WorldWideScience

Sample records for clamps

  1. 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.

  2. Servodrive Clamping Unit

    OpenAIRE

    Štefánek, Tomáš

    2009-01-01

    Design servodrive clamping unit with pneumatic or mechanic multiplier. Unit has be instrumental to strength clamp parts in tension technical machines. Frame unit’s is complicate from massive and movable clamping board and is self-supporting. Unit has be solution like incorporated modulus. Target is proposal main driving period for movable clamping board. Work up proposal constructional solution, drawing listings, production drawing of the three engaged part of, BOM. Computational report must ...

  3. 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.

  4. Insulated pipe clamp design

    International Nuclear Information System (INIS)

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

  5. Laser beam guard clamps

    Science.gov (United States)

    Dickson, Richard K.

    2010-09-07

    A quick insert and release laser beam guard panel clamping apparatus having a base plate mountable on an optical table, a first jaw affixed to the base plate, and a spring-loaded second jaw slidably carried by the base plate to exert a clamping force. The first and second jaws each having a face acutely angled relative to the other face to form a V-shaped, open channel mouth, which enables wedge-action jaw separation by and subsequent clamping of a laser beam guard panel inserted through the open channel mouth. Preferably, the clamping apparatus also includes a support structure having an open slot aperture which is positioned over and parallel with the open channel mouth.

  6. Clamping characteristics study on different types of clamping unit

    International Nuclear Information System (INIS)

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

  7. Neuronal Response Clamp

    Directory of Open Access Journals (Sweden)

    Avner Wallach

    2011-04-01

    Full Text Available Responses of individual neurons to ongoing input are highly variable, reflecting complex threshold dynamics. Experimental access to this threshold dynamics is required in order to fully characterize neuronal input-output relationships. The challenge is practically intractable using present day experimental paradigms due to the cumulative, nonlinear interactions involved. Here we introduce the Neuronal Response Clamp, a closed-loop technique enabling control over the instantaneous response probability of the neuron. The potential of the technique is demonstrated by showing direct access to threshold dynamics of cortical neuron in-vitro using extracellular recording and stimulation, over timescales ranging from seconds to many hours. Moreover, the method allowed us to expose the sensitivity of threshold dynamics to spontaneous input from the network in which the neuron is embedded. The Response Clamp technique follows the rationale of the voltage-clamp and dynamic-clamp approaches, extending it to the neuron's spiking behavior. The general framework offered here is applicable in the study of other neural systems, beyond the single neuron level.

  8. Cantilever clamp fitting

    Science.gov (United States)

    Melton, Patrick B. (Inventor)

    1989-01-01

    A device is disclosed for sealing and clamping a cylindrical element which is to be attached to an object such as a wall, a pressurized vessel or another cylindrical element. The device includes a gland having an inner cylindrical wall, which is threaded at one end and is attached at a bendable end to a deformable portion, which in turn is attached to one end of a conical cantilever structure. The other end of the cantilever structure connects at a bendable area to one end of an outer cylindrical wall. The opposite end of cylindrical wall terminates in a thickened portion, the radially outer surface of which is adapted to accommodate a tool for rotating the gland. The terminal end of cylindrical wall also includes an abutment surface, which is adapted to engage a seal, which in turn engages a surface of a receiver. The receiver further includes a threaded portion for engagement with the threaded portion of gland whereby a tightening rotation of gland relative to receiver will cause relative movement between cylindrical walls and of gland. This movement causes a rotation of the conical structure and thus a bending action at bending area and at the bending end of the upper end of inner cylindrical wall. These rotational and bending actions result in a forcing of the deformable portion radially inwardly so as to contact and deform a pipe. This forcible contact creates a seal between gland and pipe, and simultaneously clamps the pipe in position.

  9. PKM Mechatronic Clamping Adaptive Device

    OpenAIRE

    Alberto Borboni; Francesco Aggogeri; Angelo Merlo; Nicola Pellegrini; Cinzia Amici

    2015-01-01

    This study proposes a novel adaptive fixturing device based on active clamping systems for smart micropositioning of thin-walled precision parts. The modular architecture and the structure flexibility make the system suitable for various industrial applications. The proposed device is realized as a Parallel Kinematic Machine (PKM), opportunely sensorized and controlled, able to perform automatic error-free workpiece clamping procedures, drastically reducing the overall fixturing set-up time. ...

  10. Temperature compensating stiff pipe clamp

    International Nuclear Information System (INIS)

    A new type of non-integral pipe attachment for nuclear piping seismic restraint that allows the pipe free thermal diametric expansion without constraint when using dissimilar pipe and clamp material is described. The clamp has a high spring rate that can be controlled by variable stiffness parameters in the design. Described in detail are thermal constraint stress, load stress distribution, spring rates, load angles and design philosophy. Analytical methods of code design, fabrication techniques, cost benefits and lead time reduction techniques are presented. 5 refs

  11. 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.

  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/Cla...mp.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. Dynamics of Open DNA Sliding Clamps.

    Directory of Open Access Journals (Sweden)

    Aaron J Oakley

    Full Text Available A range of enzymes in DNA replication and repair bind to DNA-clamps: torus-shaped proteins that encircle double-stranded DNA and act as mobile tethers. Clamps from viruses (such as gp45 from the T4 bacteriophage and eukaryotes (PCNAs are homotrimers, each protomer containing two repeats of the DNA-clamp motif, while bacterial clamps (pol III β are homodimers, each protomer containing three DNA-clamp motifs. Clamps need to be flexible enough to allow opening and loading onto primed DNA by clamp loader complexes. Equilibrium and steered molecular dynamics simulations have been used to study DNA-clamp conformation in open and closed forms. The E. coli and PCNA clamps appear to prefer closed, planar conformations. Remarkably, gp45 appears to prefer an open right-handed spiral conformation in solution, in agreement with previously reported biophysical data. The structural preferences of DNA clamps in solution have implications for understanding the duty cycle of clamp-loaders.

  14. 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.

  15. 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.

  16. Protein folding in a force clamp

    Science.gov (United States)

    Cieplak, Marek; Szymczak, P.

    2006-05-01

    Kinetics of folding of a protein held in a force clamp are compared to an unconstrained folding. The comparison is made within a simple topology-based dynamical model of ubiquitin. We demonstrate that the experimentally observed variations in the end-to-end distance reflect microscopic events during folding. However, the folding scenarios in and out of the force clamp are distinct.

  17. Dynamic clamp with StdpC software

    Science.gov (United States)

    2011-01-01

    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, 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 via 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 cell impalement. PMID:21372819

  18. Inequalities for the Vibrating Clamped Plate Problem

    OpenAIRE

    MCHALE, K.P.

    2001-01-01

    We study the eigenvalues of the vibrating clamped plate problem. We have made improvements on the bounds of the ratios of the eigenvalues of the biharmonic operator (clamped plate) using the methods of Payne, Polya, and Weinberger. The difference in our proof lies mainly with the trial functions and the orthogonality arguments. While Payne, Polya, and Weinberger and Hile and Yeh project away components along u1,u2,...,uk to meet the orthogonality conditions,we use a translation/rotation ...

  19. Protein folding in a force-clamp

    Science.gov (United States)

    Cieplak, Marek; Szymczak, Piotr

    2006-03-01

    Kinetics of folding of a protein held in a force-clamp are compared to an unconstrained folding. The comparison is made within a simple topology-based dynamical model of ubiquitin. We demonstrate that the experimentally observed rapid changes in the end-to-end distance mirror microscopic events during folding. However, the folding scenarios in and out of the force-clamp are distinct.

  20. Protein folding in a force-clamp

    OpenAIRE

    Cieplak, Marek; Szymczak, Piotr

    2006-01-01

    Kinetics of folding of a protein held in a force-clamp are compared to an unconstrained folding. The comparison is made within a simple topology-based dynamical model of ubiquitin. We demonstrate that the experimentally observed variations in the end-to-end distance reflect microscopic events during folding. However, the folding scenarios in and out of the force-clamp are distinct.

  1. 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.

  2. An Ultrasonic Clamp for Bloodless Partial Nephrectomy

    Science.gov (United States)

    Lafon, Cyril; Bouchoux, Guillaume; Murat, François Joseph; Birer, Alain; Theillère, Yves; Chapelon, Jean Yves; Cathignol, Dominique

    2007-05-01

    Maximum conservation of the kidney is preferable through partial nephrectomy for patients at risk of disease recurrence of renal cancers. Haemostatic tools are needed in order to achieve bloodless surgery and reduce post surgery morbidity. Two piezo-ceramic transducers operating at a frequency of 4 MHz were mounted on each arm of a clamp. When used for coagulation purposes, two transducers situated on opposite arms of the clamp were driven simultaneously. Heat delivery was optimized as each transducers mirrored back to targeted tissues the wave generated by the opposite transducer. Real-time treatment monitoring with an echo-based technique was also envisaged with this clamp. Therapy was periodically interrupted so one transducer could generate a pulse. The echo returning from the opposite transducer was treated. Coagulation necroses were obtained in vitro on substantial thicknesses (23-38mm) of pig liver over exposure durations ranging from 30s to 130s, and with acoustic intensities of less than 15W/cm2 per transducer. Both kidneys of two pigs were treated in vivo with the clamp (14.5W/cm2 for 90s), and the partial nephrectomies performed proved to be bloodless. In vitro and in vivo, wide transfixing lesions corresponded to an echo energy decrease superior to -10dB and parabolic form of the time of flight versus treatment time. In conclusion, this ultrasound clamp has proven to be an excellent mean for achieving monitored haemostasis in kidney.

  3. 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.

  4. 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

  5. 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.

  6. Multilevel-clamped multilevel converters (MLC2)

    DEFF Research Database (Denmark)

    Rodriguez, Pedro; Bellar, Maria Dias; Muñoz-Aguliar, Raúl Santiago; Busquets-Monge, Sergio; Blaabjerg, Frede

    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 ...

  7. 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....

  8. π-Clamp-mediated cysteine conjugation

    Science.gov (United States)

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

    2016-02-01

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

  9. Hyperinsulinemic Euglycemic clamp for cardiac PET

    International Nuclear Information System (INIS)

    The aim of this study was to assess the adequacy of Hyperinsulinemic Euglycaemic clamp to yield technically adequate and clinically meaningful cardiac scans. The F- 18 Fluorodeoxyglucose scans obtained in diabetic patients are of sub-optimal quality as high level of glucose competes with radioactive Fluorodeoxyglucose for cardiac uptake. Thus to allow quick stabilization of metabolic environment and to get superior quality images, insulin clamp is an accepted technique. Thirty patients (20 males and 5 females) with ages ranging from 43 to 69 years, who were referred for post-myocardial infarction estimation of myocardial viability, were evaluated in this study. All patients reported for the test after 6 hours of fasting. At first myocardial perfusion studies were carried out in all patients with Tc-99m Tetrofosmin on a GE dual head gamma camera. Blood glucose levels were checked. The blood sugar levels in the patients were in the range of 130 - 190 mg%. Insulin clamp was applied depending upon the glucose level obtained, according to ASNC guidelines for PET Myocardial Glucose Metabolism and Perfusion Imaging. On stabilization of blood glucose levels, 10 mCi of F-18 FDG was injected and imaging was performed at 1 hour on a dedicated 16 slice STE GE PET -- CT scanner. Three patients had incidence of hypoglycemia as a side effect during the procedure, their blood sugar falling to 40 mg%. They were treated with 25ml of 25% dextrose intravenously following which there was stabilization of blood sugar. Entire procedure including Tetrofosmin imaging took approximately 4-6 hours. Good quality images were obtained after the use of insulin clamp. Infusion of insulin and glucose gives stable plasma glucose levels during imaging. The insulin clamp technique makes it possible to adjust and maintain a metabolic steady state during the PET study. It does not alter F-18 FDG uptake patterns in different myocardial areas and gives superior quality images. The technique is safe and

  10. Condition of chromic acid anodized aluminum clamps flown

    Science.gov (United States)

    Plagemann, W. L.

    1991-01-01

    A survey of the condition of the chromic acid anodized (CAA) coating on selected LDEF tray clamps was carried out. Measurements of solar absorptance and thermal emittance were carried out at multiple locations on both the space exposed and spacecraft facing sides of the clamps. Multiple clamps from each available angle relative to the ram direction were examined. The diffuse component of the reflectance spectrum was measured for a selected subset of the clamps. The thickness of the CAA was determined for a small set of clamps. Examples of variation in integrity of the coatings from leading to trailing edge will be shown.

  11. Biological cell controllable patch-clamp microchip

    Science.gov (United States)

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

    2010-12-01

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

  12. Design of a hot clamp for small diameter LMFBR piping

    International Nuclear Information System (INIS)

    In order to evaluate the feasibility of using a strap-type clamp on breeder reactor small diameter piping, a series of analyses were conducted to determine the thermal and mechanical stresses induced in the pipe by the clamp. The effect of using a thin layer of insulation of varying thickness between the pipe and clamp was also investigated. A thermal analysis of the pipe and clamp was conducted for each thermal transient rate. Various insulation values ranging from metal-to-metal condition to perfect insulation between the pipe and clamp were analyzed to determine the effect of insulating the pipe from the clamp. An axisymmetric finite element model was used to determine the axial thermal and stress patterns

  13. Combination Space Station Handrail Clamp and Pointing Device

    Science.gov (United States)

    Hughes, Stephen J. (Inventor)

    1999-01-01

    A device for attaching an experiment carrier to a space station handrail is provided. The device has two major components, a clamping mechanism for attachment to a space station handrail, and a pointing carrier on which an experiment package can be mounted and oriented. The handrail clamp uses an overcenter mechanism and the carrier mechanism uses an adjustable preload ball and socket for carrier positioning. The handrail clamp uses a stack of disk springs to provide a spring loaded button. This configuration provides consistent clamping force over a range of possible handrail thicknesses. Three load points are incorporated in the clamping mechanism thereby spreading the clamping load onto three separate points on the handrail. A four bar linkage is used to provide for a single actuation lever for all three load points. For additional safety, a secondary lock consisting of a capture plate and push lock keeps the clamp attached to the handrail in the event of main clamp failure. For the carrier positioning mechanism, a ball in a spring loaded socket uses friction to provide locking torque; however. the ball and socket are torque limited so that the ball ran slip under kick loads (125 pounds or greater). A lead screw attached to disk spring stacks is used to provide an adjustable spring force on the socket. A locking knob is attached to the lead screw to allow for hand manipulation of the lead screw.

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

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Zhao Xinze

    2013-01-01

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

  16. 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...

  17. 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

  18. Dynamic clamp: a powerful tool in cardiac electrophysiology.

    Science.gov (United States)

    Wilders, Ronald

    2006-10-15

    Dynamic clamp is a collection of closely related techniques that have been employed in cardiac electrophysiology to provide direct answers to numerous research questions regarding basic cellular mechanisms of action potential formation, action potential transfer and action potential synchronization in health and disease. Building on traditional current clamp, dynamic clamp was initially used to create virtual gap junctions between isolated myocytes. More recent applications include the embedding of a real pacemaking myocyte in a simulated network of atrial or ventricular cells and the insertion of virtual ion channels, either simulated in real time or simultaneously recorded from an expression system, into the membrane of an isolated myocyte. These applications have proven that dynamic clamp, which is characterized by the real-time evaluation and injection of simulated membrane current, is a powerful tool in cardiac electrophysiology. Here, each of the three different experimental configurations used in cardiac electrophysiology is reviewed. Also, directions are given for the implementation of dynamic clamp in the cardiac electrophysiology laboratory. With the growing interest in the application of dynamic clamp in cardiac electrophysiology, it is anticipated that dynamic clamp will also prove to be a powerful tool in basic research on biological pacemakers and in identification of specific ion channels as targets for drug development. PMID:16873403

  19. POLYCYTHEMIA RISK IN NEONATES WITH DELAYED CORD CLAMPING

    OpenAIRE

    I Gusti Agung Ayu Sri Wulandari Pramana; Ketut Putera Kemara; I Wayan Megadhana

    2013-01-01

    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. Polycy...

  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. Insulin Tolerance Test and Hyperinsulinemic-Euglycemic Clamp

    Science.gov (United States)

    Paschos, Georgios K.; FitzGerald, Garret A.

    2016-01-01

    The two tests are used to evaluate in vivo sensitivity to insulin in mouse. The hypoerinsulinemic-euglycemic clamp provides information about the sensitivity to insulin in liver and other metabolically relevant tissues.

  2. Usefulness of Kelly clamp crushing technique during hepatic resection

    OpenAIRE

    Kim, K. H.; Lee, S G

    2008-01-01

    Introduction. Recently, there are various kinds of parenchymal transection methods. The aim of this study is to evaluate the usefulness of the Kelly clamp crushing technique compared to ultrasonic dissector during hepatic resection. Materials and methods. Comparisons between 10 ultrasonic dissector group and 10 Kelly clamp crushing technique group were performed by using nine items (transaction time, right lobe volume, perioperative transfusion, total bilirubin (TB), aspartate aminotransferas...

  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. A NOVEL SINGLE IMPEDANCE NETWORK BASED NEUTRAL POINT CLAMPED SEVEN LEVEL THREE PHASE INVETER WITH REDUCED CLAMPING DIODES FOR REGENERATIVE APPLICATIONS

    OpenAIRE

    T. A. Raghavendiran; C.L.Kuppuswamy

    2012-01-01

    A Multilevel Inverter (MLI) can eliminate the need for the step-up transformer and reduce the harmonics produced by the inverter. This paper presents Neutral Point Clamped (NPC) seven level inverter with less number of clamping diodes which is suitable for regenerative loads such as three phase induction motor with regenerative braking. To reduce the stress across the main switches, diodes are clamped anti-parallel to the main switches. In Earlier configurations, the numbers of clamping diode...

  5. [Pedicular clamping in major hepatectomies: clamping "of principle" or "of necessity"? A comparative study].

    Science.gov (United States)

    Le Treut, Y P; Christophe, M; Banti, J C; Berthet, B; Bricot, R

    1995-02-01

    Fifty-two consecutive patients undergoing major hepatic resection for liver tumor were divided into two groups according to the operative procedure. Group A consisted of 34 patients in whom vascular inflow occlusion was performed "de principle" during parenchymal division and intrahepatic approach of the portal structures; the mean duration of the portal triad clamping was 43 mn (ranged 17 to 70 mn). Group B patients (18 cases) had hilar division of the structures of that portion of the liver due to be removed, prior to parenchymal division was performed without vascular arrest, except in five "de necessitate" cases during 5 to 22 mn. Groups A and B were comparable in terms of patient age or status, of king of liver tumors and extent of resection. Mean operating duration (215 vs 263 mn), volume of intraoperative blood transfusion (557 vs 1019 ml), intensive care (2.5 vs 4.2 days) and total hospital stays (19.6 vs 30.5 days) were significantly reduced in group A. A higher but transient increase of amino-transferase level was the only biochemical consequence of liver ischemia in group A, whereas postoperative disturbance in serum bilirubin, prothrombin time, fibrinogen, and total protein were significantly greater in group B, probably because of the greater volume of blood transfusion in this group. Thus, routine vascular inflow occlusion with transhepatic approach of the portal structures may be an effective and innocuous procedure for major liver resection. PMID:7751341

  6. Improved DNA clamps by stacking to adjacent nucleobases

    DEFF Research Database (Denmark)

    Fatthalla, M.I.; Pedersen, Erik Bjerregaard

    2012-01-01

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

  7. Plasma temperature clamping in filamentation laser induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, Sivanandan S.; Yeak, J.; Phillips, Mark C.

    2015-10-19

    Ultrafast laser filament induced breakdown spectroscopy is a very promising method for remote material detection. We present characteristics of plasmas generated in a metal target by laser filaments in air. Our measurements show that the temperature of the ablation plasma is clamped along the filamentation channel due to intensity clamping in a filament. Nevertheless, significant changes in radiation intensity are noticeable, and this is essentially due to variation in the number density of emitting atoms. The present results also partly explains the reason for the occurrence of atomic plume during fs LIBS in air compared to long-pulse ns LIBS.

  8. 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)

  9. 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.

  10. 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.

  11. Mechanical stability of multidomain proteins and novel mechanical clamps.

    Science.gov (United States)

    Sikora, Mateusz; Cieplak, Marek

    2011-06-01

    We estimate the size of mechanostability for 318 multidomain proteins which are single-chain and contain up to 1021 amino acids. We predict existence of novel types of mechanical clamps in which interdomain contacts play an essential role. Mechanical clamps are structural regions which are the primary source of a protein's resistance to pulling. Among these clamps there is one that opposes tensile stress due to two domains swinging apart. This movement strains and then ruptures the contacts that hold the two domains together. Another clamp also involves tensile stress but it originates from an immobilization of a structural region by a surrounding knot-loop (without involving any disulfide bonds). Still another mechanism involves shear between helical regions belonging to two domains. We also consider the amyloid-prone cystatin C which provides an example of a two-chain 3D domain-swapped protein. We predict that this protein should withstand remarkably large stress, perhaps of order 800 pN, when inducing a shearing strain. The survey is generated through molecular dynamics simulations performed within a structure-based coarse grained model. PMID:21465555

  12. Hyperinsulinemic Euglycemic Clamp for cardiac PET: An Initial Experience

    International Nuclear Information System (INIS)

    Full text: Aim: To study the adequacy of hyperinsulinemic euglycemic clamp to yield technically adequate and clinically meaningful cardiac scans in diabetic patients. 18 F- FDG scans are of suboptimal quality as high level of glucose competes with flurodeoxyglucose for cardiac uptake. Thus to allow quick stabilization of metabolic environment and to get superior quality images, insulin clamp is an accepted technique. Methods: 8 patients (7 males and 1 female) of ages ranging from 43 to 69 years were evaluated in this ongoing study, referred for estimation of myocardial viability post myocardial infarction. All patients were required 6 hours fasting. Initially they were injected with 20 milicurie of Technetium Tetrofosmin and myocardial perfusion imaging done 1 hour later on GE dual head gamma camera. Blood glucose levels were checked. Their blood sugars were in the range of 130mg% - 170mg%. Insulin clamp was applied depending upon the glucose level obtained, according to ASNC guidelines for PET Myocardial Glucose Metabolism and Perfusion Imaging. On stabilization of blood glucose levels, 10 milicurie of 18 F- FDG was injected. Imaging was done 1 hour later on Dedicated 16 slice STE PET CT scanner. There was no incidence of hypoglycemia or any other side effects during the procedure. Entire procedure including tetrofosmin imaging took approximately 4 hours. Results: Good quality images were obtained after the use of insulin clamp. Conclusion: Infusion of insulin and glucose gives stable plasma glucose and serum insulin levels during imaging. The insulin clamp technique makes it possible to adjust and maintain a metabolic steady state during PET study. It does not alter 18F-FDG uptake patterns in different myocardial areas. It permits the use of smaller FDG doses for the patient and gives superior quality images. The technique is safe and should improve both the clinical use and cost effectiveness of FDG-PET imaging for identification of injured but viable myocardium

  13. Vibration control of a flexible clamped-clamped plate based on an improved FULMS algorithm and laser displacement measurement

    Science.gov (United States)

    Xie, Lingbo; Qiu, Zhi-cheng; Zhang, Xian-min

    2016-06-01

    This paper presents a novel active resonant vibration control experiment of a flexible clamped-clamped plate using an improved filtered-U least mean square (FULMS) algorithm and laser displacement measurement. Different from the widely used PZT sensors or acceleration transducers, the vibration of the flexible clamped-clamped plate is measured by a non-contact laser displacement measurement sensor with higher measurement accuracy and without additional load to the plate. The conventional FULMS algorithm often uses fixed step size and needs reference signal related to the external disturbance signal. However, the fixed step size method cannot obtain a fast convergence speed and it will result in a low residual error. Thus, a variable step size method is investigated. In addition, it is difficult to extract reference signal related to the vibration source directly in the practical application. Therefore, it is practically useful that a reference signal is constructed by both the controller parameters and the vibration residual signal. The experimental results demonstrate that the improved FULMS algorithm has better vibration control effect than the proportional derivative (PD) feedback control algorithm and the fixed step-size control algorithm.

  14. 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

  15. Review: The lord of the rings: Structure and mechanism of the sliding clamp loader.

    Science.gov (United States)

    Kelch, Brian A

    2016-08-01

    Sliding clamps are ring-shaped polymerase processivity factors that act as master regulators of cellular replication by coordinating multiple functions on DNA to ensure faithful transmission of genetic and epigenetic information. Dedicated AAA+ ATPase machines called clamp loaders actively place clamps on DNA, thereby governing clamp function by controlling when and where clamps are used. Clamp loaders are also important model systems for understanding the basic principles of AAA+ mechanism and function. After nearly 30 years of study, the ATP-dependent mechanism of opening and loading of clamps is now becoming clear. Here I review the structural and mechanistic aspects of the clamp loading process, as well as comment on questions that will be addressed by future studies. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 532-546, 2016. PMID:26918303

  16. Design of Voltage-clamp-controlled Current-clamp%电压钳控制电流钳的设计

    Institute of Scientific and Technical Information of China (English)

    熊俊; 樊枫; 瞿安连

    2008-01-01

    研究证明,传统膜片钳放大器在电流钳模式下记录到的快速电压信号会存在失真,且造成失真的根本原因是由于膜片钳的探头电路设计.为了克服这些缺陷重新设计了一种探头,新探头电路不仅能像传统的电压跟随器一样测量瞬态电压,而且适用于传统的电压钳工作模式.此外,一种命名为电压钳控制的电流钳技术被应用来改进传统的膜片钳放大器.用可变的低通滤波器来调整电压钳模块的响应速度,从而在实现膜电位钳位的同时准确记录快速电压信号.桥平衡电路用来消除命令电流流过串联电阻时带来的电压误差.而传统膜片钳中的快电容补偿环节则被改进用来补偿电极分布电容和探头放大器输入电容并提高电流钳模式下系统的响应速度.细胞模型实验结果表明,改进后的膜片钳放大器能够满足电生理研究中快速电位变化测量的需要.%Previous research rcvealed that distortion is detected in transient voltage signal recorded with traditional patch clamp amplifier under current clamp mode, which is essentially resulted by electronic design of the headstage of the patch clamp. A new kind of headstage is designed to modify the defect, the circuit of which not only measures the transient potentials as the classical voltage follower does but also is quite suitable for the standard voltage-clamp mode. Furthermore, the technique of voltage-clamp-controlled current-clamp is applied for modifying the conventional patch-clamp amplifier, the variable low-pass filter is added into the circuit to reduce the response speed of voltage-clamp module, thus the transient potentials changes can be measured while membrane potential is kept at a constant value. Bridge balance circuitry is designed to eliminate the voltage drop while the variable current injected into the electrode. And fast capacitance compensation stage of conventional PCA is modified to nentralize the

  17. 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...

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

    DEFF Research Database (Denmark)

    Nami, A.; Zare, F.; Ledwich, G.; Ghosh, A.; Blaabjerg, Frede

    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 of......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...... 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...

  19. 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

  20. Gamma radiation methods for clamp-on multiphase flow metering

    OpenAIRE

    Blaney, S

    2008-01-01

    The development of a cost-effective multiphase flow meter to determine the individual phase flow rates of oil, water and gas was investigated through the exploitation of a single clamp-on gamma densitometer and signal processing techniques. A fast-sampling (250 Hz) gamma densitometer was installed at the top of the 10.5 m high, 108.2 mm internal diameter, stainless steel catenary riser in the Cranfield University multiphase flow test facility. Gamma radiation attenuation data w...

  1. Analysis of Control Strategies for Diode Clamped Multilevel Inverter

    OpenAIRE

    C. R. Balamurugan; S. P. NATARAJAN; R. Revathy

    2013-01-01

    This paper presents the comparison of various Pulse Width Modulation (PWM) strategies for the three phase Diode Clamped Multi Level Inverter (DCMLI). The main contribution of this paper is the proposal of new modulation schemes with Variable Amplitude (VA) and various new schemes adopting the constant switching frequency and also variable switching frequency multicarrier control freedom degree combination concepts are developed and simulated for the chosen three phase DCMLI. The three phase D...

  2. Stretching of proteins in a force-clamp

    OpenAIRE

    Szymczak, Piotr; Cieplak, Marek

    2005-01-01

    Mechanically induced protein unfolding in the force-clamp apparatus is shown, in a coarse-grained model of ubiquitin, to have lognormal statistics above a treshold force and exponential below it. Correspondingly, the mean unfolding time is slowly varying and exponentially decreases as a function of the force. The time dependencies of the end-to-end distances are also distinct. The time sequence of unfolding events weakly depends on force and much of it resembles that for stretching at constan...

  3. The human dynamic clamp as a paradigm for social interaction

    OpenAIRE

    Dumas, Guillaume; de Guzman, Gonzalo C.; Tognoli, Emmanuelle; Kelso, J. A. Scott

    2014-01-01

    The human dynamic clamp (HDC) is proposed as a general paradigm for studies of elementary forms of social behavior in complex biological systems. HDC enables parametric control of real-time bidirectional interaction between humans and empirically grounded theoretical models of coordination dynamics. It thus provides necessary experimental access for laboratory investigations, while preserving the reciprocity and open boundary conditions inherent in daily life social interactions. As proof of ...

  4. 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.

  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. M. tuberculosis Sliding β-Clamp Does Not Interact Directly with the NAD+ -Dependent DNA Ligase

    OpenAIRE

    Vandna Kukshal; Taran Khanam; Deepti Chopra; Nidhi Singh; Sabyasachi Sanyal; Ravishankar Ramachandran

    2012-01-01

    The sliding β-clamp, an important component of the DNA replication and repair machinery, is drawing increasing attention as a therapeutic target. We report the crystal structure of the M. tuberculosis β-clamp (Mtbβ-clamp) to 3.0 Å resolution. The protein crystallized in the space group C222(1) with cell-dimensions a = 72.7, b = 234.9 & c = 125.1 Å respectively. Mtbβ-clamp is a dimer, and exhibits head-to-tail association similar to other bacterial clamps. Each monomer folds into three domains...

  7. Analysis of dynamic properties of boring bars concerning different clamping conditions

    Science.gov (United States)

    Åkesson, Henrik; Smirnova, Tatiana; Håkansson, Lars

    2009-11-01

    Boring bars are frequently used in the manufacturing industry to turn deep cavities in workpieces and are usually associated with vibration problems. This paper focuses on the clamping properties' influence on the dynamic properties of clamped boring bars. A standard clamping housing of the variety commonly used in industry today has been used. Both a standard boring bar and a modified boring bar have been considered. Two methods have been used: Euler-Bernoulli beam modeling and experimental modal analysis. It is demonstrated that the number of clamping screws, the clamping screw diameter sizes, the screw tightening torques, the order the screws are tightened has a significant influence on a clamped boring bars eigenfrequencies and its mode shapes orientation in the cutting speed—cutting depth plane. Also, the damping of the modes is influenced. The results indicate that multi-span Euler-Bernoulli beam models with pinned boundary condition or elastic boundary condition modeling the clamping are preferable as compared to a fixed-free Euler-Bernoulli beam for modeling dynamic properties of a clamped boring bar. It is also demonstrated that a standard clamping housing clamping a boring bar with clamping screws imposes non-linear dynamic boring bar behavior.

  8. Nonlinear vibrations of fluid-filled clamped circular cylindrical shells

    Science.gov (United States)

    Karagiozis, K. N.; Amabili, M.; Païdoussis, M. P.; Misra, A. K.

    2005-12-01

    In this study, the nonlinear vibrations are investigated of circular cylindrical shells, empty or fluid-filled, clamped at both ends and subjected to a radial harmonic force excitation. Two different theoretical models are developed. In the first model, the standard form of the Donnell's nonlinear shallow-shell equations is used; in the second, the equations of motion are derived by a variational approach which permits the inclusion of constraining springs at the shell extremities and taking in-plane inertial terms into account. In both cases, the solution includes both driven and companion modes, thus allowing for a travelling wave in the circumferential direction; they also include axisymmetric modes to capture the nonlinear inward shell contraction and the correct type (softening) nonlinear behaviour observed in experiments. In the first model, the clamped beam eigenfunctions are used to describe the axial variations of the shell deformation, automatically satisfying the boundary conditions, leading to a 7 degree-of-freedom (dof) expansion for the solution. In the second model, rotational springs are used at the ends of the shell, which when large enough reproduce a clamped end; the solution involves a sine series for axial variations of the shell deformation, leading to a 54 dof expansion for the solution. In both cases the modal expansions satisfy the boundary conditions and the circumferential continuity condition exactly. The Galerkin method is used to discretize the equations of motion, and AUTO to integrate the discretized equations numerically. When the shells are fluid-filled, the fluid is assumed to be incompressible and inviscid, and the fluid structure interaction is described by linear potential flow theory. The results from the two theoretical models are compared with existing experimental data, and in all cases good qualitative and quantitative agreement is observed.

  9. Stretching of proteins in a force-clamp

    Energy Technology Data Exchange (ETDEWEB)

    Szymczak, P [Institute of Theoretical Physics, Warsaw University, ulica Hoza 69, 00-681 Warsaw (Poland); Cieplak, Marek [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw (Poland)

    2006-01-11

    Mechanically induced protein unfolding in the force-clamp apparatus is shown, in a coarse-grained model of ubiquitin, to have lognormal statistics above a threshold force and exponential statistics below it. Correspondingly, the mean unfolding time is slowly varying and exponentially decreases as a function of the force. The time dependences of the end-to-end distances are also distinct. The time sequence of unfolding events weakly depends on force and much of it resembles that for stretching at constant speed. A more complicated time dependence arises for integrin. (letter to the editor)

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    This study proposes a five-level Z-source diode-clamped inverter designed with two intermediate Z-source networks connected between the dc input sources and rear-end inverter circuitry. By partially shorting the Z-source networks, new operating states not previously reported for two-level Z...... 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....

  11. A NOVEL SINGLE IMPEDANCE NETWORK BASED NEUTRAL POINT CLAMPED SEVEN LEVEL THREE PHASE INVETER WITH REDUCED CLAMPING DIODES FOR REGENERATIVE APPLICATIONS

    Directory of Open Access Journals (Sweden)

    T. A. Raghavendiran

    2012-09-01

    Full Text Available A Multilevel Inverter (MLI can eliminate the need for the step-up transformer and reduce the harmonics produced by the inverter. This paper presents Neutral Point Clamped (NPC seven level inverter with less number of clamping diodes which is suitable for regenerative loads such as three phase induction motor with regenerative braking. To reduce the stress across the main switches, diodes are clamped anti-parallel to the main switches. In Earlier configurations, the numbers of clamping diodes were increased proportionately with thenumber of levels and the number of impedance network required increases with increase number of levels. Therefore the cost and converter size increases as the number of levels goes high. In this paper a single impedance network based seven level neutral point clamped inverter with reduced number of clamping diodes without deterioration in performance is proposed, the simulation of proposed circuit is carried out using MATLAB/Simulink and the results for the same are presented. The MOSFET internal capacitance and body diodes are used for active clamping which eliminates the need for snubber circuit.

  12. Performance Evaluation of Multicarrier SPWM Strategies for Three Phase Z - source Seven Level Diode Clamped Inverter

    OpenAIRE

    V.Arun#1 , B.Shanthi

    2013-01-01

    This paper presents multicarrier PWM strategies for three phase diode clamped seven level Z-source inverter. Multilevel inverters posses the advantage of reduced harmonics,high power capability and high voltage level. Impedance network in the diode clamped multilevel inverter circuit will perform boost operation. This paper focuses on multicarriersinusoidal pulse width modulation (MCSPWM) strategy for the three phase seven level Z-source diode clamped inverter. Performance parameters of three...

  13. Microchip amplifier for in vitro, in vivo, and automated whole cell patch-clamp recording.

    Science.gov (United States)

    Harrison, Reid R; Kolb, Ilya; Kodandaramaiah, Suhasa B; Chubykin, Alexander A; Yang, Aimei; Bear, Mark F; Boyden, Edward S; Forest, Craig R

    2015-02-15

    Patch clamping is a gold-standard electrophysiology technique that has the temporal resolution and signal-to-noise ratio capable of reporting single ion channel currents, as well as electrical activity of excitable single cells. Despite its usefulness and decades of development, the amplifiers required for patch clamping are expensive and bulky. This has limited the scalability and throughput of patch clamping for single-ion channel and single-cell analyses. In this work, we have developed a custom patch-clamp amplifier microchip that can be fabricated using standard commercial silicon processes capable of performing both voltage- and current-clamp measurements. A key innovation is the use of nonlinear feedback elements in the voltage-clamp amplifier circuit to convert measured currents into logarithmically encoded voltages, thereby eliminating the need for large high-valued resistors, a factor that has limited previous attempts at integration. Benchtop characterization of the chip shows low levels of current noise [1.1 pA root mean square (rms) over 5 kHz] during voltage-clamp measurements and low levels of voltage noise (8.2 μV rms over 10 kHz) during current-clamp measurements. We demonstrate the ability of the chip to perform both current- and voltage-clamp measurement in vitro in HEK293FT cells and cultured neurons. We also demonstrate its ability to perform in vivo recordings as part of a robotic patch-clamping system. The performance of the patch-clamp amplifier microchip compares favorably with much larger commercial instrumentation, enabling benchtop commoditization, miniaturization, and scalable patch-clamp instrumentation. PMID:25429119

  14. 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...... 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....

  15. Cryogenic Clamp-on Ultrasonic Flowmeters using Single Crystal Piezoelectric Transducers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Clamp-on ultrasound cryogenic flowmeters using single crystal piezoelectric transducers are proposed to enable reliable, accurate cryogenic instrumentation needs in...

  16. Self-clamping arc light reflector for welding torch

    Science.gov (United States)

    Gordon, Stephen S.

    1987-07-01

    This invention is directed to a coaxial extending metal mirror reflector attached to the electrode housing or gas cup on a welding torch. An electric welding torch with an internal viewing system for robotic welding is provded with an annular arc light reflector to reflect light from the arc back onto the workpiece. The reflector has a vertical split or gap in its surrounding wall to permit the adjacent wall ends forming the split to be sprung open slightly to permit the reflector to be removed or slipped onto the torch housing or gas cup. The upper opening of the reflector is slightly smaller than the torch housing or gas cup and therefore, when placed on the torch housing or gas cup has that springiness to cause it to clamp tightly on the housing or gas cup. The split or gap also serves to permit the feed of weld wire through to the weld area,

  17. Trans-Z-source Neutral Point Clamped inverter

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  18. Whole-cell Patch-clamp Recordings in Brain Slices.

    Science.gov (United States)

    Segev, Amir; Garcia-Oscos, Francisco; Kourrich, Saïd

    2016-01-01

    Whole-cell patch-clamp recording is an electrophysiological technique that allows the study of the electrical properties of a substantial part of the neuron. In this configuration, the micropipette is in tight contact with the cell membrane, which prevents current leakage and thereby provides more accurate ionic current measurements than the previously used intracellular sharp electrode recording method. Classically, whole-cell recording can be performed on neurons in various types of preparations, including cell culture models, dissociated neurons, neurons in brain slices, and in intact anesthetized or awake animals. In summary, this technique has immensely contributed to the understanding of passive and active biophysical properties of excitable cells. A major advantage of this technique is that it provides information on how specific manipulations (e.g., pharmacological, experimenter-induced plasticity) may alter specific neuronal functions or channels in real-time. Additionally, significant opening of the plasma membrane allows the internal pipette solution to freely diffuse into the cytoplasm, providing means for introducing drugs, e.g., agonists or antagonists of specific intracellular proteins, and manipulating these targets without altering their functions in neighboring cells. This article will focus on whole-cell recording performed on neurons in brain slices, a preparation that has the advantage of recording neurons in relatively well preserved brain circuits, i.e., in a physiologically relevant context. In particular, when combined with appropriate pharmacology, this technique is a powerful tool allowing identification of specific neuroadaptations that occurred following any type of experiences, such as learning, exposure to drugs of abuse, and stress. In summary, whole-cell patch-clamp recordings in brain slices provide means to measure in ex vivo preparation long-lasting changes in neuronal functions that have developed in intact awake animals

  19. The deformation of an elastic rod with a clamp sliding along a smooth and curved profile

    CERN Document Server

    Misseroni, D; Zaccaria, D; Bigoni, D

    2015-01-01

    The design of compliant mechanisms is crucial in several technologies and relies on the availability of solutions for nonlinear structural problems. One of these solutions is given and experimentally validated in the present article for a compliant mechanism moving along a smooth curved profile. In particular, a deformable elastic rod is held by two clamps, one at each end. The first clamp is constrained to slide without friction along a curved profile, while the second clamp moves in a straight line transmitting its motion through the elastic rod to the first clamp. For this system it is shown that the clamp sliding on the profile imposes nontrivial boundary conditions (derived via a variational and an asymptotic approach), which strongly influence buckling and nonlinear structural behaviour. Investigation of this behaviour shows that a compliant mechanism can be designed, which gives an almost neutral response in compression. This behavior could easily be exploited to make a force limiting device. Finally a...

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

    Directory of Open Access Journals (Sweden)

    Zhang-Fu Wang

    2015-01-01

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

  1. Clamp ultrastructure of the basal monogenean Chimaericola leptogaster (Leuckart, 1830) (Polyopisthocotylea: Chimaericolidae).

    Science.gov (United States)

    Poddubnaya, Larisa G; Hemmingsen, Willy; Gibson, David I

    2014-11-01

    The ultrastructure of the haptoral clamps of the chimaericolid monogenean Chimaericola leptogaster, a basal polyopisthocotylean from the gills of a holocephalan fish, is described. These clamps are characterized by the presence of two muscle blocks interrupted mid-anteriorly and mid-posteriorly and different kinds of hard structures: a single median and paired lateral sclerites embedded in the clamp wall; six spine-like structures directed towards the clamp lumen; and electron dense surface structures along the internal surface of the anterior clamp lips and along the luminal surface of the tegument of the clamp lumen. The lateral sclerites are situated deep within muscular tissue and are closely bounded by radial myofibrils, possessing a uniform electron dense matrix within which are hollow areas of different sizes. The median sclerite occupies an area between the clamp wall myofibrils and the luminal epithelium, is surrounded by a basement lamina and is composed of a heterogeneous matrix comprising two different morphological layers related to variations in the type and concentration of fibrils. Four of the spine-like structures are extensions of the margins of the two spindle-like muscle blocks in the clamps, i.e. the two anterior and two posterior structures, and the two others are situated at the lateral constrictions of the left and right muscle blocks. The electron dense surface structures are derivations of the clamp tegument or, to be more precise, its outer, densely fibrous region. These results are discussed in relation to the evidence that the haptoral clamps of C. leptogaster are apparently ancient origin. PMID:25112214

  2. Voltage clamping single cells in intact malpighian tubules of mosquitoes.

    Science.gov (United States)

    Masia, R; Aneshansley, D; Nagel, W; Nachman, R J; Beyenbach, K W

    2000-10-01

    Principal cells of the Malpighian tubule of the yellow fever mosquito were studied with the methods of two-electrode voltage clamp (TEVC). Intracellular voltage (V(pc)) was -86.7 mV, and input resistance (R(pc)) was 388.5 kOmega (n = 49 cells). In six cells, Ba(2+) (15 mM) had negligible effects on V(pc), but it increased R(pc) from 325.3 to 684.5 kOmega (P usefulness of TEVC methods in single principal cells of the intact Malpighian tubule. Dinitrophenol (0.1 mM) reversibly depolarized V(pc) from -94.3 to -10.7 mV (P < 0.001) and reversibly increased R(pc) from 412 to 2,879 kOmega (P < 0.001), effects that were duplicated by cyanide (0.3 mM). Significant effects of metabolic inhibition on voltage and resistance suggest a role of ATP in electrogenesis and the maintenance of conductive transport pathways. PMID:10997925

  3. Analysis of Control Strategies for Diode Clamped Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    C. R. Balamurugan

    2013-05-01

    Full Text Available This paper presents the comparison of various Pulse Width Modulation (PWM strategies for the three phase Diode Clamped Multi Level Inverter (DCMLI. The main contribution of this paper is the proposal of new modulation schemes with Variable Amplitude (VA and various new schemes adopting the constant switching frequency and also variable switching frequency multicarrier control freedom degree combination concepts are developed and simulated for the chosen three phase DCMLI. The three phase DCMLI, is controlled in this paper with Sinusoidal PWM (SPWM reference along with triangular carriers and analysis is made among both without carrier overlapping and with Carrier Overlapping (CO techniques to choose the better strategy by performing simulation using MATLAB-SIMULINK. The variation of Total Harmonic Distortion (THD and fundamental RMS output voltage is observed for various modulation indices. It is observed that among the various equal amplitude PWM strategies, COPWM-C provides less THD and higher RMS voltage. It is recognized that among the various variable amplitude PWM strategies, VACOPWM-C provides less THD and VACOPWM-B provides higher RMS voltage. By comparing the equal amplitude PWM strategies with the variable amplitude PWM strategies it is inferred that VACOPWM-C provides less THD and VACOPWM-B provides higher RMS voltage. It is also inferred that carrier overlapping techniques provides better results compared to the without carrier overlapping techniques.

  4. Position clamping in a holographic counterpropagating optical trap.

    Science.gov (United States)

    Bowman, Richard; Jesacher, Alexander; Thalhammer, Gregor; Gibson, Graham; Ritsch-Marte, Monika; Padgett, Miles

    2011-05-01

    Optical traps consisting of two counterpropagating, divergent beams of light allow relatively high forces to be exerted along the optical axis by turning off one beam, however the axial stiffness of the trap is generally low due to the lower numerical apertures typically used. Using a high speed spatial light modulator and CMOS camera, we demonstrate 3D servocontrol of a trapped particle, increasing the stiffness from 0.004 to 1.5 μN m(-1). This is achieved in the "macro-tweezers" geometry [Thalhammer, J. Opt. 13, 044024 (2011); Pitzek, Opt. Express 17, 19414 (2009)], which has a much larger field of view and working distance than single-beam tweezers due to its lower numerical aperture requirements. Using a 10×, 0.2 NA objective, active feedback produces a trap with similar effective stiffness to a conventional single-beam gradient trap, of order 1 μN m(-1) in 3D. Our control loop has a round-trip latency of 10 ms, leading to a resonance at 20 Hz. This is sufficient bandwidth to reduce the position fluctuations of a 10 μm bead due to Brownian motion by two orders of magnitude. This approach can be trivially extended to multiple particles, and we show three simultaneously position-clamped beads. PMID:21643247

  5. Concentrations of plastic strains in the clamping region of cylindrical shells under excessive loading

    International Nuclear Information System (INIS)

    Different clamping conditions and variations of the material behaviour are considered. Especially the plastic strain concentrations at the shell clamping are determined. The analyses have been carried out with a finite-element code. Standard stress analysis procedures like the ASME-code are critically assessed. The results show that only minor plastic strain concentrations have to be expected for a rigidly clamped shell loaded by internal pressure. The work hardening characteristic of the material has little influence on these strain concentrations. On the other hand considerable plastic strain concentrations have to be expected at a flange type clamping loaded by axial stresses in the shell. These concentrations depend on the work hardening characteristic of the material. Comparison of these analyses with standard stress analysis procedures shows that these procedures are conservative, provided the classification of the different types of stresses has been done in a correct way which, however, may be difficult for some problems. For instance, for the rigidly clamped shell bending stresses can be classified as secondary stresses, but for a flange type clamping bending stresses must be treated as primary stresses with lower limits. With these results the structural integrity of the core barrel clamping of a PWR under blowdown loading has been assessed. Even in case of a sudden and complete pipe break the structure is able to withstand blowdown loading. (orig./HP)

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    In this paper, a FEM (finite element method) based mechanical model for PP (press-pack) IGBTs (insulated gate bipolar transistors) is presented, which can be used to calculate the clamping force distribution among chips under various clamping conditions. The clamping force is an important parameter...

  7. Voltage clamp of the cardiac sodium current at 37 degrees C in physiologic solutions.

    OpenAIRE

    Murray, K T; Anno, T.; Bennett, P B; Hondeghem, L M

    1990-01-01

    The cardiac sodium current was studied in guinea pig ventricular myocytes using the cell-attached patch voltage clamp at 37 degrees C in the presence of 145 mM external sodium concentration. When using large patch pipettes (access resistance, 1-2 M omega), the capacity current transient duration was typically 70 microseconds for voltage clamp steps up to 150 mV. At 37 degrees C the maximum inward sodium current peaked in approximately 200 microseconds after the onset of a clamp step and at th...

  8. Nuclear EMP: voltage clamping levels for several TransZorb transient suppression devices

    International Nuclear Information System (INIS)

    Voltage clamping levels for the 1N5629A, 1N5545A, 1N5654A, and 1N5664A TransZorb/sup T.M./ silicon transient-suppression devices in a DO-13 package are presented as data in photographs of test waveforms. A graph is compiled which illustrates the clamping voltage at a time point of 80 nsec for each of the devices. The duration of the test pulse was 250 nsec with a slope of 4 kV per nsec for the rise portion. Clamping levels are nearly constant for test current amplitudes of up to 120 A

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

    Directory of Open Access Journals (Sweden)

    Goedken Eric R

    2010-01-01

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

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

    International Nuclear Information System (INIS)

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

  11. BER improvement using optical gain clamped amplifier for burst transmission and critical cases studies

    OpenAIRE

    Zannin, Marcelo; Ennser, Karin; Taccheo, Stefano; Careglio, Davide; Solé Pareta, Josep; Aracil Rico, Javier

    2009-01-01

    This paper demonstrates significant BER improvement in burst traffic transmission using optical-gain clamped amplifiers. Critical chaotic cases are identified for peculiar burst sequences and their impact in transmission is assessed.

  12. Effective amplification of real WDM burst traffic using optical gain clamping

    OpenAIRE

    Zannin, Marcelo; Taccheo, Stefano; Ennser, Karin; Careglio, Davide; Solé Pareta, Josep

    2008-01-01

    Experimental studies of real optical burst traffic in WDM systems are performed with optical gain clamping for stabilizing the EDFA amplification. Impairments of power variation due to burst are shown to be negligible.

  13. 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.

  14. A novel voltage clamp technique for mapping ionic currents from cultured skeletal myotubes.

    OpenAIRE

    Anson, B D; Roberts, W M

    1998-01-01

    The biophysical properties and cellular distribution of ion channels largely determine the input/output relationships of electrically excitable cells. A variety of patch pipette voltage clamp techniques are available to characterize ionic currents. However, when used by themselves, such techniques are not well suited to the task of mapping low-density channel distributions. We describe here a new voltage clamp method (the whole cell loose patch (WCLP) method) that combines whole-cell recordin...

  15. Delayed umbilical cord clamping after childbirth: potential benefits to baby's health

    Directory of Open Access Journals (Sweden)

    Uwins C

    2014-11-01

    Full Text Available Christina Uwins,1 David JR Hutchon2 1Department of Obstetrics and Gynaecology, Croydon University Hospital, Croydon, 2Department of Obstetrics, Darlington Memorial Hospital, Darlington, UKAbstract: Early cord clamping was initially introduced as part of the package of care known as “active management of the third stage”, which was implemented to reduce postpartum hemorrhage. It has now been shown to provide no benefit to the mother and to result in harm to the neonate. The clinical trial evidence relating to delayed cord clamping compared to immediate cord clamping is presented and the physiological rationale for delayed cord clamping is discussed in this paper. Most organizations (eg World Health Organization (WHO, Royal College of Obstetricians and Gynaecologists (RCOG, Resuscitation Council (UK,The International Federation of Gynecology and Obstetrics (FIGO, International Confederation of Midwives, International Liaison Committee on Resuscitation (ILCOR and the European Resuscitation Council now advise a delay of 1–3 minutes before clamping the cord in term and preterm infants, and clinicians need to be aware of this change. Healthy neonates benefit from a more physiological and gentle transition from placental to pulmonary respiration, and we explain why this benefit should be provided to all neonates until there is any evidence to the contrary. The harm of early cord clamping is not limited to anemia and iron deficiency, and evidence for a wide range of possible harms of early cord clamping is presented. The need for resuscitation is one of the most common concerns, and ways of overcoming these concerns are described.Keywords: transition, cord clamping, hypovolemia, intraventricular hemorrhage

  16. Development of a Reusable, Low-Shock Clamp Band Separation System for Small Spacecraft Release Applications

    OpenAIRE

    Dowen, David; Christiansen, Scott; Peffer, Andrew

    2001-01-01

    In small spacecraft, the proximity of sensitive components to release systems has led to the need for lowshock spacecraft release systems. Marmon band systems are often desirable for their flight history, structural capability, and reliability. Until recently, only pyrotechnically released clamp bands were readily available. The clamp band system described in ths paper reduces shock in two ways: it eliminates shock typically associated with pyrotechnic release devices as well as utilizing a r...

  17. 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.

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

    OpenAIRE

    V. Ranjith Kumar

    2013-01-01

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

  19. Active Clamped ZVS Forward Converter With Soft-Switched Synchronous Rectifier

    OpenAIRE

    AÇIK, Adnan; ÇADIRCI, Işık

    2002-01-01

    This paper presents the analysis, design and implementation of an active-clamped, ZVS forward converter equipped with a soft-switched synchronous rectifier (ACFC-SR) proposed for high-efficiency, low output voltage dc-dc converter applications. The converter efficiency is maximized due to the soft-switching of the main, active clamp, synchronous rectifier and freewheeling MOSFET switches. The operating principles of the ACFC-SR are analyzed in detail and the converter performance is ...

  20. Deformation and perforation of clamped work-hardening plates struck transversely by blunt missiles

    International Nuclear Information System (INIS)

    A simple theory is given in this paper for the behaviour of clamped circular work-hardening plates struck transversely by flat-ended projectiles which travel at low velocities. By closely following the previous studies, force-displacement relationships are obtained and used to predict the deformation and perforation of the plates. It is shown that the theoretical predictions agree well with the experimental results on fully clamped steel plates when strain rate effects are taken into account. (orig.)

  1. Single-stage active clamp power factor correction AC/DC converter

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A simple single-stage AC/DC converter circuit with active clamp is presented. The operation theory and state are analyzed. The experimental results show that the voltage across main switch can be clamped to a certain value, and zero voltage switching (ZVS) can be achieved. The voltage stress and switching loss are both decreased. In range of the whole load, power factors can be always more than 97%, and the highest efficiency can reach 88%.

  2. 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

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

    International Nuclear Information System (INIS)

    In this paper the design, modeling and fabrication of a precision MEMS-based clamp with a relatively large clamping force are presented. The purpose of the clamp is to mechanically fix a six-degree-of-freedom (DOF) MEMS-based sample manipulator (Brouwer et al J. Int. Soc. Precis. Eng. Nanotechnol. submitted) once the sample has been positioned in all DOFs. The clamping force is generated by a rotational electrostatic comb-drive actuator and can be latched passively by a parallel plate type electrostatically driven locking device. The clamp design is based on the principles of exact constraint design, resulting in a high actuation compliance (flexibility) combined with a high suspension stiffness. Therefore, a relatively large blocking force of 1.4 mN in relation to the used area of 1.8 mm2 is obtained. The fabrication is based on silicon bulk micromachining technology and combines a high-aspect-ratio deep reactive ion etching (DRIE), conformal deposition of low-pressure chemical vapor deposition (LPCVD) silicon nitride and an anisotropic potassium hydroxide (KOH) backside etching technology. Special attention is given to void reduction of SixNy trench isolation and reduction of heating phenomena during front-side release etching. Guidelines are given for the applied process. Measurements showed that the clamp was able to fix, hold and release a test actuator. The dynamic behavior was in good agreement with the modal analysis

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

    Directory of Open Access Journals (Sweden)

    Timm eDanker

    2014-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-17

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

  6. Peptide- and proton-driven allosteric clamps catalyze anthrax toxin translocation across membranes.

    Science.gov (United States)

    Das, Debasis; Krantz, Bryan A

    2016-08-23

    Anthrax toxin is an intracellularly acting toxin in which sufficient information is available regarding the structure of its transmembrane channel, allowing for detailed investigation of models of translocation. Anthrax toxin, comprising three proteins-protective antigen (PA), lethal factor (LF), and edema factor-translocates large proteins across membranes. Here we show that the PA translocase channel has a transport function in which its catalytic active sites operate allosterically. We find that the phenylalanine clamp (ϕ-clamp), the known conductance bottleneck in the PA translocase, gates as either a more closed state or a more dilated state. Thermodynamically, the two channel states have >300-fold different binding affinities for an LF-derived peptide. The change in clamp thermodynamics requires distant α-clamp and ϕ-clamp sites. Clamp allostery and translocation are more optimal for LF peptides with uniform stereochemistry, where the least allosteric and least efficiently translocated peptide had a mixed stereochemistry. Overall, the kinetic results are in less agreement with an extended-chain Brownian ratchet model but, instead, are more consistent with an allosteric helix-compression model that is dependent also on substrate peptide coil-to-helix/helix-to-coil cooperativity. PMID:27506790

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    Vandna Kukshal

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

  9. Yielding of the clamped-wire system in the Ilizarov external fixator.

    Science.gov (United States)

    Watson, M A; Matthias, K J; Maffulli, N; Hukins, D W L

    2003-01-01

    This study demonstrates that the clamped-wire system used to suspend bones within an Ilizarov external fixator yields when the perpendicular load exceeds 50 N per wire. Cyclic loading was applied to tensioned wires clamped within an Ilizarov ring component, with steadily increasing load amplitude. Wires were tested at four initial tension settings. The amount of energy lost within the clamped-wire system per load cycle was calculated for every test. The results showed that there was a consistent trend to increasing non-recoverable energy loss per load cycle when peak loads exceed 50 N for all initial tension settings. A finite element (FE) model replicating the experimental conditions was performed to investigate the levels of stress within the loaded wires. The FE model analyses showed that high stresses were generated in the wires close to the clamping sites, and that the stress levels could reasonably be expected to exceed the material yield stress when loaded to about 55 N, for all initial tension settings. The results show that material yield, accompanied by some wire slippage through the clamps, is responsible for system yield, in agreement with previous studies. Although the initial wire tension has an appreciable effect on the wire stiffness, it did not affect the elastic load range of the clamped-wire system. To prevent yield of the clamped-wire system in practice, the fixator should be assembled with sufficient wires to ensure that the load transmitted to each wire by the patient does not exceed 50 N. PMID:14558649

  10. Intermittent selective clamping improves rat liver regeneration by attenuating oxidative and endoplasmic reticulum stress.

    Science.gov (United States)

    Ben Mosbah, I; Duval, H; Mbatchi, S-F; Ribault, C; Grandadam, S; Pajaud, J; Morel, F; Boudjema, K; Compagnon, P; Corlu, A

    2014-01-01

    Intermittent clamping of the portal trial is an effective method to avoid excessive blood loss during hepatic resection, but this procedure may cause ischemic damage to liver. Intermittent selective clamping of the lobes to be resected may represent a good alternative as it exposes the remnant liver only to the reperfusion stress. We compared the effect of intermittent total or selective clamping on hepatocellular injury and liver regeneration. Entire hepatic lobes or only lobes to be resected were subjected twice to 10 min of ischemia followed by 5 min of reperfusion before hepatectomy. We provided evidence that the effect of intermittent clamping can be damaging or beneficial depending to its mode of application. Although transaminase levels were similar in all groups, intermittent total clamping impaired liver regeneration and increased apoptosis. In contrast, intermittent selective clamping improved liver protein secretion and hepatocyte proliferation when compared with standard hepatectomy. This beneficial effect was linked to better adenosine-5'-triphosphate (ATP) recovery, nitric oxide production, antioxidant activities and endoplasmic reticulum adaptation leading to limit mitochondrial damage and apoptosis. Interestingly, transient and early chaperone inductions resulted in a controlled activation of the unfolded protein response concomitantly to endothelial nitric oxide synthase, extracellular signal-regulated kinase-1/2 (ERK1/2) and p38 MAPK activation that favors liver regeneration. Endoplasmic reticulum stress is a central target through which intermittent selective clamping exerts its cytoprotective effect and improves liver regeneration. This procedure could be applied as a powerful protective modality in the field of living donor liver transplantation and liver surgery. PMID:24603335

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

    Directory of Open Access Journals (Sweden)

    Gilberto José Cação Pereira

    2008-07-01

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

  12. A bacterial toxin inhibits DNA replication elongation through a direct interaction with the β sliding clamp.

    Science.gov (United States)

    Aakre, Christopher D; Phung, Tuyen N; Huang, David; Laub, Michael T

    2013-12-12

    Toxin-antitoxin (TA) systems are ubiquitous on bacterial chromosomes, yet the mechanisms regulating their activity and the molecular targets of toxins remain incompletely defined. Here, we identify SocAB, an atypical TA system in Caulobacter crescentus. Unlike canonical TA systems, the toxin SocB is unstable and constitutively degraded by the protease ClpXP; this degradation requires the antitoxin, SocA, as a proteolytic adaptor. We find that the toxin, SocB, blocks replication elongation through an interaction with the sliding clamp, driving replication fork collapse. Mutations that suppress SocB toxicity map to either the hydrophobic cleft on the clamp that binds DNA polymerase III or a clamp-binding motif in SocB. Our findings suggest that SocB disrupts replication by outcompeting other clamp-binding proteins. Collectively, our results expand the diversity of mechanisms employed by TA systems to regulate toxin activity and inhibit bacterial growth, and they suggest that inhibiting clamp function may be a generalizable antibacterial strategy. PMID:24239291

  13. Dynamics of beta and proliferating cell nuclear antigen sliding clamps in traversing DNA secondary structure.

    Science.gov (United States)

    Yao, N; Hurwitz, J; O'Donnell, M

    2000-01-14

    Chromosomal replicases of cellular organisms utilize a ring shaped protein that encircles DNA as a mobile tether for high processivity in DNA synthesis. These "sliding clamps" have sufficiently large linear diameters to encircle duplex DNA and are perhaps even large enough to slide over certain DNA secondary structural elements. This report examines the Escherichia coli beta and human proliferating cell nuclear antigen clamps for their ability to slide over various DNA secondary structures. The results show that these clamps are capable of traversing a 13-nucleotide ssDNA loop, a 4-base pair stem-loop, a 4-nucleotide 5' tail, and a 15-mer bubble within the duplex. However, upon increasing the size of these structures (20-nucleotide loop, 12-base pair stem-loop, 28-nucleotide 5' tail, and 20-nucleotide bubble) the sliding motion of the beta and proliferating cell nuclear antigen over these elements is halted. Studies of the E. coli replicase, DNA polymerase III holoenzyme, in chain elongation with the beta clamp demonstrate that upon encounter with an oligonucleotide annealed in its path, it traverses the duplex and resumes synthesis on the 3' terminus of the oligonucleotide. This sliding and resumption of synthesis occurs even when the oligonucleotide contains a secondary structure element, provided the beta clamp can traverse the structure. However, upon encounter with a downstream oligonucleotide containing a large internal secondary structure, the holoenzyme clears the obstacle by strand displacing the oligonucleotide from the template. Implications of these protein dynamics to DNA transactions are discussed. PMID:10625694

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

    Directory of Open Access Journals (Sweden)

    Yi Zhou

    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.

  15. 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.

  16. Nonlinear Bending Stiffness of Plates Clamped by Bolted Joints under Bending Moment

    Science.gov (United States)

    Naruse, Tomohiro; Shibutani, Yoji

    Equivalent stiffness of plates clamped by bolted joints for designing should be evaluated according to not only the strength of bolted joints but also the deformation and vibration characteristics of the structures. When the applied external axial load or the bending moment is sufficiently small, the contact surfaces of the bolted joint are stuck together, and thus both the bolt and the clamped plates deform linearly. Although the sophisticated VDI 2230 code gives the appropriate stiffness of clamped plates for the infinitesimal deformation, the stiffness may vary nonlinearly with increasing the loading because of changing the contact state. Therefore, the present paper focuses on the nonlinear behaviour of the bending stiffness of clamped plates by using Finite Element (FE) analyses, taking the contact condition on bearing surfaces and between the plates into account. The FE models of the plates with thicknesses of 3.2, 4.5, 6.0 and 9.0 mm tightened with M8, 10, 12 and 16 bolts were constructed. The relation between bending moment and bending compliance of clamped plates is found to be categorized into three regions, namely, (i) constant compliance with fully stuck contact surfaces, (ii) transition showing the nonlinear compliance, and (iii) constant compliance with one-side contact surfaces. The mechanical models for these three regions are proposed and compared with FEM solutions. The prediction on the bounds of three regions is in a fairly good agreement except the case with smaller bolts and thicker plates.

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

    DEFF Research Database (Denmark)

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

    2003-01-01

    "Tail-clamp" PNAs composed of a short (hexamer) homopyrimidine triplex forming domain and a (decamer) mixed sequence duplex forming extension have been designed. Tail-clamp PNAs display significantly increased binding to single-stranded DNA compared with PNAs lacking a duplex-forming extension as...... determined by T-m measurements. Binding to double-stranded (ds) DNA occurred by combined triplex and duplex invasion as analyzed by permanganate probing. Furthermore, C-50 measurements revealed that tail-clamp PNAs consistently bound the dsDNA target more efficiently, and kinetics experiments revealed that...... this was due to a dramatically reduced dissociation rate of such complexes. Increasing the PNA net charge also increased binding efficiency, but unexpectedly, this increase was much more pronounced for tailless-clamp PNAs than for tail-clamp PNAs. Finally, shortening the tail-clamp PNA triplex invasion...

  18. Delayed cord clamping in red blood cell alloimmunization: safe, effective, and free?

    Science.gov (United States)

    McAdams, Ryan M

    2016-04-01

    Hemolytic disease of the newborn (HDN), an alloimmune disorder due to maternal and fetal blood type incompatibility, is associated with fetal and neonatal complications related to red blood cell (RBC) hemolysis. After delivery, without placental clearance, neonatal hyperbilirubinemia may develop from ongoing maternal antibody-mediated RBC hemolysis. In cases refractory to intensive phototherapy treatment, exchange transfusions (ET) may be performed to prevent central nervous system damage by reducing circulating bilirubin levels and to replace antibody-coated red blood cells with antigen-negative RBCs. The risks and costs of treating HDN are significant, but appear to be decreased by delayed umbilical cord clamping at birth, a strategy that promotes placental transfusion to the newborn. Compared to immediate cord clamping (ICC), safe and beneficial short-term outcomes have been demonstrated in preterm and term neonates receiving delayed cord clamping (DCC), a practice that may potentially be effective in cases RBC alloimmunization. PMID:27186530

  19. Significance of Shrinkage Induced Clamping Pressure in Fiber-Matrix Bonding in Cementitious Composite Materials

    DEFF Research Database (Denmark)

    Stang, Henrik

    1996-01-01

    The present paper accesses the significance of shrinkage inducedclamping pressure in fiber/matrix bonding mechanisms incementitious composite materials. The paper contains a description of an experimental setup whichallows mbox{measurement} of the clamping pressure which develops on anelastic...... inhomogeneity embedded in a matrix consisting of acementitious material undergoing shrinkage during hydration(autogenous shrinkage). Furthermore, the paperpresents the analysis necessary to perform an interpretation of the experimental results and which allows for thedetermination of the clamping pressure...... used in high performance cementitious composite materials.Assuming a Coulomb type of friction on the fiber/matrix interface andusing typical values for the frictional coefficient it is shownthat the shrinkage induced clamping pressure could be one of the mostimportant factors determining the frictional...

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

    Directory of Open Access Journals (Sweden)

    Christopher Lawton

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-09-01

    There is currently no consensus among clinicians and scientists over the appropriate or optimal timing for umbilical cord clamping. However, many clinical studies have suggested that delayed cord clamping is associated with various neonatal benefits including increased blood volume, reduced need for blood transfusion, increased cerebral oxygenation in pre-term infants, and decreased frequency of iron deficiency anemia in term infants. Human umbilical cord blood contains significant amounts of stem and progenitor cells and is currently used in the treatment of several life-threatening diseases. We propose that delayed cord clamping be encouraged as it enhances blood flow from the placenta to the neonate, which is accompanied by an increase supply of valuable stem and progenitor cells, as well as may improve blood oxygenation and increase blood volume, altogether reducing the infant's susceptibility to both neonatal and age-related diseases. PMID:26604879

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

    Institute of Scientific and Technical Information of China (English)

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

    2015-01-01

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

  3. Development of planar patch clamp technology and its application in the analysis of cellular electrophysiology

    Institute of Scientific and Technical Information of China (English)

    Peihua Chen; Wei Zhang; Jun Zhou; Ping Wang; Lidan Xiao; Mo Yang

    2009-01-01

    A patch clamp chip, as a novel cell-based chip for electrophysiological recordings, has many prominent advantages such as high res-olution, accuracy, high throughput and automation. It can be used to perform multivariate and real-time measurements of cell networks in situ. Therefore, this technology will dramatically promote the research on ionic channels, neuronal networks and the application of this technology in drug screening. This paper reviews the development of planar patch clamp technology and its applications in detail. The latest progress in the research of taste cells electrophysiology and taste transduction is also presented. Finally, this paper analyzes the methodology of neural chips. Based on the current research of our laboratory, the prospective applications of a patch clamp chip in the research of taste sensation and transduction mechanisms at molecular and cellular levels are discussed.

  4. Delayed cord clamping for prevention of iron deficiency anemia in term infants

    Directory of Open Access Journals (Sweden)

    Olga Rasiyanti Siregar

    2012-07-01

    Full Text Available Background Iron deficiency anemia (IDA during infancy and childhood is a concern due to its potentially detrimental effects on development, some of which may be irreversible even after iron treatment. Delayed cord clamping may prevent IDA by increasing an infant’s iron reserve at birth. Objective We aimed to evaluate the effect of delayed umbilical cord clamping at birth on the iron status in newborns at age 24 hours of life. Methods This randomized, single-blind study was conducted from March to May 2009, at two general hospitals in Medan, North Sumatera Province. Eligible newborn infants were randomly assigned to one of two groups: early cord clamping (ECC performed 15 seconds after delivery or delayed cord clamping (DCC performed 2 minutes after delivery. Infants were placed on their mothers’ abdomens before the umbilical cords were clamped. Hematologic status was determined from umbilical cord blood. Results Sixty-three subjects were included in our study, consisting of 31 infants in the ECC group and 32 infants in the DCC group. We found that mean neonatal hemoglobin level was higher in the DCC group than in the ECC group (18.4 g% and 16.2 g%, respectively, P=0.0001. Also, mean ferritin level was higher in the DCC group than in the ECC group (556 mg/dL and 329 mg/dL, respectively, P=0.015. Other hematological status indicators, including mean hematocrit and mean corpuscular volume (MCV level, were also higher in the DCC group. However, mean red blood cell levels were not significantly different between the two groups. Nor was there a significant difference in mean bilirubin level between the DCC and ECC groups. Conclusion Delayed cord clamping may improve iron status and prevent IDA in term infants.

  5. Role of the α Clamp in the Protein Translocation Mechanism of Anthrax Toxin.

    Science.gov (United States)

    Brown, Michael J; Thoren, Katie L; Krantz, Bryan A

    2015-10-01

    Membrane-embedded molecular machines are utilized to move water-soluble proteins across these barriers. Anthrax toxin forms one such machine through the self-assembly of its three component proteins--protective antigen (PA), lethal factor, and edema factor. Upon endocytosis into host cells, acidification of the endosome induces PA to form a membrane-inserted channel, which unfolds lethal factor and edema factor and translocates them into the host cytosol. Translocation is driven by the proton motive force, composed of the chemical potential, the proton gradient (ΔpH), and the membrane potential (Δψ). A crystal structure of the lethal toxin core complex revealed an "α clamp" structure that binds to substrate helices nonspecifically. Here, we test the hypothesis that, through the recognition of unfolding helical structure, the α clamp can accelerate the rate of translocation. We produced a synthetic PA mutant in which an α helix was crosslinked into the α clamp to block its function. This synthetic construct impairs translocation by raising a yet uncharacterized translocation barrier shown to be much less force dependent than the known unfolding barrier. We also report that the α clamp more stably binds substrates that can form helices than those, such as polyproline, that cannot. Hence, the α clamp recognizes substrates by a general shape-complementarity mechanism. Substrates that are incapable of forming compact secondary structure (due to the introduction of a polyproline track) are severely deficient for translocation. Therefore, the α clamp and its recognition of helical structure in the translocating substrate play key roles in the molecular mechanism of protein translocation. PMID:26344833

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

    International Nuclear Information System (INIS)

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

  7. Cracking associated with micrometeoroid impact craters in anodized aluminum alloy clamps on LDEF

    Science.gov (United States)

    Murr, Lawrence E.; Niou, Chorng S.; Quinones, Stella; Murr, Kyle S.

    1992-01-01

    The Long Duration Exposure Facility (LDEF) is a reusable hollow-cylindrical satellite sustaining a total of 57 different experiments. The 130 sq m of spacecraft surface area included anodized 6061-T6 Al alloy bay frames and clamps for holding experiment trays in the bay areas. Attention is presently given to the micrometeoroid impact crater features observed on two tray clamps recovered from the LDEF leading-edge locations. It is found that even very subtle surface modifications in structural alloy anodizing can influence micrometeoroid impact crater cracking, notable radial cracking due to the ejecta-rim of the impact craters.

  8. High pressure clamp for electrical measurements up to 8 GPa and temperature down to 77 K

    Science.gov (United States)

    Bandyopadhyay, A. K.; Nalini, A. V.; Gopal, E. S. R.; Subramanyam, S. V.

    1980-01-01

    A compact clamp-type high pressure cell for carrying out electrical conductivity measurements on small solid samples of size 1 mm or less at pressures upto 8 GPa (i.e., 80 kbar) and for use down to 77 K has been designed and fabricated. The pressure generated in the sample region has been calibrated at room temperature against the polymorphic phase transitions of Bismuth and Ytterbium. The pressure relaxation of the clamp at low temperatures has been estimated by monitoring the electrical conductivity behavior of lead.

  9. 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.

  10. Two-Dimensional Fiber Positioning and Clamping Device for Product-Internal Microassembly

    NARCIS (Netherlands)

    Henneken, V.A.; Sassen, W.P.; Van der Vlist, W.; Wien, W.H.A.; Tichem, M.; Sarro, P.M.

    2008-01-01

    In this paper, we present a microelectromechanical systems-based two-degrees-of-freedom positioning device combined with a clamping structure for positioning and constraining an optical fiber. The fiber position can be controlled in the two directions perpendicular to the fiber axis using two specif

  11. ELECTROCARDIOGRAPHIC RESPONSES OF RAT FETUSES WITH CLAMPED OR INTACT UMBILICAL CORDS TO ACUTE MATERNAL UTERINE ISCHEMIA

    Science.gov (United States)

    Uterine ischemia results in severe cardiac disturbances in the fetus. It has been postulated that these effects are due to interaction with the ischemic uterus or placenta and not due to hypoxia or build up of metabolites in the fetus. The fetal cardiac responses to uterine clamp...

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

    Directory of Open Access Journals (Sweden)

    Avner Wallach

    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.

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

    DEFF Research Database (Denmark)

    Moller, N.K.; Weber, T.

    2008-01-01

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

  14. Experimental and numerical analysis of clamped joints in front motorbike suspensions

    Directory of Open Access Journals (Sweden)

    Vincenzi N.

    2010-06-01

    Full Text Available Clamped joints are shaft-hub connections used, as an instance, in front motorbike suspensions to lock the steering plates with the legs and the legs with the wheel pin, by means of one or two bolts. The preloading force, produced during the tightening process, should be evaluated accurately, since it must lock safely the shaft, without overcoming the yielding point of the hub. Firstly, friction coefficients have been evaluated on “ad-hoc designed” specimens, by applying the Design of Experiment approach: the applied tightening torque has been precisely related to the imposed preloading force. Then, the tensile state of clamps have been evaluated both via FEM and by leveraging some design formulae proposed by the Authors as function of the preloading force and of the clamp geometry. Finally, the results have been compared to those given by some strain gauges applied on the tested clamps: the discrepancies between numerical analyses, the design formulae and the experimental results remains under a threshold of 10%.

  15. Two simple finite element methods for Reissner--Mindlin plates with clamped boundary condition

    OpenAIRE

    Bishnu P. Lamichhane

    2013-01-01

    We present two simple finite element methods for the discretization of Reissner--Mindlin plate equations with {\\em clamped} boundary condition. These finite element methods are based on discrete Lagrange multiplier spaces from mortar finite element techniques. We prove optimal a priori error estimates for both methods.

  16. 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...

  17. An Efficient Single Impedance Network Three Level Z-Source Neutral Point Clamped Inverter

    Directory of Open Access Journals (Sweden)

    C.L.Kuppuswamy

    2012-07-01

    Full Text Available A multilevel inverter can eliminate the need for the step-up transformer and reduce the harmonics produced by the inverter. Although the multilevel inverter structure was initially introduced as a means of reducing the output waveform harmonic content, it was found that the dc bus voltage could be increased beyond the voltage rating of an individual power device by the use of a voltage clamping network consisting of diodes. By using voltage clamping techniques, the system KV rating can be extended beyond limits of an individual device. This paper presents Impedance (Z Source Neutral Point Clamped (NPC three level inverter with reduced number of impedance source networks and clamping diodes for non-linear loads. Earlier for a three level NPC inverter two separate impedance networks were used. But to reduce the circuit complexity without compromising with output requirement; only one impedance network is used and to substantiate this, the simulation of proposed circuit is carried out using MATLAB/Simulink for a 48 V input supply. A prototype is developed for an input voltage of 26V and the experimental results for the same are presented in this paper.

  18. A direct proofreader-clamp interaction stabilizes the Pol III replicase in the polymerization mode

    NARCIS (Netherlands)

    Jergic, Slobodan; Horan, Nicholas P.; Elshenawy, Mohamed M.; Mason, Claire E.; Urathamakul, Thitima; Ozawa, Kiyoshi; Robinson, Andrew; Goudsmits, Joris M. H.; Wang, Yao; Pan, Xuefeng; Beck, Jennifer L.; van Oijen, Antoine M.; Huber, Thomas; Hamdan, Samir M.; Dixon, Nicholas E.

    2013-01-01

    Processive DNA synthesis by the alpha epsilon theta core of the Escherichia coli Pol III replicase requires it to be bound to the beta(2) clamp via a site in the a polymerase subunit. How the epsilon proofreading exonuclease subunit influences DNA synthesis by alpha was not previously understood. In

  19. 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...

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

    International Nuclear Information System (INIS)

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

  1. Free Vibration Analysis of an Alround-Clamped Rectangular Thin Orthotropic Plate Using Taylor-Mclaurin Shape Function

    Directory of Open Access Journals (Sweden)

    D.O Onwuka

    2016-06-01

    Full Text Available A comprehensive free vibration analysis of an alround-clamped rectangular thin or thotropic plate, was carried out using Taylor- Mclaurin shape function, and Ritz method. The Taylor-Mclaurin shape function truncated at the fourth term satisfied all the boundary conditions of the alround-clamped thin orthotropic plate. The shape function was substituted into the total energy functional, which was subsequently minimized. From the minimized equation, the natural frequency equation for the clamped plate, was derived. The resulting equation was used to calculate fundamental natural frequencies of the clamped plate for various aspect ratios, p and different combinations of flexural rigidity ratios, φ. The fundamental frequencies for a clamped plate vibrating in the first mode are given in Tables1-5, for different flexural rigidities, φ and aspect ratios varying from 0.1 to 2 at increments of 0.1. The average percentage difference in the values of natural frequency for the flexural rigidity ratios, φ1, φ2, and φ3, are 1.532%,1.367% and 1.425% for different values of the aspect ratio, = ; and 1.149%, 1.506% and……..for different values of the aspect ratio, = . These average percentage differences indicate that the formulated deflection function for the clamped plate, is a very good approximation to the exact deflection function of the free vibration of a clamped rectangular thin orthotropic plate

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

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Nami, A.; Zare, F.; Ledwich, G.; Ghosh, A.

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

  3. 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.

  4. Short Hypoxia Does not Affect Plasma Leptin in Healthy Men under Euglycemic Clamp Conditions

    Directory of Open Access Journals (Sweden)

    Andre Schmoller

    2009-01-01

    Full Text Available Leptin is involved in the endocrine control of energy expenditure and body weight regulation. Previous studies emphasize a relationship between hypoxic states and leptin concentrations. The aim of this study was to investigate the effects of acute hypoxia on leptin concentrations in healthy subjects. We examined 14 healthy men. Hypoxic conditions were induced by decreasing oxygen saturation to 75% for 30 minutes. Plasma leptin concentrations were determined at baseline, after 3 hours of euglycemic clamping, during hypoxia, and repeatedly the following 2.5 hours thereafter. Our results show an increase of plasma leptin concentrations in the course of 6 hours of hyperinsulinemic-euglycemic clamping which may reflect diurnal rhythmicity. Notwithstanding, there was no difference between levels of leptin in the hypoxic and the normoxic condition (=.2. Since we did not find any significant changes in leptin responses upon hypoxia, plasma leptin levels do not seem to be affected by short hypoxic episodes of moderate degree.

  5. Membrane tether formation from voltage-clamped outer hair cells using optical tweezers

    Science.gov (United States)

    Qian, Feng; Ermilov, Sergey A.; Murdock, David R.; Brownell, William E.; Anvari, Bahman

    2004-06-01

    Outer hair cells contribute an active mechanical feedback to the vibrations of the cochlear structures resulting in the high sensitivity and frequency selectivity of normal hearing. We have designed and implemented a novel experimental setup that combines optical tweezers with patch-clamp apparatus to investigate the electromechanical properties of cellular plasma membranes. A micron-size bead trapped by the optical tweezers is brought in contact with the membrane of a voltage-clamped cell, and subsequently moved away to form a plasma membrane tether. Bead displacement during tether elongation is monitored by a quadrant photodetector to obtain time-resolved measurements of the tethering force. Salient information associated with the mechanical properties of the membrane tether can thus be obtained. Tethers can be pulled from the cell membrane at different holding potentials, and the tether force response can be measured while changing transmembrane potential. Experimental results from outer hair cells and human embryonic kidney cells are presented.

  6. Detailed Theoretical Model for Adjustable Gain-Clamped Semiconductor Optical Amplifier

    Directory of Open Access Journals (Sweden)

    Lin Liu

    2012-01-01

    Full Text Available The adjustable gain-clamped semiconductor optical amplifier (AGC-SOA uses two SOAs in a ring-cavity topology: one to amplify the signal and the other to control the gain. The device was designed to maximize the output saturated power while adjusting gain to regulate power differences between packets without loss of linearity. This type of subsystem can be used for power equalisation and linear amplification in packet-based dynamic systems such as passive optical networks (PONs. A detailed theoretical model is presented in this paper to simulate the operation of the AGC-SOA, which gives a better understanding of the underlying gain clamping mechanics. Simulations and comparisons with steady-state and dynamic gain modulation experimental performance are given which validate the model.

  7. Simplified Estimating Method for Shock Response Spectrum Envelope of V-Band Clamp Separation Shock

    Science.gov (United States)

    Iwasa, Takashi; Shi, Qinzhong

    A simplified estimating method for the Shock Response Spectrum (SRS) envelope at the spacecraft interface near the V-band clamp separation device has been established. This simplified method is based on the pyroshock analysis method with a single degree of freedom (D.O.F) model proposed in our previous paper. The parameters required in the estimating method are only geometrical information of the interface and a tension of the V-band clamp. According to the use of these parameters, a simplified calculation of the SRS magnitude at the knee frequency is newly proposed. By comparing the estimation results with actual pyroshock test results, it was verified that the SRS envelope estimated with the simplified method appropriately covered the pyroshock test data of the actual space satellite systems except some specific high frequency responses.

  8. 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.

  9. Experimental validation of new mathematical solutions for orthotropic plates with clamped edges

    Science.gov (United States)

    Sprinťu, Iuliana; Roateşi, Simona

    2013-10-01

    This paper deals with analytical solutions for the bending deformation of rectangular orthotropic elastic composite plates with various boundary conditions. The models are based on the classical laminated plate theory (CLPT). The Ritz method, in conjunction with the weighted residue method for the coefficients calculation is used to analytically determine the bending solutions of orthotropic laminated plates subjected to uniform pressure on the bottom laminate, having clamped edges or possessing two opposite edges simply supported and the remaining two edges clamped, respectively. Numerical examples of laminated plates considering similar boundary value problems as treated analytically are presented. It is presented the experimental device and the experimental test results, as well. Thorough comparison between analytical solutions, numerical results and experimental data is performed and a good agreement is obtained.

  10. Anthropomorphizing the Mouse Cardiac Action Potential via a Novel Dynamic Clamp Method

    Science.gov (United States)

    Ahrens-Nicklas, Rebecca C.; Christini, David J.

    2009-01-01

    Abstract Interspecies differences can limit the translational value of excitable cells isolated from model organisms. It can be difficult to extrapolate from a drug- or mutation-induced phenotype in mice to human pathophysiology because mouse and human cardiac electrodynamics differ greatly. We present a hybrid computational-experimental technique, the cell-type transforming clamp, which is designed to overcome such differences by using a calculated compensatory current to convert the macroscopic electrical behavior of an isolated cell into that of a different cell type. We demonstrate the technique's utility by evaluating drug arrhythmogenicity in murine cardiomyocytes that are transformed to behave like human myocytes. Whereas we use the cell-type transforming clamp in this work to convert between mouse and human electrodynamics, the technique could be adapted to convert between the action potential morphologies of any two cell types of interest. PMID:19917221

  11. Duration of Cord Clamping and Neonatal Outcomes in Very Preterm Infants.

    Directory of Open Access Journals (Sweden)

    Dongli Song

    Full Text Available Delayed cord clamping (DCC, ≥30 s increases blood volume in newborns and is associated with fewer blood transfusions and short-term neonatal complications. The optimal timing of cord clamping for very preterm infants should maximize placental transfusion without interfering with stabilization and resuscitation.We compared the effect of different durations of DCC, 30-45 s vs. 60-75 s, on delivery room (DR and neonatal outcomes in preterm infants 48 hours of antenatal steroid exposure. There was no difference between the two groups in neonatal death, intraventricular hemorrhage, chronic lung disease, late onset sepsis, necrotizing enterocolitis and severe retinopathy of prematurity.In this study cohort increasing DCC duration from 30-45 s to 60-75 s is associated with decreased hypothermia on admission, neonatal respiratory interventions and red blood cell transfusions without increase in neonatal mortality and morbidities.

  12. The effect of adrenergic β2 receptor agonist on paraplegia following clamping of abdominal aorta

    OpenAIRE

    Lee, Bok Y.; Al-Waili, Noori; Butler, Glenn

    2011-01-01

    Introduction Surgical repair of an aortic aneurysm might be complicated by spinal cord injury and paraplegia. Since β-adrenoreceptor agonists showed neuroprotective effects, the study was designed to investigate the effect of clenbuterol on post-aortic clamping paraplegia and to identify if there is hyperemia associated with paraplegia. Material and methods Material and methods: Thirty rabbits were divided into two groups: 15 control and 15 experimental (given clenbuterol 9 mg in drinking wat...

  13. Ionic diffusion in voltage-clamped isolated cardiac myocytes. Implications for Na,K-pump studies.

    OpenAIRE

    Mogul, D J; Singer, D H; ten Eick, R E

    1989-01-01

    The whole-cell voltage-clamp technique employing electrolyte-filled micro-pipette suction electrodes is widely used to investigate questions requiring an electrophysiological approach. With this technique, the ionic composition of the cytosol is assumed to be strongly influenced (as result of diffusion) by the ionic composition of the solution contained in the electrode. If this assumption is valid for isolated cardiac myocytes, the technique would be particularly powerful for studying the de...

  14. Evidence for cooperativity between nicotinic acetylcholine receptors in patch clamp records.

    OpenAIRE

    Keleshian, A M; Edeson, R. O.; G.J. Liu; Madsen, B W

    2000-01-01

    It is often assumed that ion channels in cell membrane patches gate independently. However, in the present study nicotinic receptor patch clamp data obtained in cell-attached mode from embryonic chick myotubes suggest that the distribution of steady-state probabilities for conductance multiples arising from concurrent channel openings may not be binomial. In patches where up to four active channels were observed, the probabilities of two or more concurrent openings were greater than expected,...

  15. Direct Tensile Strength of Steel Fiber Reinforced Concrete by Using Clamping Grips

    OpenAIRE

    ISHIGURO, Satoru; NAKAYA, Mitsuo

    1985-01-01

    This report presents the tensile strength behavior of steel fiber reinforced concrete (SFRC). In this experimental work, direct tensile test by using clamping grips is carried out for the prismatic mortar and concrete specimens reinforced with steel fibers. The volume content of steel fibers varies from 1.0 percent to 2.0 percent of the concrete volume. Test results for different fiber content, fiber length, and specimen size are presented. The results are compared with the results of indirec...

  16. A clinical comparative analysis of crush/clamp, stapler, and dissecting sealer hepatic transection methods1

    OpenAIRE

    Castaldo, Eric T.; Earl, T. Mark; Chari, Ravi S.; Gorden, D. Lee; Merchant, Nipun B; Wright, J. Kelly; Feurer, Irene D; Pinson, C Wright

    2008-01-01

    Introduction. Several methods for hepatic parenchymal division exist. The primary aim was to assess differences in postoperative bile leaks, operative blood loss, and margin status between three transection methods: crush/clamp (CC), stapler (SP), or dissecting sealer (DS). Methods. A single institution, retrospective cohort study was performed on data collected over a three-year period in patients undergoing elective liver resection using the CC, SP, or DS. Patients were excluded if multiple...

  17. 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; Perrier, Jean-Francois Marie

    2010-01-01

    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...... currents (IPSCs) remains constant. These preliminary data suggest that inhibitory and excitatory synaptic connections are balanced locally while excitation dominates long-range connections in the spinal cord....

  18. Study of hepatocellular function in the murine model following hepatic artery selective clamping

    OpenAIRE

    Tralhão, JG; Abrantes, AM; Gonçalves, AC; Hoti, E.; Laranjo, M; Martins, R.; Oliveiros, B.; Cardoso, D; Sarmento-Ribeiro, AB; Botelho, MF; Castro e Sousa, F

    2013-01-01

    PURPOSE: To investigate the impact of selective hepatic artery clamping (SHAC) in hepatocellular function. METHODS: Three groups of Wistar male rats were subjected to SHAC ischemia period of 60min: Group A continuous SHAC were subjected to SHAC ischemia period of 60min, Group B intermittent SHAC of 30min with 5min of reperfusion and Group C intermittent SHAC of 15min with 5min of reperfusion. Animals without SHAC were included-Group D. To evaluate hepatocellular function blood marker...

  19. Resolution of DNA molecules greater than 5 megabases by contour-clamped homogeneous electric fields.

    OpenAIRE

    Vollrath, D; Davis, R.W.

    1987-01-01

    Excellent resolution of chromosomal DNA molecules from Saccharomyces cerevisiae, Candida albicans and Schizosaccharomyces pombe has been obtained using alternating contour-clamped homogeneous electric field (CHEF) gel electrophoresis. The largest of these molecules is greater than 5 Mb in size and is resolved after 130 hours in a 0.6% agarose gel at a field strength of 1.3 V/cm and a switching interval of 1 hour. Separation of concatamers of phage lambda DNA reveals four regions of resolution...

  20. High Speed On-Off Valve Self-adapting Clamping System

    OpenAIRE

    Bing Wang

    2014-01-01

    The high-speed switch electromagnetic valve was a new type of element in the electro-hydraulic control system. The study aimed at the functional requirements and technical specifications of the turbine governor system for high speed on-off valve, designed the new Pulse Width Modulation high speed on-off valve. The high speed on-off valve could control fixture clamping force. Through the analysis of the working characteristics of the hydraulic actuator and h...

  1. Development of a computer interface for a clamp-on ultrasonic flow meter

    OpenAIRE

    Sundin, Peter

    2007-01-01

    The section for volume, flow and temperature at SP Technical Research Institute of Sweden performs measurements of volume, flow and temperature in liquids. Flow meters are best calibrated in its installation to take sources of error like installation effects and the medium into account. If this can be done without having to place measurement equipment inside the pipe it will mean several practical benefits. Since many years, clamp-on ultrasonic flow meters have been available on the market. B...

  2. Higher Accurate Estimation of Axial and Bending Stiffnesses of Plates Clamped by Bolts

    Science.gov (United States)

    Naruse, Tomohiro; Shibutani, Yoji

    Equivalent stiffness of clamped plates should be prescribed not only to evaluate the strength of bolted joints by the scheme of “joint diagram” but also to make structural analyses for practical structures with many bolted joints. We estimated the axial stiffness and bending stiffness of clamped plates by using Finite Element (FE) analyses while taking the contact condition on bearing surfaces and between the plates into account. The FE models were constructed for bolted joints tightened with M8, 10, 12 and 16 bolts and plate thicknesses of 3.2, 4.5, 6.0 and 9.0 mm, and the axial and bending compliances were precisely evaluated. These compliances of clamped plates were compared with those from VDI 2230 (2003) code, in which the equivalent conical compressive stress field in the plate has been assumed. The code gives larger axial stiffness for 11% and larger bending stiffness for 22%, and it cannot apply to the clamped plates with different thickness. Thus the code shall give lower bolt stress (unsafe estimation). We modified the vertical angle tangent, tanφ, of the equivalent conical by adding a term of the logarithm of thickness ratio t1/t2 and by fitting to the analysis results. The modified tanφ can estimate the axial compliance with the error from -1.5% to 6.8% and the bending compliance with the error from -6.5% to 10%. Furthermore, the modified tanφ can take the thickness difference into consideration.

  3. A helping clamp for thoracoscopic plication of eventration of the diaphragm

    OpenAIRE

    Reju Joseph Thomas; Ravi Kishore; Sundeep Kisku

    2011-01-01

    Background and Aim: It is difficult to suture an extremely thin and billowed up congenital eventration of the diaphragm thoracoscopically, without insufflation. Materials and Methods: The authors describe their technique using an intestinal clamp to control the redundant tissue and a feeding tube as a flexible knot pusher, to perform the thoracoscopic plication without risking hypercapnia. Results: A satisfactory result was obtained in all the four children. Conclusion: This is a useful adjun...

  4. A helping clamp for thoracoscopic plication of eventration of the diaphragm

    Directory of Open Access Journals (Sweden)

    Reju Joseph Thomas

    2011-01-01

    Full Text Available Background and Aim: It is difficult to suture an extremely thin and billowed up congenital eventration of the diaphragm thoracoscopically, without insufflation. Materials and Methods: The authors describe their technique using an intestinal clamp to control the redundant tissue and a feeding tube as a flexible knot pusher, to perform the thoracoscopic plication without risking hypercapnia. Results: A satisfactory result was obtained in all the four children. Conclusion: This is a useful adjunctive for thoracoscopic plication of diaphragmatic eventration.

  5. Prediction of numerical distortion after welding with various welding sequences and clampings

    OpenAIRE

    S. Kastelic; J. Medved; Mrvar, P.

    2010-01-01

    Welding simulation of a test cover for hydropower plant was made due to very large dimensions of the cover. The main aim was to predict distortion after welding in order to avoid machining the cover. Welding process was simulated with the Sysweld program to keep distortion in desired limits. Various welding sequences and clamping conditions were calculated to reduce the distortion. Calculation of microstructure constituents in virtual complex geometry of joints was also analyzed.

  6. Efficient Power Conversion in Common Active Clamp for Interleaved Dc-Dc Boost

    Directory of Open Access Journals (Sweden)

    V. Rathinavel Subramaniam

    2014-10-01

    Full Text Available This project presents a high-efficiency and high-step-up non isolated interleaved dc to dc converter with a common active-clamp circuit. In the presented converter, the coupled-inductor boost converters are interleaved. A boost converter is used to clamp the voltage stresses of all the switches in the interleaved converters, caused by the leakage inductances present in the practical coupled inductors, to a low voltage level. The leakage energies of the inter-leaved converters are collected in a clamp capacitor and recycled to the output by the clamp boost converter. The proposed converter achieves high efficiency because of the recycling of the leakage energies, reduction of the switch voltage stress, mitigation of the output diode is reverse recovery problem, and interleaving of the converters. In many applications, high-efficiency, high-voltage step-up dc–dc converters are required as an interface between the available low voltage sources and the output loads, which are operated at much higher voltages. Examples of such applications are as follows. Different distributed energy storage components such as batteries, fuel cells, and ultra capacitors are used in the power trains of hybrid electric vehicles (HEV, electric vehicles (EV, and fuel cell vehicles (FCV. In the present power train architectures of these vehicles, the voltage levels of the energy storage elements are usually low; whereas the motors of the vehicles are driven at much higher voltages. The telecom and the computer industry utilize the standard batteries, with low voltage levels, as a back-up power source. The dc–dc converter, used in this case, is required to boost the low-input voltage of the batteries to the high voltage of the dc bus. Another example is the automotive headlamps, using the high-intensity discharge lamp ballasts..

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

    OpenAIRE

    C. H. Chang; Cheng, H L; C. A. Cheng; E. C. Chang

    2013-01-01

    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...

  8. Photoluminescence clamping with few excitons in a single-walled carbon nanotube

    OpenAIRE

    Xiao, Y. -F.; Nhan, T. Q.; Wilson, M. W. B.; Fraser, J. M.

    2009-01-01

    Single air-suspended carbon nanotubes (length 2 - 5 microns) exhibit high optical quantum efficiency (7 - 20%) for resonant pumping at low intensities. Under ultrafast excitation, the photoluminescence dramatically saturates for very low injected exciton numbers (2 to 6 excitons per pulse per SWCNT). This PL clamping is attributed to highly efficient exciton-exciton annihilation over micron length scales. Stochastic modeling of exciton dynamics and femtosecond excitation correlation spectrosc...

  9. What we talk about when we talk about capacitance measured with the voltage-clamp step method

    OpenAIRE

    Taylor, Adam L.

    2011-01-01

    Capacitance is a fundamental neuronal property. One common way to measure capacitance is to deliver a small voltage-clamp step that is long enough for the clamp current to come to steady state, and then to divide the integrated transient charge by the voltage-clamp step size. In an isopotential neuron, this method is known to measure the total cell capacitance. However, in a cell that is not isopotential, this measures only a fraction of the total capacitance. This has generally been thought ...

  10. A capacitor-clamped inverter based torsional oscillation damping method for electromechanical drivetrains

    Directory of Open Access Journals (Sweden)

    Shagar Viknash

    2016-01-01

    Full Text Available A typical electromechanical drivetrain consists of an electric motor, connecting shafts and gears. Premature failures of these shafts and gears have been reported which are mainly due to fatigue caused by extreme loads and torsional oscillations. Overdesign and passive damping are the common approaches taken to increase the fatigue life. Nevertheless, they increase the system cost, weight and volume. Alternatively, active damping through advanced inverter control of the motor drive has been identified as a promising solution that does not require overdesign or alterations to the existing system. Even with the active damping control, oscillations propagate into the dc side of the power converter and subsequently to the upstream power bus. Generally, a large capacitor or an additional energy storage system is placed to suppress these oscillations. This paper proposes to use the clamping capacitors of the capacitor-clamped inverter as energy storage elements and thereby eliminate the need for a large dc side capacitor or an additional energy storage system. The efficacy of the proposed method has been verified with computer simulations. Simulation results show that the clamping capacitors are capable of containing torsional oscillations within the inverter without passing them to the upstream power bus.

  11. 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.

  12. 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.

  13. A phage-encoded inhibitor of Escherichia coli DNA replication targets the DNA polymerase clamp loader.

    Science.gov (United States)

    Yano, Sho T; Rothman-Denes, Lucia B

    2011-03-01

    Coliphage N4 infection leads to shut-off of host DNA replication without inhibition of host transcription or translation. We report the identification and characterization of gp8, the N4 gene product responsible for this phenotype. N4 gp8 is an Escherichia coli bacteriostatic inhibitor that colocalizes with the E. coli replisome in a replication-dependent manner. Gp8 was purified and observed to cross-link to complexes containing the replicative DNA polymerase, DNAP III, in vivo. Purified gp8 inhibits DNA polymerization by DNA polymerase III holoenzyme in vitro by interfering with polymerase processivity. Gp8 specifically inhibits the clamp-loading activity of DNAP III by targeting the delta subunit of the DNAP III clamp loader; E. coli mutations conferring gp8 resistance were identified in the holA gene, encoding delta. Delta and gp8 interact in vitro; no interaction was detected between gp8 inactive mutants and wild-type delta or between delta gp8-resistant mutants and wild-type gp8. Therefore, this work identifies the DNAP III clamp loader as a new target for inhibition of bacterial growth. Finally, we show that gp8 is not essential in N4 development under laboratory conditions, but its activity contributes to phage yield. PMID:21205014

  14. Molecular jamming--the cystine slipknot mechanical clamp in all-atom simulations.

    Science.gov (United States)

    Pepłowski, Lukasz; Sikora, Mateusz; Nowak, Wiesław; Cieplak, Marek

    2011-02-28

    A recent survey of 17 134 proteins has identified a new class of proteins which are expected to yield stretching induced force peaks in the range of 1 nN. Such high force peaks should be due to forcing of a slip-loop through a cystine ring, i.e., by generating a cystine slipknot. The survey has been performed in a simple coarse grained model. Here, we perform all-atom steered molecular dynamics simulations on 15 cystine knot proteins and determine their resistance to stretching. In agreement with previous studies within a coarse grained structure based model, the level of resistance is found to be substantially higher than in proteins in which the mechanical clamp operates through shear. The large stretching forces arise through formation of the cystine slipknot mechanical clamp and the resulting steric jamming. We elucidate the workings of such a clamp in an atomic detail. We also study the behavior of five top strength proteins with the shear-based mechanostability in which no jamming is involved. We show that in the atomic model, the jamming state is relieved by moving one amino acid at a time and there is a choice in the selection of the amino acid that advances the first. In contrast, the coarse grained model also allows for a simultaneous passage of two amino acids. PMID:21361557

  15. Molecular jamming—The cystine slipknot mechanical clamp in all-atom simulations

    Science.gov (United States)

    Pepłowski, Łukasz; Sikora, Mateusz; Nowak, Wiesław; Cieplak, Marek

    2011-02-01

    A recent survey of 17 134 proteins has identified a new class of proteins which are expected to yield stretching induced force peaks in the range of 1 nN. Such high force peaks should be due to forcing of a slip-loop through a cystine ring, i.e., by generating a cystine slipknot. The survey has been performed in a simple coarse grained model. Here, we perform all-atom steered molecular dynamics simulations on 15 cystine knot proteins and determine their resistance to stretching. In agreement with previous studies within a coarse grained structure based model, the level of resistance is found to be substantially higher than in proteins in which the mechanical clamp operates through shear. The large stretching forces arise through formation of the cystine slipknot mechanical clamp and the resulting steric jamming. We elucidate the workings of such a clamp in an atomic detail. We also study the behavior of five top strength proteins with the shear-based mechanostability in which no jamming is involved. We show that in the atomic model, the jamming state is relieved by moving one amino acid at a time and there is a choice in the selection of the amino acid that advances the first. In contrast, the coarse grained model also allows for a simultaneous passage of two amino acids.

  16. Is Near-Infrared Spectroscopy a Reliable Method to Evaluate Clamping Ischemia during Carotid Surgery?

    Directory of Open Access Journals (Sweden)

    Luciano Pedrini

    2012-01-01

    Full Text Available Guidelines do not include cerebral oximetry among monitoring for carotid endarterectomy (CEA. The purpose of this study was to evaluate the reliability of near-infrared spectroscopy (NIRS in the detection of clamping ischemia and in the prevention of clamping-related neurologic deficits using, as a cutoff for shunting, a 20% regional cerebral oxygen saturation (rSO2 decrease if persistent more than 4 minutes, otherwise a 25% rSO2 decrease. Bilateral rSO2 was monitored continuously in patients undergoing CEA under general anesthesia (GA. Data was recorded after clamping, declamping, during shunting and lowest values achieved. Preoperative neurologic, CT-scan, and vascular lesions were recorded. We reviewed 473 cases: 305 males (64.5% mean age 73.3±7.3. Three patients presented transient ischemic deficits at awakening, no perioperative stroke or death; 41 (8.7% required shunting: 30 based on the initial rSO2 value and 11 due to a decrease during surgery. Using the ROC curve analysis we found, for a >25% reduction from baseline value, a sensitivity of 100% and a specificity of 90.6%. Reliability, PPV, and NPV were 95.38%, 9%, and 100%, respectively. In conclusion, this study indicates the potential reliability of NIRS monitoring during CEA under GA, using a cutoff of 25% or a cutoff of 20% for prolonged hypoperfusion.

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    Noor Ul Hassan

    2016-04-01

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

  19. In vivo measurements of whole body (WB) and skeletal muscle glucose metabolism under basal and euglycemic insulin clamp (Clamp) by combined PET and stable isotope (SI) tracer studies

    International Nuclear Information System (INIS)

    Aim/Background: Primed-constant infusion of SI labeled tracers is a classic technique for studying metabolism at the WB level, however, this procedure provides no information about the metabolism of specific tissues. In contrast PET provides primarily tissue specific data. In this study, we combined PET with SI techniques to measure glucose metabolism in WB and lower limb skeletal muscle (LLM) of humans under Basal and Clamp conditions. Methods and Materials: Four healthy volunteers (73.0 ± 6.0 kg, mean ± sem) were studied. After fasting overnight, each subject was injected with 10 mCi of 18FDG and serial 1.0 min. PET images of the mid-thigh region were acquired over 90 min. Arterial blood samples were collected in parallel. Glucose metabolic rate (GM) was calculated with a 3-compartment / 4 rate constant model; LC assumed to be 1.0. A primed constant infusion of [6,6, 2H2]glucose was performed in parallel with the PET measurements. On another day, the PET and SI measurements were repeated under clamp conditions. All results are expressed as mean ± sem. Results: The glucose kinetics in whole body and in low limb skeletal muscles are shown. Under in vivo conditions, Clamp caused: 1) a 10.2 ± 2.3 fold increase in GM by LLM but only a 4.7 ± 0.4 fold increase in GM by MB. 2) Increased contribution of LLM to WB GM, indicating that LLM GM is more sensitive to insulin compared with anterior LLM (extensors). Discussion: The study demonstrated the unique advantages of using PET to study substrate metabolism in specific tissues in human subjects: i) It is less invasive than the conventional A-V difference and muscle biopsy method. ii) It provides a more detailed picture of substrate metabolism in different parts of the muscle in the same limb, as compared to one spot muscle biopsy. Data in demonstrated that GM in posterior LLM is more sensitive to insulin than that in anterior LLM. iii) It can detect substrate metabolism in deep muscles which cannot be reached by biopsy

  20. 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.

  1. Robotic clamp and index tool and method for their use in repairing certain elements with in a nuclear reactor

    International Nuclear Information System (INIS)

    This patent describes a clamp-and-index tool for use in the replacement of old split-pin assemblies of a guide tube of a nuclear reactor by new split-pin assemblies, the old split-pin assemblies and the guide tube being radioactive and the clamp-and-index tool to operate under a pool of water. The tool includes means, to be connected to the guide tube, for suspending the guide tube in a first position in which the tube is to be processed to effect the replacement. The tool also includes a means, connected to the suspending means, for rotating the guide tube to a second position in which the tube is to be processed to effect the replacement and clamping means, connected to the suspending means and to be connected to the guide tube, for selectively clamping the guide tube in the first or second position

  2. Structure-function analysis of the C-clamp of TCF/Pangolin in Wnt/ß-catenin signaling.

    Directory of Open Access Journals (Sweden)

    Aditi J Ravindranath

    Full Text Available The evolutionarily conserved Wnt/ß-catenin (Wnt/ß-cat pathway plays an important role in animal development in metazoans. Many Wnt targets are regulated by members of the TCF/LEF1 (TCF family of transcription factors. All TCFs contain a High Mobility Group (HMG domain that bind specific DNA sequences. Invertebrate TCFs and some vertebrate TCF isoforms also contain another domain, called the C-clamp, which allows TCFs to recognize an additional DNA motif known as the Helper site. While the C-clamp has been shown to be important for regulating several Wnt reporter genes in cell culture, its physiological role in regulating Wnt targets is less clear. In addition, little is known about this domain, except that two of the four conserved cysteines are functionally important. Here, we carried out a systematic mutagenesis and functional analysis of the C-clamp from the Drosophila TCF/Pangolin (TCF/Pan protein. We found that the C-clamp is a zinc-binding domain that is sufficient for binding to the Helper site. In addition to this DNA-binding activity, the C-clamp also inhibits the HMG domain from binding its cognate DNA site. Point mutations were identified that specifically affected DNA-binding or reduced the inhibitory effect. These mutants were characterized in TCF/Pan rescue assays. The specific DNA-binding activity of the C-clamp was essential for TCF/Pan function in cell culture and in patterning the embryonic epidermis of Drosophila, demonstrating the importance of this C-clamp activity in regulating Wnt target gene expression. In contrast, the inhibitory mutation had a subtle effect in cell culture and no effect on TCF/Pan activity in embryos. These results provide important information about the functional domains of the C-clamp, and highlight its importance for Wnt/ß-cat signaling in Drosophila.

  3. The Analysis of Clamping Mechanism Theory and the Application Design of Tobacco Leaves'Clamping Tool%夹紧机构的理论分析及烘烤烟叶夹的应用设计

    Institute of Scientific and Technical Information of China (English)

    徐远龙; 孙有祥

    2011-01-01

    In view of the complicated manual skill of the tobacco leaf weaving, the study and design of a kind tool clamping tobacco leaf is proposed by our actual investigation; According to the predetermined function demand and the available clamping mechanism, the principle of the clamping tool is studied out, the structural design scheme of the clamping tool is worked out and the clamping tool is made by the theory analysis of mechanism design and the study of clamping mechanism. The clamping tool tested by the surveyor is good in use, which is welcome to use by the peasants and the economy benefit of the market can be achieved highly.%通过对烟叶烘烤生产工艺的实际调研,针对手工繁杂的编烟技术,提出了研究设计一种烘烤烟叶夹持工具;针对烘烤烟叶夹的预定功能要求,参考现有的实用夹紧机构,通过对机械产品机构设计的理论分析和夹紧机构的力学研究,确定了夹紧烟叶的力学原理,提出了烘烤烟叶夹的结构设计方案,设计制造出烘烤烟叶夹;该烘烤烟叶夹通过了产品的质量检测,使用效果良好,烟农用户普遍接受使用,预计有较高的市场经济效益.

  4. Clamping end-tidal carbon dioxide during graded exercise with control of inspired oxygen.

    Science.gov (United States)

    Farra, Saro D; Kessler, Cathie; Duffin, James; Wells, Greg D; Jacobs, Ira

    2016-09-01

    Exercise- and hypoxia-induced hyperventilation decreases the partial pressure of end-tidal carbon dioxide (PETCO2), which in turn exerts many physiological effects. Several breathing circuits that control PETCO2 have been previously described, but their designs are not satisfactory for exercise studies where changes in inspired oxygen (FIO2) may be desired. This study is the first report of a breathing system that can maintain PETCO2 constant within a single session of graded submaximal exercise and graded hypoxia. Thirteen fit and healthy subjects completed two bouts of exercise consisting of three 3min stages on a cycle ergometer with increasing exercise intensity in normoxia (Part A; 142±14, 167±14, 192±14W) or with decreasing FIO2 at a constant exercise intensity (Part B; 21, 18, and 14%). One bout was a control (CON) where PETCO2 was not manipulated, while during the other bout the investigator clamped PETCO2 within 2mmHg (CO2Clamp) using sequential gas delivery (SGD). During the final 30s of each exercise stage during CO2Clamp, PETCO2 was successfully maintained in Part A (43±4, 44±4, 44±3mmHg; P=0.44) and Part B (45±3, 46±3, 45±3mmHg; P=0.68) despite the increases in ventilation due to exercise. These findings demonstrate that this SGD circuit can be used to maintain isocapania in exercising humans during progressively increasing exercise intensities and changing FIO2. PMID:27236039

  5. Plasmodium falciparum: analysis of chromosomes separated by contour-clamped homogenous electric fields.

    Science.gov (United States)

    Gu, H; Inselburg, J W; Bzik, D J; Li, W B

    1990-08-01

    We have established improved conditions for separating the chromosomes of Plasmodium falciparum by pulsed field gradient gel electrophoresis (PFG) using a contour-clamped homogenous electric field (CHEF) apparatus. Thirteen clearly separable chromosomal bands were reproducibly isolated from the strain FCR3 and their sizes have been determined. Evidence that indicates one band may contain two chromosomes is presented. The relationship between the PFG separable DNA and the number of unique chromosomes in P. falciparum is considered. We have established a relationship between the maximum resolvable sizes of the chromosomes and the pulse times. The chromosomal location of twenty-seven P. falciparum DNA probes is also reported. PMID:2197113

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

    DEFF Research Database (Denmark)

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

    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...... method, with the ability to easily adjust for capacitor voltage imbalances. To further improve the boost capability of the three-level NPC inverters, another new topology introduces 2 additional diodes,achieving higher boost performance while totally eliminating thepossibility of capacitor voltage...

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

    DEFF Research Database (Denmark)

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

    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-voltage...... stress across the inverter bridge and poor output voltage spectrum. As alternatives with improved performances, two transformer-based Z-source NPC inverters are proposed, whose gain can be adjusted by varying the transformer turns ratio, and is hence less dependent on the inverter modulation ratio...

  8. HERG channel (dys)function revealed by dynamic action potential clamp technique

    OpenAIRE

    Berecki, G; Zegers, J.G.; Verkerk, A.O.; Bhuiyan, Z.A.; Jonge, de, M.J.I.; Veldkamp, M.W.; Wilders, R; Ginneken, van, CJJM Kees

    2005-01-01

    The human ether-a-go-go-related gene (HERG) encodes the rapid component of the cardiac delayed rectifier potassium current (IKr). Per-Arnt-Sim domain mutations of the HERG channel are linked to type 2 long-QT syndrome. We studied wild-type and/or type 2 long-QT syndrome-associated mutant (R56Q) HERG current (IHERG) in HEK-293 cells, at both 23 and 36°C. Conventional voltage-clamp analysis revealed mutation-induced changes in channel kinetics. To assess functional implication(s) of the mutatio...

  9. Strong localization induced by one clamped point in thin plate vibrations.

    Science.gov (United States)

    Filoche, Marcel; Mayboroda, Svitlana

    2009-12-18

    We discover a strong localization of flexural (bi-Laplacian) waves in rigid thin plates. We show that clamping just one point inside such a plate not only perturbs its spectral properties, but essentially divides the plate into two independently vibrating regions. This effect progressively appears when increasing the plate eccentricity. Such a localization is qualitatively and quantitatively different from the results known for the Laplacian waves in domains of irregular boundary. It would allow us to control the confinement of mechanical vibrations in rigid plates and of eddies in the slow Stokes flow. PMID:20366256

  10. Sodium influxes in internally perfused squid giant axon during voltage clamp.

    Science.gov (United States)

    Atwater, I; Bezanilla, F; Rojas, E

    1969-05-01

    1. An experimental method for measuring ionic influxes during voltage clamp in the giant axon of Dosidicus is described; the technique combines intracellular perfusion with a method for controlling membrane potential.2. Sodium influx determinations were carried out while applying rectangular pulses of membrane depolarization. The ratio ;measured sodium influx/computed ionic flux during the early current' is 0.92 +/- 0.12.3. Plots of measured sodium influx and computed ionic flux during the early current against membrane potential are very similar. There was evidence that the membrane potential at which the sodium influx vanishes is the potential at which the early current reverses. PMID:5767887

  11. Thermal and Efficiency Analysis of Five-Level Multilevel-Clamped Multilevel Converter Considering Grid Codes

    DEFF Research Database (Denmark)

    Ma, Ke; Muñoz-Aguilar, R. S.; Rodriguez, Pedro; Blaabjerg, Frede

    2014-01-01

    In this paper, a five-level multilevel-clamped multilevel converter (5L- MLC2) topology is analyzed based on a typical grid integration application for renewable energy system. The loss and thermal distributions of the power devices in different switching legs are investigated and illustrated under...... rated condition. Afterward, a loss and efficiency evaluation method is proposed and applied which takes into account various injected reactive power ranges regulated by the grid codes. It is concluded that the loss and thermal distributions of the 5L- MLC2 multilevel topology are unequal between the...

  12. 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.

  13. Modeling of Busbars in High Power Neutral Point Clamped Three-Level Inverters

    Institute of Scientific and Technical Information of China (English)

    YI Rung; ZHAO Zhengming; ZHONG Yulin

    2008-01-01

    The busbars in high power neutral point clamped three-level inverters are modeled using the Maxwell Q3D Extractor software, which is based on the partial element equivalent circuits method. The equivalent circuits of the busbars and devices model are simulated in the electric simulator PSIM to analyze the effects of the parasitic inductance on the switching characteristics of the integrated gate commutatedthyristor (IGCT) in different topology positions. The simulation results agree well with the measured imped-ance analyzer results and the IGCT test results, which proves the effectiveness of the modeling method for the large, complex busbars.

  14. 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)

  15. A broadly tunable fiber ring laser employing a gain-clamped semiconductor optical amplifier

    International Nuclear Information System (INIS)

    A widely tunable fiber ring laser is demonstrated experimentally using a specially designed gain-clamped semiconductor optical amplifier (GC-SOA). The 3 dB bandwidth of the generated amplified spontaneous emission is increased by 10 nm using the GC-SOA. The lasing wavelength is continuously tunable in a range from 1522 nm to almost 1600 nm using a thin-film Fabry–Pérot tunable filter. A side-mode-suppression ratio of greater than 55 dB is achieved over the entire tuning range. (paper)

  16. Paired Patch Clamp Recordings from Motor-neuron and Target Skeletal Muscle in Zebrafish

    OpenAIRE

    Wen, Hua; Brehm, Paul

    2010-01-01

    Larval zebrafish represent the first vertebrate model system to allow simultaneous patch clamp recording from a spinal motor-neuron and target muscle. This is a direct consequence of the accessibility to both cell types and ability to visually distinguish the single segmental CaP motor-neuron on the basis of morphology and location. This video demonstrates the microscopic methods used to identify a CaP motor-neuron and target muscle cells as well as the methodologies for recording from each c...

  17. 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.

  18. Patch Clamp Recordings in Inner Ear Hair Cells Isolated from Zebrafish

    OpenAIRE

    Einarsson, Rachel; Haden, Marshall; DiCiolli, Gabrielle; Lim, Andrea; Mah-Ginn, Kolina; Aguilar, Kathleen; Yazejian, Lucy; Yazejian, Bruce

    2012-01-01

    Patch clamp analyses of the voltage-gated channels in sensory hair cells isolated from a variety of species have been described previously1-4 but this video represents the first application of those techniques to hair cells from zebrafish. Here we demonstrate a method to isolate healthy, intact hair cells from all of the inner ear end-organs: saccule, lagena, utricle and semicircular canals. Further, we demonstrate the diversity in hair cell size and morphology and give an example of the kind...

  19. Micro-agar salt bridge in patch-clamp electrode holder stabilizes electrode potentials

    OpenAIRE

    Shao, Xuesi M; Feldman, Jack L.

    2006-01-01

    Maintaining a stable electrode potential is critical for patch-clamp measurements. The electrode potential of conventional patch electrode-holder assembly, where an Ag/AgCl wire is in direct contact with the patch pipette filling solution, is subject to drift if the pipette solution contains a low concentration of chloride ions (Cl−). We developed an agar bridge of 3 M KCl filled in a polyimide microtubing which forms an electrical connection between an Ag/AgCl wire and the pipette solution. ...

  20. Voltage-clamp frequency domain analysis of NMDA-activated neurons.

    Science.gov (United States)

    Moore, L E; Hill, R H; Grillner, S

    1993-02-01

    1. Voltage and current-clamp steps were added to a sum of sine waves to measure the tetrodotoxin-insensitive membrane properties of neurons in the intact lamprey spinal cord. A systems analysis in the frequency domain was carried out on two types of cells that have very different morphologies in order to investigate the structural dependence of their electrophysiological properties. The method explicitly takes into account the geometrical shapes of (i) nearly spherical dorsal cells with one or two processes and (ii) motoneurons and interneurons that have branched dendritic structures. Impedance functions were analysed to obtain the cable properties of these in situ neurons. These measurements show that branched neurons are not isopotential and, therefore, a conventional voltage-clamp analysis is not valid. 2. The electrophysiological data from branched neurons were curve-fitted with a lumped soma-equivalent cylinder model consisting of eight equal compartments coupled to an isopotential cell body to obtain membrane parameters for both passive and active properties. The analysis provides a quantitative description of both the passive electrical properties imposed by the geometrical structure of neurons and the voltage-dependent ionic conductances determined by ion channel kinetics. The model fitting of dorsal cells was dominated by a one-compartment resistance and capacitance in parallel (RC) corresponding to the spherical, non-branched shape of these cells. Branched neurons required a model that contained both an RC compartment and a cable that reflected the structure of the cells. At rest, the electrotonic length of the cable was about two. Uniformly distributed voltage-dependent ionic conductance sites were adequate to describe the data at different membrane potentials. 3. The frequency domain admittance method in conjunction with a step voltage clamp was used to control and measure the oscillatory behavior induced by N-methyl-D-aspartate (NMDA) on lamprey spinal

  1. LETTER TO THE EDITOR: Stretching of proteins in a force-clamp

    Science.gov (United States)

    Szymczak, P.; Cieplak, Marek

    2006-01-01

    Mechanically induced protein unfolding in the force-clamp apparatus is shown, in a coarse-grained model of ubiquitin, to have lognormal statistics above a threshold force and exponential statistics below it. Correspondingly, the mean unfolding time is slowly varying and exponentially decreases as a function of the force. The time dependences of the end-to-end distances are also distinct. The time sequence of unfolding events weakly depends on force and much of it resembles that for stretching at constant speed. A more complicated time dependence arises for integrin.

  2. Acute hypotension induced by aortic clamp vs. PTH provokes distinct proximal tubule Na+ transporter redistribution patterns

    DEFF Research Database (Denmark)

    Leong, Patrick K K; Yang, Li E; Lin, Harrison W;

    2004-01-01

    renal cortical membranes fractionated on sorbitol density gradients. Aortic clamp-induced acute hypotension (from 100 +/- 3 to 78 +/- 2 mmHg) provoked a 62% decrease in urine output and a significant decrease in volume flow from the proximal tubule detected as a 66% decrease in endogenous lithium...... clearance. There was, however, no significant change in glomerular filtration rate (GFR) or subcellular distribution of NHE3 and NaPi2. In contrast, high-dose PTH rapidly (<2 min) decreased arterial blood pressure to 51 +/- 3 mmHg, decreased urine output, and shifted NHE3 and NaPi2 out of the low...

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

    Directory of Open Access Journals (Sweden)

    Morgan Kristen

    2011-01-01

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

  4. Impact of early versus delayed umbilical cord clamping on post partum blood loss: a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Yogiraj Vaijanathrao Chidre,Vijayalakshmi Chirumamilla

    2015-08-01

    Methods: A randomized, controlled trial was performed on 183 consenting women fulfilling eligibility criteria in labour ward of a teaching hospital in India. They were randomly assigned into early cord clamping or delayed cord clamping group; other components of active management of third stage of labour being same for all. The duration of third stage of labour was noted. Quantitative assessment of post partum blood loss was done using BRASSS-V drapes and weighing blood soaked pads. Cord blood haemoglobin and hematocrit at birth and infant haemoglobin and hematocrit at 90 +/-7 days were estimated. Statistical analysis done using students unpaired and lsquo;t' test. Results: No difference was noted in the mean blood loss (203.52 +/- 122.74 ml versus 200.74+/- 104.07 ml in early and delayed cord clamping respectively and the duration of third stage of labour (Mean: 296.59+/- 98.97 seconds versus 281.79+/-104.59 seconds for early and delayed clamping respectively. Infant haemoglobin at 90 +/-7 days was 11.07 +/- 1.27 gm/dl versus 12.70+/- 1.41 gm/dl (p=0.0000 and infant hematocrit at 90 +/-7 days was 34.13+/-3.93 % versus 39.33 +/-4.88 % in early and delayed clamping respectively (p=0.0000. Conclusion: The timing of cord clamping has no impact on the mean blood loss and duration of third stage of labour. Delayed clamping significantly increases mean venous haemoglobin and hematocrit at 90 +/-7 days without increasing NICU admissions. [Int J Reprod Contracept Obstet Gynecol 2015; 4(4.000: 1103-1108

  5. 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.

  6. 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

  7. A Clamped Be Window for the Dump of the HiRadMat Experiment at CERN

    CERN Document Server

    Delonca, M; Grenier, D; Maglioni, C; Sarrio Martinez, A

    2012-01-01

    At CERN, the High Radiation to Materials facility (HiRadMat) is designed to test accelerator components under the impact of high-intensity pulsed beams and will start operation in 2012. In this frame an LHC TED-type dump was installed at the end of the line, working in nitrogen overpressure, and a 254μm-thick beryllium window was placed as barrier between the inside of the dump and the external atmosphere. Because of the special loading conditions, a clamped window design was especially developed, optimized and implemented, the more standard welded window not being suitable for such loads. Considering then the clamping force and the applied differential pressures, the stresses on the window components were carefully evaluated thanks to empirical as well as numerical models, to guarantee the structural integrity of the beryllium foil. This paper reports on choices and optimizations that led to the final design, presenting also comparative results from different solutions and the detailed results for the adopt...

  8. Mechanically clamped PZT ceramics investigated by First-order reversal curves diagram

    Directory of Open Access Journals (Sweden)

    Laurentiu Stoleriu

    2010-09-01

    Full Text Available The First Order Reversal Curves (FORC diagrams method was developed for characterizing the switching properties of ferroelectrics. In the present paper, the FORC method was applied for hard Pb(Zr,TiO3 ceramics with symmetric and asymmetric clamping. An ideal high-oriented single-crystalline ferroelectric with rectangular P(E loop would be characterised by a delta-function FORC distribution, while real ferroelectrics and mostly the polycrystalline ceramics show dispersed FORC distributions. All the investigated ceramics show FORC distributions with non-Gaussian shape, slightly elongated along the coercitive axis, meaning a high dispersion of the energy barriers separating the two bi-stable polarizations ±P. The degree of dispersion is enhanced by clamping. The maximum FORC coercivity is located at ~ (1.9-2 MV/m for all the hard ceramics. The FORC cycling experiment causes the reversal of the initial poling and result in a positive/negative bias on the FORC diagrams. According to the observed features, it results that FORC coercivity is more related to the nature of the material, while the bias field is more sensitive to the electrical and mechanical boundary conditions in which the ferroelectric ceramics evolves while switching.

  9. MODELING, VALIDATION AND OPTIMAL DESIGN OF THE CLAMPING FORCE CONTROL VALVE USED IN CONTINUOUSLY VARIABLE TRANSMISSION

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yunshan; LIU Jin'gang; CAI Yuanchun; ZOU Naiwei

    2008-01-01

    Associated dynamic performance of the clamping force control valve used in continuously variable transmission (CVT) is optimized. Firstly, the structure and working principle of the valve are analyzed, and then a dynamic model is set up by means of mechanism analysis. For the purpose of checking the validity of the modeling method, a prototype workpiece of the valve is manufactured for comparison test, and its simulation result follows the experimental result quite well. An associated performance index is founded considering the response time, overshoot and saving energy, and five structural parameters are selected to adjust for deriving the optimal associated performance index. The optimization problem is solved by the genetic algorithm (GA) with necessary constraints. Finally, the properties of the optimized valve are compared with those of the prototype workpiece, and the results prove that the dynamic performance indexes of the optimized valve are much better than those of the prototype workpiece.Key words: Dynamic modeling Optimal design Genetic algorithm Clamping force control valve Continuously variable transmission (CVT)

  10. Influence of non-steady state during isoglycemic hyperinsulinemic clamp in hypertension. A LIFE substudy

    DEFF Research Database (Denmark)

    Olsen, M H; Andersen, U B; Wachtell, K;

    1999-01-01

    We wanted to investigate whether time to steady state was reached within 2 h of insulin infusion during isoglycemic hyperinsulinemic clamp, comparing the glucose uptake index (M/IG) with Bergman's insulin sensitivity index (Sip). We performed a 2-h oral glucose tolerance test and a 3-h isoglycemic...... hyperinsulinemic clamp in 26 young, healthy subjects and 43 elderly patients with unmedicated essential hypertension and left ventricular hypertrophy. The 3-h Sip correlated strongly with the 2-h M/IG in the patients (r = 0.88, p <0.001) as well as in the healthy subjects (r = 0.96, p <0.001) with relatively...... narrow limits of agreement in the patients. However, during the third hour of insulin infusion, M/IG (10.0 vs 12.21(2) x kg(-1) x min(-1) x mmol(-1), p <0.001) as well as Sip (7.1 vs 9.41(2) x kg(-1) x min(-1) x mmol(-1), p <0.001) increased significantly in the patients, but not in the healthy subjects...

  11. 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.

  12. 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.

  13. Estimating residual stress, curvature and boundary compliance of doubly clamped MEMS from their vibration response

    International Nuclear Information System (INIS)

    Structural parameters of doubly clamped microfabricated beams such as initial curvature, boundary compliance, thickness and mean residual stress are often critical to the performance of microelectromechanical systems (MEMS) and need to be estimated as a part of quality control of the microfabrication process. However, these parameters couple and influence many metrics of device response and thus are very difficult to disentangle and estimate using conventional methods such as the M-test, static mechanical tests, pull-in measurements or dynamic mechanical tests. Here we present a simple, non-destructive experimental method to extract these parameters based on the non-contact measurement of the natural frequencies of the lowest few eigenmodes of the microfabricated beam, and knowledge of Young's modulus and plan dimensions of the beam alone. The method exploits the fact that certain eigenmodes are insensitive to some of these structural parameters which enable a convenient decoupling and estimation of the parameters. As a result, the method does not require complicated finite element analysis, is insensitive to the gap height and introduces no contact wear or dielectric charging effects. Experiments are performed using laser Doppler vibrometry to measure the natural frequencies of doubly clamped, nickel, RF-MEMS capacitive switches and the method is applied to extract the residual stress, beam thickness, boundary compliance and post-release curvature. (paper)

  14. Temporary clamping of bilateral external carotid arteries for surgical excision of a complex dural arteriovenous fistula

    Directory of Open Access Journals (Sweden)

    Shih-Chieh Shen

    2014-01-01

    Full Text Available Background: Some complex dural arteriovenous fistulas (DAVFs are lesions that typically have numerous arterial feeders. Surgery, including resection of fistulas or skeletonization of the diseased sinus, is still one of the important treatments for these lesions. However, major blood loss is usually encountered during craniotomy because of abundant arterial feeders from the scalp and transosseous vessels. We present a novel approach for obliteration of the fistulas with less blood loss. Methods: Our first case was a 52-year-old male who suffered from syncope and seizure. Cerebral digital subtraction angiography (DSA revealed complex DAVFs with numerous arterial feeders from bilateral external carotid arteries (ECAs and drainage into the superior sagittal sinus with cerebral venous reflux. The second case was a 48-year-old male presenting with chronic headache. His DSA also showed complex DAVFs along the superior sagittal sinus with cerebral venous reflux. In both cases, we performed the surgical procedure to obliterate the pathological fistulas after temporary clamping of bilateral ECAs and noted less blood loss than in the conventional surgery. Results: The follow-up DSA showed successful obliteration of the complex DAVFs on the first case and partial improvement on the second case followed by transarterial embolization (TAE. The symptoms of the both patients were relieved after surgery with good recovery. Conclusion: Temporary clamping of bilateral ECAs can improve the safety and ease the surgical excision for complex DAVFs. By using this technique, neurosurgeons can deal with aggressive DAVFs more confidently and calmly.

  15. A Clamped Be Window for the Dump of the HiRadMat Experiment at CERN

    CERN Document Server

    Delonca, M; Grenier, D; Maglioni, C; Sarrio Martinez, A

    2012-01-01

    At CERN, the High Radiation to Materials facility (HiRadMat) is designed to test accelerator components under the impact of high-intensity pulsed beams and will start operation in 2012. In this frame an LHC TED-type dump was installed at the end of the line, working in nitrogen over-pressure, and a 254μm-thick beryllium window was placed as barrier between the inside of the dump and the external atmosphere. Because of the special loading conditions, a clamped window design was especially developed, optimized and implemented, the more standard welded window not being suitable for such loads. Considering then the clamping force and the applied differential pressures, the stresses on the window components were carefully evaluated thanks to empirical as well as numerical models, to guarantee the structural integrity of the beryllium foil. This paper reports on choices and optimizations that led to the final design, presenting also comparative results from different solutions and the detailed results for the adop...

  16. Interleukin-2 activity can be fine tuned with engineered receptor signaling clamps.

    Science.gov (United States)

    Mitra, Suman; Ring, Aaron M; Amarnath, Shoba; Spangler, Jamie B; Li, Peng; Ju, Wei; Fischer, Suzanne; Oh, Jangsuk; Spolski, Rosanne; Weiskopf, Kipp; Kohrt, Holbrook; Foley, Jason E; Rajagopalan, Sumati; Long, Eric O; Fowler, Daniel H; Waldmann, Thomas A; Garcia, K Christopher; Leonard, Warren J

    2015-05-19

    Interleukin-2 (IL-2) regulates lymphocyte function by signaling through heterodimerization of the IL-2Rβ and γc receptor subunits. IL-2 is of considerable therapeutic interest, but harnessing its actions in a controllable manner remains a challenge. Previously, we have engineered an IL-2 "superkine" with enhanced affinity for IL-2Rβ. Here, we describe next-generation IL-2 variants that function as "receptor signaling clamps." They retained high affinity for IL-2Rβ, inhibiting binding of endogenous IL-2, but their interaction with γc was weakened, attenuating IL-2Rβ-γc heterodimerization. These IL-2 analogs acted as partial agonists and differentially affected lymphocytes poised at distinct activation thresholds. Moreover, one variant, H9-RETR, antagonized IL-2 and IL-15 better than blocking antibodies against IL-2Rα or IL-2Rβ. Furthermore, this mutein prolonged survival in a model of graft-versus-host disease and blocked spontaneous proliferation of smoldering adult T cell leukemia (ATL) T cells. This receptor-clamping approach might be a general mechanism-based strategy for engineering cytokine partial agonists for therapeutic immunomodulation. PMID:25992859

  17. A direct proofreader-clamp interaction stabilizes the Pol III replicase in the polymerization mode

    KAUST Repository

    Jergic, Slobodan

    2013-02-22

    Processive DNA synthesis by the αÉ"θ core of the Escherichia coli Pol III replicase requires it to be bound to the β 2 clamp via a site in the α polymerase subunit. How the É" proofreading exonuclease subunit influences DNA synthesis by α was not previously understood. In this work, bulk assays of DNA replication were used to uncover a non-proofreading activity of É". Combination of mutagenesis with biophysical studies and single-molecule leading-strand replication assays traced this activity to a novel β-binding site in É" that, in conjunction with the site in α, maintains a closed state of the αÉ"θ-β 2 replicase in the polymerization mode of DNA synthesis. The É"-β interaction, selected during evolution to be weak and thus suited for transient disruption to enable access of alternate polymerases and other clamp binding proteins, therefore makes an important contribution to the network of protein-protein interactions that finely tune stability of the replicase on the DNA template in its various conformational states. © 2013 European Molecular Biology Organization.

  18. Influence of non-steady state during isoglycemic hyperinsulinemic clamp in hypertension. A LIFE substudy

    DEFF Research Database (Denmark)

    Olsen, M H; Andersen, U B; Wachtell, K;

    1999-01-01

    We wanted to investigate whether time to steady state was reached within 2 h of insulin infusion during isoglycemic hyperinsulinemic clamp, comparing the glucose uptake index (M/IG) with Bergman's insulin sensitivity index (Sip). We performed a 2-h oral glucose tolerance test and a 3-h isoglycemic...... narrow limits of agreement in the patients. However, during the third hour of insulin infusion, M/IG (10.0 vs 12.21(2) x kg(-1) x min(-1) x mmol(-1), p <0.001) as well as Sip (7.1 vs 9.41(2) x kg(-1) x min(-1) x mmol(-1), p <0.001) increased significantly in the patients, but not in the healthy subjects....... Because the 2-h M/IG correlated strongly with the 3-h Sip with relatively narrow limits of agreement, it is a good measure of insulin sensitivity. However, a 2-h clamp results in lower insulin sensitivity values in elderly, hypertensive patients due to the fact that steady state is not reached...

  19. Automatic Calibration of Frequency Compensation System in Computer-Controlled Patch-Clamp Amplifier

    Directory of Open Access Journals (Sweden)

    Jun Xion

    2007-01-01

    Full Text Available Computer-controlled patch-clamp amplifier is a digitally controlled analog device used to record the cellular ion channel currents in electrophysiology research. The inherent bandwidth and performance of the headstage is limited by the stray capacitance and distributed capacitance across the feedback resistors. In order to effectively improve the performance of the headstage, the paper advanced a simplified automatic calibration method of frequency compensation system in resistor-feedback patch-clamp amplifier. The dynamic model of headstage was approximate as a two poles and one zero system in the transfer function by experience and test results, so the dynamic characteristics of the headstage were obtained employing least squares parameter estimation algorithm. Further more, the compensation parameter of high frequency booster can be estimated by the time constant of main pole of headstage. And automatic adjustment of the parameters in transient response correction stage was performed as a least squares fitting problem. The software routine running on the host computer conducted all operations of frequency compensation. Experimental results demonstrate that the simplified automatic calibration method can substantially extend the bandwidth and minimize step response error of headstage.

  20. A patch-clamp study on human sperm Cl-channel reassembled into giant liposome

    Institute of Scientific and Technical Information of China (English)

    Jun-Ping BAI; Yu-Liang SHI

    2001-01-01

    Aim: To record the single-channel currents and characterize the electrophysiological properties of the Cl-channels in human sperm membrane. Methods: The membrane proteins extracted from the human sperm were reassembled into liposome bilayer, and the liposomes were fused into giant liposomes with a diameter more than 10 μm by dehydrationrehydration procedure. The giant liposomes were used to study the Cl-channel activities by patch-clamp technique.Results: By patch clamping the giant liposome in an asymmetric NMDG (N-methyl-D-glucamine)-Cl (bath 100//pipette 200 mmol/L) solution system, three kinds of single-channel events with unit conductances of (74.1 ± 8.3) pS,( 117.0 ± 5.7) pS and ( 144.7 ±+ 4.5 ) pS, respectively, were detected. Their activities were voltage-dependent and all manner. By constructing the open and close dwell time distribution histograms and then fitting them with exponential function, two time constants were obtained in both the open and the close states. The burst activity and conductance substate of the channels were observed. Conclusion: There exist three kinds of Cl-channels with different conductance in human sperm membrane at least.

  1. Effect of organometallic clamp properties on the apparent diversity of tensile response of nanowires

    International Nuclear Information System (INIS)

    The influence of the experimental boundary conditions used for tensile testing of individual nanowires on the measured apparent mechanical response is reported. Using a microelectromechanical platform designed for in situ tensile testing, in combination with digital image correlation of sequences of scanning electron microscope images, the mechanical behavior of single crystalline Si, Pd, and Ge2Sb2Te5 nanowires was measured during load–unload cycles. In situ testing enables direct determination of the nanowire strain. Comparison of the direct strain with common metrics for apparent strain that include any compliance or slipping of the clamping materials (electron-beam induced Pt-containing deposits) highlights several different artifacts that may be manifested. Calculation of the contact stiffness is thus enabled, providing guidelines for both proper strain measurement and selection of clamping materials and geometries that facilitate elucidation of intrinsic material response. Our results suggest that the limited ability to tailor the stiffness of electron-beam induced deposits results from the predominance of the organic matrix in controlling its mechanical properties owing to relatively low Pt content and sparse morphology. (paper)

  2. Quantification of material slippage in the iliotibial tract when applying the partial plastination clamping technique.

    Science.gov (United States)

    Sichting, Freddy; Steinke, Hanno; Wagner, Martin F-X; Fritsch, Sebastian; Hädrich, Carsten; Hammer, Niels

    2015-09-01

    The objective of this study was to evaluate the potential of the partial plastination technique in minimizing material slippage and to discuss the effects on the tensile properties of thin dense connective tissue. The ends of twelve iliotibial tract samples were primed with polyurethane resin and covered by plastic plates to provide sufficient grip between the clamps. The central part of the samples remained in an anatomically unfixed condition. Strain data of twelve partially plastinated samples and ten samples in a completely anatomically unfixed state were obtained using uniaxial crosshead displacement and an optical image tracking technique. Testing of agreement between the strain data revealed ongoing but markedly reduced material slippage in partially plastinated samples compared to the unfixed samples. The mean measurement error introduced by material slippage was up to 18.0% in partially plastinated samples. These findings might complement existing data on measurement errors during material testing and highlight the importance of individual quantitative evaluation of errors that come along with self-made clamping techniques. PMID:26005842

  3. Laser microsurgery of higher plant cell walls permits patch-clamp access

    Science.gov (United States)

    Henriksen, G. H.; Taylor, A. R.; Brownlee, C.; Assmann, S. M.; Evans, M. L. (Principal Investigator)

    1996-01-01

    Plasma membranes of guard cells in epidermal peels of Vicia faba and Commelina communis can be made accessible to a patch-clamp pipet by removing a small portion (1-3 micrometers in diameter) of the guard cell wall using a microbeam of ultraviolet light generated by a nitrogen laser. Using this laser microsurgical technique, we have measured channel activity across plasma membranes of V. faba guard cells in both cell-attached and isolated patch configurations. Measurements made in the inside-out patch configuration revealed two distinct K(+)-selective channels. Major advantages of the laser microsurgical technique include the avoidance of enzymatic protoplast isolation, the ability to study cell types that have been difficult to isolate as protoplasts or for which enzymatic isolation protocols result in protoplasts not amenable to patch-clamp studies, the maintenance of positional information in single-channel measurements, reduced disruption of cell-wall-mediated signaling pathways, and the ability to investigate intercellular signaling through studies of cells remaining situated within tissue.

  4. Enhanced brain release of erythropoietin, cytokines and NO during carotid clamping.

    Science.gov (United States)

    Carelli, Stephana; Ghilardi, Giorgio; Bianciardi, Paola; Latorre, Elisa; Rubino, Federico; Bissi, Marina; Di Giulio, Anna Maria; Samaja, Michele; Gorio, Alfredo

    2016-02-01

    Although effective and safe, carotid endarterectomy (CEA) implies a reduced blood flow to the brain and likely an ischemia/reperfusion event. The high rate of uneventful outcomes associated with CEA suggests the activation of brain endogenous protection mechanisms aimed at limiting the possible ischemia/reperfusion damage. This study aims at assessing whether CEA triggers protective mechanisms such as brain release of erythropoietin and nitric oxide. CEA was performed in 12 patients; blood samples were withdrawn simultaneously from the surgically exposed ipsilateral jugular and leg veins before, during (2 and 40 min) and after clamp removal (2 min). Plasma antioxidant capacity, carbonylated proteins, erythropoietin, nitrates and nitrites (NOx) were determined. No changes in intraoperative EEG, peripheral and transcranial blood oxygen saturation were detectable, and no patients showed any neurologic sign after the intervention. Antioxidant capacity and protein carbonylation in plasma were unaffected. Differently, erythropoietin, VEGF, TNF-α and NOx increased during clamping in the jugular blood (2 and 40 min), while no changes were observed in the peripheral circulation. These results show that blood erythropoietin, VEGF, TNF-α, and NOx increased in the brain during uncomplicated CEA. This may represent an endogenous self-activated neuroprotective mechanism aimed at the prevention of ischemia/reperfusion damage. PMID:26494654

  5. Attachment ability of a clamp-bearing fish parasite, Diplozoon paradoxum (Monogenea), on gills of the common bream, Abramis brama.

    Science.gov (United States)

    Wong, Wey-Lim; Gorb, Stanislav N

    2013-08-15

    Monogeneans, which are mainly fish ectoparasites, use various types of haptoral (posterior) attachment apparatus to secure their attachment onto their hosts. However, it remains unclear how strongly a monogenean can attach onto its host. In the present study, we aimed for the first time to (1) measure pull-off forces required to detach a pair of clamp-bearing monogeneans, Diplozoon paradoxum, from gills of Abramis brama and (2) determine the contribution of muscles to the clamp movements. A mean force of 6.1±2.7 mN (~246 times the animals' weight) was required to dislodge a paired D. paradoxum vertically from the gills. There were significant differences (Pfiltered lake water (20.16±8.63 μm). This suggests that the closing of the clamps is probably not due to the continuous contraction of extrinsic muscles but is caused by the elasticity of the clamp material and that muscle activity is required for clamp opening. PMID:23580722

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

    International Nuclear Information System (INIS)

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

  7. del Nido versus St. Thomas Cardioplegia Solutions: A Single-Center Retrospective Analysis of Post Cross-Clamp Defibrillation Rates.

    Science.gov (United States)

    Buel, Shane T; Striker, Carrie Whittaker; O'Brien, James E

    2016-06-01

    There are many cardioplegia solutions currently in use for pediatric cardiopulmonary bypass (CPB). The most common being del Nido solution. Another common cardioplegia solution used for pediatric CPB is St. Thomas. In October 2014, Children's Mercy Kansas City changed from the use of modified St. Thomas to del Nido. This study compared rates of post cross-clamp fibrillation requiring defibrillation between del Nido solution and modified St. Thomas solution stratified by weight at Children's Mercy Kansas City. This retrospective study consisted of 394 patients who underwent cardiac surgery requiring cardioplegia between January 1, 2014 and July 31, 2015. The outcome measured was defibrillation upon cross-clamp removal. Statistical significance was determined using Fishers exact test with a two-sided significance level of .05. Incidence of defibrillation post cross-clamp removal was 4.4% in the del Nido group and 26.8% in the St. Thomas group (p 60-kg category had an incidence of defibrillation of 16.7% in the del Nido group and 63% in the St. Thomas group (p < .0623). This study demonstrates a 6-fold decrease in the overall rate of defibrillation post cross-clamp removal between St. Thomas and del Nido cardioplegia solutions. Analyses of weight stratifications demonstrate a decrease in the rate of defibrillation post cross-clamp removal in all categories within the del Nido group. PMID:27578896

  8. 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; Blaabjerg, Frede

    2011-01-01

    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...... configuration to approach a very low total harmonic distortion of voltage and current, which leads to the possible elimination of the output filter. Regarding the proposed configuration, a new cascade inverter is verified by cascading an asymmetrical diode-clamped inverter, in which 19 levels can be synthesized...... in output 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...

  9. Comparison: Simulation and Experimental Characterisation of an all-Optical Gain-Clamped Erbium-Doped Fibre Amplifier

    Directory of Open Access Journals (Sweden)

    T. Subramaniam M. A. Mahdi P. Poopalan, and H. Ahmad

    2012-10-01

    Full Text Available This paper presents the GC-EDFA characteristics comparison between the simulated results (using EDFA_Design software and experimental results. The comparisons reveal the usefulness of the software in simulating the behaviour of an all-optical GC-EDFA system. Comparisons are made for values obtained from the system operated at high laser power, in order to highlight the differences between the experimental and simulated values. The main objective for this comparison is to prove the capability of the software in simulating the gain-clamped system. Therefore, the software can be used to test new configurations, aimed at improvising current gain-clamped EDFA performances.Keywords optical, gain-clamping, erbium, fibre amplifier, simulation, experiment

  10. 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.

  11. Stress-stimulated current of dry rocks with constant clamping stress

    Science.gov (United States)

    Dahlgren, R. P.; Vanderbilt, V. C.; Johnston, M. J. S.

    2014-12-01

    A set of nominally dry rocks (gabbro, granite, limestone, marble, and sandstone) were subjected to asymmetric loading with a large hydraulic press. A pair of precision platens made from 1018 low carbon steel were used to apply uniaxial compressive stress (σ) to the sample, via a thin electrical insulator made from ultra-high molecular weight (UHMW) polyethylene. Self-adhesive copper electrodes were applied and burnished on the end faces and the stress-stimulated current (SSC) was monitored using a Keithley 617 instrument. A preload stress level of 5.5 MPa was applied to firmly clamp the assembly throughout the experiment. From this baseline, σ was increased to 22.25 MPa and held for 100 seconds before returning to the clamping stress level. This loading profile was repeated for four or more cycles, with a stress rate on the order of 5MPa/sec. After the first load cycle, the SSC transients (and SSV offsets) are reversible when σ returned to its baseline level. All samples showed alternating unipolar SSC transients at the beginning and end of each load cycle. SSC from limestone, Westerly granite and marble were at, or below, the measurement limit (±1 pA). All other samples except sandstone showed a negative SSC with increasing stress. For stress-stimulated voltage (SSV) there was a richer variety of transients observed such as unipolar, bipolar and more complex transient dynamics. Limestone was the only sample tested with no SSV transients although this particular rock had a major calcite inclusion in the sample. White granite tended to have the least stable SSC and SSV values. Of the six different rock samples tested under identical conditions, the SSC and SSV observed were not greater than -15 pA, presumably due to improved experimental procedures. The response for rocks with semiconductor properties (gabbro, granite) is the same as those without semiconductor properties (limestone, marble), although the values for marble were below the noise. For repetitive

  12. An Experimental Method for Measuring the Clamping Force in Double Lap Simple Bolted and Hybrid (Bolted-Bonded) Joints

    OpenAIRE

    Goldarag, Firooz Esmaeili; Barzegar, Sajjad; Babaei, Alireza

    2015-01-01

    In this research, an experimental method for measuring the clamping force as a result of tightening torque in double lap simple bolted and hybrid (bolted-bonded) joints is proposed. Two types of joints, i.e. double lap simple and hybrid (bolted-bonded) joints were prepared for testing. In order to measure the clamping force or pretension resulting from the tightening torque at different applied torques, for both types of joints, a special experimental method was designed using a steel bush th...

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

    International Nuclear Information System (INIS)

    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. (semiconductor devices)

  14. 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.

  15. Nonlinear dynamic behaviors of clamped laminated shallow shells with one-to-one internal resonance

    Science.gov (United States)

    Abe, Akira; Kobayashi, Yukinori; Yamada, Gen

    2007-07-01

    This paper investigates one-to-one internal resonance of laminated shallow shells with rigidly clamped edges. It is assumed that the natural frequencies ω2 and ω3 of two asymmetric (second and third) vibration modes have the relationship ω2≈ ω3. The displacements are expressed by using eigenvectors for linear vibration modes calculated by the Ritz method. Applying Galerkin's procedure to the equation of motion, nonlinear differential equations are derived. By considering the first vibration mode in addition to the two asymmetric vibration modes, quadratic nonlinear terms expressing the interaction between the asymmetric and the first modes appear in the differential equations. Shooting method is used to obtain the steady-state response when the driving frequency Ω is near ω2. The dynamic characteristics of the shells with the internal resonance are discussed.

  16. Fabrication and characterization of GaN nanowire doubly clamped resonators

    Science.gov (United States)

    Maliakkal, Carina B.; Mathew, John P.; Hatui, Nirupam; Rahman, A. Azizur; Deshmukh, Mandar M.; Bhattacharya, Arnab

    2015-09-01

    Gallium nitride (GaN) nanowires (NWs) have been intensely researched as building blocks for nanoscale electronic and photonic device applications; however, the mechanical properties of GaN nanostructures have not been explored in detail. The rigidity, thermal stability, and piezoelectric properties of GaN make it an interesting candidate for nano-electromechanical systems. We have fabricated doubly clamped GaN NW electromechanical resonators on sapphire using electron beam lithography and estimated the Young's modulus of GaN from resonance frequency measurements. For wires of triangular cross section with side ˜90 nm, we obtained values for the Young's modulus to be about 218 and 691 GPa, which are of the same order of magnitude as the values reported for bulk GaN. We also discuss the role of residual strain in the nanowire on the resonant frequency and the orientation dependence of the Young's modulus in wurtzite crystals.

  17. Fabrication of Si-based planar type patch clamp biosensor using silicon on insulator substrate

    International Nuclear Information System (INIS)

    The aim of this paper is to fabricate the planar type patch clamp ion-channel biosensor, which is suitable for the high throughput screening, using silicon-on-insulator (SOI) substrate. The micropore with 1.2 μm diameter is formed through the top Si layer and the SiO2 box layer of the SOI substrate by focused ion beam (FIB). Then the substrate is assembled into the microfluidic circuit. The human embryonic kidney 293 (HEK-293) cell transfected with transient receptor potential vanilloid type 1 (TRPV1) is positioned on the micropore and the whole-cell configuration is formed by the suction. Capsaicin is added to the extracellular solution as a ligand molecule, and the channel current showing the desensitization unique to TRPV1 is measured successfully

  18. Fabrication of Si-based planar type patch clamp biosensor using silicon on insulator substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.L.; Asano, T. [Graduate University for Advanced Studies, Myodaiji, Okazaki, 444-8585 (Japan); Uno, H. [Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 (Japan); Tero, R. [Graduate University for Advanced Studies, Myodaiji, Okazaki, 444-8585 (Japan); Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 (Japan); Suzui, M.; Nakao, S. [Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 (Japan); Kaito, T. [SII NanoTechnology Inc., 36-1, Takenoshita, Oyama-cho, Sunto-gun, Shizuoka, 410-1393 (Japan); Shibasaki, K.; Tominaga, M. [Okazaki Institute for Integrative Bioscience, 5-1, Higashiyama, Myodaiji, Okazaki, 444-8787 (Japan); Utsumi, Y. [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2, Koto, Kamigori, Ako-gun, Hyogo, 678-1205 (Japan); Gao, Y.L. [Department of Physics and Astronomy, Rochester University, Rochester, New York 14627 (United States); Urisu, T. [Graduate University for Advanced Studies, Myodaiji, Okazaki, 444-8585 (Japan); Institute for Molecular Science, Myodaiji, Okazaki, 444-8585 (Japan)], E-mail: urisu@ims.ac.jp

    2008-03-03

    The aim of this paper is to fabricate the planar type patch clamp ion-channel biosensor, which is suitable for the high throughput screening, using silicon-on-insulator (SOI) substrate. The micropore with 1.2 {mu}m diameter is formed through the top Si layer and the SiO{sub 2} box layer of the SOI substrate by focused ion beam (FIB). Then the substrate is assembled into the microfluidic circuit. The human embryonic kidney 293 (HEK-293) cell transfected with transient receptor potential vanilloid type 1 (TRPV1) is positioned on the micropore and the whole-cell configuration is formed by the suction. Capsaicin is added to the extracellular solution as a ligand molecule, and the channel current showing the desensitization unique to TRPV1 is measured successfully.

  19. 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.

  20. Note: Decoupling design for high frequency piezoelectric ultrasonic transducers with their clamping connections

    Energy Technology Data Exchange (ETDEWEB)

    Wang, F. J., E-mail: wangfujun@tju.edu.cn; Liang, C. M.; Tian, Y. L.; Zhao, X. Y.; Zhang, D. W. [Tianjin Key Laboratory of Equipment Design and Manufacturing Technology, School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China); Zhang, H. J. [Tianjin Key Laboratory of Modern Mechatronics Equipment Technology, School of Mechanical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

    2015-12-15

    This work presents the flexure-mechanism based decoupling design between high frequency piezoelectric ultrasonic transducers and their clamping connections to improve ultrasonic energy transmission efficiency. The ring, prismatic beam, and circular notched hinge based flanges were presented, and the crucial geometric dimensions of the transducers with the flexure decoupling flanges were determined. Finite element analysis (FEA) was carried out to investigate the dynamic characteristics of the transducers. Finally, experiments were conducted to examine and verify the effects of the proposed decoupling flanges. FEA and experimental results show that smaller frequency deviations and larger tip displacement amplitudes have been achieved by using the transducers with the flexure flanges compared with the transducer with a rigid ring-type flange, and thus the ultrasonic transmission efficiency can be improved through the flexure flanges.

  1. Nanoscale-targeted patch-clamp recordings of functional presynaptic ion channels.

    Science.gov (United States)

    Novak, Pavel; Gorelik, Julia; Vivekananda, Umesh; Shevchuk, Andrew I; Ermolyuk, Yaroslav S; Bailey, Russell J; Bushby, Andrew J; Moss, Guy W J; Rusakov, Dmitri A; Klenerman, David; Kullmann, Dimitri M; Volynski, Kirill E; Korchev, Yuri E

    2013-09-18

    Direct electrical access to presynaptic ion channels has hitherto been limited to large specialized terminals such as the calyx of Held or hippocampal mossy fiber bouton. The electrophysiology and ion-channel complement of far more abundant small synaptic terminals (≤ 1 μm) remain poorly understood. Here we report a method based on superresolution scanning ion conductance imaging of small synapses in culture at approximately 100-150 nm 3D resolution, which allows presynaptic patch-clamp recordings in all four configurations (cell-attached, inside-out, outside-out, and whole-cell). Using this technique, we report presynaptic recordings of K(+), Na(+), Cl(-), and Ca(2+) channels. This semiautomated approach allows direct investigation of the distribution and properties of presynaptic ion channels at small central synapses. PMID:24050398

  2. 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.

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

    DEFF Research Database (Denmark)

    Novak, Ivana; Hug, M.J.

    1995-01-01

    -containing solutions. Duct cells were found to have a resting membrane voltage, Vm, of-55 ± 2 mV (n = 63). An increase in the bath K+ concentration (to 19 mmol/l) or an introduction of Ba2+ (3-5 mmol/l) into the bathing solution depolarized Vm by 16 and 22 mV (n = 21; 7), respectively. Secretin (10-9 mol/l) and...... parameters, monitored with the whole-cell patch-clamp method, and those in isolated perfused ducts, monitored with the conventional microelectrodes [Novak I, Greger R: Pflügers Arch 1988;411:58-68, 546-553], are comparable. Similar conclusion can be made about the calcium measurements [Hug M, et al: Pflügers...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    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......This paper proposes a new single stage buck-boost DC-AC neutral point clamped inverter topology which integrates the cascaded configurations of recently introduced inductor-capacitor-capacitor-transformer impedance source network (by Adamowicz) and classic NPC configuration. As a consequence, it...... has enhanced buck-boost functionality and low output voltage distortions compared to the traditional Z-source inverter; it has continuous input current which reduces the source stress and inverter noise; it also contains two built-in capacitors which can block the DC current in the transformer...

  6. Pulse-Width-Modulation of Neutral-Point-Clamped Sparse Matrix Converter

    DEFF Research Database (Denmark)

    Loh, P.C.; Blaabjerg, Frede; Gao, F.;

    2007-01-01

    Sparse matrix converter is an alternative "allsemiconductor" energy processor proposed recently for converting an ac source with fixed magnitude and frequency to a variable voltage and frequency supply that can meet the requirements of a particular industry application. In principle, sparse matrix...... input current and output voltage can be achieved with minimized rectification switching loss, rendering the sparse matrix converter as a competitive choice for interfacing the utility grid to (e.g.) defense facilities that require a different frequency supply. As an improvement, sparse matrix converter...... literature. Addressing the afore-described issues, this paper focuses on the operational mode analysis of a three-level sparse 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...

  7. 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...

  8. Ultra-coherent nanomechanical resonators via soft clamping and dissipation dilution

    CERN Document Server

    Tsaturyan, Yeghishe; Polzik, Eugene S; Schliesser, Albert

    2016-01-01

    The small mass and high coherence of nanomechanical resonators render them the ultimate force probe, with applications ranging from biosensing and magnetic resonance force microscopy, to quantum optomechanics. A notorious challenge in these experiments is thermomechanical noise related to dissipation through internal or external loss channels. Here, we introduce a novel approach to defining nanomechanical modes, which simultaneously provides strong spatial confinement, full isolation from the substrate, and dilution of the resonator material's intrinsic dissipation by five orders of magnitude. It is based on a phononic bandgap structure that localises the mode, without imposing the boundary conditions of a rigid clamp. The reduced curvature in the highly tensioned silicon nitride resonator enables mechanical $Q>10^{8}$ at $ 1 \\,\\mathrm{MHz}$, yielding the highest mechanical $Qf$-products ($>10^{14}\\,\\mathrm{Hz}$) yet reported at room temperature. The corresponding coherence times approach those of optically t...

  9. 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.

  10. Influence of pipe wall effects on clamp-on ultrasonic flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Funck, B.; Mitzkus, A. [Flexim GmbH, Berlin (Germany); Panicke, M.; Specht, O.; Fiedler, O. [Flexim GmbH, Berlin (Germany)]|[Rostock Univ. (Germany). FB Elektrotechnik

    2001-07-01

    Clamp-on ultrasonic flowmeters enable the noninvasive measurement of flow in pipes. The transducers are coupled to the pipe wall and cover a wide range of rated inside diameters when suitably dimensioned. The transit time technique is applicable at sufficiently pure fluids. The time difference of contrapropagating signals is related to the velocity of flow on the path defined by the transducers. The Doppler method utilizes the signals scattered by particles or bubbles. The calibration factor depends on the size and position of the volume determined by the intersection of the transducer beams. The paper reports on effects of the pipe wall on both the transit time technique and the Doppler method of flow measurement. The sound propagation between the transducer is described by acoustic transfer functions. (orig.)

  11. Multifrequency excitation of a clamped–clamped microbeam: Analytical and experimental investigation

    KAUST Repository

    Jaber, Nizar

    2016-03-14

    Using partial electrodes and a multifrequency electrical source, we present a large-bandwidth, large-amplitude clamped–clamped microbeam resonator excited near the higher order modes of vibration. We analytically and experimentally investigate the nonlinear dynamics of the microbeam under a two-source harmonic excitation. The first-frequency source is swept around the first three modes of vibration, whereas the second source frequency remains fixed. New additive and subtractive resonances are demonstrated. We illustrated that by properly tuning the frequency and amplitude of the excitation force, the frequency bandwidth of the resonator is controlled. The microbeam is fabricated using polyimide as a structural layer coated with nickel from the top and chromium and gold layers from the bottom. Using the Galerkin method, a reduced order model is derived to simulate the static and dynamic response of the device. A good agreement between the theoretical and experimental data are reported.

  12. Calculation Method for Flight Limit Load of V-band Clamp Separation Shock

    Science.gov (United States)

    Iwasa, Takashi; Shi, Qinzhong

    A simplified calculation method for estimating a flight limit load of the V-band clamp separation shock was established. With this method, the flight limit load is estimated through addition of an appropriate envelope margin to the results acquired with the simplified analysis method proposed in our previous paper. The envelope margin used in the method was calculated based on the reviews on the differences observed between the results of a pyroshock test and the analysis. Using the derived envelope margin, a calculating formula of the flight limit load, which envelopes the actual pyroshock responses with a certain probability, was developed. Based on the formula, flight limit loads for several actual satellites were estimated and compared to the test results. The comparative results showed that the estimated flight limit loads appropriately envelope the test results, which confirmed the effectiveness of the proposed method.

  13. Model Predictive Control of Z-source Neutral Point Clamped Inverter

    DEFF Research Database (Denmark)

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

    2011-01-01

    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......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...... 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...

  14. 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 effic...... 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.......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...

  15. 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%.

  16. The strain dependence of the transport current characteristics in Bi-2223 silver clamped thick film

    International Nuclear Information System (INIS)

    The dependences of stress on strain, strain on the critical current density, and the relation of Jc(H) at several strains were measured in Bi-2223 silver clamped thick film. The results indicate that the stress-strain curve has two strain transitions which are respectively correspond to the beginning and ending of breaking in Bi1.8Pb0.4Sr2Ca2Cu3Oy thick film. At ΔX/X≤2.5%, the critical current density Jc decreases slowly with ΔX/X increasing. At ΔX/X≥2.5%, Jc decreases rapidly with ΔX/X increasing. As strain increases, the characteristics of Jc(H) decrease rapidly and the weak link junctions emerges obviously. The microstructures show that the decrease of Jc and the variance of characteristics of Jc(H) relate to the breaking of intergrain and grains in the thick film

  17. The fluorescent detection of Paradiplozoon sp. (Monogenea: Diplozoidae attachment clamps' sclerites and integumental proteins : research communication

    Directory of Open Access Journals (Sweden)

    S.J. Milne

    2006-09-01

    Full Text Available In the genus Paradiplozoon, few hard structures are present therefore most of the taxonomic studies have focused on the unique ultrastructure of the sclerites. Alcohol-fixed specimens were transferred to BSA-saline for 5 min. before staining indefinitely with 5 µl WGA-TRX, 5 µl SYTO 9 and 5 µl of Cal co fluor White M2R. Rhodamine, Fluorescein and DAPI bandpass filters on the microscope enabled selective light wavelength illumination of the three flourochromes by a mercury light source. This method provided an easy and rapid methodology to show the internal sclerites of attachment clamps. It is suitable for alcohol preserved specimens and may have additional applications in other helminth organisms.

  18. Palaeoclimate Interpretation at the Locality Velka Causa (Early Miocene, Western Carpathians) based on CLAMP Method

    International Nuclear Information System (INIS)

    Palaeontological locality Velka Causa is situated in the Handlova-Novaky brown-coal basin (Upper Nitra depression) about 3 km north of Velka Causa in an outcrop exposed by a stream flowing through the village of Mala Causa. Studied palaeobotanical material, stored in the Hornonitrianske museum in Prievidza, is fossilized in light-gray clays of Eggenburgian age proved by occurrence of molluscs, foraminifers and ostracods. Sediments were laid down in a sea gulf formed during an Eggenburgian transgression. Plant imprints belong to plants which grew near the sea shore and on the slopes of adjacent mountains. Only dicots were chosen from all fossil leaves occurred in the studied collection. They were sorted into morpho-species and were examined for the presence or absence of each of the 31 morphological characters used after CLAMP categorization. A total of 246 fossil samples were studied. Vegetation used in the dataset for this study indicates subtropical climate.

  19. 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.

  20. Room temperature, very sensitive thermometer using a doubly clamped microelectromechanical beam resonator for bolometer applications

    Science.gov (United States)

    Zhang, Y.; Watanabe, Y.; Hosono, S.; Nagai, N.; Hirakawa, K.

    2016-04-01

    We propose a room temperature, all electrical driving and detecting, very sensitive thermometer structure using a microelectromechanical (MEMS) resonator for bolometer applications. We have fabricated a GaAs doubly clamped MEMS beam resonator whose oscillation can be excited and detected by the piezoelectric effect. When a heating power is applied to a NiCr film deposited on the MEMS beam surface, internal thermal stress is generated in the beam, leading to a reduction in the resonance frequency. The present device detects the shift in the resonance frequency caused by heating and works as a very sensitive thermometer. When the resonator was driven by a voltage slightly below the threshold for the nonlinear, hysteretic oscillation, the thermometer showed a voltage responsivity of about 3300 V/W, while keeping a low noise spectral density of about 60 nV/Hz1/2, demonstrating a noise equivalent power of bolometers for room-temperature operation.

  1. Characterization of a patch-clamp microchannel array towards neuronal networks analysis

    DEFF Research Database (Denmark)

    Alberti, Massimo; Snakenborg, Detlef; Lopacinska, Joanna M.;

    2010-01-01

    simultaneous patch clamping of cultured cells or neurons in the same network. A disposable silicon/silicon dioxide (Si/SiO2) chip with a microhole array was integrated in a microfluidic system for cell handling, perfusion and electrical recording. Fluidic characterization showed that our PC mu CA can work as a...... theory, but the capacitance is still too high for high resolution recording. The system was tested on HeLa cells: successful cell trapping with a sealing of 40 M Omega was recorded. Modification of the Si/SiO2 chip is needed in order to achieve a better sealing and long-term cell culturing in the PC mu...

  2. Five-Level Z-Source Neutral Point-Clamped Inverter

    DEFF Research Database (Denmark)

    Gao, F.; Loh, P.C.; Blaabjerg, Frede;

    2007-01-01

    This paper proposes a five-level Z-source neutralpoint- clamped (NPC) inverter with two Z-source networks functioning as intermediate energy storages coupled between dc sources and NPC inverter circuitry. Analyzing the operational principles of Z-source network with partial dclink shoot......-through scheme reveals the hidden theories in the five-level Z-source NPC inverter unlike the operational principle appeared in the general two-level Z-source inverter, so that the five-level Z-source NPC inverter can be designed with the modulation of carrier-based phase disposition (PD) or alternative phase...... opposite disposition (APOD) technique. To verify the theoretical findings and practical issues, a scaled down laboratory prototype was constructed and tested with a 1.3 kw induction motor load....

  3. Gel chromatography of immunoextracted plasma calcitonin in response to the calcium clamp in healthy males

    International Nuclear Information System (INIS)

    A radioimmunoassay (RIA) was developed for immunoreactive calcitonin (iCT) in human plasma. Antibodies against synthetic human calcitonin (hCT) coupled to bovine serum albumin (BSA) were raised in rabbits and were directed against the carboxy terminal part of CT. The detection limit of the assay was 8 pg/ml. In 7 males the iCT response to a calcium-clamp was studied. Blood was collected at 0,30 and 60 min after the start of the calcium infusion. iCT was measured directly in plasma and in extracts obtained after purification of plasma iCT by means of immobilized CT antiboides. There was a good correlation between iCT in plasma samples and extracts, r = 0.993, n = 14 (P< 0.001). Dilution curves of extracts and plasma were parallel with the hCT standard curves. Gel chromatography of the extracts on Sephadex G-50 and G-75 disclosed heterogeneity of iCT in normal plasma during basal conditions as well as during calcium stimulation. Thirty min after the start of the calcium clamp all molecular forms, most likely constituting monomeric and dimeric CT and larger forms, were increased, while after 60 min iCT seemed to constitute predominantly forms larger than monomeric TCY. Basal levels of unextracted iCT in healthy males (n = 44, 37 +/- 10 years) were 15 +/- 9 pg-equivalents/ml (mean +/- SD), which was higher than in females (n = 40, 32 +/- 9 years) 11 +/- 4 pg-equivalents/ml (P < 0.05). (author)

  4. Management of open olecranon fractures using clamp-cum-compressor device

    Directory of Open Access Journals (Sweden)

    Kundu Zile

    2009-01-01

    Full Text Available Background: Open fractures of olecranon are not a rare occurrence in patients with road traffic accidents particularly motor bike riders who don′t use elbow guards. Definitive treatment has to be delayed in many till the wound heals. The present study was conducted to evaluate the results of open fractures of olecranon using clamp-cum-compressor device. Materials and Methods: Seventeen patients between the ages of 20 and 45 years of open olecranon fractures reported 5-20 days after injury were treated using an indigenous clamp-cum-compressor. All fractures were Mayo type II-A, i.e., displaced, stable and noncomminuted. Four patients had Gustilo-Anderson grade I and 13 had Gustilo-Anderson grade II open fractures. The patients with transverse or short oblique fractures were included in the study. The apparatus was applied under regional anesthesia after thorough washing and debridement of wounds with few loose sutures applied wherever needed. The wounds healed within 2-4 weeks and fractures united within 8-10 weeks. The elbow was mobilized with apparatus still in place. The results were evaluated by MayoElbow performance score. Results: We achieved excellent results in twelve patients, good in four and poor in one patient, who reported late, hooks of the apparatus were cut through the proximal fragment, leading to union of fracture in elongation and restricted elbow movements. Conclusion: The apparatus was found to be quite useful in transverse and short oblique fractures with contamination or infection, where internal fixation has to be delayed or avoided.

  5. Dynamic response of a clamped/free hollow circular cylinder under travelling torsional impact loads

    International Nuclear Information System (INIS)

    Impact-induced vibrations in the casing of a gas centriguge due to a sudden failure of the spinning rotor (crash) can cause structural disintegrity of the casing. In order to study the influence of the rotor failure bahaviour and the impact load histories on the dynamic response of the casing, a simple crash model is proposed in this paper to analyse the transient torsional response due to tangential components of the impact loads. The casing is modeled as a linear-elastic hollow circular cylinder, clamped at the lower end and free at the upper end. The rotor is thought to breakup in identical sections in a sequence determined by its fracture behaviour. Each section is assumed to cause an axi-symmetric load distribution at the inner surface of the casing. Therefore the problem is essentially reduced to the analysis of a clamped/free cylinder under travelling torsional impact loads. The problem is solved by representing the impact loads as local pulses acting over the length of the sections. A perturbation method is used to show that the general two-dimensional theory of axi-symmetric torsional wave propagation in circular cylinders, for the problem under consideration, may be approximated by the elementary one-dimensional theory. Solutions are obtained according to the usual modal expansion approach. Measurements of transient torsional responses are shown to be in good agreement with the calculated responses by choosing a suitable shape of the pulses. The effects of travelling velocity and pulse shape are investigated. Finally the transfer of kinetic energy in the rotor to vibrational energy of torsion in the casing is studied. (orig.)

  6. MATLAB-based automated patch-clamp system for awake behaving mice.

    Science.gov (United States)

    Desai, Niraj S; Siegel, Jennifer J; Taylor, William; Chitwood, Raymond A; Johnston, Daniel

    2015-08-01

    Automation has been an important part of biomedical research for decades, and the use of automated and robotic systems is now standard for such tasks as DNA sequencing, microfluidics, and high-throughput screening. Recently, Kodandaramaiah and colleagues (Nat Methods 9: 585-587, 2012) demonstrated, using anesthetized animals, the feasibility of automating blind patch-clamp recordings in vivo. Blind patch is a good target for automation because it is a complex yet highly stereotyped process that revolves around analysis of a single signal (electrode impedance) and movement along a single axis. Here, we introduce an automated system for blind patch-clamp recordings from awake, head-fixed mice running on a wheel. In its design, we were guided by 3 requirements: easy-to-use and easy-to-modify software; seamless integration of behavioral equipment; and efficient use of time. The resulting system employs equipment that is standard for patch recording rigs, moderately priced, or simple to make. It is written entirely in MATLAB, a programming environment that has an enormous user base in the neuroscience community and many available resources for analysis and instrument control. Using this system, we obtained 19 whole cell patch recordings from neurons in the prefrontal cortex of awake mice, aged 8-9 wk. Successful recordings had series resistances that averaged 52 ± 4 MΩ and required 5.7 ± 0.6 attempts to obtain. These numbers are comparable with those of experienced electrophysiologists working manually, and this system, written in a simple and familiar language, will be useful to many cellular electrophysiologists who wish to study awake behaving mice. PMID:26084901

  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...

  8. 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...

  9. 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.

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

    OpenAIRE

    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.

  11. Asystole to cross-clamp period predicts development of biliary complications in liver transplantation using donation after cardiac death donors.

    Science.gov (United States)

    Taner, C Burcin; Bulatao, Ilynn G; Perry, Dana K; Sibulesky, Lena; Willingham, Darrin L; Kramer, David J; Nguyen, Justin H

    2012-08-01

    This study sought to determine the procurement factors that lead to development of intrahepatic bile duct strictures (ITBS) and overall biliary complications in recipients of donation after cardiac death (DCD) liver grafts. Detailed information for different time points during procurement (withdrawal of support; SBP mandatory wait period; asystole; incision; aortic cross clamp) and their association with the development of ITBS and overall biliary complications were examined using logistic regression. Two hundred and fifteen liver transplants using DCD donors were performed between 1998 and 2010 at Mayo Clinic Florida. Of all the time periods during procurement, only asystole-cross clamp period was significantly different between patients with ITBS versus no ITBS (P = 0.048) and between the patients who had overall biliary complications versus no biliary complications (P = 0.047). On multivariate analysis, only asystole-cross clamp period was significant predictor for development of ITBS (P = 0.015) and development of overall biliary complications (P = 0.029). Hemodynamic changes in the agonal period did not emerge as risk factors. The results of the study raise the possibility of utilizing asystole-cross-clamp period in place of or in conjunction with donor warm ischemia time in determining viability or quality of liver grafts. PMID:22703372

  12. 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.

  13. Structure of p15PAF-PCNA complex and implications for clamp sliding during DNA replication and repair

    DEFF Research Database (Denmark)

    De Biasio, Alfredo; de Opakua, Alain Ibáñez; Mortuza, Gulnahar B;

    2015-01-01

    The intrinsically disordered protein p15(PAF) regulates DNA replication and repair by binding to the proliferating cell nuclear antigen (PCNA) sliding clamp. We present the structure of the human p15(PAF)-PCNA complex. Crystallography and NMR show the central PCNA-interacting protein motif (PIP...

  14. Late umbilical cord-clamping as an intervention for reducing iron deficiency anaemia in term infants in developing and industrialised countries : a systematic review

    NARCIS (Netherlands)

    van Rheenen, Patrick; Brabin, Bernard J

    2004-01-01

    This review evaluates the potential of delayed cord-clamping for improving iron status and reducing anaemia in term infants and for increasing the risk of polycythaemia and hyperbilirubinaemia. We applied a strict search protocol to identify controlled trials of early vs late cord-clamping. Four tri

  15. 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)

  16. 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

  17. Classical and numerical approaches to determining V-section band clamp axial stiffness

    Science.gov (United States)

    Barrans, Simon M.; Khodabakhshi, Goodarz; Muller, Matthias

    2014-12-01

    V-band clamp joints are used in a wide range of applications to connect circular flanges, for ducts, pipes and the turbocharger housing. Previous studies and research on V-bands are either purely empirical or analytical with limited applicability on the variety of V-band design and working conditions. In this paper models of the V-band are developed based on the classical theory of solid mechanics and the finite element method to study the behaviour of theV-bands under axial loading conditions. The good agreement between results from the developed FEA and the classical model support the suitability of the latter to modelV-band joints with diameters greater than 110mm under axial loading. The results from both models suggest that the axial stiffness for thisV-band cross section reaches a peak value for V-bands with radius of approximately 150 mmacross a wide range of coefficients of friction. Also, it is shown that the coefficient of friction and the wedge angle have a significant effect on the axial stiffness of V-bands.

  18. Fabrication and characterization of GaN nanowire doubly clamped resonators

    Energy Technology Data Exchange (ETDEWEB)

    Maliakkal, Carina B., E-mail: carina@tifr.res.in; Mathew, John P.; Hatui, Nirupam; Rahman, A. Azizur; Deshmukh, Mandar M.; Bhattacharya, Arnab [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2015-09-21

    Gallium nitride (GaN) nanowires (NWs) have been intensely researched as building blocks for nanoscale electronic and photonic device applications; however, the mechanical properties of GaN nanostructures have not been explored in detail. The rigidity, thermal stability, and piezoelectric properties of GaN make it an interesting candidate for nano-electromechanical systems. We have fabricated doubly clamped GaN NW electromechanical resonators on sapphire using electron beam lithography and estimated the Young's modulus of GaN from resonance frequency measurements. For wires of triangular cross section with side ∼90 nm, we obtained values for the Young's modulus to be about 218 and 691 GPa, which are of the same order of magnitude as the values reported for bulk GaN. We also discuss the role of residual strain in the nanowire on the resonant frequency and the orientation dependence of the Young's modulus in wurtzite crystals.

  19. Requirements to gap widths and clamping for CO2 laser butt welding

    DEFF Research Database (Denmark)

    Gong, Hui; Juhl, Thomas Winther

    1999-01-01

    In the experimental study of fixturing and gap width requirements a clamping device for laser butt welding of steel sheets has been developed and tested. It has fulfilled the work and made the gap width experiments possible.It has shown that the maximum allowable gap width to some extent is...... inversely related to the welding speed. Also larger laser power leads to bigger allowable gap widths. The focal point position, though, has little influence on the maximum allowable gap width.During analysis X-ray photos show no interior porosity in the weld seam. Other methods have been applied to measure...... responses from variations in welding parameters.The table below lists the results of the study, showing the maximum allowable gap widths and some corresponding welding parameters.Maximum allowable Gap Width; Welding Speed; Laser Power:0.10 mm2 m/min2, 2.6 kW0.15 mm1 m/min2 kW0.20 mm1 m/min2.6 kW0.30 mm0.5 m...

  20. 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.

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

    Science.gov (United States)

    Alcheikh, N.; Kosuru, L.; Jaber, N.; Bellaredj, M.; Younis, M. I.

    2016-06-01

    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.

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

    International Nuclear Information System (INIS)

    In this study, we demonstrate analytically and experimentally the excitations of the higher order modes of vibrations in electrostatically actuated clamped–clamped microbeam resonators. The concept is based on using partial electrodes with shapes that induce strong excitation of the mode of interest. The devices are fabricated using polyimide as a structural layer coated with nickel from the top and chrome and gold layers from the bottom. Experimentally, frequency sweeps with different electro-dynamical loading conditions are shown to demonstrate the excitation of the higher order modes of vibration. Using a half electrode, the second mode is excited with high amplitude of vibration compared with almost zero response using the full electrode. Also, using a two-third electrode configuration is shown to amplify the third mode resonance amplitude compared with the full electrode under the same electrical loading conditions. An analytical model is developed based on the Euler–Bernollui beam model and the Galerkin method to simulate the device response. Good agreement between the simulation results and the experimental data is reported. (paper)

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

    Directory of Open Access Journals (Sweden)

    Sanjoy Das Neogi

    2013-01-01

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

  4. Analysis of subsynchronous resonance with 5 level diode-clamped VSI based SSSC

    Energy Technology Data Exchange (ETDEWEB)

    Pillai, G.N.; Gupta, H.O. [Indian Inst. of Technology, Roorkee (India). Dept. of Electrical Engineering

    2005-07-01

    Series capacitors are often used in long transmission lines to increase power transfer capability and improve transient stability. This paper presented an analysis of a series compensated power system with a static synchronous series compensator (SSSC). The aim of the study was to investigate the subsynchronous resonance (SSR) characteristics of the system. A 5-level diode clamped voltage source inverter (VSI) with fundamental frequency switching was applied. SSR characteristics were investigated using an eigenvalue analysis technique. The interactions between the compensated network and the generator were examined using the IEEE SSR benchmark system. The system was characterized by 4 unstable torsional modes. A control loop was incorporated in order to understand the behaviour of the overall system, and 2 steady-state operating points were selected. Results of the study showed that torsional or subsynchronous modes can become unstable when parameters of the controllers are not properly considered. It was concluded that the SSSC was capable of damping out the torsional oscillations of the systems. 12 refs., 1 tab., 6 figs.

  5. Active vibration control of clamped beams using positive position feedback controllers with moment pair

    International Nuclear Information System (INIS)

    This paper investigates the active vibration control of clamp beams using positive position feedback (PPF) controllers with a sensor/ moment pair actuator. The sensor/moment pair actuator which is the non-collocated configuration leads to instability of the control system when using the direct velocity feedback (DVFB) control. To alleviate the instability problem, a PPF controller is considered in this paper. A parametric study of the control system with PPF controller is first conducted to characterize the effects of the design parameters (gain and damping ratio in this paper) on the stability and performance. The gain of the controller is found to affect only the relative stability. Increasing the damping ratio of the controller slightly improves the stability condition while the performance gets worse. In addition, the higher mode tuned PPF controller affects the system response at the lower modes significantly. Based on the characteristics of PPF controllers, a multi-mode controllable SISO PPF controller is then considered and tuned to different modes (in this case, three lowest modes) numerically and experimentally. The multi-mode PPF controller can be achieved to have a high gain margin. Moreover, it reduces the vibration of the beam significantly. The vibration levels at the tuned modes are reduced by about 11 dB

  6. A clamp-on ultrasonic cross correlation flow meter for one-phase flow

    Science.gov (United States)

    Worch, A.

    1998-04-01

    The correlation technique presented offers a good possibility for measuring the average rate of flow of fluids through pipes. The only physical parameter required for the measurement principle is the well known distance between the sensors. The new system presented consists of ultrasonic sensors, transforming the natural, stochastic fluctuations of velocity, pressure and density into two signals with a delay time T, and a real-time correlator, extracting the delay time from the signals and calculating the average rate of flow of the fluid. In contrast to established flow measuring methods, no bluff bodies are necessary and electrical conductivity of the fluid is not required. In contrast to time-of-flight flow meters, a small amount of air bubbles or particles causes no signal losses and does not interrupt the measurement process. In this paper a detailed theoretical signal model describing the interaction of sound waves in random continuum and turbulent media will be presented. With this model the phase modulation of the ultrasonic waves and systematic errors can be described and some design parameters can be optimized. Measurements have been carried out with 40 and 50 mm pipe diameters for direct fluid contact and clamp-on transducers. The measurement error of the new flow meter has been found to be less than 2% from the reference value for a Reynolds number range 25 000-250 000 and, even down to a Reynolds number of 4000, it has been found to be less than 3%.

  7. Fabrication and characterization of GaN nanowire doubly clamped resonators

    International Nuclear Information System (INIS)

    Gallium nitride (GaN) nanowires (NWs) have been intensely researched as building blocks for nanoscale electronic and photonic device applications; however, the mechanical properties of GaN nanostructures have not been explored in detail. The rigidity, thermal stability, and piezoelectric properties of GaN make it an interesting candidate for nano-electromechanical systems. We have fabricated doubly clamped GaN NW electromechanical resonators on sapphire using electron beam lithography and estimated the Young's modulus of GaN from resonance frequency measurements. For wires of triangular cross section with side ∼90 nm, we obtained values for the Young's modulus to be about 218 and 691 GPa, which are of the same order of magnitude as the values reported for bulk GaN. We also discuss the role of residual strain in the nanowire on the resonant frequency and the orientation dependence of the Young's modulus in wurtzite crystals

  8. High quality cord blood banking is feasible with delayed clamping practices. The eight-year experience and current status of the national Swedish Cord Blood Bank.

    Science.gov (United States)

    Frändberg, Sofia; Waldner, Berit; Konar, Jan; Rydberg, Lennart; Fasth, Anders; Holgersson, Jan

    2016-09-01

    The National Swedish Cord Blood Bank (NS-CBB) is altruistic and publicly funded. Herein we describe the status of the bank and the impact of delayed versus early clamping on cell number and volume. Cord Blood Units (CBUs) were collected at two University Hospitals in Sweden. Collected volume and nucleated cell content (TNC) were investigated in 146 consecutive Cord Blood (CB) collections sampled during the first quarter of 2012 and in 162 consecutive CB collections done in the first quarter of 2013, before and after clamping practices were changed from immediate to late (60 s) clamping. NS-CBB now holds close to 5000 units whereof 30 % are from non-Caucasian or mixed origins. Delayed clamping had no major effect on collection efficiency. The volume collected was slightly reduced (mean difference, 8.1 ml; 95 % CI, 1.3-15.0 ml; p = 0.02), while cell recovery was not (p = 0.1). The proportion of CBUs that met initial total TNC banking criteria was 60 % using a TNC threshold of 12.5 × 10(8), and 47 % using a threshold of 15 × 10(8) for the early clamping group and 52 and 37 % in the late clamping group. Following implementation of delayed clamping practices at NS-CBB; close to 40 % of the collections in the late clamping group still met the high TNC banking threshold and were eligible for banking, implicating that that cord blood banking is feasible with delayed clamping practices. PMID:27342904

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

    Directory of Open Access Journals (Sweden)

    Anton Chizhov

    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.

  10. Fatigue Property of Open-Hole Steel Plates Influenced by Bolted Clamp-up and Hole Fabrication Methods

    Directory of Open Access Journals (Sweden)

    Zhi-Yu Wang

    2016-08-01

    Full Text Available Steel plates with open holes are commonly used in structural assemblies. The fatigue properties of such details are influenced by bolted clamp-up and hole fabrication methods. The fracture surface, stiffness degradation and fatigue life of test specimens are investigated in detail and compared with the contemporary test data. The analysis results show that the presence of draglines greatly influences the fatigue crack initiation at the open-hole cut by laser. The bolted clamp-up condition greatly enhances the stiffness and the fatigue life of the open-hole details. A discussion is also made from a comparison with the referred fatigue life of hole fabrication details, such as the influence of plate thickness and plasma cutting, drilling and oxy-fuel gas cutting, with the details studied herein. This work could enhance the understanding of the fatigue property and design of such details.

  11. IMPROVE THE KINETIC PERFORMANCE OF THE PUMP CONTROLLED CLAMPING UNIT IN PLASTIC INJECTION MOLDING MACHINE WITH ADAPTIVE CONTROL STRATEGY

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The kinetic characteristics of the clamping unit of plastic injection molding machine that is controlled by close loop with newly developed double speed variable pump unit are investigated.Considering the wide variation of the cylinder equivalent mass caused by the transmission ratio of clamping unit and the severe instantaneous impact force acted on the cylinder during the mold closing and opening process, an adaptive control principle of parameter and structure is proposed to improve its kinetic performance. The adaptive correlation between the acceleration feedback gain and the variable mass is derived. The pressure differential feedback is introduced to improve the dynamic performance in the case of small inertia and heavy impact load. The adaptation of sum pressure to load is used to reduce the energy loss of the system. The research results are verified by the simulation and experiment. The investigation method and the conclusions are also suitable for the differential cylinder system controlled by the traditional servo pump unit.

  12. A propagation time difference evaluation for a clamp-on ultrasonic flowmeter for low-pressure gas

    Science.gov (United States)

    Nishiguchi, Hiroshi; Sawayama, Toshiyuki; Nagamune, Kouki

    2016-07-01

    We have been studying the development of a clamp-on ultrasonic flowmeter for measuring the gas flow rate, especially at low-pressure gas such as atmospheric pressure. In this study, we evaluated the propagation time difference of ultrasonic wave for measuring the airflow at atmospheric pressure. We placed a pair of ultrasonic transducers outside a pipe and generated ultrasonic waves aslant to the flow direction. We observed the propagation time difference of the ultrasonic wave as a function of the gas flow velocity, and found that the difference was proportional to the gas flow. Therefore, it was shown that we were able to measure the atmospheric pressure gas flow rate with a clamp-on ultrasonic flowmeter. Moreover, we evaluated the dependency of ultrasonic wave intensity on gas pressure.

  13. Retained Intra-Abdominal Surgical Clamp Complicating Emergency Laparotomy: Incidental Finding on Hysterosalpingogram for Evaluation of Tubal Infertility

    Directory of Open Access Journals (Sweden)

    Adebiyi Gbadebo Adesiyun

    2014-01-01

    Full Text Available The finding of intraperitoneal foreign body complicating surgical intervention broadly remains as an issue of safety in the operative room, a source of emotive concern for the patient, and an upsetting but equally embarrassing situation to the surgeon and the team. However, in the media world, it is a source of sumptuous and captivating headline on the newspaper and to the legal profession, an attractive case to prosecute. A middle age teacher presented with secondary infertility. She had emergency laparotomy fifteen years ago for ruptured tubal ectopic pregnancy in a private hospital and postoperative period was uneventful. Amongst other investigations to find out the cause of infertility, she had hysterosalpingography and a radio-opaque clamp was visualized on the films. She was counselled and had laparotomy. A pair of surgical Kocher clamps was retrieved buried in the mesentery.

  14. 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.

  15. Comparative Study through Modal Analysis of Thin Trapeze Shape Plates Clamped on Contour without and with Damages

    Directory of Open Access Journals (Sweden)

    Cornel Hatiegan

    2015-09-01

    Full Text Available This paper presents a comparative study of four types of plates in the form of trapeze, clamped on the contour, regarding modal analysis. After this analysis, there have been obtained the Eigen frequencies for 30 vibration modes between the limits 183.37 ÷ 1206.3 [Hz]. For these results there has been computed the absolute variation, respectively the relative frequency shifts of the analyzed plates.

  16. 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.

  17. Voltage Clamp Fluorimetry Reveals a Novel Outer Pore Instability in a Mammalian Voltage-gated Potassium Channel

    OpenAIRE

    Vaid, Moninder; Claydon, Thomas W.; Rezazadeh, Saman; Fedida, David

    2008-01-01

    Voltage-gated potassium (Kv) channel gating involves complex structural rearrangements that regulate the ability of channels to conduct K+ ions. Fluorescence-based approaches provide a powerful technique to directly report structural dynamics underlying these gating processes in Shaker Kv channels. Here, we apply voltage clamp fluorimetry, for the first time, to study voltage sensor motions in mammalian Kv1.5 channels. Despite the homology between Kv1.5 and the Shaker channel, attaching TMRM ...

  18. Vascular relaxation of canine visceral arteries after ischemia by means of supraceliac aortic cross-clamping followed by reperfusion

    Directory of Open Access Journals (Sweden)

    Dalio Marcelo B

    2010-07-01

    Full Text Available Abstract Background The supraceliac aortic cross-clamping can be an option to save patients with hipovolemic shock due to abdominal trauma. However, this maneuver is associated with ischemia/reperfusion (I/R injury strongly related to oxidative stress and reduction of nitric oxide bioavailability. Moreover, several studies demonstrated impairment in relaxation after I/R, but the time course of I/R necessary to induce vascular dysfunction is still controversial. We investigated whether 60 minutes of ischemia followed by 30 minutes of reperfusion do not change the relaxation of visceral arteries nor the plasma and renal levels of malondialdehyde (MDA and nitrite plus nitrate (NOx. Methods Male mongrel dogs (n = 27 were randomly allocated in one of the three groups: sham (no clamping, n = 9, ischemia (supraceliac aortic cross-clamping for 60 minutes, n = 9, and I/R (60 minutes of ischemia followed by reperfusion for 30 minutes, n = 9. Relaxation of visceral arteries (celiac trunk, renal and superior mesenteric arteries was studied in organ chambers. MDA and NOx concentrations were determined using a commercially available kit and an ozone-based chemiluminescence assay, respectively. Results Both acetylcholine and calcium ionophore caused relaxation in endothelium-intact rings and no statistical differences were observed among the three groups. Sodium nitroprusside promoted relaxation in endothelium-denuded rings, and there were no inter-group statistical differences. Both plasma and renal concentrations of MDA and NOx showed no significant difference among the groups. Conclusion Supraceliac aortic cross-clamping for 60 minutes alone and followed by 30 minutes of reperfusion did not impair relaxation of canine visceral arteries nor evoke biochemical alterations in plasma or renal tissue.

  19. Carrier-based PWM strategies for the comprehensive capacitor voltage balance of multilevel multileg diode-clamped converters

    OpenAIRE

    Busquets Monge, Sergio; Ruderman, Alex

    2010-01-01

    This paper presents four carrier-based PWM strategies for diode-clamped converters of any number of levels and any number of legs (phases). These carrier-based PWM strategies guarantee the dc-link capacitor voltage balance in every switching cycle without the need of additional hardware and with low dc-link capacitance values for any modulation index and load, provided that the sum of leg currents equals zero. The performance of the presented carrier-based PWM strategies,...

  20. Inter-layer slide and stress relaxation in a bilayer fluid membrane in the patch-clamp setting

    OpenAIRE

    Mukhin, Sergei I.; Baoukina, Svetlana V.

    2003-01-01

    Protein mechanosensitive channels (MS) are activated by tension transmitted through the lipid bilayer. We propose a theory of lateral stress relaxation in a bilayer lipid membrane exposed to external pressure pulse in the patch-clamp experimental setting. It is shown that transfer of lipid molecules into a strained region is thermodynamically advantageous due to local decrease of the stress. Considered stress relaxation mechanism may explain recent experimental observations (Davidson and Mart...

  1. Clamp ablation of the testes compared to bilateral orchiectomy as androgen deprivation therapy for advanced prostate cancer

    OpenAIRE

    AD Zarrabi; CF Heyns

    2011-01-01

    PURPOSE: Burdizzo clamp ablation of the testes (CAT) may provide an incisionless, cost-effective form of androgen deprivation therapy (ADT) in men with adenocarcinoma of the prostate (ACP) who find bilateral orchiectomy (BO) unacceptable or can not afford medical ADT. The aim of this study was to compare CAT with BO as primary ADT in men with ACP. MATERIALS AND METHODS: Written, informed consent was obtained from men with locally advanced or metastatic ACP. Patients were prospectively randomi...

  2. RELATIONSHIP OF TIMING OF CORD CLAMP TO THE NEONATAL HA EMATOLOGICAL STATUS OF NEWBORN - A COMPARISON IN TERM BABIES BORN VIA NORMAL VAGINAL DELIVERY & CESAREAN DELIVERY

    Directory of Open Access Journals (Sweden)

    Madhur

    2014-02-01

    Full Text Available AIM : To study the relationship of timing of cord clamping to the hematocrit and hemoglobin values within 0 - 6 hours of life - comparison in term normal vaginal delivery to cesarean delivery . Clamping and cutting of the umbilical cord at birth is by far the oldest and most prevalent intervention i n humans. In spite of that the optimal time of cord clamping has been a con troversial issue for decades . There are no formal practice guidelines as such but practitioners in western countries clamp and cut the cord immediately after birth while the pr actic e worldwide is variable . OBJECTIVE : To study and observe the effect of timing of cord clamping on neonatal hematocrit and hemoglobin within 0 – 6 hours of life & compare in term normal vaginal delivery to cesarean delivery. METHODS : This is a randomized , c ontrol trial conducted in the Dept. of Pediatrics and Dept. of Gyn & Obst. , Mahatma Gandhi Medical College & hospital. Jaipur , between 20 th to 30 th September 2013. Patients admitted in labor ward were selected according to the inclusion criteria of the study. Group A included 50 term normal vaginal delivery babies in whom the time of cord clamp from birth was noted and a cord blood or venous blood of baby was send within 6 hours of life for estimation of hematocrit & hemoglobin values , while group B incl uded 50 term babies born via cesarean section and same procedure was followed . RESULTS : It was observed that delayed cord clamping ( at 1 or 2 minutes after birth in healthy term newborns increases hematocrit & hemoglobin value within physiologic ranges wi thout causing any harmful effects . Umbilical cord clamping at 1 minute of life increases hematocrit in no more than much 8 - 10 points compared with cord clamping in first 15 seconds after birth. As per normal practice of early cord clamping in Indian scena rio timing of cord clamping in term normal vaginal delivery was at least more than 30 seconds to 1 minute while in term

  3. Solution study of the Escherichia coli DNA polymerase III clamp loader reveals the location of the dynamic ψχ heterodimer

    Directory of Open Access Journals (Sweden)

    Farzaneh Tondnevis

    2015-09-01

    Full Text Available Several X-ray crystal structures of the E. coli core clamp loader containing the five core (δ′, δ, and three truncated γ subunits have been determined, but they lack the ψ and χ subunits. We report the first solution structure of the complete seven-subunit clamp loader complex using small angle X-ray scattering. This structure not only provides information about the location of the χ and ψ subunits but also provides a model of the dynamic nature of the clamp loader complex.

  4. 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; Chen, Zhe; Liu, Jingyun

    2013-01-01

    the developed control strategy, the proposed diode-clamped circuit becomes a controllable closed loop which enables the capacitor voltages to be clamped by low power rating clamping diodes. The proposed topology and control strategy has quicker response and requires much fewer voltage sensors than the...... normally used traditional method; therefore, the system performance improvement and cost reduction are expected. Based on the proposed DCM2C, a novel N +1-level cascade multilevel topology is proposed for a cascade active power filter (CS-APF). The simulation and experimental results from the CS-APF have...

  5. Establishing a Methodology for Experimental Measuring of Loads and Stress State Determination on Clamp Dogs of Carrying Structures

    Directory of Open Access Journals (Sweden)

    E. Hristovska

    2015-12-01

    Full Text Available The experimental measuring of working loads upon the parts of rotating excavator is a complicated procedure given the complexity of the construction of the excavator and the specificity of exploitation conditions. Therefore, there are no uniform solutions and methods for this purpose, and any proposed solution is of great benefit to excavator users, as well to science studying this issue. This paper presents a preset methodology for measuring working loads of the clamp dogs on the carrying structure of the working wheel at the excavator used in surface coal mining. This methodology uses the default settings implicit to the strain gage method, which records the stresses resulting from external loads occurring within the clamp dogs’ material using strain gages and measuring equipment. Within this concept, the paper shows the manner of determining the measuring points and setting up the strain gages on both clamp dogs, the connecting with the measuring installation and the equipment. Employing diagrams, the paper presents the measurement results of static and dynamic loads, as well as induced stress state by them.

  6. A clinical comparative analysis of crush/clamp, stapler, and dissecting sealer hepatic transection methods1

    Science.gov (United States)

    Earl, T. Mark; Chari, Ravi S.; Gorden, D. Lee; Merchant, Nipun B.; Wright, J. Kelly; Feurer, Irene D.; Pinson, C. Wright

    2008-01-01

    Introduction. Several methods for hepatic parenchymal division exist. The primary aim was to assess differences in postoperative bile leaks, operative blood loss, and margin status between three transection methods: crush/clamp (CC), stapler (SP), or dissecting sealer (DS). Methods. A single institution, retrospective cohort study was performed on data collected over a three-year period in patients undergoing elective liver resection using the CC, SP, or DS. Patients were excluded if multiple methods of transection were used or for intraoperative death. The association of bile leak with transection type was assessed. A logistic regression model was tested to assess if blood loss was associated with the covariates of transection method, use of portal inflow occlusion, extent of liver resection, and other concurrent major operations. Results. Analyses included 141 patients. The stapler method was quicker than the other methods (p=0.01). The risk of postoperative bile leak was no different between CC, SP, and DS transection methods (p=0.23). There was no difference in mean blood loss or transfusions; however, hepatectomies performed with DS were associated with an increased risk of blood loss ≥1000 mL compared to CC (p=0.04). There were no differences in mean surgical margin between the three methods. Conclusion. The risk of bile leaks was not different between the three methods. While mean blood loss was similar, hepatectomy performed with the DS was associated with an increased risk of having operative blood loss ≥1000 mL compared to CC. Margins were equal by all methods. The stapler method was quicker. PMID:18982146

  7. Development of the clamp-on ultrasound flow meter for steam in pipe

    International Nuclear Information System (INIS)

    Gas flow metering of a pipe flow such as chemical plant, reactors and power stations is one of the significant techniques that enable to diagnose and control the behavior of working fluid, and to govern the entire fluid system in the industrial facilities. In order to operate the aforementioned systems, the precise measurement of the flow rate is required. The conventional flow meter, however, needs the installation of the spool piece that disturbs the stable and continuous operation of the plants. i.e., the destructive set-up process of the measurement section is necessary. In this study, the novel ultrasound gas flow metering technique has been developed by means of the clamp-on ultrasound transmitter and receivers. By the numerical simulation, the ultrasound propagation through the gas and metal pipe was firstly investigated. The effects of the external damping material, applicable vapor pressure range as well as the appropriate shape of the acoustic lens were analyzed that was followed by the feasibility test of the actual measurement system. The pressurized vapor flow was used as a working fluid. Pressure and sensor dimension were varied to compare the efficiency of the ultrasound transmission between transducers. The temperature of the working fluid was beyond 373 K. The ultrasound pulsar-receiver was used that could control the frequency, amplitude and phase of the burst sinusoids. The signal processing algorithm was developed in order to discriminate the direct signal through the gaseous flow from the unwanted circumference noise through the solid stainless pipe. The linear relation between flow rate and ultrasound peak shift was confirmed. (author)

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

    Directory of Open Access Journals (Sweden)

    Jerónimo A Auzmendi

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

  9. Hebbian induction of LTP in visual cortex: perforated patch-clamp study in cultured neurons.

    Science.gov (United States)

    Otsu, Y; Kimura, F; Tsumoto, T

    1995-12-01

    1. To see whether presynaptic activation paired with postsynaptic depolarization is necessary for the induction of long-term potentiation (LTP) in visual cortex or whether an activation of postsynaptic receptors in conjunction with depolarization is sufficient, we carried out perforated patch-clamp recordings with nystatin from cultured cortical neurons of rats. 2. Recorded neurons were monosynaptically activated either by electrical stimulation of an adjacent neuron or by direct activation of glutamate on "hot spots" of dendrites through iontophoresis or pressure ejection. In experiments in which cultured neurons were stained immunocytochemically with antibody against synaptophysin after electrophysiological recordings, hot spots were found to correspond to probable synaptic sites. 3. Excitatory postsynaptic currents (EPSCs) evoked by test stimulation applied to the adjacent neuron at 0.1 Hz were recorded at a holding potential of -60 or -70 mV for 5-10 min after an establishment of the whole cell recording configuration. Then, stimulation was paired with postsynaptic depolarization (0 mV for 200 ms) at 1 Hz for 30 or 60 s. LTP of EPSCs was induced in 7 of the 15 cells from which stable recordings were obtained for 18-30 min after pairing. 4. When postsynaptic depolarization was paired with direct glutamate application in the absence of presynaptic stimulation in 12 cells, only 1 showed LTP. Postsynaptic depolarization alone did not induce LTP in any of the six cells tested. Also, presynaptic stimulation alone did not induce LTP in any of the five cells tested. 5. These results suggest that the concurrent activation of presynaptic elements with postsynaptic depolarization is necessary for the induction of LTP in visual cortex. PMID:8747204

  10. On the Specificity of Interaction between the Saccharomyces cerevisiae Clamp Loader Replication Factor C and Primed DNA Templates during DNA Replication*

    OpenAIRE

    Hingorani, Manju M.; Coman, Maria Magdalena

    2002-01-01

    Replication factor C (RFC) catalyzes assembly of circular proliferating cell nuclear antigen clamps around primed DNA, enabling processive synthesis by DNA polymerase during DNA replication and repair. In order to perform this function efficiently, RFC must rapidly recognize primed DNA as the substrate for clamp assembly, particularly during lagging strand synthesis. Earlier reports as well as quantitative DNA binding experiments from this study indicate, however, that RFC interacts with prim...

  11. MATLAB implementation of a dynamic clamp with bandwidth of >125 kHz capable of generating I Na at 37 °C.

    Science.gov (United States)

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

    2013-04-01

    We describe the construction of a dynamic clamp with a bandwidth of >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 and 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 (I Na) 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: I Na, the hyperpolarizing-activated inward pacemaker current (I f) and an inward-rectifier K(+) current (I K1). 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

  12. Two unique ligand-binding clamps of Rhizopus oryzae starch binding domain for helical structure disruption of amylose.

    Directory of Open Access Journals (Sweden)

    Ting-Ying Jiang

    Full Text Available The N-terminal starch binding domain of Rhizopus oryzae glucoamylase (RoSBD has a high binding affinity for raw starch. RoSBD has two ligand-binding sites, each containing a ligand-binding clamp: a polyN clamp residing near binding site I is unique in that it is expressed in only three members of carbohydrate binding module family 21 (CBM21 members, and a Y32/F58 clamp located at binding site II is conserved in several CBMs. Here we characterized different roles of these sites in the binding of insoluble and soluble starches using an amylose-iodine complex assay, atomic force microscopy, isothermal titration calorimetry, site-directed mutagenesis, and structural bioinformatics. RoSBD induced the release of iodine from the amylose helical cavity and disrupted the helical structure of amylose type III, thereby significantly diminishing the thickness and length of the amylose type III fibrils. A point mutation in the critical ligand-binding residues of sites I and II, however, reduced both the binding affinity and amylose helix disruption. This is the first molecular model for structure disruption of the amylose helix by a non-hydrolytic CBM21 member. RoSBD apparently twists the helical amylose strands apart to expose more ligand surface for further SBD binding. Repeating the process triggers the relaxation and unwinding of amylose helices to generate thinner and shorter amylose fibrils, which are more susceptible to hydrolysis by glucoamylase. This model aids in understanding the natural roles of CBMs in protein-glycan interactions and contributes to potential molecular engineering of CBMs.

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

    DEFF Research Database (Denmark)

    Novak, I

    1998-01-01

    . 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......: Unstimulated duct cells had a membrane voltage (Vm) of about -50 mV. Isoproterenol had a concentration-dependent effect on Vm; at 10(-7) mol/L, it depolarized Vm by 20-25 mV and the cell conductance increased by 100 nanosiemens. These effects were a result of opening of luminal Cl- channels. Phenylephrine had...

  14. 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.; Guerrero, Josep M.

    2013-01-01

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

  15. Thermal and efficiency analysis of five-level multi-level clamped multilevel converter considering grid codes

    DEFF Research Database (Denmark)

    Ma, Ke; Muñoz-Aguilar, S.; Rodriguez, P.; Blaabjerg, Frede

    In this paper a five-level Multi-Clamped Multilevel Converter (5L-MLC2) topology is analyzed based on a typical grid integration application for renewable energy generation system. The loss and thermal distribution of the power devices in different switching legs are investigated and illustrated...... under rated operation. Afterwards, a loss and efficiency evaluation method is proposed and applied which takes into account various reactive power operation boundaries regulated by the grid codes. It is concluded that the 5L-MLC2 multilevel topology shows a good and consistent efficiency characteristic...

  16. A clamping force measurement system for monitoring the condition of bolted joints on railway track joints and points

    International Nuclear Information System (INIS)

    Many industrial structures associated with railway infrastructures rely on a large number of bolted joint connections to ensure safe and reliable operation of the track and trackside furniture. Significant sums of money are spent annually to repair the damage caused by bolt failures and to maintain the integrity of bolted structures. In the UK, Network Rail (the organization responsible for rail network maintenance and safety) conducts corrective and preventive maintenance manually on 26,000 sets of points (each having approximately 30 bolted joints per set), in order to ensure operational success and safety for the travelling public. Such manual maintenance is costly, disruptive, unreliable and prone to human error. The aim of this work is to provide a means of automatically measuring the clamping force of each individual bolted joint, by means of an instrumented washer. This paper describes the development of a sensor means to be used in the washer, which satisfies the following criteria. 1. Sense changes in the clamping force of the joint and report this fact. 2. Provide compatibility with the large dynamic range of clamping force. 3. Satisfy the limitations in terms of physical size. 4. Provide the means to electronically interface with the washer. 5. Provide a means of powering the washer in situ. 6. Provide a solution at an acceptable cost. Specifically the paper focuses on requirements 1, 2 and 3 and presents the results that support further development of the proposed design and the realization of a pre-prototype system. In the paper, various options for the force sensing element (strain gage, capacitor, piezo-resistive) have been compared, using design optimization techniques. As a result of the evaluation, piezo-resistive sensors in concert with a proprietary force attenuation method, have been found to offer the best performance and cost trade-off The performance of the novel clamping force sensor has been evaluated experimentally and the results show

  17. Regularity for a clamped grid equation $u_{xxxx}+u_{yyyy}=f $ on a domain with a corner

    OpenAIRE

    Tymofiy Gerasimov; Guido Sweers

    2009-01-01

    The operator $L=frac{partial ^{4}}{partial x^{4}} +frac{partial ^{4}}{partial y^{4}}$ appears in a model for the vertical displacement of a two-dimensional grid that consists of two perpendicular sets of elastic fibers or rods. We are interested in the behaviour of such a grid that is clamped at the boundary and more specifically near a corner of the domain. Kondratiev supplied the appropriate setting in the sense of Sobolev type spaces tailored to find the optimal regularity. Inspired...

  18. A clamping force measurement system for monitoring the condition of bolted joints on railway track joints and points

    Science.gov (United States)

    Tesfa, B.; Horler, G.; Thobiani, F. Al; Gu, F.; Ball, A. D.

    2012-05-01

    Many industrial structures associated with railway infrastructures rely on a large number of bolted joint connections to ensure safe and reliable operation of the track and trackside furniture. Significant sums of money are spent annually to repair the damage caused by bolt failures and to maintain the integrity of bolted structures. In the UK, Network Rail (the organization responsible for rail network maintenance and safety) conducts corrective and preventive maintenance manually on 26,000 sets of points (each having approximately 30 bolted joints per set), in order to ensure operational success and safety for the travelling public. Such manual maintenance is costly, disruptive, unreliable and prone to human error. The aim of this work is to provide a means of automatically measuring the clamping force of each individual bolted joint, by means of an instrumented washer. This paper describes the development of a sensor means to be used in the washer, which satisfies the following criteria. Sense changes in the clamping force of the joint and report this fact. Provide compatibility with the large dynamic range of clamping force. Satisfy the limitations in terms of physical size. Provide the means to electronically interface with the washer. Provide a means of powering the washer in situ. Provide a solution at an acceptable cost. Specifically the paper focuses on requirements 1, 2 and 3 and presents the results that support further development of the proposed design and the realization of a pre-prototype system. In the paper, various options for the force sensing element (strain gage, capacitor, piezo-resistive) have been compared, using design optimization techniques. As a result of the evaluation, piezo-resistive sensors in concert with a proprietary force attenuation method, have been found to offer the best performance and cost trade-off The performance of the novel clamping force sensor has been evaluated experimentally and the results show that a smart washer

  19. The Circuit-Level Decoupling Modulation Strategy for Three-Level Neutral-Point-Clamped (TL-NPC) Inverter

    DEFF Research Database (Denmark)

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

    2011-01-01

    In this paper, a circuit-level decoupling modulation strategy is proposed for the three-level (TL) neutral-point-clamped (NPC) inverters. With the proposed modulation scheme, the TL-NPC inverter can be decoupled into two three-level Buck converters in each defined operating section, which makes the...... controller design much simpler. The decoupling principle including the driving signal synthesis and the neutral point potential variation are analyzed detailed. It is found that switching losses can be reduced by one third and the voltage balance between the dividing dc link capacitors can be achieved...

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

    International Nuclear Information System (INIS)

    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™) 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.

  1. 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.

  2. Axisymmetric snap-through behavior of Piezo-FGM shallow clamped spherical shells under thermo-electro-mechanical loading

    International Nuclear Information System (INIS)

    Snap-through buckling of shallow clamped spherical shells made of functionally graded material (FGM) and surface-bonded piezoelectric actuators under the thermo-electro-mechanical loading is studied in this paper. The governing equations are based on the classical shell theory and the Sanders nonlinear kinematics equations. It is assumed that the property of the functionally graded materials vary continuously through the thickness of the shell according to a power law distribution of the volume fraction of the constituent materials. The constituent materials of the functionally graded shell are assumed to be mixture of ceramic and metal. The results show that the axisymmetric buckling of Piezo-FGM shallow clamped spherical shells under thermo-electro-mechanical loading is of snap-through type. The intensity of buckling is dependent on the geometry of the shell, value of thermo-electro-mechanical loading and type of thermal loading. - Highlights: • Finite diff erence method is adopted to analyze behavior of Piezo-FGM shallow spherical shell. • The eff ect of electrical loading on the behavior of Piezo-FGM shell isn't considerable. • Mechanical and thermal loading have great e ect on the axisymmetric response of shell. • Geometric dimension of shell has considerable eff ect on the response of spherical shell

  3. Obtaining Spheroplasts of Armored Dinoflagellates and First Single-Channel Recordings of Their Ion Channels Using Patch-Clamping

    Directory of Open Access Journals (Sweden)

    Ilya Pozdnyakov

    2014-09-01

    Full Text Available Ion channels are tightly involved in various aspects of cell physiology, including cell signaling, proliferation, motility, endo- and exo-cytosis. They may be involved in toxin production and release by marine dinoflagellates, as well as harmful algal bloom proliferation. So far, the patch-clamp technique, which is the most powerful method to study the activity of ion channels, has not been applied to dinoflagellate cells, due to their complex cellulose-containing cell coverings. In this paper, we describe a new approach to overcome this problem, based on the preparation of spheroplasts from armored bloom-forming dinoflagellate Prorocentrum minimum. We treated the cells of P. minimum with a cellulose synthesis inhibitor, 2,6-dichlorobenzonitrile (DCB, and found out that it could also induce ecdysis and arrest cell shape maintenance in these microalgae. Treatment with 100–250 µM DCB led to an acceptable 10% yield of P. minimum spheroplasts and was independent of the incubation time in the range of 1–5 days. We show that such spheroplasts are suitable for patch-clamping in the cell-attached mode and can form 1–10 GOhm patch contact with a glass micropipette, allowing recording of ion channel activity. The first single-channel recordings of dinoflagellate ion channels are presented.

  4. 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.

  5. 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...... for an easy implementation in a digital control platform is also presented. The good performance of the strategy is verified through both simulation and experiments in a three-level threephase neutral-point clamped converter.......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...

  6. Theoretical aspects concerning the aging behaviour of the loop of clamp spacer string in the fuel channel

    International Nuclear Information System (INIS)

    Aging of the pressure tube, a principal component of the CANDU fuel channel is a well established fact. Also known are the effects of aging upon the increase of the diameter as well as residual elongation of the pressure tube under temperature and intense radiation field influence (which after 15 years operation amount Δd ≅ 1.5 mm and Δl ≅ 75 mm, respectively). In conditions of conservation of the material volume the exterior diameter of the pressure tube increases by about 0.08 mm/year what leads effectively to an additional effort on the elastic support and, consequently, to an additional compression of the clamp string loops contacting the pressure and the calandria tubes. A theoretical computation showed that the force statically distributed upon the contact loop increases up to a value which can exceed several times the initial value after a number of years of operation. Tacking into account the fact that in running fuel channels there are accepted as admissible amplitudes of the displacement signal under the vibrations, induced by the primary coolant flow, of about 300 μm (peak-peak), the peak value of the force applied upon contact loops increases correspondingly. Consequently, the dynamical spectrum of the pressure tube vibrations will be superimposed upon the stressed clamp string contact loops. Contact loop after twisting will deform at bending. When after twisting the contact loops remain under load, the loop cross section is stressed at deformation under the action of shear axial forces and bending moment, respectively. In this work the issue was theoretically approached by means of Mohr-Maxwell method for a loop quarter. From the theoretical computation it was obtained that the contact string loop acquires in time a continuous residual deformation (some μm/year) so that one can anticipate that the contact loop will become oval-shaped. At that moment the loop will be not able to twist anymore, the stress variation will be entirely absorbed by

  7. Comprehensive Loss Evaluation of Neutral-Point-Clamped (NPC) and T-Type Three-Level Invertersbased on a Circuit Level Decoupling Modulation

    DEFF Research Database (Denmark)

    Zhang, Zhe; Anthon, Alexander; Andersen, Michael A. E.

    In this paper, an efficiency comparison ofneutral-point-clamped (NPC) inverters and bipolar switch NPC(T-Type) inverters is studied and the result shows that the T-Type inverter is more efficient at lower switching frequencies.Nevertheless, its efficiency suffers when the switching frequencyincre......In this paper, an efficiency comparison ofneutral-point-clamped (NPC) inverters and bipolar switch NPC(T-Type) inverters is studied and the result shows that the T-Type inverter is more efficient at lower switching frequencies.Nevertheless, its efficiency suffers when the switching...... orderto achieve superior output voltage quality without loweringefficiency....

  8. Connecting Rod Fatigue Life under Different Clamping Modes%不同装夹方式下的连杆疲劳寿命

    Institute of Scientific and Technical Information of China (English)

    张帷; 李辉; 梅华生; 王辉

    2014-01-01

    Objective To analyze the different results of connecting rod fatigue life detection under two different clam-ping modes, the big head clearance fit and the big head small head clearance fit. Methods The engine working conditions under different modes of the clamping were simulated using the MTS880±250 kN and MTS322±250 kN fatigue test sys-tems. And the data was processed with the SAFL data analysis method. Results The connecting rod failure probability un-der the big head clearance fit clamping mode was 5. 2×10-5 ,while the connecting rod failure probability under the big head small head clearance fit clamping mode was 0. 87×10-5 . These two kinds of clamping manners affected the fracture location of the connecting rod after fatigue test. Conclusion In the connecting rod fatigue test, the connecting rod failure probability obtained by using the big head small head clearance fit clamping was lower than that by using the big head clearance fit clamping. So we must be careful when choosing the clamping manner in the fatigue tests.%目的:分析大头间隙配合及大头小头均间隙配合这2种不同装夹方式,对连杆疲劳寿命的检测产生的不同的结果。方法采用 MTS880±500 kN 和 MTS322±250 kN 疲劳试验系统,采用不同的装夹方式模拟发动机工作状态,并通过“可靠性试验 SAFL 方法”进行数据处理。结果采用大头间隙配合装夹的连杆失效概率为5.2×10-5,大头小头均间隙配合装夹的连杆失效概率为0.87×10-5;并且2种装夹方式会影响连杆疲劳试验后的断裂位置。结论连杆疲劳试验中,采用大头小头均间隙配合装夹方式得到的连杆失效概率,较大头间隙配合装夹方式更小。进行疲劳试验需谨慎选择装夹方式。

  9. 采用LCD箝位电路的正激DC-DC变换器%A Forward DC-DC Converter with a LCD Clamp Circuit

    Institute of Scientific and Technical Information of China (English)

    王国礼; 金新民

    2000-01-01

    In this paper a forward DC-DC converter with a LCD clamp circuit is propsed. The core is reset through this simple clamp circuit, and the efficiency of the converter is improved due to avoiding the energy loss.%介绍了一种采用LCD箝位电路的正激DC-DC变换器,它以十分简单的电路结构实现了变压器铁心的磁通复位,并且避免了能量的损耗,提高了变换器的效率。

  10. Femtogram Doubly Clamped Nanomechanical Resonators Embedded in a High-Q Two-Dimensional Photonic Crystal Nanocavity

    CERN Document Server

    Sun, Xiankai; Poot, Menno; Wong, Chee Wei; Tang, Hong X

    2012-01-01

    We demonstrate a new optomechanical device system which allows highly efficient transduction of femtogram nanobeam resonators. Doubly clamped nanomechanical resonators with mass as small as 25 fg are embedded in a high-finesse two-dimensional photonic crystal nanocavity. Optical transduction of the fundamental flexural mode around 1 GHz was performed at room temperature and ambient conditions, with an observed displacement sensitivity of 0.94 fm/Hz^(1/2). Comparison of measurements from symmetric and asymmetric double-beam devices reveals hybridization of the mechanical modes where the structural symmetry is shown to be the key to obtain a high mechanical quality factor. Our novel configuration opens the way for a new category of "NEMS-in-cavity" devices based on optomechanical interaction at the nanoscale.

  11. A DC-Voltage-Balancing Circuit for a Five-Level Diode-Clamped PWM Inverter Intended for Motor Drives

    Science.gov (United States)

    Hasegawa, Kazunori; Akagi, Hirofumi

    This paper proposes a new dc-voltage-balancing circuit for a five-level diode-clamped inverter intended for a medium-voltage motor drive. This circuit consists of two unidirectional choppers and a single coupled inductor with two galvanically-isolated windings. The dc magnetic fluxes in the magnetic core, which are generated by the two windings, cancel out each other. Therefore, the inductor does not generate any dc-magnetic flux in the magnetic core. This makes the inductor compact by a factor of six compared to previously used balancing circuits containing two non-coupled inductors. Experimental results obtained from a 200-V 5.5-kW downscaled model verify that the dc mean voltages of the four split dc capacitors are balanced well under all operating conditions.

  12. 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

    In order to fulfill the continuous growing grid-side demands, the full-scale power converters are becoming more and more popular in the wind power application. Nevertheless, the more severe loading of the power semiconductor devices in the full-scale power converters, especially during Low Voltage...... Ride Through (LVRT) operation under grid faults, may compromise the reliability of the system and consequently further increase its cost. In this paper, the impact of various grid faults on a three-level Neutral-Point-Clamped (3L-NPC) grid-converter in terms of thermal loading of power semiconductor...... 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....

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

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2014-01-01

    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...

  14. Action Mechanism Research of Lanthanons to Slow Vacuolar Ion Channels in Raphanus Satirus L. (Xinlimei) Radish by Patch-Clamp

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We used whole-vacuolar patch-clamp recording mode to study the action mechanism of La3+ to Slow Vacuolar (SV) channels for the first time. We recorded SV channel currents of Xinlimei (Raphanus satirus L.) vacuolars. The minimum activation potentials of voltage-dependent SV channels lied in 25±5 mV. The increase in cytoplasmic Ca2+ led toenhancement of SV-type currents. It was found that the threshold potential of activation shifted towards more depolarized values whenever cytoplasmic Ca2+ was increased. When 10-10 mol/Lfree La3+ was added to the bath, SV-type current was suppressed by 60~75%. These data showed La3+ reduced ion permeabilities of Xinlimei root vacuolar membrane.

  15. Error Characteristics of Clamp-on Ultrasonic Flowmeters Depending on Location of Sensors and Downstream Straight Run of Bent Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Keun; Cho, Yong [Korea Water Resources Corporation, Daejeon (Korea, Republic of)

    2011-08-15

    Flowmeters that measure the amount of fluid passing through conduits must kept accurate by comparison and the periodic calibration. The reference meters used are clamp-on meters that mount sensors on the outer wall of the pipe. They are called 1-path, 2-path or 4-path flowmeters depending on the number of sensors. We selected a flowmeter mainly used for K-water as test a flowmeter. We carried out experiments to find the intrinsic error of the flowmeter and errors in the downstream of a double bent pipe. The results show that there are the sensor locations that meet the tolerance. We suggested the angle of the sensor, the straight run from the downstream of the bent pipe and the number of sensors. So it is possible to improve the water treatment process and increase the accounted water rate by upgraded flow measurement technology.

  16. Laparoscopic Non-clamping Tumor Enucleation of Renal Hilum Schwannoma in a Single Kidney: A Case Report

    Directory of Open Access Journals (Sweden)

    Fuminari Hanashima

    2015-11-01

    Full Text Available A 56-year-old woman underwent laparoscopic right nephrectomy due to pyonephrosis associated with right ureteral stones. Moreover, the patient developed a brain stem hemorrhage and became bedridden. At the time of nephrectomy, a renal tumor, with a size of 24 × 24 × 20 mm, was observed in the left renal hilum; the tumor did not show contrast enhancement on computed tomography. After 3 years, the tumor gradually grew to a size of 45 × 35 × 34 mm, and therefore, laparoscopic non-clamping tumor enucleation was performed. Pathological examination confirmed a diagnosis of renal schwannoma.

  17. Effects of BaCl2 on slow vacuolar ion channels on radish by patch-clamp

    Institute of Scientific and Technical Information of China (English)

    YANG; Pin; (杨频); ZHANG; Liping; (张丽平)

    2003-01-01

    The effects of BaCl2 on slow vacuolar (SV) currents of radish are studied by using the whole-vacuolar patch-clamp recording mode. The Ca2+-dependent SV channel can be activated by cytosolic Ca2+. When 1 mmol/L BaCl2 is added intopipette solution, SV currents are suppressed remarkably. Then adding BaCl2 of different concentrations into the bath solution, SV currents reflect different effects. The results show that BaCl2 with a lower concentration (< 3 mmol/L) promotes the channel currents and the currents are saturated when BaCl2 concentrations are between 1mmol/L and 1 mmol/L, but BaCl2 with higher concentration (≥ 3 mmol/L) inhibits SV currents.

  18. Ultraprecision XY stage using a hybrid bolt-clamped Langevin-type ultrasonic linear motor for continuous motion

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong-Jin; Lee, Sun-Kyu, E-mail: skyee@gist.ac.kr [School of Mechatronics, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 500-712 (Korea, Republic of)

    2015-01-15

    This paper presents a design and control system for an XY stage driven by an ultrasonic linear motor. In this study, a hybrid bolt-clamped Langevin-type ultrasonic linear motor was manufactured and then operated at the resonance frequency of the third longitudinal and the sixth lateral modes. These two modes were matched through the preload adjustment and precisely tuned by the frequency matching method based on the impedance matching method with consideration of the different moving weights. The XY stage was evaluated in terms of position and circular motion. To achieve both fine and stable motion, the controller consisted of a nominal characteristics trajectory following (NCTF) control for continuous motion, dead zone compensation, and a switching controller based on the different NCTFs for the macro- and micro-dynamics regimes. The experimental results showed that the developed stage enables positioning and continuous motion with nanometer-level accuracy.

  19. A novel method for the description of voltage-gated ionic currents based on action potential clamp results - Application to hippocampal mossy fiber boutons

    Directory of Open Access Journals (Sweden)

    John R Clay

    2016-01-01

    Full Text Available Action potential clamp (AP-clamp recordings of the delayed rectifier K+ current IK and the fast-activated Na+ current INa in rat hippocampal mossy fiber boutons (MFBs are analyzed using a computational technique recently reported. The method is implemented using a digitized AP from an MFB and computationally applying that that data set to published models of IK and INa. These numerical results are compared with experimental AP-clamp recordings. The INa result is consistent with experiment; the IK result is not. The difficulty with the IK model concerns the fully activated current-voltage relation, which is described here by the Goldman-Hodgkin-Katz dependence of the driving force (V-EK rather than (V-EK itself, the standard model for this aspect of ion permeation. That revision leads to the second - a much steeper voltage dependent activation curve for IK than the one obtained from normalization of a family of IK records by (V-EK. The revised model provides an improved description of the AP-clamp measurement of IK in MFBs compared with the standard approach The method described here is general. It can be used to test models of ionic currents in any excitable cell. In this way it provides a novel approach to the relationship between ionic currents and membrane excitability in neurons.

  20. 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 fact...

  1. Triglyceride glucose index as a surrogate measure of insulin sensitivity in obese adolescents with normoglycemia, prediabetes, and type 2 diabetes mellitus: Comparison with the hyperinsulinemic–euglycemic clamp

    Science.gov (United States)

    There is a need for simple surrogate estimates of insulin sensitivity in epidemiological studies of obese youth because the hyperinsulinemic-euglycemic clamp is not feasible on a large scale. Objectives: (i) To examine the triglyceride glucose (TyG) index (Ln[fasting triglycerides (mg/dL)'×'fasting ...

  2. On the problem of the stability of a rectangular plate, when the supersonic gas flow is in a direction from the free edge to the clamped edge

    OpenAIRE

    Belubekyan M.V.; Martirosyan S. R.

    2012-01-01

    The linear problem of the static stability of an elastic rectangular plate in a supersonic flow of gas is investigated. The flow is in a direction from the free edge to the clamped edge, and at the two edges parallel to the flow are hinge joint supported. Its solution shows that the divergence is possible.

  3. On the problem of the stability of a rectangular plate, when the supersonic gas flow is in a direction from the free edge to the clamped edge

    Directory of Open Access Journals (Sweden)

    Belubekyan M.V.

    2012-09-01

    Full Text Available The linear problem of the static stability of an elastic rectangular plate in a supersonic flow of gas is investigated. The flow is in a direction from the free edge to the clamped edge, and at the two edges parallel to the flow are hinge joint supported. Its solution shows that the divergence is possible.

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

    Science.gov (United States)

    Sa-ngasoongsong, Paphon; Chanplakorn, Pongsthorn; Wongsak, Siwadol; Uthadorn, Krisorn; Panpikoon, Tanapong; Jittorntam, Paisan; Aryurachai, Katcharin; Angchaisukisiri, Pantap; Kawinwonggowit, Viroj

    2015-01-01

    Background. Recently, combined intra-articular tranexamic acid (IA-TXA) injection with clamping drain method showed efficacy for blood loss and transfusion reduction in total knee replacement (TKR). However, until now, none of previous studies revealed the effect of this technique on pharmacokinetics, coagulation, and fibrinolysis. Materials and Methods. An experimental study was conducted, during 2011-2012, in 30 patients undergoing unilateral TKR. Patients received IA-TXA application and then were allocated into six groups regarding clamping drain duration (2-, 4-, 6-, 8-, 10-, and 12-hours). Blood and drainage fluid were collected to measure tranexamic acid (TXA) level and related coagulation and fibrinolytic markers. Postoperative complication was followed for one year. Results. There was no significant difference of serum TXA level at 2 hour and 24 hour among groups (p < 0.05). Serum TXA level at time of clamp release was significantly different among groups with the highest level at 2 hour (p < 0.0001). There was no significant difference of TXA level in drainage fluid, postoperative blood loss, blood transfusion, and postoperative complications (p < 0.05).  Conclusions. Low-dose IA-TXA application in TKR with prolonged clamping drain method is a safe and effective blood conservative technique with only minimal systemic absorption and without significant increase in systemic absorption over time. PMID:26583092

  5. 数控车床液压卡盘夹紧控制系统的研究%Research of CNC lathe chuck clamping hydraulic control system

    Institute of Scientific and Technical Information of China (English)

    张文亭

    2014-01-01

    主要研究数控车床液压卡盘夹紧控制系统,建立了动力卡盘的夹紧力和转速之间的关系模型,分析了基于供油压力随速度变化的夹紧力补偿,设计了动力卡盘的夹紧控制系统的油路,通过试验验证了采用液压压力补偿的卡盘控制系统具有较好的高速性能。%This paper studies the CNC lathe chuck clamping hydraulic control system, established the model of the relationship between a power chuck clamping force and speed, analysis of the speed change based on the oil pressure with a clamping force compensation, designed chuck clamping force control system hydraulic circuit, verified by experiment using a pressure compensated hydraulic chuck control system has good high speed performance.

  6. Mechanistic Insight into CM18-Tat11 Peptide Membrane-Perturbing Action by Whole-Cell Patch-Clamp Recording

    Directory of Open Access Journals (Sweden)

    Anna Fasoli

    2014-07-01

    Full Text Available The membrane-destabilization properties of the recently-introduced endosomolytic CM18-Tat11 hybrid peptide (KWKLFKKIGAVLKVLTTG-YGRKKRRQRRR, residues 1–7 of cecropin-A, 2–12 of melittin, and 47–57 of HIV-1 Tat protein are investigated in CHO-K1 cells by using the whole-cell configuration of the patch-clamp technique. CM18-Tat11, CM18, and Tat11 peptides are administered to the cell membrane with a computer-controlled micro-perfusion system. CM18-Tat11 induces irreversible cell-membrane permeabilization at concentrations (≥4 µM at which CM18 triggers transient pore formation, and Tat11 does not affect membrane integrity. We argue that the addition of the Tat11 module to CM18 is able to trigger a shift in the mechanism of membrane destabilization from “toroidal” to “carpet”, promoting a detergent-like membrane disruption. Collectively, these results rationalize previous observations on CM18-Tat11 delivery properties that we believe can guide the engineering of new modular peptides tailored to specific cargo-delivery applications.

  7. MEMS-based force-clamp analysis of the role of body stiffness in C. elegans touch sensation.

    Science.gov (United States)

    Petzold, Bryan C; Park, Sung-Jin; Mazzochette, Eileen A; Goodman, Miriam B; Pruitt, Beth L

    2013-06-01

    Touch is enabled by mechanoreceptor neurons in the skin and plays an essential role in our everyday lives, but is among the least understood of our five basic senses. Force applied to the skin deforms these neurons and activates ion channels within them. Despite the importance of the mechanics of the skin in determining mechanoreceptor neuron deformation and ultimately touch sensation, the role of mechanics in touch sensitivity is poorly understood. Here, we use the model organism Caenorhabditis elegans to directly test the hypothesis that body mechanics modulate touch sensitivity. We demonstrate a microelectromechanical system (MEMS)-based force clamp that can apply calibrated forces to freely crawling C. elegans worms and measure touch-evoked avoidance responses. This approach reveals that wild-type animals sense forces force sensitivity, while having only modest effects on indentation sensitivity. We investigate the theoretical body deformation predicted under applied force and conclude that local mechanical loads induce inward bending deformation of the skin to drive touch sensation in C. elegans. PMID:23598612

  8. Glucose uptake and pulsatile insulin infusion: euglycaemic clamp and [3-3H]glucose studies in healthy subjects

    International Nuclear Information System (INIS)

    To test the hypothesis that insulin has a greater effect on glucose metabolism when given as pulsatile than as continuous infusion, a 354-min euglycaemic clamp study was carried out in 8 healthy subjects. At random order soluble insulin was given intravenously either at a constant rate of 0.45mU/kg · min or in identical amounts in pulses of 11/2 to 21/4 min followed by intervals of 101/2 to 93/4 min. Average serum insulin levels were similar during the two infusion protocols, but pulsatile administration induced oscillations ranging between 15 and 62 μU/ml. Glucose uptake expressed as metabolic clearance rate (MCR) for glucose was significantly increased during pulsatile insulin delivery as compared with continuous administration (270-294 min: 8.7±0.7 vs 6.8±0.9 ml/kg · min, P 3H]glucose infusion technique was suppressed to insignificant values. Finally, the effect of insulin on endogenous insulin secretion and lipolysis as assessed by changes in serum C-peptide and serum FFA was uninfluenced by the infusion mode. In conclusion, insulin infusion resulting in physiological serum insulin levels enhances glucose uptake in peripheral tissues in healthy subjects to a higher degree when given in a pulsed pattern mimicking that of the normal endocrine pancreas than when given as a continuous infusion. (author)

  9. Mechanistic insight into CM18-Tat11 peptide membrane-perturbing action by whole-cell patch-clamp recording.

    Science.gov (United States)

    Fasoli, Anna; Salomone, Fabrizio; Benedusi, Mascia; Boccardi, Claudia; Rispoli, Giorgio; Beltram, Fabio; Cardarelli, Francesco

    2014-01-01

    The membrane-destabilization properties of the recently-introduced endosomolytic CM18-Tat11 hybrid peptide (KWKLFKKIGAVLKVLTTG-YGRKKRRQRRR, residues 1-7 of cecropin-A, 2-12 of melittin, and 47-57 of HIV-1 Tat protein) are investigated in CHO-K1 cells by using the whole-cell configuration of the patch-clamp technique. CM18-Tat11, CM18, and Tat11 peptides are administered to the cell membrane with a computer-controlled micro-perfusion system. CM18-Tat11 induces irreversible cell-membrane permeabilization at concentrations (≥4 µM) at which CM18 triggers transient pore formation, and Tat11 does not affect membrane integrity. We argue that the addition of the Tat11 module to CM18 is able to trigger a shift in the mechanism of membrane destabilization from "toroidal" to "carpet", promoting a detergent-like membrane disruption. Collectively, these results rationalize previous observations on CM18-Tat11 delivery properties that we believe can guide the engineering of new modular peptides tailored to specific cargo-delivery applications. PMID:24991756

  10. 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.

  11. Regularity for a clamped grid equation $u_{xxxx}+u_{yyyy}=f $ on a domain with a corner

    Directory of Open Access Journals (Sweden)

    Tymofiy Gerasimov

    2009-04-01

    Full Text Available The operator $L=frac{partial ^{4}}{partial x^{4}} +frac{partial ^{4}}{partial y^{4}}$ appears in a model for the vertical displacement of a two-dimensional grid that consists of two perpendicular sets of elastic fibers or rods. We are interested in the behaviour of such a grid that is clamped at the boundary and more specifically near a corner of the domain. Kondratiev supplied the appropriate setting in the sense of Sobolev type spaces tailored to find the optimal regularity. Inspired by the Laplacian and the Bilaplacian models one expect, except maybe for some special angles that the optimal regularity improves when angle decreases. For the homogeneous Dirichlet problem with this special non-isotropic fourth order operator such a result does not hold true. We will show the existence of an interval $( frac{1}{2}pi ,omega _{star }$, $omega _{star }/pi approx 0.528dots$ (in degrees $omega _{star }approx 95.1dots^{circ} $, in which the optimal regularity improves with increasing opening angle.

  12. The influence of rotary inertia of concentrated masses on the natural vibrations of a clamped-supported pipe conveying fluid

    International Nuclear Information System (INIS)

    Effects of rotary inertia of concentrated masses on the natural vibrations of a fluid-conveying pipe have been studied by theoretical modeling and numerical calculations. For the analysis, a clamped-supported pipe is assumed and Galerkin's method is used for transformation of the governing equation to the eigenvalue problem. The natural frequencies and mode shapes for the system have been calculated by using the newly developed computer code. In addition, the threshold values of flow velocity for the onset of unstable motions have been investigated. The main conclusions for the present study are (1) rotary inertia gives much change on the higher natural frequencies and mode shapes, (2) the number and location of nodes can be changed by rotary inertia, (3) by introducing rotary inertia, the second natural frequency approaches the first as the location of the concentrated mass approaches the midspan of the pipe, and (4) the critical fluid velocities are unchanged by introduction of rotary inertia and the first three dimensionless values are u∼4.49, 7.73, and 10.91, respectively. (orig.)

  13. Structure of p15PAF-PCNA complex and implications for clamp sliding during DNA replication and repair

    Science.gov (United States)

    de Biasio, Alfredo; de Opakua, Alain Ibáñez; Mortuza, Gulnahar B.; Molina, Rafael; Cordeiro, Tiago N.; Castillo, Francisco; Villate, Maider; Merino, Nekane; Delgado, Sandra; Gil-Cartón, David; Luque, Irene; Diercks, Tammo; Bernadó, Pau; Montoya, Guillermo; Blanco, Francisco J.

    2015-03-01

    The intrinsically disordered protein p15PAF regulates DNA replication and repair by binding to the proliferating cell nuclear antigen (PCNA) sliding clamp. We present the structure of the human p15PAF-PCNA complex. Crystallography and NMR show the central PCNA-interacting protein motif (PIP-box) of p15PAF tightly bound to the front-face of PCNA. In contrast to other PCNA-interacting proteins, p15PAF also contacts the inside of, and passes through, the PCNA ring. The disordered p15PAF termini emerge at opposite faces of the ring, but remain protected from 20S proteasomal degradation. Both free and PCNA-bound p15PAF binds DNA mainly through its histone-like N-terminal tail, while PCNA does not, and a model of the ternary complex with DNA inside the PCNA ring is consistent with electron micrographs. We propose that p15PAF acts as a flexible drag that regulates PCNA sliding along the DNA and facilitates the switch from replicative to translesion synthesis polymerase binding.

  14. Investigation on natural diets of larval marine animals using peptide nucleic acid-directed polymerase chain reaction clamping.

    Science.gov (United States)

    Chow, Seinen; Suzuki, Sayaka; Matsunaga, Tadashi; Lavery, Shane; Jeffs, Andrew; Takeyama, Haruko

    2011-04-01

    The stomach contents of the larvae of marine animals are usually very small in quantity and amorphous, especially in invertebrates, making morphological methods of identification very difficult. Nucleotide sequence analysis using polymerase chain reaction (PCR) is a likely approach, but the large quantity of larval (host) DNA present may mask subtle signals from the prey genome. We have adopted peptide nucleic acid (PNA)-directed PCR clamping to selectively inhibit amplification of host DNA for this purpose. The Japanese spiny lobster (Panulirus japonicus) and eel (Anguilla japonica) were used as model host and prey organisms, respectively. A lobster-specific PNA oligomer (20 bases) was designed to anneal to the sequence at the junction of the 18 S rDNA gene and the internal transcribed spacer 1 (ITS1) of the lobster. PCR using eukaryote universal primers for amplifying the ITS1 region used in conjunction with the lobster-specific PNA on a mixed DNA template of lobster and eel demonstrated successful inhibition of lobster ITS1 amplification while allowing efficient amplification of eel ITS1. This method was then applied to wild-caught lobster larvae of P. japonicus and P. longipes bispinosus collected around Ryukyu Archipelago, Japan. ITS1 sequences of a wide variety of animals (Ctenophora, Cnidaria, Crustacea, Teleostei, Mollusca, and Chaetognatha) were detected. PMID:20535520

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

    International Nuclear Information System (INIS)

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

  16. Optimal Design of the Five-Hinge Diagonal Row Hyperbolic Elbow Clamping Mechanism of Injection Molding Machines’ Clamping Systems Based on MATLAB%基于MATLAB的注塑机五支铰斜排双曲肘合模系统优化设计

    Institute of Scientific and Technical Information of China (English)

    石绍伟; 杜思莹; 杜遥雪; 徐百平

    2014-01-01

    对80T注塑机五支铰斜排双曲肘合模机构的运动特性和力学特性进行分析,确立以行程比和合模油缸推力放大倍数为优化目标,建立合模机构优化数学模型,确定参数化设计流程,并根据几何关系设立合理的约束参数,用 MATLAB 软件对合模机构进行优化设计.优化后,该机构行程比提高了31.91%,合模油缸推力放大倍数提高了0.46%,为降低五点斜排双曲肘合模机构的能耗,提高工作效率及注塑件的质量提供理论依据.%This study analyses the movement characteristics and mechanical properties of the five-hinge diagonal row hyperbolic elbow clamping mechanism of the 80T injection molding machine, establishes the stroke-bore ratio and enlargement of the thrust of the clamping cylinder as the optimization goal, builds the optimization mathematical model of the clamping mechanism, determines the parametric design process, chooses reasonable constraint parameters according to geometry relationship, and uses the MATLAB software to optimize design for the clamping mechanism. After optimization, the stroke-bore ratio improves by 31.91% and the enlargement of the thrust of clamping cylinder by 0.46%. The improved design provides a theoretical basis for reducing the energy consumption of the five-point diagonal row hyperbolic elbow clamping mechanism and improving its working efficiency and the quality of injection molded parts.

  17. 一种新型液压夹持机构的设计与计算%Design and Calculation of a New Type of Hydraulic Clamping Mechanism

    Institute of Scientific and Technical Information of China (English)

    李小平; 刘海兰

    2014-01-01

    Through analyzing the forces of the transmission component in a new type of hydraulic clamping mechanism,a formula was exported which could be used to calculate the thrust on the piston rod when the mechanism worked. On this basis,the cylinders’ model was selected and the strength of the piston rod was checked. These provide theoretical bases for design of this hydraulic clamping mechanism.%通过对一种新型液压夹持机构中各传力构件进行受力分析,导出了该机构工作时活塞杆的推力计算公式。以此为基础,进行了液压缸的选型和活塞杆的强度校核,为该种新型液压夹持机构的设计提供了理论依据。

  18. High-frequency link dc/ac converter with suppressed voltage clamp circuits -- Naturally commutated phase angle control with self turn-off devices

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, Mikihiko; Nagai, Masaki; Mochizuki, Masayuki; Nabae, Akira [Tokyo Inst. of Polytechnics, Kanagawa (Japan). Dept. of Electronic Engineering

    1996-03-01

    High-frequency (HF) link circuit topology is advantageous in realizing compact and light-weight power converters for UPS systems, new energy systems, etc. Among its several circuit configurations, so called cycloconverter type dc/ac converter has its inherent merit of bidirectional power flow and fewer power conversion stages. But, without additional voltage clamp circuit, voltage surge occurs at the moment of PWM switchings of the cycloconverter due to the stored energy in the leakage inductance at the HF transformer. In this paper, a new approach which adopts only natural-commutation phase angle control for the cycloconverter stage instead of PWM is proposed to remove such voltage clamp circuits. Experimental results of the prototype system which include the application as an ac active filter are also shown.

  19. Effects of glucagon-like peptide 1 on counterregulatory hormone responses, cognitive functions, and insulin secretion during hyperinsulinemic, stepped hypoglycemic clamp experiments in healthy volunteers

    DEFF Research Database (Denmark)

    Nauck, Michael A; Heimesaat, Markus M; Behle, Kai; Holst, Jens Juul; Nauck, Markus S; Ritzel, Robert; Hüfner, Michael; Schmiegel, Wolff H

    2002-01-01

    neuroglucopenic symptoms were assessed, and cognitive function was tested at each plateau. Insulin secretion rates were estimated by deconvolution (two-compartment model of C-peptide kinetics). At insulin concentrations of approximately 45 mU/liter, glucose infusion rates were similar with and without GLP-1 (P...... other counterregulatory hormones and autonomic or neuroglucopenic symptom scores increased, and cognitive functions decreased with decreasing glucose concentrations, but there were no significant differences comparing experiments with GLP-1 or placebo, except for a significant reduction of GH responses...... with normal oral glucose tolerance received infusions of regular insulin (1 mU x kg(-1) x min(-1)) over 360 min on two occasions in the fasting state. Capillary glucose concentrations were clamped at plateaus of 4.3, 3.7, 3.0, and 2.3 mmol/liter for 90 min each (stepwise hypoglycemic clamp); on one...

  20. Results from the carbon-land model intercomparison project (C-LAMP) and availability of the data on the earth system grid (ESG)

    International Nuclear Information System (INIS)

    This paper describes the Carbon-Land Model Intercomparison Project (C-LAMP) being carried out through a collaboration between the Community Climate System Model (CCSM) Biogeochemistry Working Group, a DOE SciDAC-2 project, and the DOE Program for Climate Model Diagnosis and Intercomparison (PCMDI). The goal of the project is to intercompare terrestrial biogeochemistry models running within the CCSM framework to determine the best set of processes to include in future versions of CCSM. As a part of the project, observational datasets are being collected and used to score the scientific performance of these models following a well-defined set of metrics. In addition, metadata standards for terrestrial biosphere models are being developed to support archival and distribution of the C-LAMP model output via the Earth System Grid (ESG). Progress toward completion of this project and preliminary results from the first set of experiments are reported

  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

    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. Do we need to clamp the renal hilum liberally during the initial phase of the learning curve of robot-assisted nephron-sparing surgery?

    OpenAIRE

    Acar, Ömer; Esen, Tarık; Musaoğlu, Ahmet; Vural, Metin

    2014-01-01

    Objective. We aimed to compare the results of our initial robot-assisted nephron-sparing surgeries (RANSS) performed with or without hilar clamping. Material and Method. Charts of the initial RANSSs (n=44), which were performed by a single surgeon, were retrospectively reviewed. R.E.N.A.L. nephrometry system, modified Clavien classification, and M.D.R.D. equation were used to record tumoral complexity, complications, and estimated glomerular filtration rate (eGFR), respectively. Outcomes of t...

  3. Patch-clamp analysis of voltage-activated and chemically activated currents in the vomeronasal organ of Sternotherus odoratus (stinkpot/musk turtle)

    OpenAIRE

    Fadool, D. A.; Wachowiak, M.; Brann, J. H.

    2001-01-01

    The electrophysiological basis of chemical communication in the specialized olfactory division of the vomeronasal (VN) organ is poorly understood. In total, 198 patch-clamp recordings were made from 42 animals (Sternotherus odoratus, the stinkpot/musk turtle) to study the electrically and chemically activated properties of VN neurons. The introduction of tetramethylrhodamine-conjugated dextran into the VN orifice permitted good visualization of the vomeronasal neural epithelium prior to disso...

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

    OpenAIRE

    Paphon Sa-ngasoongsong; Pongsthorn Chanplakorn; Siwadol Wongsak; Krisorn Uthadorn; Tanapong Panpikoon; Paisan Jittorntam; Katcharin Aryurachai; Pantap Angchaisukisiri; Viroj Kawinwonggowit

    2015-01-01

    Background. Recently, combined intra-articular tranexamic acid (IA-TXA) injection with clamping drain method showed efficacy for blood loss and transfusion reduction in total knee replacement (TKR). However, until now, none of previous studies revealed the effect of this technique on pharmacokinetics, coagulation, and fibrinolysis. Materials and Methods. An experimental study was conducted, during 2011-2012, in 30 patients undergoing unilateral TKR. Patients received IA-TXA application and th...

  5. The Development and Modelling of a Novel Clamp-on Ultrasonic-Thermal and Ultrasonic Multiple Reflection Flowmeter for Liquid Applications.

    OpenAIRE

    Law, Masa

    1994-01-01

    The development of a novel combined "ultrasonic/thermal" with "ultrasonic multiple reflections" clamp-on meter for measuring a wide flowrate range of clean liquids in small diameter pipes is presented. Current existing flowmeters based on ultrasound cannot measure very low flowrates for single phase liquids. The ultrasonic/thermal technique can measure single phase flows in the range 0 to 0.6 m s' in pipes with diameters as small as 15 mm. It can also detect and measure reverse...

  6. Using a Harmonic Scalpel "Drilling and Clamping" Method to Implement Zero Ischemic Robotic-assisted Partial Nephrectomy: An Observation Case Report Study.

    Science.gov (United States)

    Hou, Chen-Pang; Lin, Yu-Hsiang; Hsu, Yu-Chao; Chen, Chien-Lun; Chang, Phei-Lang; Tsui, Ke-Hung

    2016-01-01

    Robot-assisted partial nephrectomy (RAPN) has gradually become a popular minimally invasive nephron-sparing surgical option for small renal tumors. Ischemic injury should be minimized because it impacts renal function outcomes following partial nephrectomy. Herein, the authors detail the technique and present initial perioperative outcomes of our novel harmonic scalpel "drilling and clamping" method to implement zero-ischemic RAPN. The authors prospectively collected baseline and perioperative data of patients who underwent zero ischemic RAPN performed by our harmonic scalpel "drilling and clamping" method. From April 2012 to December 2014, a total of 19 consecutive zero ischemic RAPN procedures were performed by a single surgeon. For 18 of the 19 patients, RAPN using our harmonic scalpel "Drilling and Clamping" method was successfully completed without the need for hilar clamping. The median tumor size was 3.4 cm (range: 1.8-6.2); operative time was 3.2 hours (range: 1.9-4.5); blood loss was 100 mL (range: 30-950); and postoperative hospital stay was 4 days (3-26). One patient required intraoperative blood transfusion. Two patients had intra or postoperative complications: 1 was converted to traditional laparotomy because of massive bleeding, whereas another had postoperative stress ulcer. Pathology confirmed renal cell carcinoma in 13 patients (63.2%), angiomyolipoma in 6 patients: (31.5%), and oncocytoma in 1 patient (5.3%). Mean pre- and postoperative serum creatinine (0.82 mg/dL and 0.85 mg/dL, respectively), estimated glomerular filtration rate (84.12 and 82.18, respectively), and hemoglobin (13.27 g/dL and 12.71 g/dL, respectively) were comparable. The authors present a novel zero-ischemic technique for RAPN. They believe that this technique is feasible and reproducible. PMID:26817867

  7. Do We Need to Clamp the Renal Hilum Liberally during the Initial Phase of the Learning Curve of Robot-Assisted Nephron-Sparing Surgery?

    Directory of Open Access Journals (Sweden)

    Ömer Acar

    2014-01-01

    Full Text Available Objective. We aimed to compare the results of our initial robot-assisted nephron-sparing surgeries (RANSS performed with or without hilar clamping. Material and Method. Charts of the initial RANSSs (n=44, which were performed by a single surgeon, were retrospectively reviewed. R.E.N.A.L. nephrometry system, modified Clavien classification, and M.D.R.D. equation were used to record tumoral complexity, complications, and estimated glomerular filtration rate (eGFR, respectively. Outcomes of the clamped (group 1, n=14 versus off-clamp (group 2, n=30 RANSSs were compared. Results. The difference between the two groups was insignificant regarding mean patient age, mean tumor size, and mean R.E.N.A.L. nephrometry score. Mean operative time, mean estimated blood loss amount, and mean length of hospitalization were similar between groups. A total of 4 patients in each group suffered 11 Clavien grade ≥2 complications early postoperatively. Open conversion rates were similar. The difference between the 2 groups in terms of the mean postoperative change in eGFR was insignificant. We did not encounter any local recurrence after a mean follow-up of 18.9 months. Conclusions. Creating warm-ischemic conditions during RANSS should not be a liberal decision, even in the initial phases of the learning curve for a highly experienced open surgeon.

  8. Substrate clamping effect onto magnetoelectric coupling in multiferroic BaTiO3-CoFe2O4 core-shell nanofibers via coaxial electrospinning

    Science.gov (United States)

    Fu, Bi; Lu, Ruie; Gao, Kun; Yang, Yaodong; Wang, Yaping

    2015-10-01

    We report large lateral magnetoelectric (ME) coupling coefficients α 31 of 1.2×104 \\text{mV} \\text{cm}-1 \\text{Oe}-1 and 3.5× 104 \\text{mV} \\text{cm}-1 \\text{Oe}-1 in substrate bonded and free-standing multiferroic BaTiO3-CoFe2O4 (BTO-CFO) core-shell nanofibers (NFs) with and without substrate clamping effect, respectively. The BTO-CFO core-shell NFs were synthesised by a sol-gel coaxial electrospinning technique, and their ME coupling was directly observed by demonstrating the evolution of piezoelectric coefficient (d 33), ferroelectric domain, and phase contrast induced by an external magnetic field. These impressed α 31 coefficients originated from the nanoconfinement of the interphase elastic interaction between the ferromagnetic core fiber and the ferroelectric shell interlayer, as well as the strain transformation at the one-dimensional (1D) fiber boundary. This means that the decreasing substrate clamping effect results in an enhanced ME coupling in multiferroic NFs, which is similar to that of thin films. These findings make people understand the substrate clamping effect and enable nanoscale ME device applications.

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

    Directory of Open Access Journals (Sweden)

    Hui Wu

    2014-01-01

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

  10. Functional and morphological assessment of a standardized rat sciatic nerve crush injury with a non-serrated clamp.

    Science.gov (United States)

    Varejão, Artur S P; Cabrita, António M; Meek, Marcel F; Bulas-Cruz, José; Melo-Pinto, Pedro; Raimondo, Stefania; Geuna, Stefano; Giacobini-Robecchi, Maria G

    2004-11-01

    Peripheral nerve researchers frequently use the rat sciatic nerve crush as a model for axonotmesis. Unfortunately, studies from various research groups report results from different crush techniques and by using a variety of evaluation tools, making comparisons between studies difficult. The purpose of this investigation was to determine the sequence of functional and morphologic changes after an acute sciatic nerve crush injury with a non-serrated clamp, giving a final standardized pressure of p = 9 MPa. Functional recovery was evaluated using the sciatic functional index (SFI), the extensor postural thrust (EPT) and the withdrawal reflex latency (WRL), before injury, and then at weekly intervals until week 8 postoperatively. The rats were also evaluated preoperatively and at weeks 2, 4, and 8 by ankle kinematics, toe out angle (TOA), and gait-stance duration. In addition, the motor nerve conduction velocity (MNCV) and the gastrocnemius-soleus weight parameters were measured just before euthanasia. Finally, structural, ultrastructural and histomorphometric analyses were carried out on regenerated nerve fibers. At 8 weeks after the crush injury, a full functional recovery was predicted by SFI, EPT, TOA, and gait-stance duration, while all the other parameters were still recovering their original values. On the other hand, only two of the histomorphometric parameters of regenerated nerve fibers, namely myelin thickness/axon diameter ratio and fiber/axon diameter ratio, returned to normal values while all other parameters were significantly different from normal values. The employment of traditional methods of functional evaluation in conjunction with the modern techniques of computerized analysis of gait and histomorphometric analysis should thus be recommended for an overall assessment of recovery in the rat sciatic nerve crush model. PMID:15684656

  11. Glucose uptake and pulsatile insulin infusion: euglycaemic clamp and (3-/sup 3/H)glucose studies in healthy subjects

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, O.; Arnfred, J.; Hother Nielsen, O.; Beck-Nielsen, H.; Oerskov, H.

    1986-01-01

    To test the hypothesis that insulin has a greater effect on glucose metabolism when given as pulsatile rather than as continuous infusion, a 354-min euglycaemic clamp study was carried out in 8 healthy subjects. At random order soluble insulin was given intravenously either at a constant rate of 0.45mU/kg center dot min or in identical amounts in pulses of 1/sup 1///sub 2/ to 2/sup 1///sub 4/ min followed by intervals of 10/sup 1///sub 2/ to 9/sup 3///sub 4/ min. Average serum insulin levels were similar during the two infusion protocols, but pulsatile administration induced oscillations ranging between 15 and 62 ..mu..U/ml. Glucose uptake expressed as metabolic clearance rate (MCR) for glucose was significantly increased during pulsatile insulin delivery as compared with continuous administration (270-294 min: 8.7+-0.7 vs 6.8+-0.9 ml/kg center dot min, P < 0.01, and 330-354 min: 8.9 +- 0.5 vs 7.4 +- 0.9 ml/kg center dotmin, P<0.05). The superior efficacy of pulsatile insulin delivery on glucose uptake was not consistently found until after 210 min of insulin administration. In both infusion protocols, endogenous glucose production as estimated by the (3-/sup 3/H)glucose infusion technique was suppressed to insignificant values. Finally, the effect of insulin on endogenous insulin secretion and lipolysis as assessed by changes in serum C-peptide and serum FFA was uninfluenced by the infusion mode. In conclusion, insulin infusion resulting in physiological serum insulin levels enhances glucose uptake in peripheral tissues in healthy subjects to a higher degree when given in a pulsed pattern mimicking that of the normal endocrine pancreas than when given as a continuous infusion.

  12. Application of an alcohol clamp paradigm to examine inhibitory control, subjective responses, and acute tolerance in late adolescence.

    Science.gov (United States)

    Hendershot, Christian S; Wardell, Jeffrey D; Strang, Nicole M; Markovich, Mike S D; Claus, Eric D; Ramchandani, Vijay A

    2015-06-01

    Individual differences in acute alcohol effects on cognitive control and subjective responses--and acute tolerance to these effects--are implicated in the risk for heavy drinking and alcohol-related harms. Few studies have examined these effects in drinkers under age 21. Additionally, studies of acute tolerance typically involve bolus oral alcohol administration, such that estimates of tolerance are confounded with blood alcohol concentration (BAC) limb. The current study examined cognitive control and subjective responses in young heavy drinkers (n = 88; M = 19.8 years old, SD = 0.8) during a single-session alcohol clamp protocol. Participants completed an intravenous alcohol session comprising an ascending limb (0 to 80 mg% in 20 min) and a BAC plateau (80 mg% for 80 min). Serial assessments included a cued go/no-go task and measures of stimulation, sedation, and craving. Relevant individual difference factors (attention-deficit hyperactivity disorder [ADHD] symptoms and sensation seeking) were examined as moderators. Multilevel modeling demonstrated that response inhibition worsened following initial rise in BAC and showed increasing impairment during the BAC plateau. ADHD symptoms and sensation seeking moderated this effect. Significant within-person associations between stimulation and craving were evident on the ascending limb only. Participants with higher ADHD symptoms reported steeper increases in stimulation during the ascending limb. These findings provide initial information about subjective and behavioral responses during pseudoconstant BAC, and potential moderators of these outcomes, in late adolescence. Additional studies with placebo-controlled designs are necessary to confirm these findings. PMID:26053322

  13. Clamp ablation of the testes compared to bilateral orchiectomy as androgen deprivation therapy for advanced prostate cancer

    Directory of Open Access Journals (Sweden)

    AD Zarrabi

    2011-06-01

    Full Text Available PURPOSE: Burdizzo clamp ablation of the testes (CAT may provide an incisionless, cost-effective form of androgen deprivation therapy (ADT in men with adenocarcinoma of the prostate (ACP who find bilateral orchiectomy (BO unacceptable or can not afford medical ADT. The aim of this study was to compare CAT with BO as primary ADT in men with ACP. MATERIALS AND METHODS: Written, informed consent was obtained from men with locally advanced or metastatic ACP. Patients were prospectively randomized to BO (n = 9 or CAT (n = 10 under local anaesthesia, and were evaluated 3 and 7 days, 6 weeks and 3 months post-procedure. The protocol was approved by the local institutional ethics committee. Statistical analysis was performed using Student's, Mann-Whitney's and Fisher's tests. RESULTS: Mean duration of the procedure was significantly longer for BO than CAT (16.9 vs. 10.9 minutes. Mean pain scores during and after the procedure did not differ significantly. Serum testosterone decreased significantly on days 3 and 7 after CAT, but increased at 6 weeks, and was significantly higher than after BO. Serum luteinizing hormone increased significantly from day 3 after BO and from day 7 after CAT. Serum prostate specific antigen decreased significantly after BO, but not after CAT. Minor complications were more common after BO (89% than CAT (40%. In the 9 men who did not achieve castrate levels of testosterone after CAT, BO was performed. CONCLUSIONS: CAT was quicker to perform and had a lower complication rate, but was not as effective as BO in achieving castrate serum testosterone levels.

  14. Molecular Dissection of the Homotrimeric Sliding Clamp of T4 Phage: Two Domains of a Subunit Display Asymmetric Characteristics.

    Science.gov (United States)

    Singh, Manika Indrajit; Jain, Vikas

    2016-01-26

    Sliding clamp proteins are circular dimers or trimers that encircle DNA and serve as processivity factors during DNA replication. Their presence in all the three domains of life and in bacteriophages clearly indicates their high level of significance. T4 gp45, besides functioning as the DNA polymerase processivity factor, also moonlights as the late promoter transcription determinant. Here we report a detailed biophysical analysis of gp45. The chemical denaturation of gp45 probed by circular dichroism spectroscopy, tryptophan fluorescence anisotropy, and blue-native polyacrylamide gel electrophoresis suggests that the protein follows a three-state denaturation profile and displays an intermediate molten globule-like state. The three-state transition was found to be the result of the sequential unfolding of the two domains, the N-terminal domain (NTD) and the C-terminal domain (CTD), of gp45. The experiments involving Trp fluorescence quenching by acrylamide demonstrate that the CTD undergoes substantial changes in conformation during formation of the intermediate state. Further biophysical dissection of the individual domain reveals contrasting properties of the two domains. The NTD unfolds at low urea concentrations and is also susceptible to protease cleavage, whereas the CTD resists urea-mediated denaturation and is not amenable to protease digestion even at higher urea concentrations. These experiments allow us to conclude that the two domains of gp45 differ in their dynamics. While the CTD shows stability and rigidity, we find that the NTD is unstable and flexible. We believe that the asymmetric characteristics of the two domains and the interface they form hold significance in gp45 structure and function. PMID:26735934

  15. Suitport Feasibility - Human Pressurized Space Suit Donning Tests with the Marman Clamp and Pneumatic Flipper Suitport Concepts

    Science.gov (United States)

    Boyle, Robert M.; Rodriggs, Liana; Allton, Charles; Jennings, Mallory; Aitchision, Lindsay

    2013-01-01

    The suitport concept has been recently implemented as part of the small pressurized lunar rover (Currently the Space Exploration vehicle, or SEV) and the Multi-Mission Space Exploration Vehicle (MMSEV) concept demonstrator vehicle. Suitport replaces or augments the traditional airlock function of a spacecraft by providing a bulkhead opening, capture mechanism, and sealing system to allow ingress and egress of a space suit while the space suit remains outside of the pressurized volume of the spacecraft. This presents significant new opportunities to EVA exploration in both microgravity and surface environments. The suitport concept will enable three main improvements in EVA by providing reductions in: pre-EVA time from hours to less than thirty minutes; airlock consumables; contamination returned to the cabin with the EVA crewmember. Two second generation suitports were designed and tested. The previously reported second generation Marman Clamp suitport and a newer concept, the Pneumatic Flipper Suitport. These second generation suitports demonstrated human donning and doffing of the Z1 spacesuit with an 8.3 psi pressure differential across the spacesuit. Testing was performed using the JSC B32 Chamber B, a human rated vacuum chamber. The test included human rated suitports, the suitport compatible prototype suit, and chamber modifications. This test brought these three elements together in the first ever pressurized donning of a rear entry suit through a suitport. This paper presents the results of the testing, including unexpected difficulties with doffing, and engineering solutions implemented to ease the difficulties. A review of suitport functions, including a discussion of the need to doff a pressurized suit in earth gravity, is included. Recommendations for future design and testing are documented.

  16. Electrostatic Clamp Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal addresses Topic X6.02, Space Assembly Maintenance and Servicing. Spacecraft surface attachments, such as handholds, foot-restraints or tether points...

  17. Patch-clamp capacitance measurements and Ca²⁺ imaging at single nerve terminals in retinal slices.

    Science.gov (United States)

    Kim, Mean-Hwan; Vickers, Evan; von Gersdorff, Henrique

    2012-01-01

    Visual stimuli are detected and conveyed over a wide dynamic range of light intensities and frequency changes by specialized neurons in the vertebrate retina. Two classes of retinal neurons, photoreceptors and bipolar cells, accomplish this by using ribbon-type active zones, which enable sustained and high-throughput neurotransmitter release over long time periods. ON-type mixed bipolar cell (Mb) terminals in the goldfish retina, which depolarize to light stimuli and receive mixed rod and cone photoreceptor input, are suitable for the study of ribbon-type synapses both due to their large size (~10-12 μm diameter) and to their numerous lateral and reciprocal synaptic connections with amacrine cell dendrites. Direct access to Mb bipolar cell terminals in goldfish retinal slices with the patch-clamp technique allows the measurement of presynaptic Ca(2+) currents, membrane capacitance changes, and reciprocal synaptic feedback inhibition mediated by GABA(A) and GABA(C) receptors expressed on the terminals. Presynaptic membrane capacitance measurements of exocytosis allow one to study the short-term plasticity of excitatory neurotransmitter release. In addition, short-term and long-term plasticity of inhibitory neurotransmitter release from amacrine cells can also be investigated by recordings of reciprocal feedback inhibition arriving at the Mb terminal. Over short periods of time (e.g. ~10 s), GABAergic reciprocal feedback inhibition from amacrine cells undergoes paired-pulse depression via GABA vesicle pool depletion. The synaptic dynamics of retinal microcircuits in the inner plexiform layer of the retina can thus be directly studied. The brain-slice technique was introduced more than 40 years ago but is still very useful for the investigation of the electrical properties of neurons, both at the single cell soma, single dendrite or axon, and microcircuit synaptic level. Tissues that are too small to be glued directly onto the slicing chamber are often first embedded

  18. Characterization of the torque limits and clamping force relationships for small stainless steel screws in tensile loaded joints of various metals

    Energy Technology Data Exchange (ETDEWEB)

    Bernardin, John D [Los Alamos National Laboratory; Flores, Eugene M [Los Alamos National Laboratory

    2009-01-01

    This study originated during the design of ChemCam, a Laser Induced Breakdown Spectroscopy (LIBS) and imaging instrument being developed for NASA's Mars Science Lab Rover. The mission needs for miniaturization, reduced weight, high reliability, minimal use of thread locking compounds, and the ability to handle harsh environmental conditions dictated the use of small, high strength screws to be threaded into a variety of metal alloys including Be-S200f, Al-6061-T6, Mg-ZK60A-T5, and Ti-6Al-4V The lack of a credible fastener torque database for small (No.0 through No.8) high strength stainless steel screws in various parent materials, led to the development of an experimental program to characterize the following: (A) The screw torque value versus angular rotation (which indicates yielding in the screw or parent material) as a function of screw diameter, screw head configuration, depth of thread engagement, type of parent material, type of surface treatment on parent material, presence of thread locking compound, repeatable threaded hole use, and degree of screw pedigree. (B) The relationship between fastener torque and clamping force for a subset of the above mentioned variables. The database generated from this study will serve as a design reference for utilizing small stainless steel fasteners and provide trending information for other researchers who may be interested in broadening its range of parameters. This paper reviews the related fastener torque and clamping force information from the literature, describes the experimental screw torque and clamping force monitoring equipment, presents the test matrix and experimental procedures, and discusses the empirical results.

  19. Ethanol inhibition of N-methyl-D-aspartate-activated current in mouse hippocampal neurones: whole-cell patch-clamp analysis

    OpenAIRE

    Peoples, Robert W.; White, Geoffrey; Lovinger, David M.; Weight, Forrest F

    1997-01-01

    The action of ethanol on N-methyl-D-aspartate (NMDA)-activated ion current was studied in mouse hippocampal neurones in culture using whole-cell patch-clamp recording.Ethanol inhibited NMDA-activated current in a voltage-independent manner, and did not alter the reversal potential of NMDA-activated current.Concentration–response analysis of NMDA- and glycine-activated current revealed that ethanol decreased the maximal response to both agonists without affecting their EC50 values.The polyamin...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    In this paper, a modulation strategy based on the circuit-level decoupling concept is proposed and investigated for the three-level four-leg neutral-point-clamped (NPC) inverter,with the aim of delivering power to all sorts of loads, linear/nonlinear and balanced/unbalanced. By applying the propo...... 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....

  1. An experimental study on the changes of the doppler patterns in the common carotid artery after clamping of the internal carotid artery

    International Nuclear Information System (INIS)

    Recently, duplex sonography has been used as a screening test for the evaluation of carotid arterial disease. If an occlusion of atherosclerosis is located at the bifurcation of the common carotid artery or the lower portion of the internal carotid artery, the luminal change may be directly visualized on high-resolution B-mode sonography or color-Doppler images. But when the lesion is located at the high cervical, petrous or cavernous protion of the internal carotid artery, it is difficult to directly visualize the lesion with the sonography. The purpose of this paper is to evaluate the indirect changes on the Doppler patterns of both common carotid arteries with clamping of an internal carotid artery. Thirty common carotid arteries in fifteen normal rabbits were examined with duplex ultrasonography using high-resolution real-time imaging and 7.5MHz pulsed-wave Doppler flow measurements with velocity waveform analysis. Systolic velocity (SV) was 45.4 ± 8.4cm/sec, end-diastolic velocity (EDV) 15.3 ± 4.9cm/sec and resistative index (RI) 0.66 ± 0.08 in the common carotid artery before clamping of the internal carotid artery. SV was 26.3 ± 7.8cm/sec, EDV 6.0 ± 5.2cm/sec and RI 0.78 ± 0.18 in the ipsilateral common carotid artery and SV was 56.6 ± 13.0cm/sec, EDV 22.3 ± 8.2cm/sec and RI 0.61 ± 0.10 in the contralateral common carotid artery after clamping of the internal carotid artery. During clamping of the internal carotid artery, the difference between SV of bilateral common carotid arteries was 30.3 ± 13.8cm/sec and EDV 16.3 ± 9.2cm/sec. There was no difference of the velocity patterns of the common carotid artery between preclamping and declamping of the internal carotid artery. In conclusion, lower SV and EDV in a common carotid artery than that in contralateral side on Doppler patterns strongly suggests an occlusion of ipsilateral internal carotid artery

  2. A cross-sectional characterization of insulin resistance by phenotype and insulin clamp in East Asian Americans with type 1 and type 2 diabetes.

    Directory of Open Access Journals (Sweden)

    William C Hsu

    Full Text Available OBJECTIVE: Classic features of type 1 and type 2 diabetes may not apply in Asian Americans, due to shared absence of common HLA DR-DQ genotype, low prevalence of positive anti-islet antibodies and low BMI in both types of diabetes. Our objective was to characterize diabetic phenotypes in Asian Americans by clamp and clinical features. MATERIALS/METHODS: This was a cross-sectional study conducted in a referral center. Thirty East young Asian American adult volunteers (27.6±5.5 years with type 1, type 2 diabetes or controls underwent hyperinsulinemic euglycemic clamp to assess insulin resistance and DEXA to assess adiposity. RESULTS: Gender, BMI, waist/hip ratio, leptin, LDL, anti-GAD, anti-IA2 antibodies and C-reactive protein were similar among three groups. Serum C-peptide, adiponectin, free fatty acid, HDL concentrations and truncal fat by DEXA, were different between diabetic groups. Glucose disposal rate by clamp was lowest in type 2 diabetes, followed by type 1 diabetes and controls (5.43±2.70, 7.62±2.59, 8.61±2.37 mg/min/kg, respectively, p = 0.001. Free fatty acid concentration universally plummeted during steady state of the clamp procedure regardless of diabetes types in all three groups. Adipocyte fatty acid binding protein in the entire cohort (r = -0.625, p = 0.04 and controls (r = -0.869, p = 0.046 correlated best with insulin resistance, independent of BMI. CONCLUSIONS: Type 2 diabetes in Asian Americans was associated with insulin resistance despite having low BMI as type 1 diabetes, suggesting a potential role for targeting insulin resistance apart from weight loss. Adipocyte fatty acid binding protein, strongly associated with insulin resistance, independent of adiposity in the young Asian American population, may potentially serve as a biomarker to identify at-risk individuals. Larger studies are needed to confirm this finding.

  3. Effects of Protein Kinase C on the L-Type Ca2+ Channel in Single Rabbit Sino-Atrial Nodal Cells : Analysis by Patch-Clamp Technique

    OpenAIRE

    Satoh, Hiroyasu; 佐藤, 広康

    1994-01-01

    Efects of phorbol esters (stimulator of protein kinase C) on the L-type Ca^2+ current in isolated single rabbit sino-atrial (SA) nodal cells were examined. In whole-cell voltage-clamp experiments, 12-0-tetradecanoylphorbo1-13-acetate (TPA) at 10^-7 M inhibited the L-type Ca^2+ current. Pretreatment with H-7 (10^-5 M), an antagonist of protein kinase C (PK-C), did not modify the TPA-induced depression. The time course of inactivation process for the L-type Ca^2 current was slowed. In cell-atta...

  4. A Novel Scheme for Reduction of Torque Ripple in Direct Torque Control of Three Phase Squirrel Cage Induction Motor Using Seven Level Neutral Point Clamped Inverter

    Directory of Open Access Journals (Sweden)

    S. Priya

    2013-02-01

    Full Text Available Direct torque control of a 3 phase squirrel cage Induction motor though offers a good dynamic response and is free from dynamic coordinate transformation has a major disadvantage of producing rippled torque which degrades the performance of entire drive system. A scheme is proposed in this study which employs seven levels Neutral point clamped inverter which helps in alleviating the torque disturbances. The control scheme for the proposed method is described in this study and the simulation results are reported to demonstrate its effectiveness.

  5. Vibrations of an Elastic Orthotropic Unmoment Open Cylindrical Shell with Variable Curvature and Free End, when Other Edges are Rigid–Clamped

    Directory of Open Access Journals (Sweden)

    Ghulghazaryan G.R.

    2011-03-01

    Full Text Available The problem of existence of free vibrations of an elastic orthotropic open cylindrical shell (with arbitrary directional curve with free end, when other edges are rigid – clamped is studied. The investigation is carried out for elastic orthotropic shell when bending rigidity is vanishingly small (the moment free shell. The dispersion equations for finding the natural frequencies of vibrations are derived. The calculations were carried out for the shells with directing curve in form of a parabola with different values of curvature and lengths.

  6. Structural Optimization of CT Clamping Block on Injection Head%连续管注入头夹持块结构优化研究

    Institute of Scientific and Technical Information of China (English)

    李现东; 文涛

    2012-01-01

    Injector head is the main device of coiled tubing (CT) equipment which controls CT upstrain and injection. Clamping block is the key part for direct contact between injector head and CT. The clamping block with a reasonable structure must do relatively less harm to CT. Taking as the object of study the contact model of clamping block and CT, this paper explores the variation law of structural parameters of the block and stress and deformation of CT. The research findings show that the circular-arc structure adopted by the block can reduce damage to CT. The combined design of the circular-arc block can shorten the replacement time. When the circumferential wrap angle of the block is between 160° and 175° and the inner diameter is between 88.75 mm and 88.90 mm, the stress and deformation of CT are desirable. The clamping capacity of the block is strong and the desirable optimization effect can be achieved.%注入头是连续管装备中控制连续管上提和下注的主要装置,而夹持块是注入头与连续管直接接触的关键部件,结构合理的夹持块不仅能满足注入头作业质量要求,而且对连续管的伤害也较小。以夹持块和连续管的接触模型为研究对象,探索夹持块结构参数与连续管应力和变形之间的变化规律。研究结果表明,夹持块采用圆弧形结构可减轻对连续管的伤害,圆弧形夹持块的组合式设计可缩短其更换而造成的停工时间;当夹持块圆周包角在160°-175°、内径在88.75—88.90mm范围内取值时,连续管的应力和变形情况均较好,夹持块的夹持能力也较强,能够收到较好的优化效果。

  7. The Design of an Asic Control Chip for a Forward Active Clamp Converter and the Investigation of Integratable Lateral Power Devices

    OpenAIRE

    Dong, Wei

    1997-01-01

    In Part I, the design of an ASIC control chip for a forward active clamp converter is presented. Integration of the control and drive circuit into one IC chip results in higher power density, higher reliability for the converter module. The designed ASIC control chip uses a 2.0 um N well Analog CMOS process, and is fabricated at MOSIS. The design procedures of the ASIC chip are explained, and experimental results are presented. Part II of the thesis focuses on the numerical investigat...

  8. Optimization Design of Clamping Teeth of Offshore Discarded Platform Piles Removal Wire Saw%海洋废弃平台桩基拆除绳锯机夹紧齿优化设计研究

    Institute of Scientific and Technical Information of China (English)

    王海波; 张岚; 孟庆鑫; 王

    2014-01-01

    海洋废弃平台桩基拆除绳锯机是一种近年发展起来的新型水下作业机具,它主要由绳锯机本体和液压控制系统构成,绳锯机夹紧瓣上的夹紧齿可以使绳锯机安全、稳定地工作。介绍了夹紧齿的结构,分析得到了夹紧齿尺寸和齿周过渡曲线的优化数学模型,采用有限元法优化得到了夹紧齿关键参数。根据优化结果设计制造了夹紧齿,实验结果表明:该夹紧齿能够满足要求,为绳锯机的安全稳定工作打下了一定的基础。%Offshore discarded platform piles removal wire saw is a new underwater work tools which is developed in recent years. Its main structure includes the wire saw body and a hydraulic control system,the clamping teeth of clamping flap can make wire saw safely and stably work. Clamping teeth structure was described,the optimization mathematical models of clamping tooth size and tooth transition curve were obtained by analyzing,and the clamping tooth key optimization parameters were derived using the finite element method. Clamping teeth was designed and manufactured according to the optimization results. The experiment result shows that the clamping teeth is able to meet the requirements,which lays foundation for the security and stability of the wire saw.

  9. Primary Ressction and Ring Clamp Crushing Anastomosis for Hirschsprung's Ditease in Newborns%环钳斜吻合法治疗新生儿巨结肠

    Institute of Scientific and Technical Information of China (English)

    陈幼容

    1989-01-01

    1978 to 1986,primary resection and ring clamp crushing anastomosis performed on 48 cases of long segment aganglionic Hirsehsprung's disease in newborns failed to respond the anal dilatation and rectal irrigation treatment.The total mortality was 6.3%.2 patients died of residual infections and the other one had recurrent distention being given up by the parents.In mostcases,the ring clamp dislodged spontaneously in 6-7 days after operation.Postoperative analdilatation by the parents began in 2 weeks and kept on at least 6 months for bowel training.42 cases(93%)were followed up for morethan one year and good results were obtained indicated by mormal growth and good nutriture,no distention of abdomen,no stenosis or blind pouch in the rectum.The advantages of this operation are:a shorter operation time(90-120min),less hemorrage(20-30mi),less operative trauma,and least peritoneal contamination.%本院1978~1986年使用环钳斜吻合法作一期根治手术治疗新生儿巨结肠48例.本文主要介绍该方法的操作及手术中的注意事项.

  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. PMID:5823216

  11. 注塑机锁模机构动力学模型的建立与验证%Construction and Verification of Kinetics Model of Clamping System for Injection Molding Machine

    Institute of Scientific and Technical Information of China (English)

    王建康; 张涛; 黄汉雄; 刘向阳; 黎秀郁

    2011-01-01

    对双曲肘五铰点锁模装置进行动力学分析,建立数学模型,并利用实验法确定该机构的传动损失因子.利用该模型对某系列注塑机的锁模力和锁模行程进行预测,并与实际值进行比较,结果显示的锁模力预测误差在3%以内,锁模行程的预测误差在0.12%以内.%An analysis on motional and mechanical characteristics of double-toggle clamping unit with slanting-five points for injection molding machine was made. The mathematical model used to predict clamping force and mold platen travel distance was constructed. The total transmitting efficiency factor of clamping system was determined using experimental method. By comparing the predicted and real value of clamping force, mold platen travel distance, it showed the errors of predicted clamping force and mold platen travel distance were within in 3%, and 1.2 ‰, respectively.

  12. Pinching of PE pipes - Compilation report on standards, practices and experiences of clamping of PE gas pipes; Klaemning av PE-roer - Sammanstaellande rapport oever standarder, rutiner och erfarenheter kring klaemning av PE-gasroer

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-09-15

    Pinching is one method used to control or shut off the flow in a gas pipe. The pinching tool squeezes the tube with two round rods until the tube inner walls meet. The report present collected experiences and practices regarding clamping of Polyethylene (PE) tubes. The focus has been primarily to gather information regarding clamping of PE tubes with diameters greater than 160 mm and coated tubes (tube with the protective coating). The information presented in the report was mainly gathered through e-mail and phone contact with the gas company and tube manufacturers, but also organizations and consultancies have contacted. The information from each participant is reported separately as procedures and standards in clamping of PE pipes differ between countries and actors.

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

    Science.gov (United States)

    Lewan, Michael D.; Birdwell, Justin E.

    2013-01-01

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

  14. Influence of Clamps on Un-crimped Energy Testing Results of Cigarette Tow%夹板对烟用丝束未卷曲能检测结果的影响

    Institute of Scientific and Technical Information of China (English)

    张丕锐; 严锐; 孟华

    2012-01-01

    二醋酸纤维素丝束未卷曲能是丝束生产控制的重要工艺指标之一,其检测数据的可靠准确对指导控制工艺、保障丝束质量非常重要。采用梯形夹板、正弦波夹板对丝束未卷曲能数值进行检测,不同夹板获得的丝束未卷曲能数值存在明显差异;采用Mini-tab分析了未卷曲能数值稳定性的差异,选出了合适的夹板模式。结果表明:采用正弦波夹板检测丝柬未卷曲能更为可靠稳定。%Un-crimped energy is one of important parameters in cellulose acetate cigarette tow production. The reliable and stable testing data is very important to process control and tow quality. Different test results were obtained by application of different clamps including trapezia and sine shaped clamps. Testing results have been showed that the clamp significantly impacts the testing results of un-crimped energy. Mini--tab was used to analysis the standard deviation under the application of different clamps. Suitable clamp was selected to decrease the fluctuation in testing. More reliable and stable testing results were gotten by sine shaped clamp application.

  15. Effect of delayed cord clamping in term infants:a meta-analysis%延迟脐带结扎对足月儿影响的meta分析

    Institute of Scientific and Technical Information of China (English)

    余章斌; 韩树萍; 沙莉; 董小玥; 陈玉林; 邱玉芳

    2014-01-01

    目的:评价延迟脐带结扎(DCC)对足月儿的影响。方法检索Cochrane图书馆、PubMed、EMBASE、中国知网、维普、万方数据库,检索时间均从1970年1月起至2013年4月;对纳入文献进行质量评价,并采用RevMan 5.1.0软件进行meta分析。结果共纳入10篇文献,总样本量为1623例。Meta分析结果显示,与立即结扎脐带相比,DCC可以明显提高足月儿出生后血红蛋白的水平(MD=2.19,95%CI:0.36~4.02),对足月儿6个月内血红蛋白的水平没有影响(MD=0.29,95%CI:-0.17~0.75),对足月儿6个月内贫血的发生率没有影响(RR=0.71,95%CI:0.45~1.12),但增加足月儿出生后红细胞增多症的发生率(RR=2.87,95%CI:1.24~6.62),对于高胆红素血症光疗没有影响(RR=2.46,95%CI:0.93~6.52)。结论DCC能改善足月儿出生后的血红蛋白水平;但关于合适的延长时间没有研究进行评价,需要进一步开展高质量、大样本随机对照试验评价合适的DCC的时间。%Objective To systematically evaluate the effectiveness of delayed cord clamping (DCC) in term infants. Methods The data of the Cochrane library, PubMed, EMBASE, CNKI , VIP, Wanfang from 1 January 1970 to 30 April 2013 were searched. Randomized controlled trials (RCT) of DCC in term infants were included.RevMan 5.1.0 was used in the statis-tical analysis. Results Ten studies involving 1623 participants were included. Meta-analysis based on included studies showed that:compared with immediate cord clamping (ICC), DCC improved the hemoglobin levels at birth (MD=2.19, 95%CI:0.36, 4.02) and increased the incidence of polycythaemia (RR=2.87, 95%CI:1.24, 6.62). Compared with ICC, DCC showed no signi-ficant difference in the phototherapy for hyperbilirubinemia (RR=2.46, 95%CI: 0.93, 6.52), the hemoglobin levels within 6 months (MD=0.29, 95%CI:-0.17, 0.75), and the incidence of anemia (RR=0.71, 95%CI:0.45, 1.12). Conclusions DCC can improve

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

    DEFF Research Database (Denmark)

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

    A Neutral-Point-Clamped (NPC) three-level inverter with small DC-link capacitors is presented in this paper. This inverter requires zero average neutral-point current for stable neutral-point potential. A simple carrier based modulation strategy is proposed for achieving zero average neutral......-point current. A new simplified model of the neutral-point voltage dynamics is derived for the proposed modulation strategy. This model shows that the neutral-point current is proportional to the power drawn from the converter and it enables the use of well established classical control theory for neutral......-point voltage controller design. A PI controller is used for neutral-point voltage balance. The implementation of the proposed modulation strategy and controller is simple. It does not require any information about the output phase currents. The controller is implemented in a 7.5 kW induction machine based...

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

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2012-01-01

    investigates the loss and thermal performances of a 10 MW 3L-NPC wind power inverter undergoing Low Voltage Ride Through (LVRT) operation. A series of new space vector modulation methods are then proposed to relocate the thermal loading among the power switching devices. It is concluded that, with the proposed......The three-level neutral-point-clamped (3L-NPC) converter is a promising multilevel topology in the application of mega-watts wind power generation system. However, the growing requirements by grid codes may impose high stress and even give reliability problem to this converter topology. This paper...... modulation methods, the thermal distribution in the 3L-NPC wind power inverter undergoing LVRT becomes more equal, and the junction temperature of the most stressed devices can be also relieved. Also the control ability of DC-bus neutral point potential, which is one of the crucial considerations for the 3L...

  18. 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

    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 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...... 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...

  19. How to Save the Two Clamping String of Bozhou%如何拯救“亳州二夹弦”

    Institute of Scientific and Technical Information of China (English)

    洪仁国; 陈永红

    2011-01-01

    作为悠久历史、极具艺术价值的地方剧种,"亳州二夹弦"正面临濒临灭绝的境地。探究"亳州二夹弦"的发展历程与音乐特点,实地调查其生存现状,问寻拯救之道,不仅是保存、发展传统文化的应有之义,也是丰富现代文化的必要手段。%Having a highly artistic value of drama and a long history,the two clamping string of Bozhou is facing extinction.To study its history and music features,to investigate its living situation,and to save it,is not only to preserve the traditional culture,but also to enrich the modern culture.

  20. In vivo patch-clamp analysis of response properties of rat primary somatosensory cortical neurons responding to noxious stimulation of the facial skin

    Directory of Open Access Journals (Sweden)

    Nasu Masanori

    2010-05-01

    Full Text Available Abstract Background Although it has been widely accepted that the primary somatosensory (SI cortex plays an important role in pain perception, it still remains unclear how the nociceptive mechanisms of synaptic transmission occur at the single neuron level. The aim of the present study was to examine whether noxious stimulation applied to the orofacial area evokes the synaptic response of SI neurons in urethane-anesthetized rats using an in vivo patch-clamp technique. Results In vivo whole-cell current-clamp recordings were performed in rat SI neurons (layers III-IV. Twenty-seven out of 63 neurons were identified in the mechanical receptive field of the orofacial area (36 neurons showed no receptive field and they were classified as non-nociceptive (low-threshold mechanoreceptive; 6/27, 22% and nociceptive neurons. Nociceptive neurons were further divided into wide-dynamic range neurons (3/27, 11% and nociceptive-specific neurons (18/27, 67%. In the majority of these neurons, a proportion of the excitatory postsynaptic potentials (EPSPs reached the threshold, and then generated random discharges of action potentials. Noxious mechanical stimuli applied to the receptive field elicited a discharge of action potentials on the barrage of EPSPs. In the case of noxious chemical stimulation applied as mustard oil to the orofacial area, the membrane potential shifted depolarization and the rate of spontaneous discharges gradually increased as did the noxious pinch-evoked discharge rates, which were usually associated with potentiated EPSP amplitudes. Conclusions The present study provides evidence that SI neurons in deep layers III-V respond to the temporal summation of EPSPs due to noxious mechanical and chemical stimulation applied to the orofacial area and that these neurons may contribute to the processing of nociceptive information, including hyperalgesia.

  1. Efeitos do clampeamento do pedículo hepático nos intestinos Effects of the clamping of the hepatic pedículo in the intestines

    Directory of Open Access Journals (Sweden)

    Abrão Antonio Sébe

    2000-03-01

    Full Text Available Foi realizado clampeamento do pedículo hepático de rato por diferentes tempos e estudadas as repercussões nos intestinos. Para tanto foram utilizados 40 ratos, machos, divididos em quatro grupos de 10 animais cada. O grupo S (Sham não foi submetido a isquemia, já os grupos E1, E2 e E3 sofreram isquemia de 10, 20 e 30 minutos respectivamente. Nossos resultados mostraram alterações macroscópicas quanto a cor dos intestinos nos grupos E2 (20' e E3 (30' e histopatológicas que ocorreram em cada um desses grupos. Observou-se que quanto maior o tempo de clampeamento do pedículo hepático, maior a congestão esplâncnica, sendo que aos 30 minutos ocorreu o despreendimento do revestimento epitelial das vilosidades intestinais e hemorragia.It was made a clamping of the hepatic pedicle in different lapses of time and the morphological features of this intestines were observed. 40 male rats were divided in four groups of 10 animals each. The group S (Sham was not submitted to ischemia and the groups E1, E2 and E3 suffered ischemia during 10, 20 and 30 minutes respectively. Our results showed macroscopic modifications related to the colour of the intestines in the groups E2 (20' and E3 (30' as well as histopathological changes in the same groups. It was also observed that the larger the lapse of time of clamping of the hepatic pedicle the larger was the splanchnic congestion and in the group 30' detachment of the lining epithelium was observed in the intestinal villi.

  2. Precise control of clamping force for watermelon picking end-effector%西瓜采摘末端执行器夹持力精确控制

    Institute of Scientific and Technical Information of China (English)

    胡志勇; 张学炜; 张伟; 王琳

    2014-01-01

    为实现西瓜的机械化采摘,该文提出了采用液压驱动型末端执行器采摘大型果实的思路。在抓取西瓜时,为避免末端执行器夹持力不稳定引起的果实损伤,需对夹持力进行精确控制,该文建立了末端执行器负载模拟平台和AMESim&Simulink联合仿真模型,模拟西瓜采摘夹持力的加载情况。针对执行器夹持力加载过程中位置控制系统对力控制系统产生干扰,影响夹持力精确加载的问题,该文基于速度同步控制原理,设计了简化的加载误差补偿环节,开展了加载误差补偿理论、仿真及试验研究。结果表明,速度同步控制方法能够有效地减小加载误差,提高末端执行器负载模拟精度。该研究可为末端执行器输出力的精确控制和抓取控制策略提供参考。%Certain agricultural work requires a very stable robot end-effector to reduce vibration and damage to products. However, the structures of conventional articulated robots tend to be too weak to manipulate heavy objects, such as the watermelon. To achieve mechanized harvesting of the watermelon, we compared the characteristics of different end-effectors with the motor, pneumatic and hydraulic drives. By contrast, the hydraulic drive has many advantages, such as high power-weight ratio, compact structure and convenient layout. Therefore, the end-effector with hydraulic drive is more suitable for heavy fruit harvesting such as the watermelon. The hydraulic drive system based on force perception can output appropriate clamping force according to actual situation. When picking robot crawls and picks, it needs to avoid the damage to fruits and vegetables caused by unstable clamping force and to achieve the precise control of the clamping force for picking robot end-effector. Therefore, how to improve output force’s control precision of the valve control cylinder and reduce interference are key to improve the picking performance. Two

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

    Institute of Scientific and Technical Information of China (English)

    陶表达

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2015-06-01

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

  5. 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

  6. Comparison of Global Model Results from the Carbon-Land Model Intercomparison Project (C-LAMP) with Free-Air Carbon Dioxide Enrichment (FACE) Manipulation Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Forrest M [ORNL; Randerson, Jim [University of California, Irvine; Fung, Inez [University of California, Berkeley; Thornton, Peter E [ORNL; Covey, Curtis [Lawrence Livermore National Laboratory (LLNL); Bonan, Gordon [National Center for Atmospheric Research (NCAR); Running, Steven [University of Montana, Missoula; Norby, Richard J [ORNL

    2008-01-01

    Free-Air CO{sub 2} Enrichment (FACE) manipulation experiments have been carried out at a handful of sites to gauge the response of the biosphere to significant increases in atmospheric [CO{sub 2}]. Early synthesis results from four temperate forest sites suggest that the response of net primary productivity (NPP) is conserved across a broad range of productivity with a stimulation at the median of 23 {+-} 2% when the surrounding air [CO{sub 2}] was raised to 550{approx}ppm. As a part of the Carbon-Land Model Intercomparison Project (C-LAMP), a community-based model-data comparison activity, the authors have performed a global FACE modeling experiment using two terrestrial biogeochemistry modules, CLM3-CASA and CLM3-CN, coupled to the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM). The two models were forced with an improved NCEP/NCAR reanalysis data set and reconstructed atmospheric [CO{sub 2}] and N deposition data through 1997. At the beginning of 1997 in the transient simulations, global atmospheric [CO{sub 2}] was abruptly raised to 550{approx}ppm, the target value used at the FACE sites. In the control runs, [CO{sub 2}] continued to rise following observations until 2004, after which it was held constant out to year 2100. In both simulations, the last 25 years of reanalysis forcing and a constant N deposition were applied after year 2004. Across all forest biomes, the NPP responses from both models are weaker than those reported for the four FACE sites. Moreover, model responses vary widely geographically with a decreasing trend of NPP increases from 40{sup o}N to 70{sup o}N. For CLM3-CASA, the largest responses occur in arid regions of western North America and central Asia, suggesting that responses are most strongly influenced by increased water use efficiency for this model. CLM3-CN exhibits consistently weaker responses than CLM3-CASA' with the strongest responses in central Asia, but significantly constrained

  7. Ipsilateral common iliac artery plus femoral artery clamping for inducing sciatic nerve ischemia/reperfusion injury in rats: a reliable and simple method

    Directory of Open Access Journals (Sweden)

    Barzegar-Fallah Anita

    2008-12-01

    Full Text Available Abstract The aim of this study was to develop a practical model of sciatic ischemia reperfusion (I/R injury producing serious neurologic deficits and being technically feasible compared with the current time consuming or ineffective models. Thirty rats were divided into 6 groups (n = 5. Animal were anesthetized by using ketamine (50 mg/kg and xylazine (4 mg/kg. Experimental groups included a sham-operated group and five I/R groups with different reperfusion time intervals (0 h, 3 h, 1 d, 4 d, 7 d. In I/R groups, the right common iliac artery and the right femoral artery were clamped for 3 hrs. Sham-operated animals underwent only laparotomy without induction of ischemia. Just before euthanasia, behavioral scores (based on gait, grasp, paw position, and pinch sensitivity were obtained and then sciatic nerves were removed for light-microscopy studies (for ischemic fiber degeneration (IFD and edema. Behavioral score deteriorated among the ischemic groups compared with the control group (p

  8. The initiation factor TFE and the elongation factor Spt4/5 compete for the RNAP clamp during transcription initiation and elongation.

    Science.gov (United States)

    Grohmann, Dina; Nagy, Julia; Chakraborty, Anirban; Klose, Daniel; Fielden, Daniel; Ebright, Richard H; Michaelis, Jens; Werner, Finn

    2011-07-22

    TFIIE and the archaeal homolog TFE enhance DNA strand separation of eukaryotic RNAPII and the archaeal RNAP during transcription initiation by an unknown mechanism. We have developed a fluorescently labeled recombinant M. jannaschii RNAP system to probe the archaeal transcription initiation complex, consisting of promoter DNA, TBP, TFB, TFE, and RNAP. We have localized the position of the TFE winged helix (WH) and Zinc ribbon (ZR) domains on the RNAP using single-molecule FRET. The interaction sites of the TFE WH domain and the transcription elongation factor Spt4/5 overlap, and both factors compete for RNAP binding. Binding of Spt4/5 to RNAP represses promoter-directed transcription in the absence of TFE, which alleviates this effect by displacing Spt4/5 from RNAP. During elongation, Spt4/5 can displace TFE from the RNAP elongation complex and stimulate processivity. Our results identify the RNAP "clamp" region as a regulatory hot spot for both transcription initiation and transcription elongation. PMID:21777815

  9. Analysis of ultrasound propagation in high-temperature nuclear reactor feedwater to investigate a clamp-on ultrasonic pulse doppler flowmeter

    International Nuclear Information System (INIS)

    The flow rate of nuclear reactor feedwater is an important factor in the operation of a nuclear power reactor. Venturi nozzles are widely used to measure the flow rate. Other types of flowmeters have been proposed to improve measurement accuracy and permit the flow rate and reactor power to be increased. The ultrasonic pulse Doppler system is expected to be a candidate method because it can measure the flow profile across the pipe cross section, which changes with time. For accurate estimation of the flow velocity, the incidence angle of ultrasound entering the fluid should be estimated using Snell's law. However, evaluation of the ultrasound propagation is not straightforward, especially for a high-temperature pipe with a clamp-on ultrasonic Doppler flowmeter. The ultrasound beam path may differ from what is expected from Snell's law due to the temperature gradient in the wedge and variation in the acoustic impedance between interfaces. Recently, simulation code for ultrasound propagation has come into use in the nuclear field for nondestructive testing. This article analyzes and discusses ultrasound propagation, using 3D-FEM simulation code plus the Kirchhoff method, as it relates to flow profile measurement in nuclear reactor feedwater with the ultrasonic pulse Doppler system. (author)

  10. Influence of misonidazole, anaesthesia, clamping of the leg and stress of the animal during treatment on the radiation-induced skin reaction of mouse feet

    International Nuclear Information System (INIS)

    The influence of anaesthesia and misonidazole on the 'acute' (average of the scores between day 10 and 30) and 'late' (average of the scores between day 100 and 120) skin reaction of the feet of mice was investigated under two different conditions. Firstly, the legs were kept untaped in the radiation field; secondly, the legs were fixed with surgical tape on the backscatter block. Irradiation was carried out by X-radiation at a dose of 35 Gy. Results showed that stress in unanaesthetized animals has a large influence on the radiation response of mouse skin. Adequate treatment conditions, tranquillizers or anaesthesia can compensate for this factor. Taping of the animals' legs, resulting in clamping, interferes with the assessment of these modalities. No influence of misonidazole on the skin reaction could be demonstrated in conditions where no artificial hypoxia was induced. The importance of taking experimental conditions into account is pointed out for the correct assessment of the effect of radiosensitizers and possibly other anticancer drugs. (U.K.)

  11. Effects of deuterium oxide on the rate and dissociation constants for saxitoxin and tetrodotoxin action. Voltage-clamp studies on frog myelinated nerve

    International Nuclear Information System (INIS)

    The actions of tetrodotoxin (TTX) and saxitoxin (STX) in normal water and in deuterium oxide (D20) have been studied in frog myelinated nerve. Substitution of D20 for H20 in normal Ringer's solution has no effect on the potency of TTX in blocking action potentials but increases the potency of STX by approximately 50%. Under voltage clamp, the steady-state inhibition of sodium currents by 1 nM STX is doubled in D20 as a result of a halving of the rate of dissociation of STX from the sodium channel; the rate of block by STX is not measurably changed by D20. Neither steady-state inhibition nor the on- or off-rate constants of TTX are changed by D20 substitution. The isotopic effects on STX binding are observed less than 10 min after the toxin has been added to D20, thus eliminating the possibility that slow-exchange (t 1/2 greater than 10 h) hydrogen-binding sites on STX are involved. The results are consistent with a hypothesis that attributes receptor-toxin stabilization to isotopic changes of hydrogen bonding; this interpretation suggests that hydrogen bonds contribute more to the binding of STX than to that of TTX at the sodium channel

  12. Events leading to the opening and closing of the exocytotic fusion pore have markedly different temperature dependencies. Kinetic analysis of single fusion events in patch-clamped mouse mast cells.

    OpenAIRE

    Oberhauser, A F; Monck, J R; Fernandez, J.M.

    1992-01-01

    The earliest event in exocytosis is the formation of a fusion pore, an aqueous channel that connects the lumen of a secretory granule with the extracellular space. We can observe the formation of individual fusion pores and their subsequent dilation or closure by measuring the changes in the admittance of patch-clamped mast cells during GTP gamma S-stimulated exocytotic fusion. To investigate the molecular structure of the fusion pore, we have studied the temperature dependency of the rate co...

  13. Effect of end-tidal CO2 clamping on cerebrovascular function, oxygenation, and performance during 15-km time trial cycling in severe normobaric hypoxia: the role of cerebral O2 delivery.

    Science.gov (United States)

    Fan, Jui-Lin; Bourdillon, Nicolas; Kayser, Bengt

    2013-08-01

    During heavy exercise, hyperventilation-induced hypocapnia leads to cerebral vasoconstriction, resulting in a reduction in cerebral blood flow (CBF). A reduction in CBF would impair cerebral O2 delivery and potentially account for reduced exercise performance in hypoxia. We tested the hypothesis that end-tidal Pco2 (PETCO2) clamping in hypoxic exercise would prevent the hypocapnia-induced reduction in CBF during heavy exercise, thus improving exercise performance. We measured PETCO2, middle cerebral artery velocity (MCAv; index of CBF), prefrontal cerebral cortex oxygenation (cerebral O2Hb; index of cerebral oxygenation), cerebral O2 delivery (DO2), and leg muscle oxygenation (muscle O2Hb) in 10 healthy men (age 27 ± 7 years; VO2max 63.3 ± 6.6 mL/kg/min; mean ± SD) during simulated 15-km time trial cycling (TT) in normoxia and hypoxia (FIO2 = 0.10) with and without CO2 clamping. During exercise, hypoxia elevated MCAv and lowered cerebral O2Hb, cerebral DO2, and muscle O2Hb (P exercise in both normoxic and hypoxic conditions (P effect on either cerebral and muscle O2Hb (P = 0.118 and P = 0.124). Nevertheless, CO2 clamping elevated cerebral DO2 during TT in both normoxic and hypoxic conditions (P hypoxia and tended to have a greater effect on TT performance in hypoxia compared to normoxia (P = 0.097). However, post hoc analysis revealed no effect of CO2 clamping on TT performance either in normoxia (P = 0.588) or in hypoxia (P = 0.108). Our findings confirm that the hyperventilation-induced hypocapnia and the subsequent drop in cerebral oxygenation are unlikely to be the cause of the reduced endurance exercise performance in hypoxia. PMID:24303142

  14. 基于LM5025的有源箝位反激变换器的前馈控制%Feed-Forward Control of the Active Clamp Flyback Converters Based on LM5025

    Institute of Scientific and Technical Information of China (English)

    雷明; 程善美; 于孟春; 申勇哲

    2012-01-01

    在有源箝位反激变换器负载基本恒定的情况下采用前馈控制既可以减小变换器体积,又可降低变换器的成本。文中在分析有源箝位反激变换器工作原理的基础上,结合LM5025器件的前馈控制特性,深入研究了基于LM5025的有源箝位反激变换器前馈控制的实现方案,设计了前馈控制电路的参数,完成了有源前馈反激变换器电路设计。在此基础上进行了实验研究,实验结果证明了有源箝位反激变换器前馈控制的有效性和实用性。%Feed-forward control can both reduce the size of the converter volume and reduce the cost of the converter when the active clamp flyback converter load is almost constant. On the basis of the analysis of the active clamp flyback converter working principle, and combined with the feed-forward features of the LM5025 device, the implementation of feed-forward control used in active clamp flyback converter is deeply studied based on the LM5025, and the parameters of the feed-forward control circuit is designed, and the active feed forward flyback converter circuit is implemented. On this basis, the experimental study is earried, and the experimental results show the effectiveness and practicality of the feed-forward control of the active clamp flyback converter.

  15. Design of DC-DC converter with active clamp forward topology based on LM5026%基于LM5026的有源钳位正激DC-DC变换器设计

    Institute of Scientific and Technical Information of China (English)

    邱力军; 杨威; 王荣; 王伊笑

    2015-01-01

    In this paper the working principle of active clamp forward converter and the features of LM5026 chip were proposed. Furthermore, an example was proposed to discuss the design of transformer and inductor in active-clamp DC-DC converter. In the design example, efficiency of higher than 90%and the load regulation within 1%were obtained for an input of 28V and the implementation of the soft switch of the main MOSFET was realized, verifying the excellent load regulation and high efficiency of the active-clamp forward DC-DC converter.%介绍了有源钳位正激变换器的工作原理以及 LM5026芯片的功能特点,并以一个设计实例讨论了变压器和电感在有源钳位DC-DC变换器中的设计。结果表明,在28V 输入电压时,效率超过90%,负载调整率也在1%以内,且实现了主MOS管的软开通,验证了有源钳位正激变换器良好的负载调整率以及高效性。

  16. Development and validation of fluorescence-based and automated patch clamp-based functional assays for the inward rectifier potassium channel Kir4.1.

    Science.gov (United States)

    Raphemot, Rene; Kadakia, Rishin J; Olsen, Michelle L; Banerjee, Sreedatta; Days, Emily; Smith, Stephen S; Weaver, C David; Denton, Jerod S

    2013-01-01

    The inward rectifier potassium (Kir) channel Kir4.1 plays essential roles in modulation of neurotransmission and renal sodium transport and may represent a novel drug target for temporal lobe epilepsy and hypertension. The molecular pharmacology of Kir4.1 is limited to neurological drugs, such as fluoxetine (Prozac(©)), exhibiting weak and nonspecific activity toward the channel. The development of potent and selective small-molecule probes would provide critically needed tools for exploring the integrative physiology and therapeutic potential of Kir4.1. A fluorescence-based thallium (Tl(+)) flux assay that utilizes a tetracycline-inducible T-Rex-HEK293-Kir4.1 cell line to enable high-throughput screening (HTS) of small-molecule libraries was developed. The assay is dimethyl sulfoxide tolerant and exhibits robust screening statistics (Z'=0.75±0.06). A pilot screen of 3,655 small molecules and lipids revealed 16 Kir4.1 inhibitors (0.4% hit rate). 3,3-Diphenyl-N-(1-phenylethyl)propan-1-amine, termed VU717, inhibits Kir4.1-mediated thallium flux with an IC50 of ∼6 μM. An automated patch clamp assay using the IonFlux HT workbench was developed to facilitate compound characterization. Leak-subtracted ensemble "loose patch" recordings revealed robust tetracycline-inducible and Kir4.1 currents that were inhibited by fluoxetine (IC50=10 μM), VU717 (IC50=6 μM), and structurally related calcium channel blocker prenylamine (IC50=6 μM). Finally, we demonstrate that VU717 inhibits Kir4.1 channel activity in cultured rat astrocytes, providing proof-of-concept that the Tl(+) flux and IonFlux HT assays can enable the discovery of antagonists that are active against native Kir4.1 channels. PMID:24266659

  17. The flow-rate measurements in a multi-phase flow pipeline by using a clamp-on sealed radioisotope cross correlation flowmeter

    International Nuclear Information System (INIS)

    The flow rate measurements in a multi-phase flow pipeline were evaluated quantitatively by means of a clamp-on sealed radioisotope based on a cross correlation signal processing technique. The flow rates were calculated by a determination of the transit time between two sealed gamma sources by using a cross correlation function following FFT filtering, then corrected with vapor fraction in the pipeline which was measured by the γ-ray attenuation method. The pipeline model was manufactured by acrylic resin(ID. 8 cm, L=3.5 m, t=10 mm), and the multi-phase flow patterns were realized by an injection of compressed N2 gas. Two sealed gamma sources of 137Cs (E=0.662 MeV, Γ factor=0.326 R · h-1 · m2 · Ci-1) of 20 mCi and 17mCi, and radiation detectors of 2x 2NaI(TI) scintillation counter (Eberline, SP-3) were used for this study. Under the given conditions(the distance between two sources:4D(D; inner diameter), N/S ratio: 0.12∼0.15, sampling time Δt: 4msec), the measured flow rates showed the maximum, relative error of 1.7% when compared to the real ones through the vapor content corrections(6.1 % ∼ 9.2 %). From a subsequent experiment, it was proven that the closer the distance between the two sealed sources is, the more precise the measured flow rates are. Provided additional studies related to the selection of radioisotopes their activity, and an optimization of the experimental geometry are carried out, it is anticipated that a radioisotope application for flow rate measurements can be used as an important tool for monitoring multi-phase facilities belonging to petrochemical and refinery industries and contributes economically in the light of maintenance and control of them

  18. Assessing new homeostasis model assessment by Botnia clamp%利用Botnia钳夹试验评估新HOMA稳态模型

    Institute of Scientific and Technical Information of China (English)

    谢云; 李启富; 李宝毅; 冯静; 丘彦

    2009-01-01

    objective To investigate the ability of insulin sensitivity index HOMA2-%S and secretion function index HOMA2-%B calculated by HOMA2,the new homeostasis model assessment,in clinical application. Methods Eighty female volunteers with polycystic ovary syndrome in Chongqing area [50 subjects with normal glucose tolerance(NGT group)and 30 subjects with impaired glucose regulation(IGR group)]were involved in this study.Thev underwent a 75 g oral glucose tolerance test(OGTF)and the Botnia clamp test. From the data of faming blood samples in OGTF,insulin sensitivity index HOMAI-ISI,secretion function index HOMAl-β and disposal index DI-HOMA1 were calculated by the old homeostasis model assessment(HOMA I),meanwhile insulin sensitivity index HOMA2-%S,secretion function index HOMA2-%B and disposal index(DI-HOMA2) were caleulated by the new homeostasis model assessment (HOMA2).Correlation coefficients between insulin sensitivity index and GIR (the glucose infusion rate at steady state of Botnia clamp test),and between insulin secretion function index and AIR(the acute insulin response in Botnia clamp test),were studied.Results The Pearson's linear correlation coefficient between HOMA2-%S and GIR(r=0.503),HOMA1-ISI and HOMA2-%S (r= 0.990).HOMA2-%B and AIR(r=0.382),HOMA1-B and HOMA2-%B(r=0.976) were all statistically significant(a11 P<0.01).The glucose disposal indexes calculated from the HOMA2 and HOMA1 of 1GR group were significantly lower than those from the NGT group(t=2.825,P<0.Ol;t=2.222,P<0.05). Conclusion The HOMA2 is a better model in evaluating the insulin sensitivity and secretion function and is recommended to be widely used in clinical evaluation.%目的 研究新HOMA稳态模型(HOMA2)的胰岛素敏感性指数(HOMA2-%S)和分泌功能指数(HOMA2-%B)在临床中的应用价值.方法 利用80例重庆地区多囊卵巢综合征妇女[正常糖耐量(NGT)组50人,糖调节受损(IGR)组30人]的口服葡萄糖耐量试验和Botnia钳夹试验资

  19. A Study of Vascular Clamps on Crush Injury of Common Carotid Arteries in Rats%血管夹对大鼠颈总动脉挤压损伤的研究

    Institute of Scientific and Technical Information of China (English)

    余宽宽; 梁向党; 孙赓; 郭占芳; 邹秀强; 房卓群

    2015-01-01

    目的:探讨血管夹对大鼠颈总动脉的挤压损伤。方法将40只雄性SD大鼠随机分为两组,每组各20只,用改进后的血管夹分别对两组大鼠的左侧颈总动脉给予30 g和90 g的压力进行15 min的夹闭,右侧颈总动脉作为对照,术后正常饮食喂养3周。通过大体观察、超声血流检测、组织形态学观察、血管创伤评分对血管损伤情况进行评估。结果两组大鼠左侧颈总动脉损伤修复完好,超声血流通畅,HE染色内膜无明显损伤增生,与右侧颈总动脉比较血管创伤评分差异无统计学意义(P>0.05)。结论血管夹在血管吻合的过程中对血管的损伤不可避免,但这种仅因夹闭造成的暂时性损伤可通过自身修复。%Objective To explore vascular clamps on crush injury of common carotid arteries in rats. Methods A total of 40 SD male rats were randomly divided into group A and B ( n=20 for each group) , and left common carotid arteries of rats in group A and B were occluded using improved vascular clamps respectively under 30 g and 90 g pressure for 15 min, while the right common carotid arteries were used as comparison, all the rats were give normal postoperative feeding for 3 weeks. Conditions of vascular injuries were evaluated with general observation of clamping arteries, vascular ultrasound for blood flow, histomorphology observation and vascular traumatic scores. Results The clamping arteries of rats in the two groups recovered well with smooth blood flow, and there was no neointimal formation in the inner layer by HE ( hematoxylin and eosin) staining, and there were no statistically significant differences in vascular traumatic scores between left and right common carotid arteries (P>0. 05). Conclusion Vascular injuries by vascular clamps during the process of vascular anastomosis are inevitable, but the impermanent injures can be repaired by itself.

  20. Effects of Environmental Medium and Surface Structure on the Friction Performance of CT Clamping Block%环境介质及表面结构对夹持块摩擦性能的影响

    Institute of Scientific and Technical Information of China (English)

    任武; 袁文才; 谭文锋; 徐云喜; 刘鑫; 李世龙

    2012-01-01

    连续管注入头夹持块在使用过程中表面会粘附钻井液、原油和石蜡等井下介质,从而对夹持块摩擦性能造成影响,另外夹持块表面结构形式的不同也会对摩擦性能造成影响。为此,用自行设计的测试设备对夹持块与连续管在不同条件下的当量摩擦因数进行测试及分析。分析结果表明,对于光面夹持块,在无介质条件下,其当量摩擦因数为0.443;原油对当量摩擦因数影响较小,石蜡对夹持块摩擦性能影响最大,其当量摩擦因数下降至0.074;对于无介质环境下的表面刻槽夹持块,齿宽和槽宽越窄,夹持性能越好;在石蜡环境下,23型夹持块有效减少了接触面上的石蜡,摩擦性能大幅度提高。%There are adhesion downhole media on the CT clamping block, such as slurry, crude oil and paraffin in its application process. As a result, the friction performance of the block will be affected. Moreover, the difference in the surface structure of the block will also have effect on its friction performance. Therefore, the self-designed testing apparatus was used to test and analyze the equivalent friction coefficient of the block and CT in different conditions. The findings show that as for smooth surface clamping block, the equivalent coefficient is 0. 443 when there is no medium. Crude oil has slight effect on the coefficient. Paraffin has the maximum effect on the friction performance of the block and the coefficient decreases to 0. 074. As for the medium - free clamping block with surface notch groove, the narrower the tooth width and groove width, the higher the clamping performance. In the environment of paraffin Model 23 clamping block effectively reduces the paraffin on the contact surface and the friction performance increases remarkably.

  1. 蚊式钳夹法联合自制水媒电刀切除巨大肝癌的研究%Mini-clamp crushing combined with saline-linked diathermy in hepatectomy for giant hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    夏锋; 别平; 马宽生; 李晓武; 王曙光

    2010-01-01

    目的 探讨蚊式钳夹法联合自制水媒电刀行巨大肝癌肝切除的手术疗效.方法 回顾性分析2006年4月至2009年12月第三军医大学西南医院应用蚊式钳夹法对58例巨大肝癌(直径≥10 cm)患者(蚊式钳夹组)行肝切除术的临床资料.同时根据肿瘤直径、部位和肝功能Child分级在肝癌数据库中配对选取58例采用传统钳夹法进行手术的患者(传统钳夹组)的临床资料.对两组患者术中和术后的相关指标采用方差分析、X2检验和Fisher确切概率法进行分析.结果 传统钳夹组的中位出血量和输血量分别为850 ml和650 ml,明显多于蚊式钳夹组的400 ml和550 ml(F=16.23,5.63,P<0.05);传统钳夹组输血患者为24例,多于蚊式钳夹组的6例(χ~2=14.57,P<0.05);传统钳夹组的中位肝实质离断时间和肝门阻断时间分别为45 min和16 min,少于蚊式钳夹组的86 min和35 min(F=12.76,11.23,P<0.05);传统钳夹组患者43例出现并发症,其中28例发生出血,明显高于蚊式钳夹组的13例和8例(χ~2=18.69,16.11,P<0.05).传统钳夹组患者发生胆汁漏、肝断面包裹性积液和肝功能不全分别为8例、5例、2例,多于蚊式钳夹组的2例、3例和0例,但两组比较差异无统计学意义(χ~2=3.04,0.54,2.04,P>0.05).结论 应用蚊式钳夹法联合自制水媒电刀行肝切除效果满意,所需器械简单,优于传统钳夹法,是一种较简便而实用的肝切除方法.%Objective To evaluate the efficacy of mini-clamp crushing combined with saline-linked diathermy in hepatectomy for giant hepatocellular carcinoma(HCC).Methods The clinical data of 58 patients with giant HCC(diameter≥10 cm)who received hepatectomy with the mini-clamp crushing technique(miniclamp crushing group)at the Southwest Hospital from April 2006 to December 2009 were retrospectively analysed.According to the tumor size,location and Child classification,the clinical data of 58 patients with similar parameters and

  2. Anti-slip Performance of Interface between Carbon Fiber-Reinforced Plastic Main Cable and Cable Clamp for Large-Span Suspension Bridges%大跨悬索桥CFRP主缆-索夹界面抗滑移性能

    Institute of Scientific and Technical Information of China (English)

    诸葛萍; 章子华; 汪思聪; 丁勇; 强士中

    2014-01-01

    In order to solve the slip problem between main cable and clamp at saddles of large-span suspension bridges,the anti-slip performance of the interface between carbon fiber reinforced plastic (CFRP)cable and cable clamp was investigated. The frictional coefficient calculation formula of the interface was derived according to the equilibrium condition between the cable tension and the friction force on the interface. Based on this formula,the friction coefficient of the cable-clamp interface was obtained through laboratory model test using a cable composed of 19 CFRP tendons. Then,the test results of frictional coefficient were used to analyze the anti-slip performance of the main cable-clamp system of a CFRP cable suspension bridge with a main span of 3 500 m,where the CFRP tendons had a spirally indented surface. The results show that the friction coefficient of the CFRP main cable-cable clamp interface is up to 0. 331,which is higher than that of steel cable,and meet the requirement of engineering application. Therefore,when the CFRP tendons with a spirally indented surface are applied to the main cables of large-span suspension bridges,the cable-clamp interface is good enough to meet the requirement in anti-slip performance even if the cable clamps are designed in conventional shape and with an inner surface not granulated specially.%为解决大跨悬索桥碳纤维增强复合材料(CFRP)主缆鞍座处的抗滑移问题,研究了CFRP主缆-索夹界面的抗滑移性能,根据力的平衡原理推导了CFRP索股-索夹界面的摩擦因数计算式,结合模型试验和计算式,测试了19丝CFRP索股-索夹界面的摩擦因数.利用摩擦因数实测值对3500 m跨悬索桥CFRP主缆索夹处抗滑移性能进行了实桥应用分析.结果表明:压纹类CFRP丝主缆-索夹界面的摩擦因数超过钢主缆-索夹界面,达到0.331,可满足相应的应用要求;大跨悬索桥主缆采用压纹类CFRP丝时,索夹内表

  3. Formation, Characterization, and O-O Bond Activation of a Peroxomanganese(III) Complex Supported by a Cross-Clamped Cyclam Ligand.

    Science.gov (United States)

    Colmer, Hannah E; Howcroft, Anthony W; Jackson, Timothy A

    2016-03-01

    Although there have been reports describing the nucleophilic reactivity of peroxomanganese(III) intermediates, as well as their conversion to high-valent oxo-bridged dimers, it remains a challenge to activate peroxomanganese(III) species for conversion to high-valent, mononuclear manganese complexes. Herein, we report the generation, characterization, and activation of a peroxomanganese(III) adduct supported by the cross-clamped, macrocyclic Me2EBC ligand (4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane). This ligand is known to support high-valent, mononuclear Mn(IV) species with well-defined spectroscopic properties, which provides an opportunity to identify mononuclear Mn(IV) products from O-O bond activation of the corresponding Mn(III)-peroxo adduct. The peroxomanganese(III) intermediate, [Mn(III)(O2)(Me2EBC)](+), was prepared at low-temperature by the addition of KO2 to [Mn(II)(Cl)2(Me2EBC)] in CH2Cl2, and this complex was characterized by electronic absorption, electron paramagnetic resonance (EPR), and Mn K-edge X-ray absorption (XAS) spectroscopies. The electronic structure of the [Mn(III)(O2)(Me2EBC)](+) intermediate was examined by density functional theory (DFT) and time-dependent (TD) DFT calculations. Detailed spectroscopic investigations of the decay products of [Mn(III)(O2)(Me2EBC)](+) revealed the presence of mononuclear Mn(III)-hydroxo species or a mixture of mononuclear Mn(IV) and Mn(III)-hydroxo species. The nature of the observed decay products depended on the amount of KO2 used to generate [Mn(III)(O2)(Me2EBC)](+). The Mn(III)-hydroxo product was characterized by Mn K-edge XAS, and shifts in the pre-edge transition energies and intensities relative to [Mn(III)(O2)(Me2EBC)](+) provide a marker for differences in covalency between peroxo and nonperoxo ligands. To the best of our knowledge, this work represents the first observation of a mononuclear Mn(IV) center upon decay of a nonporphyrinoid Mn(III)-peroxo center. PMID:26908013

  4. Improvement of Anti-fire Cap Clamp and Its Field Application Effect%防火帽卡箍的改进及现场应用效果

    Institute of Scientific and Technical Information of China (English)

    张洪岐; 姚婷; 李东波; 刘莲萍; 陶国庆

    2013-01-01

      防火帽又称火花熄灭器,是一种安装在机动车、内燃机排气管路后,允许排气流通过,且阻止排气流内的火星喷出的安全防火、阻火装置。在集输泵站油气密集场所一般使用的是MWLF-120长期配装型防火帽。进站前由车辆司机选择防火帽进行安装,安装时所选防火帽规格要与排气管口径吻合,然后用开口扳手拧紧卡箍两端螺丝固定在排气管尾部,否则车辆以及施工机械在运动的过程中很容易使防火帽失效和脱落,脱落后车辆将防火帽压坏,给集输泵站安全管理工作带来较大安全隐患。%  Anti-fire cap, also known as spark arrester, is a fire safety installation set after motor vehicle and engine exhaust pipe to allow the exhaust air flow through and prevent the mars ejected. The gathering and transportation station belonging to oil and gas crowded place is equipped with MWLF-120 long-retardant anti-fire cap in general. Before going to station, the vehicle driver chooses anti-fire cap whose specification should coincide with the exhaust pipe diameter, and then uses the open wrench to tighten the clamp screws in the tail of exhaust pipe, or the anti-fire cap is easy to be failure and loss in movement. If the anti-fire cap is falling off and crushed by the vehicle, it will bring greater security risks to the gathering and transportation station.

  5. Late cardiac sodium current can be assessed using automated patch-clamp [v1; ref status: indexed, http://f1000r.es/4kj

    Directory of Open Access Journals (Sweden)

    Morgan Chevalier

    2014-10-01

    Full Text Available The cardiac late Na+ current is generated by a small fraction of voltage-dependent Na+ channels that undergo a conformational change to a burst-gating mode, with repeated openings and closures during the action potential (AP plateau. Its magnitude can be augmented by inactivation-defective mutations, myocardial ischemia, or prolonged exposure to chemical compounds leading to drug-induced (di-long QT syndrome, and results in an increased susceptibility to cardiac arrhythmias. Using CytoPatch™ 2 automated patch-clamp equipment, we performed whole-cell recordings in HEK293 cells stably expressing human Nav1.5, and measured the late Na+ component as average current over the last 100 ms of 300 ms depolarizing pulses to -10 mV from a holding potential of -100 mV, with a repetition frequency of 0.33 Hz. Averaged values in different steady-state experimental conditions were further corrected by the subtraction of current average during the application of tetrodotoxin (TTX 30 μM. We show that ranolazine at 10 and 30 μM in 3 min applications reduced the late Na+ current to 75.0 ± 2.7% (mean ± SEM, n = 17 and 58.4 ± 3.5% (n = 18 of initial levels, respectively, while a 5 min application of veratridine 1 μM resulted in a reversible current increase to 269.1 ± 16.1% (n = 28 of initial values. Using fluctuation analysis, we observed that ranolazine 30 μM decreased mean open probability p from 0.6 to 0.38 without modifying the number of active channels n, while veratridine 1 μM increased n 2.5-fold without changing p. In human iPSC-derived cardiomyocytes, veratridine 1 μM reversibly increased APD90 2.12 ± 0.41-fold (mean ± SEM, n = 6. This effect is attributable to inactivation removal in Nav1.5 channels, since significant inhibitory effects on hERG current were detected at higher concentrations in hERG-expressing HEK293 cells, with a 28.9 ± 6.0% inhibition (mean ± SD, n = 10 with 50 μM veratridine.      

  6. 可夹持焊枪的氩弧焊自动焊接装置%Argon Arc Welding Automatic Welding Device with Clamping Welding Torch

    Institute of Scientific and Technical Information of China (English)

    张春红; 高开熠; 张宁; 常浩; 陈志伟

    2014-01-01

    针对人工焊接时由于焊接接头的熔深不同、焊缝宽度不同以及焊缝各处差异等人为因素所导致的焊接缺陷,设计了一种可夹持焊枪的氩弧焊自动焊接装置。介绍了可夹持焊枪的氩弧焊自动焊接装置的机械结构、控制模块及功能。该装置保证了稳定的焊接速度和焊接高度,实现了焊枪的三维移动和焊接过程的自动化,提高了焊接效率和焊接质量。利用此装置进行氩弧熔覆耐磨复合涂层的验证试验,试验结果表明该装置可实现组织均匀且与基底实现冶金结合的复合涂层,熔覆层硬度是基体Q235钢的6.4倍,耐磨性和表面质量良好。%During manual welding, aiming at the different fusion of welded joint, weld seam width and weld difference etc. factors which can cause welding defects, a kind of argon arc automatic welding device with clamping welding torch was designed. In this article, it introduced mechanical structure, control module and function of this device. This device can ensure stable welding speed and welding height, realize three-dimension movement of welding torch and welding process automation, and can increase welding efficiency and welding quality. Using this device to conduct verification test for argon arc cladding wear-resistant composite coating, the test results showed that the device can realize uniform organization and base metallurgical bonding confound coating, the coating layer hardness is 6.4 times that of the substrate Q235 steel, wear resistance and surface quality are good.

  7. LigaSure血管闭合系统结合钳夹法在肝叶切除术中的应用%The clinical application of LigaSure vessel sealing system combined with crushing clamp method in hepatolobectomy

    Institute of Scientific and Technical Information of China (English)

    徐永建; 佘明杰; 卢正磊

    2014-01-01

    目的:探讨LigaSure血管闭合系统结合钳夹法在肝叶切除术中的应用价值。方法:采用LigaSure血管闭合系统结合钳夹法闭合处理肝脏动静脉及门静脉三级以下分支,5-0 Proline线加LigaSure血管闭合系统闭合处理肝左静脉及肝中静脉属支。结果:手术时间127~230 min,术中失血150~500 ml,住院时间8~14 d,无术后腹腔内出血、胆漏及死亡病例。结论:LigaSure血管闭合系统结合钳夹法是一种安全可靠的肝叶切除方法。%Objective:To investigate the clinical application of LigaSure vessel sealing system( LVSS) combined with crushing clamp method in hepatolobectomy. Methods:The hepatic artery and vein and less than level 3 branch of portal vein were treated with LVSS and crushing clamp method, the branches of left hepatic vein and middle hepatic vein were treated with 5-0 Proline line ligature combined with LVSS. Results:The time of operation was 127-230 min,the volume of bleeding was 150-500 ml,and the average time of hospitalization stay was 8 to 14 days. No intra-abdominal hemorrhage, bile leakage and death after operation were found. Conclusions:LVSS combined with crushing clamp method in hepatolobectomy was a safe and reliable means.

  8. 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.

  9. Postoperative blood loss reduction in computer-assisted surgery total knee replacement by low dose intra-articular tranexamic acid injection together with 2-hour clamp drain: a prospective triple-blinded randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Paphon Sa-ngasoongsong

    2011-10-01

    Full Text Available A high-dose local tranexamic acid has been introduced in total knee arthroplasty for bleeding control. We are not sure about the systemic absorption and side effects. The aim of this study was to evaluate the effect of low dosage of intra-articular tranexamic acid injection combined with 2-hour clamp drain in minimally bleeding computer-assisted surgery total knee replacement (CAS-TKR. A prospective randomized controlled trial was conducted in a total of 48 patients underwent CAS-TKR. The patients were randomly assigned to receive either of a mixed intra-articular solution of tranexamic acid 250 mg with physiologic saline (TXA group, or physiologic saline (control group and then followed by clamp drain for 2 hours. Postoperative blood loss was measured by three different methods as drainage volume, total hemoglobin loss and calculated total blood loss. Transfusion requirement and postoperative complications were recorded. All patients were screened for deep vein thrombosis and the functional outcomes were evaluated at 6 months after surgery. The mean postoperative drainage volume, total hemoglobin loss and calculated total blood loss in TXA group were 308.8 mL, 2.1 g/dL and 206.3 mL compared to 529.0 mL, 3.0 g/dL and 385.1 mL in the control group (P=0.0003, 0.0005 and <0.0001 respectively. Allogenic blood transfusion was needed for one patient (4.2% in TXA group and for eight patients (33.3% in the control group. Postoperative knee scores were not significantly different between groups. No deep vein thrombosis, infection or wound complication was detected in both groups. In this study, low dose intra-articular tranexamic acid injection combined with 2-hour clamping drain was effective for reducing postoperative blood loss and transfusion requirement in CAS-TKR without significant difference in postoperative complications or functional outcomes.

  10. Postoperative blood loss reduction in computer-assisted surgery total knee replacement by low dose intra-articular tranexamic acid injection together with 2-hour clamp drain: a prospective triple-blinded randomized controlled trial

    Science.gov (United States)

    Sa-ngasoongsong, Paphon; Channoom, Thanaphot; Kawinwonggowit, Viroj; Woratanarat, Patarawan; Chanplakorn, Pongsthorn; Wibulpolprasert, Bussanee; Wongsak, Siwadol; Udomsubpayakul, Umaporn; Wechmongkolgorn, Supaporn; Lekpittaya, Nantaporn

    2011-01-01

    A high-dose local tranexamic acid has been introduced in total knee arthroplasty for bleeding control. We are not sure about the systemic absorption and side effects. The aim of this study was to evaluate the effect of low dosage of intra-articular tranexamic acid injection combined with 2-hour clamp drain in minimally bleeding computer-assisted surgery total knee replacement (CAS-TKR). A prospective randomized controlled trial was conducted in a total of 48 patients underwent CAS-TKR. The patients were randomly assigned to receive either of a mixed intra-articular solution of tranexamic acid 250 mg with physiologic saline (TXA group), or physiologic saline (control group) and then followed by clamp drain for 2 hours. Postoperative blood loss was measured by three different methods as drainage volume, total hemoglobin loss and calculated total blood loss. Transfusion requirement and postoperative complications were recorded. All patients were screened for deep vein thrombosis and the functional outcomes were evaluated at 6 months after surgery. The mean postoperative drainage volume, total hemoglobin loss and calculated total blood loss in TXA group were 308.8 mL, 2.1 g/dL and 206.3 mL compared to 529.0 mL, 3.0 g/dL and 385.1 mL in the control group (P=0.0003, 0.0005 and <0.0001 respectively). Allogenic blood transfusion was needed for one patient (4.2%) in TXA group and for eight patients (33.3%) in the control group. Postoperative knee scores were not significantly different between groups. No deep vein thrombosis, infection or wound complication was detected in both groups. In this study, low dose intra-articular tranexamic acid injection combined with 2-hour clamping drain was effective for reducing postoperative blood loss and transfusion requirement in CAS-TKR without significant difference in postoperative complications or functional outcomes. PMID:22053253

  11. In vivo cardiac glucose metabolism in the high-fat fed mouse: Comparison of euglycemic–hyperinsulinemic clamp derived measures of glucose uptake with a dynamic metabolomic flux profiling approach

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, Greg M., E-mail: greg.kowalski@deakin.edu.au [Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria 3125 (Australia); De Souza, David P. [Metabolomics Australia, Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria 3010 (Australia); Risis, Steve [Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria 3004 (Australia); Burch, Micah L. [Brigham and Women' s Hospital, Department of Medicine, Boston, MA (United States); Hamley, Steven [Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria 3125 (Australia); Kloehn, Joachim [Metabolomics Australia, Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria 3010 (Australia); Selathurai, Ahrathy [Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria 3125 (Australia); Lee-Young, Robert S. [Cellular and Molecular Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria 3004 (Australia); Tull, Dedreia; O' Callaghan, Sean; McConville, Malcolm J. [Metabolomics Australia, Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria 3010 (Australia); Bruce, Clinton R. [Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria 3125 (Australia)

    2015-08-07

    Rationale: Cardiac metabolism is thought to be altered in insulin resistance and type 2 diabetes (T2D). Our understanding of the regulation of cardiac substrate metabolism and insulin sensitivity has largely been derived from ex vivo preparations which are not subject to the same metabolic regulation as in the intact heart in vivo. Studies are therefore required to examine in vivo cardiac glucose metabolism under physiologically relevant conditions. Objective: To determine the temporal pattern of the development of cardiac insulin resistance and to compare with dynamic approaches to interrogate cardiac glucose and intermediary metabolism in vivo. Methods and results: Studies were conducted to determine the evolution of cardiac insulin resistance in C57Bl/6 mice fed a high-fat diet (HFD) for between 1 and 16 weeks. Dynamic in vivo cardiac glucose metabolism was determined following oral administration of [U-{sup 13}C] glucose. Hearts were collected after 15 and 60 min and flux profiling was determined by measuring {sup 13}C mass isotopomers in glycolytic and tricarboxylic acid (TCA) cycle intermediates. Cardiac insulin resistance, determined by euglycemic–hyperinsulinemic clamp, was evident after 3 weeks of HFD. Despite the presence of insulin resistance, in vivo cardiac glucose metabolism following oral glucose administration was not compromised in HFD mice. This contrasts our recent findings in skeletal muscle, where TCA cycle activity was reduced in mice fed a HFD. Similar to our report in muscle, glucose derived pyruvate entry into the TCA cycle in the heart was almost exclusively via pyruvate dehydrogenase, with pyruvate carboxylase mediated anaplerosis being negligible after oral glucose administration. Conclusions: Under experimental conditions which closely mimic the postprandial state, the insulin resistant mouse heart retains the ability to stimulate glucose metabolism. - Highlights: • Insulin clamp was used to determine the evolution of cardiac

  12. In vivo cardiac glucose metabolism in the high-fat fed mouse: Comparison of euglycemic–hyperinsulinemic clamp derived measures of glucose uptake with a dynamic metabolomic flux profiling approach

    International Nuclear Information System (INIS)

    Rationale: Cardiac metabolism is thought to be altered in insulin resistance and type 2 diabetes (T2D). Our understanding of the regulation of cardiac substrate metabolism and insulin sensitivity has largely been derived from ex vivo preparations which are not subject to the same metabolic regulation as in the intact heart in vivo. Studies are therefore required to examine in vivo cardiac glucose metabolism under physiologically relevant conditions. Objective: To determine the temporal pattern of the development of cardiac insulin resistance and to compare with dynamic approaches to interrogate cardiac glucose and intermediary metabolism in vivo. Methods and results: Studies were conducted to determine the evolution of cardiac insulin resistance in C57Bl/6 mice fed a high-fat diet (HFD) for between 1 and 16 weeks. Dynamic in vivo cardiac glucose metabolism was determined following oral administration of [U-13C] glucose. Hearts were collected after 15 and 60 min and flux profiling was determined by measuring 13C mass isotopomers in glycolytic and tricarboxylic acid (TCA) cycle intermediates. Cardiac insulin resistance, determined by euglycemic–hyperinsulinemic clamp, was evident after 3 weeks of HFD. Despite the presence of insulin resistance, in vivo cardiac glucose metabolism following oral glucose administration was not compromised in HFD mice. This contrasts our recent findings in skeletal muscle, where TCA cycle activity was reduced in mice fed a HFD. Similar to our report in muscle, glucose derived pyruvate entry into the TCA cycle in the heart was almost exclusively via pyruvate dehydrogenase, with pyruvate carboxylase mediated anaplerosis being negligible after oral glucose administration. Conclusions: Under experimental conditions which closely mimic the postprandial state, the insulin resistant mouse heart retains the ability to stimulate glucose metabolism. - Highlights: • Insulin clamp was used to determine the evolution of cardiac insulin

  13. Postoperative blood loss reduction in computer-assisted surgery total knee replacement by low dose intra-articular tranexamic acid injection together with 2-hour clamp drain: a prospective triple-blinded randomized controlled trial

    OpenAIRE

    Paphon Sa-ngasoongsong; Thanaphot Channoom; Viroj Kawinwonggowit; Patarawan Woratanarat; Pongsthorn Chanplakorn; Bussanee Wibulpolprasert; Siwadol Wongsak; Umaporn Udomsubpayakul; Supaporn Wechmongkolgorn; Nantaporn Lekpittaya

    2011-01-01

    A high-dose local tranexamic acid has been introduced in total knee arthroplasty for bleeding control. We are not sure about the systemic absorption and side effects. The aim of this study was to evaluate the effect of low dosage of intra-articular tranexamic acid injection combined with 2-hour clamp drain in minimally bleeding computer-assisted surgery total knee replacement (CAS-TKR). A prospective randomized controlled trial was conducted in a total of 48 patients underwent CAS-TKR. The pa...

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

  15. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N. P. Paulsson

    2006-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to perform high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology has been hampered by the lack of acquisition technology necessary to record large volumes of high frequency, high signal-to-noise-ratio borehole seismic data. This project took aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array has removed the technical acquisition barrier for recording the data volumes necessary to do high resolution 3D VSP and 3D cross-well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that promise to take the gas industry to the next level in their quest for higher resolution images of deep and complex oil and gas reservoirs. Today only a fraction of the oil or gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of detailed compartmentalization of oil and gas reservoirs. In this project, we developed a 400 level 3C borehole seismic receiver array that allows for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. This new array has significantly increased the efficiency of recording large data volumes at sufficiently dense spatial sampling to resolve reservoir complexities. The receiver pods have been fabricated and tested to withstand high temperature (200 C/400 F) and high pressure (25,000 psi), so that they can operate in wells up to 7,620 meters (25,000 feet) deep. The receiver array is deployed on standard production or drill tubing. In combination with 3C surface seismic or 3C borehole seismic sources, the 400

  16. 多曲面复杂卡箍的弯制及模具的设计%Exploration of Multi-Curved Surface Clamp Bending and its Mould Design

    Institute of Scientific and Technical Information of China (English)

    张慧云

    2012-01-01

    介绍了多曲面复杂卡箍的特点,分析板料在塑性变形过程中尺寸偏移的情况,明确中性层材料在弯曲过程中尺寸基本不变,绘制弯曲卡箍的展开图及其计算出弯曲部分的展开尺寸是卡箍弯制的前提.卡箍的形状、大小及其精度是设计弯曲模具的依据,确定多曲面卡箍弯制造的先后顺序,设计卡箍弯制模具及确定凸、凹模具间隙,使压制出的零件符合图样要求.%This paper introduces the characteristics of the multi-surface clamp, analysies plastic deformation size of migration in metal sheet processing, It is clear that the size of the neutral layer materials in its bending process is approximately same. The prerequisite is that the bending clamp figure is drawn and its development size of the bending part is calculated. Its shape size and precision are the bases for desiging the bending die and its order design and the convex and concare clearance of the die are deferminde in order to make pressed parts meet the requirement.

  17. 阴道分娩的断脐方法对胆红素及血红蛋白的影响%The effect of umbilical cord clamping on serum bilirubin and hemoglobin during vaginal delivery

    Institute of Scientific and Technical Information of China (English)

    王忠轩; 黄惠娟; 刘凤萍

    2011-01-01

    [ Objective ] To improve hemoglobin level but not increase serum bilirubin when the method of umbilical cord clamping is used during vaginal delivery. [Methods] Full term babys (n =120) were randomly assigned to experimental group (n =68) and control group (n =54). The umbilical cords of both groups were clamped within 30 seconds after birth. But the experimental group was clamped near the placenta and put up the distal remaining the cord untorsion in order to make the residual blood completely flow into the infants, while the control group was clamped by conventional method. The total serum bilirubin, peak-time of bilirubin, hemoglobin, hematocrit of the two groups were compared. [ Results ] The difference of serum bilirubin between two groups was not significant (P > 0.05). Hemoglobin and hematocrit of infants when birth and at 3-days of experimental group were higher than that of control group. The difference between two groups was significant (P <0.01). Hemoglobin and hematocrit of infants of experimental group at 3-days were higher than that of birth. The difference was significant (P <0.01); Hemoglobin and hematocrit of infants of control group at 3-days were also higher than that of birth, the difference was significant (P <0.05). [ Conclusion ] The method of umbilical cord clamping near the placenta within 30 seconds after birth during vaginal dehvery can not increase the incidence of jaundice induced by hyperbilirubinemia, but can improve hemoglobin level and reduce the incidence of anemia in infants.%目的 探讨断脐方法 以提高新生儿血红蛋白值但不增加胆红素值的研究.方法 对正常足月阴道分娩的新生儿120例,随机分为研究组58例和对照组62例.两组新生儿均于娩出后30 s内断脐,研究组断脐部位靠近胎盘端,并将远端抬高保持脐带不扭转,以便脐带内残余血迅速完全流入新生儿体内,再结扎处理脐部;对照组常规断脐处理残端.对两组新生儿的胆

  18. 海洋废弃平台桩基拆除绳锯机夹紧力的阻抗控制策略研究%Research on Impedance Control Strategy for Clamping Force of Offshore Discarded Platform Plies Removal Wire Saw

    Institute of Scientific and Technical Information of China (English)

    王海波; 田驰; 张岚; 王喆

    2012-01-01

    Piles may be cut off by underwater wire saw in the course of a discarded platform removal. The proper size clamping force is precondition for wire saw security and stability work. The wire saw clamping force control strategy was analyzed. The dynamics equations were established that wire saw clamped pile. Position-based neural network impedance control was proposed to control the clamping force, and a neural network compensator was designed. Basing on the actual wire saw engineering prototype, a variety of force controls were simulated. The results show that position-based neural network impedance control method is suitable for wire saw clamping force control, which can be a good compensation for clamping valve dynamic model and the position uncertainty.%海洋废弃平台拆除过程中可以采用水下绳锯机切断桩基,适当大小的夹紧力是绳锯机安全稳定工作的前提条件.分析绳锯机夹紧力控制策略,建立绳锯机夹紧瓣夹紧桩基时的动力学方程,提出采用位置型神经网络阻抗控制方法来控制夹紧力,设计神经网络补偿器.根据绳锯机的实际工程样机,对多种情况下的力控制进行仿真研究,结果表明:位置型神经网络阻抗控制方法可以很好地补偿夹紧瓣动力学模型和位置的不确定性,适合于绳锯机夹紧力控制.

  19. 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.

  20. Free-floating left atrial ball thrombus after mitral valve replacement with patent coronary artery bypass grafts: successful removal by a right minithoracotomy approach without aortic cross-clamp.

    Science.gov (United States)

    Hisatomi, Kazuki; Hashizume, Koji; Tanigawa, Kazuyoshi; Miura, Takashi; Matsukuma, Seiji; Yokose, Shogo; Kitamura, Tessho; Shimada, Takashi; Eishi, Kiyoyuki

    2016-06-01

    A free-floating thrombus in the left atrium without attachment to either the atrial wall or the mitral valve is extremely rare. We describe a case in a 79-year-old woman with chronic atrial fibrillation and a recent stroke who had undergone mitral valve replacement 25 years previously and coronary artery bypass grafting 5 years previously. Redo cardiac surgery represents a clinical challenge due to a higher rate of peri-operative morbidity and mortality. Median re-sternotomy can be particularly difficult in patients with functioning coronary artery grafts, where the risk of graft injury is a significant concern. Prompt surgical intervention was carried out, and to avoid the challenge of re-sternotomy in this patient with two prior thoracotomies, we successfully removed the thrombus by a right minithoracotomy approach without aortic cross-clamping. There was no postoperative occurrence of a new stroke or aggravation of the pre-existing stroke. PMID:25098689

  1. Excellent performances of energy harvester using cantilever driving double-clamped 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 plates and symmetric middle-stops

    International Nuclear Information System (INIS)

    We present a high performance nonlinear piezoelectric energy harvester constituted by a cantilever with symmetrically middle-stops and double-clamped piezoelectric plates based on piezoelectric single crystal 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3. Electrical properties of the device under different excitation frequencies, accelerations, and load resistances are studied systematically. Under a low acceleration of 3 m/s2 (0.3 g), a peak voltage of 26.2 V and a maximum normalized power of 25.6 mW/g2 were obtained across a matching impedance of 600 kΩ with favorable bandwidths. The low excitation acceleration and excellent performances indicate that the device can be a promising candidate for energy harvesting in low-power electronics and wireless sensors

  2. Research and Application on Clamping Method of Marine Crankshaft during Finish Machining%船用曲轴精加工装夹方法研究与应用

    Institute of Scientific and Technical Information of China (English)

    曹守启; 赵洋; 朱雅雯; 付淑漫

    2014-01-01

    对于船用发动机,曲轴的质量直接影响其整体寿命。在大型半组合式船用曲轴的加工过程中,作为最终工序的整体精加工又是决定最终质量的关键。基于有限元技术,分析了传统装夹定位方法带来的定位刚性差的原因所在;同时结合曲轴自身特点,设计了一种新型定位与装夹方式,为大型、偏心、轴类零件精加工提供理论与方法支持。%For marine engine,the quality of the crankshaft is a decisive factor for its mechanical life. In the manufacturing processes of semi-built-up marine crankshaft,as the final process,finish machining of the entirety is vital for the crankshaft quality. Applying finite element method,the traditional way for clamping was analyzed and the problem of machining deformation because of poor rigid was pointed out. In addition,a new clamping method was put forward according to the structure characters of crankshaft, which provided technical support for theory research and practical manufacturing. Moreover,a further research direction to increase the machining quality was proposed.

  3. Research and Application on Clamping Method of Marine Crankshaft during Finish Machining%船用曲轴精加工装夹方法研究与应用

    Institute of Scientific and Technical Information of China (English)

    曹守启; 赵洋; 朱雅雯; 付淑漫

    2014-01-01

    For marine engine,the quality of the crankshaft is a decisive factor for its mechanical life. In the manufacturing processes of semi-built-up marine crankshaft,as the final process,finish machining of the entirety is vital for the crankshaft quality. Applying finite element method,the traditional way for clamping was analyzed and the problem of machining deformation because of poor rigid was pointed out. In addition,a new clamping method was put forward according to the structure characters of crankshaft, which provided technical support for theory research and practical manufacturing. Moreover,a further research direction to increase the machining quality was proposed.%对于船用发动机,曲轴的质量直接影响其整体寿命。在大型半组合式船用曲轴的加工过程中,作为最终工序的整体精加工又是决定最终质量的关键。基于有限元技术,分析了传统装夹定位方法带来的定位刚性差的原因所在;同时结合曲轴自身特点,设计了一种新型定位与装夹方式,为大型、偏心、轴类零件精加工提供理论与方法支持。

  4. Research on phase-shifted full-bridge converter with clamping auxiliary resonant branch in the first side of transformer%原边带箝位辅助谐振支路的移相全桥变换器

    Institute of Scientific and Technical Information of China (English)

    耿攀; 李洪义; 谢炜; 柳彬; 李小谦

    2013-01-01

    移相全桥零电压变换器是中大功率直流变换的理想拓扑结构,但在其输出整流二极管反向恢复时,整流桥产生寄生振荡,二极管上存在很高的尖峰电压.本文从工作过程、损耗和效率等方面分析比较了超前型原边带箝位二极管的辅助谐振支路和滞后型原边带箝位二极管的辅助谐振支路.仿真和实验表明,超前型带箝位二极管辅助谐振支路能够更有效地抑制输出整流二极管两端的电压振荡,提高效率,降低损耗.%The phase-shifted full-bridge zero-voltage-switching PWM converter is widely used at medium and high power levels. However, there exists a problem of this kind of converter, that the output rectifier diodes suffer the parasitic oscillation and voltage spike resulted by the reverse recovery of the rectifier diodes. The paper makes comparison between leading type and legging type auxiliary resonant branch with clamping diodes in the first side of transformer from the working process, losses and effciency ets. The simulations and tests results show that leading type auxiliary resonant branch with clamping diodes makse the voltage oscillation in the both ends of the output rectifier diodes more effectively restrained, improves the efficiency and reduces the losses of the circuit.

  5. 辛氏钳钳夹阻断肝静脉技术在复杂肝脏肿瘤切除术中的应用%Hepatic vein occlusion with Satinsky clamp in hepatectomy for complicated liver tumor

    Institute of Scientific and Technical Information of China (English)

    汪珍光; 周伟平; 吴孟超; 傅思源; 潘泽亚; 黄罡; 杨远; 章琎; 刘辉; 林川; 李爱军

    2012-01-01

    目的 探讨改良的肝静脉阻断技术在复杂肝脏肿瘤切除手术中的应用.方法 2003年1月至2010年12月,采用Pringle法加辛氏钳钳夹阻断肝静脉技术切除第二肝门区复杂肝脏肿瘤330例.其中男性245例,女性85例:平均年龄(50±11)岁.肿瘤平均直径(9土6)cm.271例患者合并乙肝,215例合并肝硬化;术前肝功能Child A级321例,B级9例.术中血流阻断方式采用Pringle法联合辛氏钳钳夹阻断肝静脉技术,使用钳夹法切肝.结果 330例患者术中均成功采用了辛氏钳钳夹阻断肝静脉技术.平均手术时间( 132±29) min,平均肝静脉分离时间(7±3) min,平均术中肝血流阻断时间(22±7)min.平均术中出血量(480±265) ml,66例患者输血,平均输血量1.2单位浓缩红细胞.术中未出现肝静脉大出血、空气栓塞和肝静脉分离失败.手术相关并发症61例(18.5%),包括31例胸腔积液、14例腹腔积液、10例胆漏、2例术中大出血、2例术后再出血、2例肝功能不全.围手术期无死亡病例.结论 辛氏钳钳夹阻断肝静脉技术操作简便,成功率高,适合临床推广应用.%Objective To investigate the application of an improved method of hepatic vein occlusion with Satinsky clamp when resecting the liver tumor involving second hepatic portal. Methods From January 2003 to December 2010,there were totally 330 patients with liver tumor admitted,who underwent liver resection with Pringle maneuver plus hepatic vein occlusion with Satiusky clamp. Data regarding the intra-operative and post-operative course of the patients were analyzed.There were 245 male and 85 female patients,with a mean age of ( 50 ± 11 ) years.The diameter of tumor was (9 ± 6) cm.Among the 330 patients,there were 271 patients with viral hepatitis B,215 patients with liver cirrhosis; 321patients were in Child class A of liver function and 9 in class B. Pringle maneuver plus hepatic vein occlusion with Satinsky clamp was used to occlude the

  6. Optimization of Clamping Force of Wire Saw for Offshore Discarded Platform Plies Removal Based on Particle Swarm%基于粒子群算法的海洋废弃平台桩基拆除绳锯机夹紧力优化

    Institute of Scientific and Technical Information of China (English)

    王海波; 张岚; 孟庆鑫; 王喆

    2013-01-01

      水下绳锯机可以用来完成海洋废弃平台桩基切割。绳锯机切割过程中,当水下环境发生变化时,应能够较迅速地调整夹紧力以适应环境的改变。介绍绳锯机的夹紧数学模型,根据绳锯机的实际设计条件,采用粒子群算法对夹紧力进行快速的优化求解。通过实验表明,此方法获得的夹紧力能够使绳锯机稳定地工作,并且测得了相应的动态参数。研究结果为绳锯机夹紧力的水下环境快速自适应控制提供了一定的基础。%Underwater wire saw can be used to cut offshore discarded platform plies. When the underwater environment changes in cutting process,it should adjust clamping force quickly to adapt to the changes. The wire saw clamp mathematical model was de-scribed. According to wire saw actual design conditions,clamping force was quickly solved using particle swarm algorithm. Experi-ments show that using obtained clamping force,wire saw can work stably. Corresponding dynamic parameters were measured. The re-sults provide a foundation for the wire saw clamping force quickly adaptive control in the underwater environment.

  7. 钳夹法与射频辅助肝癌切除术的对比研究%Comparative study of clamp-crushing versus radiofrequency-assisted liver resection for hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    马海; 田云鸿; 杨红春; 李永; 彭勇

    2015-01-01

    目的 对比钳夹法与射频辅助肝癌切除对患者预后的影响.方法 将我院2010年1月至2014年6月105例肝癌手术患者分为钳夹法组和射频辅助法组,对比两组患者的切肝时间、肝门阻断时间、术中出血量、切肝出血量、平均手术时间、术后住院时间、并发症发生率、术后无瘤生存率及总生存率.结果 射频辅助切肝组切肝时间、肝门阻断时间较短,术中出血量、切肝出血量较少.两组平均手术时间差异无统计学意义(P>0.05).两组术后无瘤生存率和总生存率差异无统计学意义.结论 射频辅助肝癌切除是一种可行的手术方式.%Objective To analyze the outcome of clamp-crush technique versus radiofrequency-assisted liver resection for hepatocellular carcinoma.Methods105 patients with hepatocellular carcinoma (HCC) who underwent liver resection were divided into Clamp-crush group (CC group) and radiofrequency-assisted group (RF group) from January 2010 to June 2014. The transaction and operation time, hepatic ischemic time, total blood loss, blood loss during transaction, operative time, postoperative hospital stay, complications, disease-free and overall survival rate between the two groups were compared.Results The RF group had less transaction time, hepatic ischemic time, total blood loss, blood loss during transaction compared to the CC group. The total operative time, disease free survival and overall survival were comparable between these two groups (P>0.05).Conclusion Radiofrequency- assisted liver resection is feasible for hepatocellular carcinoma.

  8. Characterization of Endogenous Sodium Channels in the ND7-23 Neuroblastoma Cell Line: Implications for Use as a Heterologous Ion Channel Expression System Suitable for Automated Patch Clamp Screening.

    Science.gov (United States)

    Rogers, Marc; Zidar, Nace; Kikelj, Danijel; Kirby, Robert W

    2016-03-01

    The rodent neuroblastoma cell line, ND7-23, is used to express voltage-dependent sodium (Nav) and other neuronal ion channels resistant to heterologous expression in Chinese hamster ovary (CHO) or human embryonic kidney (HEK) cells. Their advantage is that they provide endogenous factors and signaling pathways to promote ion channel peptide folding, expression, and function at the cell surface and are also amenable to automated patch clamping. However, ND7-23 cells exhibit endogenous tetrodotoxin (TTX)-sensitive Nav currents, and molecular profiling has revealed the presence of Nav1.2, Nav1.3, Nav1.6, and Nav1.7 transcripts, but no study has determined which subtypes contribute to functional channels at the cell surface. We profiled the repertoire of functional Nav channels endogenously expressed in ND7-23 cells using the QPatch automated patch clamp platform and selective toxins and small molecules. The potency and subtype selectivity of the ligands (Icagen compound 68 from patent US-20060025415-A1-20060202, 4,9 anhydro TTX, and Protoxin-II) were established in human Nav1.3, Nav1.6, and Nav1.7 channel cell lines before application of selective concentrations to ND7-23 cells. Our data confirm previous studies that >97% of macroscopic Nav current in ND7-23 cells is carried by TTX-sensitive channels (300 nM TTX) and that Nav1.7 is the predominant channel contributing to this response (65% of peak inward current), followed by Nav1.6 (∼20%) and negligible Nav1.3 currents (∼2%). In addition, our data are the first to assess the Nav1.6 potency (50% inhibitory concentration [IC50] of 33 nM) and selectivity (50-fold over Nav1.7) of 4,9 anhydro TTX in human Nav channels expressed in mammalian cells, confirming previous studies of rodent Nav channels expressed in oocytes and HEK cells. PMID:26991361

  9. An Equivalent Efficient Modeling Approach for Diode Clamp Sub-module Based MMC%一种二极管箝位型MMC的高效等值建模方法

    Institute of Scientific and Technical Information of China (English)

    周月宾; 饶宏; 许树楷; 罗雨; 黎小林

    2016-01-01

    Due to the ability of clearing dc faults by itself and low cost of power semiconductors, the modular multilevel converter based on diode clamp sub-modules (DCSM-MMC) is suitable for high voltage direct current transmission (HVDC) with long-distance overhead lines. For satisfying the need of project research, and fulfilling the electromagnetic transient simulations of DCSM-MMC with the same-size ratio, an equivalent efficient modeling method was proposed. According to the proposed approach, the cascaded sub-modules per arm of DCSM-MMC were equivalent to an arm voltage drop model and a composite equivalent model (CEM). The CEM is composed of four diodes, 2 switches and 2 controllable voltage sources. With the use of diode model supplied by the PSCAD/ EMTDC software, the CEM is capable of simulating the BLOCK and deBLOCK behaviors of DCSM-MMC accurately. Besides, the proposed method modeled the arm voltage drop more precisely, and simplified the modeling of controllable voltage sources. The research shows that the proposed approach is of accurate simulation results and higher efficient. Meanwhile, it can be used to the other sub-modules conveniently.%二极管箝位型模块化多电平换流器(modular multilevel converter based on diode clamp sub-module,DCSM-MMC)具有可自清除直流故障、电力电子器件成本低的优点,特别适合远距离架空线直流输电应用。为满足工程研究需求,实现 DCSM-MMC 的高效率“一比一”电磁暂态仿真,提出一种 DCSM-MMC 的高效等值建模方法。该方法将桥臂级联子模块等效为一个桥臂导通压降模型和一个复合等值模型。复合等值模型由4个辅助二极管、2个转换开关和2个受控电压源构成。通过借助PSCAD/EMTDC自身提供的二极管,复合等值模型有效解决了换流器闭锁、解锁行为的精确模拟问题。同时,所提方法对 DCSM-MMC 的桥臂导通压降进行了准确建模,简化了受控电压源的等值建

  10. Start control for the MMC-HVDC system based on clamp double submodule%基于箝位双子模块的MMC-HVDC起动控制策略

    Institute of Scientific and Technical Information of China (English)

    薛英林; 徐政

    2013-01-01

      分析了基于箝位双子模块的MMC-HVDC正常自励起动过程,将起动过程分为两个基本阶段,即不控充电阶段和可控充电阶段。利用电路原理方法化简了不控充电阶段的系统等值电路,推导了最大充电电流与限流电阻之间的关系,并指出在该阶段由于二极管箝位作用电容无法充电至额定状态。设计了三种可控充电方法以对电容继续充电获取足够的能量,其中方法一利用直流电压控制器和调制均衡策略,而方法二和方法三则通过改变充电回路中等效内电势和等效电容实现电容完全充电。为充分发挥系统故障穿越能力,设计了直流侧暂时性和永久性故障后的系统自动再起动控制时序。在PSCAD/EMTDC中搭建两端有源的MMC-HVDC系统,仿真结果表明所提出的起动控制策略效果良好。%The self-start procedure of the modular multilevel converter (MMC) based HVDC system which adopts clamp double submodules (CDSM) is analyzed. This procedure is divided into two basic stages, i.e., uncontrolled charging stage and controlled charging stage. The equivalent circuit in uncontrolled stage is simplified according to theorem of electrical circuit and the relationship between the maximum charging current and current-limit resistor is derived. Furthermore, it is indicated that all capacitors could not be fully charged to the rated value, owing to clamping functionality of diodes. In order to continuously charge these capacitors, three controlled charging methods are proposed, enabling that each achieves enough stored energy. Among them, method No. 1 takes advantage of the DC voltage controller, which uses the modulation and balancing strategy; method No. 2 and method No. 3 are realized by changing the charging loop’s equivalent electric potential and equivalent capacitance. In fully implementing the faults ride-through ability, auto-restart control sequences under temporary and

  11. Experimental study of acute spinal cord injury in rats with lipopolysaccharide infection after abdominal aorta clamping%腹主动脉阻断合并脓毒症大鼠脊髓损伤的实验研究

    Institute of Scientific and Technical Information of China (English)

    尹述洲; 吴安石

    2011-01-01

    目的 观察大鼠腹主动脉阻断术(AAC)后合并脓毒症时脊髓病理改变及肿瘤坏死因子(TNF)-α的表达.方法 Wistar大鼠32只,随机均分为四组:假手术组(A组),AAC组(B组),LPS组(C组),AAC+ LPS组(D组).所有动物均于再灌注后8h处死,处死前进行后肢神经功能评分,取脊髓行HE染色观察脊髓组织病理损害和免疫组化检测脊髓前角TNF-α的表达.结果 HE染色显示A组损伤较轻;B组可见炎性反应明显,较多神经元坏死;C组有炎性表现,较少神经元坏死,较多运动神经元凋亡;D组可见强烈炎性表现,大量神经元坏死.A组TNF-α少量表达,显著低于其它三组(P<0.01).C组TNF-α显著高于其它三组(P<0.01).A、C组后肢神经功能评分显著高于B、D组(P<0.05或P<0.01).结论 TNF-α在AAC后脓毒症急性脊髓损伤中发挥了重要作用,介导了运动神经元的坏死或凋亡.AAC后机体可存在免疫紊乱,如此时发生脓毒症,TNF-α表达增加可能不如单纯脓毒症明显.%Objective To study the pathological changes and the expression of TNF-α of rat spinal cord after abdominal aorta clamping ( ACC) with lipopolysaccharide ( LPS) infection. Methods Thirty-two Wistar rats were randomly divided into four groups (the dead were excluded): Sham(Group A,n=8),AAC (Group B, n=8),LPS (Group C, n=8),and AAC with LPS infection (Group D, n = 8). Eight hours after reperfusion. All the rats were excuted and eviscerate the spinal cord tissues. The pathological changes were observed after HE stain, and the expression of TNF-α were detected by immunohistochemistry methods. Results The pathological changes of 4 group-there was slight pathological change and no significant inflammatory reaction in group A. Group B showed slight inflammatory reaction and a small quantity of dynamoneure necrosis. The group C showed an obvious inflammatory reaction and more dynamoneure necrosis. The group D showed an obvious inflammatory reaction and a

  12. 快捷自锁增力夹紧机构钻模的分析与设计%Analysis and Design for Shortcut Self-Locking Force Increasing Clamping Mechanism Drilling Die

    Institute of Scientific and Technical Information of China (English)

    文根保; 史文; 文莉

    2011-01-01

    采用了板动手柄能使具有斜齿的齿轮轴带动着具有斜齿的齿条轴产生移动,移动可使设有导向装置并装有钻套的钻模板夹紧工件。由于夹紧力在斜齿上可分解成齿轮轴向分力的作用,使齿轮轴上制有的10°锥体与锥套的配合具有不可逆的自锁性能。这种自锁性能只能是手柄带动着齿轮轴的转动及齿条轴的移动,而不能是齿条轴带动着齿轮轴的转动。同时,手柄对齿轮和齿轮轴的锥体对锥套及工件都会产生增力的作用。%This is largely because the handle makes the gear axle with obliqur teeth drive gear shaft with obliqur to move, which makes drilling die plate with guide mechanism and drill sleeve to work elamply. As the clamping force on the helical gear can be decomposed into the role of axial pitch, which makes the the match between 10° cone on the gear shaft and sleeve shows an inreversible self-locking performance. This performance can only be handle driving a gear shaft to rotate and rack shaft to move, but not gear shaft drive gear shaft to rotate. Meanwhile, the handle and the cone of the gear shaft will have increased loads on gear, sleeve and workpiece.

  13. A new balancing three level three dimensional space vector modulation strategy for three level neutral point clamped four leg inverter based shunt active power filter controlling by nonlinear back stepping controllers.

    Science.gov (United States)

    Chebabhi, Ali; Fellah, Mohammed Karim; Kessal, Abdelhalim; Benkhoris, Mohamed F

    2016-07-01

    In this paper is proposed a new balancing three-level three dimensional space vector modulation (B3L-3DSVM) strategy which uses a redundant voltage vectors to realize precise control and high-performance for a three phase three-level four-leg neutral point clamped (NPC) inverter based Shunt Active Power Filter (SAPF) for eliminate the source currents harmonics, reduce the magnitude of neutral wire current (eliminate the zero-sequence current produced by single-phase nonlinear loads), and to compensate the reactive power in the three-phase four-wire electrical networks. This strategy is proposed in order to gate switching pulses generation, dc bus voltage capacitors balancing (conserve equal voltage of the two dc bus capacitors), and to switching frequency reduced and fixed of inverter switches in same times. A Nonlinear Back Stepping Controllers (NBSC) are used for regulated the dc bus voltage capacitors and the SAPF injected currents to robustness, stabilizing the system and to improve the response and to eliminate the overshoot and undershoot of traditional PI (Proportional-Integral). Conventional three-level three dimensional space vector modulation (C3L-3DSVM) and B3L-3DSVM are calculated and compared in terms of error between the two dc bus voltage capacitors, SAPF output voltages and THDv, THDi of source currents, magnitude of source neutral wire current, and the reactive power compensation under unbalanced single phase nonlinear loads. The success, robustness, and the effectiveness of the proposed control strategies are demonstrated through simulation using Sim Power Systems and S-Function of MATLAB/SIMULINK. PMID:27018144

  14. Stress Clamp Experiments on Multicellular Tumor Spheroids

    CERN Document Server

    Montel, Fabien; Elgeti, Jens; Malaquin, Laurent; Basan, Markus; Risler, Thomas; Cabane, Bernard; Vignjevic, Danijela; Prost, Jacques; Cappello, Giovanni; Joanny, Jean-François; 10.1103/PhysRevLett.107.188102

    2011-01-01

    The precise role of the microenvironment on tumor growth is poorly understood. Whereas the tumor is in constant competition with the surrounding tissue, little is known about the mechanics of this interaction. Using a novel experimental procedure, we study quantitatively the effect of an applied mechanical stress on the long-term growth of a spheroid cell aggregate. We observe that a stress of 10 kPa is sufficient to drastically reduce growth by inhibition of cell proliferation mainly in the core of the spheroid. We compare the results to a simple numerical model developed to describe the role of mechanics in cancer progression.

  15. Russia clamps downs on data release

    International Nuclear Information System (INIS)

    This paper reports that Russia is stepping up enforcement of laws banning unauthorized release of detailed geological and geophysical data to foreign companies. But companies authorized to sell or license information about Russian minerals say the stricter oversight isn't affecting their activities. That's because the effort is intended to curb illegal sales of data by Russian regional organizations and federal agencies. In addition, Russia's state tax department and ministries of finance and justice are considering sanctions to be imposed for violations of lawful procedures. The added vigilance by Russian officials likely will help clear up confusion among foreign companies, resulting from vague laws and regulations, about how and from whom data may be obtained obtained legally

  16. Efeitos do clampeamento tardio do cordão umbilical sobre os níveis de hemoglobina e ferritina em lactentes aos três meses de vida Effects of delayed cord clamping on hemoglobin and ferritin levels in infants at three months of age

    Directory of Open Access Journals (Sweden)

    Sonia Isoyama Venâncio

    2008-01-01

    Full Text Available Este estudo verificou o efeito do clampeamento tardio (um minuto após o nascimento do cordão umbilical sobre os níveis de hemoglobina e ferritina em crianças aos três meses de vida. Foram alocadas 325 mães e crianças, nascidas a termo, de parto vaginal e sem patologias (164 no grupo do clampeamento imediato e 161 no tardio em um hospital do Município de São Paulo, Brasil, em 2006. Realizaram-se dosagens de hemoglobina da mãe no pré-parto e de hemoglobina e ferritina do cordão umbilical. As crianças (69% foram acompanhadas no ambulatório, após três meses, ocorrendo coleta de sangue venoso para dosagem de hemoglobina e ferritina. Variáveis sócio-econômicas, reprodutivas, antropométricas e de alimentação da criança foram estudadas. Utilizou-se a regressão linear múltipla para a análise dos dados. O efeito do clampeamento tardio do cordão umbilical foi significativo somente para os níveis de ferritina das crianças aos três meses de idade (p = 0,040, sendo superior em 23,29ng/mL quando comparado às crianças submetidas ao clampeamento imediato. O procedimento pode se constituir em uma estratégia para prevenir a deficiência de ferro em lactentes.This study assessed the effect of delayed (1 minute after delivery clamping of the umbilical cord on hemoglobin and ferritin levels in infants at three months of age. Mothers and their infants born through vaginal delivery, at term, and without congenital anomalies (325 pairs were recruited at a hospital in São Paulo, Brazil, in 2006 (164 in the delayed clamping subgroup and 161 in the early clamping subgroup. Maternal hemoglobin at delivery, umbilical cord hemoglobin, and ferritin were recorded. At three months follow-up, venous blood samples were drawn from 224 (69% infants for hemoglobin and ferritin measurement. Socioeconomic, maternal reproductive, anthropometric, and infant feeding variables were studied. Multiple linear regression models were used to analyze the data

  17. Analysis on Fault Current Limitation and Self-recovery of MMC Based on Clamp Double Sub-module%基于钳位双子模块的 MMC 故障清除和重启能力分析

    Institute of Scientific and Technical Information of China (English)

    丁云芝; 苏建徽; 周建

    2014-01-01

    针对当前已投入运行的高压直流(HVDC)输电工程中模块化多电平换流器(MMC)不具备直流侧故障电流闭锁能力的问题,分析了一种可自清除直流侧故障电流并且可重启动的 MMC 拓扑---基于钳位双子模块的 MMC。这种拓扑可在发生直流故障时通过闭锁所有绝缘栅双极型晶体管(IGBT)的触发信号和利用二极管的反向阻断能力迅速完成闭锁过程,从而达到无需交流断路器动作实现清除直流故障的目的。这种拓扑将半桥模块化 MMC 的调制方法和控制策略与可清除直流故障能力结合在一起,且具有结构简单、造价经济等特点。通过对半桥模块化 MMC 和钳位双子模块 MMC 在直流侧双极短路故障情况下的故障电流进行分析和仿真,验证了基于钳位双子模块的 MMC 在处理直流侧故障方面的能力和效果。%In view of the inability of the modular multilevel converter (MMC) in the high voltage direct current (HVDC) transmission projects in current operation to lock fault current on the DC side,an MMC topology based on clamp double sub-module(CDSM)capable of automatically eliminating and restarting the fault current on the DC side is analyzed.Because of the reverse blocking of diodes,blocking during a DC fault is achieved by blocking all the impulses of IGBTs,then the DC fault is eliminated without the action of AC breakers.Simple in structure and economical,this topology combines the modulation and the control strategy of MMC based on half bridge sub-module(HBSM-MMC)with the ability of recovering from a DC fault.A comparison with the HBSM-MMC in the case of a DC pole-to-pole fault by simulation and analysis has proved the performance of MMC based on CDSM in the control of DC fault current.

  18. Isquemia hepática normotérmica em ratos: estudo da lesão celular através do uso de clampeamento pedicular contínuo e intermitente Normothermic hepatic ischemia in rats: study of celular injury by the use of continuous and intermittent pedicular clamping

    Directory of Open Access Journals (Sweden)

    Fabio Neves da Silva

    2002-12-01

    Full Text Available OBJETIVO: Avaliar as alterações bioquímicas decorrentes da isquemia hepática normotérmica, seguida de reperfusão em duas modalidades de clampeamento da tríade portal em ratos. MÉTODO: Trinta ratos Wistar machos pesando entre 250 e 320 gramas foram divididos em três grupos de 10 animais cada. Induzimos 40 minutos de isquemia hepática por clampeamento pedicular contínuo (grupo I ou intermitente (grupo II. No grupo controle não houve clampeamento. Como parâmetro de lesão hepatocelular adotamos a concentração plasmática de: transaminase glutâmico oxalacética (TGO, transaminase glutâmico pirúvica (TGP e lactato desidrogenase (LDH. Colhemos as amostras de sangue no início (T1 e no final da cirurgia (T2. Todos os animais foram submetidos ao mesmo tempo operatório: 60 minutos. RESULTADOS: Não houve diferença estatística nos valores iniciais (T1 das três enzimas nos três grupos. Todos apresentaram aumento significativo das enzimas do momento 1 (T1 para o momento 2 (T2. Houve diferença estatística no aumento médio de TGO e TGP entre os três grupos, sendo o maior aumento encontrado no grupo I e o menor, no grupo controle. Não houve diferença significativa, em relação à LDH, entre o grupo II e o grupo controle. No grupo I, entretanto, houve aumento significativo em relação aos demais. Conclusão: Comparado ao clampeamento contínuo, para um período total de 40 minutos de isquemia, o clampeamento da tríade portal em ratos realizado de forma intermitente, com ciclos de 10 minutos de isquemia e 5 minutos de reperfusão, provoca menor dano hepatocelular, o que foi constatado pela menor alteração enzimática.BACKGROUND: Our objective was to access the biochemical alterations due to hepatic warm ischemia followed by reperfusion in two modalities of portal triad clamping in rats. METHOD: We divided thirty male Wistar rats, weighting between 250 and 320 grams into three groups with 10 animals each. Forty minutes of hepatic

  19. Análise do comportamento do hemometabolismo cerebral durante endarterectomia carotídea com pinçamento transitório Análisis del comportamiento del hemometabolismo cerebral durante endarterectomia carotídea con pinzamiento transitorio Analysis of brain hemometabolism behavior during carotid endarterectomy with temporary clamping

    Directory of Open Access Journals (Sweden)

    Gastão Fernandes Duval Neto

    2004-04-01

    hipóxia oliguemica o desacoplamiento hemometabólico. El objetivo del presente estudio fue identificar las alteraciones del hemometabolismo cerebral, evaluados por medio de las alteraciones de la saturación de la oxihemoglobina en el bulbo de la vena yugular interna (SjO2, durante endarterectomia carotídea con pinzamiento, correlacionando esas alteraciones con factores con potencialidad de interferir con las mismas, principalmente la presión de CO2 expirada (P ET CO2 y la presión de perfusión cerebral (PPC. MÉTODO: Participaron del estudio 16 pacientes con enfermedad estenosante unilateral y sometidos al pinzamiento arterial transitorio durante endarterectomia carotídea. Los parámetros monitorizados (saturación de la oxihemoglobina en el bulbo de la vena yugular interna, stump pressure y la presión de CO2 expirado fueron analizados en los siguientes momentos: M1 - pre-pinzamiento; M2 - 3 minutos pos-pinzamiento; M3 - pre-despinzamiento; M4 - pos-despinzamiento. RESULTADOS: La comparación entre la SjO2 (%, Media ± DP en los períodos estudiados evidenció una diferencia entre la registrada en los momentos M1 (52,25 ± 7,87 y M2 (47,43 ± 9,19. Esa reducción inicial estabilizó durante el pinzamiento transitorio, con disminución en la comparación entre M2 y M3 (46,56 ± 9,25, sin significado estadístico (p = ns. En la fase pos despinzamiento, M4 (47,68 ± 9,12, la media de la SjO2 presentó una elevación, cuando comparada con los momentos de pinzamiento M2 e M3, más inferior al momento pre-pinzamiento M1 (M4 x M1 - p BACKGROUND AND OBJECTIVES: Carotid endarterectomy with temporary clamping changes cerebral blood flow and cerebral metabolic oxygen demand ratio with consequent oligemic hypoxia or hemometabolic uncoupling. This study aimed at identifying changes in brain hemometabolism, evaluated through changes in oxyhemoglobin saturation in internal jugular vein bulb (SvjO2 during carotid endarterectomy with clamping, and at correlating these changes

  20. Evaluation of the damage caused by clamping or section of cervical sympathetic nerve in rabbits Avaliação do dano causado pela clipagem ou secção do nervo simpático cervical em coelhos

    Directory of Open Access Journals (Sweden)

    Carlos Hespanha Marinho Junior

    2012-06-01

    Full Text Available PURPOSE: To study the macro and microscopic evaluation of the damage caused by clamping or section of cervical sympathetic nerve in rabbits, quantifying the collagen in the lesions. METHODS: Twenty rabbits were divided into two groups of ten, doing in group 1 (section section of the right cervical sympathetic nerve, while in group 2 (clipping clipping of the nerve. All rabbits were induced to death on the seventh day after surgery. The macroscopic variables were: consequences of nerve lesion, clip appearance, presence of infection and adhesions around the nerve. Microscopy used hematoxylin-eosin staining to evaluate the stages and the degree of inflammation and necrosis, and F3BA Picrosirius red staining to quantify collagen. Mann-Whitney test was used for comparisons of collagen types I and III between groups. Fisher exact test analyzed the macroscopic variables, the degree of inflammation and necrosis. RESULTS: There was no discontinuity of nerve injury in the clipping group, as well as the clip was closed in all animals. The presence of severe adhesions was significantly higher in the clipping group (pOBJETIVO: Estudar a lesão provocada pela secção e pela clipagem no nervo simpático cervical de coelhos, avaliando-se a macroscopia, microscopia e quantificando-se o colágeno nas lesões. MÉTODOS: Foram utilizados 20 coelhos, distribuídos em dois grupos de dez, sendo nos animais do grupo 1 (secção realizada secção do nervo simpático cervical direito, enquanto nos do grupo 2 (clipagem realizada a clipagem desse nervo. Todos os coelhos foram induzidos à morte no sétimo dia de pós-operatório. As variáveis macroscópicas avaliadas foram: presença de lesão de descontinuidade do nervo, aspecto do clipe, presença de infecção e de aderências ao redor do nervo. A microscopia com hematoxilina-eosina foi feita para avaliar as fases, o grau do processo inflamatório e a presença de necrose; a coloração de Picrosirius red F3BA

  1. 纤维喉镜下息肉前部钳夹法与支撑喉镜下摘除广基型声带息肉疗效分析%Curative effect analysis of the removal of wide base type of vocal cord polyps by self-retaining laryngoscope and polyp head clamps method under the fiber laryngoscope

    Institute of Scientific and Technical Information of China (English)

    孙宇鹏; 王晓光; 樊亚琴

    2013-01-01

    Objective: Compare curative effect of the removal of wide base type of vocal cord polyps by polyp head clamps method under the fiber laryngoscope to curative effect of the removal of wide base type of vocal cord polyps by self-retaining laryngoscope.Methods: Through surface anesthesia via fibrolaryngoscope make used of laryngeal forceps clamps method to remove the wide base type of vocal cord polyps from the front of the polyps 30 cases, in the same period, to remove it the traditional self-retaining laryngoscope 25 cases, compared to them by operation time and postoperative 3th day curative effect. the data is statistical analysed with SPSS17.0 software package. Results: The two groups of patients have obvious difference (P<0.05) in the operation time and postoperative 3th day curative effect.Conclusion: By using the polyp head clamps method under the fiber laryngoscope to treat the wide base type of vocal cords polyp than the traditional self-retaining laryngoscope is more conducive to surgery and quicker for postoperative recovery.%目的:比较纤维喉镜下息肉头部钳夹法摘除广基型声带息肉与传统支撑喉镜下摘除广基型声带息肉的疗效。方法在表面麻醉下经纤维喉镜使用喉钳钳夹法从广基型声带息肉头部摘除声带息肉30例,与同期在全麻下经传统支撑喉镜下摘除声带息肉25例患者比较手术时间及术后第3天时疗效,所得数据采用SPSS17.0软件包进行统计学分析。结果两组患者在手术时间及术后第3天时疗效比较有明显差异(P<0.05)。结论在用纤维喉镜下用息肉头部钳夹法治疗广基型声带息肉比传统支撑喉镜下摘除,更利于手术及术后恢复。

  2. Excellent performances of energy harvester using cantilever driving double-clamped 0.7Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3} plates and symmetric middle-stops

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Zhou; Xu, Qing [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Ren, Bo; Lin, Di; Di, Wenning; Luo, Haosu, E-mail: hsluo@mail.sic.ac.cn; Wang, Dong [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2015-10-26

    We present a high performance nonlinear piezoelectric energy harvester constituted by a cantilever with symmetrically middle-stops and double-clamped piezoelectric plates based on piezoelectric single crystal 0.7Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3}. Electrical properties of the device under different excitation frequencies, accelerations, and load resistances are studied systematically. Under a low acceleration of 3 m/s{sup 2} (0.3 g), a peak voltage of 26.2 V and a maximum normalized power of 25.6 mW/g{sup 2} were obtained across a matching impedance of 600 kΩ with favorable bandwidths. The low excitation acceleration and excellent performances indicate that the device can be a promising candidate for energy harvesting in low-power electronics and wireless sensors.

  3. Is subdiaphragmatic aortic cross-clamping a suitable model for spinal cord ischemia/reperfusion injury study in rats? O pinçamento sub-diagragmático da aorta é um modelo adequado para o estudo da lesão medular de isquemia/reperfusão em ratos?

    Directory of Open Access Journals (Sweden)

    Sonia Elizabeth Lopez Carrillo

    2006-08-01

    Full Text Available PURPOSE: To evaluate the efficacy of subdiaphragmatic aortic cross-clamping in an experimental model of ischemia/reperfusion injury of the spinal cord in albino rats. METHODS: Thirty-six male Wistar rats were randomized in two groups (n=18: G-1 (Sham and G-2 (Ischemia/Reperfusion, I/R. G-2 rats were submitted to 30 min subdiafragmatic aortic cross-clamping. G-1 rats served as controls and were submitted to surgical trauma (laparotomy without ischemia. Samples (spinal cord and arterial blood were collected at the end of ischemic period and 10 (T-10 and 20 (T-20 min later in G-2 rats. Sham rats (G-1 samples were collected at the same time-points. Blood and tissue metabolites concentrations of pyruvate, lactate, glucose and medullary adenosine triphosphate (ATP were assayed. RESULTS: Blood and tissue concentrations of pyruvate and glucose as well as lactate and medullary ATP were not different when comparing G1 to G2. Lactacemia was significantly elevated in G-2 compared with G-1 rats during reperfusion (T-10. CONCLUSION: Subdiaphragmatic aortic cord cross-clamping is not a suitable rat model for spinal cord ischemia/reperfusion injury study as it does not ensure changes in in vivo tissue metabolites concentrations similar to those found in tissues subjected to ischemia/reperfusion.OBJETIVO: Avaliar a eficácia do pinçamento da aorta subdiafragmática no modelo experimental de isquemia/reperfusão da medula espinhal em ratos. MÉTODOS: Trinta e seis ratos Wistar, machos, foram aleatoriamente distribuídos em 2 grupos (n=18 e submetidos ao pinçamento subdiafragmático da aorta, durante 30 minutos (Grupo-2 -Isquemia/Reperfusão. Os ratos do Grupo-1 (G-1 - Sham foram utilizados como controles e submetidos a laparotomia sem pinçamento arterial. As amostras (medula e sangue arterial foram coletadas ao término do período de isquemia (T-0 e 10 (T-10 e 20 (T-20 minutos mais tarde e nos mesmos intervalos, no grupo G-1. As concentrações teciduais e

  4. Efeitos da clonidina nas respostas cardiovasculares ao pinçamento aórtico infra-renal: estudo experimental no cão Efectos de la clonidina en las respuestas cardiovasculares al pinzamiento aórtico infra-renal: estudio experimental en el can Effects of clonidine on cardiovascular responses to infrarenal aortic cross-clamping: experimental study in dogs

    Directory of Open Access Journals (Sweden)

    Renato Viccário Achôa

    2003-09-01

    atrio derecho y de la arteria pulmonar ocluida (G Clon > G Control. Durante el pinzamiento aórtico, hubo en los dos grupos, aumento significante de las presiones del atrio derecho y arteria pulmonar ocluida, de los índices sistólico y del trabajo sistólico del ventrículo izquierdo, y diminución del índice de resistencia vascular pulmonar. En el grupo control hubo aumento significante de las presiones arterial media y de la arteria pulmonar, y de los índices cardíaco y del trabajo sistólico del ventrículo derecho. En el grupo clonidina, hubo diminución significante de la frecuencia cardíaca. Después del despinzamiento aórtico, hubo en los dos grupos: diminución significante de la frecuencia cardíaca y presión arterial media, en cuanto los valores de las presiones del atrio derecho e índice sistólico continuaron elevados. En el grupo control, los valores del índice de trabajo sistólico del ventrículo derecho continuaron elevados en cuanto los valores del índice cardíaco retornaron a valores próximos a los del control. En el grupo clonidina, los valores de las presiones del atrio derecho y de la arteria pulmonar ocluida, y el índice sistólico, continuaron significantemente elevados. CONCLUSIONES: En el can, en las condiciones experimentales empleadas, la administración venosa continua de clonidina atenúa las respuestas cardiovasculares decorrentes del pinzamiento aórtico infra-renal.BACKGROUND AND OBJECTIVES: Infrarenal aortic cross-clamping is associated to cardiovascular effects. Clonidine, an alpha2-agonist, determines bradycardia and hypotension. This study aimed at analyzing the effects of clonidine on the cardiovascular function of dogs submitted to infrarenal aortic cross-clamping. METHODS: This randomized study involved 16 mixed breed dogs randomly distributed in two groups: G Control - no clonidine; and G Clon - clonidine (5 µg.kg-1 immediately before aortic cross-clamping, followed by 2 µg.min-1.m² until the end of the study. All

  5. The intestinal tract as the major source of interleukin 6 production during abdominal aortic clamping and hind limb ischaemia-reperfusion injury O trato intestinal como a principal fonte na producao de interleucina 6 durante clampeamento da aorta abdominal e lesão de isquemia/rererfusão de membros inferiores

    Directory of Open Access Journals (Sweden)

    Márcio Benedito Palma Pimenta

    2007-01-01

    Full Text Available PURPOSE: The aim of this study was to investigate whether the hind limbs or intestinal tract is the most important initiator of the inflammatory response secondary aortic clamping and hind limb ischemia/reperfusion injury. METHODS: Blood samples of Wistar rats obtained from posterior cava vein, portal vein, and heart cavity during either laparotomy (control group, n=8 or laparotomy + 2 h of aortic clamping and bilateral hind limb ischemia (ischemia group, n=8, or 2 h after ischemia and 2 h of reperfusion (ischemia-reperfusion group, n=8 were assayed for interleukin 6 (IL-6 and C-reactive protein (CRP. RESULTS: Serum IL-6 at the heart (223.6±197.9 [10-832] pg/mL was higher (pOBJETIVO: Investigar qual o principal mediador da resposta inflamatória na lesao de isquemia/reperfusão após clampeamento da aorta abdominal e isquemia dos membros inferiores: o intestine ou as extremidades inferiores. MÉTODOS: amostra de sangue de ratos Wistar coletados da cava posterior, porta e cavidade cardíaca during tanto laparotomia (grupo controle n=8 ou laparotomia + 2 horas de clampeamento aórtico e isquemia bilateral de membros posteriores (grupo isquemia n=8, ou 2 h de isquemia seguido por 2 horas de reperfusão (grupo isquemia/reperfusão n=8, onde foram dosados interleucina 6 e proteína C-reativa. RESULTADOS: Il-6 no coração (223.6±197.9 [10-832] pg/mL foi maior (p<0.001 tanto na veia porta (133.08±108.52 [4-372] pg/mL quanto na veia cava posterior (127.58±109.15 [8-388] pg/mL. PCR não foi significativamente diferente entre os grupos. CONCLUSÃO: o trato intestinal foi responsável pela resposta inflamatória secundária a lesão de isquemia/reperfusão.

  6. DSA引导下经皮穿刺髓核钳夹联合臭气消融治疗颈椎间盘突出症的临床研究%Clinical Study of DSA-guided Percutaneous Nucleus Pulposus Clamp Combined with Ozone Ablation in the ;Treatment of Cervical Intervertebral Disc Hemiation

    Institute of Scientific and Technical Information of China (English)

    吴越宏; 符彦基; 庞亮明; 郭绍彬; 钟海英; 黄煜华

    2015-01-01

    目的:研究DSA引导下经皮穿刺髓核钳夹联合臭氧消融治疗颈椎间盘突出症的临床意义。方法:选择颈C4/5、C5/6、C6/7、C7/T1椎间盘突出症患者86例作为研究对象,钳夹组(A组)43例C6/7或C7/T1椎间盘突出患者采用DSA引导下经皮穿刺髓核钳夹联合臭氧消融治疗,射频组(B组)43例C4/5或C5/6椎间盘突出患者采用髓核射频热凝消融联合臭气消融术。观察比较两组各个时期的疼痛视觉模拟评分(visual analogue scale,VAS)以及临床疗效。记录手术过程中及术后的并发症。结果:两组术后24 h、72 h、1周,4周、12周VAS评分均低于术前,A组术后4周及12周的VAS评分低于B组,比较差异均有统计学意义(P<0.05)。术后12周,A组优良率为91.3%,B组为80.5%,A组失败率为8.7%,B组为19.5%。两组均无严重并发症发生。结论:DSA引导下经皮穿刺髓核钳夹联合臭气消融术是目前治疗颈椎间盘突出症最安全、有效的治疗方法。%Objective:To study the clinical significance of DSA-guided percutaneous nucleus pulposus clamp combined with ozone ablation in the treatment of cervical disc hermiation.Method:86 patients with cervical intervertebral disc hermiation of C4/5,C5/6,C6/7 or C7/T1 were selected as the research objects.43 patients with cervical intervertebral disc hermiation of C6/7 or C7/T1 in the clamp group(group A)were treated with DSA-guided percutaneous nucleus pulposus clamp combined with ozone ablation.43 patients with cervical intervertebral disc hermiation of C4/5 or C5/6 in the radio frequency group(group B)were treated with radiofrequency thermocoagulation combined with ozone ablation.The VAS scores and clinical effects in different stages of the two groups were observed and compared.Complications during and after the operation were recorded.Result:24 hours,72 hours,1 week,4 weeks and 12 weeks after the operation,the VAS scores of the two groups

  7. 脊髓切片中运动神经元的膜片箝技术研究:一种分析药物作用的高效工具%Patch clamp studies of motor neurons in spinal cord slices: a toolfor high-resolution analysis of drug actions

    Institute of Scientific and Technical Information of China (English)

    WANG Meng-Ya; Joan J KENDIG

    2000-01-01

    AIM: To develop a tool for detailed analysis of spinally acting anesthetic and analgesic agents. METHODS:Studies were done on visually identified motor neurons in 400 μm thick spinal cord slices from 14- 23 d old rats using patch clamp techniques. Ethanol was used as a prototype general anesthetic agent. RESULTS: Cell bodies in the ventrolateral horn identified as motor neurons by retrograde fluorescent labeling had a mean dimension of 32 ±5μm (x±s, n = 25). Mean resting potential was - 62.8 ± 2.4 mV; input resistance was 44±24MΩ (n=19). Threshold was -44±7 mV,and action potential amplitude 101 ± 9 mV from baseline.Ethanol concentrations at and below 50-200 mmol/L decreased motor neuron excitability to the injected current; there was no effect on resting potential, but a variable reversible increase in input resistance. Ethanol reversibly depressed the excitatory postsynaptic potential,with a dose-response relationship similar to that previously observed for the population excitatory postsynaptic potential in intact spinal cord in vitro. Ethanol also reversibly depressed currents evoked by glutamate, reducing total charge transfer to 40%±26% of control (x±s; n= 4). CONCLUSION: Reduction of connectivity in this relatively thick slice preparation does not significantly modify drag actions. The actions of ethanol on excitatory synaptic transmission observed in intact spinal cord are

  8. Clamping Effect on the Welding Residual Stresses of Monel Plates

    Czech Academy of Sciences Publication Activity Database

    Javadi, Y.; Hloch, Sergej

    Prešov: Technická univerzita v Košicích se sídlem v Prešově, 2013 - (Lehocká, D.; Cárach, J.; Knapčíková, L.; Hloch, S.), s. 362-366. (TEAM). ISSN 1847-9065. [International Scientific and Expert Conference of the International TEAM Society (Technique, Education, Agriculture & Management) /5./. Prešov (SK), 04.11.2013-06.11.2013] Institutional support: RVO:68145535 Keywords : monel * nickel alloy welding * finite element welding simulation * ultrasonic stress measurement * welding residual stress Subject RIV: JQ - Machines ; Tools

  9. 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...

  10. Single base pair mutation analysis by PNA directed PCR clamping

    DEFF Research Database (Denmark)

    Ørum, H.; Nielsen, P.E.; Egholm, M.; Berg, R.H.; Buchardt, O.; Stanley, C.

    1993-01-01

    A novel method that allows direct analysis of single base mutation by the polymerase chain reaction (PCR) is described. The method utilizes the finding that PNAs (peptide nucleic acids) recognize and bind to their complementary nucleic acid sequences with higher thermal stability and specificity...... than the corresponding deoxyribooligonucleotides and that they cannot function as primers for DNA polymerases. We show that a PNA/DNA complex can effectively block the formation of a PCR product when the PNA is targeted against one of the PCR primer sites. Furthermore, we demonstrate that this blockage...... allows selective amplification/suppression of target sequences that differ by only one base pair. Finally we show that PNAs can be designed in such a way that blockage can be accomplished when the PNA target sequence is located between the PCR primers....

  11. Real burst traffic amplification in optically gain clamped amplifier

    OpenAIRE

    Ennser, Karin; Taccheo, Stefano; Careglio, Davide; Solé Pareta, Josep; Aracil Rico, Javier

    2008-01-01

    Optical burst amplification in a gain-stabilized amplifier is theoretically investigated using real burst traffic data. The results show that excellent performance are obtained for WDM transmission with negligible interplay due to burst arrival statistics.

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

    Directory of Open Access Journals (Sweden)

    Vladimir Ruscin

    2008-01-01

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

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    An indirect matrix converter is an alternative "all-semiconductor" energy processor proposed recently for converting an ac source with fixed magnitude and frequency to a variable voltage and frequency supply that can meet the requirements of a particular industry application. In principle, an...... indirect matrix converter is constructed by connecting a front-end bidirectional rectification stage to a conventional two-level inversion stage with no bulky capacitive or inductive energy storage connected to their intermediate dc link. Through the proper modulation and compensation of the resulting...... converter, sinusoidal input current and output voltage can be achieved with minimized rectification switching loss, rendering the indirect matrix converter as a competitive choice for interfacing the utility grid to, e.g., defense facilities that require a different frequency supply. As an improvement, an...

  14. Bactridine's effects on DUM cricket neurons under voltage clamp conditions.

    Science.gov (United States)

    Forsyth, P; Sevcik, C; Martínez, R; Castillo, C; D'Suze, G

    2012-12-01

    We describe the effects of six bactridines (150 nM) on cricket dorsal unpaired median (DUM) neurons. The addition of bactridine 2 to DUM neurons induced a large current component with a reversal potential more negative than -30 mV, most evident at the end of the pulses. This current was completely suppressed when 1 μM amiloride was applied before adding the bactridines. Since the amiloride sensitive current is able to distort the aim of our study, i.e. the effect of bactridines on sodium channels, all experiments were done in the presence of 1 μM amiloride. Most bactridines induced voltage shifts of V(1/2) of the Boltzmann inactivation voltage dependency curves in the hyperpolarizing direction. Bactridines 1, 4 and 6 reduced Na current peak by 65, 80 and 24% of the control, respectively. The sodium conductance blockage by bactridines was voltage independent at potentials >20 mV. Bactridines effect on cricket DUM neurons does not correspond to neither α- nor β-toxins. Most bactridines shifted the inactivation curves in the hyperpolarizing direction without any effects on the activation m(∞)-like curves. Also bactridines differ from other NaScpTx in that they increased an amiloride-sensitive conductance in DUM neurons. Our result suggest that the α/β classification of sodium scorpion toxins is not all encompassing. The present work shows that bactridines target more than one site: insect voltage dependent Na channels and an amiloride-sensitive ionic pathway which is under study. PMID:23085555

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    -shaped inductance-capacitance (LC) impedance networks that are connected between two isolated dc input power sources and its inverter circuitry for boosting its AC output voltage. Through the design of an appropriate pulsewidth-modulation (PWM) algorithm, the two impedance networks can be short......-circuited sequentially (without shooting through the inverter full DC link) for implementing the ldquonearest-three-vectorrdquo modulation principle with minimized harmonic distortion and device commutations per half carrier cycle while performing voltage boosting. With only a slight modification to the inverter PWM...

  16. Thoracoscopic sympathetic clamping in a patient with an azygos fissure.

    Science.gov (United States)

    Moon, Seok Whan; Yoon, Jeong Sub; Jo, Keon Hyeon; Wang, Young Pil; Park, Hyeon Jin

    2005-04-01

    We believe that an azygos fissure may predispose to bleeding during thoracoscopic surgery. An azygos fissure causes important morphologic changes in the superior mediastinum and thereby poses a risk of massive bleeding during thoracoscopic procedures. We report on a successful thoracoscopic procedure conducted in a patient with palmar hyperhidrosis and an azygos fissure and emphasize that the course of the thoracic sympathetic chain runs laterally along the base of the azygos fissure. PMID:15821627

  17. Surface tension measurement from the indentation of clamped thin films.

    Science.gov (United States)

    Xu, Xuejuan; Jagota, Anand; Paretkar, Dadhichi; Hui, Chung-Yuen

    2016-06-21

    We developed an indentation technique to measure the surface tension of relatively stiff solids. In the proposed method, a suspended thin solid film is indented by a rigid sphere and its deflection is measured by optical interferometry. The film deflection is jointly resisted by surface tension, elasticity and residual stress. Using a version of nonlinear von Karman plate theory that includes surface tension, we are able to separate the contribution of elasticity to the total tension in the film. Surface tension is determined by extrapolating the sum of surface tension and residual stress to zero film thickness. We measured the surface tension of polydimethylsiloxane (PDMS) using this technique and obtained a value of 19.5 ± 3.6 mN m(-1), consistent with the surface energy of PDMS reported in the literature. PMID:27189735

  18. Plasma concentrations of osteoprotegerin during normo- and hyperglycaemic clamping

    DEFF Research Database (Denmark)

    Knudsen, S T; Jeppesen, Peter; Poulsen, P L;

    2007-01-01

    of the present study was to examine the effect of acute hyperglycaemia on plasma levels of OPG in non-diabetic subjects. MATERIAL AND METHODS: Nine healthy, lean, male subjects were examined in a randomized, blinded, cross-over study design during hyperglycaemic (plasma glucose = 15 mmol/L, study H...

  19. THD ANALYSIS OF DIFFERENT LEVELS IN DIODE CLAMPED INVERTER

    OpenAIRE

    Milind S Marathe; Vaibhav D Patil

    2013-01-01

    A multilevel inverter with assumed equal dc sources, the multilevel fundamental switching scheme is used to control the needed power electronics switches. Also, a method is presented where switching angles are computed such that a desired fundamental sinusoidal voltage is produced while at the same time certain higher order harmonics are eliminated. In this paper PWM switching technique in three, four, five, six-level diodeclamped multilevel inverter (DCMLI) has been tested in Matlab/Simulink...

  20. Efeitos do halotano, isoflurano e sevoflurano nas respostas cardiovasculares ao pinçamento aórtico infra-renal: estudo experimental em cães Efectos del halotano, isoflurano y sevoflurano en las respuestas cardiovasculares al pinzamiento aórtico infra-renal: estudio experimental en perros Effects of halothane, isoflurane and sevoflurane on cardiovascular responses to infrarenal aortic cross-clamping: experimental study in dogs

    Directory of Open Access Journals (Sweden)

    Flora Margarida Barra Bisinotto

    2003-08-01

    OBJECTIVES: Infrarenal aortic cross-clamping is associated to cardiovascular effects. This study aimed at analyzing the effects of halothane, isoflurane and sevoflurane on cardiovascular function of dogs following infrarenal aortic cross-clamping. METHODS: Thirty mongrel dogs were randomly divided in three groups, according to equipotent (0.75 MAC inhaled anesthetic doses: GH (n = 10 - 0.67% halothane; GI (n = 10 - 0.96% isoflurane; and GS (n = 10 - 1.8% sevoflurane. All dogs were submitted to infrarenal aortic cross-clamping for 30 minutes. Hemodynamic parameters were measured at control (C, at 15 (Ao15 and 30 (Ao30 minutes of aortic cross-clamping, and immediately (DAo and 15 (DAo15 minutes after aortic unclamping. RESULTS: In all groups, infrarenal aortic cross-clamping significantly increased mean blood pressure, right atrial pressure, cardiac index, stroke volume index, left ventricular work index and right ventricular work index. Pulmonary artery pressure significantly increased during cross-clamping in GI and GS groups while pulmonary capillary wedge pressure significantly increased in GH and GI groups. After aortic unclamping all hemodynamic parameters have returned to control levels with the exception of cardiac and stroke volume indices which remained high, followed by systemic vascular resistance index decrease. There have been no significant differences among groups in studied attributes, except for heart rate which was always lower in GH group as compared to other groups during and after infrarenal aortic cross-clamping. CONCLUSIONS: In dogs under our experimental conditions, equipotent concentrations (0.75 MAC of inhalational halothane, isoflurane and sevoflurane have not attenuated cardiovascular responses to infrarenal aortic cross-clamping.

  1. Tuning of dielectric, pyroelectric and ferroelectric properties of 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 ceramic by internal clamping

    Science.gov (United States)

    Patel, Satyanarayan; Chauhan, Aditya; Kundu, Swarup; Madhar, Niyaz Ahamad; Ilahi, Bouraoui; Vaish, Rahul; Varma, K. B. R.

    2015-08-01

    This study systematically investigates the phenomenon of internal clamping in ferroelectric materials through the formation of glass-ceramic composites. Lead-free 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 (BNT-BT-ST) bulk ferroelectric ceramic was selected for the course of investigation. 3BaO - 3TiO2 - B2O3 (BTBO) glass was then incorporated systematically to create sintered samples containing 0%, 2%, 4% and 6% glass (by weight). Upon glass induction features like remnant polarization, saturation polarization, hysteresis losses and coercive field could be varied as a function of glass content. Such effects were observed to benefit derived applications like enhanced energy storage density ˜174 kJ/m3 to ˜203 kJ/m3 and pyroelectric coefficient 5.7x10-4 Cm-2K-1 to 6.8x10-4 Cm-2K-1 by incorporation of 4% glass. Additionally, BNT-BT-ST depolarization temperature decreased from 457K to 431K by addition of 4% glass content. Glass incorporation could systematically increases diffuse phase transition and relaxor behavior temperature range from 70 K to 81K and 20K to 34 K, respectively when 6% and 4% glass content is added which indicates addition of glass provides better temperature stability. The most promising feature was observed to be that of dielectric response tuning. It can be also used to control (to an extent) the dielectric behavior of the host ceramic. Dielectric permittivity and losses decreased from 1278 to 705 and 0.109 to 0.107 for 6% glass, at room temperature. However this reduction in dielectric constant and loss increases pyroelectric figures of merit (FOMs) for high voltage responsivity (Fv) high detectivity (Fd) and energy harvesting (Fe) from 0.018 to 0.037 m2C-1, 5.89 to 8.85 μPa-1/2 and 28.71 to 61.55 Jm-3K-2, respectively for 4% added ceramic-glass at room temperature. Such findings can have huge implications in the field of tailoring ferroelectric response for application specific requirements.

  2. Tuning of dielectric, pyroelectric and ferroelectric properties of 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 ceramic by internal clamping

    Directory of Open Access Journals (Sweden)

    Satyanarayan Patel

    2015-08-01

    Full Text Available This study systematically investigates the phenomenon of internal clamping in ferroelectric materials through the formation of glass-ceramic composites. Lead-free 0.715Bi0.5Na0.5TiO3−0.065BaTiO3−0.22SrTiO3 (BNT-BT-ST bulk ferroelectric ceramic was selected for the course of investigation. 3BaO − 3TiO2 − B2O3 (BTBO glass was then incorporated systematically to create sintered samples containing 0%, 2%, 4% and 6% glass (by weight. Upon glass induction features like remnant polarization, saturation polarization, hysteresis losses and coercive field could be varied as a function of glass content. Such effects were observed to benefit derived applications like enhanced energy storage density ∼174 kJ/m3 to ∼203 kJ/m3 and pyroelectric coefficient 5.7x10−4 Cm−2K−1 to 6.8x10−4 Cm−2K−1 by incorporation of 4% glass. Additionally, BNT-BT-ST depolarization temperature decreased from 457K to 431K by addition of 4% glass content. Glass incorporation could systematically increases diffuse phase transition and relaxor behavior temperature range from 70 K to 81K and 20K to 34 K, respectively when 6% and 4% glass content is added which indicates addition of glass provides better temperature stability. The most promising feature was observed to be that of dielectric response tuning. It can be also used to control (to an extent the dielectric behavior of the host ceramic. Dielectric permittivity and losses decreased from 1278 to 705 and 0.109 to 0.107 for 6% glass, at room temperature. However this reduction in dielectric constant and loss increases pyroelectric figures of merit (FOMs for high voltage responsivity (Fv high detectivity (Fd and energy harvesting (Fe from 0.018 to 0.037 m2C−1, 5.89 to 8.85 μPa−1/2 and 28.71 to 61.55 Jm−3K−2, respectively for 4% added ceramic-glass at room temperature. Such findings can have huge implications in the field of tailoring ferroelectric response for application specific requirements.

  3. Three-Phase Independent Quasi-PR Control Strategy for Neutral Point Clamped Tri-Level Grid-Connection Photovoltaic Inverter%中点箝位式三电平光伏并网逆变器的三单相Quasi-PR控制策略

    Institute of Scientific and Technical Information of China (English)

    孙玉坤; 孙海洋; 张亮

    2013-01-01

    In view of the fact that the defects of narrow bandwidth and weak ability against frequency deviation in traditional proportion resonant (PR) controller can be remedied by quasi-proportion resonant (Quasi-PR) controller, based on three-phase independent Quasi-PR controller a control strategy for neutral point clamped (NPC) tri-level photovoltaic (PV) grid-connection inverter is proposed. The Quasi-PR controller inherits the advantages of traditional PR controller, so the complex coordinate transformation, decoupling control and feed-forward compensation in vector control strategy can be avoided and the control algorithm is simplified. Meanwhile, when grid frequency deviation occurs, the astatic tracking to AC current can still be performed by Quasi-PR controller. Besides, to decrease the content of higher harmonic current caused by unbalance in power grid, a Quasi-PR control based selective harmonic compensator is designed. The validity of the proposed control strategy is verified by simulation results.%准比例谐振(quasi-proportion resonant,Quasi-PR)控制器可克服传统比例谐振(proportion resonant,PR)控制器带宽窄、抗频率偏移能力差的缺点,基于此提出了基于三单相Quasi-PR控制的中点箝位式(neutral point clamped,NPC)三电平光伏并网逆变器控制策略。Quasi-PR 控制器继承了传统PR控制器的优点,避免了矢量控制策略中复杂的坐标变换、解耦控制和前馈补偿等,简化了控制算法。同时当电网频率发生偏移时,Quasi-PR 控制器仍能实现对交流电流的无静差跟踪。此外,为减少电网不平衡时产生的较大谐波电流含量,设计了基于Quasi-PR控制的分次谐波补偿器。仿真结果表明了所提控制策略的有效性。

  4. Clinical research of the therapeutic effect of esmolol on refractory ventricular fibrillation occurred after release of aortic cross-clamp during cardiopulmonary bypass%艾司洛尔在体外循环主动脉开放后顽固性室颤中的应用

    Institute of Scientific and Technical Information of China (English)

    王学勇; 程卫平

    2013-01-01

    目的 评价艾司洛尔应用于体外循环主动脉开放后顽固性室颤的临床效果.方法 主动脉开放后出现顽固性室颤的瓣膜置换术患者40例,数字表法随机分为艾司洛尔组和对照组,每组20例.两组患者按照1 mg/kg分别静脉推注艾司洛尔(10 mg/ml)或利多卡因(10 mg/ml),2 min后继续除颤.2次除颤后仍不能复跳者,采取临床其他常月方法处理,直至心脏复跳.记录开放前主动脉阻断时间、肛温、平均动脉压、血乳酸值、血钾值、pH值;给予艾司洛尔或等浓度利多卡因后记录干预后除颤次数、复跳5 min后心律、心率,停机后记录体外循环时间及正性肌力药物用量.结果 两组相比较,艾司洛尔组除颤成功率高,复跳5 min后心率低,体外循环时间短,正性肌力药物用量少,差异均有统计学意义(P<0.05).结论体外循环升主动脉开放后复跳困难的患者,给予艾司洛尔可明显减少除颤次数,提高除颤成功率.同时还可以改善复跳后心脏功能,减少正性肌力药物依赖,缩短体外循环时间.%Objective To evaluate the effect of esmolol on refractory veatricular fibrillation just after aortic declamp during cardiopulmonary bypass.Methods 40 patients undergoing valve replacement occurring refractory ventricular fibrillation after release of aortic cross-clamp was randomly given esmolol (prepared to 10 mg/ml) 1 mg/kg(group esmolol,n =20),or Lidocaine (prepared to 10 mg/ml) 1 mg/kg(group control,n=20),the endocardial electric defibrillation was continued after 2min.If the fibrillation still can not be reversed after another two times defribrillation,the routine clinical method would beused.The time of aortic cross-clamp,rectal temperature,MAP,and the value of serum Lactic acid,potassium,and PH were recorded.After intervention,the times of defibrillation,heart rate and rhythm 5 min after reversal were recorded.At the end of CPB,the CPB time and the dosage of positive inotropic

  5. 利用Botnia钳夹技术评估新简易胰岛素抵抗指数在2型糖尿病患者中与胰岛素抵抗的相关性%Asssessing the correlation of new simple index with insulin resistance in type 2 diabetes by Botnia clamp

    Institute of Scientific and Technical Information of China (English)

    付真真; 顾经宇; 郭雯; 朱晓慧; 高贝贝; 黄晓萍; 袁翠萍; 秦月华; 杨涛

    2013-01-01

    目的:通过Botnia钳夹试验验证简易胰岛素抵抗指数(TyG)在评估2型糖尿病患者胰岛素抵抗中的临床应用价值.方法:共收集43例2型糖尿病受试者,检测空腹血脂谱及其他重要生化指标.所有受试者均行Botnia钳夹试验,并计算葡萄糖代谢率、TyG指数以及HOMA指数、QUICK指数、ISI指数.比较各指数预测评估糖尿病患者胰岛素抵抗的能力.结果:Pearson 相关分析结果显示:TyG指数与Botnia钳夹试验所得葡萄糖代谢率(r=-0.536,P<0.001)、HOMA 1-IR指数(r=0.464,P<0.01)、HOMA2-IR指数(r=0.402,P< 0.01)、QUICK指数(r=-0.448,P< 0.01)、ISI指数(r=-0.464,P< 0.01)均显著相关.以葡萄糖代谢率为标准,绘制ROC曲线,不同指数曲线下面积为TyG(0.879)> HOMA1-IR(0.762)> HOMA2-IR(0.738).TyG指数诊断胰岛素抵抗的最佳值为4.76,此值在ROC曲线中对应了最高的敏感性(96.4%)和特异性(66.7%).结论:TyG指数是较好的评估胰岛素抵抗的简易指数,在2型糖尿病患者中与Botnia钳夹试验所得的葡萄糖代谢率以及HOMA指数、QUICK指数、ISI指数有较好的相关性,较高的敏感度及特异度,且价格低廉临床容易获得,值得推广.%Objective:To investigate the sensitivity and specificity of a new insulin resistance index derived from triglycerides and blood glucose through the Botnia clamp and other simple index in clinical application.Methods:A total of 43 subjects were included in the present study.All the patients underwent Botnia clamp.Lipid profiles and other biochemical markers were measured from the fasting blood sample.Correlation coefficient between insulin resistance index and glucose metabolic rate (M value) were studied.Results:The Pearsons' linear correlation coefficient between TyG and M value (r =-0.536,P < 0.001),HOMA1-IR (r =0.464,P <0.01),HOMA2-IR (r =0.402,P < 0.01),QUICK index(r =-0.448,P < 0.01) and ISI index(r =-0.464,P < 0.01) were statistically significant

  6. Radiofrequency ablation-assisted laparoscopic partial nephrectomy without renal hilar vessel clamping: a report of 14 cases%射频消融辅助下不阻断肾蒂血管行腹腔镜肾部分切除术

    Institute of Scientific and Technical Information of China (English)

    李笑弓; 连惠波; 郭宏骞; 张古田; 张士伟; 屈峰; 姚林方; 杨荣; 汪维

    2011-01-01

    目的 探讨射频消融辅助下不阻断肾蒂血管行腹腔镜肾部分切除术( RF-LCPN)的可行性及临床疗效。方法 2009年1月至2010年6月采用RF-LCPN治疗肾肿瘤14例,共14个肿瘤。肿瘤直径平均3.1(2.2 ~4.0) cm。临床分期均为T1aN0M0。术前常规查血肌酐(SCr)(87±36)μmol/L、患肾肾小球滤过率(GFR) (45±11) ml/min。结果 14例患者手术均成功,平均手术时间( 152±46) min,平均出血量(89±52)rnl,术中快速病理提示标本切缘均阴性。术后出现短暂漏尿1例,通过放置输尿管双J管及留置导尿后治愈。术后平均住院(5±2)d。术后SCr(90±38)μmoI/L,患肾GFR(41±12) ml/min,与术前比较差异无统计学意义(P>0.05)。14例平均随访17(6 ~25)个月。无局部复发或远处转移病例。结论 RF-LCPN安全有效,并能减少肾脏热缺血时间,但远期疗效尚需进一步观察后明确。%ObjectiveTo evaluate the clinical feasibility of radiofrequency ablation-assisted laparoscopic partial nephrectomy(RF-LCPN) without renal hilar vessel clamping. MethodsFrom January 2009 to June 2010, 14 cases with renal tumors were treated with RF-LCPN. The mean tumor size was 3. 1 cm (range: 2. 2-4. 0 cm). All cases were staged at T1a N0M0. The preoperative serum creatinine (SCr)was (87 ± 36) μmol/L and glomerular filtration rate (GFR) (45 ± 11 ) ml/min. ResultsRF-LCPN was technically successful in all patients (14 tumors). The mean operative time was (152 ±4.6) min and the mean blood loss (89 ± 52) ml. All tumor margins were negative. One patient with a brief period of urine leakage from lower pole calix was managed successfully by ureteral stenting and Foley catheter drainage of bladder. The postoperative hospital stay was (5 ± 2 ) days. The postoperative SCr was (90 ± 38 ) μmol/L and GFR (41 ± 12) ml/min. There was no statistic post-operative change of SCr and GFR (P > 0. 05). All patients completed a minimum follow-up of 6 months

  7. Síndrome de compartimento abdominal durante pinçamento por via endoscópica de perfuração intestinal secundária à colonoscopia Síndrome de compartimiento abdominal durante pinzamiento por vía endoscópica de perforación intestinal secundaria a la colonoscopia Abdominal compartment syndrome during endoscopic clamping of an intestinal perforation secondary to colonoscopy

    Directory of Open Access Journals (Sweden)

    Magda Lourenço Fernandes

    2009-10-01

    ópica. El objetivo de este relato de caso, fue avisarles a los expertos sobre el aparecimiento y el tratamiento del síndrome de Compartimiento Abdominal durante el pinzamiento endoscópico de perforación intestinal secundario a la colonoscopia. RELATO DEL CASO: Paciente del sexo femenino, 60 años, estado físico ASA II, sometida a la colonoscopia bajo sedación. Durante el examen se comprobó la perforación accidental del intestino y se optó por tratar de pinzar la perforación por vía endoscópica. La paciente evolucionó con dolor y con una distensión abdominal, neumoperitoneo, síndrome de Compartimiento Abdominal, disnea e inestabilidad cardiovascular. Se realizó la punción abdominal de emergencia, lo que determinó la mejoría clínica de la paciente hasta que se hiciese la laparotomía de urgencia. Después de realizarla con exploración y con sutura de la perforación, la paciente evolucionó bien clínicamente. CONCLUSIONES: El pinzamiento por vía endoscópica de perforación intestinal secundaria a la colonoscopia, puede contribuir a la formación de neumoperitoneo hipertensivo y el síndrome de Compartimiento Abdominal, con repercusiones clínicas graves que exigen un tratamiento inmediato. Los profesionales capacitados y los recursos técnicos adecuados, pueden ser factores determinantes del pronóstico del paciente.BACKGROUND AND OBJECTIVES: Colonoscopy is widely used for diagnosis, treatment, and control of intestinal disorders. Intestinal perforation, although rare, is the most feared complication. Perforations can be treated by endoscopic clamping. The objective of this report was to alert specialists for the development and treatment of abdominal compartment syndrome during endoscopic clamping of an intestinal perforation secondary to colonoscopy. CASE REPORT: This is a 60 years old female, physical status ASA II, who underwent colonoscopy under sedation. During the exam, an accidental intestinal perforation was observed, and it was decided to

  8. Expression of Kir2.1, SCN5a and SCN1b channel genes in mouse cardiomyocytes with various electric properties: patch clamp combined with single cell RT-PCR study%小鼠不同电特性的心肌细胞Kir2.1、SCN5a和SCN1b通道基因的表达:膜片钳结合单细胞RT-PCR技术研究

    Institute of Scientific and Technical Information of China (English)

    骆红艳; 梁华敏; 胡新武; 唐明

    2012-01-01

    This study is to explore a new method of investigating molecular basis for electrophysiological properties of early fetal car-diomyocytes. Single embryonic cardiomyocytes of mouse early developmental heart (E10.5) were obtained by a collagenase B digestion approach. After recording spontaneous action potential using whole cell patch clamp technique, the single cell was picked by a glass micropipette, followed by a standard RT-PCR to explore the expression levels of several ion channel genes. Three phenotypes of cardiomyocytes were demonstrated with distinct properties: ventricular-like, atrial-like, and pacemaker-like action potentials. Ventric-ular-like and atrial-like cells were characterized with much negative maximum diastolic potential (MDP) and a higher I/max (maximum velocity of depolarization) compared to pacemaker-like cells. MDP of ventricular-like cells was the most negative. In parallel, stronger expression of SCN5a, SCN1b and Kir2.1 were observed in ventricular-like and atrial-like cells compared to that of pacemaker-like cells, where Kir2.1 in ventricular-like cells was the most abundant. Cardiomyocytes with distinct electrophysiological properties had distinct gene expression pattern. Single cell RT-PCR combined with patch clamp technique could serve as a precise detector to analyze the molecular basis of the special electrophysiological characteristics of cardiomyocytes.%本文旨在应用膜片钳技术结合单细胞逆转录聚合酶链反应(reverse transcriptase polymerase chain reaction,RT-PCR)技术研究小鼠胚胎心肌细胞的不同电生理学特点的分子生物学基础.应用胶原酶B消化分离得到小鼠胚胎早期(E10.5)单个心肌细胞,先用膜片钳技术记录单个胚胎心肌细胞的动作电位,随即应用玻璃微电极吸取该细胞内容物,进一步应用RT-PCR技术检测该单个心肌细胞离子通道基因Kir2.1、SCN5a和SCNlb的表达,以GAPDH为内参基因.全细胞电流钳技术记录到心室肌

  9. 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.

  10. Measurement of voltage dependence of capacitance of planar bilayer lipid membrane with a patch clamp amplifier.

    OpenAIRE

    Toyama, S.; Nakamura, A; Toda, F

    1991-01-01

    The voltage dependence of capacitance was measured by using the setup which was almost the same as that for the study of ion channels. The coefficient which represents the voltage dependence of capacitance itself also changes as a function of the duration of voltage application if hexadecane is contained in bilayer lipid membrane (BLM). The method of Alvarez, O., and R. Latorre (1978. Biophys. J. 21:1-17) was extended to treat BLM with hexadecane.

  11. Angiotensin II clamp prevents the second step in renal apical NHE3 internalization during acute hypertension

    DEFF Research Database (Denmark)

    Leong, Patrick K K; Yang, Li E; McDonough, Alicia A;

    2002-01-01

    Acute hypertension inhibits proximal tubule (PT) sodium reabsorption. The resultant increase in NaCl delivery to the macula densa suppresses renin release. We tested whether the sustained pressure-induced inhibition of PT sodium reabsorption requires a renin-mediated decrease in ANG II levels...... hypertension, including diuresis and redistribution of PT NHE3 into intracellular membranes, require a responsive renin-angiotensin system and that the responses may be induced by the sustained increase in NaCl delivery to the macula densa during acute hypertension....

  12. A Rigorous Derivation of the Equations for the Clamped Biot-Kirchhoff-Love Poroelastic plate

    CERN Document Server

    Marciniak-Czochra, Anna

    2012-01-01

    In this paper we investigate the limit behavior of the solution to quasi-static Biot's equations in thin poroelastic plates as the thickness tends to zero. We choose Terzaghi's time corresponding to the plate thickness and obtain the strong convergence of the three-dimensional solid displacement, fluid pressure and total poroelastic stress to the solution of the new class of plate equations. In the new equations the in-plane stretching is described by the 2D Navier's linear elasticity equations, with elastic moduli depending on Gassmann's and Biot's coefficients. The bending equation is coupled with the pressure equation and it contains the bending moment due to the variation in pore pressure across the plate thickness. The pressure equation is parabolic only in the vertical direction. As additional terms it contains the time derivative of the in-plane Laplacean of the vertical deflection of the plate and of the the elastic in-plane compression term.

  13. [Completion pneumonectomy combined with graft replacement of thoracic aortic aneurysm by simple clamping].

    Science.gov (United States)

    Shimamoto, A; Takao, M; Kanemitsu, S; Fujinaga, K; Yan, G; Cruz, B P; Onoda, K; Shimono, T; Shimpo, H; Namikawa, S; Yuasa, H; Yada, I

    1999-01-01

    A 59-years-old male patient who had left upper lobe partial resection 30 years ago. He was seen at the family physician because of cough. A chest X-ray was showing an abnormal mass shadow measuring 3 x 4 cm in left lower lobe like honey comb. And squamous cell carcinoma (SCC) was detected in his sputum. He was diagnosed as primary lung cancer and introduced to our department to have operation. Chest CT-scan was showing lung tumor suspected SCC measuring 4.3 x 2.6 cm in segment 8 faced chest wall. At the same time, we detected thoracic aortic aneurysm and subcarinal lymph node, but could not see where the boundary is, so it was hard to distinguish between parietal thrombus with thoracic aortic aneurysm and swelling subcarinal lymph node. We decided it swelling subcarinal lymph node by three-dimensional treated CT-scan. Aortic angiography was showing proximal descending aortic aneurysm measuring diameter was 4.5 cm. Abdominal CT-scan was showing infrarenal abdominal aortic aneurysm measuring diameter was 5.5 cm. He was diagnosed as primary lung cancer (It. S8, SCC) (cT2N2M0, Stage IIIB), thoracic aortic aneurysm, abdominal aortic aneurysm, and idiopathic pulmonary fibrosis, and had completion pneumonectomy (R 2 b) for primary lung cancer and graft replacement with aneurysm dissection for thoracic aortic aneurysm without extracorporeal circulation. In this operation, we could find swelling subcarinal lymph node measuring 5 x 3 cm instead of parietal thrombus with thoracic aortic aneurysm. Pathological examination diagnosed middle differential SCC and no metastasis from dissected lymph node (PT2N0M0, Stage I A). PMID:10024802

  14. Nanoscale-Targeted Patch-Clamp Recordings of Functional Presynaptic Ion Channels

    OpenAIRE

    Novak, Pavel; Gorelik, Julia; Vivekananda, Umesh; Shevchuk, Andrew I.; Ermolyuk, Yaroslav S.; Bailey, Russell J.; Bushby, Andrew J.; Moss, Guy W.J.; Rusakov, Dmitri A.; Klenerman, David; Kullmann, Dimitri M.; Volynski, Kirill E.; Korchev, Yuri E.

    2013-01-01

    Summary Direct electrical access to presynaptic ion channels has hitherto been limited to large specialized terminals such as the calyx of Held or hippocampal mossy fiber bouton. The electrophysiology and ion-channel complement of far more abundant small synaptic terminals (≤1 μm) remain poorly understood. Here we report a method based on superresolution scanning ion conductance imaging of small synapses in culture at approximately 100–150 nm 3D resolution, which allows presynaptic patch-clam...

  15. Peripheral nerve function during hyperglycemic clamping in insulin-dependent diabetic patients

    DEFF Research Database (Denmark)

    Sindrup, S H; Ejlertsen, B; Gjessing, H; Svendsen, Anders Jørgen; Frøland, A

    1989-01-01

    The influence of hyperglycemia on peripheral nerve function was studied in 9 patients with long-term insulin-dependent diabetes. Blood glucose concentration was raised 13.5 +/- 0.5 mmol/l (mean +/- SEM) within 15 min and kept approximately 15 mmol/l over basal level for 120 min by intravenous...... glucose infusion. Hyperglycemia was accompanied by increased plasma osmolality. Sensory and motor nerve conduction and distal motor latency in the ulnar nerve were determined before, immediately after induction of hyperglycemia, and again after 120 min hyperglycemia. Distal (5th finger - wrist) and...... proximal (wrist - elbow) sensory nerve conduction showed an insignificant increase as hyperglycemia was induced. During hyperglycemia mean distal sensory conduction decreased from 53.1 m/s to 50.4 m/s (P less than 0.05) and mean proximal sensory conduction decreased from 56.0 m/s to 54.2 m/s (P less than 0...

  16. Eliminating flutter for clamped von Karman plates immersed in subsonic flows

    OpenAIRE

    Lasiecka, Irena; Webster, Justin T.

    2014-01-01

    We address the long-time behavior of a non-rotational von Karman plate in an inviscid potential flow. The model arises in aeroelasticity and models the interaction between a thin, nonlinear panel and a flow of gas in which it is immersed [6, 21, 23]. Recent results in [16, 18] show that the plate component of the dynamics (in the presence of a physical plate nonlinearity) converge to a global compact attracting set of finite dimension; these results were obtained in the absence of mechanical ...

  17. Voltage clamp analysis of ajmaline-induced block of potassium currents in ventricular myocytes

    Czech Academy of Sciences Publication Activity Database

    Bahníková, M.; Matějovič, P.; Pásek, Michal; Šimurdová, M.; Šimurda, J.

    Brno : Brno University of Technology, 2002 - (Jan, J.; Kozumplík, J.; Provazník, I.), s. 217-219 ISBN 80-214-2633-0. ISSN 1211-412X. [Biosignal 2002. Brno (CZ), 26.06.2002-28.06.2002] Institutional research plan: CEZ:AV0Z2076919 Keywords : cardiac cell * potassium currents * ajmaline Subject RIV: BO - Biophysics

  18. Density clamping phenomena in electron cyclotron resonance heated plasmas on Heliotron E

    International Nuclear Information System (INIS)

    Particle transport and related phenomena are investigated in currentless electron cyclotron resonance heated plasmas. It is observed that during the initial phase the density stops rising and then starts to decay, in spite of continuous gas puffing. The delay time between the breakdown time and the time at which the density starts to decay depends inversely on rf power. The density profile changes drastically, becoming flat or hollow at this time. This density profile change becomes more significant as the rf power is increased. In order to sustain the density at some level the external particle source should be increased with increasing rf power. Here it is found that the particle confinement time decreases with increasing power. The substantial increase in the particle outflux from the main plasma causes the scrape-off plasma to have a steep gradient. As a result, the amplitudes of density and magnetic fluctuations are enhanced with increasing rf power. When the cyclotron resonance layer is shifted outside the half radius, it is found that the density profile changes from hollow to centrally peaked. This result shows that the density profile is a function of the power deposition profile. It is also shown that the behavior of impurity ions (injected by the laser blow-off technique) is similar to that of the bulk particles. (author)

  19. Optimization of all-optical gain-clamped lumped Raman fibre amplifier for dynamic performance

    Czech Academy of Sciences Publication Activity Database

    Karásek, Miroslav; Kaňka, Jiří; Radil, J.

    Vol. 1. Piscataway: Institute of Electrical and Electronic Engineers, 2005 - (Marciniak, M.), s. 43-45 ISBN 0-7803-9236-1. [International Conference on Transparent Optical Networks ICTON'2005 /7./ collocated with European Symposium on Photonic Crystals ESPC /4./, Workshop on All-Optical Routing WAOR /4./, Global Optical & Wireless Networking GOWN Seminar /2./, COST 270 Workshop on Reliability Issues in Next Generation Optical Networks RONEXT, Photonic Integrated Components & Applications Workshop PICAW, COST 291 Workshop on Issues and Challenges in Optical Networking and "e-Photon/ONe" Special Session. Barcelona (ES), 03.07.2005-07.07.2005] R&D Projects: GA MŠk(CZ) 1P05OC001 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical communication * amplifiers * wavelength division multiplexing Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  20. Tetramethylpyrazine attenuates spinal cord ischemic injury due to aortic cross-clamping in rabbits

    Directory of Open Access Journals (Sweden)

    Dong Hailong

    2002-04-01

    Full Text Available Abstract Background Lower limb paralysis occurs in 11% of patients after surgical procedure of thoracic or thoracoabdominal aneurysms and is an unpredictable and distressful complication. The aim of this study was to investigate the effects of tetramethylpyrazine (TMP, an intravenous drug made from traditional Chinese herbs, on the neurologic outcome and hisotpathology after transient spinal cord ischemia in rabbits. Methods Forty-five male New Zealand white rabbits were anesthetized with isoflurane and spinal cord ischemia was induced for 20 min by infrarenal aortic occlusion. Animals were randomly allocated to one of five groups (n = 8 each. Group C received no pharmacologic intervention. Group P received intravenous infusion of 30 mg·kg-1 TMP within 30 min before aortic occlusion. Group T1, Group T2 and Group T3 received intravenous infusion of 15, 30 and 60 mg·kg-1 TMP respectively within 30 min after reperfusion. In the sham group (n = 5, the animals underwent the same procedures as the control group except infrarental aortic unocclusion. Neurologic status was scored by using the Tarlov criteria (in which 4 is normal and 0 is paraplegia at 4 h, 8 h, 12 h, 24 h, and 48 h after reperfusion. All animals were sacrificed at 48 h after reperfusion and the spinal cords (L5 were removed immediately for histopathologic study. Results All animals in the control group became paraplegic. Neurologic status and histopathology (48 h in the Groups P, T2 and T3 were significantly better than those in the control group (P r = 0.776, P Conclusion Tetramethylpyrazine significantly reduces neurologic injury related to spinal cord ischemia and reperfusion after aortic occlusion within a certain range of dose.