WorldWideScience

Sample records for voltage clamp techniques

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.  

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. High voltage test techniques

    CERN Document Server

    Kind, Dieter

    2001-01-01

    The second edition of High Voltage Test Techniques has been completely revised. The present revision takes into account the latest international developments in High Voltage and Measurement technology, making it an essential reference for engineers in the testing field.High Voltage Technology belongs to the traditional area of Electrical Engineering. However, this is not to say that the area has stood still. New insulating materials, computing methods and voltage levels repeatedly pose new problems or open up methods of solution; electromagnetic compatibility (EMC) or components and systems al

  13. 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...

  14. 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...

  15. 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

  16. 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

  17. 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)

  18. 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....

  19. 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.

  20. 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)

  1. 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.

  2. 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...

  3. 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

  4. 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....

  5. 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.

  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. 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).

  8. 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)

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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....

  20. 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...

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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....

  8. Offset Correction Techniques for Voltage Sense Amplifiers

    NARCIS (Netherlands)

    Groeneveld, S.

    2006-01-01

    This report deals with offset correction techniques for voltage sense amplifiers and is divided into two different parts: 1) mismatch and 2) offset correction techniques. First a literature study is done on the subject mismatch with specially focus on the future. Mismatch of a transistor is determin

  9. 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...

  10. 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

  11. 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.

  12. High-voltage test and measuring techniques

    CERN Document Server

    Hauschild, Wolfgang

    2014-01-01

    It is the intent of this book to combine high-voltage (HV) engineering with HV testing technique and HV measuring technique. Based on long-term experience gained by the authors as lecturer and researcher as well as member in international organizations, such as IEC and CIGRE, the book will reflect the state of the art as well as the future trends in testing and diagnostics of HV equipment to ensure a reliable generation, transmission and distribution of electrical energy. The book is intended not only for experts but also for students in electrical engineering and high-voltage engineering.

  13. 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.

  14. High-voltage test and measuring techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hauschild, Wolfgang; Lemke, Eberhard

    2014-04-01

    Reflects the unit of both HV testing and measuring technique. Intended as an ''application guide'' for the relevant IEC standards. Refers also to future trends in HV testing and measuring technique. With numerous illustrations. It is the intent of this book to combine high-voltage (HV) engineering with HV testing technique and HV measuring technique. Based on long-term experience gained by the authors as lecturer and researcher as well as member in international organizations, such as IEC and CIGRE, the book will reflect the state of the art as well as the future trends in testing and diagnostics of HV equipment to ensure a reliable generation, transmission and distribution of electrical energy. The book is intended not only for experts but also for students in electrical engineering and high-voltage engineering.

  15. 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...

  16. 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.

  17. Gain-clamping techniques in two-stage double-pass L-band EDFA

    Indian Academy of Sciences (India)

    S W harun; N Md Samsuri; H Ahmad

    2006-03-01

    Two designs of long-wavelength band erbium-doped fiber amplifier (L-band EDFA) for gain clamping in double-pass systems are demonstrated and compared. The first design is based on ring laser technique where a backward amplified spontaneous emission (ASE) from the second stage is routed into the feedback loop to create an oscillating laser for gain clamping. The gain is clamped at 18.6 dB from -40 to -8 dBm with a gain variation of less than ± 0.1 dB and a noise figure of less than 6 dB. Another scheme is based on partial reflection of ASE into the EDFA, which is demonstrated using a narrowband fiber Bragg grating. This scheme achieves a good gain clamping characteristic up to -12 dBm of input signal power with a gain variation of less than ± 0.3 dB from a clamped gain of 22 dB. The noise figure of a 1580 nm signal is maintained below 5 dB in this amplifier since this scheme is not based on lasing mechanism. The latter scheme is also expected to be free from the relaxation oscillation problem.

  18. 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.

  19. 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.

  20. Soft computing techniques in voltage security analysis

    CERN Document Server

    Chakraborty, Kabir

    2015-01-01

    This book focuses on soft computing techniques for enhancing voltage security in electrical power networks. Artificial neural networks (ANNs) have been chosen as a soft computing tool, since such networks are eminently suitable for the study of voltage security. The different architectures of the ANNs used in this book are selected on the basis of intelligent criteria rather than by a “brute force” method of trial and error. The fundamental aim of this book is to present a comprehensive treatise on power system security and the simulation of power system security. The core concepts are substantiated by suitable illustrations and computer methods. The book describes analytical aspects of operation and characteristics of power systems from the viewpoint of voltage security. The text is self-contained and thorough. It is intended for senior undergraduate students and postgraduate students in electrical engineering. Practicing engineers, Electrical Control Center (ECC) operators and researchers will also...

  1. 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....

  2. 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...

  3. 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.

  4. 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

  5. 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.

  6. New Control Technique Applied in Dynamic Voltage Restorer for Voltage Sag Mitigation

    Directory of Open Access Journals (Sweden)

    Rosli Omar

    2010-01-01

    Full Text Available The Dynamic Voltage Restorer (DVR was a power electronics device that was able to compensate voltage sags on critical loads dynamically. The DVR consists of VSC, injection transformers, passive filters and energy storage (lead acid battery. By injecting an appropriate voltage, the DVR restores a voltage waveform and ensures constant load voltage. There were so many types of the control techniques being used in DVR for mitigating voltage sags. The efficiency of the DVR depends on the efficiency of the control technique involved in switching the inverter. Problem statement: Simulation and experimental investigation toward new algorithms development based on SVPWM. Understanding the nature of DVR and performance comparisons between the various controller technologies available. The proposed controller using space vector modulation techniques obtain higher amplitude modulation indexes if compared with conventional SPWM techniques. Moreover, space vector modulation techniques can be easily implemented using digital processors. Space vector PWM can produce about 15% higher output voltage than standard Sinusoidal PWM. Approach: The purpose of this research was to study the implementation of SVPWM in DVR. The proposed control algorithm was investigated through computer simulation by using PSCAD/EMTDC software. Results: From simulation and experimental results showed the effectiveness and efficiency of the proposed controller based on SVPWM in mitigating voltage sags in low voltage distribution systems. It was concluded that its controller also works well both in balance and unbalance conditions of voltages. Conclusion/Recommendations: The simulation and experimental results of a DVR using PSCAD/EMTDC software based on SVPWM technique showed clearly the performance of the DVR in mitigating voltage sags. The DVR operates without any difficulties to inject the appropriate voltage component to correct rapidly any anomaly in the supply voltage to keep the

  7. Force-clamp analysis techniques reveal stretched exponential unfolding kinetics in ubiquitin

    CERN Document Server

    Lannon, Herbert; Brujic, Jasna

    2012-01-01

    Force-clamp spectroscopy reveals the unfolding and disulfide bond rupture times of single protein molecules as a function of the stretching force, point mutations and solvent conditions. The statistics of these times reveal whether the protein domains are independent of one another, the mechanical hierarchy in the polyprotein chain, and the functional form of the probability distribution from which they originate. It is therefore important to use robust statistical tests to decipher the correct theoretical model underlying the process. Here we develop multiple techniques to compare the well-established experimental data set on ubiquitin with existing theoretical models as a case study. We show that robustness against filtering, agreement with a maximum likelihood function that takes into account experimental artifacts, the Kuiper statistic test and alignment with synthetic data all identify the Weibull or stretched exponential distribution as the best fitting model. Our results are inconsistent with recently ...

  8. Zero-voltage switching technique in dc/dc converters

    Science.gov (United States)

    Liu, Kwang-Hwa; Lee, Fred C. Y.

    1990-07-01

    A novel resonant switch operating under the principle of zero-voltage switching is presented. In contrast to the zero-current switching, this technique eliminates the switching loss and dv/dt noise due to the discharging of MOSFET junction capacitances and the reverse recovery of diodes, and enables the converters to operate at high frequencies. A dc analysis of the converter is carried out. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. The two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buck converter and a voltage-mode quasi-resonant boost converter. A 5-MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. The circuit contains the smallest number of components possible, and yet maintains high efficiency at high switching frequency.

  9. Medium voltage switching techniques; Techniques de coupure en moyenne tension

    Energy Technology Data Exchange (ETDEWEB)

    Theoleyre, S. [Schneider Electric S.A., 92 - Boulogne-Billancourt (France)

    1999-08-01

    The link between power production plants and users is ensured by a grid or an arborescence of connections, lines and cables. For exploitation, maintenance or safety reasons it may be necessary to switch off and switch on the current at any point of the network. Switching devices are used for this purpose and the choice of a given device depends on the nature of the current (load, overload and fault currents) and of the domain of application. During switching and during continuous operation, these devices are submitted to dielectric, thermal, electrodynamical and mechanical stresses. The most important stresses are those linked with transient phenomena and involving an electric arc. This paper deals principally with the switching of medium voltage (1 to 52 kV) AC currents using circuit breakers. The first part analyzes the phenomena that occur during the operation of circuit breakers while the second part presents the four switching techniques currently used: in air, oil, vacuum and in sulfur hexafluoride (SF{sub 6}). (J.S.) 35 refs.

  10. 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.

  11. Measurement of the cell membrane capacitance and conductance of colonic crypt cells of the rat using the patch clamp technique

    CERN Document Server

    Schill, C

    2005-01-01

    Using the patch clamp technique the membrane capacitance and membrane conductance of colonic crypt cells of the rat was measured. The influence of the intracellular agonists Ca++, cAMP and of osmotic changes on the membrane capacitance and conductance was studied.

  12. 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.

  13. Design techniques for low-voltage analog integrated circuits

    Science.gov (United States)

    Rakús, Matej; Stopjaková, Viera; Arbet, Daniel

    2017-08-01

    In this paper, a review and analysis of different design techniques for (ultra) low-voltage integrated circuits (IC) are performed. This analysis shows that the most suitable design methods for low-voltage analog IC design in a standard CMOS process include techniques using bulk-driven MOS transistors, dynamic threshold MOS transistors and MOS transistors operating in weak or moderate inversion regions. The main advantage of such techniques is that there is no need for any modification of standard CMOS structure or process. Basic circuit building blocks like differential amplifiers or current mirrors designed using these approaches are able to operate with the power supply voltage of 600 mV (or even lower), which is the key feature towards integrated systems for modern portable applications.

  14. Inverter-based circuit design techniques for low supply voltages

    CERN Document Server

    Palani, Rakesh Kumar

    2017-01-01

    This book describes intuitive analog design approaches using digital inverters, providing filter architectures and circuit techniques enabling high performance analog circuit design. The authors provide process, supply voltage and temperature (PVT) variation-tolerant design techniques for inverter based circuits. They also discuss various analog design techniques for lower technology nodes and lower power supply, which can be used for designing high performance systems-on-chip.    .

  15. A technique to reduce plasma armature formation voltage

    Energy Technology Data Exchange (ETDEWEB)

    Jamison, K.A. (Science Applications International Corp., Shalimar, FL (US)); Littrell, D.M. (Air Force Armament Lab., Eglin AFB, FL (United States))

    1991-01-01

    The initiation of a plasma armature by foil vaporization in a railgun is often accompanied by a large, fast, voltage transient appearing on both the breech and muzzle of the gun. For a railgun driven by an inductor/opening switch power supply, this voltage transient becomes a concern during current commutation from the switch to the railgun. To lessen the requirements on the opening switch, techniques must be found to reduce the armature formation voltage. This paper presents the experimental results from railgun firings at AFATL's Electromagnetic Launcher Basic Research Facility (Site A-15, Eglin Air Force Base, Florida) using different shapes of initiation foils. These foils have been designed to vaporize into a plasma armature with reduced transient voltages. A design criteria was developed to ensure that all portions of the foil vaporize at slightly different times.

  16. 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...

  17. 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...

  18. 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.

  19. 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.

  20. 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.

  1. Analysis of Discontinuous Space Vector PWM Techniques for a Seven-Phase Voltage Source Inverter

    Directory of Open Access Journals (Sweden)

    Mohd. Arif Khan

    2012-03-01

    Full Text Available This paper presents discontinuous space vector PWM (DPWM techniques for a seven-phase voltage source inverter (VSI. Space vector model of a seven-phase VSI shows that there exist 128 space vectors with different lengths and maps into fourteen sided polygons. A number of possibilities could arise to implement modulation of inverter legs due to large number of available space voltage vectors. Two strategies are adopted here; one utilising large and two middle sets of space vectors to implement discontinuous space vector PWM. Clamping of legs of inverter to either positive or negative dc bus leads to discontinuity in the switching and consequently offers reduced switching loss modulation strategy. A significant reduction in switching losses can be achieved while employing DPWM in a seven-phase VSI. A generalised method is also proposed to realize the DPWM in a seven-phase VSI. Comparison of continuous and discontinuous PWM is presented in terms of switching current ripple. The experimental set-up is illustrated and the experimental results are presented.

  2. Dynamic Voltage Restorer Based on Space Vector Pulse Width Modulation Technique

    Directory of Open Access Journals (Sweden)

    B.N S P Venkatesh

    2011-07-01

    Full Text Available Power Quality problems encompass a wide range of disturbances such as voltage sags, swells, flicker,harmonics distortion and interruptions. The strategic deployment of custom power devices has been proposed asone of the means to protect sensitive loads from power quality problems such as voltage sags and swells. The Dynamic Voltage Restorer (DVR is a power electronic device that is used to inject 3-phase voltage in series and in synchronism with the distribution feeder voltages in order to compensate voltage sag and similarly itreacts quickly to inject the appropriate voltage component (negative voltage magnitude in order to compensate voltage swell. The principal component of the DVR is a voltage source inverter that generates three phase voltages and provides the voltage support to a sensitive load during voltage sags and swells. Pulse Width Modulation Technique is very critical for proper control of DVR. Sinusoidal Pulse Width Modulation (SPWM and Space Vector Pulse Width Modulation (SVPWM control techniques are used for controlling the DVR. Inthis work, the operation of DVR is presented and the control technique used for voltage source inverter is Space Vector PWM technique. Space vector PWM can utilize the better dc voltage and generates the fewer harmonic in inverter output voltage than Sinusoidal PWM technique. This work describes the DVR based on Space Vector PWM which provides voltage support to sensitive loads and is simulated by using MATLAB/SIMULINK. Simulation results show that the control approach is able to compensate for any type of voltage sags and swells.

  3. Pollution Maintenance Techniques in Coastal High Voltage Installations

    Directory of Open Access Journals (Sweden)

    E. Pyrgioti

    2011-02-01

    Full Text Available Pollution of outdoor high voltage insulators is a common problem for utilities, with a considerable impact to power system reliability. In an effort to prevent possible flashovers due to pollution, many methods have been applied, aiming to improve the insulation performance, either by suppressing the formation of surface conductivity or by increasing the possible insulation level. In the case of substations, the selection of the appropriate technique is complex due to certain issues correlated to the nature of the installation. In this paper, several techniques usually implemented by utilities, are investigated based on the experienced gained in the case of Crete, a Greek island in southern Europe, where due to the coastal development of the power system, the majority of high voltage installations are exposed to intense marine pollution. The technique of coating insulators with Room Temperature Vulcanized Silicone Rubber (RTV SIR has proved rather efficient and therefore is presented extendedly. Correlation of the material behaviour with environmental conditions is discussed and results from long term monitoring, including environmental parameters and leakage current measurements, in a 150 kV Substation are presented. It is shown that RTV SIR coatings have remarkably suppressed surface activity and that porcelain insulators exhibit different activity period when coated.

  4. Negative voltage bandgap reference with multilevel curvature compensation technique

    Science.gov (United States)

    Xi, Liu; Qian, Liu; Xiaoshi, Jin; Yongrui, Zhao; Lee, Jong-Ho

    2016-05-01

    A novel high-order curvature compensation negative voltage bandgap reference (NBGR) based on a novel multilevel compensation technique is introduced. Employing an exponential curvature compensation (ECC) term with many high order terms in itself, in a lower temperature range (TR) and a multilevel curvature compensation (MLCC) term in a higher TR, a flattened and better effect of curvature compensation over the TR of 165 °C (-40 to 125 °C) is realised. The MLCC circuit adds two convex curves by using two sub-threshold operated NMOS. The proposed NBGR implemented in the Central Semiconductor Manufacturing Corporation (CSMC) 0.5 μm BCD technology demonstrates an accurate voltage of -1.183 V with a temperature coefficient (TC) as low as 2.45 ppm/°C over the TR of 165 °C at a -5.0 V power supply; the line regulation is 3 mV/V from a -5 to -2 V supply voltage. The active area of the presented NBGR is 370 × 180 μm2. Project supported by the Fund of Liaoning Province Education Department (No. L2013045).

  5. 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。

  6. Process, Voltage and Temperature Compensation Technique for Cascode Modulated PAs

    DEFF Research Database (Denmark)

    Sira, Daniel; Larsen, Torben

    2013-01-01

    transconductance amplifier. The predistorted varying envelope signal is applied to the cascode gate of the PA. It is shown that the proposed PVT compensation technique significantly reduces the PVT spread of the PA linearity indicators and improves the PA linearity. Simulations were performed in a 0.13 μm CMOS......This paper presents a process, voltage and temperature (PVT) compensation method for a cascode modulated polar power amplifier (PA). It is shown that it is possible to create a baseband replica circuit of the PA that has the same AM-AM nonlinearity as the PA itself. The replica circuit......, that represents a transistor level model (empirical model) of the cascode modulated PA, is utilized in a PA analog predistorter. The analog predistorter linearizes and compensates for PVT variation of the cascode modulated PA. The empirical model is placed in the negative feedback of an operational...

  7. A robust and fast generic voltage sag detection technique

    DEFF Research Database (Denmark)

    L. Dantas, Joacillo; Lima, Francisco Kleber A.; Branco, Carlos Gustavo C.;

    2015-01-01

    In this paper, a fast and robust voltage sag detection algorithm, named VPS2D, is introduced. Using the DSOGI, the algorithm creates a virtual positive sequence voltage and monitories the fundamental voltage component of each phase. After calculating the aggregate value in the o:;3-reference frame......, the algorithm can rapidly identify the starting and the ending of symmetric and asymmetric voltage sags, even if there are harmonics on the grid. Simulation and experimental results are given to validate the proposed algorithm....

  8. Modified technique for aortic cross-clamping during liver donor procurement.

    Science.gov (United States)

    Desai, Chirag S; Girlanda, Raffaele; Hawksworth, Jason; Fishbein, Thomas M

    2014-05-01

    Undue tension on the donor vessels during organ procurement is associated with intimal dissection, which can form the nidus for the thrombosis of the hepatic artery (HA) and graft loss. According to the US OPTN database, 143 grafts were discarded in the last 15 yr due to vascular damage during procurement. The most common technique to expose the supraceliac aorta is dissection between the left lateral segment of the liver and the esophagus-stomach. In obese donors, due to restricted space and in pediatric donors where the vessels are very delicate and this space is very small, the replaced or accessory left HA(R/A LHA) is prone to damage if approached conventionally. We describe a technique for the exposure of the supraceliac aorta in which the aorta is approached from the left side behind the gastroesophageal junction that does not require division of the gastrohepatic ligament. From May 2007 to May 2013, 104 liver procurements were performed. Eighty-nine (85.6%) were adults, and 15 (14.4%) were pediatric donors. Twenty-three (22.1%) had R/A LHA. No donor organ suffered any damage. One adult recipient with R/A LHA suffered HA thrombosis not related to it. In summary, this technical modification offers improved safety during cadaveric procurement and increases the ease.

  9. Kidney clamp, perfuse, re-implant: a useful technique for graft salvage after vascular complications during kidney transplantation.

    Science.gov (United States)

    Mekeel, Kristin L; Halldorson, Jeffery B; Berumen, Jennifer A; Hemming, Alan W

    2015-04-01

    Although intra-operative vascular complications during renal transplantation are rare, injuries associated with prolonged ischemia may lead to graft threatening early and late complications. This series describes a novel technique for intra-operative repair of vascular complications in five patients over a three-yr period. The method consists of rapid graft nephrectomy and re-preservation of the graft with cold University of Wisconsin solution, which allows for controlled/precise back table repair of the vascular injury without incurring prolonged warm ischemia time. In three cases, the donor renal vein (2) and donor renal artery (1) were damaged and required back table reconstruction. In two cases, the recipient iliac artery needed reconstruction. Three of the five cases used deceased donor iliac vessels from another donor for reconstruction. Two patients required postoperative dialysis for delayed graft function for three to nine d (average six d) and two patients had slow graft function. All grafts were functioning at 17 months (mean) after transplant, with a median serum of 1.61 mg/dL (0.74-3.69). This series demonstrates the effectiveness of kidney clamp, perfuse, resuscitate as an effective intra-operative technique to salvage grafts after vascular injury. Although the grafts may suffer from delayed or slow graft function, excellent long-term function is attainable.

  10. Association of Sleep Deprivation With Reduction in Insulin Sensitivity as Assessed by the Hyperglycemic Clamp Technique in Adolescents.

    Science.gov (United States)

    De Bernardi Rodrigues, Ana Maria; da Silva, Cleliani de Cassia; Vasques, Ana Carolina Junqueira; Camilo, Daniella Fernandes; Barreiro, Francieli; Cassani, Roberta Soares Lara; Zambon, Mariana Porto; Antonio, Maria Ângela Reis de Góes Monteiro; Geloneze, Bruno

    2016-05-01

    The association between short sleep duration and decreased insulin sensitivity in adolescents has been described. However, to our knowledge, no studies have investigated this association measuring insulin sensitivity by the hyperglycemic clamp technique. To compare the distributions of parameters of insulin resistance in adolescents with sleep deprivation vs adequate sleep, and to investigate the association between sleep deprivation and insulin sensitivity. Cross-sectional multicenter study using data from the Brazilian Metabolic Syndrome Study conducted from June 29, 2011, to December 3, 2014, at an obesity outpatient clinic at the University of Campinas and public schools, with a convenience sample of 615 adolescents aged 10 to 19.9 years with a body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) for age and sex at the fifth percentile or higher. A subsample of 81 adolescents underwent the hyperglycemic clamp technique. The self-reported sleep duration was used to classify the population into 2 groups: adolescents with sleep deprivation (sleep (≥8 hours/night). Insulin sensitivity was assessed using the hyperglycemic clamp technique. Among the 615 adolescents (56.3% female; median age, 15.9 years [interquartile range, 12.9-17.8 years]) included in the sample, the mean (SD) sleep duration was 7.9 (1.7) hours/night. The adolescents with sleep deprivation (n = 257) compared with those with adequate sleep (n = 358) had a higher median (interquartile range) age (17.0 [15.4-18.3] vs 14.1 [11.8-16.9] years), BMI (25.0 [21.2-29.3] vs 23.1 [19.5-27.6]), waist circumference (83.0 [73.5-95.4] vs 79.0 [68.5-91.0] cm), sagittal abdominal diameter (17.9 [15.8-20.8] vs 17.0 [15.0-19.8] cm), neck circumference (35.2 [33.0-38.0] vs 33.0 [30.0-35.5] cm), uric acid level (4.9 [4.0-5.8] vs 4.5 [3.7-5.5] mg/dL), and white blood cell count (7000 [5900-8200] vs 6600 [5600-7800] cells/μL) (all P sleep deprivation had a lower median

  11. 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...

  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. A Survey on Voltage Boosting Techniques for Step-Up DC-DC Converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Gorji, Saman Asghari;

    2016-01-01

    , researches on new voltage boosting techniques are inevitable for various power converter applications. This can be achieved either by additional magnetic or by electric field storage elements with switching elements (switch and/or diode) in different configurations. Such combination of primary voltage...... boosting techniques and topologies are large, which at times may be confusing and difficult to follow/adapt for different applications. Considering these aspects and in order to make a clear sketch of the general law and framework of various voltage boosting techniques, this paper comprehensively reviews...... different voltage boosting techniques and categorizes them according to their circuit performance....

  14. SVPWM Technique with Varying DC-Link Voltage for Common Mode Voltage Reduction in a Matrix Converter and Analytical Estimation of its Output Voltage Distortion

    Science.gov (United States)

    Padhee, Varsha

    Common Mode Voltage (CMV) in any power converter has been the major contributor to premature motor failures, bearing deterioration, shaft voltage build up and electromagnetic interference. Intelligent control methods like Space Vector Pulse Width Modulation (SVPWM) techniques provide immense potential and flexibility to reduce CMV, thereby targeting all the afore mentioned problems. Other solutions like passive filters, shielded cables and EMI filters add to the volume and cost metrics of the entire system. Smart SVPWM techniques therefore, come with a very important advantage of being an economical solution. This thesis discusses a modified space vector technique applied to an Indirect Matrix Converter (IMC) which results in the reduction of common mode voltages and other advanced features. The conventional indirect space vector pulse-width modulation (SVPWM) method of controlling matrix converters involves the usage of two adjacent active vectors and one zero vector for both rectifying and inverting stages of the converter. By suitable selection of space vectors, the rectifying stage of the matrix converter can generate different levels of virtual DC-link voltage. This capability can be exploited for operation of the converter in different ranges of modulation indices for varying machine speeds. This results in lower common mode voltage and improves the harmonic spectrum of the output voltage, without increasing the number of switching transitions as compared to conventional modulation. To summarize it can be said that the responsibility of formulating output voltages with a particular magnitude and frequency has been transferred solely to the rectifying stage of the IMC. Estimation of degree of distortion in the three phase output voltage is another facet discussed in this thesis. An understanding of the SVPWM technique and the switching sequence of the space vectors in detail gives the potential to estimate the RMS value of the switched output voltage of any

  15. A Review on Power System Voltage Stability and Optimization Techniques

    Directory of Open Access Journals (Sweden)

    T. Madhuranthaka

    2016-11-01

    Full Text Available Power system voltage stability is a one of the major focused areas in recent days due to mismatch between generation and demand. Maintenance of voltage stability is a challenging issue in planning and security assessment of power systems. Voltage stability is the ability of a power system to maintain steady acceptable voltages at all buses in the power system under normal operating conditions and after being subjected to a disturbance. Long-term voltage instability problems can occur in heavily loaded systems where the electrical distance is large between the generator and the load. Timely application of reactive power compensation or load shedding may prevent this type of voltage instability. System reactive power handling capacity can be improved with Flexible AC Transmission System (FACTS devices. Identification of critical system locations to undertake appropriate remedial measures in operation is the concern. This paper reviews the performance of various types FACTS controllers in power system voltage stability problem and focuses on different optimization methods implemented for optimal placement and sizing of FACTS devices to minimize power losses.

  16. 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.

  17. F1FO ATPase vesicle preparation and technique for performing patch clamp recordings of submitochondrial vesicle membranes.

    Science.gov (United States)

    Sacchetti, Silvio; Alavian, Kambiz N; Lazrove, Emma; Jonas, Elizabeth A

    2013-05-04

    Mitochondria are involved in many important cellular functions including metabolism, survival(1), development and, calcium signaling(2). Two of the most important mitochondrial functions are related to the efficient production of ATP, the energy currency of the cell, by oxidative phosphorylation, and the mediation of signals for programmed cell death(3). The enzyme primarily responsible for the production of ATP is the F1FO-ATP synthase, also called ATP synthase(4-5). In recent years, the role of mitochondria in apoptotic and necrotic cell death has received considerable attention. In apoptotic cell death, BCL-2 family proteins such as Bax enter the mitochondrial outer membrane, oligomerize and permeabilize the outer membrane, releasing pro-apoptotic factors into the cytosol(6). In classic necrotic cell death, such as that produced by ischemia or excitotoxicity in neurons, a large, poorly regulated increase in matrix calcium contributes to the opening of an inner membrane pore, the mitochondrial permeability transition pore or mPTP. This depolarizes the inner membrane and causes osmotic shifts, contributing to outer membrane rupture, release of pro-apoptotic factors, and metabolic dysfunction. Many proteins including Bcl-xL(7) interact with F1FO ATP synthase, modulating its function. Bcl-xL interacts directly with the beta subunit of F1FO ATP synthase, and this interaction decreases a leak conductance within the F1FOATPasecomplex, increasing the net transport of H+ by F1FO during F1FO ATPase activity(8) and thereby increasing mitochondrial efficiency. To study the activity and modulation of the ATP synthase, we isolated from rodent brain submitochondrial vesicles (SMVs) containing F1FO ATPase. The SMVs retain the structural and functional integrity of the F1FO ATPase as shown in Alavian et al. Here, we describe a method that we have used successfully for the isolation of SMVs from rat brain and we delineate the patch clamp technique to analyze channel activity (ion

  18. Analog IC techniques for low-voltage low-power electronics

    NARCIS (Netherlands)

    Serdijn, W.A.; Verhoeven, C.J.M.; Van Roermund, A.H.M.

    1995-01-01

    Analog IC Techniques lor Low-Voltage Low Power Electronics addresses many very important, but recent, techniques which enable electronics to operate at a low supply voltage and consume a minimum amount of power. Apart from investigations at the device, circuit and system levels, the book provides a

  19. Analog IC techniques for low-voltage low-power electronics

    NARCIS (Netherlands)

    Serdijn, W.A.; Verhoeven, C.J.M.; Van Roermund, A.H.M.

    1995-01-01

    Analog IC Techniques lor Low-Voltage Low Power Electronics addresses many very important, but recent, techniques which enable electronics to operate at a low supply voltage and consume a minimum amount of power. Apart from investigations at the device, circuit and system levels, the book provides a

  20. Experimental evaluation of envelope tracking techniques for voltage disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Marei, Mostafa I. [Electrical Power and Machines Dept., Faculty of Engineering, Ain Shams University, 1 El-Sarayat St., Abbasia, 11517 Cairo (Egypt); El-Saadany, Ehab F.; Salama, Magdy M.A. [Electrical and Computer Engineering Dept., University of Waterloo, 200 University Avenue West, Waterloo, ON (Canada)

    2010-03-15

    In this paper a digital signal processor (DSP) based real time voltage envelope tracking system is developed and examined. The ADAptive LINEar neuron (ADALINE) and the Recursive Least Square (RLS) algorithms are adopted for envelope tracking. The proposed ADALINE and RLS algorithms give accurate results even under rapid dynamic changes. The paper investigates the effects of different parameters on the performance of the ADALINE algorithm and that of the RLS algorithm. The experimental system is cantered around a Texas Instrument 16 bit fixed-point arithmetic (TMS320LF2407A) evaluation board. Both the ADALINE and the RLS tracking algorithms are developed using the DSP-assembly language. A simple voltage flicker generator is implemented to produce various voltage disturbances. Extensive tests of the proposed envelope tracking algorithms are conducted to evaluate their dynamic performance. (author)

  1. Process, Voltage and Temperature Compensation Technique for Cascode Modulated PAs

    DEFF Research Database (Denmark)

    Sira, Daniel; Larsen, Torben

    2013-01-01

    This paper presents a process, voltage and temperature (PVT) compensation method for a cascode modulated polar power amplifier (PA). It is shown that it is possible to create a baseband replica circuit of the PA that has the same AM-AM nonlinearity as the PA itself. The replica circuit, that repr......This paper presents a process, voltage and temperature (PVT) compensation method for a cascode modulated polar power amplifier (PA). It is shown that it is possible to create a baseband replica circuit of the PA that has the same AM-AM nonlinearity as the PA itself. The replica circuit...

  2. 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.

  3. 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...

  4. 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...

  5. High-Mixed-Voltage Analog and RF Circuit Techniques for Nanoscale CMOS

    CERN Document Server

    Mak, Pui-In

    2012-01-01

    This book presents high-/mixed-voltage analog and radio frequency (RF) circuit techniques for developing low-cost multistandard wireless receivers in nm-length CMOS processes.  Key benefits of high-/mixed-voltage RF and analog CMOS circuits are explained, state-of-the-art examples are studied, and circuit solutions before and after voltage-conscious design are compared. Three real design examples are included, which demonstrate the feasibility of high-/mixed-voltage circuit techniques.    Provides a valuable summary and real case studies of the state-of-the-art in high-/mixed-voltage circuits and systems; Includes novel high-/mixed-voltage analog and RF circuit techniques – from concept to practice; Describes the first high-voltage-enabled mobile-TVRF front-end in 90nm CMOS and the first mixed-voltage full-band mobile-TV Receiver in 65nm CMOS; Demonstrates the feasibility of high-/mixed-voltage circuit techniques with real design examples.  

  6. Gain variation induced by power transient in thulium-doped fiber amplifier at 2 μm and its reduction by optical gain clamping technique

    Science.gov (United States)

    Khamis, M. A.; Ennser, K.

    2017-02-01

    This paper investigates the dynamic behavior of a thulium doped fiber amplifier (TDFA) operating in the 2 μm region for reconfigurable wavelength division multiplexing (WDM) systems. We show deleterious channel power fluctuations may be generated by input power variation at the amplifier and we propose the use of an optical gain-clamping technique. The investigated system consists of 20 channels with -4 dBm total input power. Our findings revealed that the effects of power transients due to channel reconfigurations are significantly reduced by a lasing feedback signal. Simulation results show that a power excursion of 4.3 dB is produced after dropping 19 channels when the amplifier gain is unclamped and only 0.0062 dB when the amplifier gain is clamped. The dynamics of GC-TDFA are mainly influenced by the value of the pump power factor and thus the laser signal achieves a stronger stabilization condition with increasing pump power factor. Hence, optical gain clamping is a simple and robust technique to control the power transient in the thulium-doped fiber amplifier of WDM systems at 2 μm.

  7. High voltage magnetic pulse generation using capacitor discharge technique

    Directory of Open Access Journals (Sweden)

    M. Rezal

    2014-12-01

    Full Text Available A high voltage magnetic pulse is designed by applying an electrical pulse to the coil. Capacitor banks are developed to generate the pulse current. Switching circuit consisting of Double Pole Double Throw (DPDT switches, thyristor, and triggering circuit is developed and tested. The coil current is measured using a Hall-effect current sensor. The magnetic pulse generated is measured and tabulated in a graph. Simulation using Finite Element Method Magnetics (FEMM is done to compare the results obtained between experiment and simulation. Results show that increasing the capacitance of the capacitor bank will increase the output voltage. This technology can be applied to areas such as medical equipment, measurement instrument, and military equipment.

  8. A meta-analysis comparing the outcomes of LigaSure Small Jaw versus clamp-and-tie technique or Harmonic Focus Scalpel in thyroidectomy

    Science.gov (United States)

    Zhang, Lei; Li, Namei; Yang, Xuemei; Chen, Jie

    2017-01-01

    Abstract Background: LigaSure (LS) Small Jaw is a surgical hemostasis equipment that is newly introduced in thyroid surgery. The objective of this study is to assess the short-term efficacy and safety outcomes of LS Small Jaw compared with clamp-and-tie technique or Harmonic Focus Scalpel in thyroidectomy. Methods: A literature search was performed in the PubMed and Embase databases (until June 12, 2016) that reported the comparisons between LS Small Jaw and other techniques in thyroidectomy. Quality assessments were performed according to The Cochrane Collaboration's risk of bias tool and a modification of the Newcastle-Ottawa Scale in randomized controlled trials (RCTs) and non-RCTs, respectively. All statistical analyses were conducted using RevMan 5.3. Results: Finally, 7 studies with 813 patients were included into the meta-analysis, and all included studies were comparable with moderate-to-high quality. There was significant reduced operative time in LS Small Jaw, compared with clamp-and-tie (mean difference [MD] = −17.49, 95% confidence interval [CI]: −22.20 to 12.77, P < 0.00001) or Harmonic Focus Scalpel (MD = −2.29, 95% CI: −3.19 to 1.39, P < 0.00001). Besides, other perioperative outcomes including intraoperative blood loss and postoperative blood loss favored LS Small Jaw compared with clamp-and-tie. In terms of complications, less-temporary hypocalcemia rate was observed in LS Small Jaw compared with clamp-and-tie (odds ratio [OR] = 0.49, 95% CI: 0.27–0.90, P = 0.02), although no significant difference was detected compared with Harmonic Focus Scalpel (OR = 0.47, 95% CI: 0.14–1.56, P = 0.22). Other complications such as length of hospital stay, permanent hypocalcemia, temporary or permanent recurrent laryngeal nerve palsy, and hematomas were not significant. Conclusion: In conclusion, LS Small Jaw is more favorable than clamp-and-tie technique or Harmonic Focus Scalpel in thyroidectomy. PMID:28296728

  9. Automated patch-clamp technique: increased throughput in functional characterization and in pharmacological screening of small-conductance Ca2+ release-activated Ca2+ channels.

    Science.gov (United States)

    Schrøder, Rikke L; Friis, Søren; Sunesen, Morten; Mathes, Chris; Willumsen, Niels J

    2008-08-01

    The suitability of an automated patch clamp for the characterization and pharmacological screening of calcium release-activated calcium (CRAC) channels endogenously expressed in RBL-2H3 cells was explored with the QPatch system. CRAC currents (I( CRAC)) are small, and thus precise recordings require high signal-to-noise ratios obtained by high seal resistances. Automated whole-cell establishment resulted in membrane resistances of 1728 +/- 226 MOmega (n = 44). CRAC channels were activated by a number of methods that raise intracellular calcium concentration, including EGTA, ionomycin, Ins(1,4,5)P3, and thapsigargin. I(CRAC) whole-cell currents ranged from 30 to 120 pA with rise times of 40 to 150 s. An initial delay in current activation was observed in particular when I(CRAC) was activated by passive store depletion using EGTA. Apparent rundown of I(CRAC) was commonly observed, and the current could be reactivated by subsequent addition of thapsigargin. I(CRAC) was blocked by SKF-96365 and 2-APB with IC50 values of 4.7 +/- 1.1 microM (n = 9) and 7.5 +/- 0.7 (n = 9) microM, respectively. The potencies of these blockers were similar to values reported for I(CRAC) in similar conventional patch-clamp experiments. The study demonstrates that CRAC channels can be rapidly and efficiently targeted with automated patch-clamp techniques for characterization of physiological and pharmacological properties.

  10. Performance of two modified optimization techniques for power system voltage stability problems

    Directory of Open Access Journals (Sweden)

    S. Harish Kiran

    2016-09-01

    Full Text Available The development of optimization techniques in power system is to determine the sizing of Flexible AC Transmission System (FACTS devices such as Unified Power Flow Series Compensator (UPFC controller in improving the voltage stability and bus voltage margin. An attempt is made to modify the Particle Swarm Optimization (PSO and Artificial Bee Colony (ABC with Hybrid-Genetic Algorithm (H-GA for determination of sizing of the device. Fast Voltage Stability Index (FVSI is used to identify the location of the device to be connected. The proposed methods are implemented in IEEE 30 Bus system and its results are tabulated for each technique.

  11. Techniques for detecting proximity to voltage collapse in AC/DC systems

    Energy Technology Data Exchange (ETDEWEB)

    Canizares, Claudio A. [Escuela Politecnica Nacional, Quito (Ecuador); Long, Willis F.; Alvarado, Fernando L.; DeMarco, CChristopher L. [Wisconsin Univ., Madison, WI (United States)

    1992-12-31

    This paper describes three different techniques to detect proximity to voltage collapse (saddle-node bifurcation) in AC/DC systems; namely, direct (point of collapse) methods, continuation methods, and transient energy function methods. These techniques are compared among them, and also against the voltage sensitivity factor method using a 173 bus ac/dc test system. Various operational conditions are considered for this test system, so that transfer capabilities between areas and the effects of HVDC links can be analysed from the point of view of voltage collapse. 24 refs., 7 figs.

  12. 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...

  13. A Hybrid Islanding Detection Technique Using Average Rate of Voltage Change and Real Power Shift

    DEFF Research Database (Denmark)

    Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

    2009-01-01

    technique is proposed to solve this problem. An average rate of voltage change (passive technique) has been used to initiate a real power shift (active technique), which changes the eal power of distributed generation (DG), when the passive technique cannot have a clear discrimination between islanding......The mainly used islanding detection techniques may be classified as active and passive techniques. Passive techniques don't perturb the system but they have larger nondetection znes, whereas active techniques have smaller nondetection zones but they perturb the system. In this paper, a new hybrid...

  14. A test technique for measuring lightning-induced voltages on aircraft electrical circuits

    Science.gov (United States)

    Walko, L. C.

    1974-01-01

    The development of a test technique used for the measurement of lightning-induced voltages in the electrical circuits of a complete aircraft is described. The resultant technique utilizes a portable device known as a transient analyzer capable of generating unidirectional current impulses similar to lightning current surges, but at a lower current level. A linear relationship between the magnitude of lightning current and the magnitude of induced voltage permitted the scaling up of measured induced values to full threat levels. The test technique was found to be practical when used on a complete aircraft.

  15. 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.

  16. 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%.

  17. 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.

  18. A new curvature compensation technique for CMOS voltage reference using |VGS| and ΔVBE

    Science.gov (United States)

    Xuemin, Li; Mao, Ye; Gongyuan, Zhao; Yun, Zhang; Yiqiang, Zhao

    2016-05-01

    A new mixed curvature compensation technique for CMOS voltage reference is presented, which resorts to two sub-references with complementary temperature characteristics. The first sub-reference is the source-gate voltage |VGS|p of a PMOS transistor working in the saturated region. The second sub-reference is the weighted sum of gate-source voltages |VGS|n of NMOS transistors in the subthreshold region and the difference between two base-emitter voltages ΔVBE of bipolar junction transistors (BJTs). The voltage reference implemented utilizing the proposed curvature compensation technique exhibits a low temperature coefficient and occupies a small silicon area. The proposed technique was verified in 0.18 μm standard CMOS process technology. The performance of the circuit has been measured. The measured results show a temperature coefficient as low as 12.7 ppm/°C without trimming, over a temperature range from -40 to 120 °C, and the current consumption is 50 μA at room temperature. The measured power-supply rejection ratio (PSRR) is -31.2 dB @ 100 kHz. The circuit occupies an area of 0.045 mm2. Project supported by the National Natural Science Foundation of China (No. 61376032).

  19. Voltage Stabilization of a Wind Turbine with STATCOM Using Intelligent Control Techniques

    Directory of Open Access Journals (Sweden)

    S. A. Gawish

    2016-03-01

    Full Text Available Application of FACTS controller called Static Synchronous Compensator STATCOM to improve the performance of power grid with Wind System is investigated. The essential feature of the STATCOM is that it has the ability to absorb or inject fastly reactive power with power grid. Therefore the voltage regulation of the power grid with STATCOM FACTS device is achieved. Moreover restoring the stability of the wind system at suddenly step up or down in wind speed is obtained with STATCOM. This paper describes a complete simulation of voltage regulation of a wind system using STATCOM. Conventional control technique as proportional plus integral controller , and intelligent techniques as FLC and ANFIS are used in this work. The control technique is performed using MATLAB package software. The dynamic response of uncontrolled system is also investigated under wide range of disturbances. The voltage regulation by using STATCOM whose output is varied so as to maintain or control output voltage in the system. The dynamic response of controlled system is shown and comparison between the uncontrolled system and the controlled system is described to assure the validity of the proposed controller. Also comparison between the proposed control methods scheme is presented. To validate the powerful of the STATCOM FACTS controllers, the studied power system is simulated and subjected to different severe disturbances. The results prove the effectiveness of the proposed STATCOM controller in terms of fast damping the power system oscillations and restoring the power system stability and voltage.

  20. Bottom-series coupled quadrature VCO using the inductive gate voltage boosting technique

    Science.gov (United States)

    Jang, Sheng-Lyang; Chou, Li-Te

    2013-09-01

    This article presents a new low-voltage bottom-series coupled quadrature voltage-controlled oscillator (QVCO), which consists of two n-core cross-coupled VCOs with the bottom-series coupling transistors. The low-voltage operation is obtained via an inductive gate voltage boosting technique. The proposed CMOS QVCO has been implemented with the TSMC 0.18 µm CMOS technology and the die area is 0.897 × 0.767 mm2. At the supply voltage of 0.7 V, the total power consumption is 1.5 mW. The free-running frequency of the QVCO is tuneable from 3.77 to 4.12 GHz as the tuning voltage is varied from 0.0 to 0.7 V. The measured phase noise at 1 MHz frequency offset is -123.35 dBc/Hz at the oscillation frequency of 4.12 GHz and the figure of merit of the proposed QVCO is -193.5 dBc/Hz.

  1. Harmonic elimination technique for a single-phase multilevel converter with unequal DC link voltage levels

    DEFF Research Database (Denmark)

    Ghasemi, N.; Zare, F.; Boora, A.A.

    2012-01-01

    on the output voltage quality by reducing its total harmonic distortion, which must take into consideration for some applications such as uninterruptable power supply, motor drive systems and piezoelectric transducer excitation. In order to verify the proposed modulation technique, MATLAB simulations...

  2. A zero-voltage switching technique for minimizing the current-source power of implanted stimulators.

    Science.gov (United States)

    Çilingiroğlu, Uğur; İpek, Sercan

    2013-08-01

    The current-source power of an implanted stimulator is reduced almost to the theoretical minimum by driving the electrodes directly from the secondary port of the inductive link with a dedicated zero-voltage switching power supply. A feedback loop confined to the secondary of the inductive link adjusts the timing and conduction angle of switching to provide just the right amount of supply voltage needed for keeping the current-source voltage constant at or slightly above the compliance limit. Since drive is based on current rather than voltage, and supply-voltage update is near real-time, the quality of the current pulses is high regardless of how the electrode impedance evolves during stimulation. By scaling the switching frequency according to power demand, the technique further improves overall power consumption of the stimulator. The technique is implemented with a very simple control circuitry comprising a comparator, a Schmitt trigger and a logic gate of seven devices in addition to an on-chip switch and an off-chip capacitor. The power consumed by the proposed supply circuit itself is no larger than what the linear regulator of a conventional supply typically consumes for the same stimulation current. Still, the sum of supply and current-source power is typically between 20% and 75% of the conventional source power alone. Functionality of the proposed driver is verified experimentally on a proof-of-concept prototype built with 3.3 V devices in a 0.18 μm CMOS technology.

  3. ZnO films deposited by optimized PLD technique with bias voltages

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Hiroyuki; Shitara, Tamae; Komiyama, Takao; Chonan, Yasunori; Aoyama, Takashi [Department of Electronics and Information Systems, Akita Prefectural University, 84-4 Tsuchiya Ebinokuchi, 015-0055 Yuri-Honjo (Japan)

    2010-02-15

    The pulsed laser deposition (PLD) technique with bias voltage application for formation of high quality ZnO films was investigated. Oxygen ambient in the PLD chamber significantly decreased the photoluminescence (PL) intensity of near band edge (NBE) emission. Then, instead of using oxygen ambient, the PLD technique with bias voltage application was optimized to attain the stoichiometric composition of the ZnO films. As the deposition temperature was increased, the X-ray spectrum width diffracted from the (0002) planes was decreased and it showed a minimum value at 700 C. The PL intensity of the NBE emission also had its maximum value for the film deposited at 700 C. For the ZnO films deposited at 700 C, the X-ray spectrum width showed the minimum value under a bias voltage of -50 V. The PL intensity of the NBE emission also had a maximum value under the same bias voltage. Thus, ZnO films deposited under a bias voltage of -50 V at 700 C had strong NBE emission intensities. These results could be explained not only by attaining the stoichiometric composition of the ZnO film but also by decreasing the number of high energy O{sup 2-} ions which caused non-radiative recombination centers in the film. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. A non-invasive technique for measuring the electroencephalogram of broiler chickens in a fast way: the 'chicken EEG clamp' (CHEC)

    NARCIS (Netherlands)

    Coenen, A.M.L.; Prinz, S.; Oijen, G.B.M. van; Bessei, W.

    2007-01-01

    A device was developed to measure in a fast way the electroencephalogram (EEG) of broiler chickens in a non-invasive way. The 'chicken EEG clamp' (CHEC) consists of a framework with two pointed electrodes, fitting as a clamp around the chicken's head. The EEG is recorded by the two active electrodes

  9. 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.

  10. High impulse voltage and current measurement techniques fundamentals, measuring instruments, measuring methods

    CERN Document Server

    Schon, Klaus

    2013-01-01

    Equipment to be installed in electric power-transmission and distribution systems must pass acceptance tests with standardized high-voltage or high-current test impulses which simulate the stress on the insulation caused by external lightning discharges and switching operations in the grid. High impulse voltages and currents are also used in many other fields of science and engineering for various applications. Therefore, precise impulse-measurement techniques are necessary, either to prevent an over- or understressing of the insulation or to guarantee the effectiveness and quality of the application. The book deals with: principal generator circuits for generating high-voltage and high-current impulses measuring systems and their calibration according to IEC 60060 and IEC 62475 methods of estimating uncertainties of measurement mathematical and experimental basis for characterizing the transfer behavior of spatially extended systems used for measuring fast transients. This book is intended for engineers and ...

  11. A novel method of teaching surgical techniques to residents--computerized enhanced visual learning (CEVL) with simulation to certify mastery of training: a model using newborn clamp circumcision.

    Science.gov (United States)

    Smith, Angela; Maizels, Max; Korets, Ruslan; Wiener, John S; Stiener, Michael; Liu, Dennis B; Sutherland, Richard W

    2013-12-01

    To assess the learning process of combining a web-based video of a simulated surgical procedure with a step-by-step checklist of the same procedure in achieving competency of the simulated technique, in this case a newborn clamp circumcision. Fundamental to this particular learning process is immediate mentor step-by-step feedback which specifically follows the procedure's step-by-step checklist. Pediatric residents naïve to newborn circumcision were enrolled (n = 7). A circumcision simulator, instruments, and web access to the learning module were provided. Residents trained independently and then performed two simulations with the mentor. The first simulation was completed with formative scored feedback. The learner then performed a second scored simulation. All learners showed improvement between the first and second simulation (mean 85.3-97.4). All residents achieved competency (96/100 or greater) by the second simulation. On post-procedure surveys, learners demonstrated increased comfort and reduced apprehension in performing the procedure. Combining a web-accessible video of a procedure, a checklist, and a simulator followed by a single mentor session with immediate formative feedback which follows the steps of the checklist is a useful method to teach the simulation technique of circumcision. We plan to study if this paradigm is transferable to clinical circumcision. Copyright © 2013 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

  12. Efficiency Optimization by Considering the High Voltage Flyback Transformer Parasitics using an Automatic Winding Layout Technique

    DEFF Research Database (Denmark)

    Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe;

    2015-01-01

    .The energy efficiency is optimized using a proposed new automatic winding layout (AWL) technique and a comprehensive loss model.The AWL technique generates a large number of transformer winding layouts.The transformer parasitics such as dc resistance, leakage inductance and self-capacitance are calculated...... for each winding layout.An optimization technique is formulated to minimize the sum of energy losses during charge and discharge operations.The efficiency and energy loss distribution results from the optimization routine provide a deep insight into the high voltage transformer designand its impact...

  13. Low-Voltage Process-Compensated VCO with On-Chip Process Monitoring and Body-Biasing Circuit Techniques

    OpenAIRE

    Ueno, Ken; Hirose, Tetsuya; Asai, Tetsuya; Amemiya, Yoshihito

    2009-01-01

    A voltage-controlled oscillator (VCO) tolerant to process variations at lower supply voltage was proposed. The circuit consists of an on-chip threshold-voltage-monitoring circuit, a current-source circuit, a body-biasing control circuit, and the delay cells of the VCO. Because variations in low-voltage VCO frequency are mainly determined by that of the current in delay cells. a current-compensation technique was adopted by using an on-chip threshold-voltage-monitoring circuit and body-biasing...

  14. 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...

  15. 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.

  16. Low voltage integrated optics electro-optical modulator applied to optical voltage transformer based on WLI technique

    Science.gov (United States)

    Santos, J. C.; Rubini, J.; Silva, L. P. C.; Caetano, R. E.

    2015-09-01

    The use of two electro-optical modulators linked in series, one for sensing and one for recovering signals, was formerly presented by some of the authors as a solution for interrogation of optical fiber sensor systems based on WLI method. A key feature required from such systems is that half-wave voltage (Vπ) of recovering modulator must be as small as possible. Aiming at meeting this requirement, in this paper it is presented the use of an unbalanced Michelson Interferometer implemented using an integrated optics component as recover interferometer in an optical voltage transformer intended for high voltage measurements.

  17. Simulation Investigation of SPWM, THIPWM and SVPWM Techniques for Three Phase Voltage Source Inverter

    Directory of Open Access Journals (Sweden)

    Zulkifilie Bin Ibrahim

    2014-03-01

    Full Text Available Pulse width modulation (PWM technique is one of the vital issues for power electronic circuit control. A number of Pulse width modulation (PWM techniques are increasingly applied in many new industrial applications that require superior performance. The most widely applied PWM technique for three-phase voltage source inverters are Sine Pulse Width Modulation (SPWM, Third Harmonic Injection Pulse Width Modulation (THIPWM 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 switching frequency and not capable in over modulation region. THIPWM and SVPWM both provide better THD compared to SPWM. SVPWM shows lower THD in over modulation region and in high frequency application compared to THIPWM. These three techniques are discussed, analyzed and compared in terms of modulation index, switching frequency and inverter input voltage in this paper. The modeling and simulation for all PWM techniques have been done by using MATLAB/SIMULINK and Origin 6.1. From the simulation results, SVPWM shows the best performance and meet IEEE 519 standard of current harmonics level.

  18. Radial wedge flange clamp

    Science.gov (United States)

    Smith, Karl H.

    2002-01-01

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

  19. 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. 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...

  1. Dragon-I injector based on the induction voltage adder technique

    Directory of Open Access Journals (Sweden)

    Zhang Kaizhi

    2006-08-01

    Full Text Available The Dragon-I injector based on the induction voltage adder technique is introduced. Twelve ferrite loaded induction cells are connected in a series through central conducting stalks to achieve a pulsed voltage higher than 3.5 MV across the diode. Electrons are extracted from the velvet emitter and guided through the anode pipe by the magnets placed inside the cathode and anode shrouds. Measurements at the exit of injector show that, with an electric field of 200  kV/cm near the velvet surface and suitable magnetic field distribution, an electron beam up to 2.8 kA can be obtained with a normalized emittance of 1040π   mm mrad, and energy spread of 2.1% (3σ around the central energy of 3.5 MeV.

  2. Targeted Endovascular Temporary Vessel Occlusion with a Reverse Thermosensitive Polymer for Near-Bloodless Partial Nephrectomy: Comparison to Standard Surgical Clamping Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Flacke, Sebastian, E-mail: Sebastian.Flacke@lahey.org [Lahey Clinic, Tuft University Medical School, Department of Radiology (United States); Harty, Niall J.; Laskey, Daniel H.; Moinzadeh, Alireza [Lahey Clinic, Tuft University Medical School, Department of Urology (United States); Benn, James A. [Pluromed Inc (United States); Villani, Rosanna [DaVinci Biomedical Research Products (United States); Kalra, Aarti [Lahey Clinic, Tuft University Medical School, Department of Pathology (United States); Libertino, John A.; Madras, Peter N. [Lahey Clinic, Tuft University Medical School, Department of Urology (United States)

    2012-10-15

    Purpose: To determine whether reversible blood flow interruption to a randomly chosen target region of the kidney may be achieved with the injection of a reverse thermoplastic polymer through an angiographic catheter, thereby facilitating partial nephrectomy without compromising blood flow to the remaining kidney or adding risks beyond those encountered by the use of hilar clamping. Methods: Fifteen pigs underwent partial nephrectomy after blood flow interruption by vascular cross-clamping or injection of polymer (Lumagel Trade-Mark-Sign ) into a segmental artery. Five animals were euthanized after surgery (three open and two laparoscopic resection, cross-clamping n = 2), and 10 (open resection, cross-clamping n = 4) were euthanized after 6 weeks' survival. Blood specimens were obtained periodically, and angiogram and necropsy were performed at 6 weeks. Results: Selective renal ischemia was achieved in all cases. Surgical resection time averaged 9 and 24.5 min in the open and laparoscopic groups, respectively. Estimated blood loss was negligible with the exception of one case where an accessory renal artery was originally overlooked. Reversal of the polymer to a liquid state was consistent angiographically and visually in all cases. Time to complete flow return averaged 7.4 and 2 min for polymer and clamping, respectively. Angiography at 6 weeks revealed no evidence of vascular injury. Laboratory data and necropsies revealed no differences between animals undergoing vascular clamping or polymer injection. Conclusion: Lumagel was as effective as vascular clamping in producing a near bloodless operative field for partial nephrectomy while maintaining flow to the uninvolved portion of the affected kidney.

  3. 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 ...

  4. Analysis of cutting-edge techniques in the high voltage and high power adjustable speed drive systems

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The high voltage and high power adjustable speed drive (ASD) system is one of the most attractive fields in power electronics, and it is also a very crucial technique for energy saving and emission reduction. This paper discussed and analyzed the main cutting-edge knowledge and issues in the process of exploiting the high voltage and high power ASD system.

  5. 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

  6. 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...

  7. Sizing of SRAM Cell with Voltage Biasing Techniques for Reliability Enhancement of Memory and PUF Functions

    Directory of Open Access Journals (Sweden)

    Chip-Hong Chang

    2016-08-01

    Full Text Available Static Random Access Memory (SRAM has recently been developed into a physical unclonable function (PUF for generating chip-unique signatures for hardware cryptography. The most compelling issue in designing a good SRAM-based PUF (SPUF is that while maximizing the mismatches between the transistors in the cross-coupled inverters improves the quality of the SPUF, this ironically also gives rise to increased memory read/write failures. For this reason, the memory cells of existing SPUFs cannot be reused as storage elements, which increases the overheads of cryptographic system where long signatures and high-density storage are both required. This paper presents a novel design methodology for dual-mode SRAM cell optimization. The design conflicts are resolved by using word-line voltage modulation, dynamic voltage scaling, negative bit-line and adaptive body bias techniques to compensate for reliability degradation due to transistor downsizing. The augmented circuit-level techniques expand the design space to achieve a good solution to fulfill several otherwise contradicting key design qualities for both modes of operation, as evinced by our statistical analysis and simulation results based on complementary metal–oxide–semiconductor (CMOS 45 nm bulk Predictive Technology Model.

  8. A Low Phase Noise CMOS Quadrature Voltage Control Oscillator Using Clock Gated Technique

    Directory of Open Access Journals (Sweden)

    Jothi Baskar A

    2015-06-01

    Full Text Available This project presents the low phase noise cmos quadrature voltage control oscillator using clock gating technique. Here the colpitts vco is used to split the capacitance in the Qvco circuit producing quadrature output. The startup condition in the oscillator is improved by using enhancement [12].This QVCO performs the operation anti phase injection locking fordevice reuse [8]. The new clock gating technique is used to reduce the power with thepower supply 1.5v. The QVCO uses a 0.5mwith phase error of 0.4 and exhibits a phase noise of -118dBc/HZ at 1MHZ offset at the centre frequency of 500MHZ. Index terms: current switching, clock gating, phase noise, Qvco

  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. 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.

  11. 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

  12. 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.

  13. Pixel-level A/D conversion using voltage reset technique

    Institute of Scientific and Technical Information of China (English)

    Li Minzeng; Li Fule; Zhang Chun; Wang Zhihua

    2014-01-01

    This paper presents a 50 Hz 15-bit analog-to-digital converter (ADC) for pixel-level implementation in CMOS image sensors.The ADC is based on charge packets counting and adopts a voltage reset technique to inject charge packets.The core circuit for charge/pulse conversion is specially optimized for low power,low noise and small area.An experimental chip with ten pixel-level ADCs has been fabricated and tested for verification.The measurement result shows a standard deviation of 1.8 LSB for full-scale output.The ADC has an area of 45 × 45μm2 and consumes less than 2 μW in a standard 1P-6M 0.18μm CMOS process.

  14. An exploding foil shockwave technique for magnetic flux compression and high voltage pulse generation

    CERN Document Server

    Goh, S E

    2002-01-01

    This thesis describes a novel electromagnetic shockwave technique for use in compressing magnetic flux and to serve as the basis for a new approach to producing fast-rising voltage pulses with amplitudes of several hundred kV. The shockwave is produced by an exploding foil driven electric gun that accelerates a Mylar flyer to impact with a sample of aluminium powder. Both Japanese and Russian researchers have previously published experimental results for shockwave magnetic flux compression using an explosive driver. The present research considers replacing the explosive energy of this driver by the electrostatic energy stored in a capacitor bank, thereby enabling experiments to be performed in a laboratory environment. Differences in performance that arise from the use of explosive and electrical driver are examined. A conventional electric gun system in planar geometry is developed to study the insulator-to-metallic transition in shock-compressed aluminium powder. This provides data on the conducting shock f...

  15. Analysis of cutting-edge techniques in the high voltage and high power adjustable speed drive systems

    Institute of Scientific and Technical Information of China (English)

    ZHAO ZhengMing; BAI Hua; YUAN LiQiang

    2009-01-01

    The high voltage and high power adjustable speed drive (ASD) system is one of the most attractive fields in power electronics, and it is also a very crucial technique for energy saving and emission re-duction. This paper discussed and analyzed the main cutting-edge knowledge and issues in the proc-ess of exploiting the high voltage and high power ASD system.

  16. A Survey of Non-conventional Techniques for Low-voltage Low-power Analog Circuit Design

    Directory of Open Access Journals (Sweden)

    F. Khateb

    2013-06-01

    Full Text Available Designing integrated circuits able to work under low-voltage (LV low-power (LP condition is currently undergoing a very considerable boom. Reducing voltage supply and power consumption of integrated circuits is crucial factor since in general it ensures the device reliability, prevents overheating of the circuits and in particular prolongs the operation period for battery powered devices. Recently, non-conventional techniques i.e. bulk-driven (BD, floating-gate (FG and quasi-floating-gate (QFG techniques have been proposed as powerful ways to reduce the design complexity and push the voltage supply towards threshold voltage of the MOS transistors (MOST. Therefore, this paper presents the operation principle, the advantages and disadvantages of each of these techniques, enabling circuit designers to choose the proper design technique based on application requirements. As an example of application three operational transconductance amplifiers (OTA base on these non-conventional techniques are presented, the voltage supply is only ±0.4 V and the power consumption is 23.5 µW. PSpice simulation results using the 0.18 µm CMOS technology from TSMC are included to verify the design functionality and correspondence with theory.

  17. 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.

  18. 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.

  19. Fingerprint technique for medium voltage relays and breakers makes maintenance superfluous; Fingerprint techniek maakt onnodig onderhoud overbodig

    Energy Technology Data Exchange (ETDEWEB)

    Krikke, K.; Peters, J.C.F.M. [Kenniscentrum Distributie Technologie KDT, PNEM, Den Bosch (Netherlands); Wilde, M. [Radiodetection Ltd., `s Heerenberg (Netherlands)

    1996-09-01

    The title technique will enable electric utilities to introduce condition based maintenance, improving quality and maintenance efficiency on the medium voltage network, giving the largest contribution to outages. The measurement equipment is developed by Kelman Ltd., based on an idea from an innovation project at one of the Dutch electric utility companies (PNEM). 6 figs., 6 refs.

  20. Dynamic Stability Improvement of Grid Connected DFIG Using Enhanced Field Oriented Control Technique for High Voltage Ride Through

    Directory of Open Access Journals (Sweden)

    V. N. Ananth Duggirala

    2015-01-01

    Full Text Available Doubly fed induction generator (DFIG is a better alternative to increased power demand. Modern grid regulations force DFIG to operate without losing synchronism during overvoltages called high voltage ride through (HVRT during grid faults. Enhanced field oriented control technique (EFOC was proposed in Rotor Side Control of DFIG converter to improve power flow transfer and to improve dynamic and transient stability. Further electromagnetic oscillations are damped, improved voltage mitigation and limit surge currents for sustained operation of DFIG during voltage swells. The proposed strategy has advantages such as improved reactive power control, better damping of electromagnetic torque oscillations, and improved continuity of voltage and current from stator and rotor to grid during disturbance. In EFOC technique, rotor flux reference changes its value from synchronous speed to zero during fault for injecting current at the rotor slip frequency. In this process, DC-Offset component of stator flux is controlled so that decomposition during overvoltage faults can be minimized. The offset decomposition of flux will be oscillatory in a conventional FOC, whereas in EFOC it is aimed to be quick damping. The system performance with overvoltage of 1.3 times, 1.62 times, and 2 times the rated voltage occurring is analyzed by using simulation studies.

  1. On the design of a low-voltage two-stage OTA using bulk-driven and positive feedback techniques

    Science.gov (United States)

    Khameh, Hassan; Shamsi, Hossein

    2012-09-01

    This article presents the design and simulation of a fully differential two-stage operational transconductance amplifier (OTA) in a 0.18 µm CMOS process with a 0.9 V supply voltage. For this purpose, both the bulk-driven and positive feedback techniques are employed. These techniques increase the DC gain by about 18.5 dB without consuming more power and changing the unity-gain bandwidth and phase margin of the OTA.

  2. 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.

  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. Percutaneous Lumbar Disc Clamp Technique in the Treatment of Lumbar Disc Herniation%经皮后路椎间盘钳夹术治疗腰椎间盘突出症

    Institute of Scientific and Technical Information of China (English)

    刘晓光; 杨建; 燕春山

    2015-01-01

    目的:探讨经皮后路椎间盘钳夹术治疗腰椎间盘突出症的疗效。方法对30例腰椎间盘突出症患者行经皮后路钳夹术治疗腰椎间盘突出症针对靶点治疗。结果30例患者均成功施行经皮后路椎间盘钳夹术。优24例,占80%;良2例,占6.67%;可2例,占6.67%;差2例,优良率93.33%。术后均未出现严重并发症。结论经皮后路椎间盘钳夹术能有效治疗腰椎间盘突出症。%Objective To investigate the therapeutic effect of percutaneous lumbar disc clamp technique in the treatment of lumbar disc herniation. Methods30 cases of lumbar disc herniation underwent percutaneous posterior forceps in treatment of lumbar disc herniation. Results30 patients had successful percutaneous lumbar disc clamp. Excellent in 24 cases, accounting for 80%;good in 2 cases, accounting for 6.67%; 2 cases, accounting for 6.67%; 2 cases of poor, good rate of 93.33%. There were no severe complications after operation.Conclusion Percutaneous lumbar disc clamp can be effective in the treatment of lumbar disc herniation.

  5. 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.

  6. 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

  7. 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.

  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. Method and apparatus for controlling LCL converters using asymmetric voltage cancellation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Hunter; Sealy, Kylee Devro; Sharp, Bryan Thomas; Gilchrist, Aaron

    2016-01-26

    A method and apparatus for LCL resonant converter control utilizing Asymmetric Voltage Cancellation is described. The methods to determine the optimal trajectory of the control variables are discussed. Practical implementations of sensing load parameters are included. Simple PI, PID and fuzzy logic controllers are included with AVC for achieving good transient response characteristics with output current regulation.

  11. Voltage-guided ablation technique for cavotricuspid isthmus-dependent atrial flutter

    DEFF Research Database (Denmark)

    Jacobsen, Peter K; Klein, George J; Gula, Lorne J

    2012-01-01

    with large amplitude atrial electrograms results in a highly efficient alternate method for the interruption of conduction across the cavotricuspid isthmus. Understanding the bundle structure of conduction over the isthmus facilitates more flexible approaches to its ablation and targeting maximum voltages...

  12. RF transconductor linearization technique robust to process, voltage and temperature variations

    NARCIS (Netherlands)

    Kundur Subramaniyan, Harish; Klumperink, Eric A.M.; Nauta, Bram; Venkatesh, Srinivasan; Kiaei, Ali

    2014-01-01

    A new reconfigurable linearized low noise transconductance amplifier (LNTA) design for a software-defined radio receiver is presented. The transconductor design aims at realizing high linearity at RF in a way that is robust for Process, Voltage and Temperature variations. It exploits resistive degen

  13. A Survey on Voltage Boosting Techniques for Step-Up DC-DC Converters

    DEFF Research Database (Denmark)

    Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Gorji, Saman Asghari;

    2016-01-01

    Step-up dc-dc converters are used to boost the voltage level of the input to a higher output level. Despite of its features such as simplicity of implementation, the fundamental boost dc-dc converter has shortcomings such as low boost ability and low power density. With these limitations, researc...

  14. BiasMDP: Carrier lifetime characterization technique with applied bias voltage

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Paul M., E-mail: paul.jordan@namlab.com; Simon, Daniel K.; Dirnstorfer, Ingo [Nanoelectronic Materials Laboratory gGmbH (NaMLab), Nöthnitzer Straße 64, 01187 Dresden (Germany); Mikolajick, Thomas [Nanoelectronic Materials Laboratory gGmbH (NaMLab), Nöthnitzer Straße 64, 01187 Dresden (Germany); Technische Universität Dresden, Institut für Halbleiter- und Mikrosystemtechnik, 01062 Dresden (Germany)

    2015-02-09

    A characterization method is presented, which determines fixed charge and interface defect densities in passivation layers. This method bases on a bias voltage applied to an electrode on top of the passivation layer. During a voltage sweep, the effective carrier lifetime is measured by means of microwave detected photoconductivity. When the external voltage compensates the electric field of the fixed charges, the lifetime drops to a minimum value. This minimum value correlates to the flat band voltage determined in reference impedance measurements. This correlation is measured on p-type silicon passivated by Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/HfO{sub 2} stacks with different fixed charge densities and layer thicknesses. Negative fixed charges with densities of 3.8 × 10{sup 12 }cm{sup −2} and 0.7 × 10{sup 12 }cm{sup −2} are determined for Al{sub 2}O{sub 3} layers without and with an ultra-thin HfO{sub 2} interface, respectively. The voltage and illumination dependencies of the effective carrier lifetime are simulated with Shockley Read Hall surface recombination at continuous defects with parabolic capture cross section distributions for electrons and holes. The best match with the measured data is achieved with a very low interface defect density of 1 × 10{sup 10 }eV{sup −1} cm{sup −2} for the Al{sub 2}O{sub 3} sample with HfO{sub 2} interface.

  15. Application of Patch-clamp Technique in Insect Toxin Action Mechanism%膜片钳技术在昆虫毒素作用机理研究中的应用

    Institute of Scientific and Technical Information of China (English)

    王瑞兰

    2013-01-01

    On the basis of introducing the function of patch-clamp technique and ion channel, the insecticide action mechanism (insect Na + channel toxin) was reviewed,as well as its application in new type safety insecticides development,which can provide reference for the research and development of insecticides.%在介绍膜片钳技术和离子通道的作用的基础上,综述了膜片钳技术在杀虫作用机理(昆虫Na+通道毒素)及新型安全生物杀虫剂研发中的应用,为新型安全生物杀虫剂的研发提供了参考.

  16. 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.

  17. Application of Locked Nucleic Acid (LNA) oligonucleotide-PCR clamping technique to selectively PCR amplify the SSU rRNA genes of bacteria in investigating the plant-associated community structures.

    Science.gov (United States)

    Ikenaga, Makoto; Sakai, Masao

    2014-09-17

    The simultaneous extraction of plant organelle (mitochondria and plastid) genes during the DNA extraction step is a major limitation in investigating the community structures of bacteria associated with plants because organelle SSU rRNA genes are easily amplified by PCR using primer sets that are specific to bacteria. To inhibit the amplification of organelle genes, the locked nucleic acid (LNA) oligonucleotide-PCR clamping technique was applied to selectively amplify bacterial SSU rRNA genes by PCR. LNA oligonucleotides, the sequences of which were complementary to mitochondria and plastid genes, were designed by overlapping a few bases with the annealing position of the bacterial primer and converting DNA bases into LNA bases specific to mitochondria and plastids at the shifted region from the 3' end of the primer-binding position. PCR with LNA oligonucleotides selectively amplified the bacterial genes while inhibited that of organelle genes. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that conventional amplification without LNA oligonucleotides predominantly generated DGGE bands from mitochondria and plastid genes with few bacterial bands. In contrast, additional bacterial bands were detected in DGGE patterns, the amplicons of which were prepared using LNA oligonucleotides. These results indicated that the detection of bacterial genes had been screened by the excessive amplification of the organelle genes. Sequencing of the bands newly detected by using LNA oligonucleotides revealed that their similarity to the known isolated bacteria was low, suggesting the potential to detect novel bacteria. Thus, application of the LNA oligonucleotide-PCR clamping technique was considered effective for the selective amplification of bacterial genes from extracted DNA containing plant organelle genes.

  18. 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

  19. PV Power-Generation System with a Phase-Shift PWM Technique for High Step-Up Voltage Applications

    Directory of Open Access Journals (Sweden)

    Cheng-Tao Tsai

    2012-01-01

    Full Text Available A PV power-generation system with a phase-shift pulse-width modulation (PWM technique for high step-up voltage applications is proposed. The proposed power-generation system consists of two stages. In the input stage, all power switches of the full-bridge converter with phase-shift technique can be operated with zero-current switching (ZCS at turn-on or turn-off transition. Hence, the switching losses of the power switches can be reduced. Then, in the DC output stage, a voltage-doubler circuit is used to boost a high dc-link bus voltage. To supply a utility power, a dc/ac inverter is connected to induce a sinusoidal source. In order to draw a maximum power from PV arrays source, a microcontroller is incorporated with the perturbation and observation method to implement maximum power point tracking (MPPT algorithm and power regulating scheme. In this study, a full load power of 300 W prototype has been built. Experimental results are presented to verify the performance and feasibility of the proposed PV power-generation system.

  20. Forward voltage short-pulse technique for measuring high power laser array junction temperature

    Science.gov (United States)

    Meadows, Byron L. (Inventor); Amzajerdian, Frazin (Inventor); Barnes, Bruce W. (Inventor); Baker, Nathaniel R. (Inventor)

    2012-01-01

    The present invention relates to a method of measuring the temperature of the P-N junction within the light-emitting region of a quasi-continuous-wave or pulsed semiconductor laser diode device. A series of relatively short and low current monitor pulses are applied to the laser diode in the period between the main drive current pulses necessary to cause the semiconductor to lase. At the sufficiently low current level of the monitor pulses, the laser diode device does not lase and behaves similar to an electronic diode. The voltage across the laser diode resulting from each of these low current monitor pulses is measured with a high degree of precision. The junction temperature is then determined from the measured junction voltage using their known linear relationship.

  1. FPGA techniques based new hybrid modulation strategies for voltage source inverters.

    Science.gov (United States)

    Sudha, L U; Baskaran, J; Elankurisil, S A

    2015-01-01

    This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results.

  2. Voltage-guided ablation technique for cavotricuspid isthmus-dependent atrial flutter: refining the continuous line.

    Science.gov (United States)

    Jacobsen, Peter K; Klein, George J; Gula, Lorne J; Krahn, Andrew D; Yee, Raymond; Leong-Sit, Peter; Mechulan, Alexis; Skanes, Allan C

    2012-06-01

    Ablation of the cavotricuspid isthmus has become first-line therapy for "isthmus-dependent" atrial flutter. The goal of ablation is to produce bidirectional cavotricuspid isthmus block. Traditionally, this has been obtained by creation of a complete ablation line across the isthmus from the ventricular end to the inferior vena cava. This article describes an alternative method used in our laboratory. There is substantial evidence that conduction across the isthmus occurs preferentially over discrete separate bundles of tissue. Consequently, voltage-guided ablation targeting only these bundles with large amplitude atrial electrograms results in a highly efficient alternate method for the interruption of conduction across the cavotricuspid isthmus. Understanding the bundle structure of conduction over the isthmus facilitates more flexible approaches to its ablation and targeting maximum voltages in our hands has resulted in reduction of ablation time and fewer recurrences.

  3. FPGA Techniques Based New Hybrid Modulation Strategies for Voltage Source Inverters

    OpenAIRE

    Sudha, L. U.; J. Baskaran; Elankurisil, S. A.

    2015-01-01

    This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switch...

  4. Complemenary body driving - a low voltage analog circuit technique for SOI

    Science.gov (United States)

    Mojarradi, M. M.; Terry, S.; Blalock, B. J.; Yong, L.; Dufrene, B.

    2002-01-01

    This paper describes several analog circuit primitives that utilize the body terminal as a signal port. A cascode current mirror that can operate with an input and output voltage of 200 mV; and a rail-to-rail, constant transconductance gain block capable of 1 V operation are presented. These circuits have been implemented in a standard 0.351 partially-depleted Silicon-on-Insulator (PDSOI) CMOS process and should find wide application in next-generation analog circuit designs.

  5. Impact of PLL Parameters Variation on the Pulsating Voltage Injection Technique Based PMSM Position Estimation at Low Speeds

    Directory of Open Access Journals (Sweden)

    Olfa Bel Hadj Brahim Kechiche

    2014-06-01

    Full Text Available This study highlights the impact of an universal Phase Locked Loop (PLL parameters variation on PMSM position estimation at low speeds. Indeed, the PLL parameters variation impact on the PMSM rotor position estimation performance and robustness cannot be neglected anymore. For this purpose, the study presents the theory and simulation results of a demodulation scheme applied to Sensorless PMSM control based on the Pulsating Voltage Injection (PVI technique. Comprehensive simulations, carried out under MATLAB/SIMULINK®, are discussed according to the variation of the PLL proportional and integral parameters.

  6. 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

  7. 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.

  8. 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.

  9. Differential voltage analyses of high-power, lithium-ion cells. 1. Technique and application

    Science.gov (United States)

    Bloom, Ira; Jansen, Andrew N.; Abraham, Daniel P.; Knuth, Jamie; Jones, Scott A.; Battaglia, Vincent S.; Henriksen, Gary L.

    The C/25 discharge data from 18650-size cells containing LiNi 0.8Co 0.1Al 0.1O 2 cathode and graphite anode laminates were analyzed through the use of the differential voltage, d V/d Q, curves. Using half-cell data, the peaks in the d V/d Q curve of the full cell data were assigned. Analysis of the relative peak shifts allowed for the determination of the source of capacity fade. For cells formed and aged at 45 °C for 40 weeks (capacity fade = 7.5%), the analysis indicated negligible loss of accessible material at the anode and at the cathode. Capacity loss of the cell could be accounted for, largely, by side reactions at the anode. This type of analysis can be used when the introduction of a reference electrode is difficult or impractical.

  10. Modulation Technique for Four-Leg Voltage Source Inverter without a Look-Up Table

    DEFF Research Database (Denmark)

    Ebrahimzadeh, Esmaeil; Farhangi, Shahrokh; Iman-Eini, Hossein

    2016-01-01

    , is calculated without need of a look-up table and complex equations. Applying the dead time by software is very straightforward in the proposed technique. In addition, by simplification of the proposed modulation technique, it can be applied to the three-leg inverters. Simulation results in PSCAD...

  11. 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.

  12. 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.

  13. Imaging fast calcium currents beyond the limitations of electrode techniques.

    Science.gov (United States)

    Jaafari, Nadia; De Waard, Michel; Canepari, Marco

    2014-09-16

    The current understanding of Ca(2+) channel function is derived from the use of the patch-clamp technique. In particular, the measurement of fast cellular Ca(2+) currents is routinely achieved using whole-cell voltage-clamp recordings. However, this experimental approach is not applicable to the study of local native Ca(2+) channels during physiological changes of membrane potential in complex cells, since the voltage-clamp configuration constrains the membrane potential to a given value. Here, we report for the first time to our knowledge that Ca(2+) currents from individual cells can be quantitatively measured beyond the limitations of the voltage-clamp approach using fast Ca(2+) imaging with low-affinity indicators. The optical measurement of the Ca(2+) current was correlated with the membrane potential, simultaneously measured with a voltage-sensitive dye to investigate the activation of Ca(2+) channels along the apical dendrite of the CA1 hippocampal pyramidal neuron during the back-propagation of an action potential. To validate the method, we analyzed the voltage dependence of high- and low-voltage-gated Ca(2+) channels. In particular, we measured the Ca(2+) current component mediated by T-type channels, and we investigated the mechanisms of recovery from inactivation of these channels. This method is expected to become a reference approach to investigate Ca(2+) channels in their native physiological environment.

  14. 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-....

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

    NARCIS (Netherlands)

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

    1997-01-01

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

  16. Robust Sequential Circuits Design Technique for Low Voltage and High Noise Scenarios

    Directory of Open Access Journals (Sweden)

    Garcia-Leyva Lancelot

    2016-01-01

    In this paper we introduce an innovative input and output data redundancy principle for sequential block circuits, the responsible to keep the state of the system, showing its efficiency in front of other robust technique approaches. The methodology is totally different from the Von Neumann approaches, because element are not replicated N times, but instead, they check the coherence of redundant input data no allowing data propagation in case of discrepancy. This mechanism does not require voting devices.

  17. Low-Power Circuit Techniques for Low-Voltage Pipelined ADCs Based on Switched-Opamp Architecture

    Science.gov (United States)

    Ou, Hsin-Hung; Chang, Soon-Jyh; Liu, Bin-Da

    This paper proposes useful circuit structures for achieving a low-voltage/low-power pipelined ADC based on switched-opamp architecture. First, a novel unity-feedback-factor sample-and-hold which manipulates the features of switched-opamp technique is presented. Second, opamp-sharing is merged into switched-opamp structure with a proposed dual-output opamp configuration. A 0.8-V, 9-bit, 10-Msample/s pipelined ADC is designed to verify the proposed circuit. Simulation results using a 0.18-μm CMOS 1P6M process demonstrate the figure-of-merit of this pipelined ADC is only 0.71pJ/step.

  18. Ultra low voltage and low power Static Random Access Memory design using average 6.5T technique

    Directory of Open Access Journals (Sweden)

    Nagalingam RAJESWARAN

    2015-12-01

    Full Text Available Power Stringent Static Random Access Memory (SRAM design is very much essential in embedded systems such as biomedical implants, automotive electronics and energy harvesting devices in which battery life, input power and execution delay are of main concern. With reduced supply voltage, SRAM cell design will go through severe stability issues. In this paper, we present a highly stable average nT SRAM cell for ultra-low power in 125nm technology. The distinct difference between the proposed technique and other conventional methods is about the data independent leakage in the read bit line which is achieved by newly introduced block mask transistors. An average 6.5T SRAM and average 8T SRAM are designed and compared with 6T SRAM, 8T SRAM, 9T SRAM, 10T SRAM and 14T SRAM cells. The result indicates that there is an appreciable decrease in power consumption and delay.

  19. 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 ...

  20. Isolation and culture of sinus node cells and identification of patch clamp technique in neonatal rabbits%乳兔窦房结细胞的分离及鉴定

    Institute of Scientific and Technical Information of China (English)

    刘如秀; 刘宇; 汪艳丽; 彭杰; 徐利亚

    2013-01-01

    Objective To summarize the isolation, purification, culture and identification of sinus node cells ( SNC ) in neonatal rabbits. Methods New Zealand neonatal rabbits ( n=5 ) were selected and from them SNC were digested and isolated by using dual anzymolysis. The isolated SNC were purified and cultured by using differential adherence combining 5-BrdU. The morphological changes of SNC were observed and action potential was recorded by using patch clamp technique. Results The morphological forms of cultured SNC were mainly spindle cells, triangular cells and irregular cells and fusiformis was the most with the fastest beating rate, which was accorded with the characteristics of SNC. Among action potential recorded from 10 spindle cells by patch clamp technique, the average maximum diastolic potential was ( -50.9 ± 5.3 ) mV and amplitude of action potential was ( 61.9 ±4.8 ) mV. Conclusion The active condition of SNC digested, isolated and purified by using dual enzymolysis, differential adherenc and 5-BrdU are quite good with typical action potential.%目的 乳兔窦房结细胞(sinus node cell,SNC)的分离、纯化、培养与鉴定.方法 选用新生新西兰乳兔5只,采用双酶解法对细胞进行消化分离,差速贴壁结合5-BrdU对分离的细胞进行纯化培养,观察SNC形态变化并采用全细胞膜片钳技术对SNC进行动作电位的记录.结果 培养得到的SNC主要有3种形态:梭形、三角形与不规则形,而梭形细胞最多,搏动频率最快,符合窦房结细胞的特征.采用膜片钳技术记录10个梭形细胞的动作电位中,平均最大舒张电位为(-50.9±5.3)mV,动作电位幅度为(61.9±4.8)mV.结论 采用双酶解、差速贴壁及BrdU对乳兔窦房结细胞进行消化、分离可得到纯化的SNC,此种方法得到的SNC状态活性良好,且具有典型特征的动作电位.

  1. Activation of Ih and TTX-sensitive sodium current at subthreshold voltages during CA1 pyramidal neuron firing.

    Science.gov (United States)

    Yamada-Hanff, Jason; Bean, Bruce P

    2015-10-01

    We used dynamic clamp and action potential clamp techniques to explore how currents carried by tetrodotoxin-sensitive sodium channels and HCN channels (Ih) regulate the behavior of CA1 pyramidal neurons at resting and subthreshold voltages. Recording from rat CA1 pyramidal neurons in hippocampal slices, we found that the apparent input resistance and membrane time constant were strongly affected by both conductances, with Ih acting to decrease apparent input resistance and time constant and sodium current acting to increase both. We found that both Ih and sodium current were active during subthreshold summation of artificial excitatory postsynaptic potentials (EPSPs) generated by dynamic clamp, with Ih dominating at less depolarized voltages and sodium current at more depolarized voltages. Subthreshold sodium current-which amplifies EPSPs-was most effectively recruited by rapid voltage changes, while Ih-which blunts EPSPs-was maximal for slow voltage changes. The combined effect is to selectively amplify rapid EPSPs. We did similar experiments in mouse CA1 pyramidal neurons, doing voltage-clamp experiments using experimental records of action potential firing of CA1 neurons previously recorded in awake, behaving animals as command voltages to quantify flow of Ih and sodium current at subthreshold voltages. Subthreshold sodium current was larger and subthreshold Ih was smaller in mouse neurons than in rat neurons. Overall, the results show opposing effects of subthreshold sodium current and Ih in regulating subthreshold behavior of CA1 neurons, with subthreshold sodium current prominent in both rat and mouse CA1 pyramidal neurons and additional regulation by Ih in rat neurons.

  2. 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.

  3. 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

  4. ZVZCS Based High Frequency Link Grid Connected SVM applied Three Phase Three Level Diode Clamped Inverter for Photovoltaic Applications Part-II

    Directory of Open Access Journals (Sweden)

    Soumyadeep Ray

    2014-07-01

    Full Text Available This article proposes a newly proposed highly effective Zero Voltage and Zero Current switching based Front end converter with a High Frequency Transformer with a Three Phase Three Level Diode Clamped Inverter in photovoltaic applications. The switching scheme is implemented in MATLAB/ Simulink condition. ZVZCS condition is achieved. This type of converter shows high efficiency and very negligible switching loss. Finally ZVZCS based High Frequency Link Diode Clamped Inverter is connected to Grid. An MCI optimized Current controller is used with SVM switching technique.  In This article, responses with three types of controllers (I, PI, PID have been examined and compared. Simulation results show the effectiveness, and validity of this technique.

  5. 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...

  6. 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)

  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. 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.

  10. 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.

  11. 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.

  12. 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 ...

  13. 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...

  14. A Low-Voltage Ride-Through Technique for Grid-Connected Converters with Reduced Power Transistors Stress

    DEFF Research Database (Denmark)

    Chen, Hsin-Chih; Lee, Chia-Tse; Cheng, Po-Tai

    2016-01-01

    With more and more distributed energy resources being installed in the utility grid, grid operators start imposing the low-voltage ride-through requirement on such systems to remain grid-connected and inject reactive and/or active current to support grid voltage during fault conditions. This pape...

  15. 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.

  16. 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.

  17. 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

  18. Characterization of voltage-gated Ca(2+ conductances in layer 5 neocortical pyramidal neurons from rats.

    Directory of Open Access Journals (Sweden)

    Mara Almog

    Full Text Available Neuronal voltage-gated Ca(2+ channels are involved in electrical signalling and in converting these signals into cytoplasmic calcium changes. One important function of voltage-gated Ca(2+ channels is generating regenerative dendritic Ca(2+ spikes. However, the Ca(2+ dependent mechanisms used to create these spikes are only partially understood. To start investigating this mechanism, we set out to kinetically and pharmacologically identify the sub-types of somatic voltage-gated Ca(2+ channels in pyramidal neurons from layer 5 of rat somatosensory cortex, using the nucleated configuration of the patch-clamp technique. The activation kinetics of the total Ba(2+ current revealed conductance activation only at medium and high voltages suggesting that T-type calcium channels were not present in the patches. Steady-state inactivation protocols in combination with pharmacology revealed the expression of R-type channels. Furthermore, pharmacological experiments identified 5 voltage-gated Ca(2+ channel sub-types - L-, N-, R- and P/Q-type. Finally, the activation of the Ca(2+ conductances was examined using physiologically derived voltage-clamp protocols including a calcium spike protocol and a mock back-propagating action potential (mBPAP protocol. These experiments enable us to suggest the possible contribution of the five Ca(2+ channel sub-types to Ca(2+ current flow during activation under physiological conditions.

  19. 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

  20. 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.

  1. 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.

  2. Maximum voltage gradient technique for optimization of ablation for typical atrial flutter with zero-fluoroscopy approach.

    Science.gov (United States)

    Deutsch, Karol; Śledź, Janusz; Mazij, Mariusz; Ludwik, Bartosz; Labus, Michał; Karbarz, Dariusz; Pasicka, Bernadetta; Chrabąszcz, Michał; Śledź, Arkadiusz; Klank-Szafran, Monika; Vitali-Sendoz, Laura; Kameczura, Tomasz; Śpikowski, Jerzy; Stec, Piotr; Ujda, Marek; Stec, Sebastian

    2017-06-01

    Radiofrequency catheter ablation (RFCA) is an established effective method for the treatment of typical cavo-tricuspid isthmus (CTI)-dependent atrial flutter (AFL). The introduction of 3-dimensional electro-anatomic systems enables RFCA without fluoroscopy (No-X-Ray [NXR]). The aim of this study was to evaluate the feasibility and effectiveness of CTI RFCA during implementation of the NXR approach and the maximum voltage-guided (MVG) technique for ablation of AFL.Data were obtained from prospective standardized multicenter ablation registry. Consecutive patients with the first RFCA for CTI-dependent AFL were recruited. Two navigation approaches (NXR and fluoroscopy based as low as reasonable achievable [ALARA]) and 2 mapping and ablation techniques (MVG and pull-back technique [PBT]) were assessed. NXR + MVG (n  =  164; age: 63.7 ± 9.5; 30% women), NXR + PBT (n  =  55; age: 63.9 ± 10.7; 39% women); ALARA + MVG (n  =  36; age: 64.2 ± 9.6; 39% women); and ALARA + PBT (n  =  205; age: 64.7 ± 9.1; 30% women) were compared, respectively. All groups were simplified with a 2-catheter femoral approach using 8-mm gold tip catheters (Osypka AG, Germany or Biotronik, Germany) with 15 min of observation. The MVG technique was performed using step-by-step application by mapping the largest atrial signals within the CTI.Bidirectional block in CTI was achieved in 99% of all patients (P  =  NS, between groups). In NXR + MVG and NXR + PBT groups, the procedure time decreased (45.4 ± 17.6 and 47.2 ± 15.7 min vs. 52.6 ± 23.7 and 59.8 ± 24.0 min, P < .01) as compared to ALARA + MVG and ALARA + PBT subgroups. In NXR + MVG and NXR + PBT groups, 91% and 98% of the procedures were performed with complete elimination of fluoroscopy. The NXR approach was associated with a significant reduction in fluoroscopy exposure (from 0.2 ± 1.1 [NXR + PBT] and 0.3 ± 1.6 [NXR + MVG] to 7.7 ± 6.0 min [ALARA + MVG] and 9

  3. Modelling and Simulation of Three Level VSI-Neutral Point Balancing -Fed AC Drive using Intelligence Techniques

    Directory of Open Access Journals (Sweden)

    K.Mohan Krishna

    2015-12-01

    Full Text Available Multilevel inverter topology has developed recently as a very important alternative in the area of high power medium voltage energy control. In multilevel inverter, thethree basic types of topologies used are diode clamped inverter (neutral point clamped, capacitorclamped (flying capacitor and cascaded multi cell with separate dc sources. Multilevel inverters are used in medium voltage and high power applications with less harmonic contents. This paper proposes a software implementation of neutral point clamped (NPC three level voltage source inverter using space vector pulse width modulation (SVPWM techniques. The inverter feeds an electrical system which is controlled by field oriented control (FOC.The improvement of the control technique is achieved using intelligence techniques. The operation of the electrical system is verified in steady state and transient state responses. This software implementation is performed by using matlab/Simulink software. This paper gives comparison between SVPWM three phase three level with neutral point clamped and without neutral point clamped. Finally, the comparative study of different techniques was implemented.

  4. 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.

  5. 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...

  6. Voltage sags and transient detection and classification using half/one-cycle windowing techniques based on continuous s-transform with neural network

    Science.gov (United States)

    Daud, Kamarulazhar; Abidin, Ahmad Farid; Ismail, Ahmad Puad

    2017-08-01

    This paper was conducted to detect and classify the different power quality disturbance (PQD) using Half and One-Cycle Windowing Technique (WT) based on Continuous S-Transform (CST) and Neural Network (NN). The system using 14 bus bars based on IEEE standard had been designing using MATLAB©/Simulink to provide PQD data. The datum of PQD is analyzed by using WT based on CST to extract features and it characteristics. Besides, the study focused an important issue concerning the identification of PQD selection and detection, the feature and characteristics of two types of signals such as voltage sag and transient signal are obtained. After the feature extraction, the classified process had been done using NN to show the percentage of classification PQD either voltage sags or transients. The analysis show which selection of cycle for windowing technique can provide the smooth detection of PQD and the suitable characteristic to provide the highest percentage of classification of PQD.

  7. 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...

  8. Characterization of Highly Efficient CdTe Thin Film Solar Cells by the Capacitance-Voltage Profiling Technique

    Science.gov (United States)

    Okamoto, Tamotsu; Yamada, Akira; Konagai, Makoto

    2000-05-01

    The electrical properties of highly efficient CdTe thin film solar cells prepared by close-spaced sublimation (CSS) were investigated by capacitance-voltage (C-V) measurement. According to the dependence of the cell performance on the substrate temperature in the CSS process, the open-circuit voltage (Voc) increased with increasing the substrate temperature below 630°C@. The carrier concentration profiles revealed that the net acceptor concentration exponentially increased from the CdS/CdTe interface to the rear and that the acceptor concentration increased with increasing substrate temperature. This result suggests that Voc is improved as a result of the increase in the acceptor concentration.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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...

  14. Voltage stability evaluation facing small disturbances by means of the modal analysis technique; Evaluacion de la estabilidad de voltaje ante disturbios pequenos mediante la tecnica de analisis modal

    Energy Technology Data Exchange (ETDEWEB)

    Leon Rodriguez, Daniel

    2000-12-15

    The economic development of the countries has taken implicit a growing industrialization the one which, joined to those every time bigger resident's necessities, it has caused a constant and progressive increment in the electric power demand. However, in the last years the growth of the electric network of these systems has been more and more limited for diverse such factors as the ecology and the economy, as well as for the social and political costs that implies each new construction in the system. With the presence of these restrictions the electric systems in many cases, have been forced to satisfy the increments in the demand making a more exhaustive use of the infrastructure that they have available and the incorporation of only a few new system elements or constructions. These aspects have caused such systems to operate with more limited security margins and that their stability has to be analyzed in a reliable and precise way. Taking into account the previously mentioned aspects, as the electric systems have had the necessity of operating under forced conditions to satisfy the load demand, voltage stability problems have been presented with more frequency causing serious disturbances and in some cases, total blackouts. With these problems, the voltage stability analysis has taken bigger importance in the studies that the electric utilities carry out. This issue has caused that bigger resources are dedicated for the investigation of this phenomenon with the purpose of understanding and developing tools that allow studying it in a more complete and more truthful way. Modal analysis is one of the most recent and popular steady techniques the one that, from its appearance has had a great peak due to the valuable and quick information that provides, besides its implementation easiness and the little effort computational that it requires. In this work is carried out the voltage stability evaluation of a real electric system applying in a combined way the

  15. IVC CLAMP: infrahepatic inferior vena cava clamping during hepatectomy - a randomised controlled trial in an interdisciplinary setting

    Directory of Open Access Journals (Sweden)

    Reissfelder Christoph

    2009-10-01

    Full Text Available Abstract Background Intraoperative haemorrhage is a known predictor for perioperative outcome of patients undergoing hepatic resection. While anaesthesiological lowering of central venous pressure (CVP by fluid restriction is known to reduce bleeding during transection of the hepatic parenchyma its potential side effects remain poorly investigated. In theory it may have negative effects on kidney function and tissue perfusion and bears the risk to result in severe haemodynamic instability in case of profound intraoperative blood loss. The present randomised controlled trial evaluates efficacy and safety of infrahepatic inferior vena cava (IVC clamping as an alternative surgical technique to reduce CVP during hepatic resection. Methods/Design The proposed IVC CLAMP trial is a single-centre randomised controlled trial with a two-group parallel design. Patients and outcome-assessors are blinded for the treatment intervention. Patients undergoing elective hepatic resection due to any reason are enrolled in IVC CLAMP. All patients admitted to the Department of General-, Visceral-, and Transplant Surgery, University of Heidelberg for elective hepatic resection are consecutively screened for eligibility and written informed consent is obtained on the day before surgery. The primary objective of this trial is to assess and compare the amount of blood loss during hepatic resection in patients receiving surgical CVP reduction by clamping of the IVC as compared to anaesthesiological CVP without infrahepatic IVC clamping reduction. In addition to blood loss a set of general as well as surgical variables are analysed. Discussion This is a randomised controlled patient and observer blinded two-group parallel trial designed to assess efficacy and safety of infrahepatic IVC clamping during elective hepatectomy. Trial registration ClinicalTrials NCT00732979

  16. 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...

  17. 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...

  18. 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

  19. 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

  20. A Survey of Non-conventional Techniques for Low-voltage Low-power Analog Circuit Design

    National Research Council Canada - National Science Library

    F. Khateb; S. Bay Abo Dabbous; S. Vlassis

    2013-01-01

    ...). Therefore, this paper presents the operation principle, the advantages and disadvantages of each of these techniques, enabling circuit designers to choose the proper design technique based on application...

  1. Influence of bias voltage on the optical and structural properties of nc-Si:H films grown by layer-by-layer (LBL) deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Goh Boon, E-mail: boontong77@yahoo.co [Solid State Research Laboratory, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Gani, Siti Meriam Ab.; Muhamad, Muhamad Rasat; Rahman, Saadah Abdul [Solid State Research Laboratory, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2009-07-01

    The effects of applying a positive bias of 25 to 100 V on the optical, structural and photoluminescence (PL) properties of hydrogenated nanocrystalline silicon (nc-Si:H) films produced by layer-by-layer (LBL) deposition technique has been studied. Optical characterization of the films has been obtained from UV-VIS-NIR spectroscopy measurements. Structural characterization has been performed using X-ray diffraction, micro-Raman spectroscopy and field emission scanning electron microscope (FESEM). PL spectroscopy technique has been used to investigate the PL properties of the films. In general, the films formed shows a mixed phase of silicon (Si) nanocrystallites embedded within an amorphous phase of the Si matrix. The crystalline volume fraction and grain size of the Si nanocrystallites have been shown to be strongly dependent on the applied bias voltage. High applied bias voltage enhances the growth rate of the films but reduces the refractive index and the optical energy gap of the films. Higher crystalline volume fraction of the films prepared at low bias voltages exhibits room temperature PL at around 1.8 eV (700 nm).

  2. Microstructure Investigation of 13Cr-2Mo ODS Steel Components Obtained by High Voltage Electric Discharge Compaction Technique

    Directory of Open Access Journals (Sweden)

    Igor Bogachev

    2015-11-01

    Full Text Available Refractory oxide dispersion strengthened 13Cr-2Mo steel powder was successfully consolidated to near theoretical density using high voltage electric discharge compaction. Cylindrical samples with relative density from 90% to 97% and dimensions of 10 mm in diameter and 10–15 mm in height were obtained. Consolidation conditions such as pressure and voltage were varied in some ranges to determine the optimal compaction regime. Three different concentrations of yttria were used to identify its effect on the properties of the samples. It is shown that the utilized ultra-rapid consolidation process in combination with high transmitted energy allows obtaining high density compacts, retaining the initial structure with minimal grain growth. The experimental results indicate some heterogeneity of the structure which may occur in the external layers of the tested samples due to various thermal and electromagnetic in-processing effects. The choice of the optimal parameters of the consolidation enables obtaining samples of acceptable quality.

  3. 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

  4. 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...

  5. 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.

  6. 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.

  7. Comparison of Modulation Techniques for Multilevel Inverter fed Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    V. NAGA BHASKAR REDDY

    2010-10-01

    Full Text Available Multilevel inversion is a power conversion strategy in which the output voltage is obtained in steps thus bringing the output closer to a sine wave and reduces the Total Harmonic Distortion. Multilevel inverter structures have been developed to overcome shortcomings in solid-state switching device ratings so that they can be applied to higher voltage systems. In recent years, the multilevel inverters have drawn tremendous interest in the area of high-power medium-voltage energy control. Three different topologies have been proposed for multilevel inverters like Diode-Clamped Inverter, Capacitor Clamped Inverter and Cascaded Multi cell Inverter. In addition, several modulation and control strategies have been developed or adopted for multilevel inverters including the following multilevel Sinusoidal Pulse Width Modulation (SPWM, and Space Vector Modulation. In this paper, simulation of various modulating techniques i.e., Pulse Width Modulate techniques such as Sinusoidal PWM, Trapezoidal PWM, Stepped PWM, Stair case PWM, third harmonicinjected PWM, Modified SVPWM are applied for both Diode Clamped Three-Level Inverter and Diode Clamped Five-Level Inverter, and Space Vector PWM technique are analyzed for DC3LI. The best modulationtechnique are extended to Permanent Magnet Synchronous Motor.

  8. 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

  9. Application of voltage oriented control technique in a fully renewable, wind powered, autonomous system with storage capabilities

    Science.gov (United States)

    Kondylis, Georgios P.; Vokas, Georgios A.; Anastasiadis, Anestis G.; Konstantinopoulos, Stavros A.

    2017-02-01

    The main purpose of this paper is to examine the technological feasibility of a small autonomous network, with electricity storage capability, which is completely electrified by wind energy. The excess energy produced, with respect to the load requirements, is sent to the batteries for storage. When the energy produced by the wind generator is not sufficient, load's energy requirement is covered by the battery system, ensuring, however, that voltage, frequency and other system characteristics are within the proper boundaries. For the purpose of this study, a Voltage Oriented Control system has been developed in order to monitor the autonomous operation and perform the energy management of the network. This system manages the power flows between the load and the storage system by properly controlling the Pulse Width Modulation pulses in the converter, thus ensuring power flows are adequate and frequency remains under control. The experimental results clearly indicate that a stand-alone wind energy system based on battery energy storage system is feasible and reliable. This paves the way for fully renewable and zero emission energy schemes.

  10. Technological Aspects: High Voltage

    CERN Document Server

    Faircloth, D C

    2013-01-01

    This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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. 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

  17. 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.

  18. Evaluation results on the effectiveness of the corrosion protection system for underground pipelines, using the DC-voltage gradient technique

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Antonio Carlos [Petroquimica Uniao S.A., Santo Andre, SP (Brazil)

    2003-07-01

    A pipeline of diameter 6'' with 17.694 km of extension was evaluated how much to the integrity of its external covering and the effectiveness of the system of cathodic protection, using the method DC-Voltage Gradient. The Cathodic Protection in this pipeline is made by seven rectifiers. The gotten data indicate that the potential pipe-ground registered in some check points to the long one of the pipeline is extremely negative, what has led to a super protection of the pipeline for the CP. This if explains for the great proximity between the anodes and the pipeline. For km had been identified 917 failures with a mean density of 50,1 per Km. Beyond the analysis of the data, this work includes conclusions and recommendations detailed for the repairs of the covering of the pipeline and for improvement of the effectiveness of the CP. One sends regards to a combination of repairs in the covering and reevaluation of the CP, in way to improve the protection level and to assure the reduction of the risk of external corrosion. (author)

  19. Voltage Controlled Dynamic Demand Response

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    . An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

  20. Effects of acidic pH on voltage-gated ion channels in rat trigeminal mesencephalic nucleus neurons.

    Science.gov (United States)

    Han, Jin-Eon; Cho, Jin-Hwa; Choi, In-Sun; Kim, Do-Yeon; Jang, Il-Sung

    2017-03-01

    The effects of acidic pH on several voltage-dependent ion channels, such as voltage-dependent K(+) and Ca(2+) channels, and hyperpolarization-gated and cyclic nucleotide-activated cation (HCN) channels, were examined using a whole-cell patch clamp technique on mechanically isolated rat mesencephalic trigeminal nucleus neurons. The application of a pH 6.5 solution had no effect on the peak amplitude of voltage-dependent K(+) currents. A pH 6.0 solution slightly, but significantly inhibited the peak amplitude of voltage-dependent K(+) currents. The pH 6.0 also shifted both the current-voltage and conductance-voltage relationships to the depolarization range. The application of a pH 6.5 solution scarcely affected the peak amplitude of membrane currents mediated by HCN channels, which were profoundly inhibited by the general HCN channel blocker Cs(+) (1 mM). However, the pH 6.0 solution slightly, but significantly inhibited the peak amplitude of HCN-mediated currents. Although the pH 6.0 solution showed complex modulation of the current-voltage and conductance-voltage relationships, the midpoint voltages for the activation of HCN channels were not changed by acidic pH. On the other hand, voltage-dependent Ca(2+) channels were significantly inhibited by an acidic pH. The application of an acidic pH solution significantly shifted the current-voltage and conductance-voltage relationships to the depolarization range. The modulation of several voltage-dependent ion channels by an acidic pH might affect the excitability of mesencephalic trigeminal nucleus neurons, and thus physiological functions mediated by the mesencephalic trigeminal nucleus could be affected in acidic pH conditions.

  1. 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.

  2. DC-Link Capacitor Voltage Regulation for Three-Phase Three-Level Inverter-Based Shunt Active Power Filter with Inverted Error Deviation Control

    Directory of Open Access Journals (Sweden)

    Yap Hoon

    2016-07-01

    Full Text Available A new control technique known as inverted error deviation (IED control is incorporated into the main DC-link capacitor voltage regulation algorithm of a three-level neutral-point diode clamped (NPC inverter-based shunt active power filter (SAPF to enhance its performance in overall DC-link voltage regulation so as to improve its harmonics mitigation performances. In the SAPF controller, DC-link capacitor voltage regulation algorithms with either the proportional-integral (PI or fuzzy logic control (FLC technique have played a significant role in maintaining a constant DC-link voltage across the DC-link capacitors. However, both techniques are mostly operated based on a direct voltage error manipulation approach which is insufficient to address the severe DC-link voltage deviation that occurs during dynamic-state conditions. As a result, the conventional algorithms perform poorly with large overshoot, undershoot, and slow response time. Therefore, the IED control technique is proposed to precisely address the DC-link voltage deviation. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and experimental implementation utilizing a TMS320F28335 Digital Signal Processor (DSP are performed. Moreover, conventional algorithms with PI and FLC techniques are tested too for comparison purposes. Both simulation and experimental results are presented, confirming the improvement achieved by the proposed algorithm in terms of accuracy and dynamic response in comparison to the conventional algorithms.

  3. 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.

  4. DC Bus Control of Back-to-Back Connected Two-Level PWM Rectifier-Five-Level NPC Voltage Source Inverter to Torque Ripple Reduction in Induction Motor

    Directory of Open Access Journals (Sweden)

    Abdelkrim Thameur

    2015-01-01

    Full Text Available This paper proposes a regulation method of back-to-back connected two-level PWM rectifier-five-level Voltage Source Inverter (VSI in order to reduce the torque ripple in induction motor. First part is dedicated to the presentation of the feedback control of two-level PWM rectifier. In the second part, five-level Neutral Point Clamped (NPC voltage source inverter balancing DC bus algorithm is presented. A theoretical analysis with a complete simulation of the system is presented to prove the excellent performance of the proposed technique.

  5. Low concentration contrast medium for dual-source computed tomography coronary angiography by a combination of iterative reconstruction and low-tube-voltage technique: Feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Minwen, E-mail: zhengmw2007@163.com; Liu, Ying, E-mail: yingyinglyly@126.com; Wei, Mengqi, E-mail: weimengqi2008@163.com; Wu, Yongjie, E-mail: wu18291988526@163.com; Zhao, Hongliang, E-mail: zhaohl1980@163.com; Li, Jian, E-mail: xjyylj@yeah.net

    2014-02-15

    Objectives: To assess the impact of low-concentration contrast medium on vascular enhancement, image quality and radiation dose of coronary CT angiography (cCTA) by using a combination of iterative reconstruction (IR) and low-tube-voltage technique. Materials and methods: One hundred patients were prospectively randomized to two types of contrast medium and underwent prospective electrocardiogram-triggering cCTA (Definition Flash, Siemens Healthcare; collimation: 128 mm × 0.6 mm; tube current: 300 mA s). Fifty patients received Iopromide 370 were scanned using the conventional tube setting (100 kVp or 120 kVp if BMI ≥ 25 kg/m{sup 2}) and reconstructed with filtered back projection (FBP). Fifty patients received Iodixanol 270 were scanned using the low-tube-voltage (80 kVp or 100 kVp if BMI ≥ 25 kg/m{sup 2}) technique and reconstructed with IR. CT attenuation was measured in coronary artery and other anatomical regions. Noise, image quality and radiation dose were compared. Results: Compared with two Iopromide 370 subgroups, Iomeprol 270 subgroups showed no significant difference in CT attenuation (576.63 ± 95.50 vs. 569.51 ± 118.93 for BMI < 25 kg/m{sup 2}, p = 0.647 and 394.19 ± 68.09 vs. 383.72 ± 63.11 for BMI ≥ 25 kg/m{sup 2}, p = 0.212), noise (in various anatomical regions of interest) and image quality (3.5 vs. 4.0, p = 0.13), but significantly (0.41 ± 0.17 vs. 0.94 ± 0.45 for BMI < 25 kg/m{sup 2}, p < 0.001 and 1.14 ± 0.24 vs. 2.37 ± 0.69 for BMI ≥ 25 kg/m{sup 2}, p < 0.001) lower radiation dose, which reflects dose saving of 56.4% and 51.9%, respectively. Conclusions: Combined IR with low-tube-voltage technique, a low-concentration contrast medium of 270 mg I/ml can still maintain the contrast enhancement without impairing image quality, as well as significantly lower the radiation dose.

  6. 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...

  7. Critical current density and ac harmonic voltage generation in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films by the screening technique

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Lopez, Israel O., E-mail: iperez@mda.cinvestav.m [Applied Physics Department, Cinvestav Unidad Merida, Km 6 Ant., Carretera a Progreso, A.P. 73, C.P. 97310 Merida, Yucatan (Mexico); Gamboa, Fidel; Sosa, Victor [Applied Physics Department, Cinvestav Unidad Merida, Km 6 Ant., Carretera a Progreso, A.P. 73, C.P. 97310 Merida, Yucatan (Mexico)

    2010-12-15

    The temperature and field dependence of harmonics in voltage V{sub n}=V{sub n}{sup '}-iV{sub n}{sup ''} using the screening technique have been measured for YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} superconducting thin films. Using the Sun model we obtained the curves for the temperature-dependent critical current density J{sub c}(T). In addition, we applied the criterion proposed by Acosta et al. to compute J{sub c}(T). Also, we made used of the empirical law J{sub c{proportional_to}}(1-T/T{sub c}){sup n} as an input in our calculations to reproduce experimental harmonic generation up to the fifth harmonic. We found that most models fit well the fundamental voltage but higher harmonics are poorly reproduced. Such behavior suggests the idea that higher harmonics contain information concerning complex processes like flux creep or thermally assisted flux flow.

  8. Developement of new measuring techniques. A measuring system for testing GIS disconnectors in a high voltage laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Carubelli, C.; Cremonesi, F.; Santagostino, G.

    1988-10-01

    Within the framework of the cooperation between CESI (Italy) and the CPRI (Central Power Research Institute), the problem of a fast and accurate measurements systems for gas-insulated substations (GIS) disconnector testing was analyzed. The particular complexity of the transients to be studied has led to the development of a composite system in which the high frequency components are dealt with by analog techniques and medium frequency components are handled with digital techniques. Sophisticate software was developed to combine the measurement results. Further improvements are expected with the development of a fiber-optics link with an extended bandwidth and the adoption of a digital oscilloscope in order to simplify the overall management of the tests.

  9. 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

  10. 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

  11. Impact of metal overhang and guard ring techniques on breakdown voltage of Si strip sensors - 2003 IEEE nuclear science symposium, medical imaging conference, and workshop of room-temperature semiconductor detectors

    CERN Document Server

    Ranjan, K; Namrata, S; Chatterji, S; Srivastava-Ajay, K; Kumar, A; Jha, Manoj Kumar; Shivpuri, R K

    2004-01-01

    The importance of Si sensors in high-energy physics (HEP) experiments can hardly be overemphasized. However, the high luminosity and the high radiation level in the future HEP experiments, like Large Hadron Collider (LHC), has posed a serious challenge to the fabrication of Si detectors. For the safe operation over the full LHC lifetime, detectors are required to sustain very high voltage operation, well exceeding the bias voltage needed to full deplete the heavily irradiated Si sensors. Thus, the main effort in the development of Si sensors is concentrated on a design that avoids p-n junction breakdown at operational biases. Among various proposed techniques, Field-limiting Ring (FLR) (or guard ring) and Metal-Overhang (MO) are technologically simple and are suitable for vertical devices. Since high-voltage planar Si junctions are of great importance in the HEP experiments, it is very interesting to compare these two aforementioned techniques for achieving the maximum breakdown voltage under optimal conditio...

  12. 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.

  13. 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

  14. New Technique for Voltage Tracking Control of a Boost Converter Based on the PSO Algorithm and LTspice

    DEFF Research Database (Denmark)

    Farhang, Peyman; Drimus, Alin; Mátéfi-Tempfli, Stefan

    2015-01-01

    the optimal solutions is run in MATLAB while it is interfaced with LTspice for simulation of the circuit using actual component models obtained from manufacturers. The PSO is utilized to solve the optimization problem in order to find the optimal parameters of MPID and PID controllers. The performances......In this paper, a new technique is proposed to design a Modified PID (MPID) controller for a Boost converter. An interface between LTspice and MATLAB is carried out to implement the Particle Swarm Optimization (PSO) algorithm. The PSO algorithm which has the appropriate capability to find out...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    the proposed modulation strategy, the four-leg NPC inverter can be decoupled into three three-level Buck converters in each defined operating section. This makes the controller design much simpler compared to the conventional four-leg NPC inverter controllers. Also, this technique can be implemented......In this paper, a modulation strategy based on the circuit-level decoupling concept is proposed and investigated for the three-level four-leg neutral-point-clamped (NPC) inverter,with the aim of delivering power to all sorts of loads, linear/nonlinear and balanced/unbalanced. By applying...... with a simple logic and can be processed very quickly. Moreover, the switching loss is reduced substantially and the dc-link capacitors’ voltages balance is also achieved without any feedback control. The proposed modulation technique is verified by the experiment....

  16. 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.

  17. High voltage engineering fundamentals

    CERN Document Server

    Kuffel, E; Hammond, P

    1984-01-01

    Provides a comprehensive treatment of high voltage engineering fundamentals at the introductory and intermediate levels. It covers: techniques used for generation and measurement of high direct, alternating and surge voltages for general application in industrial testing and selected special examples found in basic research; analytical and numerical calculation of electrostatic fields in simple practical insulation system; basic ionisation and decay processes in gases and breakdown mechanisms of gaseous, liquid and solid dielectrics; partial discharges and modern discharge detectors; and over

  18. 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.

  19. 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.

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

    KAUST Repository

    Jaber, Nizar R.

    2017-04-07

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

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

    KAUST Repository

    Bataineh, Ahmad M.

    2014-10-18

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

  2. 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...

  3. 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...

  4. 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...

  5. 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.

  6. 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.

  7. A 5-bit time to digital converter using time to voltage conversion and integrating techniques for agricultural products analysis by Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Mahdi Rezvanyvardom

    2014-12-01

    Full Text Available Time to digital converter (TDC is a key block for time-gated single photon avalanche diode (SPAD arrays for Raman spectroscopy that applicable in the agricultural products and food analysis. In this paper a new dual slope time to digital converter that employs the time to voltage conversion and integrating techniques for digitizing the time interval input signals is presented. The reference clock frequency of the TDC is 100 MHz and the input range is theoretically unlimited. The proposed converter features high accuracy, very small average error and high linear range. Also this converter has some advantages such as low circuit complexity, low power consumption and low sensitive to the temperature, power supply and process changes (PVT compared with the time to digital converters that used preceding conversion techniques. The proposed converter uses an indirect time to digital conversion method. Therefore, our converter has the appropriate linearity without extra elements. In order to evaluate the proposed idea, an integrating time to digital converter is designed in 0.18 μm CMOS technology and was simulated by Hspice. Comparison of the theoretical and simulation results confirms the proposed TDC operation; therefore, the proposed converter is very convenient for applications which have average speed and low variations in the signal amplitude such as biomedical signals.

  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. A novel monolithic piezoelectric actuated flexure-mechanism based wire clamp for microelectronic device packaging

    Science.gov (United States)

    Liang, Cunman; Wang, Fujun; Tian, Yanling; Zhao, Xingyu; Zhang, Hongjie; Cui, Liangyu; Zhang, Dawei; Ferreira, Placid

    2015-04-01

    A novel monolithic piezoelectric actuated wire clamp is presented in this paper to achieve fast, accurate, and robust microelectronic device packaging. The wire clamp has compact, flexure-based mechanical structure and light weight. To obtain large and robust jaw displacements and ensure parallel jaw grasping, a two-stage amplification composed of a homothetic bridge type mechanism and a parallelogram leverage mechanism was designed. Pseudo-rigid-body model and Lagrange approaches were employed to conduct the kinematic, static, and dynamic modeling of the wire clamp and optimization design was carried out. The displacement amplification ratio, maximum allowable stress, and natural frequency were calculated. Finite element analysis (FEA) was conducted to evaluate the characteristics of the wire clamp and wire electro discharge machining technique was utilized to fabricate the monolithic structure. Experimental tests were carried out to investigate the performance and the experimental results match well with the theoretical calculation and FEA. The amplification ratio of the clamp is 20.96 and the working mode frequency is 895 Hz. Step response test shows that the wire clamp has fast response and high accuracy and the motion resolution is 0.2 μm. High speed precision grasping operations of gold and copper wires were realized using the wire clamper.

  10. 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.

  11. 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.

  12. The long-term results of Magerl technique combined with single laminar clamp internal fixation in management of atlantoaxial dislocation%Magerl技术联合单椎板夹固定治疗寰枢椎脱位的远期疗效

    Institute of Scientific and Technical Information of China (English)

    魏富鑫; 李浩淼; 刘少喻; 王乐; 崔尚斌; 钟锐; 陈柏龄; 龙厚清; 李佛保

    2015-01-01

    Objective To evaluate the long-term outcomes of Magerl technique combined with single laminar clamp internal fixation in management of atlantoaxial dislocation.Methods A retrospective study included 11 patients with atlantoaxial dislocation,who were treated with Magerl technique combined with single laminar clamp internal fixation and bone fusion after preoperative traction and reduction.Postoperative complications and efficacy were observed subsequently.The clinical and radiological outcomes were evaluated according to the Symonand Lavender clinical standard,the spinal function score of Japanese Orthopaedic Association (JOA),the imaging index space available for the cord (SAC),and the atlas-dens interval (ADI).The status of bony fusion was also evaluated according to radiological investigation.Results The mean operating time was 101 ±66 mins (range,72-160 mins),and the mean bleeding during operation was 180±395 ml (range,70-550 ml).All the patients achieved bone fusion.There was no neurological damage,wound infection or other serious complications.Only one patient showed delayed healing of incision,who was treated successfully with debridement and re-suturing.All the patients were followed up successfully with an average of 67.8±65.3 months (range,48-128 months),and there were no breakage of screws or laminar clamps.According to the Symonand Lavender clinical standard,the clinical recovery rate was 90.9%.According to the JOA score,there was a significant difference between the preoperative JOA score and the final follow-up,which increased by 7.0±3.3 points with an average recovery rate of 86.4%.The SAC of C1,2 segment increased by 7.29 mm at one month postoperatively,which showed a significant difference compared with preoperative SAC.The SAC at the final follow-up was 16.91±0.51 mm,which showed no significant difference compared with that at one month postoperatively.The ADI at one month postoperatively decreased by 4.51 ± 1.46 mm,which showed a

  13. 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.

  14. 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+.

  15. 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.

  16. 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.

  17. 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.

  18. 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...

  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. A new technique to study transient conductivity under pulsed monochromatic light in Cr-doped GaAs using acoustoelectric voltage measurement

    Science.gov (United States)

    Tabib-Azar, Massood

    1991-01-01

    The transient conductivity of high-resistivity Bridgman-grown Cr-doped GaAs under pulsed monochromatic light is monitored using transverse acoustoelectric voltage (TAV) at 83 K. Keeping the photon flux constant, the height and transient time constant at the TAV are used to calculate the energy dependence of the trap density and its cross section, respectively. Two prominent trap profiles with peak trap densities of approximately 10 to the 17th/cu cm eV near the valence and the conduction bands are detected. These traps have very small capture cross sections in the range of 10 to the -23 to 10 to the -21st cm sq. A phenomenon similar to the persistent photoconductivity with transient time constants in excess of a few seconds in high-resistivity GaAs at T = 83 K is also detected using this technique. These long relaxation times are readily explained by the spatial separation of the photo-excited electron-hole pairs and the small capture cross section and large density of trap distribution near the conduction band.

  2. Behaviour of total surface charge in SiO{sub 2}-Si system under short-pulsed ultraviolet irradiation cycles characterised by surface photo voltage technique

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Ban-Hong [Material Characterization Department, Shin Etsu Handotai (M) Sdn. Bhd., Ulu Klang, Selangor (Malaysia); Lee, Wah-Pheng [Faculty of Engineering, Multimedia University, Persiaran Multimedia, Cyberjaya, 63100 Selangor (Malaysia); Yow, Ho-Kwang, E-mail: hkyow@mmu.edu.my [Faculty of Engineering, Multimedia University, Persiaran Multimedia, Cyberjaya, 63100 Selangor (Malaysia); Tou, Teck-Yong [Faculty of Engineering, Multimedia University, Persiaran Multimedia, Cyberjaya, 63100 Selangor (Malaysia)

    2009-04-15

    Effects of time-accumulated ultraviolet (UV) irradiation and surface treatment on thermally oxidized p-type silicon wafers were investigated by using the surface photo voltage (SPV) technique via the direct measurement of the total surface charge, Q{sub SC}. The rise and fall times of Q{sub sc} curves, as a function of accumulated UV irradiation, depended on the thermal oxide thickness. A simple model was proposed to explain the time-varying characteristics of Q{sub sc} based on the UV-induced bond breaking of SiOH and SiH, and photoemission of bulk electrons to wafer surface where O{sub 2}{sup -} charges were formed. While these mechanisms resulted in charge variations and hence in Q{sub sc}, these could be removed by rinsing the silicon wafers in de-ionized water followed by spin-dry or blow-dry by an ionizer fan. Empirical parameters were used in the model simulations and curve-fitting of Q{sub SC}. The simulated results suggested that initial changes in the characteristic behaviour of Q{sub sc} were mainly due to the net changes in the positive and negative charges, but subsequently were dominated by the accumulation of O{sub 2}{sup -} during the UV irradiation.

  3. 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.

  4. 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.

  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. 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...

  7. 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.

  8. Incision Below The Clamp sebagai Modifikasi Teknik Insisi pada Frenektomi untuk Minimalisasi Perdarahan

    Directory of Open Access Journals (Sweden)

    S. Suryono

    2016-10-01

    Full Text Available Latar Belakang. Perlekatan frenulum tinggi berdampak merugikan bagi jaringan periodontal maupun fungsi estetik. Perlekatan tinggi yang terjadi pada labialis superior, menimbulkan gingivitis dan sentral diastema yang menjadikan indikasi untuk dilakukan frenektomi. Frenektomi dengan teknik melakukan insisi di atas dan di bawah clamp berakibat lebarnya luka karena tarikan otot bibir, yang berdampak terjadi banyak perdarahan. Tujuan. Melakukan evaluasi terhadap modifikasi teknik insisi yang diharapkan dapat mengurangi perdarahan. Kasus dan Penanganan. Laporan kasus ini memaparkan penanganan kasus pada perlekatan frenulum tinggi yang diikuti adanya sentral diastema. Pasien dengan diagnosa frenulum tinggi dan indikasi frenektomi dilakukan tindakan preoperasi. Tindakan operasi dilakukan dengan menggunakan pisau bedah, modifikasi insisi (Insision below the Clamp dilakukan dengan cara menempatkan clamp frenulum pada posisi yang berdekatan dan sejajar dengan bibir, tindakan insisi dilakukan di bawah clamp, disusul dengan penjahitan pada area mucolabial fold. Selama operasi dilakukan terlihat luka tidak melebar, tidak banyak darah yang keluar, pasien dan dokter merasa nyaman. Kesimpulan. Insision below the Clamp merupakan modifikasi teknik insisi pada frenektomi yang bisa dilakukan oleh para praktisi untuk meminimalisir perdarahan yang terjadi selama proses pengambilan frenulum dengan menggunakan pisau bedah.   Background. Attachment of high frenulum has negative impact on periodontal tissues as well as an aesthetic function. High attachment of frenulum that occurs in labialis superior, causing gingivitis and central diastema that are indications to do Frenectomy. Conventional techniques of Frenectomy performed with insisions above and below the clamp resulted in wide injury due to muscle contraction, which affects a lot of bleeding. Objective. To evaluate modification insision technique which hopefully can minimize the bleeding. Case and Treatment. This

  9. 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

  10. 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

  11. 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.

  12. Unconventional Specimen Preparation Techniques Using High Resolution Low Voltage Field Emission Scanning Electron Microscopy to Study Cell Motility, Host Cell Invasion, and Internal Cell Structures in Toxoplasma gondii

    Science.gov (United States)

    Schatten, Heide; Ris, Hans

    2002-04-01

    Apicomplexan parasites employ complex and unconventional mechanisms for cell locomotion, host cell invasion, and cell division that are only poorly understood. While immunofluorescence and conventional transmission electron microscopy have been used to answer questions about the localization of some cytoskeletal proteins and cell organelles, many questions remain unanswered, partly because new methods are needed to study the complex interactions of cytoskeletal proteins and organelles that play a role in cell locomotion, host cell invasion, and cell division. The choice of fixation and preparation methods has proven critical for the analysis of cytoskeletal proteins because of the rapid turnover of actin filaments and the dense spatial organization of the cytoskeleton and its association with the complex membrane system. Here we introduce new methods to study structural aspects of cytoskeletal motility, host cell invasion, and cell division of Toxoplasma gondii, a most suitable laboratory model that is representative of apicomplexan parasites. The novel approach in our experiments is the use of high resolution low voltage field emission scanning electron microscopy (LVFESEM) combined with two new specimen preparation techniques. The first method uses LVFESEM after membrane extraction and stabilization of the cytoskeleton. This method allows viewing of actin filaments which had not been possible with any other method available so far. The second approach of imaging the parasite's ultrastructure and interactions with host cells uses semithick sections (200 nm) that are resin de-embedded (Ris and Malecki, 1993) and imaged with LVFESEM. This method allows analysis of structural detail in the parasite before and after host cell invasion and interactions with the membrane of the parasitophorous vacuole as well as parasite cell division.

  13. Optimización de Tensión en Redes de Distribución utilizando Técnicas de Optimización Evolutiva Power Distribution Network Voltage Optimization using Evolutionary Optimization Techniques

    Directory of Open Access Journals (Sweden)

    Francisco G Montoya

    2006-01-01

    Full Text Available Se ha implementado una técnica que resuelve el problema del desvío de perfil óptimo de tensión en una red eléctrica de distribución. Para una red eléctrica, se puede ajustar la tensión de sus nodos, actuando en los cambiadores de tomas de los transformadores de distribución de dicha red. La idea básica persigue obtener un conjunto de valores para las tomas de los transformadores, que aplicadas en dichas máquinas, consigan aproximar, lo máximo posible, las tensiones de los nudos eléctricos que controlan a la tensión nominal. Para ello se utilizan técnicas matemáticas basadas en algoritmos evolutivos desarrolladas en entorno Matlab®. Se han obtenido perfiles óptimos de tensión, minimizando la desviación cuadrática media de las tensiones.A new technique to solve the problem of deviation of the optimum voltage profile in power distribution networks has been developed. The node voltage can be adjusted, operating the under-load tap changer (ULTC. The main idea is to get a set of values for the ULTC’s tape changer that can approximate the node voltage, that they are controlling, to the nominal node voltage. To solve the problem, evolutionary algorithm techniques implemented in Matlab® have been developed. Optimum voltage profiles are been obtained, minimizing the mean square root of node voltage.

  14. 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.

  15. 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.

  16. Functional reconstitution of the voltage-regulated sodium channel purified from electroplax of Electrophorus electricus

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, R.L.

    1985-01-01

    The voltage-regulated NA channel is responsible for the depolarization of the excitable cell membrane during the normal action potential. This research has focused on the functional properties of the Na channel, purified from detergent extracts of electroplax membranes of the electric eel, and reconstituted into vesicles of defined phospholipid. These properties were assessed by measuring neurotoxin-modulated ion flux into the reconstituted membrane vesicles and by recording the single-channel currents of the purified channel by the patch-clamp method. The binding of tritiated tetrodotoxin (TTX) was employed as a marker for the purification of the channel. Two high-resolution fractionation steps, based on molecular charge and protein size, were used to obtain a preparation that is 80% homogeneous for a large peptide of 270,000 daltons. Radiotracer /sup 22/Na/sup +/ influx into the vesicles was stimulated by veratridine and by batrachotoxin (BTX) at concentrations of 100 ..mu..M and 5 ..mu..M, respectively. The stimulation by BTX was greater than that by veratridine, and can be as much as 16-fold over control influx levels. The stimulated influx is blocked by TTX with a K/sub i/ of 35 nM, and by local anesthetics in the normal pharmacological range. Large multilamellar vesicles prepared with a freeze-thaw step are suitable for single-channel recording techniques. When excised patches of the reconstituted membranes were voltage-clamped in the absence of activating neurotoxins, voltage-dependent single-channel currents were recorded. These displayed properties similar to those from native membranes of nerve and muscle. These results indicate that the protein purified on the basis of TTX binding is a functional Na channel possessing these functional domains: the ion-selective channel, the voltage sensors controlling activation and inactivation, and the sites of action of TTX, alkaloid neurotoxins, and local anesthetics.

  17. 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.

  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. 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....

  20. 电缆绝缘电阻测试仪中高压电源的设计*%Design of High-Voltage Power Supply of Cable Insulation Resistance Tester

    Institute of Scientific and Technical Information of China (English)

    李琳琳; 王二宝; 孙继银; 恒波; 肖明芳

    2013-01-01

      To meet the power requirements of inputting low voltage and outputting high-voltage during cable insulation resistance test, the paper proposes a new type of active clamp voltage multiplying converters by analyzing and improving the technical of analysis active clamp pulse width modulation and voltage double rectifier. It uses main circuit in active clamp technique to achieve magnetic core flux automatic reset and increases core utilization. The clamp capacitor with other components produces resonant achieving opened switch to zero pressure, which reduces the switching loss and voltage stress. Doubling voltage technique is used to reduce transformer step-up requirements and converter bulk. Taking advantage of negative feedback in control loop,input output voltage into PWM chip and control pulse duty cycle can increase power stability and load characteristics. The software simulation result shows that the converter is able to provide a stable high insulation resistance test voltage.%  为满足电缆绝缘电阻测试“低电压输入,高电压输出”的需求,对有源钳位、脉宽调制和倍压整流等技术分析改进,提出一种新型的有源钳位倍压变换器。主回路中利用有源钳位技术实现磁芯磁通自动复位,提高了磁芯利用率,钳位电容与元器件产生谐振实现开关零压开通,减小开关损耗和电压应力;利用倍压技术降低变压器升压要求,减小了变换器体积;在控制回路中利用负反馈将输出电压输入脉宽调制芯片,控制脉冲占空比,提高了电源稳定性和负载特性。用软件仿真结果表明,该变换器能够为绝缘电阻测试提供稳定的高电压。

  1. 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.

  2. 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

  3. 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.

  4. A Digitally Dynamic Power Supply Technique for 16-Channel 12 V-Tolerant Stimulator Realized in a 0.18-μm 1.8-V/3.3-V Low-Voltage CMOS Process.

    Science.gov (United States)

    Luo, Zhicong; Ker, Ming-Dou; Yang, Tzu-Yi; Cheng, Wan-Hsueh

    2017-07-18

    A new digitally dynamic power supply technique for 16-channel 12-V-tolerant stimulator is proposed and realized in a 0.18-μm 1.8-V/3.3-V CMOS process. The proposed stimulator uses four stacked transistors as the pull-down switch and pull-up switch to withstand 4 times the nominal supply voltage (4 × V DD). With the dc input voltage of 3.3 V, the regulated three-stage charge pump, which is capable of providing 11.3-V voltage at 3-mA loading current, achieves dc conversion efficiency of up to 69% with 400-pF integrated capacitance. Power consumption is reduced by implementing the regulated charge pump to provide a dynamic dc output voltage with a 0.5-V step. The proposed digitally dynamic power supply technique, which is implemented by using a p-type metal oxide semiconductor (PMOS) inverter with pull-down current source and digital controller, greatly improves the power efficiency of a system. The silicon area of the stimulator is approximately 3.5 mm2 for a 16-channel implementation. The functionalities of the proposed stimulator have been successfully verified through animal test.

  5. 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.

  6. 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...

  7. 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....

  8. 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.

  9. 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.

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

    Science.gov (United States)

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

    2017-07-01

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

  11. 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.

  12. 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.

  13. Selective serotonin reuptake inhibitor sertraline inhibits voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells

    Indian Academy of Sciences (India)

    HAN SOL KIM; HONGLIANG LI; HYE WON KIM; SUNG EUN SHIN; IL-WHAN CHOI; AMY L FIRTH; HYOWEON BANG; YOUNG MIN BAE; WON SUN PARK

    2016-12-01

    We examined the effects of the selective serotonin reuptake inhibitor (SSRI) sertraline on voltage-dependent K+ (Kv)channels in freshly isolated rabbit coronary arterial smooth muscle cells using the voltage-clamp technique. Sertralinedecreased the Kv channel current in a dose-dependent manner, with an IC50 value of 0.18 μM and a slope value (Hillcoefficient) of 0.61. Although the application of 1 μM sertraline did not affect the steady-state activation curves,sertraline caused a significant, negative shift in the inactivation curves. Pretreatment with another SSRI, paroxetine,had no significant effect on Kv currents and did not alter the inhibitory effects of sertraline on Kv currents. From theseresults, we concluded that sertraline dose-dependently inhibited Kv currents independently of serotonin reuptakeinhibition by shifting inactivation curves to a more negative potential.

  14. Selective serotonin reuptake inhibitor sertraline inhibits voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells.

    Science.gov (United States)

    Kim, Han Sol; Li, Hongliang; Kim, Hye Won; Shin, Sung Eun; Choi, Il-Whan; Firth, Amy L; Bang, Hyoweon; Bae, Young Min; Park, Won Sun

    2016-12-01

    We examined the effects of the selective serotonin reuptake inhibitor (SSRI) sertraline on voltage-dependent K+ (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells using the voltage-clamp technique. Sertraline decreased the Kv channel current in a dose-dependent manner, with an IC50 value of 0.18 mu M and a slope value (Hill coefficient) of 0.61. Although the application of 1 mu M sertraline did not affect the steady-state activation curves, sertraline caused a significant, negative shift in the inactivation curves. Pretreatment with another SSRI, paroxetine, had no significant effect on Kv currents and did not alter the inhibitory effects of sertraline on Kv currents. From these results, we concluded that sertraline dose-dependently inhibited Kv currents independently of serotonin reuptake inhibition by shifting inactivation curves to a more negative potential.

  15. 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.

  16. 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.

  17. 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.

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

    Science.gov (United States)

    Cheng, Lan; Sanguinetti, Michael C

    2009-05-01

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

  19. 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.

  20. 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.

  1. 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.

  2. Development of a Technique for Representing Lightning Arresters in the Surge Simulations based on the FDTD Method and its Application to the Calculation of Lightning-Induced Voltages on a Distribution Line

    Science.gov (United States)

    Tatematsu, Akiyoshi; Noda, Taku

    Recently, the FDTD (Finite Difference Time Domain) method, which directly solves Maxwell's equations, has been applied to lightning surge problems involving electrical wires in three-dimensional arrangements, such as power and telecommunication circuits. Lightning arresters are installed to protect the circuits from abnormal voltages due to lightning, for example. We have already proposed a technique for representing a lightning arrester in the FDTD method. However, this technique simply represents the V-I characteristics of the arrester using just three parameters and requires a method for avoiding the numerical oscillation due to the nonlinear characteristics of the arrester. In this paper, we propose a new technique for representing the V-I characteristics of the arrester in detail using the piecewise linear function defined by several points and for improving the numerical stability without the method for avoiding the numerical oscillation. Using a test circuit, the proposed technique is validated by comparing the results calculated by the FDTD method with those by the EMTP (ElectroMagnetic Transients Program) which is a circuit-theory-based simulation program. Finally, as an example of applying the proposed technique, we calculate lightning-induced voltages on a distribution line with a lightning arrester. The calculated results by the FDTD method agree well with those by a conventional method based on circuit theroy.

  3. 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.

  4. 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.

  5. A Review and Performance Investigation of NPCC Based UPQC by Using Various Artificial Intelligence Techniques

    Directory of Open Access Journals (Sweden)

    Venkata Rami Reddy K

    2017-03-01

    Full Text Available This paper presents a comprehensive review and performance investigation of Neutral Point Clamped Converter (NPCC based Unified Power Quality Conditioner (UPQC by using Artificial Intelligent (AI techniques. A Novel application of various levels of Diode Clamped Multi-Level Inverters [DCMLI] with Anti Phase Opposition and Disposition (APOD Pulse Width Modulation (PWM Scheme to Unified Power Quality Conditioner (UPQC. The Power Quality problem became a burning issues since the starting of high voltage AC transmission system. Hence, in this article it has been discussed to mitigate the PQ issues in high voltage AC systems through a three phase four wire Unified Power Quality Conditioner (UPQC under non-linear loads. The emphasised PQ problems such as voltage and current harmonics along with voltage sags and swells have also been discussed with improved performance. Also, it proposes to control the DCMLI based UPQC through conventional control schemes. Thus application of these control technique makes the system performance in par with the standards and also compared with existing system. The simulation results based on MATLAB/Simulink are discussed in detail to support the concept developed in the paper.

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

    Science.gov (United States)

    French, C R; Sah, P; Buckett, K J; Gage, P W

    1990-06-01

    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 currents could also be recorded directly in dissociated neurons in which other ionic currents were effectively suppressed. It was concluded that the persistent current was carried by sodium ions because it was blocked by TTX, decreased in amplitude when extracellular sodium concentration was reduced, and was not blocked by cadmium. The amplitude of the persistent sodium current varied with clamp potential, being detectable at potentials as negative as -70 mV and reaching a maximum at approximately -40 mV. The maximum amplitude at -40 mV in 21 cells in slices was -0.34 +/- 0.05 nA (mean +/- 1 SEM) and -0.21 +/- 0.05 nA in 10 dissociated neurons. Persistent sodium conductance increased sigmoidally with a potential between -70 and -30 mV and could be fitted with the Boltzmann equation, g = gmax/(1 + exp[(V' - V)/k)]). The average gmax was 7.8 +/- 1.1 nS in the 21 neurons in slices and 4.4 +/- 1.6 nS in the 10 dissociated cells that had lost their processes indicating that the channels responsible are probably most densely aggregated on or close to the soma. The half-maximum conductance occurred close to -50 mV, both in neurons in slices and in dissociated neurons, and the slope factor (k) was 5-9 mV. The persistent sodium current was much more resistant to inactivation by depolarization than the transient current and could be recorded at greater than 50% of its normal amplitude when the transient current was completely inactivated. Because the persistent sodium current activates at

  7. 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.

  8. 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

  9. 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

  10. 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...

  11. 后腹腔镜bulldog夹阻断肾动脉连续缝合行肾部分切除术24例分析%Retroperitoneal laparoscopic partial nephrectomy utilizing bulldog clamp blocking renal artery and continuous suture technique in 24 cases

    Institute of Scientific and Technical Information of China (English)

    王德林; 蒲军; 张尧; 杨军; 吴小候

    2011-01-01

    目的 评价后腹腔镜下bulldog夹阻断肾动脉连续缝合行肾部分切除术的临床疗效及价值.方法 回顾性分析24例后腹腔镜肾部分切除术患者的一般临床资料、手术结果及预后情况.结果 所有患者手术均成功,术中无输血及中转开腹手术,平均手术时间为143.3 min,平均热缺血时间为24 min;术后无继发出血、感染及漏尿,术后病理检查证实8例为肾透明细胞癌,16例为平滑肌脂肪瘤;随访2~36个月无转移、局部复发.结论 后腹腔镜下bulldog夹阻断肾动脉连续缝合行肾部分切除术治疗直径小于4.5 cm肾肿瘤安全、有效.%Objective To evaluate clinical efficacy and value of retroperitoneal laparoscopic partial nephrectomy utilizing bulldog clamp blocking renal artery and continuous suture technique. Methods 24 cases of retroperitoneal laparoscopic partial nephrectomy in patients were retrospectively analyzed, with the clinical data, surgical results, prognosis for their treatment. Results All operations were successful without intraoperative conversion and transfusion,and no post-operative bleeding,inflammation and leakage of urine was found. The average operative time was 143. 3 min,the average warm ischemia time was 24 min. Pathology showed 8 cases of renal cell carcinoma, 16 cases of angiomyolipoma. The follow-up time was 2-36 months without local recurrence and metastasis. Conclusion retroperitoneal laparoscopic partial nephrectomy for diameter less than 4. 5 cm renal tumor is safe and effective.

  12. 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.

  13. 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.

  14. AN ANTHOLOGY OF THE DISTINGUISHED ACHIEVEMENTS IN SCIENCE AND TECHNIQUE. PART 28: PORTRAITS OF LEGENDARY PHYSICISTS OF «HIGH-VOLTAGE BRIGADE» OF UPHTI

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2015-11-01

    Full Text Available Purpose. Description of the basic distinguished scientific achievements of members of «high-voltage brigade» of the Ukrainian Physical-Technical Institute (UPhTI and future Academicians in area of nuclear physics − Valter A.C., Sinelnikov C.D., Leypunskiy A.I. and Latyshev G.D. Methodology. Scientific approaches at treatment and systematization of physical knowledges. Historical method at research of development in Ukraine and Russia of nuclear physics and mastering of intranuclear energy for military and peaceful aims. Results. The basic creative and vital stages, and also prominent scientific results, obtained by the indicated scientists in the area of nuclear physics, physics of high energies and nuclear energy, are resulted in the compressed and systematized way. Some technical descriptions created by these Kharkov physicists of powerful high-voltage electrostatic and linear dynamitrons and protons, and also nuclear reactors fast-neutron are indicated. Originality. Firstly in the area of history of scientific-technological authoritative enough scientist-electro-physicist, which is engaged not alone ten of years by creation of powerful generators of very high voltage and large currents, and also presents a theoretical electrophysics a wide reader a scientifically-historical essay with not popular details about the first in the USSR breaking up the physicists of UPhTI of atomic kernel of lithium by artificially speed-up protons. Firstly the basic distinguished scientific achievements of the considered physicists-nuclear engineers are resulted in the concentrated way. Practical value. Scientific popularization of physical knowledges and achievements of the known compatriots, bringing in a big contribution to development of nuclear physics, physicists of high energies and nuclear energy.

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Research of reduced common-mode voltage technique with nonzero vector pulse width modulation for three-phase inverters%三相逆变器的无零矢量共模电压抑制技术研究

    Institute of Scientific and Technical Information of China (English)

    章勇高; 邝光健; 龙立中

    2013-01-01

    The common-mode suppression techniques with nonzero vector pulse width modulation (NZPWM) for three-phase inverters are studied. They are random state pulse width modulation (RSPWM), active zero state PWM1 (AZSPWM1), active zero state PWM3 (AZSPWM3) and near state PWM (NSPWM). Firstly, the operation areas of modulation factor and reference voltage vector with different modulation strategies are analyzed. The results show that RSPWM has a smaller operation area than other three NZPWM and is suitable for the application with lower modulation ratio. Secondly, the DC voltage utilization rate and output harmonic of different NZPWM are researched and compared with that of traditional space vector modulation (SVM) by using theoretical analysis and simulation. The results show that AZPWM1, AZPWM3 and NSPWM can not only suppress the common mode voltage of three-phase inverters efficiently, but also maintain high DC voltage utilization rate. However, three-phase inverters with NSPWM have the higher output harmonic comparing with the traditional SVM. The research results provide theoretical basis and instruction for the selection of common mode voltage suppression technique with NZPWM for three-phase inverters and its further study.%  研究了三相逆变器的 RSPWM、AZSPWM1、AZSPWM3和 NSPWM 无零矢量共模电压抑制技术。首先,分析了不同调制策略的调制因数和参考电压矢量的工作区间,说明了 RSPWM 的工作区间较小,适用于低调制比工作场合。再次,利用理论分析和仿真方法,研究了无零矢量调制策略的直流电压利用率和输出谐波特性,并与传统 SVM 调制策略比较。结果表明,AZSPWM1、AZSPWM3和 NSPWM 调制策略能够有效地抑制三相逆变器共模电压,同时保持了较高的直流电压利用率。但相对 SVM 调制策略,三相逆变器的输出谐波含量有所增大。研究结果为三相逆变器的无零矢量共模电压抑制技术的选用及进一步研究提供了理论依据和指导。

  1. 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...

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Umbilical Cord Milking Versus Delayed Cord Clamping in Preterm Infants.

    Science.gov (United States)

    Katheria, Anup C; Truong, Giang; Cousins, Larry; Oshiro, Bryan; Finer, Neil N

    2015-07-01

    Delayed cord clamping (DCC) is recommended for premature infants to improve blood volume. Most preterm infants are born by cesarean delivery (CD), and placental transfusion may be less effective than in vaginal delivery (VD). We sought to determine whether infants umbilical cord milking (UCM) have higher measures of systemic blood flow than infants who undergo DCC. This was a 2-center trial. Infants delivered by CD were randomly assigned to undergo UCM or DCC. Infants delivered by VD were also randomly assigned separately. UCM (4 strippings) or DCC (45-60 seconds) were performed. Continuous hemodynamic measurements and echocardiography were done at site 1. A total of 197 infants were enrolled (mean gestational age 28 ± 2 weeks). Of the 154 infants delivered by CD, 75 were assigned to UCM and 79 to DCC. Of the infants delivered by CD, neonates randomly assigned to UCM had higher superior vena cava flow and right ventricular output in the first 12 hours of life. Neonates undergoing UCM also had higher hemoglobin, delivery room temperature, blood pressure over the first 15 hours, and urine output in the first 24 hours of life. There were no differences for the 43 infants delivered by VD. This is the first randomized controlled trial demonstrating higher systemic blood flow with UCM in preterm neonates compared with DCC. UCM may be a more efficient technique to improve blood volume in premature infants delivered by CD. Copyright © 2015 by the American Academy of Pediatrics.

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. 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 ...

  14. [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.

  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. 红外辐射测温技术在煤矿高压电器检测中的应用%Infrared radiation thermometry techniques in the coal high voltage electrical detection

    Institute of Scientific and Technical Information of China (English)

    王兴举; 黄宗建; 李进曌

    2014-01-01

    Infraredradiation thermometry techniques have real-time,convenient and non-destructive,which is widely used in electrical products,temperature detection,especially in high-voltage electrical equipment due to coal mining complex run construction environment,conventional means is difficult to accurately measure the temperature changes,and infrared radiation thermometry can quickly and accurately measure high voltage electrical coal mines.This article from the infrared radiation thermometry in the coal high voltage electrical temperature measurement standpoint,focusing on the formation mechanism of the infrared radiation thermometry,testing methods and testing techniques to note,as the actual production process to provide a reliable theoretical basis.%红外辐射测温技术具备了实时、便捷以及非破坏性等特点,广泛用于电器产品温度的检测中,特别是煤矿高压电器设备由于复杂的运行施工环境,常规手段很难准确的测量温度的变化,而红外辐射测温能够迅速准确的对煤矿高压电器进行测量。本文主要从红外辐射测温技术在煤矿高压电器温度的测量方面出发,重点研究了红外辐射测温的形成机理、测试手段以及需要注意的测试技巧,为生产实际过程中提供一个可靠的理论依据。

  17. 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.

  18. 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

  19. 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.

  20. Effects of dragon's blood resin and its component loureirin B on tetrodotoxin-sensitive voltage-gated sodium currents in rat dorsal root ganglion neurons

    Institute of Scientific and Technical Information of China (English)

    LIU Xiangming; CHEN Su; YIN Shijin; MEI Zhinan

    2004-01-01

    Using whole-cell patch clamp technique on the membrane of freshly isolated dorsal root ganglion(DRG)neurons,the effects of dragon's blood resin and its important component Ioureirin B on tetrodotoxin-sensitive(TTX-S)voltage-gated sodium currents were observed.The results show that both blood resin and loureirin B could suppress TTX-S voltage-gated sodium currents in a dose-dependent way.The peak current amplitudes and the steady-state activation and inactivation curves are also made to shift by 0.05% blood resin and 0.2 mmol/L loureirin B.These results demonstrate that the effects of blood resin on TTX-S sodium current may contribute to loureirin B in blood resin.Perhaps the analgesic effect of blood resin is caused partly by loureirin B directly interfering with the nociceptive transmission of primary sensory neurons.

  1. Effects of dragon's blood resin and its component loureirin B on tetrodotoxin-sensitive voltage-gated sodium currents in rat dorsal root ganglion neurons.

    Science.gov (United States)

    Xiangming, Liu; Su, Chen; Shijin, Yin; Zhinan, Mei

    2004-08-01

    Using whole-cell patch clamp technique on the membrane of freshly isolated dorsal root ganglion (DRG) neurons, the effects of dragon's blood resin and its important component loureirin B on tetrodotoxin-sensitive (TTX-S) voltage-gated sodium currents were observed. The results show that both blood resin and loureirin B could suppress TTX-S voltage-gated sodium currents in a dose-dependent way. The peak current amplitudes and the steady-state activation and inactivation curves are also made to shift by 0.05% blood resin and 0.2 mmol/L loureirin B. These results demonstrate that the effects of blood resin on TTX-S sodium current may contribute to loureirin B in blood resin. Perhaps the analgesic effect of blood resin is caused partly by loureirin B directly interfering with the nociceptive transmission of primary sensory neurons.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  9. 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.

  10. 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...

  11. 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...

  12. 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.

  13. Desktop Software for Patch-Clamp Raw Binary Data Conversion and Preprocessing

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    2011-01-01

    Full Text Available Since raw data recorded by patch-clamp systems are always stored in binary format, electrophysiologists may experience difficulties with patch clamp data preprocessing especially when they want to analyze by custom-designed algorithms. In this study, we present desktop software, called PCDReader, which could be an effective and convenient solution for patch clamp data preprocessing for daily laboratory use. We designed a novel class module, called clsPulseData, to directly read the raw data along with the parameters recorded from HEKA instruments without any other program support. By a graphical user interface, raw binary data files can be converted into several kinds of ASCII text files for further analysis, with several preprocessing options. And the parameters can also be viewed, modified and exported into ASCII files by a user-friendly Explorer style window. The real-time data loading technique and optimized memory management programming makes PCDReader a fast and efficient tool. The compiled software along with the source code of the clsPulseData class module is freely available to academic and nonprofit users.

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    Jader Santos Cruz

    2012-10-01

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

  16. A technique for simultaneously improving the product of cutoff frequency-breakdown voltage and thermal stability of SOI SiGe HBT

    Science.gov (United States)

    Fu, Qiang; Zhang, Wan-Rong; Jin, Dong-Yue; Zhao, Yan-Xiao; Wang, Xiao

    2016-12-01

    The product of the cutoff frequency and breakdown voltage (fT×BVCEO) is an important figure of merit (FOM) to characterize overall performance of heterojunction bipolar transistor (HBT). In this paper, an approach to introducing a thin N+-buried layer into N collector region in silicon-on-insulator (SOI) SiGe HBT to simultaneously improve the FOM of fT×BVCEO and thermal stability is presented by using two-dimensional (2D) numerical simulation through SILVACO device simulator. Firstly, in order to show some disadvantages of the introduction of SOI structure, the effects of SOI insulation layer thickness (TBOX) on fT, BVCEO, and the FOM of fT×BVCEO are presented. The introduction of SOI structure remarkably reduces the electron concentration in collector region near SOI substrate insulation layer, obviously reduces fT, slightly increases BVCEO to some extent, but ultimately degrades the FOM of fT×BVCEO. Although the fT, BVCEO, and the FOM of fT×BVCEO can be improved by increasing SOI insulator SiO2 layer thickness TBOX in SOI structure, the device temperature and collector current are increased due to lower thermal conductivity of SiO2 layer, as a result, the self-heating effect of the device is enhanced, and the thermal stability of the device is degraded. Secondly, in order to alleviate the foregoing problem of low electron concentration in collector region near SOI insulation layer and the thermal stability resulting from thick TBOX, a thin N+-buried layer is introduced into collector region to not only improve the FOM of fT×BVCEO, but also weaken the self-heating effect of the device, thus improving the thermal stability of the device. Furthermore, the effect of the location of the thin N+-buried layer in collector region is investigated in detail. The result show that the FOM of fT×BVCEO is improved and the device temperature decreases as the N+-buried layer shifts toward SOI substrate insulation layer. The approach to introducing a thin N+-buried layer

  17. Extracellular Linkers Completely Transplant the Voltage Dependence from Kv1.2 Ion Channels to Kv2.1.

    Science.gov (United States)

    Elinder, Fredrik; Madeja, Michael; Zeberg, Hugo; Århem, Peter

    2016-10-18

    The transmembrane voltage needed to open different voltage-gated K (Kv) channels differs by up to 50 mV from each other. In this study we test the hypothesis that the channels' voltage dependences to a large extent are set by charged amino-acid residues of the extracellular linkers of the Kv channels, which electrostatically affect the charged amino-acid residues of the voltage sensor S4. Extracellular cations shift the conductance-versus-voltage curve, G(V), by interfering with these extracellular charges. We have explored these issues by analyzing the effects of the divalent strontium ion (Sr(2+)) on the voltage dependence of the G(V) curves of wild-type and chimeric Kv channels expressed in Xenopus oocytes, using the voltage-clamp technique. Out of seven Kv channels, Kv1.2 was found to be most sensitive to Sr(2+) (50 mM shifted G(V) by +21.7 mV), and Kv2.1 to be the least sensitive (+7.8 mV). Experiments on 25 chimeras, constructed from Kv1.2 and Kv2.1, showed that the large Sr(2+)-induced G(V) shift of Kv1.2 can be transferred to Kv2.1 by exchanging the extracellular linker between S3 and S4 (L3/4) in combination with either the extracellular linker between S5 and the pore (L5/P) or that between the pore and S6 (LP/6). The effects of the linker substitutions were nonadditive, suggesting specific structural interactions. The free energy of these interactions was ∼20 kJ/mol, suggesting involvement of hydrophobic interactions and/or hydrogen bonds. Using principles from double-layer theory we derived an approximate linear equation (relating the voltage shifts to altered ionic strength), which proved to well match experimental data, suggesting that Sr(2+) acts on these channels mainly by screening surface charges. Taken together, these results highlight the extracellular surface potential at the voltage sensor as an important determinant of the channels' voltage dependence, making the extracellular linkers essential targets for evolutionary selection.

  18. Induction of pancreatic duct cells of neonatal rats into insulin-producing cells with fetal bovine serum: A natural protocol and its use for patch clamp experiments

    Institute of Scientific and Technical Information of China (English)

    San-Hua Leng; Fu-Er Lu

    2005-01-01

    AIM: To induce the pancreatic duct cells into endocrine cells with a new natural protocol for electrophysiological study.METHODS: The pancreatic duct cells of neonatal rats were isolated, cultured and induced into endocrine oells with 15% fetal bovine serum for a period of 20 d. During this period, insulin secretion, MTT value, and morphological change of neonatal and adult pancreatic islet cells were comparatively investigated. Pancreatic β-cells were identified by morphological and electrophysiological characteristics, while ATP sensitive potassium channels(KATP), voltage-dependent potassium channels (KV), and voltage-dependent calcium channels (KCA) in β-cells were identified by patch clamp technique.RESULTS: After incubation with fetal bovine serum, the neonatal duct cells budded out, changed from duct-like cells into islet clusters. In the first 4 d, MTT value and insulin secretion increased slowly (MTT value from 0.024±0.003 to0.028±0.003, insulin secretion from 2.6±0.6to 3.1±0.8 mIU/L). Then MTT value and insulin secretion increased quickly from d 5 to d 10 (MTT value from 0.028±0.003 to 0.052±0.008, insulin secretion from 3.1±0.8to 18.3±2.6 mIU/L), then reached high plateau (MTT value >0.052±0.008, insulin secretion >18.3±2.6 mIU/L).In contrast, for the isolated adult pancreatic islet cells,both insulin release and MTT value were stable in the first 4 d (MTT value from 0.029±0.01 to 0.031±0.011,insulin secretion from 13.9±3.1 to 14.3±3.3 mIU/L), but afterwards they reduced gradually (MTT value <0.031±0.011, insulin secretion <8.2±1.5 mIU/L), and the pancrearic islet cells became dispersed, broken or atrophied correspondingly. The differentiated neonatal cells were identified as pancreatic islet cells by dithizone staining method, and pancreatic β-cells were further identified by both morphological features and electrophysiological characteristics, i.e. the existence of recording currents from KATP KV, and KCA.CONCLUSION: Islet

  19. 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...

  20. 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.

  1. 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...

  2. [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.

  3. 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.

  4. Potential clamp of isolated dialyzed neuron: minimalization of the effect of series resistance.

    Science.gov (United States)

    Stolc, S; Nemcek, V; Boska, D

    1988-06-01

    A modification of the technique of intracellular dialysis of isolated single excitable cells, such as rat spinal ganglion neuron, suitable for potential clamping of its somatic membrane is described. The advantage of the new modification is the substantial reduction of the effect of inherent resistance in series (RS) to the membrane resistance (RM) on precision of potential clamping. This is attained by reversal of cell position in the perfusion pipette resulting in an approximately tenfold reduction in the area of active membrane. The resistance of this area proportionally increased while RS remained unchanged. Hence the error in potential fixation, which is inversely proportional to the ratio RM/RS, is by approximately one order smaller with the new technique than with the original one. An essential step in the new technique is the osmotic expansion of the cell to improve the contact of the cell with the perfusion pipette in the pore and to facilitate disruption of the appropriate part of the membrane. All features and advantages of the technique of intracellular dialysis, such as simplicity, the possibility to easily change ionic composition of media, and/or to apply drugs to any side of the membrane in the same cell, etc., have been maintained.

  5. 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.

  6. 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.

  7. 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.

  8. Low-Voltage Continuous Electrospinning Patterning.

    Science.gov (United States)

    Li, Xia; Li, Zhaoying; Wang, Liyun; Ma, Guokun; Meng, Fanlong; Pritchard, Robyn H; Gill, Elisabeth L; Liu, Ye; Huang, Yan Yan Shery

    2016-11-30

    Electrospinning is a versatile technique for the construction of microfibrous and nanofibrous structures with considerable potential in applications ranging from textile manufacturing to tissue engineering scaffolds. In the simplest form, electrospinning uses a high voltage of tens of thousands volts to draw out ultrafine polymer fibers over a large distance. However, the high voltage limits the flexible combination of material selection, deposition substrate, and control of patterns. Prior studies show that by performing electrospinning with a well-defined "near-field" condition, the operation voltage can be decreased to the kilovolt range, and further enable more precise patterning of fibril structures on a planar surface. In this work, by using solution dependent "initiators", we demonstrate a further lowering of voltage with an ultralow voltage continuous electrospinning patterning (LEP) technique, which reduces the applied voltage threshold to as low as 50 V, simultaneously permitting direct fiber patterning. The versatility of LEP is shown using a wide range of combination of polymer and solvent systems for thermoplastics and biopolymers. Novel functionalities are also incorporated when a low voltage mode is used in place of a high voltage mode, such as direct printing of living bacteria; the construction of suspended single fibers and membrane networks. The LEP technique reported here should open up new avenues in the patterning of bioelements and free-form nano- to microscale fibrous structures.

  9. 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.

  10. 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.

  11. Practical considerations in voltage stability assessment

    Energy Technology Data Exchange (ETDEWEB)

    Kundur, P.; Gao, B. [Powertech Labs. Inc., Surrey, BC (Canada)

    1994-12-31

    This paper deals with some of the most important practical issues related to voltage stability assessment of large practical systems. A brief discussion of the practical aspects of voltage stability problem and prevention of voltage instability is given first, followed by descriptions of different analytical techniques and tools for voltage stability analysis. Presentations of analytical tools is focused on the VSTAB program which incorporates the modal analysis, continuation power flow, and shortest distance to instability techniques, Finally, an example case study of a practical large system is presented. The case study illustrates how modal analysis is used to determine the most effective load shedding scheme for preventing voltage instability. (author) 15 refs., 2 figs., 2 tabs.

  12. The Most Frequent Energy Theft Techniques and Hazards in Present Power Energy Consumption: Cyber Security in Smart Metering Low Voltage Network

    DEFF Research Database (Denmark)

    Czechowski, Robert; Kosek, Anna Magdalena

    2016-01-01

    One of the challenging problems when it comes to electric energy distribution is electricity theft. Regardless of whether the deed is done on a large scale or only by a single consumer, it is a problem that generates losses and its detection is not always easy. One of the crucial factors making...... the issue of electricity theft still relevant is the common physical access of the end users to the installations or meters. The article presents not only the factors encouraging energy consumers to engage in dishonest behavior and the techniques they use to achieve the intended result, but also technical...... measures aimed at detecting such actions. The discussed technical issues can prove useful in designing increasingly refined security measures and ways to detect electricity theft....

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

    Science.gov (United States)

    Murty, Balarama Vempaty

    2000-01-01

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

  14. Bone Reduction Clamp to Gain Length in Repairing Chronic Achilles Tendon Ruptures.

    Science.gov (United States)

    Buckley, Patrick S; Pedowitz, David I

    2016-11-01

    Chronic Achilles tendon ruptures occur after an unrecognized, untreated, or misdiagnosed acute Achilles tendon rupture and present a potentially debilitating injury for the patient. Various techniques have been described to reconstruct the Achilles tendon after chronic ruptures. The technique chosen depends on the length of tendon defect that is present after debridement. If the tendon gap is greater than 3 cm, additional techniques are generally used, as direct repair is often not possible. The authors present a novel intraoperative technique using pointed reduction clamps to gain and maintain length of the Achilles tendon to decrease the gap between ends of the Achilles tendon and allow for end-to-end repair when it may have otherwise not been possible. [Orthopedics. 2016; 39(6):e1223-e1225.]. Copyright 2016, SLACK Incorporated.

  15. The use of a bulldog clamp to control the dorsal vein complex during robot-assisted radical prostatectomy.

    Science.gov (United States)

    Tüfek, Ilter; Atuğ, Fatih; Argun, Burak; Keskin, Selçuk; Obek, Can; Coşkuner, Enis; Kural, Ali Riza

    2012-12-01

    Optimal control of the dorsal venous complex (DVC) is a critical step in robot-assisted radical prostatectomy (RARP). If DVC is not controlled properly, bleeding may occur during the apical dissection. On the other hand, if it is controlled well, a bloodless field is attained and, thus, a precise apical dissection and urethral division is possible. Suture ligation is the most common technique used for dorsal vein control, while some authors recommend using an endovascular stapler. Recently, athermal division and selective suture ligation technique has been reported for DVC control. We describe a new technique: Use of a bulldog clamp to control the DVC during RARP. The control of the DVC with a bulldog clamp allows a bloodless field with precise apical dissection and provides preservation of maximum urethral length while avoiding sphincteral injury.

  16. Dynamic Gain-Clamped Amplifier with Backward-Injection of a Fabry-Perot Laser

    Institute of Scientific and Technical Information of China (English)

    Chien-Hung Yeh; Chih-Yang Chen; Chien-Chung Lee; Sien Chi

    2003-01-01

    We have been experimentally demonstrated an active control technique of dynamic gain-clamped spectra for the erbium-doped fiber amplifiers (EDFA's) by a backward-injected Fabry-Perot (F-P) laser into this EDFA. In addition, employing a short length erbium-doped fiber (EDF) that not cause any gain saturation for preamplification in front of this amplifier module, it can reduce the noise figure degradation and simultaneously achieve gain variation from 11.1 dB to 0.5 dB for 10 dB input power level change.

  17. Dynamic Gain-Clamped Amplifier with Backward-Injection of a Fabry-Perot Laser

    Institute of Scientific and Technical Information of China (English)

    Chien-Hung; Yeh; Chih-Yang; Chen; Chien-Chung; Lee; Sien; Chi

    2003-01-01

    We have been experimentally demonstrated an active control technique of dynamic gain-clamped spectra for theerbium-doped fiber amplifiers (EDFA's) by a backward-injected Fabry-Perot (F-P) laser into this EDFA. In addition, employing a short length erbium-doped fiber (EDF) that not cause any gain saturation for preamplification in front of this amplifier module, it can reduce the noise figure degradation and simultaneously achieve gain variation from 11.1 dB to 0.5 dB for 10 dB input power level change.

  18. Visual patch clamp recording of neurons in thick portions of the adult spinal cord

    DEFF Research Database (Denmark)

    Munch, Anders Sonne; Smith, Morten; Moldovan, Mihai

    2010-01-01

    The study of visually identified neurons in slice preparations from the central nervous system offers considerable advantages over in vivo preparations including high mechanical stability in the absence of anaesthesia and full control of the extracellular medium. However, because of their relative...... enlargement of the spinal cord. With a conventional upright microscope in which the light condenser was carefully adjusted, we could visualize neurons present at the surface of the slice and record them with the whole-cell patch clamp technique. We show that neurons present in the middle of the preparation...

  19. Surface analysis of anodized aluminum clamps from NASA-LDEF satellite

    Science.gov (United States)

    Grammer, H. L.; Wightman, J. P.; Young, Philip R.

    1992-01-01

    Surface analysis results of selected anodized aluminum clamps containing black (Z306) and white (A276) paints which received nearly six years of Low Earth Orbit (LEO) exposure on the Long Duration Exposure Facility are reported. Surface analytical techniques, including x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and scanning electron microscopy/energy dispersive analysis by x-ray (SEM/EDAX), showed significant differences in the surface composition of these materials depending upon the position on the LDEF. Differences in the surface composition are attributed to varying amounts of atomic oxygen and vacuum ultraviolet radiation (VUV). Silicon containing compounds were the primary contaminant detected on the materials.

  20. 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.

  1. The effect of protein kinase C on voltage-gated potassium channel in pulmonary artery smooth muscle cells from rats exposed to chronic hypoxia

    Institute of Scientific and Technical Information of China (English)

    张永昶; 倪望; 张珍祥; 徐永健

    2004-01-01

    Background Chronic hypoxia can cause pulmonary hypertension and pulmonary heart disease with high mortality.The signal transduction pathway of protein kinase C (PKC) plays an important role in chronic pulmonary hypertension. So it is necessary to investigate the effect of PKC on voltage-gated potassium (K+) channels in pulmonary artery smooth muscle cells of rats exposed to chronic hypoxia.Methods Male Wistar rats were randomly divided into a control group (group A) and a chronic hypoxia group (group B). Group B received hypoxia [oxygen concentration (10±1)%] eight hours per day for four consecutive weeks. Single pulmonary artery smooth muscle cells were obtained using an acute enzyme separation method. Conventional whole cell patch clamp technique was used to record resting membrane potential, membrane capacitance and voltage-gated K+ currents. The changes in voltage-gated K+ currents before and after applying paramethoxyamphetamine (PMA) (500 nmol/L), an agonist of PKC, and PMA plus carbohydrate mixture of glucose, fructose and xylitol (GFX) (30 nmol/L), an inhibitor of PKC, were compared between the two groups. Results The resting membrane potential in group B was significantly lower than that of group A: -(29.0±4.8) mV (n=18) vs -(42.5±4.6) mV (n=35) (P0.05). The voltage-gated K+ currents were significantly inhibited by PMA in group A, and this effect was reversed by GFX. However, the voltage-gated K+ currents in group B were not affected by PMA.Conclusions The resting membrane potential and voltage-gated K+ currents in pulmonary artery smooth muscle cells from rats exposed to chronic hypoxia decreased significantly. It seems that PKC has different effects on the voltage-gated K+ currents of pulmonary artery smooth muscle cells under different conditions.

  2. COMPARISON OF VIBRATION PERFORMANCE OF A SANDWICH CLAMPED-CLAMPED BEAM WITH MAGNETS VERSUS CONVENTIONAL CONSTRAINED DAMPING TREATMENTS

    Institute of Scientific and Technical Information of China (English)

    ZhengHuiming; HeZeng; LiMing; ZhaoGaoyu

    2004-01-01

    This paper investigates how the magnetic constrained layer damping (MCLD) treatment suppresses the displacement and acceleration resonant peak of a clamped-clamped beam. Because MCLI) treatment reduces input work and gives more dissipation energy, the vibration from external excitation can be effectively suppressed.The vibration reduction effects of MCLD and other conventional constrained damping treatments are also evaluated. In many cases, using MCLD treatments can yield smaller displacement and acceleration resonant peak especially in mode 1 compared to the other treatments without greatly changing the natural frequencies of the base beam.

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

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede; Liserre, Marco

    2012-01-01

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

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

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2014-01-01

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

  5. Kinetic changes and modulation by carbamazepine on voltage-gated sodium channels in rat CA1 neurons after epilepsy

    Institute of Scientific and Technical Information of China (English)

    Guang-chun SUN; Taco WERKMAN; Wytse J WADMAN

    2006-01-01

    Aim: To study whether the functional properties of sodium channels, and subsequently the channel modulation by carbamazepine (CBZ) in hippocampal CA1 neurons can be changed after epileptic seizures. Methods: We used the acutely dissociated hippocampal CA1 pyramidal cells from epilepsy model rats 3 weeks and 3 months respectively after kainate injection, and whole-cell voltage-clamp techniques. Results: After long-term epileptic seizures, both sodium channel voltage-dependence of activation and steady-state inactivation shifted to more hyperpolarizing potentials, which resulted in the enlarged window current; the membrane density of sodium current decreased and the time constant of recovery from inactivation increased. CBZ displayed unchanged efficacy on sodium channels, with a similar binding rate to them, except that at higher concentrations, the voltage shift of inactivation was reduced. For the short-term kainate model rats, no differences were detected between the control and epilepsy groups. Conclusion: These results indicate that the properties of sodium channels in acutely dissociated hippocampal neurons could be changed following long-term epilepsy, but the alternation might not be enough to induce the channel resistance to CBZ.

  6. 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.

  7. Do not overlook an umbilical cord hernia before clamping.

    Science.gov (United States)

    Cizmeci, Mehmet Nevzat; Kanburoglu, Mehmet Kenan; Akelma, Ahmet Zulfikar; Tatli, Mustafa Mansur

    2013-08-01

    An umbilical cord hernia is a rare midline abdominal defect. These masses may be easily overlooked at birth, which may result in an intestinal injury due to careless proximal application of the cord clamp. Herein, we present a newborn infant with an umbilical cord hernia who was managed by primary closure of the lesion.

  8. A piezoelectric vibration harvester based on clamped-guided beams

    NARCIS (Netherlands)

    Wang, Z.; Matova, S.; Elfrink, R.; Jambunathan, M.; Nooijer, C. de; Schaijk, R. van; Vullers, R.J.M.

    2012-01-01

    The paper addresses the design, modeling, fabrication and experimental results of a piezoelectric energy harvester based on clamped-guided beams. The design is featured by shorter mass displacement and higher reliability than cantilever beams. Two separate sets of capacitors allow exploiting both te

  9. Visually guided whole cell patch clamp of mouse supraoptic nucleus neurons in cultured and acute conditions.

    Science.gov (United States)

    Stachniak, Tevye J E; Bourque, Charles W

    2006-07-01

    Recent advances in neuronal culturing techniques have supplied a new set of tools for studying neural tissue, providing effective means to study molecular aspects of regulatory elements in the supraoptic nucleus of the hypothalamus (SON). To combine molecular biology techniques with electrophysiological recording, we modified an organotypic culture protocol to permit transfection and whole cell patch-clamp recordings from SON cells. Neonatal mouse brain coronal sections containing the SON were dissected out, placed on a filter insert in culture medium, and incubated for at least 4 days to allow attachment to the insert. The SON was identifiable using gross anatomical landmarks, which remained intact throughout the culturing period. Immunohistochemical staining identified both vasopressinergic and oxytocinergic cells present in the cultures, typically appearing in well-defined clusters. Whole cell recordings from these cultures demonstrated that certain properties of the neonatal mouse SON were comparable to adult mouse magnocellular neurons. SON neurons in both neonatal cultures and acute adult slices showed similar sustained outward rectification above -60 mV and action potential broadening during evoked activity. Membrane potential, input resistance, and rapidly inactivating potassium current density (IA) were reduced in the cultures, whereas whole cell capacitance and spontaneous synaptic excitation were increased, perhaps reflecting developmental changes in cell physiology that warrant further study. The use of the outlined organotypic culturing procedures will allow the study of such electrophysiological properties of mouse SON using whole cell patch-clamp, in addition to various molecular, techniques that require longer incubation times.

  10. Leaky sodium channels from voltage sensor mutations in periodic paralysis, but not paramyotonia

    Science.gov (United States)

    Francis, David G.; Rybalchenko, Volodymyr; Struyk, Arie

    2011-01-01

    Background: Hypokalemic periodic paralysis (HypoPP) is associated with mutations in either the CaV1.1 calcium channel or the NaV1.4 sodium channel. Some NaV1.4 HypoPP mutations have been shown to cause an anomalous inward current that may contribute to the attacks of paralysis. Herein, we test whether disease-associated NaV1.4 mutations in previously untested homologous regions of the channel also give rise to the anomalous current. Methods: The functional properties of mutant NaV1.4 channels were studied with voltage-clamp techniques in an oocyte expression system. Results: The HypoPP mutation NaV1.4-R1132Q conducts an anomalous gating pore current, but the homologous R1448C mutation in paramyotonia congenita does not. Conclusions: Gating pore currents arising from missense mutations at arginine residues in the voltage sensor domains of NaV1.4 are a common feature of HypoPP mutant channels and contribute to the attacks of paralysis. PMID:21490317

  11. A Comparison between Electrochemical Impedance Spectroscopy and Incremental Capacity-Differential Voltage as Li-ion Diagnostic Techniques to Identify and Quantify the Effects of Degradation Modes within Battery Management Systems

    Science.gov (United States)

    Pastor-Fernández, Carlos; Uddin, Kotub; Chouchelamane, Gael H.; Widanage, W. Dhammika; Marco, James

    2017-08-01

    Degradation of Lithium-ion batteries is a complex process that is caused by a variety of mechanisms. For simplicity, ageing mechanisms are often grouped into three degradation modes (DMs): conductivity loss (CL), loss of active material (LAM) and loss of lithium inventory (LLI). State of Health (SoH) is typically the parameter used by the Battery Management System (BMS) to quantify battery degradation based on the decrease in capacity and the increase in resistance. However, the definition of SoH within a BMS does not currently include an indication of the underlying DMs causing the degradation. Previous studies have analysed the effects of the DMs using incremental capacity and differential voltage (IC-DV) and electrochemical impedance spectroscopy (EIS). The aim of this study is to compare IC-DV and EIS on the same data set to evaluate if both techniques provide similar insights into the causes of battery degradation. For an experimental case of parallelized cells aged differently, the effects due to LAM and LLI were found to be the most pertinent, outlining that both techniques are correlated. This approach can be further implemented within a BMS to quantify the causes of battery ageing which would support battery lifetime control strategies and future battery designs.

  12. Reduced Voltage Scaling in Clock Distribution Networks

    Directory of Open Access Journals (Sweden)

    Khader Mohammad

    2009-01-01

    Full Text Available We propose a novel circuit technique to generate a reduced voltage swing (RVS signals for active power reduction on main buses and clocks. This is achieved without performance degradation, without extra power supply requirement, and with minimum area overhead. The technique stops the discharge path on the net that is swinging low at a certain voltage value. It reduces active power on the target net by as much as 33% compared to traditional full swing signaling. The logic 0 voltage value is programmable through control bits. If desired, the reduced-swing mode can also be disabled. The approach assumes that the logic 0 voltage value is always less than the threshold voltage of the nMOS receivers, which eliminate the need of the low to high voltage translation. The reduced noise margin and the increased leakage on the receiver transistors using this approach have been addressed through the selective usage of multithreshold voltage (MTV devices and the programmability of the low voltage value.

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

    KAUST Repository

    Masri, Karim M.

    2016-01-20

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

  14. Synergistic Inhibition of Delayed Rectifier K+ and Voltage-Gated Na+ Currents by Artemisinin in Pituitary Tumor (GH3 Cells

    Directory of Open Access Journals (Sweden)

    Edmund Cheung So

    2017-04-01

    Full Text Available Background: Artemisinin (ART is an anti-malarial agent reported to influence endocrine function. Methods: Effects of ART on ionic currents and action potentials (APs in pituitary tumor (GH3 cells were evaluated by patch clamp techniques. Results: ART inhibited the amplitude of delayed-rectifier K+ current (IK(DR in response to membrane depolarization and accelerated the process of current inactivation. It exerted an inhibitory effect on IK(DR with an IC50 value of 11.2 µM and enhanced IK(DR inactivation with a KD value of 14.7 µM. The steady-state inactivation curve of IK(DR was shifted to hyperpolarization by 10 mV. Pretreatment of chlorotoxin (1 µM or iloprost (100 nM did not alter the magnitude of ART-induced inhibition of IK(DR in GH3 cells. ART also decreased the peak amplitude of voltage-gated Na+ current (INa with a concentration-dependent slowing in inactivation rate. Application of KMUP-1, an inhibitor of late INa, was effective at reversing ART-induced prolongation in inactivation time constant of INa. Under current-clamp recordings, ART alone reduced the amplitude of APs and prolonged the duration of APs. Conclusion: Under ART exposure, the inhibitory actions on both IK(DR and INa could be a potential mechanisms through which this drug influences membrane excitability of endocrine or neuroendocrine cells appearing in vivo.

  15. Role of low voltage activated calcium channels in neuritogenesis and active migration of embryonic neural progenitor cells.

    Science.gov (United States)

    Louhivuori, Lauri M; Louhivuori, Verna; Wigren, Henna-Kaisa; Hakala, Elina; Jansson, Linda C; Nordström, Tommy; Castrén, Maija L; Akerman, Karl E

    2013-04-15

    The central role of calcium influx and electrical activity in embryonic development raises important questions about the role and regulation of voltage-dependent calcium influx. Using cultured neural progenitor cell (NPC) preparations, we recorded barium currents through voltage-activated channels using the whole-cell configuration of the patch-clamp technique and monitored intracellular free calcium concentrations with Fura-2 digital imaging. We found that NPCs as well as expressing high-voltage-activated (HVA) calcium channels express functional low-threshold voltage-dependent calcium channels in the very early stages of differentiation (5 h to 1 day). The size of the currents recorded at -50 versus -20 mV after 1 day in differentiation was dependent on the nature of the charge carrier. Peak currents measured at -20 mV in the presence 10 mM Ca2+ instead of 10 mM Ba2+ had a tendency to be smaller, whereas the nature of the divalent species did not influence the amplitude measured at -50 mV. The T-type channel blockers mibefradil and NNC 55-0396 significantly reduced the calcium responses elicited by depolarizing with extracellular potassium, while the overall effect of the HVA calcium channel blockers was small at differentiation day 1. At differentiation day 20, the calcium responses were effectively blocked by nifedipine. Time-lapse imaging of differentiating neurospheres cultured in the presence of low-voltage-activated (LVA) blockers showed a significant decrease in the number of active migrating neuron-like cells and neurite extensions. Together, these data provide evidence that LVA calcium channels are involved in the physiology of differentiating and migrating NPCs.

  16. Modulation by extracellular pH of low- and high-voltage-activated calcium currents of rat thalamic relay neurons.

    Science.gov (United States)

    Shah, M J; Meis, S; Munsch, T; Pape, H C

    2001-03-01

    The effects of changes in the extracellular pH (pH(o)) on low-voltage- (LVA) and high-voltage- (HVA) activated calcium currents of acutely isolated relay neurons of the ventrobasal thalamic complex (VB) were examined using the whole cell patch-clamp technique. Modest extracellular alkalinization (pH 7.3 to 7.7) reversibly enlarged LVA calcium currents by 18.6 +/- 3.2% (mean +/- SE, n = 6), whereas extracellular acidification (pH 7.3 to 6.9) decreased the current by 24.8 +/- 3.1% (n = 9). Normalized current amplitudes (I/I(7.3)) fitted as a function of pH(o) revealed an apparent pK(a) of 6.9. Both, half-maximal activation voltage and steady-state inactivation were significantly shifted to more negative voltages by 2-4 mV on extracellular alkalinization and to more positive voltages by 2-3 mV on extracellular acidification, respectively. Recovery from inactivation of LVA calcium currents was not significantly affected by changes in pH(o). In contrast, HVA calcium currents were less sensitive to changes in pH(o). Although extracellular alkalinization increased maximal HVA current by 6.0 +/- 2.0% (n = 7) and extracellular acidification decreased it by 11.9 +/- 0.02% (n = 11), both activation and steady-state inactivation were only marginally affected by the moderate changes in pH(o) used in the present study. The results show that calcium currents of thalamic relay neurons exhibit different pH(o) sensitivity. Therefore activity-related extracellular pH transients might selectively modulate certain aspects of the electrogenic behavior of thalamic relay neurons.

  17. A Single-phase Diode Clamped Transformerless PV Grid-connected Inverter%一种二极管无源钳位的单相无变压器型光伏并网逆变拓扑研究

    Institute of Scientific and Technical Information of China (English)

    王金华; 顾云杰; 胡斯登; 李武华; 何湘宁; 曹丰文

    2015-01-01

    A single-phase transformerless grid-connected photovoltaic (PV) inverter topology was proposed based on diode clamped method. The proposed circuit provides an effective improvement in common-mode current rejection capability, compared with state-of-the-art dc/ac decoupled solutions such as the H5 topology. In the proposed method, an extra voltage clamped path is inserted in an ac-decoupled transformerless inverter through two passive diodes. As a result, the common-mode voltage is clamped by the dc capacitor to eliminate the possible high-frequency common-mode oscillations caused by power device parasitic capacitors, which is the major cause of leakage current in dc/ac decoupled transformerless topologies. The proposed passive clamped technique features cost effective solution with no additional active switches, in comparison with the active clamping counterpart. The performance of the proposed topology has been verified by simulation and experiment with a 2kW prototype.%提出一种基于二极管无源钳位思想的单相无变压器型光伏并网逆变器拓扑。与H5等传统电路相比,本拓扑具有更好的对地漏电流抑制能力。目前主流的单相无变压器型逆变电路普遍采用直流或交流解耦技术,阻断共模电流的流通路径。但是,功率开关上的寄生电容可能与共模电抗形成谐振回路,使得共模电流无法彻底消除。以H5拓扑为例,定量分析功率器件寄生电容影响共模电流的机理。针对这一问题,引入无源二极管钳位电路,使得共模电压被母线电容中点钳位,从而抑制了功率器件寄生电容引起的共模电压振荡,更有效地消除对地漏电流。在理论和仿真分析的基础上,通过搭建2 kW实验平台验证所提拓扑的性能。结果表明,改进拓扑相对于原拓扑而言,能更好地抑制对地漏电流,提高了无变压器型光伏并网系统的安全裕度。

  18. Voltage modulation of propagating spin waves in Fe

    Energy Technology Data Exchange (ETDEWEB)

    Nawaoka, Kohei; Shiota, Yoichi; Miwa, Shinji; Tamura, Eiiti [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); CREST, Japan Science Technology, Kawaguchi, Saitama 332-0012 (Japan); Tomita, Hiroyuki; Mizuochi, Norikazu; Shinjo, Teruya [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Suzuki, Yoshishige, E-mail: suzuki-y@mp.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); CREST, Japan Science Technology, Kawaguchi, Saitama 332-0012 (Japan); Display and Semiconductor Physics Department, Korea University, Sejong 339-700 (Korea, Republic of)

    2015-05-07

    The effect of a voltage application on propagating spin waves in single-crystalline 5 nm-Fe layer was investigated. Two micro-sized antennas were employed to excite and detect the propagating spin waves. The voltage effect was characterized using AC lock-in technique. As a result, the resonant field of the magnetostatic surface wave in the Fe was clearly modulated by the voltage application. The modulation is attributed to the voltage induced magnetic anisotropy change in ferromagnetic metals.

  19. Stray voltage mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Jamali, B.; Piercy, R.; Dick, P. [Kinetrics Inc., Toronto, ON (Canada). Transmission and Distribution Technologies

    2008-04-09

    This report discussed issues related to farm stray voltage and evaluated mitigation strategies and costs for limiting voltage to farms. A 3-phase, 3-wire system with no neutral ground was used throughout North America before the 1930s. Transformers were connected phase to phase without any electrical connection between the primary and secondary sides of the transformers. Distribution voltage levels were then increased and multi-grounded neutral wires were added. The earth now forms a parallel return path for the neutral current that allows part of the neutral current to flow continuously through the earth. The arrangement is responsible for causing stray voltage. Stray voltage causes uneven milk production, increased incidences of mastitis, and can create a reluctance to drink water amongst cows when stray voltages are present. Off-farm sources of stray voltage include phase unbalances, undersized neutral wire, and high resistance splices on the neutral wire. Mitigation strategies for reducing stray voltage include phase balancing; conversion from single to 3-phase; increasing distribution voltage levels, and changing pole configurations. 22 refs., 5 tabs., 13 figs.

  20. High voltage engineering

    CERN Document Server

    Rizk, Farouk AM

    2014-01-01

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

  1. Mitigation of Unbalanced Voltage Sags and Voltage Unbalance in CIGRE Low Voltage Distribution Network

    OpenAIRE

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar; Cecati, Carlo

    2013-01-01

    Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and net-works like this. The voltage unbala...

  2. 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.

  3. Timing of umbilical cord clamping: effect on iron endowment of the newborn and later iron status.

    Science.gov (United States)

    Chaparro, Camila M

    2011-11-01

    The optimal timing of umbilical cord clamping has been debated in the scientific literature for at least the last century, when cord clamping practices shifted from delayed towards immediate clamping. Recent research provides evidence for the beneficial effect of delayed cord clamping on infant iron status. The present review describes the physiological basis for the impact of cord clamping time on total body iron at birth and the relationship between birth body iron, as affected by cord clamping time, and iron status later in infancy. This research is discussed in the context of current clamping practices, which tend towards early cord clamping in most settings, as well as the high levels of anemia present in young infants in many countries worldwide. © 2011 International Life Sciences Institute.

  4. Effects of SDPNFLRF-amide (PF1) on voltage-activated currents in Ascaris suum muscle.

    Science.gov (United States)

    Verma, S; Robertson, A P; Martin, R J

    2009-02-01

    Helminth infections are of significant concern in veterinary and human medicine. The drugs available for chemotherapy are limited in number and the extensive use of these drugs has led to the development of resistance in parasites of animals and humans (Geerts and Gryseels, 2000; Kaplan, 2004; Osei-Atweneboana et al., 2007). The cyclooctadepsipeptide, emodepside, belongs to a new class of anthelmintic that has been released for animal use in recent years. Emodepside has been proposed to mimic the effects of the neuropeptide PF1 on membrane hyperpolarization and membrane conductance (Willson et al., 2003). We investigated the effects of PF1 on voltage-activated currents in Ascaris suum muscle cells. The whole cell voltage-clamp technique was employed to study these currents. Here we report two types of voltage-activated inward calcium currents: transient peak (I(peak)) and a steady-state (I(ss)). We found that 1microM PF1 inhibited the two calcium currents. The I(peak) decreased from -146nA to -99nA (P=0.0007) and the I(ss) decreased from -45nA to -12nA (P=0.002). We also found that PF1 in the presence of calcium increased the voltage-activated outward potassium current (from 521nA to 628nA (P=0.004)). The effect on the potassium current was abolished when calcium was removed and replaced with cobalt; it was also reduced at a higher concentration of PF1 (10microM). These studies demonstrate a mechanism by which PF1 decreases the excitability of the neuromuscular system by modulating calcium currents in nematodes. PF1 inhibits voltage-activated calcium currents and potentiates the voltage-activated calcium-dependent potassium current. The effect on a calcium-activated-potassium channel appears to be common to both PF1 and emodepside (Guest et al., 2007). It will be of interest to investigate the actions of emodepside on calcium currents to further elucidate the mechanism of action.

  5. A New Zero Voltage Switching Buck-Boost Type DC-DC Converter

    Directory of Open Access Journals (Sweden)

    Majid Delshad

    2010-03-01

    Full Text Available In this paper, a new zero voltage switching isolated buck-boost DC-DC converter with active clamp circuit is proposed. The active clamp circuit in this converter not only absorbs voltage spikes across the main switch but also provides soft switching conditions for all switches. All switches are PWM controlled which simplifies the control implementation. One of the main advantages of this converter is the that it operating can operate at high power levels while soft switching conditions exist in both buck and boost modes of converter operation. Since this converter can operate over a wide input voltage range, it can be employed in power factor correction. The experimental results obtained from a 150W prototype circuit operating at 100KHz are presented to confirm the integrity of the proposed circuit.

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

    Energy Technology Data Exchange (ETDEWEB)

    Whitaker, Bret; Barkley, Adam

    2017-05-09

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

  7. 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.

  8. 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, ...

  9. 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.

  10. 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.

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

    NARCIS (Netherlands)

    Brouwer, D.M.; Jong, de B.R.; Boer, de M.J.; Jansen, H.V.; Dijk, van J.; Krijnen, G.J.M.; Soemers, H.M.J.R.

    2009-01-01

    In this paper the design, modeling and fabrication of a precision MEMS-based clamp with a relatively large clamping force are presented. The purpose of the clamp is to mechanically fix a six-degree-of-freedom (DOF) MEMS-based sample manipulator (Brouwer et al J. Int. Soc. Precis. Eng. Nanotechnol. s

  12. MEMS-based clamp with a passive hold function for precision position retaining of micromanipulators

    NARCIS (Netherlands)

    Brouwer, Dannis Michel; de Jong, B.R.; de Boer, Meint J.; Jansen, Henricus V.; van Dijk, Johannes A.G.M.; van Dijk, Johannes; Krijnen, Gijsbertus J.M.; Soemers, Herman

    2009-01-01

    In this paper the design, modeling and fabrication of a precision MEMS-based clamp with arelatively large clamping force are presented. The purpose of the clamp is to mechanically fixa six-degree-of-freedom (DOF) MEMS-based sample manipulator (Brouwer et al J. Int. Soc. Precis. Eng. Nanotechnol. sub

  13. File list: Oth.ALL.10.Clamp.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.10.Clamp.AllCell dm3 TFs and others Clamp All cell types SRX159170,SRX15917...2,SRX159174,SRX159166,SRX159173 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.ALL.10.Clamp.AllCell.bed ...

  14. File list: Oth.ALL.05.Clamp.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.05.Clamp.AllCell dm3 TFs and others Clamp All cell types SRX159172,SRX15917...0,SRX159174,SRX159166,SRX159173 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.ALL.05.Clamp.AllCell.bed ...

  15. File list: Oth.CeL.10.Clamp.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.CeL.10.Clamp.AllCell dm3 TFs and others Clamp Cell line SRX159170,SRX159172,SRX...159174,SRX159166,SRX159173 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.CeL.10.Clamp.AllCell.bed ...

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

    Lifescience Database Archive (English)

    Full Text Available Oth.CeL.20.Clamp.AllCell dm3 TFs and others Clamp Cell line SRX159172,SRX159170,SRX...159174,SRX159166,SRX159173 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.CeL.20.Clamp.AllCell.bed ...

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

    Lifescience Database Archive (English)

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

  18. File list: Oth.ALL.20.Clamp.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.20.Clamp.AllCell dm3 TFs and others Clamp All cell types SRX159172,SRX15917...0,SRX159174,SRX159166,SRX159173 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.ALL.20.Clamp.AllCell.bed ...

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

    Lifescience Database Archive (English)

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

  20. 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

  1. Voltage verification unit

    Science.gov (United States)

    Martin, Edward J.

    2008-01-15

    A voltage verification unit and method for determining the absence of potentially dangerous potentials within a power supply enclosure without Mode 2 work is disclosed. With this device and method, a qualified worker, following a relatively simple protocol that involves a function test (hot, cold, hot) of the voltage verification unit before Lock Out/Tag Out and, and once the Lock Out/Tag Out is completed, testing or "trying" by simply reading a display on the voltage verification unit can be accomplished without exposure of the operator to the interior of the voltage supply enclosure. According to a preferred embodiment, the voltage verification unit includes test leads to allow diagnostics with other meters, without the necessity of accessing potentially dangerous bus bars or the like.

  2. From understanding cellular function to novel drug discovery: the role of planar patch-clamp array chip technology

    Directory of Open Access Journals (Sweden)

    Christophe ePy

    2011-10-01

    Full Text Available All excitable cell functions rely upon ion channels that are embedded in their plasma membrane. Perturbations of ion channel structure or function result in pathologies ranging from cardiac dysfunction to neurodegenerative disorders. Consequently, to understand the functions of excitable cells and to remedy their pathophysiology, it is important to understand the ion channel functions under various experimental conditions – including exposure to novel drug targets. Glass pipette patch-clamp is the state of the art technique to monitor the intrinsic and synaptic properties of neurons. However, this technique is labor-intensive and has low data throughput. Planar patch-clamp chips, integrated into automated systems, offer high throughputs but are limited to isolated cells from suspensions, resulting in questionable models of true physiological function, and are unsuitable for studies involving neuronal communication. Multi-electrode arrays (MEA, in contrast, have the ability to monitor network activity by measuring local field potentials from multiple extracellular sites, but specific ion channel activity is challenging to extract from these multiplexed signals. Here we describe a novel planar patch-clamp chip technology that enables the simultaneous high resolution electrophysiological interrogation of individual neurons at multiple sites in synaptically connected neuronal networks, thereby combining the advantages of MEA and patch-clamp techniques. Each neuron can be probed through an aperture that connects to a dedicated subterranean microfluidic channel. Neurons growing in networks are aligned to the apertures by physisorbed or chemisorbed chemical cues. In this review, we describe the design and fabrication process of these chips, the approach to the chemical patterning for cell placement, and present physiological data from cultured neuronal cells.

  3. Simultaneous multi-patch-clamp and extracellular-array recordings: Single neuron reflects network activity

    Science.gov (United States)

    Vardi, Roni; Goldental, Amir; Sardi, Shira; Sheinin, Anton; Kanter, Ido

    2016-11-01

    The increasing number of recording electrodes enhances the capability of capturing the network’s cooperative activity, however, using too many monitors might alter the properties of the measured neural network and induce noise. Using a technique that merges simultaneous multi-patch-clamp and multi-electrode array recordings of neural networks in-vitro, we show that the membrane potential of a single neuron is a reliable and super-sensitive probe for monitoring such cooperative activities and their detailed rhythms. Specifically, the membrane potential and the spiking activity of a single neuron are either highly correlated or highly anti-correlated with the time-dependent macroscopic activity of the entire network. This surprising observation also sheds light on the cooperative origin of neuronal burst in cultured networks. Our findings present an alternative flexible approach to the technique based on a massive tiling of networks by large-scale arrays of electrodes to monitor their activity.

  4. The firing patterns of spinal neurons: in situ patch-clamp recordings reveal a key role for potassium currents.

    Science.gov (United States)

    Winlove, Crawford I P; Roberts, Alan

    2012-10-01

    Neuron firing patterns underpin the detection and processing of stimuli, influence synaptic interactions, and contribute to the function of networks. To understand how intrinsic membrane properties determine firing patterns, we investigated the biophysical basis of single and repetitive firing in spinal neurons of hatchling Xenopus laevis tadpoles, a well-understood vertebrate model; experiments were conducted in situ. Primary sensory Rohon-Beard (RB) neurons fire singly in response to depolarising current, and dorsolateral (DL) interneurons fire repetitively. RB neurons exhibited a large tetrodotoxin-sensitive sodium current; in DL neurons, the sodium current density was significantly lower. High-voltage-activated calcium currents were similar in both neuron types. There was no evidence of persistent sodium currents, low-voltage-activated calcium currents, or hyperpolarisation-activated currents. In RB neurons, the potassium current was dominated by a tetraethylammonium-sensitive slow component (I(Ks) ); a fast component (I(Kf) ), sensitive to 4-aminopyridine, predominated in DL neurons. Sequential current-clamp and voltage-clamp recordings in individual neurons suggest that high densities of I(Ks) prevent repetitive firing; where I(Ks) is small, I(Kf) density determines the frequency of repetitive firing. Intermediate densities of I(Ks) and I(Kf) allow neurons to fire a few additional spikes on strong depolarisation; this property typifies a novel subset of RB neurons, and may activate escape responses. We discuss how this ensemble of currents and firing patterns underpins the operation of the Xenopus locomotor network, and suggest how simple mechanisms might underlie the similar firing patterns seen in the neurons of diverse species.

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

    KAUST Repository

    Masri, Karim M.

    2014-08-17

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

  6. Comparison of Multilevel Inverters for the Reduction of Common Mode Voltage

    Directory of Open Access Journals (Sweden)

    Muhammad JAMIL

    2013-02-01

    Full Text Available This paper presents a comparison between NPC (neutral point clamped and H-cascaded multilevel inverters by considering the increas or decrease of harmonics in the output line to line voltages,  phase voltages and common mode voltage. Multilevel voltage source converters are getting increased importance for applications in the medium and high voltage range. A conventional two-level PWM (pulse width modulated inverter generates high frequency common mode voltage with high dv/dt. In the same way, commonly used multilevel inverter modulation schemes generate common mode voltage. Common mode voltage may cause motor shaft voltages, bearing currents and EMI (electromagnetic interference. Common mode voltage depends not only on switching method but also on earth mass. The use of earth mass on a proper place in the circuit can reduce the common mode voltage. Sinusoidal (sine-triangle PWM scheme is being used for this purpose and simulation results are being presented in this paper by using software “Simplorer” and “Post Processor Day”.

  7. 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.

  8. Robotic partial nephrectomy with cold ischemia and on-clamp tumor extraction: recapitulating the open approach.

    Science.gov (United States)

    Rogers, Craig G; Ghani, Khurshid R; Kumar, Ramesh K; Jeong, Wooju; Menon, Mani

    2013-03-01

    We describe a reproducible technique for achieving cold ischemia with intraoperative tumor assessment during robotic partial nephrectomy (RPN) that recapitulates the open approach: intracorporeal cooling and extraction (ICE). A total of seven patients underwent the ICE modification of RPN by transperitoneal (n=5) and retroperitoneal (n=2) approaches. A Gelpoint access port was used for the camera and assistant ports. Following hilar clamping, ice slush was introduced through the Gelpoint via syringes and applied over the kidney surface. The excised tumor was immediately extracted through the Gelpoint, allowing gross margin assessment by pathology during the renorrhaphy. RPN was achieved in all cases with successful introduction of ice slush and tumor extraction while on clamp. Median RENAL nephrometry score was 8 (range: 6-10), and there was one solitary kidney. Mean cold ischemia time was 19.6 min (range: 8-37) and mean estimated blood loss was 296.4 ml (range: 50-1000). Renal parenchymal temperatures 0.5°C during any procedures. Intraoperative assessment of the excised tumor showed adequate gross margins in all cases and final pathology confirmed negative surgical margins.

  9. Artificial neural networks based controller for glucose monitoring during clamp test.

    Directory of Open Access Journals (Sweden)

    Merav Catalogna

    Full Text Available Insulin resistance (IR is one of the most widespread health problems in modern times. The gold standard for quantification of IR is the hyperinsulinemic-euglycemic glucose clamp technique. During the test, a regulated glucose infusion is delivered intravenously to maintain a constant blood glucose concentration. Current control algorithms for regulating this glucose infusion are based on feedback control. These models require frequent sampling of blood, and can only partly capture the complexity associated with regulation of glucose. Here we present an improved clamp control algorithm which is motivated by the stochastic nature of glucose kinetics, while using the minimal need in blood samples required for evaluation of IR. A glucose pump control algorithm, based on artificial neural networks model was developed. The system was trained with a data base collected from 62 rat model experiments, using a back-propagation Levenberg-Marquardt optimization. Genetic algorithm was used to optimize network topology and learning features. The predictive value of the proposed algorithm during the temporal period of interest was significantly improved relative to a feedback control applied at an equivalent low sampling interval. Robustness to noise analysis demonstrates the applicability of the algorithm in realistic situations.

  10. State-dependent FRET reports calcium- and voltage-dependent gating-ring motions in BK channels

    OpenAIRE

    Miranda, Pablo; Contreras, Jorge E.; Plested, Andrew J. R.; Sigworth, Fred J.; Holmgren, Miguel; Giraldez, Teresa

    2013-01-01

    Large-conductance voltage- and calcium-dependent potassium channels (BK, “Big K+”) are important controllers of cell excitability. In the BK channel, a large C-terminal intracellular region containing a “gating-ring” structure has been proposed to transduce Ca2+ binding into channel opening. Using patch-clamp fluorometry, we have investigated the calcium and voltage dependence of conformational changes of the gating-ring region of BK channels, while simultaneously monitoring channel conductan...

  11. Clamping stiffness and its influence on load distribution between paired internal spinal fixation devices.

    Science.gov (United States)

    Rohlmann, A; Calisse, J; Bergmann, G; Radvan, J; Mayer, H M

    1996-06-01

    The load distribution between two internal spinal fixation devices depends, besides other factors, on their stiffness. The stiffness ranges were determined experimentally for the clamps of the AO internal fixator with lateral nut and with posterior nut as well as for the clamps of the SOCON fixator. The stiffness of eight devices each differed by a factor of 3.1 for the clamp with lateral nut, by a factor of 1.5 for the clamp with posterior nut, and by a factor of 1.4 for the clamp of the SOCON fixator. For the AO clamp with lateral nut, the influence of the nut-tightening torque on the stiffness was determined. Using instrumented internal spinal fixation devices mounted to plastic vertebrae and simulating a corpectomy, the load distribution between the implants was measured for different tightening torques. It could be shown that, for the AO internal fixator whose clamps have a lateral nut, a nut-tightening torque > 5 Nm has only a negligible influence on load-sharing between the implants. Tooth damage occurs when the teeth of the clamp body and clamping jaw of the clamp with lateral nut do not gear together exactly, which leads to changes in the clamping stiffness and load-sharing between the two implants.

  12. 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.

  13. Umbilical cord clamping at birth--practice in Norwegian maternity wards.

    Science.gov (United States)

    Lundberg, Camilla; Øian, Pål; Klingenberg, Claus

    2013-11-26

    The timing and practice used for umbilical cord clamping of neonates are controversial internationally as well as in Norway. We therefore wished to investigate routines and practices for umbilical cord clamping of neonates in Norway. A web-based questionnaire was sent to heads of departments of all maternity wards in Norway (n = 52). They were asked about their practice with regard to umbilical cord clamping of neonates and whether written routines had been prepared for this purpose. We defined early umbilical cord clamping as immediate or within 30 seconds and late clamping as ≥ 1 minute or not until pulsation in the umbilical cord had ceased. Fifty (96%) of the maternity institutions returned a completed questionnaire. Twelve institutions (24%) reported to clamp the umbilical cord of full-term neonates early, and 38 (76%) reported to practise late clamping. Nineteen maternity wards (38%) followed written routines for umbilical cord clamping of full-term neonates, and among these, early umbilical cord clamping was practised in nine (47%). In the 31 maternity wards that had no written routines, early umbilical cord clamping was practised in three (10%). Twenty-seven of the maternity wards reported that the child is placed on the maternal abdomen before clamping of the umbilical cord, 14 reported that the child commonly is held below the introitus before umbilical cord clamping, and the rest did not report any consistent practice. There is wide variation in the practice for umbilical cord clamping in Norwegian maternity wards, many of which have no written guidelines. We argue that national guidelines for umbilical cord clamping of neonates should be established.

  14. Voltage stability and controllability indices for multimachine power systems

    Energy Technology Data Exchange (ETDEWEB)

    Vournas, C.D. [National Technical Univ., Athens (Greece). Electrical Energy Systems Lab.

    1995-08-01

    This paper presents a voltage stability index (VSI) and a voltage controllability index (VCI), related to the eigenvalues of mxm matrices in a multimachine power system made up of m synchronous generators and a number of infinite buses. System loads can have an arbitrary voltage sensitivity described by generalized voltage exponents. These nonlinear loads are linearized around an operating point and incorporated into a modified admittance matrix, which is subsequently reduced to the generator terminals using an efficient algorithm and sparsity techniques. The indices proposed are tested in a practical system and it is demonstrated that they provide a timely warning during a sequence of events leading to voltage collapse.

  15. Application of Double Elbow-bar Upsetting and Shape-forming Technique to Production of High-voltage Electrical Product%双肘杆镦锻成形工艺的应用

    Institute of Scientific and Technical Information of China (English)

    武泾元; 高励学

    2013-01-01

    高压电气产品中,活塞杆和接头类零件属于关键零件,且应用较多,这类零件属于长轴类带法兰件,目前,采用的加工方式是用棒料直接加工成形,材料利用率低,工艺性差.笔者分析了活塞杆和接头类零件的形状特点,认为采用双肘杆镦锻工艺制坯,解决了材料浪费问题,降低了零件制造成本,提高了零件抗拉强度.阐述了双肘杆镦锻模具设计、成形工艺、热处理工艺等方面的内容.%Piston rods and connector-type parts are critical parts in high-voltage electrical products. These parts belong to' long axis with flange' class, and the existing shape-forming process is of directly machining bar with low material utilization and efficiency. In this paper, shape features of the piston rods and connector-type parts are analyzed, and double elbow-bar upsetting technique is suggested to save material, shorten processing time, reduce manufacturing costs and increase tensile intensity of the parts. Moreover, the design of double elbow-bar upsetting mold, the molding process, and the heat treatment are discussed.

  16. Use of vacuum tubes in test instrumentation for measuring characteristics of fast high-voltage semiconductor devices

    Science.gov (United States)

    Berning, D.

    1981-01-01

    Circuits are described that permit measurement of fast events occurring in power semiconductors. These circuits were developed for the dynamic characterization of transistors used in inductive-load switching applications. Fast voltage clamping using vacuum diodes is discussed, and reference is made to a unique circuit that was built for performing nondestructive, reverse-bias, second-breakdown tests on transistors.

  17. Clamped seismic metamaterials: ultra-low frequency stop bands

    Science.gov (United States)

    Achaoui, Y.; Antonakakis, T.; Brûlé, S.; Craster, R. V.; Enoch, S.; Guenneau, S.

    2017-06-01

    The regularity of earthquakes, their destructive power, and the nuisance of ground vibration in urban environments, all motivate designs of defence structures to lessen the impact of seismic and ground vibration waves on buildings. Low frequency waves, in the range 1-10 Hz for earthquakes and up to a few tens of Hz for vibrations generated by human activities, cause a large amount of damage, or inconvenience; depending on the geological conditions they can travel considerable distances and may match the resonant fundamental frequency of buildings. The ultimate aim of any seismic metamaterial, or any other seismic shield, is to protect over this entire range of frequencies; the long wavelengths involved, and low frequency, have meant this has been unachievable to date. Notably this is scalable and the effects also hold for smaller devices in ultrasonics. There are three approaches to obtaining shielding effects: bragg scattering, locally resonant sub-wavelength inclusions and zero-frequency stop-band media. The former two have been explored, but the latter has not and is examined here. Elastic flexural waves, applicable in the mechanical vibrations of thin elastic plates, can be designed to have a broad zero-frequency stop-band using a periodic array of very small clamped circles. Inspired by this experimental and theoretical observation, all be it in a situation far removed from seismic waves, we demonstrate that it is possible to achieve elastic surface (Rayleigh) wave reflectors at very large wavelengths in structured soils modelled as a fully elastic layer periodically clamped to bedrock. We identify zero frequency stop-bands that only exist in the limit of columns of concrete clamped at their base to the bedrock. In a realistic configuration of a sedimentary basin 15 m deep we observe a zero frequency stop-band covering a broad frequency range of 0-30 Hz.

  18. High Voltage Distribution

    Science.gov (United States)

    Norbeck, Edwin; Miller, Michael; Onel, Yasar

    2010-11-01

    For detector arrays that require 5 to 10 kV at a few microamps each for hundreds of detectors, using hundreds of HV power supplies is unreasonable. Bundles of hundreds of HV cables take up space that should be filled with detectors. A typical HV module can supply 1 ma, enough current for hundreds of detectors. It is better to use a single HV module and distribute the current as needed. We show a circuit that, for each detector, measures the current, cuts off the voltage if the current exceeds a set maximum, and allows the HV to be turned on or off from a control computer. The entire array requires a single HV cable and 2 or 3 control lines. This design provides the same voltage to all of the detectors, the voltage set by the single HV module. Some additional circuitry would allow a computer controlled voltage drop between the HV and each individual detector.

  19. Effect of Clamping Rigidity of the Armour on Ballistic Performance

    Directory of Open Access Journals (Sweden)

    S. N. Dikshit

    1992-04-01

    Full Text Available Influence of the manner in which the armour plates are held during their ballistic testing on the armour performance, has been evaluated. One armour plate was clamped rigidly to the test stand while a second plate of identical composition, hardness, and dimensions was hung loosely from the target holder. Both these plates were impacted with the same type of projectiles and over the same impact velocity range. The nature of ballistic damage evaluated indicates that the manner in which the armour is held during ballistic testing has a negligible influence on its performance at least when the mass of the plate is substantially higher than that of the projectile.

  20. Pulsewidth Modulation of Neutral-Point-Clamped Indirect Matrix Converter

    DEFF Research Database (Denmark)

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

    2008-01-01

    discussed in the existing literature. Addressing the previously described issues, this paper focuses on the operational mode analysis of a three-level indirect matrix converter implemented using a neutral-point-clamped inversion stage and the design of a number of PWM and modulation ratio compensation...... schemes for controlling the converter with improved waveform quality. The performances and practicalities of the designed schemes are verified in simulation and experimentally using an implemented laboratory prototype with some representative results captured and presented in this paper....

  1. Low-voltage gyrotrons

    Science.gov (United States)

    Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.

    2013-03-01

    For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5-10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%-2% in the submillimeter wavelength region).

  2. High voltage and electrical insulation engineering

    CERN Document Server

    Arora, Ravindra

    2011-01-01

    "The book is written for students as well as for teachers and researchers in the field of High Voltage and Insulation Engineering. It is based on the advance level courses conducted at TU Dresden, Germany and Indian Institute of Technology Kanpur, India. The book has a novel approach describing the fundamental concept of field dependent behavior of dielectrics subjected to high voltage. There is no other book in the field of high voltage engineering following this new approach in describing the behavior of dielectrics. The contents begin with the description of fundamental terminology in the subject of high voltage engineering. It is followed by the classification of electric fields and the techniques of field estimation. Performance of gaseous, liquid and solid dielectrics under different field conditions is described in the subsequent chapters. Separate chapters on vacuum as insulation and the lightning phenomenon are included"--

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    -source inverter are introduced here for operating the proposed inverter with voltage buck–boost energy conversion ability and five-level phase voltage switching. These characteristic features are in fact always ensured at the inverter terminal output by simply adopting a properly designed carrier modulation...... scheme, which always inserts two partial shoot-through states per half carrier cycle for smooth balanced operation. Theoretical findings and practical issues identified are eventually verified by constructing a scaled down laboratory prototype for testing....

  4. Harmonic analysis of DC capacitor current in sinusoidal and space-vector modulated neutral-point-clamped inverters

    Indian Academy of Sciences (India)

    Gopalakrishnan K S; G Narayanan

    2015-08-01

    The voltage ripple and power loss in the DC-capacitor of a voltage source inverter depend on the harmonic currents flowing through the capacitor. This paper presents a double Fourier series based analysis of the harmonic contents of the DC capacitor current in a three-level neutral-point clamped (NPC) inverter, modulated with sine-triangle pulse-width modulation (SPWM) or conventional space vector pulse-width modulation (CSVPWM) schemes. The analytical results are validated experimentally on a 3-kVA three-level inverter prototype. The capacitor current in an NPC inverter has a periodicity of 120º at the fundamental or modulation frequency. Hence, this current contains third-harmonic and triplen-frequency components, apart from switching frequency components. The harmonic components vary with modulation index and power factor for both PWM schemes. The third harmonic current decreases with increase in modulation index and also decreases with increase in power factor in case of both PWM methods. In general, the third harmonic content is higher with SPWM than with CSVPWM at a given operating condition. Also, power loss and voltage ripple in the DC capacitor are estimated for both the schemes using the current harmonic spectrum and equivalent series resistance (ESR) of the capacitor.

  5. Effects of (−-Gallocatechin-3-Gallate on Tetrodotoxin-Resistant Voltage-Gated Sodium Channels in Rat Dorsal Root Ganglion Neurons

    Directory of Open Access Journals (Sweden)

    Jian-Min Jiang

    2013-05-01

    Full Text Available The (−-gallocatechin-3-gallate (GCG concentration in some tea beverages can account for as much as 50% of the total catechins. It has been shown that catechins have analgesic properties. Voltage-gated sodium channels (Nav mediate neuronal action potentials. Tetrodotoxin inhibits all Nav isoforms, but Nav1.8 and Nav1.9 are relatively tetrodotoxin-resistant compared to other isoforms and functionally linked to nociception. In this study, the effects of GCG on tetrodotoxin-resistant Na+ currents were investigated in rat primary cultures of dorsal root ganglion neurons via the whole-cell patch-clamp technique. We found that 1 μM GCG reduced the amplitudes of peak current density of tetrodotoxin-resistant Na+ currents significantly. Furthermore, the inhibition was accompanied by a depolarizing shift of the activation voltage and a hyperpolarizing shift of steady-state inactivation voltage. The percentage block of GCG (1 μM on tetrodotoxin-resistant Na+ current was 45.1% ± 1.1% in 10 min. In addition, GCG did not produce frequency-dependent block of tetrodotoxin-resistant Na+ currents at stimulation frequencies of 1 Hz, 2 Hz and 5 Hz. On the basis of these findings, we propose that GCG may be a potential analgesic agent.

  6. Improving Low Voltage Ride Through Capability of Wind Generators Using Dynamic Voltage Restorer

    Science.gov (United States)

    Sivasankar, Gangatharan; Suresh Kumar, Velu

    2014-08-01

    The increasing wind power integration with power grid has forced the situation to improve the reliability of wind generators for stable operation. One important problem with induction generator based wind farm is its low ride through capability to the grid voltage disturbance. Any disturbance such as voltage dip may cause wind farm outages. Since wind power contribution is in predominant percentage, such outages may lead to stability problem. The proposed strategy is to use dynamic voltage controller (DVR) to compensate the voltage disturbance. The DVR provides the wind generator the ability to remain connected in grid and improve the reliability. The voltage dips due to symmetrical and unsymmetrical faults are considered for analysis. The vector control scheme is employed for fault compensation which uses software phase locked loop scheme and park dq0 transformation technique. Extensive simulation results are included to illustrate the control and operation of DVR.

  7. Blockade of the voltage-dependent sodium current in isolated rat hippocampal neurons by tetrodotoxin and lidocaine.

    Science.gov (United States)

    Kaneda, M; Oyama, Y; Ikemoto, Y; Akaike, N

    1989-04-10

    The effects of tetrodotoxin and lidocaine on the voltage-dependent sodium current (INa) were studied in the CA1 pyramidal neurons isolated acutely from rat hippocampus using a 'concentration-clamp' technique which combines the intracellular perfusion with a rapid external solution change within a few ms. Tetrodotoxin (TTX) exerted its inhibitory action in time- and dose-dependent manner on the peak amplitude of INa without any apparent effects on both the current activation and inactivation processes of the current. The time course for reaching a steady-state of the inhibitory action shortened with increasing TTX concentration, but the time course of recovery from the inhibition after washing out the toxin was quite the same at any concentrations used. Lidocaine also inhibited dose-dependently the INa, though with slightly accelerating both the activation and inactivation processes. The time courses for reaching the steady-state inhibition and the recovery from the inhibition were much shorter than those in the case of TTX. The results indicate that the voltage-dependent sodium channel of mammalian brain neuron is TTX-sensitive as well as that of peripheral neuron and that the mode of TTX inhibition on the INa is quite different from that of lidocaine.

  8. Delayed clamping of the umbilical cord after delivery and implications for public cord blood banking.

    Science.gov (United States)

    Allan, David S; Scrivens, Nicholas; Lawless, Tiffany; Mostert, Karen; Oppenheimer, Lawrence; Walker, Mark; Petraszko, Tanya; Elmoazzen, Heidi

    2016-03-01

    Public banking of umbilical cord blood units (CBUs) containing higher numbers of cells ensures timely engraftment after transplantation for increasing numbers of patients. Delayed clamping of the umbilical cord after birth may benefit some infants by preventing iron deficiency. Implications of delayed cord clamping for public cord blood banking remains unclear. CBUs collected by Canadian Blood Services at one collection site between November 1, 2014, and March 17, 2015, were analyzed. The delay in cord clamping after birth was timed and classified as "no delay," 20 to 60 seconds, more than 60 seconds, or more than 120 seconds. Of 367 collections, 100 reported no delay in clamping while clamping was delayed by 20 to 60 seconds (n = 69), more than 60 seconds (n = 98), or more than 120 seconds (n = 100) in the remaining cases. The mean volume and total nucleated cells (TNCs) in units with no delay in clamping were significantly greater than mean volumes for all categories of delayed clamping (Tukey's test, p clamping was delayed (p = 5.5 × 10(-8) ). The difference was most marked for cords that were clamped more than 120 seconds after delivery (6.2% compared with 39%). Delayed cord clamping greatly diminishes the volume and TNC count of units collected for a public cord blood bank. Creating an inventory of CBUs with high TNC content may take more time than expected. © 2015 AABB.

  9. 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.

  10. Randomised trial of cord clamping and initial stabilisation at very preterm birth.

    Science.gov (United States)

    Duley, Lelia; Dorling, Jon; Pushpa-Rajah, Angela; Oddie, Sam J; Yoxall, Charles William; Schoonakker, Bernard; Bradshaw, Lucy; Mitchell, Eleanor J; Fawke, Joe Anthony

    2017-09-18

    For very preterm births, to compare alternative policies for umbilical cord clamping and immediate neonatal care. Parallel group randomised (1:1) trial, using sealed opaque numbered envelopes. Eight UK tertiary maternity units. 261 women expected to have a live birth before 32 weeks, and their 276 babies. Cord clamping after at least 2 min and immediate neonatal care with cord intact, or clamping within 20 s and immediate neonatal care after clamping. Intraventricular haemorrhage (IVH), death before discharge. 132 women (137 babies) were allocated clamping ≥2 min and neonatal care cord intact, and 129 (139) clamping ≤20 s and neonatal care after clamping; six mother-infant dyads were excluded (2, 4) as birth was after 35(+6) weeks, one withdrew (death data only available) (0, 1). Median gestation was 28.9 weeks for those allocated clamping ≥2 min, and 29.2 for those allocated clamping ≤20 s. Median time to clamping was 120 and 11 s, respectively. 7 of 135 infants (5.2%) allocated clamping ≥2 min died and 15 of 135 (11.1%) allocated clamping ≤20 s; risk difference (RD) -5.9% (95% CI -12.4% to 0.6%). Of live births, 43 of 134 (32%) had IVH vs 47 of 132 (36%), respectively; RD -3.5% (-14.9% to 7.8%). There were no clear differences in other outcomes for infants or mothers. This is promising evidence that clamping after at least 2 min and immediate neonatal care with cord intact at very preterm birth may improve outcome; a large trial is urgently needed. ISRCTN 21456601. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  11. 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.

  12. Patch-clamp detection of macromolecular translocation along nuclear pores

    Directory of Open Access Journals (Sweden)

    Bustamante J.O.

    1998-01-01

    Full Text Available The present paper reviews the application of patch-clamp principles to the detection and measurement of macromolecular translocation along the nuclear pores. We demonstrate that the tight-seal 'gigaseal' between the pipette tip and the nuclear membrane is possible in the presence of fully operational nuclear pores. We show that the ability to form a gigaseal in nucleus-attached configurations does not mean that only the activity of channels from the outer membrane of the nuclear envelope can be detected. Instead, we show that, in the presence of fully operational nuclear pores, it is likely that the large-conductance ion channel activity recorded derives from the nuclear pores. We conclude the technical section with the suggestion that the best way to demonstrate that the nuclear pores are responsible for ion channel activity is by showing with fluorescence microscopy the nuclear translocation of ions and small molecules and the exclusion of the same from the cisterna enclosed by the two membranes of the envelope. Since transcription factors and mRNAs, two major groups of nuclear macromolecules, use nuclear pores to enter and exit the nucleus and play essential roles in the control of gene activity and expression, this review should be useful to cell and molecular biologists interested in understanding how patch-clamp can be used to quantitate the translocation of such macromolecules into and out of the nucleus

  13. Molecular force spectroscopy with a DNA origami-based nanoscopic force clamp.

    Science.gov (United States)

    Nickels, Philipp C; Wünsch, Bettina; Holzmeister, Phil; Bae, Wooli; Kneer, Luisa M; Grohmann, Dina; Tinnefeld, Philip; Liedl, Tim

    2016-10-21

    Forces in biological systems are typically investigated at the single-molecule level with atomic force microscopy or optical and magnetic tweezers, but these techniques suffer from limited data throughput and their requirement for a physical connection to the macroscopic world. We introduce a self-assembled nanoscopic force clamp built from DNA that operates autonomously and allows massive parallelization. Single-stranded DNA sections of an origami structure acted as entropic springs and exerted controlled tension in the low piconewton range on a molecular system, whose conformational transitions were monitored by single-molecule Förster resonance energy transfer. We used the conformer switching of a Holliday junction as a benchmark and studied the TATA-binding protein-induced bending of a DNA duplex under tension. The observed suppression of bending above 10 piconewtons provides further evidence of mechanosensitivity in gene regulation.

  14. Device for monitoring cell voltage

    Science.gov (United States)

    Doepke, Matthias [Garbsen, DE; Eisermann, Henning [Edermissen, DE

    2012-08-21

    A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

  15. High voltage pulse generator

    Science.gov (United States)

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  16. TFE and Spt4/5 open and close the RNA polymerase clamp during the transcription cycle.

    Science.gov (United States)

    Schulz, Sarah; Gietl, Andreas; Smollett, Katherine; Tinnefeld, Philip; Werner, Finn; Grohmann, Dina

    2016-03-29

    Transcription is an intrinsically dynamic process and requires the coordinated interplay of RNA polymerases (RNAPs) with nucleic acids and transcription factors. Classical structural biology techniques have revealed detailed snapshots of a subset of conformational states of the RNAP as they exist in crystals. A detailed view of the conformational space sampled by the RNAP and the molecular mechanisms of the basal transcription factors E (TFE) and Spt4/5 through conformational constraints has remained elusive. We monitored the conformational changes of the flexible clamp of the RNAP by combining a fluorescently labeled recombinant 12-subunit RNAP system with single-molecule FRET measurements. We measured and compared the distances across the DNA binding channel of the archaeal RNAP. Our results show that the transition of the closed to the open initiation complex, which occurs concomitant with DNA melting, is coordinated with an opening of the RNAP clamp that is stimulated by TFE. We show that the clamp in elongation complexes is modulated by the nontemplate strand and by the processivity factor Spt4/5, both of which stimulate transcription processivity. Taken together, our results reveal an intricate network of interactions within transcription complexes between RNAP, transcription factors, and nucleic acids that allosterically modulate the RNAP during the transcription cycle.

  17. Percutaneous clamping of spiral and oblique fractures of the tibial shaft: a safe and effective reduction aid during intramedullary nailing.

    Science.gov (United States)

    Collinge, Cory A; Beltran, Michael J; Dollahite, Henry A; Huber, Florian G

    2015-06-01

    The reduction of tibial shaft fractures during intramedullary nailing is important if limb alignment is to be restored and successful clinical outcomes are expected. We have used a percutaneously applied (or open) clamp or clamps to achieve and maintain reduction during nailing of all amendable tibial shaft fractures. In this article, we describe the technique and preliminary results comparing closed, simple spiral and oblique tibial shaft fractures (OTA 42-A1 and A2) managed with percutaneous clamp-assisted nailing (CAN) versus nailing using manual reduction (MRN) held by the surgical team. In the MRN group, there were an increased fracture gap (P = 0.04) and trends toward malalignment (P = 0.07) and healing time (P = 0.06) compared with the CAN group. There were also trends in clinical; no wound complications occurred in either group. We have found that percutaneous CAN of closed, simple spiral and oblique tibial shaft fractures seems safe and allows for early predictable union with reproducible alignment compared with nailing using MRN.

  18. A comparison of 15 Hz sine on-line and off-line magnetic stimulation affecting the voltage-gated sodium channel currents of prefrontal cortex pyramidal neurons

    Science.gov (United States)

    Zheng, Yu; Dong, Lei; Gao, Yang; Dou, Jun-Rong; Li, Ze-yan

    2016-10-01

    Combined with the use of patch-clamp techniques, repetitive transcranial magnetic stimulation (rTMS) has proven to be a noninvasive neuromodulation tool that can inhibit or facilitate excitability of neurons after extensive research. The studies generally focused on the method: the neurons are first stimulated in an external standard magnetic exposure device, and then moved to the patch-clamp to record electrophysiological characteristics (off-line magnetic exposure). Despite its universality, real-time observation of the effects of magnetic stimulation on the neurons is more effective (on-line magnetic stimulation). In this study, we selected a standard exposure device for magnetic fields acting on mouse prefrontal cortex pyramidal neurons, and described a new method that a patch-clamp setup was modified to allow on-line magnetic stimulation. By comparing the off-line exposure and on-line stimulation of the same magnetic field intensity and frequency affecting the voltage-gated sodium channel currents, we succeeded in proving the feasibility of the new on-line stimulation device. We also demonstrated that the sodium channel currents of prefrontal cortex pyramidal neurons increased significantly under the 15 Hz sine 1 mT, and 2 mT off-line magnetic field exposure and under the 1 mT and 2 mT on-line magnetic stimulation, and the rate of acceleration was most significant on 2 mT on-line magnetic stimulation. This study described the development of a new on-line magnetic stimulator and successfully demonstrated its practicability for scientific stimulation of neurons.

  19. 五相电压源逆变器的空间矢量脉宽调制方法研究%Research of Space Vector PWM Techniques for Five-phase Voltage Source Inverter

    Institute of Scientific and Technical Information of China (English)

    高宏伟; 杨贵杰; 刘剑

    2014-01-01

    To improve the DC bus voltage utilization of five-phase voltage source inverter (VSI) and reduce the harmonic component of output phase voltages, a space vector pulse width modulation (SVPWM) algorithm of five-phase VSI based on adjacent four voltage vectors was proposed. According to the value of modulation index, the modulation range could be divided into sine modulation region and non-sine modulation region. In sine modulation region, the output phase voltages are standard sine waves without any harmonic component through allocating the action time of space vector appropriately. In non-sine modulation region, through optimizing the voltage vector in harmonic subspace, not only the DC bus voltage utilization is improved effectively, but also the harmonic component of output phase voltages is minimized. Simulation and experimental results verify the correctness and feasibility of the proposed algorithm.%为提高五相电压源逆变器(voltage source inverter,VSI)的直流母线电压利用率,减少输出相电压中所含的谐波分量,提出一种改进的基于最近四矢量的五相 VSI 空间矢量脉宽调制算法。根据调制系数的不同,将整个调制范围分为正弦调制区和非正弦调制区。在正弦调制区,通过合理分配空间矢量的作用时间,使得输出相电压为标准正弦波形,不含有任何谐波成分;在非正弦调制区,通过对谐波子空间内的电压矢量进行优化控制,在进一步提高直流母线电压利用率的同时,保证输出相电压中所含谐波分量更少,使逆变器工作在最优状态。仿真和实验结果验证了所提算法的正确性和可行性。

  20. 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.