use on the battlefield to control difficult bleeds in the inguinal area. Study Design The study design was a sequence of experiments of clamp...temperature 4 hours before testing. The torso was rotated onto a wood block to intubate the aorta through a left thoracotomy incision. The thoracic aorta

  15. Modeling of Wind Turbines Equipped with Induction Machines for Voltage Profile Studies Using PSCAD

    Directory of Open Access Journals (Sweden)

    T. Abedinzadeh

    2012-12-01

    Full Text Available As a result of increasing environmental concern, more and more electricity is generated from wind turbines. Therefore, adequate models to study the impact of wind turbines on electrical power system behavior are needed. One of the most important considerations is the effect of wind turbines on the voltage profile, i.e. the induced slow voltage variations, which are the subject of this paper. The wind turbines can be operated in two modes: constant-speed and variable-speed. Each one of these cases has different impact on steady state voltage of distribution grids. For evaluation of these impacts, SCIG generator has been simulated that works in constant-speed operation and DFIG generator that is used in a variable-speed turbine. Variable-speed wind turbines can be controlled in two ways. They can produce power with constant power factor or they control magnitude of voltage of PCC. PSCAD/EMTDC simulation program is used to investigate the impact of these turbines on a distribution grid. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation and control schemes. Also, it is shown that voltage control scheme has better results and improves the voltage profile considerably.

  16. 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.

  17. 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/Clamp.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 ...

  18. Timing of umbilical cord clamping: new thoughts on an old discussion.

    Science.gov (United States)

    Arca, Gemma; Botet, Francesc; Palacio, Montse; Carbonell-Estrany, Xavier

    2010-11-01

    The optimal time to clamp the umbilical cord in preterm and full-term neonates after birth continues to be a matter of debate. A review of randomised controlled trials comparing the effects of early versus late cord clamping on maternal and infant outcomes was performed to assess data in favor of immediate or delayed clamping. Although there is no conclusive evidence, delayed cord clamping seems to be beneficial in preterm and full-term neonates without compromising the initial postpartum adaptation phase or affecting the mother in the short term. However, further randomised clinical studies are needed to confirm the benefits of delayed cord clamping.

  19. Delayed umbilical cord clamping in premature neonates.

    Science.gov (United States)

    Kaempf, Joseph W; Tomlinson, Mark W; Kaempf, Andrew J; Wu, YingXing; Wang, Lian; Tipping, Nicole; Grunkemeier, Gary

    2012-08-01

    Delayed umbilical cord clamping is reported to increase neonatal blood volume. We estimated the clinical outcomes in premature neonates who had delayed umbilical cord clamping compared with a similar group who had early umbilical cord clamping. This was a before-after investigation comparing early umbilical cord clamping with delayed umbilical cord clamping (45 seconds) in two groups of singleton neonates, very low birth weight (VLBW) (401-1,500 g) and low birth weight (LBW) (greater than 1,500 g but less than 35 weeks gestation). Neonates were excluded from delayed umbilical cord clamping if they needed immediate major resuscitation. Primary outcomes were provision of delivery room resuscitation, hematocrit, red cell transfusions, and the principle Vermont Oxford Network outcomes. In VLBW neonates (77 delayed umbilical cord clamping, birth weight [mean±standard deviation] 1,099±266 g; 77 early umbilical cord clamping 1,058±289 g), delayed umbilical cord clamping was associated with less delivery room resuscitation, higher Apgar scores at 1 minute, and higher hematocrit. Delayed umbilical cord clamping was not associated with significant differences in the overall transfusion rate, peak bilirubin, any of the principle Vermont Oxford Network outcomes, or mortality. In LBW neonates (172 delayed umbilical cord clamping, birth weight [mean±standard deviation] 2,159±384 g; 172 early umbilical cord clamping 2,203±447 g), delayed umbilical cord clamping was associated with higher hematocrit and was not associated with a change in delivery room resuscitation or Apgar scores or with changes in the transfusion rate or peak bilirubin. Regression analysis showed increasing gestational age and birth weight and delayed umbilical cord clamping were the best predictors of higher hematocrit and less delivery room resuscitation. Delayed umbilical cord clamping can safely be performed in singleton premature neonates and is associated with a higher hematocrit, less delivery room

  20. Study of seismic response and vibration control of High voltage electrical equipment damper based on TMD

    Science.gov (United States)

    Liu, Chuncheng; Wang, Chongyang; Mao, Long; Zha, Chuanming

    2016-11-01

    Substation high voltage electrical equipment such as mutual inductor, circuit interrupter, disconnecting switch, etc., has played a key role in maintaining the normal operation of the power system. When the earthquake disaster, the electrical equipment of the porcelain in the transformer substation is the most easily to damage, causing great economic losses. In this paper, using the method of numerical analysis, the establishment of a typical high voltage electrical equipment of three dimensional finite element model, to study the seismic response of a typical SF6 circuit breaker, at the same time, analysis and contrast the installation ring tuned mass damper (TMD damper for short), by changing the damper damping coefficient and the mass block, install annular TMD vibration control effect is studied. The results of the study for guiding the seismic design of high voltage electrical equipment to provide valuable reference.

  1. The timing of cord clamping and oxidative stress in term newborns.

    Science.gov (United States)

    Díaz-Castro, Javier; Florido, Jesus; Kajarabille, Naroa; Garrido-Sánchez, Maria; Padilla, Carmen; de Paco, Catalina; Navarrete, Luis; Ochoa, Julio J

    2014-08-01

    Clamping and cutting of the umbilical cord is the most prevalent of all operations, but the optimal timing of cord clamping is controversial, with different timings offering advantages and disadvantages. This study, for the first time, compares the influence of early and late cord clamping in correlation with oxidative stress and inflammation signaling, Because cord clamping timing may have a significant influence on placenta-to-infant blood transfer, thereby modifying oxygenation of maternal and fetal tissues, and on the transfer of inflammatory mediators throughout the placenta. Sixty-four pregnant subjects were selected at the Gynecology and Obstetrics Services Department of the Clinico San Cecilio Hospital, Granada, Spain, based on disease-free women who experienced a normal course of pregnancy and a spontaneous, vaginal, single delivery. Half of the subjects had deliveries with early-clamped newborn infants (at 10 s), and the other half had late-clamped deliveries (at 2 min). Erythrocyte catalase activity was significantly greater in the late-clamped group than in the early-clamped group (P umbilical vein and P clamped group compared with the early-clamped group (P cord clamping, produced by an increase in antioxidant capacity and moderation of the inflammatory-mediated effects induced during delivery of term neonates. Copyright © 2014 by the American Academy of Pediatrics.

  2. Photoinduced surface voltage mapping study for large perovskite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaojing; Liu, Yucheng; Gao, Fei; Yang, Zhou [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi' an 710062 (China); Liu, Shengzhong, E-mail: liusz@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi' an 710062 (China); Dalian Institute of Chemical Physics, iChEM, Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian 116023 (China)

    2016-05-02

    Using a series of illumination sources, including white light (tungsten-halogen lamp), 445-nm, 532-nm, 635-nm, and 730-nm lasers, the surface photovoltage (SPV) images were mapped for centimeter-sized CH{sub 3}NH{sub 3}PbX{sub 3} (X = Cl, Br, I) perovskite single crystals using Kelvin probe force microscopy. The significant SPV signals were observed to be wavelength-dependent. We attribute the appreciable SPV to the built-in electric field in the space charge region. This study shines light into the understanding of photoinduced charge generation and separation processes at nanoscale to help advance the development of perovskite solar cells, optoelectronics, laser, photodetector, and light-emitting diode (LED).

  3. Photoinduced surface voltage mapping study for large perovskite single crystals

    Science.gov (United States)

    Liu, Xiaojing; Liu, Yucheng; Gao, Fei; Yang, Zhou; Liu, Shengzhong Frank

    2016-05-01

    Using a series of illumination sources, including white light (tungsten-halogen lamp), 445-nm, 532-nm, 635-nm, and 730-nm lasers, the surface photovoltage (SPV) images were mapped for centimeter-sized CH3NH3PbX3 (X = Cl, Br, I) perovskite single crystals using Kelvin probe force microscopy. The significant SPV signals were observed to be wavelength-dependent. We attribute the appreciable SPV to the built-in electric field in the space charge region. This study shines light into the understanding of photoinduced charge generation and separation processes at nanoscale to help advance the development of perovskite solar cells, optoelectronics, laser, photodetector, and light-emitting diode (LED).

  4. Voltage and capacity control of polyaniline based organic cathodes: An ab initio study

    Science.gov (United States)

    Chen, Yingqian; Manzhos, Sergei

    2016-12-01

    Polyaniline (PANI) is a promising organic cathode material for electrochemical batteries. Its specific capacity is limited by irreversible formation of pernigraniline base, and its energy density is limited by the voltage which could be improved. We present an ab initio study of PANI and PANI functionalized with functional groups which lead to increased voltage and stabilization of the pernigraniline salt. Specifically, the oxidation potential achieved by functionalization with CN on the nitrogen is computed to be 1.3 V higher than that of pristine PANI oligomer, leading to a higher voltage, and the formation of the pernigraniline base is predicted to be simultaneously suppressed, leading to a higher reversible capacity. Therefore, functionalized PANI could be a promising candidate organic cathode for Li-ion batteries.

  5. Study the flashover voltage for outdoor polymer insulators under desert climatic conditions

    Directory of Open Access Journals (Sweden)

    L.S. Nasrat

    2013-06-01

    Results showed that flashover voltage reaches to 38 kV for samples without filler and 47 kV for samples containing 50% of ATH filler in dry condition. A comparison between inorganic fillers under various environmental conditions showed higher flashover voltage values for samples containing ATH filler than that of samples containing H3BO3 and Mg(OH2 fillers at all filler concentrations. Flashover voltage increases 24% by adding ATH filler for polyester samples under sandstorm conditions. Also, in this study, the effects of sandstorm, ultra violet (UV radiation, mechanical strength (compressive and tensile strengths and thermal performance with respect to surface of the sample under test have been investigated in detail.

  6. Internal voltage control of hydrogen-oxygen fuel cells: Feasibility study

    Science.gov (United States)

    Prokopius, P. R.

    1975-01-01

    An experimental study was conducted to assess the feasibility of internal voltage regulation of fuel cell systems. Two methods were tested. In one, reactant partial pressure was used as the voltage control parameter and in the other reactant total pressure was used for control. Both techniques were breadboarded and tested on a single alkaline-electrolyte fuel cell. Both methods were found to be possible forms of regulation, however, of the two the total pressure technique would be more efficient, simpler to apply and would provide better transient characteristics.

  7. 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.

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

    Science.gov (United States)

    Xia, Wei; Peng, Guo-Yi; Sheng, Jiang-Tao; Zhu, Fang-Fang; Guo, Jing-Fang; Chen, Wei-Qiang

    2015-04-01

    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.

  9. 双层板簧夹持的直线型超声电机%Study on the Linear Ultrasonic Motor Clamped by Double Leaf Springs

    Institute of Scientific and Technical Information of China (English)

    于会民; 王寅; 陈乾伟; 黄卫清

    2011-01-01

    The existing problems of the linear ultrasonic motor clamping device have been analyized in this paper. A new clamping scheme based on the the doulbe leaf springs has been designed for the V-shape stator with the double amplitude amplifier pole. The double leaf spring structure clamping device can limit the degree of freedom of the stator along the driving direction and accordingly the mechanical properties have been improved significantly,in addition, the two-tier parallel structure was an effective solution to the tortuosity of the stator and accordingly the stability of the motor has been improved significantly. The maximum output force, maximum power and the maximum efficiency of the motor have been up to 17. 7 N,0. 67 W and 19. 7% respectively.%分析了目前直线型超声电机夹持装置存在的问题,并针对双变幅杆V形定子结构提出了双层板簧夹持方案.双层板簧结构可限制定子沿驱动方向的自由度,从而提高了电机的机械性能,其双层平行结构可有效地解决定子工作过程中的扭转,提高了电机的稳定性,电机最大输出力达17.7 N,最大功率为0.67 W.最高效率为19.7%.

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

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

    2016-01-01

    reliability. Furthermore, a capacitor voltage control strategy by alternating two operation modes of the proposed modulation strategy is proposed to balance the voltage of the flying capacitor, which ensures multi-level voltages producing. Finally, the performance of the proposed converter and control......Multi-level converters are getting more and more attentions because of their obvious merits such as lower voltage stress and harmonic, smaller size of output filters, and so on. In this paper, a five-level active-neutral-point-clamped (5L-ANPC) dc/dc converter is proposed for power transfer...

  11. Optimization of a clamped plate silencer.

    Science.gov (United States)

    Wang, Chunqi; Han, Jun; Huang, Lixi

    2007-02-01

    A previous theoretical study [L. Huang, J. Acoust. Soc. Am. 119, 2628-2638 (2006)] shows that, in a duct, a simply supported plate covering a side-branch rigid cavity can function effectively as a wave reflector over a broad range of low to medium frequencies. In this study, analytical formulation is extended to the boundary condition of clamped plate, which is easier to implement in practice. The theoretical model is tested experimentally using balsawood, which has a very high stiffness to mass ratio. The spectral peaks and shapes of the measured TL are in agreement with those calculated theoretically, attempts are also made to account for the considerable sound absorption in the rig. Further numerical studies based on the validated model show that, for a uniform plate, the optimal stopband is narrower and the lower band limit is worse than that of the simply supported configuration. However, a wave reflector using nonuniform, clamped plates with thinner ends out-performs the simply supported configuration in every aspect. Analyses show that the improvement is attributed to the increased acoustic radiation efficiency over the bulk length of the nonuniform plate, which behaves more like a rigid plate.

  12. Delayed Umbilical Cord Clamping in the 21st Century: Indications for Practice.

    Science.gov (United States)

    Bayer, Kimberly

    2016-02-01

    Health care providers have debated the timing of umbilical cord clamping since the days of Aristotle. Delayed cord clamping was the mainstay of practice until about the 1950s when it was changed to immediate clamping on the basis of a series of blood volume studies combined with the introduction of active management of the third stage of labor. However, in recent years, several systematic reviews advise that delayed cord clamping should be used in all births for at least 30 to 60 seconds. The purpose of this article is to discuss the physiology of umbilical cord clamping, the potential benefits and adverse effects of delayed cord clamping, and how this affects the advanced practice nurse. A search of PubMed, Cochrane Reviews, and Clinical Key was used to find relevant research on the topic of umbilical cord clamping. Potential benefits of delayed cord clamping include decreased frequency of iron-deficiency anemia in the first year of life with improved neurodevelopmental outcomes in term infants, reduced need for blood transfusions, possible autologous transfusion of stem cells, and a decreased incidence of intraventricular hemorrhage. Apprehension exists regarding the feasibility of the practice as well as the potential hindrance of immediate resuscitation. There is a need to begin to look for populations for which delayed cord clamping can be implemented. Recommendations are inconsistent on the patient population and timing; therefore, further studies are needed to understand the multiple variables that affect timing of umbilical cord clamping.

  13. A voltage-dependent persistent sodium current in mammalian hippocampal neurons

    OpenAIRE

    1990-01-01

    Currents generated by depolarizing voltage pulses were recorded in neurons from the pyramidal cell layer of the CA1 region of rat or guinea pig hippocampus with single electrode voltage-clamp or tight- seal whole-cell voltage-clamp techniques. In neurons in situ in slices, and in dissociated neurons, subtraction of currents generated by identical depolarizing voltage pulses before and after exposure to tetrodotoxin revealed a small, persistent current after the transient current. These curren...

  14. Accelerated commutation for passive clamp isolated boost converters

    OpenAIRE

    2002-01-01

    An efficient and cost effective bidirectional DC/DC converter reduces switch voltage stress via accelerated commutation allowing use of a low-cost passive clamp circuit in boost mode. The converter includes a primary circuit, transformer and secondary circuit. The primary circuit takes the form of a “full bridge converter,” a “push-pull converter,” or an “L-type converter.”. The primary circuit may include a dissipator such as a snubber circuit or small buck converter. A secondary side of the...

  15. MATLAB implementation of a dynamic clamp with bandwidth >125 KHz capable of generating INa at 37°C

    Science.gov (United States)

    Clausen, Chris; Valiunas, Virginijus; Brink, Peter R.; Cohen, Ira S.

    2012-01-01

    We describe the construction of a dynamic clamp with bandwidth >125 KHz that utilizes a high performance, yet low cost, standard home/office PC interfaced with a high-speed (16 bit) data acquisition module. High bandwidth is achieved by exploiting recently available software advances (code-generation technology, optimized real-time kernel). Dynamic-clamp programs are constructed using Simulink, a visual programming language. Blocks for computation of membrane currents are written in the high-level matlab language; no programming in C is required. The instrument can be used in single- or dual-cell configurations, with the capability to modify programs while experiments are in progress. We describe an algorithm for computing the fast transient Na+ current (INa) in real time, and test its accuracy and stability using rate constants appropriate for 37°C. We then construct a program capable of supplying three currents to a cell preparation: INa, the hyperpolarizing-activated inward pacemaker current (If), and an inward-rectifier K+ current (IK1). The program corrects for the IR drop due to electrode current flow, and also records all voltages and currents. We tested this program on dual patch-clamped HEK293 cells where the dynamic clamp controls a current-clamp amplifier and a voltage-clamp amplifier controls membrane potential, and current-clamped HEK293 cells where the dynamic clamp produces spontaneous pacing behavior exhibiting Na+ spikes in otherwise passive cells. PMID:23224681

  16. Effect of temperature on the activation of myocardial KATP channel in guinea pig ventricular myocytes: a pilot study by whole cell patch clamp recording

    Institute of Scientific and Technical Information of China (English)

    JIN San-qing; NIU Li-jun; DENG Chun-yu; YAO Zhi-bin; ZHOU Ying-jie

    2006-01-01

    Background The myocardial ATP sensitive potassium channel (KATP channel) has been known for more than two decades, the properties of this channel have been intensively investigated, especially the myocardial protection effect by opening this channel. Numerous studies, including hypothermic, using KATP agonists to achieve a hyperpolarizing cardioplegic arrest, have shown a better myocardial protection than potassium arrest.However, there is no evidence showing that KATP channel could be opened by its agonists under profound hypothermia. We investigated the effect of temperature on activation of myocardial KATP channel by nicorandil.Methods Isolated ventricular myocytes were obtained by collagenase digestion of the hearts of guinea pigs and stored in KB solution at 4℃. With a steady ground current, the myocytes were perfused with 1 mmol/L nicorandil until a steady IKATP occurred. Then the cells were perfused with 1 mmol/L nicorandil plus 1 μmol/L glybenclamide. Currents signals were recorded on whole cells using patch clamp technique at several temperatures. The temperature of the bath solution around myocytes was monitored and was controlled at 4℃,10℃, 20℃, 25℃ and 35℃ respectively. About 10 cells were tested at each temperature, the cells were considered useful only when the outward current could be induced by nicorandil and blocked by glybenclamide.All data were analyzed using Graphpad PRISM 3.0 (Graphpad, San Diego, CA, USA). Nonlinear curve fitting was done in Clampfit (Axon) or Sigmaplot (SPSS).Results At 4℃, 10℃, 20℃, 25℃ and 35℃, the time needed to open the myocardial KATP channel was (81.0±0)minutes, (50.5±11.7) minutes, (28.8±2.3) minutes, (9.4±10.2) minutes and (2.3± 1.0) minutes respectively (P=0.003). The linear relationship between temperature and time needed to open the channel was y (min) =(4348.790-124.277x)/60, where y (min) is time needed to open KATP channel, x is temperature, correlation coefficient r =-0.942 (P=0

  17. Application of uniaxial confining-core clamp with hydrous pyrolysis in petrophysical and geochemical studies of source rocks at various thermal maturities

    Science.gov (United States)

    Lewan, Michael D.; Birdwell, Justin E.; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

    2013-01-01

    Understanding changes in petrophysical and geochemical parameters during source rock thermal maturation is a critical component in evaluating source-rock petroleum accumulations. Natural core data are preferred, but obtaining cores that represent the same facies of a source rock at different thermal maturities is seldom possible. An alternative approach is to induce thermal maturity changes by laboratory pyrolysis on aliquots of a source-rock sample of a given facies of interest. Hydrous pyrolysis is an effective way to induce thermal maturity on source-rock cores and provide expelled oils that are similar in composition to natural crude oils. However, net-volume increases during bitumen and oil generation result in expanded cores due to opening of bedding-plane partings. Although meaningful geochemical measurements on expanded, recovered cores are possible, the utility of the core for measuring petrophysical properties relevant to natural subsurface cores is not suitable. This problem created during hydrous pyrolysis is alleviated by using a stainless steel uniaxial confinement clamp on rock cores cut perpendicular to bedding fabric. The clamp prevents expansion just as overburden does during natural petroleum formation in the subsurface. As a result, intact cores can be recovered at various thermal maturities for the measurement of petrophysical properties as well as for geochemical analyses. This approach has been applied to 1.7-inch diameter cores taken perpendicular to the bedding fabric of a 2.3- to 2.4-inch thick slab of Mahogany oil shale from the Eocene Green River Formation. Cores were subjected to hydrous pyrolysis at 360 °C for 72 h, which represents near maximum oil generation. One core was heated unconfined and the other was heated in the uniaxial confinement clamp. The unconfined core developed open tensile fractures parallel to the bedding fabric that result in a 38 % vertical expansion of the core. These open fractures did not occur in the

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

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

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

  19. 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...

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

    KAUST Repository

    Alcheikh, N

    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.

  1. A simple method of fast extracellular solution exchange for the study of whole-cell or single channel currents using patch-clamp technique.

    Science.gov (United States)

    Hering, S; Beech, D J; Bolton, T B

    1987-10-01

    A new concentration-jump technique was devised for the rapid application of drugs to single, isolated cells attached to the base of the experimental chamber while recording from them with patch-clamp technique. Cells were placed in a micro-drop (less than 0.1 microliter) in a small inner bath which was separated from an outer bath by a ring of "Sylgard" polymer. Stable whole-cell recordings were made in the micro-drop and rapid solution exchange took place when a much larger volume of test solution from the outer bath was flooded over the Sylgard ring and mixed with the micro-drop. Complete equilibration occurred within less than 10 ms.

  2. Voltage-Activated Calcium Channels as Functional Markers of Mature Neurons in Human Olfactory Neuroepithelial Cells: Implications for the Study of Neurodevelopment in Neuropsychiatric Disorders

    Directory of Open Access Journals (Sweden)

    Héctor Solís-Chagoyán

    2016-06-01

    Full Text Available In adulthood, differentiation of precursor cells into neurons continues in several brain structures as well as in the olfactory neuroepithelium. Isolated precursors allow the study of the neurodevelopmental process in vitro. The aim of this work was to determine whether the expression of functional Voltage-Activated Ca2+ Channels (VACC is dependent on the neurodevelopmental stage in neuronal cells obtained from the human olfactory epithelium of a single healthy donor. The presence of channel-forming proteins in Olfactory Sensory Neurons (OSN was demonstrated by immunofluorescent labeling, and VACC functioning was assessed by microfluorometry and the patch-clamp technique. VACC were immunodetected only in OSN. Mature neurons responded to forskolin with a five-fold increase in Ca2+. By contrast, in precursor cells, a subtle response was observed. The involvement of VACC in the precursors’ response was discarded for the absence of transmembrane inward Ca2+ movement evoked by step depolarizations. Data suggest differential expression of VACC in neuronal cells depending on their developmental stage and also that the expression of these channels is acquired by OSN during maturation, to enable specialized functions such as ion movement triggered by membrane depolarization. The results support that VACC in OSN could be considered as a functional marker to study neurodevelopment.

  3. Dynamic Voltage Stability Studies using a Modified IEEE 30-Bus System

    Directory of Open Access Journals (Sweden)

    Oluwafemi Emmanuel Oni

    2016-09-01

    Full Text Available Power System stability is an essential study in the planning and operation of an efficient, economic, reliable and secure electric power system because it encompasses all the facet of power systems operations, from planning, to conceptual design stages of the project as well as during the systems operating life span. This paper presents different scenario of power system stability studies on a modified IEEE 30-bus system which is subjected to different faults conditions. A scenario whereby the longest high voltage alternating current (HVAC line is replaced with a high voltage direct current (HVDC line was implemented. The results obtained show that the HVDC line enhances system stability more compared to the contemporary HVAC line. Dynamic analysis using RMS simulation tool was used on DigSILENT PowerFactory.

  4. Electrostatic clamp manufactured by novel method

    NARCIS (Netherlands)

    Sligte, E. te; Storm, A.; Koster, N.B.

    2011-01-01

    Electrostatic clamps (ESCs), used in reticle and wafer handling, are presently manufactured using glass bonding and polishing technologies. We present a patented alternative concept to this process, relying on coating and etching processes rather than bonding. We manufactured a first prototype clamp

  5. 21 CFR 870.4450 - Vascular clamp.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Vascular clamp. 870.4450 Section 870.4450 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Surgical Devices § 870.4450 Vascular clamp. (a) Identification. A vascular...

  6. Comparative Analysis and Simulation of Diode Clamped & Cascaded H-Bridge Multilevel Inverter using SPWM Technique

    Directory of Open Access Journals (Sweden)

    Mohit Jain

    2015-01-01

    Full Text Available Multilevel inverters have become more popular over the years in high power medium voltage applications without the use of a transformer and with promise of less disturbance & reduced harmonic distortion. In this paper, two types of multilevel converter in three phase configuration, cascaded H-Bridge multilevel inverter (CMLI and diode clamped multilevel inverter (DCMLI of 5 and 7-level are modelled and compared in the case of feeding of a three phase squirrel cage induction motor. Here, carrier based sinusoidal pulse width modulation (SPWM technique is used as the modulation strategy. These modulation strategy include phase disposition technique (PD, phase opposition disposition technique (POD, and an alternative phase opposition disposition technique (APOD. A detailed study of the modulation technique has been carried out through MATLAB/SIMULINK for both multilevel converters and a comparative evaluation between DCMLI and CMLI using SPWM technique in terms of THD%.

  7. SIMPLIFIED SVPWM ALGORITHM BASED DIODE CLAMPED 3-LEVEL INVERTER FED DTC-IM DRIVE

    Directory of Open Access Journals (Sweden)

    C. HARI KRISHNA

    2012-05-01

    Full Text Available This paper presents a simplified space vector pulse width modulation (SVPWM based diode clamped threelevel inverter fed direct torque controlled (DTC induction motor drive. The space vector diagram of three-level inverter is simplified into two-level inverter. So the selection of switching sequences is done as conventional two-level SVPWM method. Thus, the proposed algorithm reduces the complexity involved in the PWM algorithm. To validate the proposed PWM lgorithm, several simulation studies have been carried and resultsare presented. From the results, it can be observed that the proposed algorithm reduces the total harmonic distortion (THD of the line current and line voltages when compared with the 2-level inverter fed induction motor drive.

  8. Study of DC Circuit Breaker of H2-N2 Mixture Gas for High Voltage

    Science.gov (United States)

    Shiba, Yuji; Morishita, Yukinaga; Kaneko, Shuhei; Okabe, Shigemitsu; Mizoguchi, Hitoshi; Yanabu, Satoru

    Global warming caused by CO2 etc. is a field where the concern is very high. Especially, automobile emissions are problem for it. Therefore, the hybrid car is widely development and used recently. Hybrid car used electric power and gasoline. So, the car reduces CO2. Hybrid car has engine and motor. To rotate the motor, hybrid car has battery. This battery is large capacity. Therefore, the relay should interrupt high DC current for the switch of the motor and the engine. So, hybrid car used hydrogen gas filling relay We studied interruption test for the research of a basic characteristic of hydrogen gas. DC current has not current zero point. So, it is necessary to make the current zero by high arc voltage and forcible current zero point. The loss coefficient and arc voltage of hydrogen is high. Therefore, we studied interruption test for used high arc voltage. We studied interruption test and dielectric breakdown test of air, pure Hydrogen, and Hydrogen- nitrogen mixture gas. As a result, we realized H2-N2(80%-20%) is the best gas.

  9. Time to implement delayed cord clamping.

    Science.gov (United States)

    McAdams, Ryan M

    2014-03-01

    Immediate umbilical cord clamping after delivery is routine in the United States despite little evidence to support this practice. Numerous trials in both term and preterm neonates have demonstrated the safety and benefit of delayed cord clamping. In premature neonates, delayed cord clamping has been shown to stabilize transitional circulation, lessening needs for inotropic medications and reducing blood transfusions, necrotizing enterocolitis, and intraventricular hemorrhage. In term neonates, delayed cord clamping has been associated with decreased iron-deficient anemia and increased iron stores with potential valuable effects that extend beyond the newborn period, including improvements in long-term neurodevelopment. The failure to more broadly implement delayed cord clamping in neonates ignores published benefits of increased placental blood transfusion at birth and may represent an unnecessary harm for vulnerable neonates.

  10. Umbilical cord clamping. An analysis of a usual neonatological conduct.

    Science.gov (United States)

    Papagno, L

    1998-01-01

    Here we described a critical analysis of the neonatological procedure of early cord clamping, meaning this, within 40 seconds after birth. Fifty three cases are here analysed, in which this practice was not performed, but instead a late umbilical cord clamping was done after birth or after the cord had stopped beating. Variations in hematocrito values within 24 to 36 hours after birth were studied. A transitory polycithemia, with a maximum peak 12 hours post-delivery was observed. These values returned to normal levels between 24 and 36 hours after birth. K vitamin was not administered to any of the newborns. No pathology appeared related to this transitory polycithemia. In can be concluded that the late umbilical cord clamping represents no risk to the new-born and that the pathological phenomena described under these circumstances may be attributed to the increase in K vitamin dependent coagulation factors that are induced by the routinary administration of phitonadione to all normal newborns.

  11. [Advantage of delayed umbilical cord clamping in the newborn infant].

    Science.gov (United States)

    Menget, A; Mougey, C; Thiriez, G; Riethmuller, D

    2013-09-01

    The timing of umbilical cord clamping remains controversial. Although most maternity wards use the early clamping (5-15s), randomized studies and meta-analyses have demonstrated the benefit of delayed clamping for term and preterm newborn infants over the past 10 years. Indeed, placentofetal transfusion of 20-30 ml/kg in 2-3 min improves the iron status of term infants and prevents infant hypochromic anemia. Infant anemia is a public health problem in many developing countries. For preterm newborns, placental transfusion for 45 s or milking the cord for 15 s improves cardiovascular adaptation, with better hemodynamic stability, as well as decreased intraventricular hemorrhages, need for transfusion, and late-onset sepsis. A new look at this symbolic act is needed and professionals need to be persuaded of the importance of the "wait a minute" policy for a better physiological delivery.

  12. Deciphering voltage-gated Na(+) and Ca(2+) channels by studying prokaryotic ancestors.

    Science.gov (United States)

    Catterall, William A; Zheng, Ning

    2015-09-01

    Voltage-gated sodium channels (NaVs) and calcium channels (CaVs) are involved in electrical signaling, contraction, secretion, synaptic transmission, and other physiological processes activated in response to depolarization. Despite their physiological importance, the structures of these closely related proteins have remained elusive because of their size and complexity. Bacterial NaVs have structures analogous to a single domain of eukaryotic NaVs and CaVs and are their likely evolutionary ancestor. Here we review recent work that has led to new understanding of NaVs and CaVs through high-resolution structural studies of their prokaryotic ancestors. New insights into their voltage-dependent activation and inactivation, ion conductance, and ion selectivity provide realistic structural models for the function of these complex membrane proteins at the atomic level. Published by Elsevier Ltd.

  13. Beliefs and practices of obstetric care providers regarding umbilical cord clamping.

    Science.gov (United States)

    Hill, Allyson L; Fontenot, Holly B

    2014-01-01

    The optimal timing for umbilical cord clamping after birth has yet to be established, and controversy exists. There is evidence of potentially significant health benefits of delayed cord clamping for both full-term and preterm newborns, but this practice has not been widely adopted. This column takes a second look at two recent studies in which researchers examined the beliefs and practices of obstetric care providers regarding umbilical cord clamping in North America. Nurses who are aware of the latest science and who understand both existing practice patterns as well as practice barriers to delayed clamping can be leaders in and advocates for change. © 2014 AWHONN.

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

    Institute of Scientific and Technical Information of China (English)

    Wei Xia; Guo-yi Peng; Jiang-tao Sheng; Fang-fang Zhu; Jing-fang Guo; Wei-qiang Chen

    2015-01-01

    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 expo-sure 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. Volt-age-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 corti-cal neurons by interleukin-6 is time- and dose-dependent.

  15. Combat ready clamp medic technique.

    Science.gov (United States)

    Tovmassian, Robert V; Kragh, John F; Dubick, Michael A; Baer, David G; Blackbourne, Lorne H

    2012-01-01

    Junctional hemorrhage control device use on the battlefield might be lifesaving, but little experience is reported. The purpose of the present case report is to detail prehospital use of the Combat Ready Clamp (called the CRoC by its users, Combat Medical Systems, Fayetteville, NC; Instructions for Use, 2010) in casualty care in order to increase awareness of junctional hemorrhage control. The CRoC was used to control difficult inguinal bleeding on the battlefield for an Afghani man with a hindquarter traumatic amputation. The device promptly controlled exsanguination from a critical injury when placed during rotary-wing casualty evacuation. The flight medic applied the device in 90 seconds. The device performed well without complications to control bleeding. The CRoC, a new junctional hemorrhage control device, was used as indicated on the battlefield with mechanical and physiologic success and without device problems. By controlling difficult inguinal bleeding resulting from battlefield trauma, the device facilitated casualty stabilization and delivery to a surgical facility. The device facilitated the ability of a new flight medic to focus his expertise on a critically injured battlefield casualty with demonstrable success. 2012.

  16. Thermal stiffening of clamped elastic ribbons

    Science.gov (United States)

    Wan, Duanduan; Nelson, David R.; Bowick, Mark J.

    2017-07-01

    We use molecular dynamics to study the vibrations of a thermally fluctuating two-dimensional elastic membrane clamped at both ends. We directly extract the eigenmodes from resonant peaks in the frequency domain of the time-dependent height and measure the dependence of the corresponding eigenfrequencies on the microscopic bending rigidity of the membrane, taking care also of the subtle role of thermal contraction in generating a tension when the projected area is fixed. At finite temperatures we show that the effective (macroscopic) bending rigidity tends to a constant as the bare bending rigidity vanishes, consistent with theoretical arguments that the large-scale bending rigidity of the membrane arises from a strong thermal renormalization of the microscopic bending rigidity. Experimental realizations include covalently bonded two-dimensional atomically thin membranes such as graphene and molybdenum disulfide or soft matter systems such as the spectrin skeleton of red blood cells or diblock copolymers.

  17. Study of CT head scans using different voltages: image quality evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco de Freitas C, I.; Prata M, A. [Centro Federal de Educacao Tecnologica de Minas Gerais, Centro de Engenharia Biomedica, Av. Amazonas 5253, 30421-169 Nova Suica, Belo Horizonte, Minas Gerais (Brazil); Alonso, T. C. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Pampulha, Belo Horizonte, Minas Gerais (Brazil); Santana, P., E-mail: iarapfcorrea@gmail.com [Universidade Federal de Minas Gerais, Departamento de Anatomia e Imagem, Av. Prof. Alfredo Balena 190, 30130-100 Belo Horizonte, Minas Gerais (Brazil)

    2016-10-15

    Computed tomography (CT) was introduced to medical practice in 1972. It generates images recognized by high diagnostic potential. CT allows investigation of structures in the human body inaccessible by conventional image methods, replacing invasive methods in many cases. Noise is a kind of variation of brightness observed on CT images, and it is inherent to this method. The magnitude of the noise is determined by the standard deviation of CT numbers of a region of interest in a homogeneous material. The aim of this study is to analyze the noise in head CT images generated by different acquisition protocols using four voltage values. Five different scans were performed using a female Alderson phantom and their images were analyzed with the RadiAnt software. With the average HU values and standard deviation of each scan, the values of noise were calculated in some region of interest. The obtained noise values were compared and it was observed that the 140 kV voltage promotes the in the lower noise in the image, resulting in better image quality. The results also show that the parameters, such as voltage and current, can be adjusted so that the noise can be decreased. Thus, acquisition protocols may be adapted to produce images with diagnostic quality and lower doses in patient. (Author)

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

    Directory of Open Access Journals (Sweden)

    V. Ranjith Kumar

    2013-09-01

    Full Text Available 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 cells, batteries, or ultra capacitors. This inverter provides nearly sinusoidal voltages with very low distortion, even without filtering, using fewer switching devices. In addition, the multilevel inverter can generate a high and fixed switching frequency output voltage with fewer switching losses, since only the small power cells of the inverter operate at a high switching rate. Therefore, a high performance and also efficient torque and flux controllers are obtained, enabling a DTC solution for multilevel-inverter-powered motor drives. The Pulse Width modulation technique for an inverter permits to obtain three phase system voltages, which can be applied to the controlled output. Space Vector Modulation (SVPWM principle differs from other PWM processes in the fact that all three drive signals for the inverter will be created simultaneously. The implementation of SVPWM process in digital systems necessitates less operation time and also less program memory. This project uses SVPWM technique for generation of pulses for three-level diode clamped inverter. Simulation is carried out on MATLAB-Simulink software.

  19. The Response Clamp: Functional characterization of neural systems using closed-loop control

    Directory of Open Access Journals (Sweden)

    Avner eWallach

    2013-01-01

    Full Text Available The voltage clamp method, pioneered by Hodgkin, Huxley and Katz, laid the foundations to neurophysiological research. Its core rationale is the use of closed-loop control as a tool for system characterization. A recently introduced method, the response clamp, extends the voltage clamp rationale to the functional, phenomenological level. The method consists of on-line estimation of a response variable of interest (e.g. the probability of response or its latency and a simple feedback control mechanism designed to tightly converge this variable towards a desired trajectory. In the present contribution I offer a perspective on this novel method and its applications in the broader context of system identification and characterization. First, I demonstrate how internal state variables are exposed using the method, and how the use of several controllers may allow for a detailed, multi-variable characterization of the system. Second, I discuss three different categories of applications of the method: (i exploration of intrinsically generated dynamics, (ii exploration of extrinsically generated dynamics and (iii generation of input-output trajectories. The relation of these categories to similar uses in the voltage clamp and other techniques is also discussed. Finally, I discuss the method’s limitations, as well as its possible synthesis with existing complementary approaches.

  20. Modelling and Simulation of the SVC for Power System Flow Studies: Electrical Network in voltage drop

    OpenAIRE

    Narimen Aouzellag LAHAÇANI; Boubekeur MENDIL

    2008-01-01

    The goal of any Flexible AC Transmission Systems (FACTS) devices study is to measure their impact on the state of the electrical networks into which they are introduced. Their principal function is to improve the static and dynamic properties of the electrical networks and that by increasing the margins of static and dynamic stability and to allow the power transit to the thermal limits of the lines.To study this impact, it is necessary to establish the state of the network (bus voltages and ...

  1. A comparative study for detection and measurement of voltage disturbance in online condition

    Directory of Open Access Journals (Sweden)

    Vijay Gajanan Neve

    2015-05-01

    Full Text Available Voltage disturbance is the most important power quality problem faced by many industrial customers. It includes voltage sag, swell, spikes and harmonics. Real time detection of these voltage disturbances posed various problems. This paper compares the various methods of detection of voltage sag and swells in real time on the basis of detection time, magnitude, effect of windowing and effect of sampling frequencies. The RMS, Peak, Fourier transform and Missing Voltage algorithm are introduced and discussed in them for real time implementation. Comparative analysis reveals that quantification of voltage sag and swell is possible using these measurements. The main focus is given on to these points and all the voltage sag and swell detection technique tested online with the help of advantech card data acquisition. The voltage sag and swell events are generated by using practical experimentation in laboratory.

  2. Dynamic clamp with StdpC software.

    Science.gov (United States)

    Kemenes, Ildikó; Marra, Vincenzo; Crossley, Michael; Samu, Dávid; Staras, Kevin; Kemenes, György; Nowotny, Thomas

    2011-03-01

    Dynamic clamp is a powerful method that allows the introduction of artificial electrical components into target cells to simulate ionic conductances and synaptic inputs. This method is based on a fast cycle of measuring the membrane potential of a cell, calculating the current of a desired simulated component using an appropriate model and injecting this current into the cell. Here we present a dynamic clamp protocol using free, fully integrated, open-source software (StdpC, for spike timing-dependent plasticity clamp). Use of this protocol does not require specialist hardware, costly commercial software, experience in real-time operating systems or a strong programming background. The software enables the configuration and operation of a wide range of complex and fully automated dynamic clamp experiments through an intuitive and powerful interface with a minimal initial lead time of a few hours. After initial configuration, experimental results can be generated within minutes of establishing cell recording.

  3. Molecular Mechanisms of DNA Polymerase Clamp Loaders

    Science.gov (United States)

    Kelch, Brian; Makino, Debora; Simonetta, Kyle; O'Donnell, Mike; Kuriyan, John

    Clamp loaders are ATP-driven multiprotein machines that couple ATP hydrolysis to the opening and closing of a circular protein ring around DNA. This ring-shaped clamp slides along DNA, and interacts with numerous proteins involved in DNA replication, DNA repair and cell cycle control. Recently determined structures of clamp loader complexes from prokaryotic and eukaryotic DNA polymerases have revealed exciting new details of how these complex AAA+ machines perform this essential clamp loading function. This review serves as background to John Kuriyan's lecture at the 2010 Erice School, and is not meant as a comprehensive review of the contributions of the many scientists who have advanced this field. These lecture notes are derived from recent reviews and research papers from our groups.

  4. Clamp force and alignment checking device

    Energy Technology Data Exchange (ETDEWEB)

    Spicer, John Patrick; Cai, Wayne W.; Chakraborty, Debejyo; Mink, Keith

    2017-04-11

    A check fixture measures a total clamp force applied by a welder device. The welder device includes a welding horn having a plurality of weld pads and welding anvil having a plurality of weld pads. The check fixture includes a base member operatively supporting a plurality of force sensors. The base member and the force sensors are received between the weld pads of the welding horn and the anvil pads of the welding anvil. Each force sensor is configured to measure an individual clamp force applied thereto by corresponding weld and anvil pads when the base member is received between the welding horn and the welding anvil and the welder device is in the clamped position. The individual clamp forces are used to determine whether the weld and/or anvil pads are worn or misaligned.

  5. Admittance Modeling of Voltage and Current Controlled Inverter for Harmonic Instability Studies

    DEFF Research Database (Denmark)

    Hoseinzadeh, Bakhtyar; Bak, Claus Leth

    2016-01-01

    This paper proposes an impedance/admittance based model for voltage and current controlled inverters with passive elements suitable for harmonic instability study of grid connected inverters in frequency domain. This linearized model of inverters, significantly simplifies investigation of resonance...... instability and control loop interaction of wind turbines with each other and/or with the grid, while they are installed in wind farms. The derived impedance ratio at point of common connection demonstrates how the inverters participate in harmonic stability of the grid....

  6. Comparative Studies of Different Control Strategies of a Dynamic Voltage Restorer Based on Matrix Converter

    Directory of Open Access Journals (Sweden)

    Amin Shabanpour

    2012-01-01

    Full Text Available A dynamic voltage restorer (DVR with no energy storage is studied. By using a matrix converter instead of the conventional AC/DC/AC converters, elimination of the DC-link capacitor is possible. The switching algorithm of matrix converter is the space vector modulation. There are different compensation algorithms to control the conventional DVR. These methods have been analyzed in this paper for the proposed matrix-converter-based DVR. A deep analysis through different diagrams would show the advantages or disadvantages of each compensation method. Equations for all methods are derived, and the characteristics of algorithms are compared with each other.

  7. Integration of Fuel Cell Micro-CHPs on Low. Voltage Grid: A Danish Case Study

    DEFF Research Database (Denmark)

    You, Shi; Marra, Francesco; Træholt, Chresten

    2012-01-01

    The future significance of fuel cell (FC) powered micro combined heat and power (micro-CHP) units in meeting the residential energy demands is set to increase, which may have a considerable impact on the low voltage (LV) grid. The objective of this paper is to investigate into the related technical...... issues using a Danish case study with different penetration levels of uncoordinated FC micro-CHPs. Based on the findings, it is recommended to design grid oriented integration strategies such as Virtual Power Plants (VPPs) for achieving future smart grids with a large roll out of distributed energy...

  8. Integral transform solutions of dynamic response of a clamped-clamped pipe conveying fluid

    Energy Technology Data Exchange (ETDEWEB)

    Gu Jijun; An Chen [Ocean Engineering Program, COPPE, Universidade Federal do Rio de Janeiro, CP 68508, Rio de Janeiro 21941-972 (Brazil); Duan Menglan [Offshore Oil/Gas Research Center, China University of Petroleum, Beijing 102249 (China); Levi, Carlos [Ocean Engineering Program, COPPE, Universidade Federal do Rio de Janeiro, CP 68508, Rio de Janeiro 21941-972 (Brazil); Su Jian, E-mail: sujian@nuclear.ufrj.br [Nuclear Engineering Program, COPPE, Universidade Federal do Rio de Janeiro, CP 68509, Rio de Janeiro 21941-972 (Brazil)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Dynamic response of pipe conveying fluid was studied numerically. Black-Right-Pointing-Pointer The generalized integral transform technique (GITT) was applied. Black-Right-Pointing-Pointer Numerical solutions with automatic global accuracy control were obtained. Black-Right-Pointing-Pointer Excellent convergence behavior was shown. Black-Right-Pointing-Pointer Modal separation analysis was carried out and the influence of mass ratio was analyzed. - Abstract: Analysis of dynamic response of pipe conveying fluid is an important aspect in nuclear power plant design. In the present paper, dynamic response of a clamped-clamped pipe conveying fluid was solved by the generalized integral transform technique (GITT). The governing partial differential equation was transformed into a set of second-order ordinary differential equations which is then numerically solved by making use of the subroutine DIVPAG from IMSL Library. A thorough convergence analysis was performed to yield sets of reference results of the transverse deflection at different time and spanwise position. We found good agreement between the computed natural frequencies at mode 1-3 and those obtained by previous theoretical study. Besides, modal separation analysis was carried out and the influence of mass ratio on deflection and natural frequencies was qualitatively and quantitatively assessed.

  9. INOVASI SAMBUNGAN MEKANIS MENGGUNAKAN CLAMP BAJA UNTUK TULANGAN BETON

    Directory of Open Access Journals (Sweden)

    Parmo

    2015-12-01

    Full Text Available In the last few years, Indonesian urban growth has tends to be lead to the overground space. This was caused by the significant population increasement the lackness of land availability. The phenomenon is also marked with the increasing number of high-rise buildings and skyscrapers. However, high-rise buildings and skyscrapers have the potential dangers against earthquakes, even more Indonesia lay on an earthquake-prone areas. There are two main things that need to be considered in the planning of earthquake-resistant buildings, which is strength and ductility. Deformation capability and the connection strength between the reinforcement taken into consideration in the design of earthquake-resistant structures. From the steel clamp tensile test results for D13’s mechanical connection reinforcement, it gained 270.69 Mpa for yield strength, 351.45 MPa for ultimate tensile strength and 4757 kg for maximum load with 40% elongation. As for the D16’s mechanical connection reinforcement gained 217.80 MPa for yield strength, 327 605 MPa for ultimate tensile strength and 6717 kg for maximum load with 32% elongation. This study uses two pieces of steel clamp, but in order to obtain a better result then it need to be add more clamps while increasing the steel clamp material quality.

  10. Voltage-dependent currents in microvillar receptor cells of the frog vomeronasal organ.

    Science.gov (United States)

    Trotier, D; Døving, K B; Rosin, J F

    1993-08-01

    Vomeronasal receptor cells are differentiated bipolar neurons with a long dendrite bearing numerous microvilli. Isolated cells (with a mean dendritic length of 65 microns) and cells in mucosal slices were studied using whole-cell and Nystatin-perforated patch-clamp recordings. At rest, the membrane potential was -61 +/- 13 mV (mean +/- SD; n = 61). Sixty-four per cent of the cells had a resting potential in the range of -60 to -86 mV, with almost no spontaneous action potential. The input resistance was in the G omega range and overshooting repetitive action potentials were elicited by injecting depolarizing current pulses in the range of 2-10 pA. Voltage-dependent currents were characterized under voltage-clamp conditions. A transient fast inward current activating near -45 mV was blocked by tetrodotoxin. In isolated cells, it was half-deactivated at a membrane potential near -75 mV. An outward K+ current was blocked by internal Cs+ ions or by external tetraethylammonium or Ba2+ ions. A calcium-activated voltage-dependent potassium current was blocked by external Cd2+ ions. A voltage-dependent Ca2+ current was observed in an iso-osmotic BaCl2 solution. Finally, a hyperpolarization-activated inward current was recorded. Voltage-dependent currents in these microvillar olfactory receptor neurons appear qualitatively similar to those already described in ciliated olfactory receptor cells located in the principal olfactory epithelium.

  11. The Study of Active Atoms in High-Voltage Pulsed Coronal Discharge by Optical Diagnostics

    Institute of Scientific and Technical Information of China (English)

    Liu Feng; Wang Wenchun; Wang Su; Ren Chunsheng; Wang Younian

    2005-01-01

    In this study, the emission spectra of active atoms O (3p5P → 3s5S20 777.4 nm),Ha (3P → 2S 656.3 nm) and N (3p4P → 3s4S0 742.3 nm, 744.2 nm, 746.8 nm) produced by thepositive high-voltage pulsed corona discharge (HVPCD) of N2 and H2O mixture in a needle-platereactor have successfully been recorded against a severe electromagnetic interference coming fromthe HVPCD at one atmosphere. The effects of the peak voltage, the repetition rate of pulseddischarge and the flow rate of oxygen on the production of those active atoms are investigated. Itis found that when the peak voltage and the repetition rate of the pulsed discharge are increased,the emission intensities of those active atoms rise correspondingly. And the emission intensities ofO (3p5P → 3s5S20 777.4 nm), Ha (3P → 2S 656.3 nm) and N (3p4P → 3s4S0 742.3 nm, 744.2 nm,746.8 nm) increase with the flow rate of oxygen (from 0 to 25 ml/min) and achieve a maximumvalue at a flow rate of 25 ml/min. When the flow rate of oxygen is increased further, the emissionintensities of those atoms visibly decrease correspondingly. The main physicochemical processesof interaction involved between electrons, neutrals and ions are also discussed.

  12. M. tuberculosis sliding β-clamp does not interact directly with the NAD+-dependent DNA ligase.

    Directory of Open Access Journals (Sweden)

    Vandna Kukshal

    Full Text Available The sliding β-clamp, an important component of the DNA replication and repair machinery, is drawing increasing attention as a therapeutic target. We report the crystal structure of the M. tuberculosis β-clamp (Mtbβ-clamp to 3.0 Å resolution. The protein crystallized in the space group C222(1 with cell-dimensions a = 72.7, b = 234.9 & c = 125.1 Å respectively. Mtbβ-clamp is a dimer, and exhibits head-to-tail association similar to other bacterial clamps. Each monomer folds into three domains with similar structures respectively and associates with its dimeric partner through 6 salt-bridges and about 21 polar interactions. Affinity experiments involving a blunt DNA duplex, primed-DNA and nicked DNA respectively show that Mtbβ-clamp binds specifically to primed DNA about 1.8 times stronger compared to the other two substrates and with an apparent K(d of 300 nM. In bacteria like E. coli, the β-clamp is known to interact with subunits of the clamp loader, NAD(+-dependent DNA ligase (LigA and other partners. We tested the interactions of the Mtbβ-clamp with MtbLigA and the γ-clamp loader subunit through radioactive gel shift assays, size exclusion chromatography, yeast-two hybrid experiments and also functionally. Intriguingly while Mtbβ-clamp interacts in vitro with the γ-clamp loader, it does not interact with MtbLigA unlike in bacteria like E. coli where it does. Modeling studies involving earlier peptide complexes reveal that the peptide-binding site is largely conserved despite lower sequence identity between bacterial clamps. Overall the results suggest that other as-yet-unidentified factors may mediate interactions between the clamp, LigA and DNA in mycobacteria.

  13. Structural insight into β-Clamp and its interaction with DNA Ligase in Helicobacter pylori.

    Science.gov (United States)

    Pandey, Preeti; Tarique, Khaja Faisal; Mazumder, Mohit; Rehman, Syed Arif Abdul; Kumari, Nilima; Gourinath, Samudrala

    2016-08-08

    Helicobacter pylori, a gram-negative and microaerophilic bacterium, is the major cause of chronic gastritis, gastric ulcers and gastric cancer. Owing to its central role, DNA replication machinery has emerged as a prime target for the development of antimicrobial drugs. Here, we report 2Å structure of β-clamp from H. pylori (Hpβ-clamp), which is one of the critical components of DNA polymerase III. Despite of similarity in the overall fold of eubacterial β-clamp structures, some distinct features in DNA interacting loops exists that have not been reported previously. The in silico prediction identified the potential binders of β-clamp such as alpha subunit of DNA pol III and DNA ligase with identification of β-clamp binding regions in them and validated by SPR studies. Hpβ-clamp interacts with DNA ligase in micromolar binding affinity. Moreover, we have successfully determined the co-crystal structure of β-clamp with peptide from DNA ligase (not reported earlier in prokaryotes) revealing the region from ligase that interacts with β-clamp.

  14. Fundamental-Frequency-Modulated Six-Level Diode-Clamped Multilevel Inverter for Three-Phase Stand-Alone Photovoltaic System

    Energy Technology Data Exchange (ETDEWEB)

    Ozdemir, Engin [ORNL; Ozdemir, Sule [Oak Ridge National Laboratory (ORNL); Tolbert, Leon M [ORNL

    2009-01-01

    This paper presents a fundamental-frequency-modulated diode-clamped multilevel inverter (DCMLI) scheme for a three-phase stand-alone photovoltaic (PV) system. The system consists of five series-connected PV modules, a six-level DCMLI generating fundamental-modulation staircase three-phase output voltages, and a three-phase induction motor as the load. In order to validate the proposed concept, simulation studies and experimental measurements using a small-scale laboratory prototype are also presented. The results show the feasibility of the fundamental frequency switching application in three-phase stand-alone PV power systems.

  15. Mitigation of Voltage Dip and Voltage Flickering by Multilevel D-STATCOM

    Directory of Open Access Journals (Sweden)

    M. S. Ballal

    2012-01-01

    Full Text Available The basic power quality problems in the distribution network are voltage sag (dip, voltage flickering, and the service interruptions. STATCOM is a Flexible AC Transmission Systems (FACTS technology device which can independently control the flow of reactive power. This paper presents the simulation and analysis of a STATCOM for voltage dip and voltage flickering mitigation. Simulations are carried out in MATLAB/Simulink to validate the performance of the STATCOM. A comparison between the six-pulse inverter and the five-level diode-clamped inverter is carried out for the performance of 66/11 KV distribution system.

  16. A reduction clamp for an aiming component in associated acetabular fractures

    Directory of Open Access Journals (Sweden)

    Zhang-Fu Wang

    2015-01-01

    Full Text Available Background: The treatment of acetabular fractures is complex and requires specialized equipment. However, all currently available instruments have some disadvantages. A new reduction clamp that can firmly enable reduction and not hinder subsequent fixation procedures for some special fracture types is needed. Materials and Methods: In this study, we introduce a new acetabular clamp and its preliminary clinical application in three T-shaped acetabular fractures. Results: This new clamp can successfully pull the posterior column back to the anterior column and firmly maintain the reduction. This clamp′s aiming plate can facilitate the insertion of long lag screws. The clamp is also easy to assemble and use. Conclusion: This reduction clamp is a useful instrument that can facilitate open reduction and internal fixation of acetabular fractures.

  17. Comparative study of high voltage bushing designs suitable for apparatus containing cryogenic helium gas

    Science.gov (United States)

    Rodrigo, H.; Graber, L.; Kwag, D. S.; Crook, D. G.; Trociewitz, B.

    2013-10-01

    The high voltage bushing forms a critical part of any termination on cables, transformers and other power system devices. Cryogenic entities such as superconducting cables or fault current limiters add more complexity to the design of the bushing. Even more complex are bushings designed for superconducting devices which are cooled by high pressure helium gas. When looking for a bushing suitable for dielectric cable tests in a helium gas cryostat no appropriate device could be found that fulfilled the criterion regarding partial discharge inception voltage level. Therefore we decided to design and manufacture a bushing in-house. In the present work we describe the dielectric tests and operational experience on three types of bushings: One was a modified commercially available ceramics feed through which we adopted for our special need. The second bushing was made of an epoxy resin, with an embedded copper squirrel cage arrangement at the flange, extending down about 30 cm into the cold end of the bushing. This feature reduced the electric field on the surface of the bushing to a negligible value. The third bushing was based on a hollow body consisting of glass fiber reinforced polymer and stainless steel filled with liquid nitrogen. The measurements showed that the dielectric quality of all three bushings exceeded the requirements for the intended purpose. The partial discharge (PD) data from these studies will be used for the design and fabrication of a cable termination for a specialized application on board a US Navy ship.

  18. Study of predicting breakdown voltage of stator insulation in generator based on BP neural network

    Institute of Scientific and Technical Information of China (English)

    Jiang Yuao; Zhang Aide; Liu Libing; Du Yu; Gao Naikui; Peng Zongren

    2007-01-01

    The breakdown voltage plays an important role in evaluating residual life of stator insulation in generator. In this paper, we discussed BP neural network that was used to predict the breakdown voltage of stator insulation in generator of 300 MW/18 kV. At first the neural network has been trained by the samples that include the varieties of dielectric loss factor tanδ, the partial discharge parameters and breakdown voltage. Then we tried to predict the breakdown voltage of samples and stator insulations subjected to multi-stress aging by the trained neural network. We found that it's feasible and accurate to predict the voltage. This method can be applied to predict breakdown voltage of other generators which have the same insulation structure and material.

  19. A Case Study Of Turkish Transmission System For VoltageDips

    DEFF Research Database (Denmark)

    Inan, E.; Alboyaci, B.; Bak, Claus Leth

    2009-01-01

    Power quality problems usually appear in the form of voltage sags, transients and harmonics. From these three broad categories of power quality problems, voltage dips account the most disturbances experienced by industrial customers. Voltage dips generally refer to instantaneous short...... analysis of voltage dip performance of the whole transmission system, is used to compare with results constructed fault statics from SIMPOW DIPS analysis program real data. SIMPOW DIPS software enables to calculate dip frequency for all busses and lines.......-duration voltage variations. The aim of this paper is to have an idea about voltage dip performance of Turkey Transmission System. Turkey's transmission system has 21 regions. For simulations, 2nd region, which includes Istanbul city's area is heavy loaded, is selected. For purposes of early warning and later...

  20. In-situ studies on phase transformations under electron irradiation in a high voltage electron microscope

    Indian Academy of Sciences (India)

    S Banerjee

    2003-06-01

    High voltage electron microscopy (HVEM), using electron energies adequate for causing displacements of atoms from lattice sites, is a very effective technique for studying mechanisms of solid state phase transformations and for charting the path of phase evolution in real time. This has been demonstrated in studies on chemical ordering in nickel–molybdenum alloys and on the $\\beta \\to \\omega$ displacement ordering in zirconium-niobium alloys. The enhanced diffusivity due to electron irradiation makes it possible to explore a sequence of phase evolution at low enough temperatures where even some first-order transformations are driven by free energy (G) instabilities with respect to the relevant order parameter $(\\eta)$. Specific issues addressed in these studies are reviewed in this paper.

  1. 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.

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

    Directory of Open Access Journals (Sweden)

    Qiang Zhou

    2015-12-01

    Full Text Available 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. Study on the instantaneous protection reliability of low voltage circuit breakers

    Institute of Scientific and Technical Information of China (English)

    LU Jian-guo; DU Tai-hang; LUO Yan-yan

    2007-01-01

    This paper outlines the significance of enhancing the instantaneous protection reliability of low voltage circuit breakers and describes their main failure modes. The instantaneous failure mechanism of low voltage circuit breakers was analyzed so that measures to improve instantaneous protection reliability can be determined. Furthermore, the theory of the instantaneous characteristics Calibration device for low voltage circuit breakers and the method of eliminating the non-periodic component of test current are given in detail. Finally, the test results are presented.

  4. 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...... 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...... 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...

  5. Arterial clamping leads to stenosis at clamp sites after femoropopliteal bypass surgery

    NARCIS (Netherlands)

    Vriens, Bianca H. R.; Pol, Robert A.; Hulsebos, Robin G.; van Det, Rob J.; van der Palen, Job; Zeebregts, Clark J.; Geelkerken, Robert H.

    2015-01-01

    BACKGROUND: To date, the incidence and clinical relevance of arterial stenosis at clamp sites after femoropopliteal bypass surgery is unknown. METHODS: Ninety-four patients underwent a femoropopliteal bypass in which the arterial inflow and outflow clamp sites were controlled by the Fogarty-Soft-Inl

  6. Arterial clamping leads to stenosis at clamp sites after femoropopliteal bypass surgery

    NARCIS (Netherlands)

    Vriens, Bianca H.R.; Pol, Robert A.; Hulsebos, Robin G.; Det, van Rob J.; Palen, van der Job; Zeebregts, Clark J.; Geelkerken, Robert H.

    2015-01-01

    Background To date, the incidence and clinical relevance of arterial stenosis at clamp sites after femoropopliteal bypass surgery is unknown. Methods Ninety-four patients underwent a femoropopliteal bypass in which the arterial inflow and outflow clamp sites were controlled by the Fogarty-Soft-Inla

  7. Voltage- and calcium-dependent motility of saccular hair bundles

    Science.gov (United States)

    Quiñones, Patricia M.; Meenderink, Sebastiaan W. F.; Bozovic, Dolores

    2015-12-01

    Active bundle motility, which is hypothesized to supply feedback for mechanical amplification of signals, is thought to enhance sensitivity and sharpen tuning in vestibular and auditory organs. To study active hair bundle motility, we combined high-speed camera recordings of bullfrog sacculi, which were mounted in a two-compartment chamber, and voltage-clamp of the hair cell membrane potential. Using this paradigm, we measured three types of bundle motions: 1) spontaneous oscillations which can be analyzed to measure the physiological operating range of the transduction channel; 2) a sustained quasi-static movement of the bundle that depends on membrane potential; and 3) a fast, transient and asymmetric movement that resets the bundle position and depends on changes in the membrane potential. These data support a role for both calcium and voltage in the transduction-channel function.

  8. Vascular clamping in liver surgery: physiology, indications and techniques

    Directory of Open Access Journals (Sweden)

    Cherqui Daniel

    2010-03-01

    Full Text Available Abstract This article reviews the historical evolution of hepatic vascular clamping and their indications. The anatomic basis for partial and complete vascular clamping will be discussed, as will the rationales of continuous and intermittent vascular clamping. Specific techniques discussed and described include inflow clamping (Pringle maneuver, extra-hepatic selective clamping and intraglissonian clamping and outflow clamping (total vascular exclusion, hepatic vascular exclusion with preservation of caval flow. The fundamental role of a low Central Venous Pressure during open and laparoscopic hepatectomy is described, as is the difference in their intra-operative measurements. The biological basis for ischemic preconditioning will be elucidated. Although the potential dangers of vascular clamping and the development of modern coagulation devices question the need for systemic clamping; the pre-operative factors and unforseen intra-operative events that mandate the use of hepatic vascular clamping will be highlighted.

  9. Functional dissection of synaptic circuits: in vivo patch-clamp recording in neuroscience

    Directory of Open Access Journals (Sweden)

    Can eTao

    2015-05-01

    Full Text Available Neuronal activity is dominated by synaptic inputs from excitatory or inhibitory neural circuits. With the development of in vivo patch-clamp recording, especially in vivo voltage-clamp recording, researchers can not only directly measure neuronal activity, such as spiking responses or membrane potential dynamics, but also quantify synaptic inputs from excitatory and inhibitory circuits in living animals. This approach enables researchers to directly unravel different synaptic components and to understand their underlying roles in particular brain functions. Combining in vivo patch-clamp recording with other techniques, such as two-photon imaging or optogenetics, can provide even clearer functional dissection of the synaptic contributions of different neurons or nuclei. Here, we summarized current applications and recent research progress using the in vivo patch-clamp recording method and focused on its role in the functional dissection of different synaptic inputs. The key factors of a successful in vivo patch-clamp experiment and possible solutions based on references and our experiences were also discussed.

  10. Compact, Stiff, Remotely-Actuable Quick-Release Clamp

    Science.gov (United States)

    Tsai, Ted W. (Inventor)

    2000-01-01

    The present invention provides a clamp that is compact and lightweight, yet provides high holding strength and stiffness or rigidity. The clamp uses a unique double slant interface design which provides mechanical advantages to resist forces applied to the clamp member as the load increases. The clamp allows for rapid and remote-activated release of the clamp jaws by applying only a small operating force to an over-center lock/release mechanism, such as by pulling a manual tether.

  11. Design and application of multifunctional stomach clamp

    Institute of Scientific and Technical Information of China (English)

    Yun Fu Lu; Pi Wu Li; Xir Xin Zhang

    2000-01-01

    AIM Pylorus and pyloric vagus preserving gastrectomy (PPVPG) is an efficient operation mode for treatinggastric and duodenal ulcers. For its better application and popularization, we have designed andmanufactured a special multifunctional stomach clamp.METHODS The clamp has been designed carefully in view of the different sizes of the patients' stomachsand the different starting points of Latarjer nerves so as to facilitate the execution of the present operationmode, which requires the preservation of the vagus innervated pyloric region so as to make the remnantstomach maintain its normal physiological function and the vagus branches clinging antral seromuscular flapkept in proper size so that avoiding too much remaining antral mucosa is removed to cause greater difficultyin operation. With this in view, we observed and measured the distance between the Latarjer nerves distribution and the pyloric rings of 42 patients' stomachs in the course of operations. We bent an aluminumstring 3 mm thick for each stomach according to the size of antral seromuecular flap and chose an optimalcurvature from the 42 sizes for manufacturing the clamp. The clamp is made of 3 Cr13 stainless steel,consisting of three parts, the curved head, the fastening ring and the handle. The curved head is shapedalmost exactly like the remained antral seromuscular flap. The ring at its tip when in place fastens the twosides of the clamp so that the tissue of the stomach between will be clutched by an even force. On one sideare three cuts for moving the ring upwards, each cut representing 1 mm for fastening and adjustments can bemade in view of the thickness or thinness of the tissue. The handles bend backward for fighting shy of thecuts so as to facilitate the operation.RESULTS With the stomach disassociated in the light of PPVPG procedures, the clamp may easily beapplied from the upper part of the Latarjer nerves. The following merits can be noted. ① The curving line ofthe flap can be precisely

  12. Simulation Based Performance analysis of Active Clamp DHB ZVZCS Bidirectional DC-DC converter for Low Power Applications

    Directory of Open Access Journals (Sweden)

    V.V.Subrahmanya Kumar Bhajana

    2012-06-01

    Full Text Available A novel active clamp dual half bridge DC/DC converter with bidirectional power flow is proposed in this paper and comparative analysis between active clamp DHB ZVZCS and ZVS-ZCS bidirectional DC-DC converter topologies is also presented. By adding active clamping circuits to both bridges, zero voltage and zero current switching are achieved to improve the performance of the bidirectional DC/DC converter. The principle of operation is analyzed and simulated. With the proposed active clamp ZVZCS concept, the MATLAB simulation results of the applications of the fuel cell and battery have been obtained and compared with those of ZVS-ZCS bidirectional converter. The simulation results of proposed converter is compared with the ZVS-ZCS bidirectional DC-DC converter, efficiency, switching losses are the key parameters compared.

  13. A Study on the step response characteristics in shielded resistor divider for full lightning impulse voltage

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ik Soo; Lee, Hyeong Ho [Korea Electrotehnology Research Institute, Changwon (Korea, Republic of); Cho, Jung Soo; Park, Jung Hoo [Pusan National University, Pusan (Korea, Republic of)

    1996-02-01

    This paper presents the development technology of standard shielded resistor divider for full lightning impulse voltage. The ability of large-capacity power apparatus to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently international standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisons have already completed worldwide, i.e. Europe, Japan, America etc., In this viewpoint, we have also investigated the step response of the standard shielded resistor divider, which satisfies the IEC recommendation. (author). 7 refs., 14 figs., 2 tabs.

  14. 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.

  15. 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

  16. 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...

  17. 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...

  18. Indentation metrology of clamped, ultra-thin elastic sheets

    OpenAIRE

    Vella, Dominic; Davidovitch, Benny

    2017-01-01

    We study the indentation of ultrathin elastic sheets clamped to the edge of a circular hole. This classical setup has received considerable attention lately, being used by various experimental groups as a probe to measure the surface properties and stretching modulus of thin solid films. Despite the apparent simplicity of this method, the geometric nonlinearity inherent in the mechanical response of thin solid objects renders the analysis of the resulting data a nontrivial task. Importantly, ...

  19. Canine muscle cell culture and consecutive patch-clamp measurements - a new approach to characterize muscular diseases in dogs

    Directory of Open Access Journals (Sweden)

    Schenk Henning Christian

    2012-11-01

    Full Text Available Abstract Background The recognition of functional muscular disorders, (e.g. channelopathies like Myotonia is rising in veterinary neurology. Morphologic (e.g. histology and even genetic based studies in these diseases are not able to elucidate the functional pathomechanism. As there is a deficit of knowledge and skills considering this special task, the aim of the current pilot study was to develop a canine muscle cell culture system derived from muscle biopsies of healthy client-owned dogs, which allows sampling of the biopsies under working conditions in the daily veterinary practise. Results Muscular biopsies from 16 dogs of different age and breed were taken during standard surgical procedures and were stored for one to three days at 4°C in a transport medium in order to simulate shipping conditions. Afterwards biopsies were professionally processed, including harvesting of satellite cells, inducing their proliferation, differentiating them into myotubes and recultivating myotubes after long-term storage in liquid nitrogen. Myogenic origin of cultured cells was determined by immunofluorescence, immunohistology and by their typical morphology after inducing differentiation. Subsequent to the differentiation into myotubes feasibility of patch-clamp recordings of voltage gated ion channels was successfully. Conclusion We have developed a canine muscle cell culture system, which allows sampling of biopsies from young and old dogs of different breeds under practical conditions. Patch clamp measurements can be carried out with the cultured myotubes demonstrating potential of these cells as source for functional research.

  20. Admittance Spectroscopy in CZTSSe: Metastability Behavior and Voltage Dependent Defect Study

    Energy Technology Data Exchange (ETDEWEB)

    Koeper, Mark J.; Hages, Charles J.; Li, Jian V.; Levi, Dean; Agrawal, Rakesh

    2016-11-21

    Admittance spectroscopy has been performed on a CZTSSe device with a carrier injection pretreatment and under electronically relaxed conditions to demonstrate metastability behavior. We show that the measurements with the carrier injection pretreatment demonstrate two admittance signatures while the relaxed measurement demonstrates only one admittance signature with a different activation energy. Additionally, voltage dependent admittance spectroscopy was performed using the carrier injection pretreatment method at each of the applied voltage bias. The activation energies of the two admittance signatures were calculated and are shown to be independent of the voltage bias.

  1. Simple Switching Strategy for High-Torque Control Performance utilizing Neutral Point Clamped Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    Nor Faezah Alias

    2013-12-01

    Full Text Available Three-level Neutral Point Clamped (NPC inverter allows the configuration of switching devices to operate at high voltage and produce lower current/voltage harmonics. It is known that, DTC of induction machine which employs hysteresis controller has major drawbacks namely larger torque ripple and variable switching frequency. This paper aims to propose a suitable voltage vector selection to provide better torque regulation and lower switching frequency by employing DTC with 3-level NPC multilevel inverter. A simple switching strategy was formulated using 7-level torque hysteresis and 2-level flux hysteresis controllers to give more options in selecting an appropriate voltage vector, inherently, according the motor operation conditions. The improvements offered were verified through simulations.

  2. Characterization of ryanodine receptor type 1 single channel activity using "on-nucleus" patch clamp.

    Science.gov (United States)

    Wagner, Larry E; Groom, Linda A; Dirksen, Robert T; Yule, David I

    2014-08-01

    In this study, we provide the first description of the biophysical and pharmacological properties of ryanodine receptor type 1 (RyR1) expressed in a native membrane using the on-nucleus configuration of the patch clamp technique. A stable cell line expressing rabbit RyR1 was established (HEK-RyR1) using the FLP-in 293 cell system. In contrast to untransfected cells, RyR1 expression was readily demonstrated by immunoblotting and immunocytochemistry in HEK-RyR1 cells. In addition, the RyR1 agonists 4-CMC and caffeine activated Ca(2+) release that was inhibited by high concentrations of ryanodine. On nucleus patch clamp was performed in nuclei prepared from HEK-RyR1 cells. Raising the [Ca(2+)] in the patch pipette resulted in the appearance of a large conductance cation channel with well resolved kinetics and the absence of prominent subconductance states. Current versus voltage relationships were ohmic and revealed a chord conductance of ∼750pS or 450pS in symmetrical 250mM KCl or CsCl, respectively. The channel activity was markedly enhanced by caffeine and exposure to ryanodine resulted in the appearance of a subconductance state with a conductance ∼40% of the full channel opening with a Po near unity. In total, these properties are entirely consistent with RyR1 channel activity. Exposure of RyR1 channels to cyclic ADP ribose (cADPr), nicotinic acid adenine dinucleotide phosphate (NAADP) or dantrolene did not alter the single channel activity stimulated by Ca(2+), and thus, it is unlikely these molecules directly modulate RyR1 channel activity. In summary, we describe an experimental platform to monitor the single channel properties of RyR channels. We envision that this system will be influential in characterizing disease-associated RyR mutations and the molecular determinants of RyR channel modulation.

  3. EFFECTS OF ELECTROMAGNETIC FIELDS ON HEMATOPOISIS SYSTEM: STUDY ON WORKERS AT HIGH- VOLTAGE SUBSTATIONS

    Directory of Open Access Journals (Sweden)

    H.A YOUSEFI

    2001-06-01

    Full Text Available Introduction: The goal of this study was to evaluate the relationship between occupational exposure to extremely low frequency (ELF electromagnetic fields and risk of Hematological changes among workers at High- voltage substations. This is a case - control study. In the present study 79 worker exposed to electromagetic fields (EMFs were compared to 50 control subjects who were not occupationaly exposed to EMFs. Methods: To measurement the levels of exposure to Lf electric and magnetic fields the strength of electric and magnetic field was determined by Dosimetric method. Worker"s blood samples were collected and analyzed for identification of leukemia and other abnormalities. Questionnaire and physical examination were used to study the effects of ELF fields on worker"s health. Measurements showed a high strength of ELF fields at the work places i.e. Results: Mean value of RBC and Hematocrit decreased significantly among exposed workers compared to controls (P < 0.05, but MCV, MCH and MCHC increased. The value of Neutrophiles increased but Lymphocytes decreased significantly among workers considering their workhistory (P < 0.05. Discussion: Moreover, tow leukemics (ALL, AML and ten hypocromic anemias were found. In conclusion study groups are similar in personal characteristics, the difference in RBC, MCV, MCH has to attributed to ELF fields.

  4. Prolonged penile strangulation with metal clamps

    Institute of Scientific and Technical Information of China (English)

    Chirag Patel; Richard Kim; Michael Delterzo; Run Wang

    2006-01-01

    Various different objects have been reported to strangulate the penis. We reported on a patient who used metal radiator clamps for an extended period of time. Workup included history, physical examination and urinalysis. The patient was taken to the operating room for further evaluation with cystourethroscopy and orthopedic wire cutters were used to break the metal bands.

  5. 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...

  6. 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.

  7. Blood gas values in clamped and unclamped umbilical cord at birth.

    Science.gov (United States)

    Di Tommaso, Mariarosaria; Seravalli, Viola; Martini, Irene; La Torre, Pasquale; Dani, Carlo

    2014-09-01

    To determine the reliability of the cord blood gas analysis on the unclamped cord compared to the standard technique of sampling on double clamped cord. Prospective observational study conducted on 46 singleton neonates vaginally delivered at term. Matched pairs of umbilical artery and vein blood samples were collected from unclamped cord within 90s after birth and from the same cord after clamping, with the clamping occurring immediately after the first blood collection. A blood gas analysis was performed on each collected sample. Arterial and venous blood samples were analyzed for pH, PO2, pCO2, SaO2, hemoglobin concentration (ctHb) and base excess (BE). The values were compared between the two groups (clamped vs unclamped) using a Wilcoxon test. No significant difference was found in pH, PO2, pCO2, SaO2 and ctHb values on arterial blood between unclamped and clamped cord. The only significant difference was related to BE (pblood, the values of pH, PO2, pCO2 were comparable between unclamped and clamped cord, while the values of SaO2, ctHb and BE were significantly different (pblood gas parameters and in the main venous blood gas parameters between unclamped and clamped cord. Sampling of cord blood for gas analysis may be performed on the unclamped cord right after birth without reducing the accuracy of the analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Challenge of Primary Voltage Control in Large Scale Wind Integrated Power System: A Danish Power System Case Study

    DEFF Research Database (Denmark)

    Rather, Zakir Hussain; Chen, Zhe; Thøgersen, Paul

    2013-01-01

    Grid integration of Renewable Energy (RE) at large scale poses vast majority of challenges to secure and stable operation of Power System. This paper presents the challenge of short circuit power and primary voltage control of wind integrated power system where majority of conventional generators...... are replaced by wind generators. The impact of large scale wind integration on fast reactive power support is studied in this paper. Considering both technical and economic aspects, alternatives to address the challenge of dynamic voltage support have also been demonstrated in this paper. A case study...

  9. Characterization of potassium channel modulators with QPatch automated patch-clamp technology: system characteristics and performance

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Friis, Søren; Asmild, Margit

    2003-01-01

    Planar silicon chips with 1-2-microm etched holes (average resistance: 2.04 +/- 0.02 MOmega in physiological buffer, n = 274) have been developed for patch-clamp recordings of whole-cell currents from cells in suspension. An automated 16-channel parallel screening system, QPatch 16, has been...... developed using this technology. A single-channel prototype of the QPatch system was used for validation of the patch-clamp chip technology. We present here data on the quality of patch-clamp recordings and from actual drug screening studies of human potassium channels expressed in cultured cell lines...

  10. Timing of umbilical cord clamping and neonatal haematological status.

    Science.gov (United States)

    Jaleel, Riffat; Deeba, Farah; Khan, Ayesha

    2009-07-01

    To determine the effect of delayed umbilical cord clamping on Hb (haemoglobin) and bilirubin levels of neonates and to identify newborn babies with anaemia and refer them for treatment. This Randomized Controlled Trial was conducted in the Department of Obstetrics and Gynaecology, Unit V, Dow Medical College and Lyari General Hospital and Department of Pathology, Lyari General Hospital, between 1st November, 2006 and 15th July, 2007. Patients admitted to labour ward were selected according to inclusion criteria of the study. They were randomly allocated to 2 groups. Group A included women in whom umbilical cord was clamped immediately after birth. In Group B, clamping was delayed until cessation of pulsations in the cord. After cutting the cord, sample of blood was collected from the cut end of cord of the newborn for Hb and bilirubin. After 6 hours of birth, another sample of blood was drawn from antecubital vein for serum bilirubin. Samples were sent to laboratory for analysis. All data were entered and analyzed using SPSS version 11. Two hundred women were studied, 100 in each of the 2 groups. Mean maternal Hb was 9.75 g/dl in Group A and 9.95 g/dl in Group B. The average neonatal Hb was 14.1 g/dl in Group A and 15.2 g/dl in Group B (p = 0.008). In all 49% neonates in Group A and 37% in Group B had Hb umbilical cord clamping at birth seems to be safe and can be expected to reduce the prevalence of anaemic newborn babies in our community.

  11. Study on Optimization Strategy for Voltage and Reactive Power Control of Wind Farm

    Science.gov (United States)

    Lu, Q.; Shi, L.; Chen, N.

    A method for calculating reactive power limit of wind farm comprised of doubly-fed induction generators (DFIG) is proposed. The reactive power limit of wind farm is the sum of reactive power limit of DFIGs which is calculated by the method considering static stability margin. Based on this, reactive power control of wind farm is discussed and proposed. The proposed reactive power control is divided into different control modes according to power factor of high voltage side in wind farm substation and voltage of low voltage side in point of interconnection(POI). In different control modes, different control objects are applied on reactive power regulation. After reactive power regulation is finished, some reactive power of wind farm should be released. At last, numerical test system is established, the result shows that the proposed method is effective to support voltage of POI

  12. A Study on the Innovation Cost and Effectiveness Evaluation of Compensation Devices for Voltage Sags

    Science.gov (United States)

    Lang, Xuhui; Hara, Ryoichi; Kita, Hiroyuki; Tanaka, Eiichi; Hasegawa, Jun; Kubo, Hiroshi; Yonaga, Shigeru

    Due to the advancement of information technology and widespread use of power electronic devices in recent years, many customers in various fields have suffered from the voltage sag problem. In order to compensate voltage sags, sensitive loads have been primarily equipped with uninterruptible power supplies (UPS) by each consumer individually. Because consumers have many individual needs, this topic becomes an important problem to be considered by quality consultants in the electric utility industry. Based on this situation, we present the applications of UPS and dynamic voltage restorer (DVR) as compensation devices of voltage sags. By considering the need for power quality, we examine the cost-efficiency of both devices quantitatively. Simulations are carried out and the results are shown in this paper.

  13. Deployment of low-voltage regulator considering existing voltage control in medium-voltage distribution systems

    Directory of Open Access Journals (Sweden)

    Hiroshi Kikusato

    2016-01-01

    Full Text Available Many photovoltaic (PV systems have been installed in distribution systems. This installation complicates the maintenance of all voltages within the appropriate range in all low-voltage distribution systems (LVDSs because the trends in voltage fluctuation differ in each LVDS. The installation of a low-voltage regulator (LVR that can accordingly control the voltage in each LVDS has been studied as a solution to this problem. Voltage control in a medium-voltage distribution system must be considered to study the deployment of LVRs. In this study, we installed LVRs in the LVDSs in which the existing voltage-control scheme cannot prevent voltage deviation and performed a numerical simulation by using a distribution system model with PV to evaluate the deployment of the LVRs.

  14. The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

    Directory of Open Access Journals (Sweden)

    Yunlu Pan

    2014-07-01

    Full Text Available The drag of fluid flow at the solid–liquid interface in the micro/nanoscale is an important issue in micro/nanofluidic systems. Drag depends on the surface wetting, nanobubbles, surface charge and boundary slip. Some researchers have focused on the relationship between these interface properties. In this review, the influence of an applied voltage on the surface wettability, nanobubbles, surface charge density and slip length are discussed. The contact angle (CA and contact angle hysteresis (CAH of a droplet of deionized (DI water on a hydrophobic polystyrene (PS surface were measured with applied direct current (DC and alternating current (AC voltages. The nanobubbles in DI water and three kinds of saline solution on a PS surface were imaged when a voltage was applied. The influence of the surface charge density on the nanobubbles was analyzed. Then the slip length and the electrostatic force on the probe were measured on an octadecyltrichlorosilane (OTS surface with applied voltage. The influence of the surface charge on the boundary slip and drag of fluid flow has been discussed. Finally, the influence of the applied voltage on the surface wetting, nanobubbles, surface charge, boundary slip and the drag of liquid flow are summarized. With a smaller surface charge density which could be achieved by applying a voltage on the surface, larger and fewer nanobubbles, a larger slip length and a smaller drag of liquid flow could be found.

  15. Experimental Study of Electromagnetic Environment in the Vicinity of High Voltage Lines

    Directory of Open Access Journals (Sweden)

    Wafa Tourab

    2011-01-01

    Full Text Available Problem statement: Several studies have investigated the impact of electromagnetic field generated by high voltage power lines on environment. The evaluation of electric and magnetic field quantities are of paramount interest in the characterization of electromagnetic environment of the proposed line. The purpose of this study was to analyze the behavior of electromagnetic fields generated by power lines in an area of strong population. Approach: The method applied in this study was gradual; examined the effects of different couplings between the different neighboring lines on behavior of electric and magnetic fields. Later, these lines will be used as a source of disturbance applied to the auditory implants EMC. Results: The implications of experimental results were also compared and discussed with new standard. Conclusion: The maximum intensities of electric and magnetic fields measured for the circuit of three lines close to each other, within the El-HADJAR substation were significantly lower than the ICNIRP reference levels for occupational and no occupational exposures.

  16. Electrosurgical bipolar vessel sealing versus conventional clamping and suturing for total abdominal hysterectomy: a randomized trial.

    NARCIS (Netherlands)

    Lakeman, M.; Kruitwagen, R.F.P.M.; Vos, M.C.; Roovers, J.P.

    2008-01-01

    STUDY OBJECTIVE: To compare the effects of bipolar vessel sealing versus conventional clamping and suturing in women undergoing total abdominal hysterectomy. DESIGN: A randomized controlled trial was performed. Patients were randomized to vessel sealing or conventional surgery. Postoperative pain wa

  17. Dynamics and Stability of Pinned-Clamped and Clamped-Pinned Cylindrical Shells Conveying Fluid

    Science.gov (United States)

    Misra, A. K.; Wong, S. S. T.; Païdoussis, M. P.

    2001-11-01

    The paper examines the dynamics and stability of fluid-conveying cylindrical shells having pinned-clamped or clamped-pinned boundary conditions, where ``pinned'' is an abbreviation for ``simply supported''. Flügge's equations are used to describe the shell motion, while the fluid-dynamic perturbation pressure is obtained utilizing the linearized potential flow theory. The solution is obtained using two methods - the travelling wave method and the Fourier-transform approach. The results obtained by both methods suggest that the negative damping of the clamped-pinned systems and positive damping of the pinned-clamped systems, observed by previous investigators for any arbitrarily small flow velocity, are simply numerical artefacts; this is reinforced by energy considerations, in which the work done by the fluid on the shell is shown to be zero. Hence, it is concluded that both systems are conservative.

  18. Design and fabrication of a planar patch-clamp substrate using a silicon-on-insulator wafer

    Science.gov (United States)

    Zhenlong, Zhang; Xiangyang, Liu; Yanli, Mao

    2009-09-01

    The planar patch-clamp technique has been applied to high throughput screening in drug discovery. The key feature of this technique is the fabrication of a planar patch-clamp substrate using appropriate materials. In this study, a planar patch-clamp substrate was designed and fabricated using a silicon-on-insulator (SOI) wafer. The access resistance and capacitance of SOI-based planar patch-clamp substrates are smaller than those of bulk silicon-based planar substrates, which will reduce the distributed RC noise.

  19. POLYCYTHEMIA RISK IN NEONATES WITH DELAYED CORD CLAMPING

    Directory of Open Access Journals (Sweden)

    I Gusti Agung Ayu Sri Wulandari Pramana

    2013-07-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE Delayed Cord Clamping is still a controversial issue in the world of medicine. Until recently, the perfect times to do a Delayed Cord Clamping in various parts of the Earth in the world are still very diverse. There are a few things that became a major concern associated with Delayed Cord Clamping, one of which is the increase in blood volume due to an increase in the number of erythrocytes which led to occurrence of neonatal polycythemia which later can lead to various complications. Polycythemia in neonates is a situation where the value of venous blood hematokrit over 65% (0.65 or the amount of hemoglobin more than 22gr/Dl. However, to date the data from a variety of the latest research and analysis of the studies mention that the polycythemia that occurs in neonates with umbilical cord pinching the flush delay was mild polycythemia that can improve after 48 to 72 hours after the baby is born.

  20. Cleaning patch-clamp pipettes for immediate reuse

    Science.gov (United States)

    Kolb, I.; Stoy, W. A.; Rousseau, E. B.; Moody, O. A.; Jenkins, A.; Forest, C. R.

    2016-01-01

    Patch-clamp recording has enabled single-cell electrical, morphological and genetic studies at unparalleled resolution. Yet it remains a laborious and low-throughput technique, making it largely impractical for large-scale measurements such as cell type and connectivity characterization of neurons in the brain. Specifically, the technique is critically limited by the ubiquitous practice of manually replacing patch-clamp pipettes after each recording. To circumvent this limitation, we developed a simple, fast, and automated method for cleaning glass pipette electrodes that enables their reuse within one minute. By immersing pipette tips into Alconox, a commercially-available detergent, followed by rinsing, we were able to reuse pipettes 10 times with no degradation in signal fidelity, in experimental preparations ranging from human embryonic kidney cells to neurons in culture, slices, and in vivo. Undetectable trace amounts of Alconox remaining in the pipette after cleaning did not affect ion channel pharmacology. We demonstrate the utility of pipette cleaning by developing the first robot to perform sequential patch-clamp recordings in cell culture and in vivo without a human operator. PMID:27725751

  1. Voltage-controlled magnetic anisotropy in Fe|MgO tunnel junctions studied by x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miwa, Shinji, E-mail: miwa@mp.es.osaka-u.ac.jp; Matsuda, Kensho; Tanaka, Kazuhito; Goto, Minori; Suzuki, Yoshishige [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Kotani, Yoshinori; Nakamura, Tetsuya [Japan Synchrotron Radiation Research Institute/SPring-8, Sayo, Hyogo 679-5198 (Japan)

    2015-10-19

    In this study, voltage-controlled magnetic anisotropy (VCMA) in Fe|MgO tunnel junctions was investigated via the magneto-optical Kerr effect, soft x-ray absorption spectroscopy, and magnetic circular dichroism spectroscopy. The Fe|MgO tunnel junctions showed enhanced perpendicular magnetic anisotropy under external negative voltage, which induced charge depletion at the Fe|MgO interface. Despite the application of voltages of opposite polarity, no trace of chemical reaction such as a redox reaction attributed to O{sup 2−} migration was detected in the x-ray absorption spectra of the Fe. The VCMA reported in the Fe|MgO-based magnetic tunnel junctions must therefore originate from phenomena associated with the purely electric effect, that is, surface electron doping and/or redistribution induced by an external electric field.

  2. Reducing crosstalk in array structures by controlling the excitation voltage of individual elements: a feasibility study.

    Science.gov (United States)

    Bybi, A; Grondel, S; Assaad, J; Hladky-Hennion, A-C; Granger, C; Rguiti, M

    2013-08-01

    This paper describes a procedure to minimize crosstalk between the individual elements of a piezoelectric transducer array. A two-dimensional finite elements model was developed and the excitation voltages predicted by the model were applied to the array prototypes made of PZT 27 ceramic. Symmetric and asymmetric linear phased arrays operating at approximately 450 kHz were tested in the feasibility study. The studies were carried out at low frequency to facilitate the fabrication of the transducer arrays and to check the feasibility in this case. The novelty of our approach is to offer active cancellation of crosstalk in transducer arrays generating continuous waves, even in the presence of fabrication defects. The experimental results showed the validity of the approach and demonstrated that crosstalk can be reduced by about 6-10 dB. In ultrasonic imaging systems, this method could be introduced by using a multichannel generator providing electrical signals containing both phased signals required to focalize and deflect the acoustic beam associated with the correction signals.

  3. The high voltage system of the RICH and the multiplicity study with LHCb data

    CERN Document Server

    Fanchini, E; Pessina, G; Gys, T

    2011-01-01

    This thesis is about the work done during my PhD at the Univerità degli studi di Milano–Bicocca. During these three years I was involved in the RICH group of the LHCb experiment. LHCb is one of the four main experiments at CERN. It uses proton–proton collisions to study CP violation and to search for new physics beyond the Standard Model in the $b$ decays. One of the main feature of the experiment is the particle identification, performed with the Ring Imaging Cherenkov (RICH) technology. The RICH detects Cherenkov rings via photons emitted by charged particles traversing radiator materials. The photon detection system used consists of pixel Hybrid Photon Detectors (HPDs). They convert photons into photoelectrons which are then accelerated by means of a field generated by three electrodes, biased with high voltages (-18 kV, -17.7 kV and -14.8 kV), onto the silicon pixel anode. The energy released in the pixel is converted into a binary output. My work can be divided in two main parts: the hardware and th...

  4. Modelling and Simulation of the SVC for Power System Flow Studies: Electrical Network in voltage drop

    Directory of Open Access Journals (Sweden)

    Narimen Aouzellag LAHAÇANI

    2008-12-01

    Full Text Available The goal of any Flexible AC Transmission Systems (FACTS devices study is to measure their impact on the state of the electrical networks into which they are introduced. Their principal function is to improve the static and dynamic properties of the electrical networks and that by increasing the margins of static and dynamic stability and to allow the power transit to the thermal limits of the lines.To study this impact, it is necessary to establish the state of the network (bus voltages and angles, powers injected and forwarded in the lines before and after the introduction of FACTS devices. This brings to calculate the powers transit by using an iterative method such as Newton-Raphson. Undertaking a calculation without the introduction of FACTS devices followed by a calculation with the modifications induced by the integration of FACTS devices into the network, makes it possible to compare the results obtained in both cases and thus assess the interest of the use of devices FACTS.

  5. Surges in low voltage distribution networks: some of conducted studies; Surtos em redes de baixa tensao: alguns estudos realizados

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-04-01

    This article presents an experience conducted by the Brazilian CELESC - Centrais Electricas de Santa Catarina, by installing two low voltage Si C lightning rods, one near of a batch of distribution transformers, and the other in the protection and measurement cabinet. That installation considered the high number of damages in transformers and meters in a region where 118 days of storm are detected. For the study, two regions presented similar climate characteristics and high number of damaged equipment. The low voltage lightning rods were installed only in one of the regions.

  6. Can robots patch-clamp as well as humans? Characterization of a novel sodium channel mutation.

    Science.gov (United States)

    Estacion, M; Choi, J S; Eastman, E M; Lin, Z; Li, Y; Tyrrell, L; Yang, Y; Dib-Hajj, S D; Waxman, S G

    2010-06-01

    Ion channel missense mutations cause disorders of excitability by changing channel biophysical properties. As an increasing number of new naturally occurring mutations have been identified, and the number of other mutations produced by molecular approaches such as in situ mutagenesis has increased, the need for functional analysis by patch-clamp has become rate limiting. Here we compare a patch-clamp robot using planar-chip technology with human patch-clamp in a functional assessment of a previously undescribed Nav1.7 sodium channel mutation, S211P, which causes erythromelalgia. This robotic patch-clamp device can increase throughput (the number of cells analysed per day) by 3- to 10-fold. Both modes of analysis show that the mutation hyperpolarizes activation voltage dependence (8 mV by manual profiling, 11 mV by robotic profiling), alters steady-state fast inactivation so that it requires an additional Boltzmann function for a second fraction of total current (approximately 20% manual, approximately 40% robotic), and enhances slow inactivation (hyperpolarizing shift--15 mV by human,--13 mV robotic). Manual patch-clamping demonstrated slower deactivation and enhanced (approximately 2-fold) ramp response for the mutant channel while robotic recording did not, possibly due to increased temperature and reduced signal-to-noise ratio on the robotic platform. If robotic profiling is used to screen ion channel mutations, we recommend that each measurement or protocol be validated by initial comparison to manual recording. With this caveat, we suggest that, if results are interpreted cautiously, robotic patch-clamp can be used with supervision and subsequent confirmation from human physiologists to facilitate the initial profiling of a variety of electrophysiological parameters of ion channel mutations.

  7. A Modal Analysis Study of Thin Parallelogram Plates Clamped on the Rim with and without Defects Using the SolidWorks Program

    Directory of Open Access Journals (Sweden)

    Marian-Dumitru Nedeloni

    2015-09-01

    Full Text Available This paper presents the study of the modal analysis of four types of plates in parallelogram shape, with or without defects, using the SolidWorks program. The results obtained after this study, have targeted the behavior of plates regarding the mesh, the deformation scale, the resultant amplitude, the rotational speeds, respectively the Eigen frequencies according to the vibration modes.

  8. A High Voltage-lift Efficient Isolated Full Bridge DC-DC Converter

    Directory of Open Access Journals (Sweden)

    A. Gopi

    2014-05-01

    Full Text Available The aim of this study is to propose a high voltage lift isolated full bridge dc-dc converter. The proposed converter consists of an isolation transformer a low turn ratio to obtain high step up voltage gain. The secondary of the transformer connected with two boosting capacitors which connects parallel when power switches switch on period and discharged in series during the switch off period. In addition full bridge converter on primary side consists of clamping diode and capacitor, leakage energy is recycled there by improving conversion efficiency. The proposed circuits simulated using PSIM software form input voltage of 48V, an output of 410 V obtained. These results and operations experimented and validated by implementing in hardware model at 20/40 Vdc, 20 Watts.

  9. A Study on Measurement Error during Alternating Current Induced Voltage Tests on Large Transformers

    Institute of Scientific and Technical Information of China (English)

    WANG Xuan; LI Yun-ge; CAO Xiao-long; LIU Ying

    2006-01-01

    The large transformer is pivotal equipment in an electric power supply system; Its partial discharge test and the induced voltage withstand test on large transformers are carried out at a frequency about twice the working frequency. If the magnetizing inductance cannot compensate for the stray capacitance, the test sample turns into a capacitive load and a capacitive rise exhibits in the testing circuit. For self-restoring insulation, a method has been recommended in IEC60-1 that an unapproved measuring system be calibrated by an approved system at a voltage not less than 50% of the rated testing voltage, and the result then be extrapolated linearly. It has been found that this method leads to great error due to the capacitive rise if it is not correctly used during a withstand voltage test under certain testing conditions, especially for a test on high voltage transformers with large capacity. Since the withstand voltage test is the most important means to examine the operation reliability of a transformer, and it can be destructive to the insulation, a precise measurement must be guaranteed. In this paper a factor, named as the capacitive rise factor, is introduced to assess the rise. The voltage measurement error during the calibration is determined by the parameters of the test sample and the testing facilities, as well as the measuring point. Based on theoretical analysis in this paper, a novel method is suggested and demonstrated to estimate the error by using the capacitive rise factor and other known parameters of the testing circuit.

  10. Voltage-Independent Calcium Release in Heart Muscle

    Science.gov (United States)

    Niggli, Ernst; Lederer, W. Jonathan

    1990-10-01

    The Ca2+ that activates contraction in heart muscle is regulated as in skeletal muscle by processes that depend on voltage and intracellular Ca2+ and involve a positive feedback system. How the initial electrical signal is amplified in heart muscle has remained controversial, however. Analogous protein structures from skeletal muscle and heart muscle have been identified physiologically and sequenced; these include the Ca2+ channel of the sarcolemma and the Ca2+ release channel of the sarcoplasmic reticulum. Although the parallels found in cardiac and skeletal muscles have provoked valuable experiments in both tissues, separation of the effects of voltage and intracellular Ca2+ on sarcoplasmic reticulum Ca2+ release in heart muscle has been imperfect. With the use of caged Ca2+ and flash photolysis in voltage-clamped heart myocytes, effects of membrane potential in heart muscle cells on Ca2+ release from intracellular stores have been studied. Unlike the response in skeletal muscle, voltage across the sarcolemma of heart muscle does not affect the release of Ca2+ from the sarcoplasmic reticulum, suggesting that other regulatory processes are needed to control Ca2+-induced Ca2+ release.

  11. 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.

  12. Study on the influence of applied voltage and feed concentration on the performance of electrodeionization

    Directory of Open Access Journals (Sweden)

    Yohanes Ervan1

    2002-11-01

    Full Text Available Electrodeionization (EDI, a membrane process for removing ion from aqueous feed, becomes more popular nowadays. Its ability to produce ultrapure water gives significant contributions to chemical and semiconductor industries. Only few researches have been published to evaluate its performance in producing ultrapure water, especially in studying and analysing the relation between process parameter and its performance. This work is intended to observe and evaluate the influence of voltage applied and feed concentration on EDI performance. The raw material used in experiment is tap water filtered by reverse osmosis unit before proceeding to the electrodeionization. Product analysis, the diluate as well as the concentrate, is carried out by using conductivity meter and pH meter. The experimental results are presented in i vs V curve, product conductivity vs time, and product pH vs time. From experimental results, it is concluded that concentration polarization can be minimized in EDI process, the increasing of applied current increases product pH. However, there is a limit in gradient concentration between feed and concentrate to minimize the occurence of counter diffusion phenomena.

  13. A dynamic Monte Carlo study of anomalous current voltage behaviour in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Feron, K., E-mail: Krishna.Feron@csiro.au; Fell, C. J. [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia); CSIRO Energy Flagship, Newcastle, NSW 2300 (Australia); Zhou, X.; Belcher, W. J.; Dastoor, P. C. [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia)

    2014-12-07

    We present a dynamic Monte Carlo (DMC) study of s-shaped current-voltage (I-V) behaviour in organic solar cells. This anomalous behaviour causes a substantial decrease in fill factor and thus power conversion efficiency. We show that this s-shaped behaviour is induced by charge traps that are located at the electrode interface rather than in the bulk of the active layer, and that the anomaly becomes more pronounced with increasing trap depth or density. Furthermore, the s-shape anomaly is correlated with interface recombination, but not bulk recombination, thus highlighting the importance of controlling the electrode interface. While thermal annealing is known to remove the s-shape anomaly, the reason has been not clear, since these treatments induce multiple simultaneous changes to the organic solar cell structure. The DMC modelling indicates that it is the removal of aluminium clusters at the electrode, which act as charge traps, that removes the anomalous I-V behaviour. Finally, this work shows that the s-shape becomes less pronounced with increasing electron-hole recombination rate; suggesting that efficient organic photovoltaic material systems are more susceptible to these electrode interface effects.

  14. Experimental and simulation study of a capacitively coupled oxygen discharge driven by tailored voltage waveforms

    Science.gov (United States)

    Derzsi, Aranka; Lafleur, Trevor; Booth, Jean-Paul; Korolov, Ihor; Donkó, Zoltán

    2016-02-01

    We report experimental and particle-based kinetic simulation studies of low-pressure capacitively coupled oxygen plasmas driven by tailored voltage waveforms that consist of up to four harmonics of base frequency 13.56 MHz. Experimentally determined values of DC self-bias and electrical power deposition, as well as flux density and flux-energy distribution of the positive ions at the grounded electrode are compared with simulation data for a wide range of operating conditions. Very good agreement is found for self-bias and flux-energy distribution of the positive ions at the electrodes, while a fair agreement is reached for discharge power and ion flux data. The simulated spatial and temporal behaviour of the electric field, electron density, electron power absorption, ionization rate and mean electron energy shows a transition between sheath expansion heating and drift-ambipolar discharge modes, induced by changing either the number of harmonics comprising the excitation waveform or the gas pressure. The simulations indicate that under our experimental conditions the plasma operates at high electronegativity, and also reveal the crucial role of {{\\text{O}}2}≤ft({{a}1}{{Δ }g}\\right) singlet metastable molecules in establishing discharge behavior via the fast destruction of negative ions within the bulk plasma.

  15. Simulation and Experimental Study of Arc Column Expansion After Ignition in Low-Voltage Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    MA Qiang; RONG Mingzhe; WU Yi; XU Tiejun; SUN Zhiqiang

    2008-01-01

    The dynamicprocess of arc pressure and corresponding arc column expansion, which is the main feature after arc ignition and has a significant effect on the breaking behaviour of low -voltage circuit breakers, is studied. By constructing a three dimensional mathematical model of air arc plasma and adopting the Control Volume Method, the parameters of arc plasma including temperature and pressure axe obtained. The variations of pressure field and temperature field with time are simulated. The result indicates that there are six stages for the process of arc column expansion according to the variation of pressure in arc chamber. In the first stage, the maximal pressure locates in the region close to cathode, and in the second stage the maximal pressure shifts to the region close to the anode. In the third stage, the pressure difference between the middle of arc column and the ambient gas is very large, so the arc column begins to expand apparently. In the fourth stage, the pressure wave propagates towards both ends and the maximal pressure appears at the two ends when the pressure wave reaches both sidewalls. In the fifth stage, the pressure wave is reflected and collides in the middle of the arc chamber. In the last stage, the propagation and reflection of pressure wave will repeat several times until a steady burning state is reached. In addition, the experimental results of arc column expansion, corresponding to the arc pressure variation, are presented to verify the simulation results.

  16. 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.

  17. Towards a Dynamic Clamp for Neurochemical Modalities

    Directory of Open Access Journals (Sweden)

    Catalina Maria Rivera

    2015-05-01

    Full Text Available The classic dynamic clamp technique uses a real-time electrical interface between living cells and neural simulations in order to investigate hypotheses about neural function and structure. One of the acknowledged drawbacks of that technique is the limited control of the cells’ chemical microenvironment. In this manuscript, we use a novel combination of nanosensor and microfluidic technology and microfluidic and neural simulations to add sensing and control of chemical concentrations to the dynamic clamp technique. Specifically, we use a microfluidic lab-on-a-chip to generate distinct chemical concentration gradients (ions or neuromodulators, to register the concentrations with embedded nanosensors and use the processed signals as an input to simulations of a neural cell. The ultimate goal of this project is to close the loop and provide sensor signals to the microfluidic lab-on-a-chip to mimic the interaction of the simulated cell with other cells in its chemical environment.

  18. Mechanical and metallurgical properties of carotid artery clamps.

    Science.gov (United States)

    Dujovny, M; Kossovsky, N; Kossowsky, R; Segal, R; Diaz, F G; Kaufman, H; Perlin, A; Cook, E E

    1985-11-01

    The mechanical and metallurgical properties of carotid artery clamps were evaluated. The pressure plate retreat propensity, metallurgical composition, surface morphology, magnetic properties, and corrosion resistance of the Crutchfield, Selverstone, Salibi, and Kindt clamps were tested. None of the clamps showed evidence of pressure plate retreat. The clamps differed significantly in their composition, surface cleanliness, magnetic properties, and corrosion resistance. The Crutchfield clamp was the only one manufactured from an ASTM-ANSI-approved implantable stainless steel (AISI 316) and the only clamp in which the surfaces were clean and free of debris. The Selverstone clamp was made principally from AISI 304 stainless steel, as was one Salibi clamp. The pressure plate on another Salibi clamp was made from a 1% chromium and 1% manganese steel. Machining and surface debris consisting principally of aluminum, silicon, and sulfur was abundant on the Selverstone and Salibi clamps. The Kindt clamp was manufactured from AISI 301 stainless steel with a silicate-aluminized outer coating. The Crutchfield and Selverstone clamps were essentially nonferromagnetic, whereas the Salibi and Kindt clamps were sensitive to magnetic flux. In the pitting potential corrosion test, the Crutchfield clamp demonstrated good corrosion resistance with a pitting potential of 310 mV and no surface corrosion or pitting by scanning electron microscopy examination. The Selverstone clamp had lower pitting potentials and showed various degrees of corrosion and surface pitting by scanning electron microscopy. The Salibi pressure plate had a very low pitting potential of -525 mV and showed severe corrosion. By metallurgical criteria, only the Crutchfield clamp is suitable for long term implantation.

  19. 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....

  20. AN ACTIVE VALVE WITH A CLAMPED MEMBRANE

    DEFF Research Database (Denmark)

    2009-01-01

    An active valve for use e.g. in fluidic microsystems is provided, wherein the active valve comprises a membrane having at least one flow gate, arranged between a first and a second substantially rigid element. Adjusting means provides an adjustment of the clamping force on membrane arranged between...... the first and second substantially rigid element. Hereby the flow rate through the active valve can be continuously and precisely controlled....

  1. Multilevel-clamped multilevel converters (MLC2)

    DEFF Research Database (Denmark)

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

    2012-01-01

    This letter introduces a new series of multilevel (ML) converters based on the ML clamping concept. By applying this technique, a ML clamping unit (MCU) conveys additional levels for synthesizing the output waveforms of a diode-clampedML dc– ac power converter. The basic building block of the ML ...

  2. 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 Section 882.4460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... holder (skull clamp). (a) Identification. A neurosurgical head holder (skull clamp) is a device used...

  3. Effects of Delayed Umbilical Cord Clamping vs Early Clamping on Anemia in Infants at 8 and 12 Months: A Randomized Clinical Trial.

    Science.gov (United States)

    Kc, Ashish; Rana, Nisha; Målqvist, Mats; Jarawka Ranneberg, Linda; Subedi, Kalpana; Andersson, Ola

    2017-03-01

    Delayed umbilical cord clamping has been shown to improve iron stores in infants to 6 months of age. However, delayed cord clamping has not been shown to prevent iron deficiency or anemia after 6 months of age. To investigate the effects of delayed umbilical cord clamping, compared with early clamping, on hemoglobin and ferritin levels at 8 and 12 months of age in infants at high risk for iron deficiency anemia. This randomized clinical trial included 540 late preterm and term infants born vaginally at a tertiary hospital in Kathmandu, Nepal, from October 2 to November 21, 2014. Follow-up included blood levels of hemoglobin and ferritin at 8 and 12 months of age. Follow-up was completed on December 11, 2015. Analysis was based on intention to treat. Infants were randomized to delayed umbilical cord clamping (≥180 seconds after delivery) or early clamping (≤60 seconds after delivery). Main outcomes included hemoglobin and anemia levels at 8 months of age with the power estimate based on the prevalence of anemia. Secondary outcomes included hemoglobin and anemia levels at 12 months of age and ferritin level, iron deficiency, and iron deficiency anemia at 8 and 12 months of age. In this study of 540 infants (281 boys [52.0%] and 259 girls [48.0%]; mean [SD] gestational age, 39.2 [1.1] weeks), 270 each were randomized to the delayed and early clamping groups. At 8 months of age, 212 infants (78.5%) from the delayed group and 188 (69.6%) from the early clamping group returned for blood sampling. After multiple imputation analysis, infants undergoing delayed clamping had higher levels of hemoglobin (10.4 vs 10.2 g/dL; difference, 0.2 g/dL; 95% CI, 0.1 to 0.4 g/dL). Delayed cord clamping also reduced the prevalence of anemia (hemoglobin level clamping group in 60 (22.2%) vs 103 (38.1%) patients (relative risk, 0.58; 95% CI, 0.44-0.77; NNT, 6; 95% CI, 4-13). At 12 months, delayed cord clamping still resulted in a hemoglobin level of 0.3 (95% CI, 0.04-0.5) g/dL higher

  4. The Mechanism of Voltage Dependent Gating of the NaChBac Prokaryotic Sodium Channel

    Science.gov (United States)

    Decaen, Paul G.

    Electrical signaling in cells depends on selective conductance of ions through membrane proteins called 'voltage gated ion channels'. These channels are characterized by their ability turn on and off the flow of ionic current by opening and closing their conductive pore in response to changes in membrane potential. The opening and closing of the pore is a mechanically linked to conformational movement of the positively charged fourth transmembrane segment (S4) in 'the voltage sensor' region. How the S4 moves in response to membrane potential is a controversial subject. In this thesis, we used the prokaryotic sodium channel NaChBac as our model sodium channel to study voltage dependent movement of the S4 in the voltage sensor. We use a disulfide-locking method where we introduced pairs of cysteines in the voltage sensor that crosslink and trap the S4 in its path after depolarization. We screened over one hundred mutations of the NaChBac channel in the whole cell patch clamp assay and demonstrated discrete and sequential voltage dependent ion pair interactions that occur in at least three states between the positively charged residues of the S4 segment and the acidic residues in the S1, S2 and S3 segments. In conjunction with structural modeling of the voltage sensor and our disulfide locking data, we propose that the S4 moves in and out of the plane of the membrane 8-13 A, forming distinct gating charge interactions with counter charges of the voltage sensor and adopts a 310 helix over a portion of its structure during activation. These findings are compatible with the sliding helix model and refine our understanding of the structural determinates of voltage sensor function in voltage gated ion channels.

  5. A general modelling and control algorithm of a three-phase multilevel diode clamped inverter by means of a direct space vector control

    Science.gov (United States)

    Bouhali, O.; Francois, B.; Berkouk, E. M.; Saudemont, C.

    2005-07-01

    This paper presents a simple and general direct modulation strategy that enables to copy directly modulated waveforms onto output voltages of a multilevel three-phase Diode Clamped Inverter (DCI). A general modelling of this converter is presented. A space vector scheme is developed without using Park transforms. Based on this algorithm, the location of the reference voltage vector is determined and the voltage vectors for the modulation are deduced. Simultaneously, their durations are calculated. The proposed algorithm is general and can be directly applied to a (n+1) levels inverter independently on its topology (Diode Clamped Inverter, Neutral Point Clamped, Flying Capacitor Inverter...). To verify this algorithm, both control algorithms of a 5-level DCI and a 11-level DCI are considered and simulation results are given.

  6. 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

    2015-04-01

    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.

  7. Voltage holding study of 1 MeV accelerator for ITER neutral beam injector.

    Science.gov (United States)

    Taniguchi, M; Kashiwagi, M; Umeda, N; Dairaku, M; Takemoto, J; Tobari, H; Tsuchida, K; Yamanaka, H; Watanabe, K; Kojima, A; Hanada, M; Sakamoto, K; Inoue, T

    2012-02-01

    Voltage holding test on MeV accelerator indicated that sustainable voltage was a half of that of ideal quasi-Rogowski electrode. It was suggested that the emission of the clumps is enhanced by a local electric field concentration, which leads to discharge initiation at lower voltage. To reduce the electric field concentration in the MeV accelerator, gaps between the grid supports were expanded and curvature radii at the support corners were increased. After the modifications, the accelerator succeeded in sustaining -1 MV in vacuum without beam acceleration. However, the beam energy was still limited at a level of 900 keV with a beam current density of 150 A∕m(2) (346 mA) where the 3 × 5 apertures were used. Measurement of the beam profile revealed that deflection of the H(-) ions was large and a part of the H(-) ions was intercepted at the acceleration grid. This causes high heat load on the grids and the breakdowns during beam acceleration. To suppress the direct interception, new grid system was designed with proper aperture displacement based on a 3D beam trajectory analysis. As the result, the beam deflection was compensated and the voltage holding during the beam acceleration was improved. Beam parameter of the MeV accelerator was increased to 980 keV, 185 A∕m(2) (427 mA), which is close to the requirement of ITER accelerator (1 MeV, 200 A∕m(2)).

  8. Suitability of voltage stability study methods for real-time assessment

    DEFF Research Database (Denmark)

    Perez, Angel; Jóhannsson, Hjörtur; Vancraeyveld, Pieter;

    2013-01-01

    This paper analyzes the suitability of existing methods for long-term voltage stability assessment for real-time operation. An overview of the relevant methods is followed with a comparison that takes into account the accuracy, computational efficiency and characteristics when used for security...

  9. Large Scale Solar Power Integration in Distribution Grids: PV Modelling, Voltage Support and Aggregation Studies

    NARCIS (Netherlands)

    Samadi, A.

    2014-01-01

    Long term supporting schemes for photovoltaic (PV) system installation have led to accommodating large numbers of PV systems within load pockets in distribution grids. High penetrations of PV systems can cause new technical challenges, such as voltage rise due to reverse power flow during light load

  10. VOLTAGE COMPENSATION USING ARTIFICIAL NEURAL NETWORK

    African Journals Online (AJOL)

    VOLTAGE COMPENSATION USING ARTIFICIAL NEURAL NETWORK: A CASE STUDY OF RUMUOLA DISTRIBUTION NETWORK. ... The artificial neural networks controller engaged to controlling the dynamic voltage ... Article Metrics.

  11. Study & Design on the Manual Clamping Mechanism for A New Style of Fast Dropping Device%一种新型速降装置手动夹紧机构的改进设计与分析

    Institute of Scientific and Technical Information of China (English)

    陶表达

    2011-01-01

    The three-steps reinforcement manual clamping devices is designed for specific working condition.Its structure features and working principles are analyzed.The calculating formulas for the clamping force are gave.The best force-increasing angle range is pointed.The notable features of this clamping device are simple structure, light weight and a very large output clamping force.In addition, it is very easy operation and manufacture.%根据特殊工况,设计一种手动三级增力夹紧机构,分析其工作原理和结构特点,给出夹紧力计算公式,并优化增力角,指出最佳角度工作区间.其显著特点是结构简单、重量轻、夹紧力大、操作方便、制造工艺性好.

  12. Analyzing of Dynamic Voltage Restorer in Series Compensation Voltage

    Directory of Open Access Journals (Sweden)

    Naser Parhizgar

    2012-02-01

    Full Text Available The Dynamic Voltage Restorer (DVR is a series-connected compensator to generate a controllable voltage to against the short-term voltage disturbances. The technique of DVR is an effective and cost competitive approach to improve voltage quality at the load side. This study presents a single-phase and threephase DVR system with reduced switch-count topology to protect the sensitive load against abnormal voltage conditions. Most basic function, the DVR configuration consist of a two level Voltage Source Converter (VSC, a dc energy storage device, a coupling transformer Connected in shunt with the ac system This study presents the application of Dynamic Voltage Restorer (DVR on power distribution systems for mitigation of voltage sag at critical loads. DVR is one of the compensating types of custom power devices. The DVR, which is based on forced-commutated Voltage Source Converter (VSC has been proved suitable for the task of compensating voltage sags/swells. Simulation results are presented to illustrate and understand the performances of DVR in supporting load voltages under voltage sags/swells conditions.

  13. 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

  14. Euglycemic clamp insulin sensitivity and longitudinal systolic blood pressure

    DEFF Research Database (Denmark)

    Petrie, John R; Malik, Muhammad Omar; Balkau, Beverley

    2013-01-01

    Insulin resistance may be an independent risk factor for the development of hypertension, but change in blood pressure (BP) over time has not been adequately studied in healthy individuals fully characterized for insulin sensitivity. In the Relationship between Insulin Sensitivity...... 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...

  15. Late umbilical cord clamping, neonatal hematocrit and Apgar scores: a randomized controlled trial.

    Science.gov (United States)

    Salari, Z; Rezapour, M; Khalili, N

    2014-01-01

    Based on current evidence, there is a little agreement on the best timing for after birth umbilical cord clamping. This study was designed to compare the impact of using two different times for cord clamping on hematocrit concentration and Apgar scores of the neonate. Fifty-six healthy full-term vaginally born neonates were allocated to early (10 seconds after delivery) and late (3 minutes after delivery) umbilical cord clamping groups in this randomized clinical trial. We recorded the length of the 3rd stage of labor and Apgar score at 5 minutes. Infant's hematocrit was measured at 2 and 18 hours of age. Neonatal hematocrit differed between the two groups. Late cord clamping group had greater hematocrit at 2 hours (45.5 ± 4 vs. 49.5 ± 4.4, P = 0.0003) and 18 hours (47.7 ± 5.5 vs. 52.9 ± 4.3, P = 0.0002). Apgar scores at 5 minutes (9.3 ± 0.6 vs. 9.4 ± 0.6, p = 0.5) and duration of delivery 3rd stage (10.2 ± 3.7 min vs. 8.9 ± 5 min, P = 0.2) did not differ between early and late cord clamping groups respectively. Late cord clamping leads to a significant increase in the hematocrit of the neonate but it does not have effects on Apgar score and duration of the 3rd stage of labor.

  16. Can selective arterial clamping with fluorescence imaging preserve kidney function during robotic partial nephrectomy?

    Science.gov (United States)

    McClintock, Tyler R; Bjurlin, Marc A; Wysock, James S; Borofsky, Michael S; Marien, Tracy P; Okoro, Chinonyerem; Stifelman, Michael D

    2014-08-01

    To compare renal functional outcomes in robotic partial nephrectomy (RPN) with selective arterial clamping guided by near-infrared fluorescence (NIRF) imaging to a matched cohort of patients who underwent RPN without selective arterial clamping and NIRF imaging. From April 2011 to December 2012, NIRF imaging-enhanced RPN with selective clamping was used in 42 cases. Functional outcomes of successful cases were compared with a cohort of patients, matched by tumor size, preoperative estimated glomerular filtration rate (eGFR), functional kidney status, age, sex, body mass index, and American Society of Anesthesiologists score, who underwent RPN without selective clamping and NIRF imaging. In matched-pair analysis, selective clamping with NIRF was associated with superior kidney function at discharge, as demonstrated by postoperative eGFR (78.2 vs 68.5 mL/min/1.73 m(2); P = .04), absolute reduction of eGFR (-2.5 vs -14.0 mL/min/1.73 m(2); P functional outcomes when compared with RPN without selective arterial clamping and NIRF imaging. With this effect attenuated at later follow-up, randomized prospective studies and long-term assessment of kidney-specific functional outcomes are needed to further assess the benefits of this technology. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Study on using high injection voltage and spiral inflector in the central region of VEC

    Indian Academy of Sciences (India)

    V S Pandit

    2002-12-01

    A feasibility study of using high injection voltage and spiral inflector in the present heavy ion central region of VEC is described. Conditions necessary for waist-to-waist transfer of the ion beam in the hole lens of main magnet have been obtained. The results of orbit studies of a variety of heavy ions indicate that a spiral inflector can be used in the central region.

  18. Timing of umbilical cord clamping of term infants.

    Science.gov (United States)

    Ceriani Cernadas, José María

    2017-04-01

    For at least over 200 years, multiple controversies have arisen around the timing of umbilical cord clamping. In the past decades, early cord clamping (within the first 15 seconds) had markedly prevailed. Only in the 21st century, randomized controlled trials have demonstrated the benefits of delayed cord clamping (at 2-3 minutes). Delayed cord clamping has been practiced in obstetrics based on the recommendations made by scientific societies and in systematic reviews, which have provided solid evidence to support this practice in term infants. This review describes the most relevant factors supporting the use of delayed cord clamping in term infants. It points out the essential role played by physiological mechanisms which, undoubtedly, allow us to understand the benefits of delayed cord clamping and advise us to wait for what nature has established. Other relevant aspects supporting delayed cord clamping are also described here. Sociedad Argentina de Pediatría.

  19. A revised and unified pressure-clamp/relaxation theory for studying plant cell water relations with pressure probes: in-situ determination of cell volume for calculation of volumetric elastic modulus and hydraulic conductivity.

    Science.gov (United States)

    Knipfer, T; Fei, J; Gambetta, G A; Shackel, K A; Matthews, M A

    2014-10-21

    The cell-pressure-probe is a unique tool to study plant water relations in-situ. Inaccuracy in the estimation of cell volume (νo) is the major source of error in the calculation of both cell volumetric elastic modulus (ε) and cell hydraulic conductivity (Lp). Estimates of νo and Lp can be obtained with the pressure-clamp (PC) and pressure-relaxation (PR) methods. In theory, both methods should result in comparable νo and Lp estimates, but this has not been the case. In this study, the existing νo-theories for PC and PR methods were reviewed and clarified. A revised νo-theory was developed that is equally valid for the PC and PR methods. The revised theory was used to determine νo for two extreme scenarios of solute mixing between the experimental cell and sap in the pressure probe microcapillary. Using a fully automated cell-pressure-probe (ACPP) on leaf epidermal cells of Tradescantia virginiana, the validity of the revised theory was tested with experimental data. Calculated νo values from both methods were in the range of optically determined νo (=1.1-5.0nL) for T. virginiana. However, the PC method produced a systematically lower (21%) calculated νo compared to the PR method. Effects of solute mixing could only explain a potential error in calculated νo of cell turgor) of 19%, which is a fundamental parameter in calculating νo. It followed from the revised theory that the ratio of ΔV/ΔP was inversely related to the solute reflection coefficient. This highlighted that treating the experimental cell as an ideal osmometer in both methods is potentially not correct. Effects of non-ideal osmotic behavior by transmembrane solute movement may be minimized in the PR as compared to the PC method.

  20. 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.

  1. Mapping of voltage sensor positions in resting and inactivated mammalian sodium channels by LRET.

    Science.gov (United States)

    Kubota, Tomoya; Durek, Thomas; Dang, Bobo; Finol-Urdaneta, Rocio K; Craik, David J; Kent, Stephen B H; French, Robert J; Bezanilla, Francisco; Correa, Ana M

    2017-03-07

    Voltage-gated sodium channels (Navs) play crucial roles in excitable cells. Although vertebrate Nav function has been extensively studied, the detailed structural basis for voltage-dependent gating mechanisms remain obscure. We have assessed the structural changes of the Nav voltage sensor domain using lanthanide-based resonance energy transfer (LRET) between the rat skeletal muscle voltage-gated sodium channel (Nav1.4) and fluorescently labeled Nav1.4-targeting toxins. We generated donor constructs with genetically encoded lanthanide-binding tags (LBTs) inserted at the extracellular end of the S4 segment of each domain (with a single LBT per construct). Three different Bodipy-labeled, Nav1.4-targeting toxins were synthesized as acceptors: β-scorpion toxin (Ts1)-Bodipy, KIIIA-Bodipy, and GIIIA-Bodipy analogs. Functional Nav-LBT channels expressed in Xenopus oocytes were voltage-clamped, and distinct LRET signals were obtained in the resting and slow inactivated states. Intramolecular distances computed from the LRET signals define a geometrical map of Nav1.4 with the bound toxins, and reveal voltage-dependent structural changes related to channel gating.

  2. Mapping of voltage sensor positions in resting and inactivated mammalian sodium channels by LRET

    Science.gov (United States)

    Kubota, Tomoya; Durek, Thomas; Dang, Bobo; Finol-Urdaneta, Rocio K.; Craik, David J.; Kent, Stephen B. H.; French, Robert J.; Bezanilla, Francisco; Correa, Ana M.

    2017-01-01

    Voltage-gated sodium channels (Navs) play crucial roles in excitable cells. Although vertebrate Nav function has been extensively studied, the detailed structural basis for voltage-dependent gating mechanisms remain obscure. We have assessed the structural changes of the Nav voltage sensor domain using lanthanide-based resonance energy transfer (LRET) between the rat skeletal muscle voltage-gated sodium channel (Nav1.4) and fluorescently labeled Nav1.4-targeting toxins. We generated donor constructs with genetically encoded lanthanide-binding tags (LBTs) inserted at the extracellular end of the S4 segment of each domain (with a single LBT per construct). Three different Bodipy-labeled, Nav1.4-targeting toxins were synthesized as acceptors: β-scorpion toxin (Ts1)-Bodipy, KIIIA-Bodipy, and GIIIA-Bodipy analogs. Functional Nav-LBT channels expressed in Xenopus oocytes were voltage-clamped, and distinct LRET signals were obtained in the resting and slow inactivated states. Intramolecular distances computed from the LRET signals define a geometrical map of Nav1.4 with the bound toxins, and reveal voltage-dependent structural changes related to channel gating. PMID:28202723

  3. Study on model current predictive control method of PV grid- connected inverters systems with voltage sag

    Science.gov (United States)

    Jin, N.; Yang, F.; Shang, S. Y.; Tao, T.; Liu, J. S.

    2016-08-01

    According to the limitations of the LVRT technology of traditional photovoltaic inverter existed, this paper proposes a low voltage ride through (LVRT) control method based on model current predictive control (MCPC). This method can effectively improve the photovoltaic inverter output characteristics and response speed. The MCPC method of photovoltaic grid-connected inverter designed, the sum of the absolute value of the predictive current and the given current error is adopted as the cost function with the model predictive control method. According to the MCPC, the optimal space voltage vector is selected. Photovoltaic inverter has achieved automatically switches of priority active or reactive power control of two control modes according to the different operating states, which effectively improve the inverter capability of LVRT. The simulation and experimental results proves that the proposed method is correct and effective.

  4. Experimental study on high-voltage solar array sustained arc discharge induced by high charging

    Institute of Scientific and Technical Information of China (English)

    LI Kai; XIE ErQing; WANG Li; LIU YanXia; YANG Yang; SUN YanZheng; CUI XinYu; MAI ShengLi

    2007-01-01

    It has been reported that sustained arc discharge induced by electrostatic discharge (ESD) could cause permanent damage to high-power and high-voltage solar array of spacecrafts. The paper focuses on ESD simulating experiments on Si and GaAs samples, and induces sustained arc discharge. The physical mechanism of sustained arc discharge is discussed by comparing the charging/discharging phenomena between Si and GaAs samples. The experiments show that sustained arc discharge can produce a permanent short-circuit channel between solar cell strings through which the solar array's photovoltaic power may flow out sustainedly. The analyses show that sustained arc discharge strongly depends on solar array structure, solar array operating voltage, ESD characteristics and cell materials.

  5. Experimental study on high-voltage solar array sustained arc discharge induced by high charging

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It has been reported that sustained arc discharge induced by electrostatic discharge (ESD) could cause permanent damage to high-power and high-voltage solar array of spacecrafts. The paper focuses on ESD simulating experiments on Si and GaAs samples, and induces sustained arc discharge. The physical mechanism of sustained arc discharge is discussed by comparing the charging/discharging phenomena between Si and GaAs samples. The experiments show that sustained arc discharge can produce a permanent short-circuit channel between solar cell strings through which the solar array’s photovoltaic power may flow out sustainedly. The analyses show that sustained arc discharge strongly depends on solar array structure, solar array operating voltage, ESD characteristics and cell materials.

  6. Comparative Study of Si and SiC MOSFETs for High Voltage Class D Audio Amplifiers

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    Silicon (Si) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) are traditional utilised in class D audio amplifiers. It has been proposed to replace the traditional inefficient electrodynamic transducer with the electrostatic transducer. This imposes new high voltage requirements...... on the MOSFETs of class D amplifiers, and significantly reduces the selection of suitable MOSFETs. As a consequence it is investigated, if Silicon-Carbide (SiC) MOSFETs could represent a valid alternative. The theory of pulse timing errors are revisited for the application of high voltage and capactive loaded...... class D amplifiers. It is shown, that SiC MOSFETs can compete with Si MSOFETs in terms of THD. Validation is done using simulations and a 500 V amplifier driving a 100 nF load. THD+N below 0.3 % is reported...

  7. Voltage-gated potassium currents within the dorsal vagal nucleus: inhibition by BDS toxin.

    Science.gov (United States)

    Dallas, Mark L; Morris, Neil P; Lewis, David I; Deuchars, Susan A; Deuchars, Jim

    2008-01-16

    Voltage-gated potassium (Kv) channels are essential components of neuronal excitability. The Kv3.4 channel protein is widely distributed throughout the central nervous system (CNS), where it can form heteromeric or homomeric Kv3 channels. Electrophysiological studies reported here highlight a functional role for this channel protein within neurons of the dorsal vagal nucleus (DVN). Current clamp experiments revealed that blood depressing substance (BDS) and intracellular dialysis of an anti-Kv3.4 antibody prolonged the action potential duration. In addition, a BDS sensitive, voltage-dependent, slowly inactivating outward current was observed in voltage clamp recordings from DVN neurons. Electrical stimulation of the solitary tract evoked EPSPs and IPSPs in DVN neurons and BDS increased the average amplitude and decreased the paired pulse ratio, consistent with a presynaptic site of action. This presynaptic modulation was action potential dependent as revealed by ongoing synaptic activity. Given the role of the Kv3 proteins in shaping neuronal excitability, these data highlight a role for homomeric Kv3.4 channels in spike timing and neurotransmitter release in low frequency firing neurons of the DVN.

  8. Study of UPFC Optimal Location Considering Loss Reduction and Improvement of Voltage Stability and Power Flow

    Directory of Open Access Journals (Sweden)

    Islam Youcef DJILANI KOBIBI

    2014-02-01

    Full Text Available With the increase in power demand, operation and planning of large interconnected power system are becoming more complex, so power system will become less secure and stable. A new concept of Flexible AC Transmission system (FACTS brought radical changes in the power system operation and control. FACTS controllers narrow the gap between the no controlled and the controlled power system mode of operation, by providing additional degrees of freedom to control power flows and voltages. Unified Power Flow Controller (UPFC is a versatile FACTS device which can independently or simultaneously control the active power, the reactive power, and the bus voltage to which it is connected. The main purpose of this paper is to identify the optimal location of the Unified Power Flow Controller (UPFC in order to minimize active power losses and improve the voltage profiles using the injection model of the (UPFC in Newton-Raphson load flow algorithm, in an IEEE- 14, 30, 57, 118, 300 Bus test systems.

  9. 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.

  10. Firing clamp: A novel method for single-trial estimation of excitatory and inhibitory synaptic neuronal conductances

    Directory of Open Access Journals (Sweden)

    Anton eChizhov

    2014-03-01

    Full Text Available Understanding non-stationary neuronal activity as seen in vivo requires estimation of both excitatory and inhibitory synaptic conductances from a single trial of recording. We propose a new intracellular recording method for this purpose called firing clamp. Synaptic conductances are estimated from the characteristics of artificially evoked probe spikes, namely the spike amplitude and the mean subthreshold potential, which are sensitive to both excitatory and inhibitory synaptic input signals. The probe spikes, timed at a fixed rate, are evoked in the dynamic-clamp mode by injected meander-like current steps, with the step duration depending on neuronal membrane voltage. We test the method with perforated-patch recordings from isolated cells stimulated by external application or synaptic release of transmitter, and validate the method with simulations of a biophysically-detailed neuron model. The results are compared with the conductance estimates based on conventional current-clamp recordings.

  11. 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.

  12. State-of-the-art automated patch clamp devices: Heat activation, action potentials and high throughput in ion channel screening

    Directory of Open Access Journals (Sweden)

    Sonja eStoelzle

    2011-11-01

    Full Text Available Ion channels are essential in a wide range of cellular functions and their malfunction underlies many disease states making them important targets in drug discovery. Diverse automated patch clamp systems with high-throughput capabilities are available for drug screening, but there are limitations in the application range. For example, solution exchange time, temperature control and the availability of the current clamp mode can be limiting factors. However, further development of existing devices and introduction of new systems widen the range of possible experiments and increase throughput. Here we introduce new features and platforms that meet the needs of drug discovery researchers and basic researchers alike.The Patchliner is an automated patch clamp system capable of recording up to 8 cells simultaneously with high success rates. Novel features such as temperature control and recordings in the current clamp mode are described here. Standard cell lines and excitable cells such as stem cell-derived cardiomyocytes have been used in the voltage clamp and current clamp modes with the view to finding new drug candidates and safety testing methods in a more physiologically relevant environment. The SyncroPatch 96, is a screening platform capable of recording from 96 cells in parallel and offers a throughput of 5000 data points per day. Full dose response curves can be acquired from individual cells reducing the cost per data point. The system is an ideal tool for secondary screening efforts and for safety testing on ligand- and voltage-gated ion channels.The Patchliner and SyncroPatch 96 are ideal platforms for drug discovery, ion channel research and safety testing, combining long awaited features such as parallel action potential recordings and temperature control with extensively increased throughput.

  13. 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.

  14. Direct Torque Control for Three-Level Neutral Point Clamped Inverter-Fed Induction Motor Drive

    Directory of Open Access Journals (Sweden)

    M. K. Sahu

    2012-04-01

    Full Text Available Direct torque control (DTC is a control technique in AC drive systems to obtain high performance torque control. The classical DTC drive contains a pair of hysteresis comparators and suffers from variable switching frequency and high torque ripple. These problems can be solved by using space vector depending on the reference torque and flux. In this paper the space vector modulation technique is applied to the three-level Neutral Point Clamped (NPC inverter control in the proposed DTC-based induction motor drive system, resulting to a significant reduce of torque ripple. Three-level neutral point clamped inverters have been widely used in medium voltage applications. This type of inverters have several advantages over standard two-level VSI, such as greater number of levels in the output voltage waveforms, less harmonic distortion in voltage and current waveforms and lower switching frequencies. This paper emphasizes the derivation of switching states using the Space Vector Pulse Width Modulation (SVPWM technique. The control scheme is implemented using Matlab/Simulink. Experimental results using dSPACE validate the steady-state and the dynamic performance of the proposed control strategy.

  15. Testing of Diode-Clamping in an Inductive Pulsed Plasma Thruster Circuit

    Science.gov (United States)

    Toftul, Alexandra; Polzin, Kurt A.; Martin, Adam K.; Hudgins, Jerry L.

    2014-01-01

    Testing of a 5.5 kV silicon (Si) diode and 5.8 kV prototype silicon carbide (SiC) diode in an inductive pulsed plasma thruster (IPPT) circuit was performed to obtain a comparison of the resulting circuit recapture efficiency,eta(sub r), defined as the percentage of the initial charge energy remaining on the capacitor bank after the diode interrupts the current. The diode was placed in a pulsed circuit in series with a silicon controlled rectifier (SCR) switch, and the voltages across different components and current waveforms were collected over a range of capacitor charge voltages. Reverse recovery parameters, including turn-off time and peak reverse recovery current, were measured and capacitor voltage waveforms were used to determine the recapture efficiency for each case. The Si fast recovery diode in the circuit was shown to yield a recapture efficiency of up to 20% for the conditions tested, while the SiC diode further increased recapture efficiency to nearly 30%. The data presented show that fast recovery diodes operate on a timescale that permits them to clamp the discharge quickly after the first half cycle, supporting the idea that diode-clamping in IPPT circuit reduces energy dissipation that occurs after the first half cycle

  16. Perpendicular magnetic anisotropy influence on voltage-driven spin-diode effect in magnetic tunnel junctions: A micromagnetic study

    Science.gov (United States)

    Frankowski, Marek; Chȩciński, Jakub; Skowroński, Witold; Stobiecki, Tomasz

    2017-05-01

    We study the influence of the perpendicular magnetic anisotropy on the voltage-induced ferromagnetic resonance in magnetic tunnel junctions (MTJs). An MTJ response to the applied radio-frequency voltage excitation is investigated using micromagnetic calculations with the free layer oriented both in-plane and out-of-plane. Our model allows for a quantitative description of the magnetic system parameters such as resonance frequency, sensitivity or quality factor and for a distinction between material-dependent internal damping and disorder-dependent effective damping. We find that the sensitivity abruptly increases up to three orders of magnitude near the anisotropy transition regime, while the quality factor declines due to effective damping increase. We attribute the origin of this behaviour to the changes of the exchange energy in the system, which is calculated using micromagnetic approach.

  17. Comparative Study of Online Open Circuit Voltage Estimation Techniques for State of Charge Estimation of Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Hicham Chaoui

    2017-04-01

    Full Text Available Online estimation techniques are extensively used to determine the parameters of various uncertain dynamic systems. In this paper, online estimation of the open-circuit voltage (OCV of lithium-ion batteries is proposed by two different adaptive filtering methods (i.e., recursive least square, RLS, and least mean square, LMS, along with an adaptive observer. The proposed techniques use the battery’s terminal voltage and current to estimate the OCV, which is correlated to the state of charge (SOC. Experimental results highlight the effectiveness of the proposed methods in online estimation at different charge/discharge conditions and temperatures. The comparative study illustrates the advantages and limitations of each online estimation method.

  18. Impact Study of Electric Vehicle (EV) Integration on Low Voltage (LV) Grids

    DEFF Research Database (Denmark)

    Wu, Qiuwei; Cha, Seung-Tae; Nielsen, Arne Hejde

    2012-01-01

    Large scale deployment of electric vehicles (EVs) has become a very interesting option because it can both reduce the greenhouse gas (GHG) emission from the transport sector and facilitate the integration of more renewable energy resources (RES) by providing the flexibility of EV charging demands....... Although the EV grid integration is promising, the impact of the EV grid integration has to be investigated in order to identify the bottlenecks of power systems for the EV grid integration and assess different charging scenarios. This paper is focused on the impact of EV grid integration on low voltage...

  19. 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.

  20. 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 cord-clamping and infant 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.

  1. The application of the Escherichia coli giant spheroplast for drug screening with automated planar patch clamp system

    Directory of Open Access Journals (Sweden)

    Kyoko Kikuchi

    2015-09-01

    Full Text Available Kv2.1, the voltage-gated ion channel, is ubiquitously expressed in variety of tissues and dysfunction of this ion channel is responsible for multiple diseases. Electrophysiological properties of ion channels are so far characterized with eukaryotic cells using the manual patch clamp which requires skilful operators and expensive equipments. In this research, we created a simple and sensitive drug screen method using bacterial giant spheroplasts and the automated patch clamp which does not require special skills. We expressed a eukaryotic voltage-gated ion channel Kv2.1 in Escherichia coli using prokaryotic codon, and prepared giant spheroplasts large enough for the patch clamp. Human Kv2.1 currents were successfully recorded from giant spheroplasts with the automated system, and Kv2.1-expressed E. coli spheroplasts could steadily reacted to the dose–response assay with TEA and 4-AP. Collectively, our results indicate for the first time that the bacterial giant spheroplast can be applied for practical pharmaceutical assay using the automated patch clamp.

  2. Characterization of voltage-gated ionic currents in a peripheral sensory neuron in larval Drosophila

    Directory of Open Access Journals (Sweden)

    Bate Michael

    2010-06-01

    Full Text Available Abstract Background The development, morphology and genetics of sensory neurons have been extensively studied in Drosophila. Sensory neurons in the body wall of larval Drosophila in particular have been the subject of numerous anatomical studies, however, little is known about the intrinsic electrical properties of larval sensory cells. Findings We performed whole cell patch recordings from an identified peripheral sensory cell, the dorsal bipolar sensory neuron (dbd and measured voltage-gated ionic currents in 1st instar larvae. Voltage clamp analysis revealed that dbds have a TEA sensitive, non-inactivating IK type potassium current as well as a 4-AP sensitive, inactivating IA type potassium current. dbds also show a voltage-gated calcium current (ICa and a voltage-gated sodium current (INa. Conclusions This work provides a first characterization of voltage-activated ionic currents in an identified body-wall sensory neuron in larval Drosophila. Overall, we establish baseline physiology data for future studies aimed at understanding the ionic and genetic basis of sensory neuron function in fruit flies and other model organisms.

  3. Sub-nanosecond time resolved light emission study for diffuse discharges in air under steep high voltage pulses

    Science.gov (United States)

    Tardiveau, P.; Magne, L.; Marode, E.; Ouaras, K.; Jeanney, P.; Bournonville, B.

    2016-10-01

    Pin-to-plane discharges in centimetre air gaps and standard conditions of pressure and temperature are generated under very high positive nanosecond scale voltage pulses. The experimental study is based on recordings of sub-nanosecond time resolved and Abel-processed light emission profiles and their complete correlation to electrical current waveforms. The effects of the voltage pulse features (amplitude between 20 and 90 kV, rise time between 2 and 5.2 ns, and time rate between 4 and 40 kV · ns‑1) and the electrode configuration (gap distance between 10 and 30 mm, pin radius between 10 and 200 µm, copper, molybdenum or tungsten pin material) are described. A three time period development can be found: a glow-like structure with monotonic light profiles during the first 1.5 ns whose size depends on time voltage rate, a shell-like structure with bimodal profiles whose duration and extension in space depends on rise time, and either diffuse or multi-channel regime for the connection to the cathode plane according to gap distance. The transition of the light from monotonic to bimodal patterns reveals the relative effects and dynamics of streamer space charge and external laplacian field. A classical 2D-fluid model for streamer propagation has been used and adapted for very high and steep voltage pulses. It shows the formation of a strong space charge (streamer) very close to the pin, but also a continuity of emission between the pin and the streamer, and electric fields higher than the critical ionization field (28 kV · cm‑1 in air) almost in the whole gap and very early in the discharge propagation.

  4. 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...... 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...

  5. Effect of La3+ on myocardiac potassium channels revealed by patch-clamp technique

    Institute of Scientific and Technical Information of China (English)

    XUE Shaowu; YANG Pin

    2005-01-01

    The effect of La3+ on potassium channels in rat ventricular myocytes was investigated using the whole-cell patch-clamp recording mode. The Ca2+-independent voltage- activated outward K+ current was activated by the depolarizing pulse in enzymatically isolated rat ventricular myocytes. After addition of different concentrations La3+ to the bath solution, the outward K+ current was depressed gradually. The inhibition effect was in a concentration-dependent manner. The phenomena of the outward K+ current, being the main repolarizing current suppressed by La3+, suggest that the effect of lanthanides on myocardial function should be exploited further.

  6. 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...

  7. Kinetics properties of voltage induced colicin Ia channels into a lipid bilayer

    CERN Document Server

    Cassia-Moura, R

    1998-01-01

    The activation kinetics of the ion channels formed by colicin Ia incorporated into a planar bilayer lipid membrane (BLM) was investigated by the voltage clamp technique using different step voltage stimuli. The temporal behaviour of ion channels put in evidence a gain or a loss of memory, revealed by a specific sequence of electrical pulses used for stimulation.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  9. Modelling and control of a seven level NPC voltage source inverter. Application to high power induction machine drive

    Energy Technology Data Exchange (ETDEWEB)

    Gheraia, H.; Berkouk, E.M. [ENP, Alger (Algeria). Lab. de Commande des Processus; Manesse, G. [CNAM-Paris (France). Lab. d' Electricite Industrielle

    2001-08-01

    In this paper, we study a new kind of continuous-alternating converters: a seven-level neutral point clamping (NPC) voltage source inverter (VSI). We propose this inverter for applications in high voltage and high power fields. In the first part, we develop the knowledge and the control models of this inverter using the connections functions of the semi-conductors. After that, we present two pulse width modulation (PWM) algorithms to control this converter using its control model. We propose these algorithms for digital implementation. This multilevel inverter is associated to the induction machine. The performances obtained are full of promise to use it in the high voltage and high power fields of electrical traction. (orig.)

  10. Study on Miniaturized UHF Antennas for Partial Discharge Detection in High-Voltage Electrical Equipment.

    Science.gov (United States)

    Liu, Jingcun; Zhang, Guogang; Dong, Jinlong; Wang, Jianhua

    2015-11-20

    Detecting partial discharge (PD) is an effective way to evaluate the condition of high-voltage electrical equipment insulation. The UHF detection method has attracted attention due to its high sensitivity, strong interference resistance, and ability to locate PDs. In this paper, a miniaturized equiangular spiral antenna (ESA) for UHF detection that uses a printed circuit board is proposed. I-shaped, L-shaped, and C-shaped microstrip baluns were designed to match the impedance between the ESA and coaxial cable and were verified by a vector network analyzer. For comparison, three other types of UHF antenna were also designed: A microstrip patch antenna, a microstrip slot antenna, and a printed dipole antenna. Their antenna factors were calibrated in a uniform electric field of different frequencies modulated in a gigahertz transverse electromagnetic cell. We performed comparison experiments on PD signal detection using an artificial defect model based on the international IEC 60270 standard. We also conducted time-delay test experiments on the ESA sensor to locate a PD source. It was found that the proposed ESA sensor meets PD signal detection requirements. The sensor's compact size makes it suitable for internal installation in high-voltage electrical equipment.

  11. Study of Low Voltage Ride Through Performance for Wind Power Generation with Doubly Fed Induction Generator

    Science.gov (United States)

    Hirawata, Ryoya; Kai, Takaaki

    Recently, the introduction of wind power generation is increasing rapidly. The ratio of wind power generation to the capacity of a total generation is getting higher and higher. When the phase-to-phase fault occurs in the power system, the frequency of power system is lower due to disconnecting of the wind power generation with doubly fed induction generator (DFIG). Therefore, the power system might become unstable. This paper describes the LVRT (low voltage ride through) performance improvement scheme of the wind power generation with DFIG. The wind power generation is disconnected from the grid in case of the power system fault. It is independently in operation from the grid by controlling of the inverter equipped in the generation. After clearance of the power system fault, the wind power generation is immediately re-connected to the grid. As a result, instability in the power system disappears. The performance of LVRT is confirmed by using simulation software PSCAD/EMTDC. The simulation result shows an excellent result to the three-phase short-circuit fault of the voltage dip 100%.

  12. Study on Miniaturized UHF Antennas for Partial Discharge Detection in High-Voltage Electrical Equipment

    Directory of Open Access Journals (Sweden)

    Jingcun Liu

    2015-11-01

    Full Text Available Detecting partial discharge (PD is an effective way to evaluate the condition of high-voltage electrical equipment insulation. The UHF detection method has attracted attention due to its high sensitivity, strong interference resistance, and ability to locate PDs. In this paper, a miniaturized equiangular spiral antenna (ESA for UHF detection that uses a printed circuit board is proposed. I-shaped, L-shaped, and C-shaped microstrip baluns were designed to match the impedance between the ESA and coaxial cable and were verified by a vector network analyzer. For comparison, three other types of UHF antenna were also designed: A microstrip patch antenna, a microstrip slot antenna, and a printed dipole antenna. Their antenna factors were calibrated in a uniform electric field of different frequencies modulated in a gigahertz transverse electromagnetic cell. We performed comparison experiments on PD signal detection using an artificial defect model based on the international IEC 60270 standard. We also conducted time-delay test experiments on the ESA sensor to locate a PD source. It was found that the proposed ESA sensor meets PD signal detection requirements. The sensor’s compact size makes it suitable for internal installation in high-voltage electrical equipment.

  13. Timing of umbilical cord clamping after birth for optimizing placental transfusion.

    Science.gov (United States)

    Raju, Tonse N K

    2013-04-01

    A brief delay in clamping the umbilical cord after birth offers health benefits to the newborn, with no adverse effects to the mother or her infant. Yet, in most obstetric practice, the cord is clamped soon after birth. A summary of the current evidence on delayed cord clamping and some reasons for the disconnect between the evidence and practice are discussed here, along with the recommendations from professional organizations and societies about this practice. In term infants, umbilical cord clamping between 30 and 180 s after birth results in higher concentrations of hemoglobin and hematocrit during the neonatal period, and increased serum ferritin levels and a lower incidence of iron-deficiency anemia at 4-6 months of age. These are important benefits for children in low and middle income countries where iron-deficiency anemia is highly prevalent. In preterm infants, delayed cord clamping for at least 30 s increases the concentrations of hemoglobin and hematocrit, improves mean systemic blood pressure, urine output, and cardiac function, and decreases the need for vasopressors and blood transfusions during the neonatal period. It also decreases the prevalence of necrotizing enterocolitis, sepsis, and intraventricular hemorrhage (all grades). Milking of the unclamped umbilical cord toward the infant soon after birth also has similar beneficial effects. In some studies, more infants in the delayed cord clamping groups required phototherapy for jaundice. Many professional organizations, societies, and experts recommend at least a 30-s delay before clamping the umbilical cord, especially after preterm births. The value of this practice for term births in resource-rich settings has not been evaluated.

  14. Obstetricians' attitudes and beliefs regarding umbilical cord clamping.

    Science.gov (United States)

    Jelin, Angie C; Kuppermann, Miriam; Erickson, Kristine; Clyman, Ronald; Schulkin, Jay

    2014-09-01

    Although delayed umbilical cord clamping has been demonstrated to reduce the incidence of intraventricular hemorrhage and neonatal sepsis, and decrease the need for neonatal transfusions (without affecting cord pH, Apgar scores or the need for phototherapy), the extent to which this practice is being employed is unknown. We conducted a survey of US obstetricians to assess their attitudes and beliefs about cord clamping. Questionnaires were randomly mailed to members of the American College of Obstetricians and Gynecologists (ACOG), and the Collaborative Ambulatory Research Network (CARN). The data were analyzed using Chi-square and Student t tests. The response rates for the CARN and other ACOG members were 47% and 21%, respectively. Most (88%) responders reported their hospital had no umbilical cord clamping policy. The most frequent response for optimal timing of umbilical cord clamping, regardless of gestational age, was "don't know". Potential for neonatal red blood cell transfusion was the only concern cited as a reason for being somewhat or very inclined to delay umbilical cord clamping (51%). Delayed neonatal resuscitation (76%) was listed as a reason to clamp the cord immediately, despite the paucity of literature to support immediate cord clamping in this cohort. Despite substantial evidence supporting the practice of delayed cord clamping, few institutions have policies regarding this practice. Moreover, obstetricians' beliefs about the appropriate timing for umbilical cord clamping are not consistent with the evidence that demonstrates its beneficial impact on neonatal outcomes.

  15. Delayed cord clamping and cord gas analysis at birth.

    Science.gov (United States)

    Xodo, Serena; Xodo, Luigi; Berghella, Vincenzo

    2017-09-16

    Delayed cord clamping for at least 60 seconds in both term and preterm babies is a major recent change in clinical care. Delayed cord clamping has several effects on other possible interventions. One of these is the effect of delayed cord clamping on umbilical artery gas analysis. When indicated, umbilical artery gas analysis can safely be done either with early cord clamping, or, probably most of the times it is necessary, during delayed cord clamping with the cord still unclamped. Paired blood samples (one from the umbilical artery and one from the umbilical vein) can be taken from the pulsating and unclamped cord, immediately after birth, during delayed cord clamping, without any effect on either the accuracy of umbilical artery gas analysis or on the transfusion of blood through delayed cord clamping. Umbilical artery gas analysis should instead not be done after delayed cord clamping, since delayed cord clamping alters several acid-based parameters and lactate values. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  16. Voltage Swells Improvement in Low Voltage Network Using Dynamic Voltage Restorer

    Directory of Open Access Journals (Sweden)

    R. Omar

    2011-01-01

    Full Text Available Problem statement: Voltage disturbances are the most common power quality problem due to the increased use of a large numbers of sophisticated electronic equipment in industrial distribution system. The voltage disturbances such as voltage sags, swells, harmonics, unbalance and flickers. High quality in the power supply is needed, since failures due to such disturbances usually have a high impact on production cost. There are many different solutions to compensate voltage disturbances but the use of a DVR is considered to be the most cost effective method. The objective of this study is to propose a new topology of a DVR in order to mitigate voltage swells using a powerful power custom device namely the Dynamic Voltage Restorer (DVR. Approach: New configuration of a DVR with an improvement of a controller based on direct-quadrature-zero method has been introduced to compensate voltage swells in the network. Results: The effectiveness of the DVR with its controller were verify using Matlab/Simulinks SimPower Toolbox and then implemented using 5KVA DVR experimental setup. Simulations and experimental results demonstrate the effective dynamic performance of the proposed configuration. Conclusion: The implimentation of the proposed DVR validate the capabilities in mitigating of voltage swells effectiveness.During voltage swells, the DVR injects an appropriate voltage to maintain the load voltage at its nominal value.

  17. Illuminating Myocyte-Fibroblast Homotypic and Heterotypic Gap Junction Dynamics Using Dynamic Clamp.

    Science.gov (United States)

    Brown, Tashalee R; Krogh-Madsen, Trine; Christini, David J

    2016-08-23

    Fibroblasts play a significant role in the development of electrical and mechanical dysfunction of the heart; however, the underlying mechanisms are only partially understood. One widely studied mechanism suggests that fibroblasts produce excess extracellular matrix, resulting in collagenous septa that slow propagation, cause zig-zag conduction paths, and decouple cardiomyocytes, resulting in a substrate for cardiac arrhythmia. An emerging mechanism suggests that fibroblasts promote arrhythmogenesis through direct electrical interactions with cardiomyocytes via gap junction (GJ) channels. In the heart, three major connexin (Cx) isoforms, Cx40, Cx43, and Cx45, form GJ channels in cell-type-specific combinations. Because each Cx is characterized by a unique time- and transjunctional voltage-dependent profile, we investigated whether the electrophysiological contributions of fibroblasts would vary with the specific composition of the myocyte-fibroblast (M-F) GJ channel. Due to the challenges of systematically modifying Cxs in vitro, we coupled native cardiomyocytes with in silico fibroblast and GJ channel electrophysiology models using the dynamic-clamp technique. We found that there is a reduction in the early peak of the junctional current during the upstroke of the action potential (AP) due to GJ channel gating. However, effects on the cardiomyocyte AP morphology were similar regardless of the specific type of GJ channel (homotypic Cx43 and Cx45, and heterotypic Cx43/Cx45 and Cx45/Cx43). To illuminate effects at the tissue level, we performed multiscale simulations of M-F coupling. First, we developed a cell-specific model of our dynamic-clamp experiments and investigated changes in the underlying membrane currents during M-F coupling. Second, we performed two-dimensional tissue sheet simulations of cardiac fibrosis and incorporated GJ channels in a cell type-specific manner. We determined that although GJ channel gating reduces junctional current, it does not

  18. Trail without Catheter after Transurethral Resection of Prostate: Clamp It or Not?

    Directory of Open Access Journals (Sweden)

    Vikash Talreja

    2016-01-01

    Full Text Available Background. There has been argument between clinical practitioners about clamping catheter or not prior to its removal after transurethral resection of prostate (TURP. We conducted a clinical trial to assess whether clamping has any role in early bladder tone recovery particularly in patients who undergo TURP. Methods. Randomized clinical trial was conducted at a tertiary care hospital, Karachi from January 2014 to July 2015. Eighty-six study participants who underwent TURP were randomly allocated into two groups of 43 participants each. In Group I, patient’s Foley catheter was not clamped prior to its removal and in Group II Foley catheter was clamped. Data of all subjects were analyzed using SPSS version 20. Results. There was no significant difference in age and weight of resected tissues between two groups. Among 4 patients in Group I who required recatheterization, 1 patient was discharged with catheter as compared to Group II in which 2 patients were discharged with catheter (P=0.99. Only 1 patient (2.3% in Group II had bleeding which required recatheterization. Length of stay was significantly affected by early and free removal of Foley catheter (P<0.001. Conclusion. The results of current study identified that clamping whether done or not had no significant impact on urinary retention.

  19. Characterization and performance studies of high-voltage CMOS based pixel sensors

    CERN Document Server

    Smaranda, Dumitru Dan

    2015-01-01

    The high luminosity upgrade of the LHC will push the limits for detectors, specially the silicon trackers which are closest to the interaction point. The ATLAS CMOS Sensor R&D efort is investigating a new technology using high-voltage CMOS processes for producing pixel and strip sensors. In contrast to the currently used technology these devices implement active electronics on the sensor itself, offering a multitude of tuning parameters for achieving the best performance. My summer project revolved around characterising existing samples along with assembling and debugging hardware required for their improvement and functionality. Other tasks involved writing communication protocols using pyBAR to remotely control injection circuitry on a GPAC card, and helping various members of the group with data collection and analysis. Through the summer student programme I have had the opportunity to be part of a vibrant scientic community at the forefront of research, to create bonds with fellow students from univ...

  20. A Study on Power Quality Improvement in PWM Controlled AC Voltage Controller

    Directory of Open Access Journals (Sweden)

    Ahmet ALTINTAŞ

    2009-04-01

    Full Text Available A lot of topologies of pulse-width modulated (PWM-AC controllers for single-phase and three-phase systems are proposed up to date. PWM-AC controllers have important advantages compared with the phase-controlled AC controllers using thyristors and triacs. The PWM-AC controller has sinusoidal current waveforms, smaller THD values, better power factor, faster dynamics, and smaller input/output filter. This article presents a novel control technique for application to PWM-AC controllers with ability of generating fewer harmonics. In the proposed control method, both the traditional AC voltage controllers and the PWM-AC controllers are combined; and smaller THD values are obtained. Thus, the harmonic pollution in the power system will be reduced; and consequently, the power quality will be increased. For this purpose, computer simulations are performed in order to investigate the proposed controller performance. The obtained results are compared with the conventional PWM-AC controller.

  1. Accurate Switched-Voltage voltage averaging circuit

    OpenAIRE

    金光, 一幸; 松本, 寛樹

    2006-01-01

    Abstract ###This paper proposes an accurate Switched-Voltage (SV) voltage averaging circuit. It is presented ###to compensated for NMOS missmatch error at MOS differential type voltage averaging circuit. ###The proposed circuit consists of a voltage averaging and a SV sample/hold (S/H) circuit. It can ###operate using nonoverlapping three phase clocks. Performance of this circuit is verified by PSpice ###simulations.

  2. FUNDAMENTAL RESONANCE AND BIFURCATION OF LARGE GENERATOR END WINDING WHEN ITS CLAMPING PLATES ARE LOOSE

    Institute of Scientific and Technical Information of China (English)

    HU Yu-da; QIU Jia-jun; TA Na

    2005-01-01

    Vibration problems of a segment of winding between two clamping plates are studied when the clamping plates, which are used to fix stator end winding, are loose. First,magnetic induction expressions of the winding while the generator was running were given by using separation of variables method. Also, the expressions of the winding electromagnetic force and dry friction force between loosing clamping plates were gotten. Secondly, a mechanical model, which was used to study nonlinear vibration problem of the winding, was set up. Fundamental resonance was analyzed by using multiple scales method, and a resonance equation of amplitude and frequency in steady state was given. Then stability,bifurcation and singularity of the steady solution were studied. Criterions of stability and transition set of the bifurcation equation were obtained. At last, through numerical calculations, resonance curves were obtained. The results are helpful for analysis and protection of generator accidents.

  3. High voltage load resistor array

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Modulation of voltage-gated sodium channels hyperpolarizes the voltage threshold for activation in spinal motoneurones.

    Science.gov (United States)

    Power, Kevin E; Carlin, Kevin P; Fedirchuk, Brent

    2012-03-01

    Previous work has shown that motoneurone excitability is enhanced by a hyperpolarization of the membrane potential at which an action potential is initiated (V(th)) at the onset, and throughout brainstem-evoked fictive locomotion in the adult decerebrate cat and neonatal rat. Modeling work has suggested the modulation of Na(+) conductance as a putative mechanism underlying this state-dependent change in excitability. This study sought to determine whether modulation of voltage-gated sodium channels could induce V(th) hyperpolarization. Whole-cell patch-clamp recordings were made from antidromically identified lumbar spinal motoneurones in an isolated neonatal rat spinal cord preparation. Recordings were made with and without the bath application of veratridine, a plant alkaloid neurotoxin that acts as a sodium channel modulator. As seen in HEK 293 cells expressing Nav1.2 channels, veratridine-modified channels demonstrated a hyperpolarizing shift in their voltage-dependence of activation and a slowing of inactivation that resulted in an enhanced inward current in response to voltage ramp stimulations. In the native rat motoneurones, veratridine-modified sodium channels induced a hyperpolarization of V(th) in all 29 neonatal rat motoneurones examined (mean hyperpolarization: -6.6 ± 4.3 mV). V(th) hyperpolarization was not due to the effects on Ca(2+) and/or K(+) channels as blockade of these currents did not alter V(th). Veratridine also significantly increased the amplitude of persistent inward currents (PICs; mean increase: 72.5 ± 98.5 pA) evoked in response to slow depolarizing current ramps. However, the enhancement of the PIC amplitude had a slower time course than the hyperpolarization of V(th), and the PIC onset voltage could be either depolarized or hyperpolarized, suggesting that PIC facilitation did not mediate the V(th) hyperpolarization. We therefore suggest that central neuronal circuitry in mammals could affect V(th) in a mechanism similar to that of

  5. The PCNA-RFC families of DNA clamps and clamp loaders.

    Science.gov (United States)

    Majka, Jerzy; Burgers, Peter M J

    2004-01-01

    The proliferating cell nuclear antigen PCNA functions at multiple levels in directing DNA metabolic pathways. Unbound to DNA, PCNA promotes localization of replication factors with a consensus PCNA-binding domain to replication factories. When bound to DNA, PCNA organizes various proteins involved in DNA replication, DNA repair, DNA modification, and chromatin modeling. Its modification by ubiquitin directs the cellular response to DNA damage. The ring-like PCNA homotrimer encircles double-stranded DNA and slides spontaneously across it. Loading of PCNA onto DNA at template-primer junctions is performed in an ATP-dependent process by replication factor C (RFC), a heteropentameric AAA+ protein complex consisting of the Rfc1, Rfc2, Rfc3, Rfc4, and Rfc5 subunits. Loading of yeast PCNA (POL30) is mechanistically distinct from analogous processes in E. coli (beta subunit by the gamma complex) and bacteriophage T4 (gp45 by gp44/62). Multiple stepwise ATP-binding events to RFC are required to load PCNA onto primed DNA. This stepwise mechanism should permit editing of this process at individual steps and allow for divergence of the default process into more specialized modes. Indeed, alternative RFC complexes consisting of the small RFC subunits together with an alternative Rfc1-like subunit have been identified. A complex required for the DNA damage checkpoint contains the Rad24 subunit, a complex required for sister chromatid cohesion contains the Ctf18 subunit, and a complex that aids in genome stability contains the Elg1 subunit. Only the RFC-Rad24 complex has a known associated clamp, a heterotrimeric complex consisting of Rad17, Mec3, and Ddc1. The other putative clamp loaders could either act on clamps yet to be identified or act on the two known clamps.

  6. Voltage-dependent K channels in protoplasts of trap-lobe cells of Dionaea muscipula.

    Science.gov (United States)

    Iijima, T; Hagiwara, S

    1987-01-01

    The outward rectification of the K+ current in mesophyll cell protoplasts from trap-lobes of Dionaea muscipula was studied with the patch-clamp technique. The rectification had instantaneous and time-dependent components. Changes in [K+]i strongly affected the conductance voltage relation of the plasma membrane while changes in [K+]o had little effect on the relation. Thus, the outward rectification depends on the membrane voltage and the concentration of intracellular K+. Corresponding single-channel activities were observed both in the intact membrane (cell-attached recording) and in excised patches. The single-channel conductance was about 3.3 pS with symmetrical solutions containing 30 mM K+.

  7. 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.

  8. 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.

  9. A DTC Algorithm for Induction Motor Drives with 3-level Diode-Clamped Inverters

    Directory of Open Access Journals (Sweden)

    M. Cirrincione

    2005-12-01

    Full Text Available This paper presents a novel Direct Torque Control (DTC algorithm for induction motor electrical drives supplied by 3-level diode clamped inverters. It is the natural extension of the classic Switching Table (ST based DTC, modified for a 3-level inverter supply. It presents also a very simple algorithm for the minimization of the capacitor voltage ripple. Results obtained with numerical simulations show that the employment of a 3-level inverter in such a control scheme permits to obtain the same dynamical performances as those obtained with a 2-level inverter with resulting lower torque and flux ripples as well as a lower harmonic content in the stator voltages and currents. Some considerations about the consequent benefits as for EMC of this drive are also presented.

  10. Sequential dissection of multiple ionic currents in single cardiac myocytes under action potential-clamp.

    Science.gov (United States)

    Banyasz, Tamas; Horvath, Balazs; Jian, Zhong; Izu, Leighton T; Chen-Izu, Ye

    2011-03-01

    The cardiac action potential (AP) is shaped by myriad ionic currents. In this study, we develop an innovative AP-clamp Sequential Dissection technique to enable the recording of multiple ionic currents in the single cell under AP-clamp. This new technique presents a significant step beyond the traditional way of recording only one current in any one cell. The ability to measure many currents in a single cell has revealed two hitherto unknown characteristics of the ionic currents in cardiac cells: coordination of currents within a cell and large variation of currents between cells. Hence, the AP-clamp Sequential Dissection method provides a unique and powerful tool for studying individual cell electrophysiology.

  11. Minimum Normal Force Principle Based Quantitive Optimizationof Clamping Forces for Thin Walled Part

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fa-ping; SUN Hou-fang; SHAHID I.Butt

    2008-01-01

    Based on the stability criteria of workpiece-fixture system, quantitative optimization of clamping forces during precise machining process for thin walled part is studied considering the contact condition between wokpiece and locator, the contact mechanical model is achieved ,which is further been used to calculate the entire passive forces acting on the statically undetermined workpiece by means of the force screw theory as well as minimum norm force principle. Furthermore, a new methodology to optimize clamping forces is put forward, on the criteria of keeping the stability of workpiece during cutting process. By this way, the intensity of clamping forces is decreased dramatically, which will be most beneficial for improving the machining quality of thin-walled parts. Finally, a case study is used to support and validate the proposed model.

  12. 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

  13. Direct Effect of Remifentanil and Glycine Contained in Ultiva® on Nociceptive Transmission in the Spinal Cord: In Vivo and Slice Patch Clamp Analyses

    Science.gov (United States)

    Sumie, Makoto; Shiokawa, Hiroaki; Yamaura, Ken; Karashima, Yuji; Hoka, Sumio; Yoshimura, Megumu

    2016-01-01

    Background 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. Methods 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. Results 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. Conclusions 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

  14. [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

  15. Analysis of Contact Characteristic of Overhead Line and Suspension Clamp

    Directory of Open Access Journals (Sweden)

    Zhao Xinze

    2013-01-01

    Full Text Available In this paper, a LGJ150/25 type ACSR transmission line and a CGU-3 type suspension clamp are taken as research objects. A contact model of the conductor and the clamp was established by using finite element method. The effects of sag angle of the conductor, holding force and tension force in section are analyzed. The results showed that the contact area in the middle of the clamp is of belt-like type. The extreme values of tress were observed on the edge of the contact area and near the edge of keeper. In clamp section, suspension angle had the greatest influence on contact stress, and then the clamp force. The tension force in section played a most important role in these affecting factors. In the exit section of clamp, the biggest impact factor was tension force in this section, then the suspension angle, the third was clamp force. The results provide theoretical basis on reducing corona loss, optimization the clamp. Doubtlessly, the conclusion has important theoretical significance and application value.

  16. OPTIMAL TIMING FOR CLAMPING THE UMBILICAL CORD AFTER BIRTH

    Science.gov (United States)

    Raju, Tonse N. K.; Singal, Nalini

    2013-01-01

    Synopsis This paper provides a brief overview of pros and cons of clamping the cord too early (within seconds) after birth. It also highlights evolving data that suggests that delaying cord clamping for 30–60 seconds after birth is beneficial to the baby and the mother, with no measurable negative effects. PMID:23164185

  17. 21 CFR 876.5160 - Urological clamp for males.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Urological clamp for males. 876.5160 Section 876.5160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5160 Urological clamp for...

  18. Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes.

    Science.gov (United States)

    McDonald, Susan J; Middleton, Philippa; Dowswell, Therese; Morris, Peter S

    2013-07-11

    Policies for timing of cord clamping vary, with early cord clamping generally carried out in the first 60 seconds after birth, whereas later cord clamping usually involves clamping the umbilical cord more than one minute after the birth or when cord pulsation has ceased. The benefits and potential harms of each policy are debated. To determine the effects of early cord clamping compared with late cord clamping after birth on maternal and neonatal outcomes We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (13 February 2013). Randomised controlled trials comparing early and late cord clamping. Two review authors independently assessed trial eligibility and quality and extracted data. We included 15 trials involving a total of 3911 women and infant pairs. We judged the trials to have an overall moderate risk of bias. Maternal outcomes: No studies in this review reported on maternal death or on severe maternal morbidity. There were no significant differences between early versus late cord clamping groups for the primary outcome of severe postpartum haemorrhage (risk ratio (RR) 1.04, 95% confidence interval (CI) 0.65 to 1.65; five trials with data for 2066 women with a late clamping event rate (LCER) of ~3.5%, I(2) 0%) or for postpartum haemorrhage of 500 mL or more (RR 1.17 95% CI 0.94 to 1.44; five trials, 2260 women with a LCER of ~12%, I(2) 0%). There were no significant differences between subgroups depending on the use of uterotonic drugs. Mean blood loss was reported in only two trials with data for 1345 women, with no significant differences seen between groups; or for maternal haemoglobin values (mean difference (MD) -0.12 g/dL; 95% CI -0.30 to 0.06, I(2) 0%) at 24 to 72 hours after the birth in three trials. Neonatal outcomes: There were no significant differences between early and late clamping for the primary outcome of neonatal mortality (RR 0.37, 95% CI 0.04 to 3.41, two trials, 381 infants with a LCER of ~1%), or for most other

  19. A Test Study of 50% Lightning Impulse Breakdown Voltage on Rod-Plane Gap with Two-Phase Mixture of Gas and Solid Particles

    Science.gov (United States)

    He, Zhenghao; Xu, Huaili; Bai, Jing; Yu, Fusheng; Hu, Feng; Li, Jin

    2007-12-01

    A test study on 50% lightning impulse breakdown voltage in two-phase mixture of gas and solid particles has been carried out in a specially designed discharge cabinet. A mechanical sieve is set up for sifting different solid particles into the discharge space uniformly. The lightning impulse voltage according with international electro-technical commission (IEC) standard is applied to the electrodes inside the discharge cabinet by the rule of up-down method in a total of 40 times. The results showed that the 50% lightning impulse breakdown voltage in two-phase mixture of gas and solid particles has its own features and is much different from that in air.

  20. 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

  1. Study on the Mathematical Model of Dielectric Recovery Characteristics in High Voltage SF6 Circuit Breaker

    Science.gov (United States)

    Lin, Xin; Wang, Feiming; Xu, Jianyuan; Xia, Yalong; Liu, Weidong

    2016-03-01

    According to the stream theory, this paper proposes a mathematical model of the dielectric recovery characteristic based on the two-temperature ionization equilibrium equation. Taking the dynamic variation of charged particle's ionization and attachment into account, this model can be used in collaboration with the Coulomb collision model, which gives the relationship of the heavy particle temperature and electron temperature to calculate the electron density and temperature under different pressure and electric field conditions, so as to deliver the breakdown electric field strength under different pressure conditions. Meanwhile an experiment loop of the circuit breaker has been built to measure the breakdown voltage. It is shown that calculated results are in conformity with experiment results on the whole while results based on the stream criterion are larger than experiment results. This indicates that the mathematical model proposed here is more accurate for calculating the dielectric recovery characteristic, it is derived from the stream model with some improvement and refinement and has great significance for increasing the simulation accuracy of circuit breaker's interruption characteristic. supported by Science and Technology Project of State Grid Corporation of China (No. GY17201200063), National Natural Science Foundation of China (No. 51277123), Basic Research Project of Liaoning Key Laboratory of Education Department (LZ2015055)

  2. Quantitative Analysis Linking Inner Hair Cell Voltage Changes and Postsynaptic Conductance Change: A Modelling Study

    Directory of Open Access Journals (Sweden)

    Andreas N. Prokopiou

    2015-01-01

    Full Text Available This paper presents a computational model which estimates the postsynaptic conductance change of mammalian Type I afferent peripheral process when airborne acoustic waves impact on the tympanic membrane. A model of the human auditory periphery is used to estimate the inner hair cell potential change in response to airborne sound. A generic and tunable topology of the mammalian synaptic ribbon is generated and the voltage dependence of its substructures is used to calculate discrete and probabilistic neurotransmitter vesicle release. Results suggest an almost linear relationship between increasing sound level (in dB SPL and the postsynaptic conductance for frequencies considered too high for neurons to phase lock with (i.e., a few kHz. Furthermore coordinated vesicle release is shown for up to 300–400 Hz and a mechanism of phase shifting the subharmonic content of a stimulating signal is suggested. Model outputs suggest that strong onset response and highly synchronised multivesicular release rely on compound fusion of ribbon tethered vesicles.

  3. First-Principles Electronic Structure Studies of the Current-Voltage Characteristics of Molecular Nanostructures

    Science.gov (United States)

    Pati, Ranjit; Karna, Shashi P.

    2001-03-01

    Recent advancements in the experimental measurement of conductance across a single molecule(M. A. Reed et al, Science, 278) , 252 (1997). have generated great deal of interest in the feasibility of molecular electronic devices. A successful realization of molecule based electronic devices rests on a detailed understanding of the physical principles underlying controlled transport of electron/hole across molecular units. In order to develop such a fundamental understanding, we have investigated current-voltage characteristics of metal atom (Ag, Au) substituted 1,4-dithiobenzene within Green's function approach according to Datta and coworkers( W. Tian et al, J. Chem. Phys., 109), 2874 (1998).. Ab initio Hamiltonian matrix elements are used to construct the Green's function. The calculated conductance spectrum for the molecule with S bonded to Au atoms qualitatively agrees with the experiment^1. However, large quantitative difference between the calculated and measured conductance is noted. The Au and Ag bonded 1,4-dithiobenzene molecules exhibit marked difference in their resistance and conductance spectra. The conductance of the Ag-bonded molecule is calculated to be about 1.5 times larger than that bonded with Au.

  4. Adaptive PI controller to voltage regulation in power systems: STATCOM as a case study.

    Science.gov (United States)

    Tavana, Mohammad Reza; Khooban, Mohammad-Hassan; Niknam, Taher

    2017-01-01

    Static synchronous compensator (STATCOM) provides the means to improve quality and reliability of a power system as it has the functional capability to handle dynamic disturbances, such as transient stability and power oscillation damping as well as to providing voltage regulation. In this paper, a robust adaptive PI-based optimal fuzzy control strategy is proposed to control a STATCOM used in distribution systems. The proposed intelligent strategy is based on a combination of a new General Type-II Fuzzy Logic (GT2FL) with a simple heuristic algorithm named Teaching Learning Based Optimization (TLBO) Algorithm. The proposed framework optimally tunes parameters of a Proportional-Integral (PI) controller which, similar to most of other researchers regarding control of STATCOM, are in charge of controlling the device. The proposed controller guaranties robustness and stability against uncertainties caused by external disturbances or ever-changing nature of the power systems. The TLBO optimizes the parameters of the controller as well as the input and output membership functions. To validate the efficiency of the proposed controller, the obtained simulation results are compared with those of the two most recent researches applied in this field, namely, conventional Proportional Integral (PI) controller and Optimal Fuzzy PI (OFPI) controller. Results demonstrate the successfulness and effectiveness of the proposed online-TLBO General Type-2 Fuzzy PI (OGT2FPI) controller and its superiority over conventional approaches.

  5. Abatement cost of SF6 emissions from medium voltage switchgear. Validation of recent studies for the European Commission

    Energy Technology Data Exchange (ETDEWEB)

    Benner, J.; Van Lieshout, M.; Croezen, H.

    2012-05-15

    Sulphur hexafluoride (SF6) is a gas with applications including use as an insulator and switching medium in medium voltage (MV) switchgear. While having certain unique properties, it is also a greenhouse gas, with a 22,800 times greater impact than CO2 and an atmospheric lifetime of over 3,000 years. Although the use of SF6 in MV switchgear can be avoided, according to recent studies for the European Commission, the abatement costs are high. This study validates the calculated cost levels as well as the general feasibility of determining a fixed cost figure for this purpose. This analysis yields a result which differs from the earlier studies, particularly with respect to the cost aspect, but also in other areas. CE Delft concludes that for the majority of applications cost-effective SF6-free options are available, leading to abatement costs for the use of SF6 in MV switchgear that range from - 40 to 0 euro/tCO2 eq., for all types of switchgear, with voltage levels below 25 kV and situated on relatively dry locations.

  6. 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.

  7. 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.

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

    Science.gov (United States)

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

    2015-09-01

    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 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.

  9. Alternative positions for the baby at birth before clamping the umbilical cord.

    Science.gov (United States)

    Airey, Rebecca J; Farrar, Diane; Duley, Lelia

    2010-10-06

    The third stage of labour is from birth of the baby until delivery of the placenta. Clamping the umbilical cord is one component of active management of the third stage. Deferring cord clamping allows blood flow between the baby and the placenta to continue; net transfer to the baby is called placental transfusion. If the cord is clamped immediately placental transfusion is restricted. Gravity is one of several factors that may influence the volume and duration of placental transfusion at both vaginal and caesarean births. Hence raising or lowering the baby whilst the cord is intact may influence placental transfusion, which in turn may affect outcome for the baby and the woman. To compare the effects of alternative positions for the baby between birth and cord clamping on outcome for the baby, outcome for the mother and on use of health service resources. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (July 2010). Randomised trials comparing alternative positions for the baby at vaginal and caesarean birth, before clamping of the umbilical cord. We independently assessed trial eligibility and quality. When necessary, we contacted study authors for additional information. Thirty-seven studies (7559 mother-infant pairs) were excluded: 33 (7296) because they did not compare alternative positions for the baby before clamping the umbilical cord and four (263) due to quasi-random allocation. No studies met the inclusion criteria. One additional trial is ongoing. No randomised trials have assessed the influence of gravity on placental transfusion. Large, well-designed randomised trials are needed to assess whether gravity influences placental transfusion at vaginal and caesarean births and, if so, whether this affects short-term and long-term outcome for the baby and for the mother.

  10. Utilization of low voltage D-T neutron generators in neutron physics studies

    Energy Technology Data Exchange (ETDEWEB)

    Singkarat, S.

    1995-08-01

    In a small nuclear laboratory of a developing country a low voltage D-T neutron generator can be a very useful scientific apparatus. Such machines have been used successfully for more than 40 years in teaching and scientific research. The original continuous mode 150-kV D-T neutron generator has been modified to have also a capability of producing 2-ns pulsed neutrons. Together with a carefully designed 10 m long flight path collimator and shielding of a 25 cm diameter {center_dot} 10 cm thick BC-501 neutron detector, the pulsing system was successfully used for measuring the double differential cross-section (DDX) of natural iron for 14.1-MeV neutron from the angle of 30 deg to 150 deg in 10 deg steps. In order to extend the utility of the generator, two methods for converting the almost monoenergetic 14-MeV neutrons to monoenergetic neutrons of lower energy were proposed and tested. The first method uses a pulsed neutron generator and the second method uses an ordinary continuous mode generator. The latter method was successfully used to measure the scintillation light output of a 1.4 cm diameter spherical NE-213 scintillation detector. The neutron generator has also been used in the continuous search for improved neutron detection techniques. There is a proposal, based on Monte Carlo calculations, of using a scintillation fiber for a fast neutron spectrometer. Due to the slender shape of the fiber, the pattern of produced light gives a peak in the pulse height spectrum instead of the well-known rectangular-like distribution, when the fiber is bombarded end-on by a beam of 14-MeV neutrons. Experimental investigations were undertaken. Detailed investigations on the light transportation property of a short fiber were performed. The predicted peak has not yet been found but the fiber detector may be developed as a directional discrimination fast neutron detector. 18 refs.

  11. Cerebral oxygenation and processed EEG response to clamping and shunting during carotid endarterectomy under general anesthesia.

    Science.gov (United States)

    Perez, William; Dukatz, Christopher; El-Dalati, Sami; Duncan, James; Abdel-Rasoul, Mahmoud; Springer, Andrew; Go, Michael R; Dzwonczyk, Roger

    2015-12-01

    Clamping and shunting during carotid endarterectomy (CEA) surgery causes changes in cerebral blood flow. The purpose of this study was to assess and compare, side by side, the cerebral oxygenation (rSO2) and processed electroencephalogram (EEG) response bilaterally to carotid artery clamping and shunting in patients undergoing CEA under general anesthesia. With institutional approval and written informed consent, patients undergoing CEA under general anesthesia and routine carotid artery shunting were recorded bilaterally, simultaneously and continuously with an rSO2 and processed EEG monitor. The response of the monitors during carotid artery clamping and shunting were assessed and compared between monitors and bilaterally within each monitor. Sixty-nine patients were included in the study. At clamping the surgical-side and contralateral-side rSO2 dropped significantly below the baseline incision value (-17.6 and -9.4% respectively). After shunting, the contralateral-side rSO2 returned to baseline while the surgical-side rSO2 remained significantly below baseline (-9.0%) until the shunt was removed following surgery. At clamping the surgical-side and contralateral-side processed EEG also dropped below baseline (-19.9 and -20.6% respectively). However, following shunt activation, the processed EEG returned bilaterally to baseline. During the course of this research, we found the rSO2 monitor to be clinically more robust (4.4% failure rate) than the processed EEG monitor (20.0% failure rate). There was no correlation between the rSO2 or processed EEG changes that occurred immediately after clamping and the degree of surgical side stenosis measured pre-operatively. Both rSO2 and processed EEG respond to clamping and shunting during CEA. Cerebral oximetry discriminates between the surgical and contralateral side during surgery. The rSO2 monitor is more reliable in the real-world clinical setting. Future studies should focus on developing algorithms based on these

  12. Umbilical blood flow patterns directly after birth before delayed cord clamping.

    Science.gov (United States)

    Boere, I; Roest, A A W; Wallace, E; Ten Harkel, A D J; Haak, M C; Morley, C J; Hooper, S B; te Pas, A B

    2015-03-01

    Delayed umbilical cord clamping (DCC) affects the cardiopulmonary transition and blood volume in neonates immediately after birth. However, little is known of blood flow in the umbilical vessels immediately after birth during DCC. The objective is to describe the duration and patterns of blood flow through the umbilical vessels during DCC. Arterial and venous umbilical blood flow was measured during DCC using Doppler ultrasound in uncomplicated term vaginal deliveries. Immediately after birth, the probe was placed in the middle of the umbilical cord, pattern and duration of flow in vein and arteries were evaluated until cord clamping. Thirty infants were studied. Venous flow: In 10% no flow was present, in 57% flow stopped at 4:34 (3:03-7:31) (median (IQR) min:sec) after birth, before the cord was clamped. In 33%, flow continued until cord clamping at 5:13 (2:56-9:15) min:sec. Initially, venous flow was intermittent, increasing markedly during large breaths or stopping and reversing during crying, but then became continuous. Arterial flow: In 17% no flow was present, in 40% flow stopped at 4:22 (2:29-7:17) min:sec, while cord pulsations were still palpable. In 43% flow continued until the cord was clamped at 5:16 (3:32-10:10) min:sec. Arterial flow was pulsatile, unidirectional towards placenta or bidirectional to/from placenta. In 40% flow became continuous towards placenta later on. During delayed umbilical cord clamping, venous and arterial umbilical flow occurs for longer than previously described. Net placental transfusion is probably the result of several factors of which breathing could play a major role. Umbilical flow is unrelated to cessation of pulsations. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  13. Study and Effects of UPFC and its Control System for Power Flow Control and Voltage Injection in a Power System

    Directory of Open Access Journals (Sweden)

    Vibhor Gupta

    2010-07-01

    Full Text Available The maintenance and reliability of the power system has become a major aspect of study. The encouragement to the construction of HV lines, the amount of power transmission/km on HV line and the amount of power transaction as seen from economic side is much responsible for concern towards congestion in power system. The solution is the use of FACTS devices especially the use of UPFC. In this paper the study of UPFC with its various modes of operation is understood. Second, the operation of control system used in its converters is also studied. Finally by help of modeling of a power system in ATLAB, and by installing UPFC in transmission link, its use as power flow controller and voltage injection is seen. Conclusion is made ondifferent results to see the benefit of UPFC in power system.

  14. Interleaved soft-switched active-clamped L-L type current-fed half-bridge DC-DC converter for fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Rathore, Akshay K. [Electrical Machines and Drives Research Lab, University of Wuppertal, Rainer Gruenter Str. 21, University Campus Freudenberg, 42119 Wuppertal, NRW (Germany)

    2009-12-15

    In this paper, an interleaved soft-switched active-clamped L-L type current-fed half-bridge isolated dc-dc converter has been proposed. The L-L type active-clamped current-fed converter is able to maintain zero-voltage switching (ZVS) of all switches for the complete operating range of wide fuel cell stack voltage variation at full load down to light load conditions. Active-clamped circuit absorbs the turn-off voltage spike across the switches. Half-bridge topology maintains higher efficiency due to lower conduction losses. Soft-switching permits higher switching frequency operation, reducing the size, weight and cost of the magnetic components. Interleaving of the two isolated converters is done using parallel input series output approach and phase-shifted modulation is adopted. It reduces the input current ripple at the fuel cell input, which is required in a fuel cell system and also reduces the output voltage ripples. In addition, the size of the magnetic/passive components, current rating of the switches and voltage ratings of the rectifier diodes are reduced. (author)

  15. Clinical study on root canal therapy for calcified teeth with reciprocal instrument clamping K file%回旋手机夹持K型锉治疗钙化根管

    Institute of Scientific and Technical Information of China (English)

    何泽红; 程超; 金树人

    2015-01-01

    AIM:To evaluate the clinical outcome of reciprocal instrument clamping K file in the negotiation of calcified root canals. METHODS:167 calcified root canals of 112 teeth from 96 patients with pulpitis or apical periodontitis were negotiated with reciprocal instrument clamping K file and the outcome were evaluated. RESULTS:131(78. 44%) calci-fied root canals were successfully negotiated. Correlation was found between the success rate and tooth location, the success rate of the anterior teeth group was higher than that of the molar group (P<0. 05);the success rate of the canals with calci-fication of coronal to the bend position was significantly higher than that of apical to the bend position(P<0. 05). CON-CLUSION:The reciprocal instrument clamping K file is safe and effective in the treatment of calcified root canal, but it has certain limitation in negotiating the calcification of the root canals at apical to the bend position.%目的::评价回旋手机夹持K型锉疏通钙化根管的临床效果。方法:选择牙髓炎或根尖周炎患者96例112个患牙,共167个钙化根管,用回旋手机夹持K型锉进行疏通,评价根管疏通效果。结果:167个钙化根管,成功疏通131个(78.44%)。其中前牙组成功率高于磨牙组(P<0.05);钙化位于弯曲部位以上的成功率高于钙化位于弯曲部位以下的根管(P<0.05)。结论:回旋手机夹持K型锉疏通钙化根管安全、有效,但疏通钙化位于弯曲部位以下的根管方面尚有一定的局限性。

  16. Exploring Arterial Smooth Muscle Kv7 Potassium Channel Function using Patch Clamp Electrophysiology and Pressure Myography

    Science.gov (United States)

    Brueggemann, Lioubov I.; Mani, Bharath K.; Haick, Jennifer; Byron, Kenneth L.

    2012-01-01

    Contraction or relaxation of smooth muscle cells within the walls of resistance arteries determines the artery diameter and thereby controls flow of blood through the vessel and contributes to systemic blood pressure. The contraction process is regulated primarily by cytosolic calcium concentration ([Ca2+]cyt), which is in turn controlled by a variety of ion transporters and channels. Ion channels are common intermediates in signal transduction pathways activated by vasoactive hormones to effect vasoconstriction or vasodilation. And ion channels are often targeted by therapeutic agents either intentionally (e.g. calcium channel blockers used to induce vasodilation and lower blood pressure) or unintentionally (e.g. to induce unwanted cardiovascular side effects). Kv7 (KCNQ) voltage-activated potassium channels have recently been implicated as important physiological and therapeutic targets for regulation of smooth muscle contraction. To elucidate the specific roles of Kv7 channels in both physiological signal transduction and in the actions of therapeutic agents, we need to study how their activity is modulated at the cellular level as well as evaluate their contribution in the context of the intact artery. The rat mesenteric arteries provide a useful model system. The arteries can be easily dissected, cleaned of connective tissue, and used to prepare isolated arterial myocytes for patch clamp electrophysiology, or cannulated and pressurized for measurements of vasoconstrictor/vasodilator responses under relatively physiological conditions. Here we describe the methods used for both types of measurements and provide some examples of how the experimental design can be integrated to provide a clearer understanding of the roles of these ion channels in the regulation of vascular tone. PMID:23007713

  17. Committee Opinion No. 684: Delayed Umbilical Cord Clamping After Birth.

    Science.gov (United States)

    2017-01-01

    Delayed umbilical cord clamping appears to be beneficial for term and preterm infants. In term infants, delayed umbilical cord clamping increases hemoglobin levels at birth and improves iron stores in the first several months of life, which may have a favorable effect on developmental outcomes. There is a small increase in jaundice that requires phototherapy in this group of infants. Consequently, health care providers adopting delayed umbilical cord clamping in term infants should ensure that mechanisms are in place to monitor for and treat neonatal jaundice. In preterm infants, delayed umbilical cord clamping is associated with significant neonatal benefits, including improved transitional circulation, better establishment of red blood cell volume, decreased need for blood transfusion, and lower incidence of necrotizing enterocolitis and intraventricular hemorrhage. Delayed umbilical cord clamping was not associated with an increased risk of postpartum hemorrhage or increased blood loss at delivery, nor was it associated with a difference in postpartum hemoglobin levels or the need for blood transfusion. Given the benefits to most newborns and concordant with other professional organizations, the American College of Obstetricians and Gynecologists now recommends a delay in umbilical cord clamping in vigorous term and preterm infants for at least 30-60 seconds after birth. The ability to provide delayed umbilical cord clamping may vary among institutions and settings; decisions in those circumstances are best made by the team caring for the mother-infant dyad.

  18. Elevated neuronal excitability due to modulation of the voltage-gated sodium channel Nav1.6 by Aβ1-42

    Directory of Open Access Journals (Sweden)

    Xi eWang

    2016-03-01

    Full Text Available Aberrant increases in neuronal network excitability may contribute to the cognitive deficits in Alzheimer’s disease (AD. However, the mechanisms underlying hyperexcitability are not fully understood. Such overexcitation of neuronal networks has been detected in the brains of APP/PS1 mice. In the present study, using current-clamp recording techniques, we observed that 12 days in vitro (DIV primary cultured pyramidal neurons from P0 APP/PS1 mice exhibited a more prominent action potential burst and a lower threshold than WT littermates. Moreover, after treatment with Aβ1-42 peptide, 12 DIV primary cultured neurons showed similar changes, to a greater degree than in controls. Voltage-clamp recordings revealed that the voltage-dependent sodium current density of neurons incubated with Aβ1-42 was significantly increased, without change in the voltage-dependent sodium channel kinetic characteristics. Immunohistochemistry and western blot results showed that, after treatment with Aβ1-42, expressions of Nav and Nav1.6 subtype increased in cultured neurons or APP/PS1 brains compared to control groups. The intrinsic neuronal hyperexcitability of APP/PS1 mice might thus be due to an increased expression of voltage-dependent sodium channels induced by Aβ1-42. These results may illuminate the mechanism of aberrant neuronal networks in AD.

  19. Neutral Point Clamped Npc Type Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    Purohit Sadanand Chandrashekhar

    2015-08-01

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

  20. Conformational analysis of processivity clamps in solution demonstrates that tertiary structure does not correlate with protein dynamics.

    Science.gov (United States)

    Fang, Jing; Nevin, Philip; Kairys, Visvaldas; Venclovas, Ceslovas; Engen, John R; Beuning, Penny J

    2014-04-08

    The relationship between protein sequence, structure, and dynamics has been elusive. Here, we report a comprehensive analysis using an in-solution experimental approach to study how the conservation of tertiary structure correlates with protein dynamics. Hydrogen exchange measurements of eight processivity clamp proteins from different species revealed that, despite highly similar three-dimensional structures, clamp proteins display a wide range of dynamic behavior. Differences were apparent both for structurally similar domains within proteins and for corresponding domains of different proteins. Several of the clamps contained regions that underwent local unfolding with different half-lives. We also observed a conserved pattern of alternating dynamics of the α helices lining the inner pore of the clamps as well as a correlation between dynamics and the number of salt bridges in these α helices. Our observations reveal that tertiary structure and dynamics are not directly correlated and that primary structure plays an important role in dynamics.

  1. Deltamethrin Inhibits the Human T-type Voltage-Sensitive Calcium Channel (Cav3.2

    Directory of Open Access Journals (Sweden)

    Steven B. Symington

    2009-01-01

    Full Text Available The goal of this study was to determine the effect of deltamethrin, a pyrethroid insecticide, on CaV3.2, a human T-type voltage-sensitive calcium channel expressed in Xenopus laevis (X.laevis oocytes. Cav3.2 cDNA was transcribed into cRNA; the cRNA was then injected into X.laevis oocytes and electrophysiologically characterized using the two-electrode voltage clamp technique with Ba2+ as a charge carrier. Deltamethrin (10-7 M reduced peak current in a nonreversible manner compared to the untreated control, but had no effect on the voltagedependent activation and inactivation kinetics. These findings confirm that human CaV3.2 is a target for deltamethrin and quite possibly other pyrethroid insecticides. These studies provide insight into the molecular mechanisms of the effect that pyrethroids have on voltage-sensitive calcium channels in general. This information will allow a more complete understanding of the molecular and cellular nature of pyrethroid-induced toxicity and expand our knowledge of the structure-activity relationships of pyrethroids with regard to their action on voltage-sensitive calcium channels.

  2. Current umbilical cord clamping practices and attitudes of obstetricians and midwives toward delayed cord clamping in Saudi Arabia.

    Science.gov (United States)

    Ibrahim, Nadia O; Sukkarieh, Hatouf H; Bustami, Rami T; Alshammari, Elaf A; Alasmari, Lama Y; Al-Kadri, Hanan M

    2017-01-01

    In Saudi Arabia, as in many countries, there is usually no clear definition of the timing of umbilical cord clamping (UCC) in the policies and procedures used by hospitals. The World Health Organization (WHO) recommends delayed cord clamping (DCC) ( > 1 minute after birth) as it can significantly improve hemodynamics and long-term neurodevelopment. To investigate current practices of healthcare professionals on the timing of UCC in Saudi Arabia. Cross-sectional survey. Five tertiary hospitals in Riyadh, Saudi Arabia, during May to October 2016. Obstetricians and midwives completed a widely-used questionnaire on UCC practices. Current UCC practices and attitudes of obstetricians and midwives toward DCC. Eighty-two obstetricians and 75 midwives completed the questionnaire for a response rate of 80%. The majority of respondents were aged 30 years or older (81%) and 84% were females. Most respondents were non-Saudi (66%) and had an educational level of bachelor's degree or higher (72%). Only 42% of respondents reported the existence of UCC guidelines in their practice; 38% reported the existence of a set time for UCC when the neonate was term and healthy, and only 32% had a set time for UCC in preterm neonates. While lower levels of agreement were reported among obstetricians and midwives on the benefits of DCC for babies requiring positive pressure ventilation, the majority of respondents (69-71%) thought that DCC was generally good for both term and preterm babies and that its benefits extend beyond the neonatal period. While the majority of obstetricians and midwives that participated in this study had a positive perception toward DCC, this did not translate to their daily practice as most of these professionals reported a lack of existing UCC guidelines in their institutions. Further studies are warranted to confirm these findings. Participant selection by convenience sampling.

  3. Early vs delayed clamping of the umbilical cord in full term, preterm and very preterm infants

    DEFF Research Database (Denmark)

    Moller, N.K.; Weber, T.

    2008-01-01

    Randomized studies from 2006 and two meta-analyses published in 2007 agree that clamping of the umbilical cord can be delayed. For the preterm and very preterm infant benefits include less need for blood transfusion and less morbidity, especially for the very preterm male infant. For the term...

  4. Delayed cord clamping and haemoglobin levels in infancy : a randomised controlled trial in term babies

    NARCIS (Netherlands)

    van Rheenen, Patrick; de Moor, Lette; Eschbach, Sanne; de Grooth, Hannah; Brabin, Bernard

    Objectives This study was carried out to assess whether delaying umbilical cord clamping is effective in improving the haematological status of term infants living in a malaria-endemic area, and whether this is associated with complications in infants and mothers. Metyhods We randomly assigned women

  5. 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.

  6. 非线性负荷条件下的电压不平衡度探讨%Study on Voltage Unbalance Factor under Nonlinear Load

    Institute of Scientific and Technical Information of China (English)

    吕强; 徐晔; 王金全; 宋鹏超

    2013-01-01

    Damages caused by the unbalance of harmonic voltage in a low-voltage distribution system are discussed, the application principle of the symmetrical component method based on harmonics is analyzed; taking into account the regulations on voltage unbalance factor specified in national standard, the definition of the comprehensive unbalance factor of negative-sequence voltage and that of zero-sequence voltage are studied; the correctness of the theoretical analysis is proved by experiments; and the necessity of considering the unbalance of the harmonic voltage under nonlinear load is revealed through analysis.%阐述低压配电系统中谐波电压不平衡带来的危害,分析对称分量法在谐波条件下的应用原理;针对国家标准对电压不平衡度的规定,探讨负序电压综合不平衡度与零序电压综合不平衡度的定义;用实验证明理论分析的正确性;通过分析指出非线性负荷条件下考虑谐波电压不平衡的必要性。

  7. 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......-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...... 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...

  8. 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

    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......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......-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...

  9. High Power Neutral Point Clamped (NPC Multilevel UPFC with DC Link Switch for Effective Control of Real & Reactive Power

    Directory of Open Access Journals (Sweden)

    R Sanjay Kumar

    2016-01-01

    Full Text Available High-voltage and power capability of multilevel converters better used for unified power-flow controller (UPFC applications. The three-level neutral-point-clamped (NPC converter allows back-to-back connection as the UPFC shunt and series converters than other multilevel topologies. In place of the pulse width-modulated (PWM multilevel control schemes, constant dc-link voltage and balanced voltages in the NPC multilevel dc capacitors is necessary for UPFCs. The proposed work provides three main contributions to increase the performance of the system of multilevel UPFCs as this can be operated in STATCOM, SSSC and exactly in the UPFC mode with the double balancing of dc capacitor voltages under line faults, overall enhancing the UPFC ride-through capability. NPC series and shunt converters keep the dc-link voltage steady. Transients are the causes of fault in power system, Power System Stabilizer (PSS and Automatic Voltage Regulator (AVR are used to stabilize the response. The voltage regulator and current controller plays important roll to generate control pulses for VSC. A MATLAB simulation has been carried out to demonstrate the performance of the proposed model for UPFC in achieving transient stability with real and reactive power control.

  10. Voltage Management in Unbalanced Low Voltage Networks Using a Decoupled Phase-Tap-Changer Transformer

    DEFF Research Database (Denmark)

    Coppo, Massimiliano; Turri, Roberto; Marinelli, Mattia

    2014-01-01

    The paper studies a medium voltage-low voltage transformer with a decoupled on load tap changer capability on each phase. The overall objective is the evaluation of the potential benefits on a low voltage network of such possibility. A realistic Danish low voltage network is used for the analysis...

  11. The α2δ-1 subunit remodels CaV1.2 voltage sensors and allows Ca2+ influx at physiological membrane potentials

    Science.gov (United States)

    Pantazis, Antonios; Sigg, Daniel; Weiss, James N.; Neely, Alan

    2016-01-01

    Excitation-evoked calcium influx across cellular membranes is strictly controlled by voltage-gated calcium channels (CaV), which possess four distinct voltage-sensing domains (VSDs) that direct the opening of a central pore. The energetic interactions between the VSDs and the pore are critical for tuning the channel’s voltage dependence. The accessory α2δ-1 subunit is known to facilitate CaV1.2 voltage-dependent activation, but the underlying mechanism is unknown. In this study, using voltage clamp fluorometry, we track the activation of the four individual VSDs in a human L-type CaV1.2 channel consisting of α1C and β3 subunits. We find that, without α2δ-1, the channel complex displays a right-shifted voltage dependence such that currents mainly develop at nonphysiological membrane potentials because of very weak VSD–pore interactions. The presence of α2δ-1 facilitates channel activation by increasing the voltage sensitivity (i.e., the effective charge) of VSDs I–III. Moreover, the α2δ-1 subunit also makes VSDs I–III more efficient at opening the channel by increasing the coupling energy between VSDs II and III and the pore, thus allowing Ca influx within the range of physiological membrane potentials. PMID:27481713

  12. Analysis of the dynamic avalanche of carrier stored trench bipolar transistor (CSTBT) during clamped inductive turn-off transient

    Science.gov (United States)

    Xue, Peng; Fu, Guicui

    2017-03-01

    The dynamic avalanche has a huge impact on the switching robustness of carrier stored trench bipolar transistor (CSTBT). The purpose of this work is to investigate the CSTBT's dynamic avalanche mechanism during clamped inductive turn-off transient. At first, with a Mitsubishi 600 V/150 A CSTBT and a Infineon 600 V/200 A field stop insulated gate bipolar transistor (FS-IGBT) utilized, the clamped inductive turn-off characteristics are obtained by double pulse test. The unclamped inductive switching (UIS) test is also utilized to identify the CSTBT's clamping voltage under dynamic avalanche condition. After the test data analysis, it is found that the CSTBT's dynamic avalanche is abnormal and can be triggered under much looser condition than the conventional buffer layer IGBT. The comparison between the FS-IGBT and CSTBT's experimental results implies that the CSTBT's abnormal dynamic avalanche phenomenon may be induced by the carrier storage (CS) layer. Based on the semiconductor physics, the electric field distribution and dynamic avalanche generation in the depletion region are analyzed. The analysis confirms that the CS layer is the root cause of the CSTBT's abnormal dynamic avalanche mechanism. Moreover, the CSTBT's negative gate capacitance effect is also investigated to clarify the underlying mechanism of the gate voltage bump observed in the test. In the end, the mixed-mode numerical simulation is utilized to reproduce the CSTBT's dynamic avalanche behavior. The simulation results validate the proposed dynamic avalanche mechanisms.

  13. 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.

  14. A case study of voltage-gated potassium channel antibody-related limbic encephalitis with PET/MRI findings

    Directory of Open Access Journals (Sweden)

    Brian K. Day

    2015-01-01

    Full Text Available Preclinical and clinical studies have demonstrated the significance of inflammation and autoantibodies in epilepsy, and the use of immunotherapies in certain situations has become an established practice. Temporal lobe epilepsy can follow paraneoplastic or nonparaneoplastic limbic encephalitis associated with antibodies directed against brain antigens. Here, we focus on a patient with worsening confusion and temporal lobe seizures despite treatment with antiepileptic medications. Serial brain MRIs did not conclusively reveal structural abnormalities, so the patient underwent brain PET/MRI to simultaneously evaluate brain structure and function, revealing bitemporal abnormalities. The patient was diagnosed with voltage-gated potassium channel antibody-related limbic encephalitis based on clinical presentation, imaging findings, and antibody testing. Treatment included the addition of a second antiepileptic agent and oral steroids. His seizures and cognitive deficits improved and stabilized.

  15. Study of the Dependence on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

    Science.gov (United States)

    Bandler, Simon

    2011-01-01

    At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in the AC bias configuration. For x-ray photons at 6keV the AC biased pixel shows a best energy resolution of 3.7eV, which is about a factor of 2 worse than the energy resolution observed in identical DC-biased pixels. To better understand the reasons of this discrepancy, we investigated the detector performance as a function of temperature, bias working point and applied magnetic field. A strong periodic dependence of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recent weak-link behaviour observed inTES microcalorimeters.

  16. Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

    Science.gov (United States)

    Gottardi, L.; Bruijn, M.; denHartog, R.; Hoevers, H.; deKorte, P.; vanderKuur, J.; Linderman, M.; Adams, J.; Bailey, C.; Bandler, S.; Chervenak, J.; Eckart, M.; Finkbeiner, F.; Kelley, R.; Kilbourne, C.; Porter, F.; Sadlier, J.; Smith, S.

    2012-01-01

    At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution Delta E(sub FWHM) = 3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterized the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

  17. Measurement and analysis of postsynaptic potentials using a novel voltage-deconvolution method.

    Science.gov (United States)

    Richardson, Magnus J E; Silberberg, Gilad

    2008-02-01

    Accurate measurement of postsynaptic potential amplitudes is a central requirement for the quantification of synaptic strength, dynamics of short-term and long-term plasticity, and vesicle-release statistics. However, the intracellular voltage is a filtered version of the underlying synaptic signal and so a method of accounting for the distortion caused by overlapping postsynaptic potentials must be used. Here a voltage-deconvolution technique is demonstrated that defilters the entire voltage trace to reveal an underlying signal of well-separated synaptic events. These isolated events can be cropped out and reconvolved to yield a set of isolated postsynaptic potentials from which voltage amplitudes may be measured directly-greatly simplifying this common task. The method also has the significant advantage of providing a higher temporal resolution of the dynamics of the underlying synaptic signal. The versatility of the method is demonstrated by a variety of experimental examples, including excitatory and inhibitory connections to neurons with passive membranes and those with activated voltage-gated currents. The deconvolved current-clamp voltage has many features in common with voltage-clamp current measurements. These similarities are analyzed using cable theory and a multicompartment cell reconstruction, as well as direct comparison to voltage-clamp experiments.

  18. VOLTAGE-DEPENDENT SODIUM AND POTASSIUM, BUT NO CALCIUM CONDUCTANCES IN DDT1 MF-2 SMOOTH-MUSCLE CELLS

    NARCIS (Netherlands)

    MOLLEMAN, A; NELEMANS, A; VANDENAKKER, J; DUIN, M; DENHERTOG, A

    1991-01-01

    Voltage-dependent inward and outward membrane currents were investigated in the DDT1 MF-2 smooth muscle cell line using the whole-cell patch-clamp technique. Application of a pulse protocol with subsequent depolarizing voltage steps elicited an inactivating inward current and a non-inactivating outw

  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 topo...

  20. A clamp-like biohybrid catalyst for DNA oxidation

    Science.gov (United States)

    van Dongen, Stijn F. M.; Clerx, Joost; Nørgaard, Kasper; Bloemberg, Tom G.; Cornelissen, Jeroen J. L. M.; Trakselis, Michael A.; Nelson, Scott W.; Benkovic, Stephen J.; Rowan, Alan E.; Nolte, Roeland J. M.

    2013-11-01

    In processive catalysis, a catalyst binds to a substrate and remains bound as it performs several consecutive reactions, as exemplified by DNA polymerases. Processivity is essential in nature and is often mediated by a clamp-like structure that physically tethers the catalyst to its (polymeric) template. In the case of the bacteriophage T4 replisome, a dedicated clamp protein acts as a processivity mediator by encircling DNA and subsequently recruiting its polymerase. Here we use this DNA-binding protein to construct a biohybrid catalyst. Conjugation of the clamp protein to a chemical catalyst with sequence-specific oxidation behaviour formed a catalytic clamp that can be loaded onto a DNA plasmid. The catalytic activity of the biohybrid catalyst was visualized using a procedure based on an atomic force microscopy method that detects and spatially locates oxidized sites in DNA. Varying the experimental conditions enabled switching between processive and distributive catalysis and influencing the sliding direction of this rotaxane-like catalyst.

  1. The cardiovascular effects of aortic clamping and unclamping

    African Journals Online (AJOL)

    An increase in the slope of the Ea line represents an increase in ... increase. (for example as the subject exercises), stroke work ... aortic clamping is that afterload and blood pressure increase ..... nitroglycerine does not increase heart rate nor.

  2. Delay in Clamping Umbilical Cord Benefits Babies, Doctors Say

    Science.gov (United States)

    ... doctors' group said. Although delayed clamping increases the newborn's risk of jaundice that will require treatment, ACOG said there's no evidence that waiting increases the mother's risk of hemorrhage. The guidelines are to be published in the ...

  3. Recommendations for implementation of clamping strength in SteenToets: Kennisontwikkeling t.b.v. SteenToets 2006 Onderdeel 1 Normaalkracht

    NARCIS (Netherlands)

    Peters, D.J.

    2007-01-01

    This report belongs to the research programme on unknown aspects of Block Revetment systems. The stability of block revetments under wave loading is presumed to benefit from clamping forces. In previous studies a physical model for clamping forces was developed and verified. The existing design and

  4. Design, Control, and Modeling of a New Voltage Source Converter for HVDC System

    Science.gov (United States)

    Mohan, Madhan; Singh, Bhim; Ketan Panigrahi, Bijaya

    2013-05-01

    Abstract: A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (β), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.

  5. PROPERTIES OF VOLTAGE-GATED SODIUM CHANNELS IN DEVELOPING AUDITORY NEURONS OF THE MOUSE IN VITRO

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Objective. To investigate the properties of voltage-gated sodium (Na+) channels in developing auditoryneurons during early postnatal stages in the mammalian central nervous system.Methods. Using the whole-cell voltage-clamp technique, we have studied changes in the electrophysi-ological properties of Na+ channels in the principal neurons of the medial nucleus of the trapezoid body (MNTB).Results. We found that MNTB neurons already express functional Na+ channels at postnatal day 1 (P1),and that channel density begins to increase at P5 when the neurons receive synaptic innervation andreach its maximum (~3 fold) at P11 when functional hearing onsets. These changes were paralleled byan age-dependent acceleration in both inactivation and recovery from inactivation. In contrast, there wasvery little alteration in the voltage-dependence of inactivation.Conclusion. These profound changes in the properties of voltage-gated Na+ channels may increase theexcitability of MNTB neurons and enhance their phase-locking fidelity and capacity during high-frequencysynaptic transmission.

  6. 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.

  7. Eugenol dilates rat cerebral arteries by inhibiting smooth muscle cell voltage-dependent calcium channels.

    Science.gov (United States)

    Peixoto-Neves, Dieniffer; Leal-Cardoso, Jose Henrique; Jaggar, Jonathan H

    2014-11-01

    Plants high in eugenol, a phenylpropanoid compound, are used as folk medicines to alleviate diseases including hypertension. Eugenol has been demonstrated to relax conduit and ear arteries and reduce systemic blood pressure, but mechanisms involved are unclear. Here, we studied eugenol regulation of resistance-size cerebral arteries that control regional brain blood pressure and flow and investigated mechanisms involved. We demonstrate that eugenol dilates arteries constricted by either pressure or membrane depolarization (60 mM K) in a concentration-dependent manner. Experiments performed using patch-clamp electrophysiology demonstrated that eugenol inhibited voltage-dependent calcium (Ca) currents, when using Ba as a charge carrier, in isolated cerebral artery smooth muscle cells. Eugenol inhibition of voltage-dependent Ca currents involved pore block, a hyperpolarizing shift (∼-10 mV) in voltage-dependent inactivation, an increase in the proportion of steady-state inactivating current, and acceleration of inactivation rate. In summary, our data indicate that eugenol dilates cerebral arteries by means of multimodal inhibition of voltage-dependent Ca channels.

  8. Tetrahydroacridine inhibits voltage-dependent Na+ current in guinea-pig ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Wei WANG; Yi-ping WANG; Guo-yuan HU

    2004-01-01

    AIM: To study the effects of tetrahydroacridine (tacrine) on voltage-gated Na+ channels in cardiac tissues.METHODS: Single ventricular myocytes were enzymatically dissociated from adult guinea-pig heart. Voltagedependent Na+ current was recorded using whole cell voltage-clamp technique. RESULTS: (1) Tacrine reversibly inhibited Na+ current with an IC50 value of 120 μmol/L (95 % confidence range: 108-133 μmol/L). (2) The inhibitory effects of tacrine on Na+ current exhibited both a tonic nature and use-dependence. (3) Tacrine at 100 μmol/L caused a negative shift (about 10 mV) in the voltage-dependence of steady-state inactivation of Na+ current, and retarded its recovery from inactivation, but did not affect its activation curve. (4) Intracellular application of tacrine significantly inhibited Na+ current. CONCLUSION: In addition to blocking other voltage-gated ion channels,tacrine blocked Na+ channels in guinea-pig ventricular myocytes. Tactine acted as inactivation stabilizer of Na+channels in cardiac tissues.

  9. Effect of timing of umbilical cord clamping on iron status in Mexican infants: a randomised controlled trial.

    Science.gov (United States)

    Chaparro, Camila M; Neufeld, Lynnette M; Tena Alavez, Gilberto; Eguia-Líz Cedillo, Raúl; Dewey, Kathryn G

    2006-06-17

    Delayed clamping of the umbilical cord increases the infant's iron endowment at birth and haemoglobin concentration at 2 months of age. We aimed to assess whether a 2-minute delay in the clamping of the umbilical cord of normal-weight, full-term infants improved iron and haematological status up to 6 months of age. 476 mother-infant pairs were recruited at a large obstetrics hospital in Mexico City, Mexico, randomly assigned to delayed clamping (2 min after delivery of the infant's shoulders) or early clamping (around 10 s after delivery), and followed up until 6 months postpartum. Primary outcomes were infant haematological status and iron status at 6 months of age, and analysis was by intention-to-treat. This study is registered with ClinicalTrials.gov, number NCT00298051. 358 (75%) mother-infant pairs completed the trial. At 6 months of age, infants who had delayed clamping had significantly higher mean corpuscular volume (81.0 fL vs 79.5 fL 95% CI -2.5 to -0.6, p=0.001), ferritin (50.7 mug/L vs 34.4 mug/L 95% CI -30.7 to -1.9, p=0.0002), and total body iron. The effect of delayed clamping was significantly greater for infants born to mothers with low ferritin at delivery, breastfed infants not receiving iron-fortified milk or formula, and infants born with birthweight between 2500 g and 3000 g. A cord clamping delay of 2 minutes increased 6-month iron stores by about 27-47 mg. Delay in cord clamping of 2 minutes could help prevent iron deficiency from developing before 6 months of age, when iron-fortified complementary foods could be introduced.

  10. Choosing the wire clamp microdrive for termosonic microwelding equipments

    Directory of Open Access Journals (Sweden)

    Lanin V. L.

    2010-06-01

    Full Text Available The article describes research of three types of wire clamp microdrive for termosonic microwelding equipment, covering an expanded range microconductors from 12,5 up to 75 mm. The most preferable, in the light of their high-speed and easy-programming qualities, proved to be the mechanisms of conductor clamp with piezoelement drives and the loading system based on "voice-coil" type electromagnet.

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

    Science.gov (United States)

    Zinsser, Laura A

    2017-09-04

    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.

  12. 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......The voltage-gated Na(+) channels (Na(v)) form a family composed of 10 genes. The COOH termini of Na(v) contain a cluster of amino acids that are nearly identical among 7 of the 10 members. This COOH-terminal sequence, PPSYDSV, is a PY motif known to bind to WW domains of E3 protein...... 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....

  13. Predictive value of low tube voltage and dual-energy CT for successful shock wave lithotripsy: an in vitro study.

    Science.gov (United States)

    Largo, Remo; Stolzmann, Paul; Fankhauser, Christian D; Poyet, Cédric; Wolfsgruber, Pirmin; Sulser, Tullio; Alkadhi, Hatem; Winklhofer, Sebastian

    2016-06-01

    This study investigates the capabilities of low tube voltage computed tomography (CT) and dual-energy CT (DECT) for predicting successful shock wave lithotripsy (SWL) of urinary stones in vitro. A total of 33 urinary calculi (six different chemical compositions; mean size 6 ± 3 mm) were scanned using a dual-source CT machine with single- (120 kVp) and dual-energy settings (80/150, 100/150 Sn kVp) resulting in six different datasets. The attenuation (Hounsfield Units) of calculi was measured on single-energy CT images and the dual-energy indices (DEIs) were calculated from DECT acquisitions. Calculi underwent SWL and the number of shock waves for successful disintegration was recorded. The prediction of required shock waves regarding stone attenuation/DEI was calculated using regression analysis (adjusted for stone size and composition) and the correlation between CT attenuation/DEI and the number of shock waves was assessed for all datasets. The median number of shock waves for successful stone disintegration was 72 (interquartile range 30-361). CT attenuation/DEI of stones was a significant, independent predictor (P waves with the best prediction at 80 kVp (β estimate 0.576) (P waves ranged between ρ = 0.31 and 0.68 showing the best correlation at 80 kVp (P < 0.001). The attenuation of urinary stones at low tube voltage CT is the best predictor for successful stone disintegration, being independent of stone composition and size. DECT shows no added value for predicting the success of SWL.

  14. Whole-cell recordings of voltage-gated Calcium, Potassium and Sodium currents in acutely isolated hippocampal pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    Shuyun Huang; Qing Cai; Weitian Liu; Xiaoling Wang; Tao Wang

    2009-01-01

    Objective:To record Calcium, Potassium and Sodium currents in acutely isolated hippocampal pyramidal neurons. Methods:Hip-pocampal CA3 neurons were freshly isolated by 1 mg protease/3 ml SES and mechanical trituration with polished pipettes of progressively smaller tip diameters. Patch clamp technique in whole-cell mode was employed to record voltage-gated channel currents. Results:The procedure dissociated hippocampal neurons, preserving apical dendrites and several basal dendrites, without impairing the electrical characteristics of the neurons. Whole-cell patch clamp configuration was successfully used to record voltage-gated Ca2+ currents, delayed rectifier K+ current and voltage-gated Na+ currents. Conclusion:Protease combined with mechanical trituration may be used for the dissociation of neurons from rat hippocampus. Voltage-gated channels currents could be recorded using a patch clamp technique.

  15. Voltage Management in Unbalanced Low Voltage Networks Using a Decoupled Phase-Tap-Changer Transformer

    OpenAIRE

    Coppo, Massimiliano; Turri, Roberto; Marinelli, Mattia; Han, Xue

    2014-01-01

    The paper studies a medium voltage-low voltage transformer with a decoupled on load tap changer capability on each phase. The overall objective is the evaluation of the potential benefits on a low voltage network of such possibility. A realistic Danish low voltage network is used for the analysis. The load profiles are characterized by using single phase measurement data on voltages, currents and active powers with a 10 minutes resolution. Different scenarios are considered: no tap action, th...

  16. Influence of phenylephrine or ephedrine on maternal hemodynamics upon umbilical cord clamping during cesarean delivery.

    Science.gov (United States)

    Quan, Zhefeng; Tian, Ming; Chi, Ping; Cao, Yinghao; Li, Xin; Peng, Kejun

    2013-11-01

    Vasopressors ephedrine and phenylephrine are commonly used with spinal anesthesia during cesarean delivery. Studies on them have focused on the period before the umbilical cord is clamped, although anesthesia is continuously administered throughout and after this event. This study aimed to compare the effects of these drugs on maternal hemodynamics at and after clamping of the umbilical cord. Prospective, randomized, double-blind study. Parturients (n = 60) scheduled for elective cesarean delivery were randomly divided into an ephedrine group and a phenylephrine group. Each woman received an intrathecal injection of bupivacaine (7.5 mg). Patients in the ephedrine and phenylephrine groups were infused continuously with ephedrine (0.02 mg×kg-1×min-1) or phenylephrine (0.25 μg×kg-1×min-1), respectively, from immediately after the injection of bupivacaine until termination 10 minutes after the umbilical cord was clamped (the endpoint). Hemodynamic changes were recorded. After clamping the umbilical cord, the patients who were administered ephedrine experienced significant increases in heart rate (89 ± 11 beats/min to 106 ± 15 beats/min), cardiac output (6.4 ± 0.9 l/min to 7.6 ± 1.2 l/min) and cardiac index (3.5 ± 0.39 l×min-1×m-2 to 4.3 ± 0.48 l×min-1×m-2), while the systemic vascular resistance decreased (908 ± 296 dyne·s/cm5 to 711 ± 285 dyne·s/cm5). Such differences were not observed in the patients who received phenylephrine. Moreover, the heart rate of patients administered ephedrine was higher than that of patients given phenylephrine after clamping the umbilical cord. Continuous infusion of phenylephrine during cesarean delivery maintains a stable maternal hemodynamic status better than ephedrine.

  17. Study of metal transfer process in MIG / MAG through the fractal dimension of the signal voltage

    OpenAIRE

    Josà Carlos de Souza Carneiro

    2005-01-01

    The techniques for estimating the fractal dimension of signals have been widely applied in the description of many physical systems, from studies of atmospheric turbulence, EEG signals, water systems to studies on the behavior of fractal surfaces fractured by impact. The analysis of the fractal dimension of complex phenomena has become an important tool to quantify the degree of irregularity of artificial or natural phenomena. In this paper we investigate the fractal dimension of the signa...

  18. Current–voltage studies on -FeSi2/Si heterojunction

    Indian Academy of Sciences (India)

    A Datta; S Kal; S Basu

    2000-08-01

    – characteristics of both -FeSi2/n-Si and -FeSi2/p-Si were studied at room temperature. The junctions were formed by depositing Fe on Si selectively followed by thermal annealing and some samples were later treated by pulsed laser. Temperature of thermal annealing and diode area were also varied. – studies on all these samples were done and ideality factors were computed. Results obtained were interpreted.

  19. Study of SEM induced current and voltage contrast modes to assess semiconductor reliability

    Science.gov (United States)

    Beall, J. R.

    1976-01-01

    The purpose of the scanning electron microscopy study was to review the failure history of existing integrated circuit technologies to identify predominant failure mechanisms, and to evaluate the feasibility of their detection using SEM application techniques. The study investigated the effects of E-beam irradiation damage and contamination deposition rates; developed the necessary methods for applying the techniques to the detection of latent defects and weaknesses in integrated circuits; and made recommendations for applying the techniques.

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

    Science.gov (United States)

    Polglase, Graeme R; Dawson, Jennifer A; Kluckow, Martin; Gill, Andrew W; Davis, Peter G; Te Pas, Arjan B; Crossley, Kelly J; McDougall, Annie; Wallace, Euan M; Hooper, Stuart B

    2015-01-01

    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.

  1. 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.

  2. Study on automatic voltage regulation technology of rural power grids%农村电网自动稳压技术的研究

    Institute of Scientific and Technical Information of China (English)

    孙猛; 赵玉林; 付岩

    2012-01-01

    经技术改造,农网电压质量有所提高,但波动范围仍然超出国家规定允许值,制约农村经济的发展.文章研究一种基于固态继电器的采用对农网配变电压器调压绕组正反串联,实现稳定农村电网电压目的的无触点有栽调压分接开关的接线及其控制方式.理论分析与模拟实验表明,这种稳压技术具有调压范围大,元件实际承受电压低,结构简单的优点,适用于农村电网.%Through technical reconstruction, the rural power grid voltage quality has been improved. But the voltage fluctuation range is still lager than the allowable value of national regulation. This situation seriously restricts the development of rural economy. This paper studied a non-contact on-load voltage regulation tap changer wiring and its control method. Used the way of connecting the regulating windings of distribution transformer positive and negative to achieve the goal of stabilizing the voltage of rural power grids. Theory analysis and simulation experiment manifested that this stabilizing voltage technology had advantages of large voltage regulating range, low actual beard voltage of elements and simple structure. And this technology was suitable for rural power grid.

  3. Whole-cell clamp of dissociated photoreceptors from the eye of Lima scabra.

    Science.gov (United States)

    Nasi, E

    1991-01-01

    Voltage-dependent membrane currents were investigated in enzymatically dissociated photoreceptors of Lima scabra using the whole-cell clamp technique. Depolarizing steps to voltages more positive than -10 mV elicit a transient inward current followed by a delayed, sustained outward current. The outward current is insensitive to replacement of a large fraction of extracellular Cl- with the impermeant anion glucuronate. Superfusion with tetraethylammonium and 4-aminopyridine reversibly abolishes the outward current, and internal perfusion with cesium also suppresses it, indicating that it is mediated by potassium channels. Isolation of the inward current reveals a fast activation kinetics, the peak amplitude occurring as early as 4-5 ms after stimulus onset, and a relatively rapid, though incomplete inactivation. Within the range of voltages examined, spanning up to +90 mV, reversal was not observed. The inward current is not sensitive to tetrodotoxin at concentrations up to 10 microM, and survives replacement of extracellular Na with tetramethylammonium. On the other hand, it is completely eliminated by calcium removal from the perfusing solution, and it is partially blocked by submillimolar concentrations of cadmium, suggesting that it is entirely due to voltage-dependent calcium channels. Analysis of the kinetics and voltage dependence of the isolated calcium current indicates the presence of two components, possibly reflecting the existence of separate populations of channels. Barium and strontium can pass through these channels, though less easily than calcium. Both the activation and the inactivation become significantly more sluggish when these ions serve as the charge carrier. A large fraction of the outward current is activated by preceding calcium influx. Suppression of this calcium-dependent potassium current shows a small residual component resembling the delayed rectifier. In addition, a transient outward current sensitive to 4-aminopyridine (Ia) could

  4. 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.

  5. Computer simulation and experimental study of transient processes in a single-phase voltage transformer

    Science.gov (United States)

    Kruzhaev, A. V.; Elagin, I. A.; Pavleino, M. A.; Dmitriev, V. A.; Chaly, A. M.

    2015-02-01

    We perform simulation and experimental investigation of transient processes emerging in a single-phase transformer when it is connected to the network. The transformer model constructed taking into account the saturation of the steel of the core differs from standard models in detailed accounting for the magnetic flux leakage, which is required, for example, for a correct description of inrush current. Universality of the model for the type of transformers under study is ensured by the allowance for eddy current losses and calculation of the magnetic hysteresis in the steel core. The latter makes it possible to estimate the effect of residual magnetization of the core on the form of a transient process, which is studied in detail. The methods for computing model parameters are described and its experimental verification is carried out.

  6. The Analysis of Clamping Mechanism Theory and the Application Design of Tobacco Leaves'Clamping Tool%夹紧机构的理论分析及烘烤烟叶夹的应用设计

    Institute of Scientific and Technical Information of China (English)

    徐远龙; 孙有祥

    2011-01-01

    In view of the complicated manual skill of the tobacco leaf weaving, the study and design of a kind tool clamping tobacco leaf is proposed by our actual investigation; According to the predetermined function demand and the available clamping mechanism, the principle of the clamping tool is studied out, the structural design scheme of the clamping tool is worked out and the clamping tool is made by the theory analysis of mechanism design and the study of clamping mechanism. The clamping tool tested by the surveyor is good in use, which is welcome to use by the peasants and the economy benefit of the market can be achieved highly.%通过对烟叶烘烤生产工艺的实际调研,针对手工繁杂的编烟技术,提出了研究设计一种烘烤烟叶夹持工具;针对烘烤烟叶夹的预定功能要求,参考现有的实用夹紧机构,通过对机械产品机构设计的理论分析和夹紧机构的力学研究,确定了夹紧烟叶的力学原理,提出了烘烤烟叶夹的结构设计方案,设计制造出烘烤烟叶夹;该烘烤烟叶夹通过了产品的质量检测,使用效果良好,烟农用户普遍接受使用,预计有较高的市场经济效益.

  7. Biological and Agricultural Studies on Application of Discharge Plasma and Electromagnetic Fields 4. Destruction of Weeds by High Voltage Discharge

    Science.gov (United States)

    Mizuno, Akira

    In an attempt to replace chemicals for weed control, high voltage spark discharge has been applied. With the application of high voltage, discharge takes place, and current flows through the stem and root. Microscopic observation indicates that cells are damaged. The electrical resistance of the damage plant’s stems and roots decreased significantly. Several different types of apparatus were constructed, and field test results show the effectiveness of electrical discharge for weed control.

  8. Study on Factors for Accurate Open Circuit Voltage Characterizations in Mn-Type Li-Ion Batteries

    OpenAIRE

    Natthawuth Somakettarin; Tsuyoshi Funaki

    2017-01-01

    Open circuit voltage (OCV) of lithium batteries has been of interest since the battery management system (BMS) requires an accurate knowledge of the voltage characteristics of any Li-ion batteries. This article presents an OCV characteristic for lithium manganese oxide (LMO) batteries under several experimental operating conditions, and discusses factors for accurate OCV determination. A test system is developed for OCV characterization based on the OCV pulse test method. Various factors for ...

  9. Ventilation before Umbilical Cord Clamping Improves the Physiological Transition at Birth.

    Science.gov (United States)

    Bhatt, Sasmira; Polglase, Graeme R; Wallace, Euan M; Te Pas, Arjan B; Hooper, Stuart B

    2014-01-01

    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 labor. 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 previously have 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 labor. 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.

  10. 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.

  11. Assessment of surge arrester failure rate and application studies in Hellenic high voltage transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Christodoulou, C.A.; Fotis, G.P.; Gonos, I.F.; Stathopulos, I.A. [National Technical University of Athens, School of Electrical and Computer Engineering, High Voltage Laboratory, 9 Iroon Politechniou St., Zografou Campus, 157 80 Athens (Greece); Ekonomou, L. [A.S.PE.T.E. - School of Pedagogical and Technological Education, Department of Electrical Engineering Educators, N. Heraklion, 141 21 Athens (Greece)

    2010-02-15

    The use of transmission line surge arresters to improve the lightning performance of transmission lines is becoming more common. Especially in areas with high soil resistivity and ground flash density, surge arresters constitute the most effective protection mean. In this paper a methodology for assessing the surge arrester failure rate based on the electrogeometrical model is presented. Critical currents that exceed arresters rated energy stress were estimated by the use of a simulation tool. The methodology is applied on operating Hellenic transmission lines of 150 kV. Several case studies are analyzed by installing surge arresters on different intervals, in relation to the region's tower footing resistance and the ground flash density. The obtained results are compared with real records of outage rate showing the effectiveness of the surge arresters in the reduction of the recorded failure rate. The presented methodology can be proved valuable to the studies of electric power systems designers intending in a more effective lightning protection, reducing the operational costs and providing continuity of service. (author)

  12. [Spectroscopic study on the high voltage fast pulsed discharge of nitrogen, ammonia or their mixture].

    Science.gov (United States)

    Liu, Z P; Wang, P N; Yang, W D; Zheng, J B; Li, F M

    2001-10-01

    The emission spectra from the pulsed discharge plasma of nitrogen, ammonia or their mixture were measured. In the discharge of pure nitrogen gas, as the pressure increased, the discharge volume decreased and more dissociation of nitrogen molecules occurred due to the higher energy density. In the discharge of ammonia, N,N+ and NH+ were observed, but no NH2 and NH3 were detected, indicating that ammonia, which has the lower dissociation and ionization energies as compared to nitrogen, was highly dissociated. The discharge of the mixture of N2 and NH3 was also studied. The dependence of the dissociation of nitrogen on the ratio of nitrogen to ammonia was investigated by emission spectra. The optimal ratio for nitrogen dissociation was obtained. The advantage of using the mixture of nitrogen and ammonia in the synthesis of nitrides was discussed.

  13. Comparative Study of Fault Diagnostic Methods in Voltage Source Inverter Fed Three Phase Induction Motor Drive

    Science.gov (United States)

    Dhumale, R. B.; Lokhande, S. D.

    2017-05-01

    Three phase Pulse Width Modulation inverter plays vital role in industrial applications. The performance of inverter demeans as several types of faults take place in it. The widely used switching devices in power electronics are Insulated Gate Bipolar Transistors (IGBTs) and Metal Oxide Field Effect Transistors (MOSFET). The IGBTs faults are broadly classified as base or collector open circuit fault, misfiring fault and short circuit fault. To develop consistency and performance of inverter, knowledge of fault mode is extremely important. This paper presents the comparative study of IGBTs fault diagnosis. Experimental set up is implemented for data acquisition under various faulty and healthy conditions. Recent methods are executed using MATLAB-Simulink and compared using key parameters like average accuracy, fault detection time, implementation efforts, threshold dependency, and detection parameter, resistivity against noise and load dependency.

  14. 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.

  15. Dynamic simulation and experimental study of inspection robot for high-voltage transmission-line

    Institute of Scientific and Technical Information of China (English)

    XIAO Xiao-hui; WU Gong-ping; DU E; SHI Tie-lin

    2005-01-01

    A mobile robot developed by Wuhan University for full-path hotline inspection on 220 kV transmission lines was presented. With 4 rotating joints and 2 translational ones, such robot is capable of traveling along non-obstacle straight-line segment and surmounting straight-line segment obstacles as well as transferring between two spans automatically. Lagrange's equations were utilized to derive dynamic equations of all the links, including items of inertia, coupling inertia, Coriolis acceleration, centripetal acceleration and gravity. And a dynamic response experiment on elemental motions of robot prototype's travelling along non-obstacle straight-line segment and surmounting obstacles was performed on 220 kV 1∶1 simulative overhanging transmission-line in laboratory. In addition, dynamic numerical simulation was conducted in the corresponding condition. Comparison and analysis on results of experiment and numerical simulation have validated theoretical model and simulation resolution. Therefore, the dynamic model formed hereunder can be used for the study of robot control.

  16. A Test Study of 50% Lightning Impulse Breakdown Voltage on Rod-Plane Gap with Two-Phase Mixture of Gas and Solid Particles

    Institute of Scientific and Technical Information of China (English)

    HE Zheng-hao; XU Huai-li; BAI Jing; YU Fu-sheng; HU Feng; LI Jin

    2007-01-01

    A test study on 50% lightning impulse breakdown voltage in two-phase mixture of gas and solid particles has been carried out in a specially designed discharge cabinet.A mechanical sieve is set up for sifting different solid particles into the discharge space uniformly.The lightning impulse voltage according with international electro-technical commission (IEC) standard is applied to the electrodes inside the discharge cabinet by the rule of up-down method in a total of 40 times.The results showed that the 50% lightning impulse breakdown voltage in two-phase mixture of gas and solid particles has its own features and is much different from that in air.

  17. Novel Full-bridge ZVS DC-DC Converter with an Clamp Diodes

    Science.gov (United States)

    Guangqun, Nan; Xue, Hu

    The two arms of this converter all work at zero-voltage switching condition, that bring many advantages, such as little loss of power, simple control, etc. But these also exists some problems, such as parasitic oscillation on the output rectifier diodes. A novel full-bridge ZVS PWM DC-DC converter which adopts two clamping diodes in the first side of the transformer is proposed to reduce the parasitic oscillation in this paper. In this paper, It heavily analyzes the realization process of their soft-switching and the reason of related issues and solution, we establishes simulation model and simulates using orCAD. Finally,a 5 kW ZVS PWM DC-DC converter Prototype in that TMS320F2812 is the core controlled chip has been set up, and the experiments showed us the validation of the correlative theory.

  18. Harmonic Mitigated Front End Three Level Diode Clamped High Frequency Link Inverter by Using MCI Technique

    Directory of Open Access Journals (Sweden)

    Sreedhar Madichetty

    2014-02-01

    Full Text Available In this paper it proposes a high efficient soft-switching scheme based on zero-voltage-switching (ZVS and zero-current-switching(ZCS principle operated with a simple auxiliary circuit extended range for the front-end isolated DC-AC-DC-AC high power converter with an three phase three level diode clamped multi level inverter by using Minority Charge Carrier inspired optimization technique (MCI with Total Harmonic Distortion(THD,Switching losses, Selective harmonic elimination maintaining with its fundamental as an objective function. Input to the inverter is obtained by the photo voltaic cells and with battery bank. The switching scheme is optimized by MCI technique, analyzed and executed in Matlab and implemented with a digital signal processor (DSP .Experimental results with different loads have observed and shows its effectives, robustness of the applied technique.

  19. 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.

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

    Directory of Open Access Journals (Sweden)

    C. H. Chang

    2013-03-01

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

  1. 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...

  2. 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

    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...... that have been presented. The presented strategies are also comparatively evaluated to identify their individual advantages and disadvantages, which are subsequently summarized in a comprehensive reference table. Last, simulation and experimental results are included for validating the performances...

  3. Model Predictive Control of Z-source Neutral Point Clamped Inverter

    DEFF Research Database (Denmark)

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

    2011-01-01

    This paper presents Model Predictive Control (MPC) of Z-source Neutral Point Clamped (NPC) inverter. For illustration, current control of Z-source NPC grid-connected inverter is analyzed and simulated. With MPC’s advantage of easily including system constraints, load current, impedance network...... inductor current, capacitor voltage as well as switching frequency, transient response are all regulated as subjecting to constraints of this control method. The quality of output waveform, stability of impedance-network, level constraint of variable switching frequency as well as robustness of transient...... response are obtained at the same time with a formulated Z-source NPC inverter network model. Operation steady state and transient state simulation results of MPC are going to be presented, which shows good reference tracking ability of this method. It provides new control method for Z-source NPC inverter...

  4. Transient Voltage Recorder

    Science.gov (United States)

    Medelius, Pedro J. (Inventor); Simpson, Howard J. (Inventor)

    2002-01-01

    A voltage transient recorder can detect lightning induced transient voltages. The recorder detects a lightning induced transient voltage and adjusts input amplifiers to accurately record transient voltage magnitudes. The recorder stores voltage data from numerous monitored channels, or devices. The data is time stamped and can be output in real time, or stored for later retrieval. The transient recorder, in one embodiment, includes an analog-to-digital converter and a voltage threshold detector. When an input voltage exceeds a pre-determined voltage threshold, the recorder stores the incoming voltage magnitude and time of arrival. The recorder also determines if its input amplifier circuits clip the incoming signal or if the incoming signal is too low. If the input data is clipped or too low, the recorder adjusts the gain of the amplifier circuits to accurately acquire subsequent components of the lightning induced transients.

  5. A randomized clinical trial comparing immediate versus delayed clamping of the umbilical cord in preterm infants: short-term clinical and laboratory endpoints.

    Science.gov (United States)

    Strauss, Ronald G; Mock, Donald M; Johnson, Karen J; Cress, Gretchen A; Burmeister, Leon F; Zimmerman, M Bridget; Bell, Edward F; Rijhsinghani, Asha

    2008-04-01

    Most neonates less than 1.0 kg birth weight need red blood cell (RBC) transfusions. Delayed clamping of the umbilical cord 1 minute after delivery transfuses the neonate with autologous placental blood to expand blood volume and provide 60 percent more RBCs than after immediate clamping. This study compared hematologic and clinical effects of delayed versus immediate cord clamping. After parental consent, neonates not more than 36 weeks' gestation were randomly assigned to cord clamping immediately or at 1 minute after delivery. The primary endpoint was an increase in RBC volume/mass, per biotin labeling, after delayed clamping. Secondary endpoints were multiple clinical and laboratory comparisons over the first 28 days including Score for Neonatal Acute Physiology (SNAP). Problems with delayed clamping techniques prevented study of neonates of less than 30 weeks' gestation, and 105 neonates 30 to 36 weeks are reported. Circulating RBC volume/mass increased (p = 0.04) and weekly hematocrit (Hct) values were higher (p clamping. Higher Hct values did not lead to fewer RBC transfusions (p > or = 0.70). Apgar scores after birth and daily SNAP scores were not significantly different (p > or = 0.22). Requirements for mechanical ventilation with oxygen were similar. More (p = 0.03) neonates needed phototherapy after delayed clamping, but initial bilirubin levels and extent of phototherapy did not differ. Although a 1-minute delay in cord clamping significantly increased RBC volume/mass and Hct, clinical benefits were modest. Clinically significant adverse effects were not detected. Consider a 1-minute delay in cord clamping to increase RBC volume/mass and RBC iron, for neonates 30 to 36 weeks' gestation, who do not need immediate resuscitation.

  6. Childhood cancer and magnetic fields from high-voltage power lines in England and Wales: a case–control study

    Science.gov (United States)

    Kroll, M E; Swanson, J; Vincent, T J; Draper, G J

    2010-01-01

    Background: Epidemiological evidence suggests that chronic low-intensity extremely-low-frequency magnetic-field exposure is associated with increased risk of childhood leukaemia; it is not certain the association is causal. Methods: We report a national case–control study relating childhood cancer risk to the average magnetic field from high-voltage overhead power lines at the child's home address at birth during the year of birth, estimated using National Grid records. From the National Registry of Childhood Tumours, we obtained records of 28 968 children born in England and Wales during 1962–1995 and diagnosed in Britain under age 15. We selected controls from birth registers, matching individually by sex, period of birth, and birth registration district. No participation by cases or controls was required. Results: The estimated relative risk for each 0.2 μT increase in magnetic field was 1.14 (95% confidence interval 0.57 to 2.32) for leukaemia, 0.80 (0.43–1.51) for CNS/brain tumours, and 1.34 (0.84–2.15) for other cancers. Conclusion: Although not statistically significant, the estimate for childhood leukaemia resembles results of comparable studies. Assuming causality, the estimated attributable risk is below one case per year. Magnetic-field exposure during the year of birth is unlikely to be the whole cause of the association with distance from overhead power lines that we previously reported. PMID:20877338

  7. PIP2 in pancreatic β-cells regulates voltage-gated calcium channels by a voltage-independent pathway.

    Science.gov (United States)

    de la Cruz, Lizbeth; Puente, Erika I; Reyes-Vaca, Arturo; Arenas, Isabel; Garduño, Julieta; Bravo-Martínez, Jorge; Garcia, David E

    2016-10-01

    Phosphatidylinositol-4,5-bisphosphate (PIP2) is a membrane phosphoinositide that regulates the activity of many ion channels. Influx of calcium primarily through voltage-gated calcium (CaV) channels promotes insulin secretion in pancreatic β-cells. However, whether CaV channels are regulated by PIP2, as is the case for some non-insulin-secreting cells, is unknown. The purpose of this study was to investigate whether CaV channels are regulated by PIP2 depletion in pancreatic β-cells through activation of a muscarinic pathway induced by oxotremorine methiodide (Oxo-M). CaV channel currents were recorded by the patch-clamp technique. The CaV current amplitude was reduced by activation of the muscarinic receptor 1 (M1R) in the absence of kinetic changes. The Oxo-M-induced inhibition exhibited the hallmarks of voltage-independent regulation and did not involve PKC activation. A small fraction of the Oxo-M-induced CaV inhibition was diminished by a high concentration of Ca(2+) chelator, whereas ≥50% of this inhibition was prevented by diC8-PIP2 dialysis. Localization of PIP2 in the plasma membrane was examined by transfecting INS-1 cells with PH-PLCδ1, which revealed a close temporal association between PIP2 hydrolysis and CaV channel inhibition. Furthermore, the depletion of PIP2 by a voltage-sensitive phosphatase reduced CaV currents in a way similar to that observed following M1R activation. These results indicate that activation of the M1R pathway inhibits the CaV channel via PIP2 depletion by a Ca(2+)-dependent mechanism in pancreatic β- and INS-1 cells and thereby support the hypothesis that membrane phospholipids regulate ion channel activity by interacting with ion channels.

  8. Screening fluorescent voltage indicators with spontaneously spiking HEK cells.

    Directory of Open Access Journals (Sweden)

    Jeehae Park

    Full Text Available Development of improved fluorescent voltage indicators is a key challenge in neuroscience, but progress has been hampered by the low throughput of patch-clamp characterization. We introduce a line of non-fluorescent HEK cells that stably express NaV 1.3 and KIR 2.1 and generate spontaneous electrical action potentials. These cells enable rapid, electrode-free screening of speed and sensitivity of voltage sensitive dyes or fluorescent proteins on a standard fluorescence microscope. We screened a small library of mutants of archaerhodopsin 3 (Arch in spiking HEK cells and identified two mutants with greater voltage-sensitivity than found in previously published Arch voltage indicators.

  9. Effect of delayed cord clamping on very preterm infants.

    Science.gov (United States)

    Chiruvolu, Arpitha; Tolia, Veeral N; Qin, Huanying; Stone, Genna Leal; Rich, Diana; Conant, Rhoda J; Inzer, Robert W

    2015-11-01

    Despite significant proposed benefits, delayed umbilical cord clamping (DCC) is not practiced widely in preterm infants largely because of the question of feasibility of the procedure and uncertainty regarding the magnitude of the reported benefits, especially intraventricular hemorrhage (IVH) vs the adverse consequences of delaying the neonatal resuscitation. The objective of this study was to determine whether implementation of the protocol-driven DCC process in our institution would reduce the incidence of IVH in very preterm infants without adverse consequences. We implemented a quality improvement process for DCC the started in August 2013 in infants born at ≤32 weeks' gestational age. Eligible infants were left attached to the placenta for 45 seconds after birth. Neonatal process and outcome data were collected until discharge. We compared infants who received DCC who were born between August 2013 and August 2014 with a historic cohort of infants who were born between August 2012 and August 2013, who were eligible to receive DCC, but whose cord was clamped immediately after birth, because they were born before the protocol implementation. DCC was performed on all the 60 eligible infants; 88 infants were identified as historic control subjects. Gestational age, birthweight, and other demographic variables were similar between both groups. There were no differences in Apgar scores or admission temperature, but significantly fewer infants in the DCC cohort were intubated in delivery room, had respiratory distress syndrome, or received red blood cell transfusions in the first week of life compared with the historic cohort. A significant reduction was noted in the incidence of IVH in the DCC cohort compared with the historic control group (18.3% vs 35.2%). After adjustment for gestational age, an association was found between the incidence of IVH and DCC with IVH was significantly lower in the DCC cohort compared with the historic cohort; an odds ratio of 0

  10. A Study of the Effect of Gold Thickness Distribution in the Jet Plating Process to Optimize Gold Usage and Plating Voltage Using Design of Experiments

    Directory of Open Access Journals (Sweden)

    Aramphongphun Chuckaphun

    2016-01-01

    Full Text Available A gold plating process in the electronics industry can be classified as (i all surface plating or (ii selective plating. Selective plating is more widely used than all surface plating because it can save more gold used in the plating process and takes less plating time. In this research, the selective plating process called jet plating was studied. Factors that possibly affected the gold usage and plating voltage were also studied to reduce the production cost. These factors included (a plating temperature, (b crystal (inhibitor amount, (c distance between workpiece and anode, (d plating current and (e plating speed. A two-level Full Factorial design with center points was first performed to screen the factors. A Central Composite Design (CCD was then employed to optimize the factors in jet plating. The amount of gold usage should be reduced to 0.366 g / 10,000 pieces, the plating speed should be increased to 4 m/min and the plating voltage should not exceed 8.0 V. According to the analysis, the optimal settings should be as follows: the plating temperature at 55.5 deg C, the crystal amount at 90%, the distance at 0.5 mm, the plating current at 2.8 A, and the plating speed at 4.5 m/min. This optimal setting led to gold usage of 0.350 g / 10,000 pieces and a plating voltage of 7.16 V. Confirmation runs of 30 experiments at the optimal conditions were then performed. It was found that the gold usage and the plating voltage of the confirmation runs were not different from the optimized gold usage and plating voltage. The optimal condition was then applied in production, which could reduce the gold usage by 4.5% and increase the plating speed by 12.5% while the plating voltage did not exceed the limit.

  11. 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.

  12. 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.

  13. Effects of in vitro lead exposure on voltage-sensitive calcium channels differ among cell types in central neurons of Lymnaea stagnalis.

    Science.gov (United States)

    Audesirk, G; Audesirk, T

    1989-01-01

    The effects of acute in vitro lead exposure on slowly inactivating voltage-sensitive calcium channels in central neurons of the freshwater pond snail Lymnaea stagnalis were studied under voltage clamp. Three physiologically distinct cell types were used: two subsets of the B cell cluster (Bpos and Bneg) and the pedal giant neuron (RPeD1). In Bpos neurons, 5 nM free Pb2+ irreversibly inhibited current flow through calcium channels by 38 +/- 10%. In Bneg neurons, 5 nM free Pb2+ slightly inhibited inward currents (12 +/- 6%) and may have shifted their voltage dependence to more depolarized voltages. The inhibition and voltage shift were irreversible. In RPeD1 neurons, Pb2+ caused a small, statistically insignificant inhibition of inward current (5 nM free Pb2+; 18 +/- 19%; 30 nM free Pb2+: 31 +/- 23%). The effects of Pb2+ were fully reversible. These data indicate that (1) voltage-sensitive calcium channels in Lymnaea neurons are inhibited by nanomolar concentrations of free Pb2+; (2) there are multiple types of calcium channels in Lymnaea neurons; and (3) the effects of in vitro lead exposure differ qualitatively among channel types.

  14. Speed Control Of Separately Excited Dc Motor Using A High Efficiency Flyback Converter With New Active Clamp Technique M.Subramanyam*, K.Eswaramma

    Directory of Open Access Journals (Sweden)

    M.Subramanyam

    2014-10-01

    Full Text Available This paper deals with Speed control of separately excited DC motor using flyback converter with a new non complementary active clamp control method to achieve soft switching and high efficiency for heavy motor load and light load conditions. This is quite attractive for low power application with universal ac inputs, such as external adaptors. With the proposed control technique, the energy in the leakage inductance can be fully recycled. The soft switching can be achieved for the main switch and the absorbed leakage energy is transferred to the output and input side. In the Proposed model the resistive and DC motor is connected to flyback converter and it is simulated with different nominal voltages and rated speed is controlled at different levels for the N-type active clamp flyback converter and P-type active clamp flyback converter respectively. N-type active clamp flyback converter is suitable for high speed variation applications and P-type active clamp flyback converter is suitable for low speed variation applications.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    A new pulse width modulation (PWM) strategy which is an alternative approach of discontinuous PWM (DPWM) for a three-level neutral point clamped (NPC) inverter is developed and presented in this paper. The proposed PWM scheme not only takes advantage of the special properties available in NPC...... can be simplified. The salient features of the proposed scheme, as compared with the existing carrier-based DPWM strategies, are: 1) its reduced computational processing time, 2) its capability to balance the DC-link voltage without any additional control and 3) its reduced complexity e.g. only one...

  16. Study of the Contributions of Donor and Acceptor Photoexcitations to Open Circuit Voltage in Bulk Heterojunction Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Douglas Yeboah

    2017-10-01

    Full Text Available One of the key parameters in determining the power conversion efficiency (PCE of bulk heterojunction (BHJ organic solar cells (OSCs is the open circuit voltage . The processes of exciting the donor and acceptor materials individually in a BHJ OSC are investigated and are found to produce two different expressions for . Using the contributions of electron and hole quasi-Fermi levels and charge carrier concentrations, the two different expressions are derived as functions of the energetics of the donor and acceptor materials and the photo-generated charge carrier concentrations, and calculated for a set of donor-acceptor blends. The simultaneous excitation of both the donor and acceptor materials is also considered and the corresponding , which is different from the above two, is derived. The calculated from the photoexcitation of the donor is found to be somewhat comparable with that obtained from the photoexcitation of the acceptor in most combinations of the donor and acceptor materials considered here. It is also found that the calculated from the simultaneous excitations of donor and acceptor in BHJ OSCs is also comparable with the other two . All three thus derived produce similar results and agree reasonably well with the measured values. All three depend linearly on the concentration of the photoexcited charge carriers and hence incident light intensity, which agrees with experimental results. The outcomes of this study are expected to help in finding materials that may produce higher and hence enhanced PCE in BHJ OSCs.

  17. Umbilical cord serum lipids between early and late clamping in full-term newborns. A systematic assignment treatment group.

    Science.gov (United States)

    Florido, Jesús; de Paco-Matallana, Catalina; Quezada, M Soledad; Garrido-Sánchez, M Carmen; Padilla, Carmen; Ocón, Olga; Luna, Juan De Dios; Ochoa-Herrera, Julio Jose

    2015-01-01

    The aim of the current study was to determine any relationship between the timing of clamping of the umbilical cord and the lipid levels circulating in umbilical artery and vein. We studied a clinical trial with systematic assignment in 229 single-fetus full-term deliveries with normal gestational course and spontaneous delivery; out of these, 111 were subjected to early clamping (EC, within 10 s of delivery) and 118 to late clamping (LC, at 2 min). In all cases, total cholesterol (TC), triglycerides (TG), and phospholipids were measured in sera from umbilical artery and vein. TC and TG values were significantly higher in the EC group than in the LC group in both umbilical artery and vein. Comparing values between umbilical artery and vein in the two clamping groups, in the EC group, all studied lipids TC, TG and phospholipids were significantly higher in vein than in artery. In the LC group, only TC was higher in vein. Umbilical cord lipid levels are related to the timing of umbilical cord clamping, finding which is noteworthy, because they are essential component of postnatal development. Our study confirms that delivery acts as an important modifier of fetal lipid levels.

  18. Experimental and Theoretical Study of 4H-SiC JFET Threshold Voltage Body Bias Effect from 25 C to 500 C

    Science.gov (United States)

    Neudeck, Philip G.; Spry, David J.; Chen, Liangyu

    2015-01-01

    This work reports a theoretical and experimental study of 4H-SiC JFET threshold voltage as a function of substrate body bias, device position on the wafer, and temperature from 25 C (298K) to 500 C (773K). Based on these results, an alternative approach to SPICE circuit simulation of body effect for SiC JFETs is proposed.

  19. Study of imbalanced internal resistance on drop voltage of LiFePO4 battery system connected in parallel

    Science.gov (United States)

    Adie Perdana, Fengky; Supriyanto, Agus; Purwanto, Agus; Jamaluddin, Anif

    2017-01-01

    The purpose of this research focuses on the effect of imbalanced internal resistance for the drop voltage of LiFePO4 18650 battery system connected in parallel. The battery pack has been assembled consist of two cell battery LiFePO4 18650 that has difference combination of internal resistance. Battery pack was tested with 1/C constant current charging, 3,65V per group sel, 3,65V constant voltage charging, 5 minutes of rest time between charge and discharge process, 1/2C Constant current discharge until 2,2V, 26 cycle of measurement test, and 4320 minutes rest time after the last charge cycle. We can conclude that the difference combination of internal resistance on the battery pack seriously influence the drop voltage of a battery. Theoretical and experimental result show that the imbalance of internal resistance during cycling are mainly responsible for the drop voltage of LiFePO4 parallel batteries. It is thus a good way to avoid drop voltage fade of parallel battery system by suppressing variations of internal resistance.

  20. Using physiology to guide time to cord clamping.

    Science.gov (United States)

    Kluckow, Martin; Hooper, Stuart B

    2015-08-01

    Immediate clamping and cutting of the umbilical cord at birth has been the accepted standard of care for decades. The physiologic rationale relating umbilical cord clamping (UCC) to the events of the circulatory transition is not considered in arbitrarily recommended cord clamping times. Systematic review of early versus deferred UCC shows significant hemodynamic benefits to the deferred group. Mechanisms for this protective effect are considered in this review. The original concept of a placental transfusion with a volume load and prevention of low cardiac output relies on the physiological end point of the amount of blood transfused. The newer concept of an ordered physiological transition is increasingly supported. This model places aeration of the lungs and an increase in pulmonary blood flow back at the centre of the circulatory transition with timing of UCC being related to establishment of respiration. The need for "physiologically based" UCC is discussed. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  1. A Voltage Quality Detection Method

    DEFF Research Database (Denmark)

    Chen, Zhe; Wei, Mu

    2008-01-01

    This paper presents a voltage quality detection method based on a phase-locked loop (PLL) technique. The technique can detect the voltage magnitude and phase angle of each individual phase under both normal and fault power system conditions. The proposed method has the potential to evaluate vario...... power quality disturbances, such as interruptions, sags and imbalances. Simulation studies have been performed. The effectiveness of the proposed method has been demonstrated under the simulated typical power disturbances....

  2. 一种改进的适用于膜片钳记录的成年大鼠海马神经元急性分离法%An improved method for acute isolation of neurons from the hippocampus of adult rats suitable for patch-clamping study

    Institute of Scientific and Technical Information of China (English)

    李晓明; 李建国; 杨建明; 胡平; 李晓文; 王颖; 覃鲁宁; 高天明

    2004-01-01

    An improved method is described for fast and reliable isolation of neurons from hippocampus of adult rats by acombination of mechanical and enzymatic means. The procedure allows the isolation of neurons from 500~600-d-old rats (over300 g), preserving the proximal dendritic structure without impairing the electrical characteristics of the cells. Morphologicallydistinct neurons can be recognized. Using cell-attached, inside-out and whole-cell configurations of patch clamp technique, it wasshown that the enzymatically isolated neurons in hippocampus from rats weighing more than 300 g exhibited voltage-gatedcalcium, sodium and potassium currents, outwardly rectifying chloride channel and large conductance Ca2+-activated potassiumchannel currents. Approximately, 95% of healthy cells allowed the formation of giga-ohm seals.%本文建立了一种快速、可靠的急性分离成年大鼠海马神经细胞的方法.此法可将实验大鼠的年龄提高到500 d以上,体重300 g以上;不损伤神经细胞膜的电学特性;形态上有差异的细胞易于分辨.用膜片钳技术的单通道和全细胞模式证实,在本实验条件下,约95%左右的健康细胞均能形成高阻抗封接,并成功地记录了电压依赖性钾、钠、钙通道,外向整流氯通道和大电导的钙激活钾通道电流.

  3. A systematic review and meta-analysis of a brief delay in clamping the umbilical cord of preterm infants.

    Science.gov (United States)

    Rabe, Heike; Reynolds, Graham; Diaz-Rossello, Jose

    2008-01-01

    The optimal timing of clamping the umbilical cord in preterm infants at birth is the subject of continuing debate. To investigate the effects of a brief delay in cord clamping on the outcome of babies born prematurely. A retrospective meta-analysis of randomised trials in preterm infants was conducted. Data were collected from published studies identified by a structured literature search in EMBASE, PubMed, CINAHL and the Cochrane Library. All infants born below 37 weeks gestation and enrolled into a randomised study of delayed cord clamping (30 s or more) versus immediate cord clamping (less than 20 s) after birth were included. Systematic search and analysis of the data were done according to the methodology of the Cochrane collaboration. Ten studies describing a total of 454 preterm infants were identified which met the inclusion and assessment criteria. Major benefits of the intervention were higher circulating blood volume during the first 24 h of life, less need for blood transfusions (p = 0.004) and less incidence of intraventricular hemorrhage (p = 0.002). The procedure of a delayed cord clamping time of at least 30 s is safe to use and does not compromise the preterm infant in the initial post-partum adaptation phase. (c) 2007 S. Karger AG, Basel

  4. Scorpion toxin prolongs an inactivation phase of the voltage-dependent sodium current in rat isolated single hippocampal neurons.

    Science.gov (United States)

    Kaneda, M; Oyama, Y; Ikemoto, Y; Akaike, N

    1989-05-15

    The effects of scorpion toxin on the voltage-dependent sodium current (INa) of CA1 pyramidal neurons isolated from rat hippocampus were studied under the single-electrode voltage-clamp condition using a 'concentration-clamp' technique. The toxin increased the peak amplitude of INa and prolonged its inactivation phase in a time- and dose-dependent manner. Inactivation phase of INa proceeded with two exponential components in the absence (control) and presence of the toxin. In the toxin-treated neurons, both the time constant of slow component and its fractional contribution to the total current increased dose-dependently while the fractional contribution of the fast one decreased in a dose-dependent fashion without changing its time constant. Actions of scorpion toxin on the sodium channels of hippocampal pyramidal neurons were essentially similar to those of peripheral preparations. Therefore, it can be concluded that the sodium channels of mammalian brain neurons have structures and functions similar to peripheral channels.

  5. Perforated patch-clamp analysis of the passive membrane properties of three classes of hippocampal neurons.

    Science.gov (United States)

    Spruston, N; Johnston, D

    1992-03-01

    1. Perforated patch-clamp recordings were made from the three major classes of hippocampal neurons in conventional in vitro slices prepared from adult guinea pigs. This technique provided experimental estimates of passive membrane properties (input resistance, RN, and membrane time constant, tau m) determined in the absence of the leak conductance associated with microelectrode impalement or the washout of cytoplasmic constituents associated with conventional whole-cell recordings. 2. To facilitate comparison of our data with previous results and to determine the passive membrane properties under conditions as physiological as possible, recordings were made at the resting potential, in physiological saline, and without any added blockers of voltage-dependent conductances. 3. Membrane-potential responses to current steps were analyzed, and four criteria were used to identify voltage responses that were the least affected by activation of voltage-dependent conductances. tau m was estimated from the slowest component (tau 0) of multiexponential fits of responses deemed passive by these criteria. RN was estimated from the slope of the linear region in the hyperpolarizing direction of the voltage-current relation. 4. It was not possible to measure purely passive membrane properties that were completely independent of membrane potential in any of the three classes of hippocampal neurons. Changing the membrane potential by constant current injection resulted in changes in RN and tau 0; subthreshold depolarization produced an increase, and hyperpolarization a decrease, in both RN and tau 0 for all three classes of hippocampal neurons. 5. Each of the three classes of hippocampal neurons also displayed a depolarizing "sag" during larger hyperpolarizing voltage transients. To evaluate the effect of the conductances underlying this sag on passive membrane properties, 2-5 mM Cs+ was added to the physiological saline. Extracellular Cs+ effectively blocked the sag in all three

  6. Study on Factors for Accurate Open Circuit Voltage Characterizations in Mn-Type Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Natthawuth Somakettarin

    2017-03-01

    Full Text Available Open circuit voltage (OCV of lithium batteries has been of interest since the battery management system (BMS requires an accurate knowledge of the voltage characteristics of any Li-ion batteries. This article presents an OCV characteristic for lithium manganese oxide (LMO batteries under several experimental operating conditions, and discusses factors for accurate OCV determination. A test system is developed for OCV characterization based on the OCV pulse test method. Various factors for the OCV behavior, such as resting period, step-size of the pulse test, testing current amplitude, hysteresis phenomena, and terminal voltage relationship, are investigated and evaluated. To this end, a general OCV model based on state of charge (SOC tracking is developed and validated with satisfactory results.

  7. Plasma temperature clamping in filamentation laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; Yeak, J.; Phillips, Mark C.

    2015-10-19

    Ultrafast laser filament induced breakdown spectroscopy is a very promising method for remote material detection. We present characteristics of plasmas generated in a metal target by laser filaments in air. Our measurements show that the temperature of the ablation plasma is clamped along the filamentation channel due to intensity clamping in a filament. Nevertheless, significant changes in radiation intensity are noticeable, and this is essentially due to variation in the number density of emitting atoms. The present results also partly explains the reason for the occurrence of atomic plume during fs LIBS in air compared to long-pulse ns LIBS.

  8. The problem of isotropic rectangular plate with four clamped edges

    Indian Academy of Sciences (India)

    C Erdem İmrak; Ismail Gerdemeli

    2007-06-01

    The examination of the exact solution of the governing equation of the rectangular plate is important for many reasons. This report discusses in exact solution of the governing equation of an isotropic rectangular plate with four clamped edges. A numerical method for clamped isotropic rectangular plate under distributed loads and an exact solution of the governing equation in terms of trigonometric and hyperbolic function are given. Finally, an illustrative example is given and the results are compared with those reported earlier. This method is found to be easier and effective. The results show reasonable agreement with other available results, but with a simpler and practical approach.

  9. Influence of tube voltage on digitized image qualityof patients exposed to occupational dust: phantoms and clinical studies

    Institute of Scientific and Technical Information of China (English)

    Wang Xiaohua; Liu Dongsheng; Xuan Xiao; Duan Jianghui; Yuan Huishu

    2014-01-01

    Background High-voltage analog X-ray examination is a main tool for pneumoconiosis,which is challenged by digital radiography (DR).The tube voltage of DR chest films required for diagnosis and staging of pneumoconiosis is concerned technically.We investigated the influence of the tube voltage on chest X-ray DR image quality of patients exposed to occupational dust.Methods DR images of the CDRAD2.0model,an anatomical chest phantom,and 136 exposed workers were analyzed at different tube voltages by threereaders.Image quality factors (IQF) were calculated and compared using the CDRAD2.0 model.DR images of ten anatomic positions were scored against those of the high-kilovolt chest films in anatomical phantom and clinical cases,and differences in scores were analyzed.Results In the CDRAD2.0 model,all three readers had a minimal IQF at 120 kV (mean:22.25 kV).The differences in the mean IQF of DR images at different tube voltages was significant (F=13.78,P<0.001).The IQF of DR imaging at 120 kV was similar to high kilovolt analog imaging (t=-0.58,P>0.05).In the anatomic phantom and clinical cases,the DR images at 120 kV were closest in anatomical detail to the high W analog images,and the means were similar (P>0.05).Conclusions Among different tube voltages,DR image quality is closest to the high kilovolt analog images at 120 kV in patients exposed to occupational dust.

  10. Automatic voltage imbalance detector

    Science.gov (United States)

    Bobbett, Ronald E.; McCormick, J. Byron; Kerwin, William J.

    1984-01-01

    A device for indicating and preventing damage to voltage cells such as galvanic cells and fuel cells connected in series by detecting sequential voltages and comparing these voltages to adjacent voltage cells. The device is implemented by using operational amplifiers and switching circuitry is provided by transistors. The device can be utilized in battery powered electric vehicles to prevent galvanic cell damage and also in series connected fuel cells to prevent fuel cell damage.

  11. Proper Voltage-Dependent Ion Channel Function in Dysferlin-Deficient Cardiomyocytes.

    Science.gov (United States)

    Rubi, Lena; Gawali, Vaibhavkumar S; Kubista, Helmut; Todt, Hannes; Hilber, Karlheinz; Koenig, Xaver

    2015-01-01

    Dysferlin plays a decisive role in calcium-dependent membrane repair in myocytes. Mutations in the encoding DYSF gene cause a number of myopathies, e.g. limb-girdle muscular dystrophy type 2B (LGMD2B). Besides skeletal muscle degenerative processes, dysferlin deficiency is also associated with cardiac complications. Thus, both LGMD2B patients and dysferlin-deficient mice develop a dilated cardiomyopathy. We and others have recently reported that dystrophin-deficient ventricular cardiomyocytes from mouse models of Duchenne muscular dystrophy show significant abnormalities in voltage-dependent ion channels, which may contribute to the pathophysiology in dystrophic cardiomyopathy. The aim of the present study was to investigate if dysferlin, like dystrophin, is a regulator of cardiac ion channels. By using the whole cell patch-clamp technique, we compared the properties of voltage-dependent calcium and sodium channels, as well as action potentials in ventricular cardiomyocytes isolated from the hearts of normal and dysferlin-deficient (dysf) mice. In contrast to dystrophin deficiency, the lack of dysferlin did not impair the ion channel properties and left action potential parameters unaltered. In connection with normal ECGs in dysf mice these results suggest that dysferlin deficiency does not perturb cardiac electrophysiology. Our study demonstrates that dysferlin does not regulate cardiac voltage-dependent ion channels, and implies that abnormalities in cardiac ion channels are not a universal characteristic of all muscular dystrophy types. © 2015 S. Karger AG, Basel.

  12. Proper Voltage-Dependent Ion Channel Function in Dysferlin-Deficient Cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Lena Rubi

    2015-06-01

    Full Text Available Background/Aims: Dysferlin plays a decisive role in calcium-dependent membrane repair in myocytes. Mutations in the encoding DYSF gene cause a number of myopathies, e.g. limb-girdle muscular dystrophy type 2B (LGMD2B. Besides skeletal muscle degenerative processes, dysferlin deficiency is also associated with cardiac complications. Thus, both LGMD2B patients and dysferlin-deficient mice develop a dilated cardiomyopathy. We and others have recently reported that dystrophin-deficient ventricular cardiomyocytes from mouse models of Duchenne muscular dystrophy show significant abnormalities in voltage-dependent ion channels, which may contribute to the pathophysiology in dystrophic cardiomyopathy. The aim of the present study was to investigate if dysferlin, like dystrophin, is a regulator of cardiac ion channels. Methods and Results: By using the whole cell patch-clamp technique, we compared the properties of voltage-dependent calcium and sodium channels, as well as action potentials in ventricular cardiomyocytes isolated from the hearts of normal and dysferlin-deficient (dysf mice. In contrast to dystrophin deficiency, the lack of dysferlin did not impair the ion channel properties and left action potential parameters unaltered. In connection with normal ECGs in dysf mice these results suggest that dysferlin deficiency does not perturb cardiac electrophysiology. Conclusion: Our study demonstrates that dysferlin does not regulate cardiac voltage-dependent ion channels, and implies that abnormalities in cardiac ion channels are not a universal characteristic of all muscular dystrophy types.

  13. Actions of a hydrogen sulfide donor (NaHS) on transient sodium, persistent sodium, and voltage-gated calcium currents in neurons of the subfornical organ.

    Science.gov (United States)

    Kuksis, Markus; Ferguson, Alastair V

    2015-09-01

    Hydrogen sulfide (H2S) is an endogenously found gasotransmitter that has been implicated in a variety of beneficial physiological functions. This study was performed to investigate the cellular mechanisms underlying actions of H2S previously observed in subfornical organ (SFO), where H2S acts to regulate blood pressure through a depolarization of the membrane and an overall increase in the excitability of SFO neurons. We used whole cell patch-clamp electrophysiology in the voltage-clamp configuration to analyze the effect of 1 mM NaHS, an H2S donor, on voltage-gated potassium, sodium, and calcium currents. We observed no effect of NaHS on potassium currents; however, both voltage-gated sodium currents (persistent and transient) and the N-type calcium current had a depolarized activation curve and an enhanced peak-induced current in response to a series of voltage-step and ramp protocols run in the control and NaHS conditions. These effects were not responsible for the previously observed depolarization of the membrane potential, as depolarizing effects of H2S were still observed following block of these conductances with tetrodotoxin (5 μM) and ω-conotoxin-GVIA (100 nM). Our studies are the first to investigate the effect of H2S on a variety of voltage-gated conductances in a single brain area, and although they do not explain mechanisms underlying the depolarizing actions of H2S on SFO neurons, they provide evidence of potential mechanisms through which this gasotransmitter influences the excitability of neurons in this important brain area as a consequence of the modulation of multiple ion channels.

  14. Mixed voltage VLSI design

    Science.gov (United States)

    Panwar, Ramesh; Rennels, David; Alkalaj, Leon

    1993-01-01

    A technique for minimizing the power dissipated in a Very Large Scale Integration (VLSI) chip by lowering the operating voltage without any significant penalty in the chip throughput even though low voltage operation results in slower circuits. Since the overall throughput of a VLSI chip depends on the speed of the critical path(s) in the chip, it may be possible to sustain the throughput rates attained at higher voltages by operating the circuits in the critical path(s) with a high voltage while operating the other circuits with a lower voltage to minimize the power dissipation. The interface between the gates which operate at different voltages is crucial for low power dissipation since the interface may possibly have high static current dissipation thus negating the gains of the low voltage operation. The design of a voltage level translator which does the interface between the low voltage and high voltage circuits without any significant static dissipation is presented. Then, the results of the mixed voltage design using a greedy algorithm on three chips for various operating voltages are presented.

  15. 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.

  16. Using rf voltage induced ferromagnetic resonance to study the spin-wave density of states and the Gilbert damping in perpendicularly magnetized disks

    Science.gov (United States)

    Devolder, Thibaut

    2017-09-01

    We study how the shape of the spin-wave resonance lines in rf voltage induced FMR can be used to extract the spin-wave density of states and the Gilbert damping within the precessing layer in nanoscale magnetic tunnel junctions that possess perpendicular magnetic anisotropy. We work with a field applied along the easy axis to preserve the cylindrical symmetry of the uniaxial perpendicularly magnetized systems. We first describe the experimental setup to study the susceptibility contributions of the spin waves in the field-frequency space. We then identify experimentally the maximum device size above which the spin waves confined in the free layer can no longer be studied in isolation as the linewidths of their discrete responses make them overlap into a continuous density of states. The rf voltage induced signal is the sum of two voltages that have comparable magnitudes: a first voltage that originates from the linear transverse susceptibility and rectification by magnetoresistance and a second voltage that arises from the nonlinear longitudinal susceptibility and the resultant time-averaged change of the exact micromagnetic configuration of the precessing layer. The transverse and longitudinal susceptibility signals have different dc bias dependencies such that they can be separated by measuring how the device rectifies the rf voltage at different dc bias voltages. The transverse and longitudinal susceptibility signals have different line shapes; their joint studies in both fixed field-variable frequency, or fixed frequency-variable field configurations can yield the Gilbert damping of the free layer of the device with a degree of confidence that compares well with standard ferromagnetic resonance. Our method is illustrated on FeCoB-based free layers in which the individual spin waves can be sufficiently resolved only for disk diameters below 200 nm. The resonance line shapes on devices with 90-nm diameters are consistent with a Gilbert damping of 0.011 . A single

  17. A dnaN plasmid shuffle strain for rapid in vivo analysis of mutant Escherichia coli β clamps provides insight into the role of clamp in umuDC-mediated cold sensitivity.

    Directory of Open Access Journals (Sweden)

    Vignesh M P Babu

    Full Text Available The E. coli umuDC gene products participate in two temporally distinct roles: UmuD2C acts in a DNA damage checkpoint control, while UmuD'2C, also known as DNA polymerase V (Pol V, catalyzes replication past DNA lesions via a process termed translesion DNA synthesis. These different roles of the umuDC gene products are managed in part by the dnaN-encoded β sliding clamp protein. Co-overexpression of the β clamp and Pol V severely blocked E. coli growth at 30°C. We previously used a genetic assay that was independent of the ability of β clamp to support E. coli viability to isolate 8 mutant clamp proteins (βQ61K, βS107L, βD150N, βG157S, βV170M, βE202K, βM204K and βP363S that failed to block growth at 30°C when co-overexpressed with Pol V. It was unknown whether these mutant clamps were capable of supporting E. coli viability and normal umuDC functions in vivo. The goals of this study were to answer these questions. To this end, we developed a novel dnaN plasmid shuffle assay. Using this assay, βD150N and βP363S were unable to support E. coli viability. The remaining 6 mutant clamps, each of which supported viability, were indistinguishable from β+ with respect to umuDC functions in vivo. In light of these findings, we analyzed phenotypes of strains overexpressing either β clamp or Pol V alone. The strain overexpressing β+, but not those expressing mutant β clamps, displayed slowed growth irrespective of the incubation temperature. Moreover, growth of the Pol V-expressing strain was modestly slowed at 30°, but not 42°C. Taken together, these results suggest the mutant clamps were identified due to their inability to slow growth rather than an inability to interact with Pol V. They further suggest that cold sensitivity is due, at least in part, to the combination of their individual effects on growth at 30°C.

  18. A dnaN plasmid shuffle strain for rapid in vivo analysis of mutant Escherichia coli β clamps provides insight into the role of clamp in umuDC-mediated cold sensitivity.

    Science.gov (United States)

    Babu, Vignesh M P; Sutton, Mark D

    2014-01-01

    The E. coli umuDC gene products participate in two temporally distinct roles: UmuD2C acts in a DNA damage checkpoint control, while UmuD'2C, also known as DNA polymerase V (Pol V), catalyzes replication past DNA lesions via a process termed translesion DNA synthesis. These different roles of the umuDC gene products are managed in part by the dnaN-encoded β sliding clamp protein. Co-overexpression of the β clamp and Pol V severely blocked E. coli growth at 30°C. We previously used a genetic assay that was independent of the ability of β clamp to support E. coli viability to isolate 8 mutant clamp proteins (βQ61K, βS107L, βD150N, βG157S, βV170M, βE202K, βM204K and βP363S) that failed to block growth at 30°C when co-overexpressed with Pol V. It was unknown whether these mutant clamps were capable of supporting E. coli viability and normal umuDC functions in vivo. The goals of this study were to answer these questions. To this end, we developed a novel dnaN plasmid shuffle assay. Using this assay, βD150N and βP363S were unable to support E. coli viability. The remaining 6 mutant clamps, each of which supported viability, were indistinguishable from β+ with respect to umuDC functions in vivo. In light of these findings, we analyzed phenotypes of strains overexpressing either β clamp or Pol V alone. The strain overexpressing β+, but not those expressing mutant β clamps, displayed slowed growth irrespective of the incubation temperature. Moreover, growth of the Pol V-expressing strain was modestly slowed at 30°, but not 42°C. Taken together, these results suggest the mutant clamps were identified due to their inability to slow growth rather than an inability to interact with Pol V. They further suggest that cold sensitivity is due, at least in part, to the combination of their individual effects on growth at 30°C.

  19. CO₂ and O₂ evolution at high voltage cathode materials of Li-ion batteries: a differential electrochemical mass spectrometry study.

    Science.gov (United States)

    Wang, Hongsen; Rus, Eric; Sakuraba, Takahito; Kikuchi, Jun; Kiya, Yasuyuki; Abruña, Héctor D

    2014-07-01

    A three-electrode differential electrochemical mass spectrometry (DEMS) cell has been developed to study the oxidative decomposition of electrolytes at high voltage cathode materials of Li-ion batteries. In this DEMS cell, the working electrode used was the same as the cathode electrode in real Li-ion batteries, i.e., a lithium metal oxide deposited on a porous aluminum foil current collector. A charged LiCoO2 or LiMn2O4 was used as the reference electrode, because of their insensitivity to air, when compared to lithium. A lithium sheet was used as the counter electrode. This DEMS cell closely approaches real Li-ion battery conditions, and thus the results obtained can be readily correlated with reactions occurring in real Li-ion batteries. Using DEMS, the oxidative stability of three electrolytes (1 M LiPF6 in EC/DEC, EC/DMC, and PC) at three cathode materials including LiCoO2, LiMn2O4, and LiNi(0.5)Mn(1.5)O4 were studied. We found that 1 M LiPF6 + EC/DMC electrolyte is quite stable up to 5.0 V, when LiNi(0.5)Mn(1.5)O4 is used as the cathode material. The EC/DMC solvent mixture was found to be the most stable for the three cathode materials, while EC/DEC was the least stable. The oxidative decomposition of the EC/DEC mixture solvent could be readily observed under operating conditions in our cell even at potentials as low as 4.4 V in 1 M LiPF6 + EC/DEC electrolyte on a LiCoO2 cathode, as indicated by CO2 and O2 evolution. The features of this DEMS cell to unveil solvent and electrolyte decomposition pathways are also described.

  20. Short Hypoxia Does not Affect Plasma Leptin in Healthy Men under Euglycemic Clamp Conditions

    Directory of Open Access Journals (Sweden)

    Andre Schmoller

    2009-01-01

    Full Text Available Leptin is involved in the endocrine control of energy expenditure and body weight regulation. Previous studies emphasize a relationship between hypoxic states and leptin concentrations. The aim of this study was to investigate the effects of acute hypoxia on leptin concentrations in healthy subjects. We examined 14 healthy men. Hypoxic conditions were induced by decreasing oxygen saturation to 75% for 30 minutes. Plasma leptin concentrations were determined at baseline, after 3 hours of euglycemic clamping, during hypoxia, and repeatedly the following 2.5 hours thereafter. Our results show an increase of plasma leptin concentrations in the course of 6 hours of hyperinsulinemic-euglycemic clamping which may reflect diurnal rhythmicity. Notwithstanding, there was no difference between levels of leptin in the hypoxic and the normoxic condition (=.2. Since we did not find any significant changes in leptin responses upon hypoxia, plasma leptin levels do not seem to be affected by short hypoxic episodes of moderate degree.