Science.gov

Sample records for 4-channel surface coils

  1. Concentric Loop Surface Coil

    NASA Astrophysics Data System (ADS)

    Hernández-Flores, R.; Rodríguez-González, A. O.; Salgado-Lujambio, P.; Barrios-Alvarez, F. A.

    2002-08-01

    A surface coil for MRI consisted of two concentric loops was developed for brain imaging. Prior to build the coil prototype, the magnetic field (B1) generated by the coil was numerically simulated. This field simulation is based on the Biot-Savart law for the circular- and square-shaped loops. From these theoretical results, we can appreciate an improvement on the B1 homogeneity. Brain images obtained at 1.5 Tesla show a good sensitivity in a particular region of interest. Also, these images compared well against images obtained with a circular-shaped coil. This receiver coil can generate high quality brain images.

  2. A 4-channel 3 Tesla phased array receive coil for awake rhesus monkey fMRI and diffusion MRI experiments.

    PubMed

    Khachaturian, Mark Haig

    2010-01-01

    Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4-8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic).

  3. Magnetron surface coil for brain MR imaging.

    PubMed

    Rodríguez, Alfredo O

    2006-08-01

    A resonator surface coil was developed for magnetic resonance imaging of the brain and tested on a clinical imager. This resonator design was based on the cavity magnetron with an 8 slot-and-hole configuration. High-resolution brain images were obtained from a water-filled phantom and from a healthy volunteer brain. To compare coil performance, SNR-vs.-depth plots were computed for a single-loop coil and the magnetron prototype from phantom images. These experimentally acquired profiles show an important improvement in SNR. Thus, the magnetron surface coil can generate brain images with a high resolution and penetration capacity. The high sensitivity of this coil makes it a good candidate to be used in multicoil imaging sequences.

  4. [Surface coils for magnetic-resonance images].

    PubMed

    Rodríguez-González, Alfredo Odón; Amador-Baheza, Ricardo; Rojas-Jasso, Rafael; Barrios-Alvarez, Fernando Alejandro

    2005-01-01

    Since the introduction of magnetic resonance imaging in Mexico, the development of this important medical imaging technology has been almost non-existing in our country. The very first surface coil prototypes for clinical applications in magnetic resonance imaging has been developed at the Center of Research in Medical Imaging and Instrumentation of the Universidad Autónoma Metropolitana Iztapalapa (Metropolitan Autonomous University, Campus Iztapalapa). Two surface coil prototypes were built: a) a circular-shaped coil and b) a square-shaped coil for multiple regions of the body, such as heart, brain, knee, hands, and ankles. These coils were tested on the 1.5T imager of the ABC Hospital-Tacubaya, located in Mexico City. Brain images of healthy volunteers were obtained in different orientations: sagittal, coronal, and axial. Since images showed a good-enough clinical quality for diagnosis, it is fair to say that these coil prototypes can be used in the clinical environment, and with small modifications, they can be made compatible with almost any commercial scanner. This type of development can offer new alternatives for further collaboration between the research centers and the radiology community, in the search of new applications and developments of this imaging technique.

  5. Experimental development of a petal resonator surface coil.

    PubMed

    Rodríguez, Alfredo Odon; Hidalgo, Sandra Silvia; Rojas, Rafael; Barrios, Fernando Alejandro

    2005-12-01

    A surface coil for MRI was designed and built based on the principles of the petal resonator proposed by Mansfield [J Phys D Appl Phys 21 (1988) 1643]. This resonator coil design was named the petal resonator surface (PERES) coil and is composed of an eight-petal coil array and a central circular coil. A minimum separation of three times the petal coil radius is necessary to significantly decrease the mutual inductance. An analytical function for the PERES Signal-to-noise ratio (SNR) is obtained based on the quasistatic method. Theoretical plots of SNR enhancement yielded 26% and 35% more SNR over the circular coil and phased-array coils. Imaging experiments were first performed using a spectroscopy phantom on a 1.5-T commercial imager. Subsequently, brain images of healthy volunteers were obtained. Clinical MR imager compatibility allows this resonator coil to be used with conventional pulse sequences and imaging protocols. This coil design offers a new alternative to existing surface coils because it significantly increases the SNR.

  6. Investigating a Quadrant Surface Coil Array for NQR Remote Sensing

    DTIC Science & Technology

    2014-10-23

    UNCLASSIFIED 1  Abstract—this paper is on the design and fabrication of a surface coil array in a quadrant layout for NQR (Nuclear Quadrupole...coupling and SNR (Signal-to-Noise Ratio) at standoff distances perpendicular from each coil. Index Terms— Nuclear Quadrupole Resonance, NQR ...Coil Array, probe, Nuclear Magnetic Resonance, tuning, decoupling, RLC, mutual coupling, RLC I. INTRODUCTION N Nuclear quadrupole resonance ( NQR

  7. MRI surface-coil pair with strong inductive coupling.

    PubMed

    Mett, Richard R; Sidabras, Jason W; Hyde, James S

    2016-12-01

    A novel inductively coupled coil pair was used to obtain magnetic resonance phantom images. Rationale for using such a structure is described in R. R. Mett et al. [Rev. Sci. Instrum. 87, 084703 (2016)]. The original rationale was to increase the Q-value of a small diameter surface coil in order to achieve dominant loading by the sample. A significant improvement in the vector reception field (VRF) is also seen. The coil assembly consists of a 3-turn 10 mm tall meta-metallic self-resonant spiral (SRS) of inner diameter 10.4 mm and outer diameter 15.1 mm and a single-loop equalization coil of 25 mm diameter and 2 mm tall. The low-frequency parallel mode was used in which the rf currents on each coil produce magnetic fields that add constructively. The SRS coil assembly was fabricated and data were collected using a tissue-equivalent 30% polyacrylamide phantom. The large inductive coupling of the coils produces phase-coherency of the rf currents and magnetic fields. Finite-element simulations indicate that the VRF of the coil pair is about 4.4 times larger than for a single-loop coil of 15 mm diameter. The mutual coupling between coils influences the current ratio between the coils, which in turn influences the VRF and the signal-to-noise ratio (SNR). Data on a tissue-equivalent phantom at 9.4 T show a total SNR increase of 8.8 over the 15 mm loop averaged over a 25 mm depth and diameter. The experimental results are shown to be consistent with the magnetic resonance theory of the emf induced by spins in a coil, the theory of inductively coupled resonant circuits, and the superposition principle. The methods are general for magnetic resonance and other types of signal detection and can be used over a wide range of operating frequencies.

  8. Coil Tolerance Impact on Plasma Surface Quality for NCSX

    SciTech Connect

    Art Brooks; Wayne Reiersen

    2003-10-20

    The successful operation of the National Compact Stellarator Experiment (NCSX) machine will require producing plasma configurations with good flux surfaces, with a minimum volume of the plasma lost to magnetic islands or stochastic regions. The project goal is to achieve good flux surfaces over 90% of the plasma volume. NCSX is a three period device designed to be operated with iota ranging from {approx}0.4 on axis to {approx}0.7 at the edge. The field errors of most concern are those that are resonant with 3/5 and 3/6 modes (for symmetry preserving field errors) and the 1/2 and 2/3 modes (for symmetry breaking field errors). In addition to losses inherent in the physics configuration itself, there will be losses from field errors arising from coil construction and assembly errors. Some of these losses can be recovered through the use of trim coils or correction coils. The impact of coil tolerances on plasma surface quality is evaluated herein for the NCSX design. The methods used in this evaluation are discussed. The ability of the NCSX trim coils to correct for field errors is also examined. The results are used to set coils tolerances for the various coil systems.

  9. NMR of thin layers using a meanderline surface coil

    DOEpatents

    Cowgill, Donald F.

    2001-01-01

    A miniature meanderline sensor coil which extends the capabilities of nuclear magnetic resonance (NMR) to provide analysis of thin planar samples and surface layer geometries. The sensor coil allows standard NMR techniques to be used to examine thin planar (or curved) layers, extending NMRs utility to many problems of modern interest. This technique can be used to examine contact layers, non-destructively depth profile into films, or image multiple layers in a 3-dimensional sense. It lends itself to high resolution NMR techniques of magic angle spinning and thus can be used to examine the bonding and electronic structure in layered materials or to observe the chemistry associated with aging coatings. Coupling this sensor coil technology with an arrangement of small magnets will produce a penetrator probe for remote in-situ chemical analysis of groundwater or contaminant sediments. Alternatively, the sensor coil can be further miniaturized to provide sub-micron depth resolution within thin films or to orthoscopically examine living tissue. This thin-layer NMR technique using a stationary meanderline coil in a series-resonant circuit has been demonstrated and it has been determined that the flat meanderline geometry has about he same detection sensitivity as a solenoidal coil, but is specifically tailored to examine planar material layers, while avoiding signals from the bulk.

  10. Application of anatomically shaped surface coils in MRI at 0.5 T.

    PubMed

    Doornbos, J; Grimbergen, H A; Booijen, P E; te Strake, L; Bloem, J L; Vielvoye, G J; Boskamp, E

    1986-04-01

    The construction and application of eight different MRI surface coils is described. The coils consist of an anatomically shaped copper wire loop as an antenna and a printed circuit board containing electronic components for tuning and matching. The electronic device for tuning and matching is interchangeable between the various coils. Surface coils for signal detection yield images with high signal-to-noise ratio in comparison to the usual saddle-shaped head or body coils. The sensitivity of a surface coil decreases with increasing distance between the coil and the object of interest and therefore the coils are constructed to fit the anatomical structure under examination as well as possible. The application of dedicated surface coils for superficial structures in the body extends the possibilities of the MRI system. Photographs of the coils positioned on the body and MR images of volunteers and patients are shown.

  11. Surface coil magnetic resonance imaging of the normal larynx.

    PubMed

    McArdle, C B; Bailey, B J; Amparo, E G

    1986-06-01

    The use of specialized surface coils has made it possible to obtain high-signal, high-resolution magnetic resonance (MR) images of the neck. We describe the normal anatomy of the larynx imaged with surface coils and a technique adapted from respiratory gating to reduce motion from swallowing and coughing. Compared with computed tomography, MR has superior discrimination of tissues that on computed tomography appear to be of similar density. The intrinsic laryngeal muscles and carotid sheath are well seen. Multiplanar imaging capability allows easy distinction of false and true cords and optimal evaluation of the preepiglottic and paralaryngeal spaces. Computed tomography is easier to perform than MR and is superior to MR in depicting the laryngeal cartilages. However, with improved technology, MR may become the imaging modality of choice in evaluation of the larynx and adjacent hypopharynx and subglottic regions.

  12. A multi-slot surface coil for MRI of dual-rat imaging at 4 T

    NASA Astrophysics Data System (ADS)

    Solis, S. E.; Wang, R.; Tomasi, D.; Rodriguez, A. O.

    2011-06-01

    A slotted surface coil inspired by the hole-and-slot cavity magnetron was developed for magnetic resonance imaging of obese rats at 4 T. Full-wave analysis of the magnetic field was carried out at 170 MHz for both the slotted and circular-shaped coils. The noise figure values of two coils were investigated via the numerical calculation of the quality factors. Fat simulated phantoms to mimic overweight rats were included in the analysis with weights ranging from 300 to 900 g. The noise figures were 1.2 dB for the slotted coil and 2.4 dB for the circular coil when loaded with 600 g of simulated phantom. A slotted surface coil with eight circular slots and a circular coil with similar dimensions were built and operated in the transceiver mode, and their performances were experimentally compared. The imaging tests in phantoms demonstrated that the slotted surface coil has a deeper RF-sensitivity and better field uniformity than the single-loop RF-coil. High quality images of two overweight Zucker rats were acquired simultaneously with the slotted surface coil using standard spin-echo pulse sequences. Experimental results showed that the slotted surface coil outperformed the circular coil for imaging considerably overweight rats. Thus, the slotted surface coil can be a good tool for MRI experiments in rats on a human whole-body 4 T scanner.

  13. A multi-slot surface coil for MRI of dual-rat imaging at 4T

    SciTech Connect

    Solis, S.E.; Tomasi, D.; Solis, S.E.; Wang, R.; Tomasi, D.; Rodriguez, A.O.

    2011-07-01

    A slotted surface coil inspired by the hole-and-slot cavity magnetron was developed for magnetic resonance imaging of obese rats at 4 T. Full-wave analysis of the magnetic field was carried out at 170 MHz for both the slotted and circular-shaped coils. The noise figure values of two coils were investigated via the numerical calculation of the quality factors. Fat simulated phantoms to mimic overweight rats were included in the analysis with weights ranging from 300 to 900 g. The noise figures were 1.2 dB for the slotted coil and 2.4 dB for the circular coil when loaded with 600 g of simulated phantom. A slotted surface coil with eight circular slots and a circular coil with similar dimensions were built and operated in the transceiver mode, and their performances were experimentally compared. The imaging tests in phantoms demonstrated that the slotted surface coil has a deeper RF-sensitivity and better field uniformity than the single-loop RF-coil. High quality images of two overweight Zucker rats were acquired simultaneously with the slotted surface coil using standard spin-echo pulse sequences. Experimental results showed that the slotted surface coil outperformed the circular coil for imaging considerably overweight rats. Thus, the slotted surface coil can be a good tool for MRI experiments in rats on a human whole-body 4 T scanner.

  14. Microstrip RF surface coil design for extremely high-field MRI and spectroscopy.

    PubMed

    Zhang, X; Ugurbil, K; Chen, W

    2001-09-01

    A new type of high-frequency RF surface coil was developed for in vivo proton or other nuclei NMR applications at 7T. This is a purely distributed-element and transmission line design. The coil consists of a thin strip conductor (copper or silver) and a ground plane separated by a low-loss dielectric material with a thickness (H). Due to its specific semi-open transmission line structure, substantial electromagnetic energy is stored in the dielectric material between the thin conductor and the ground plane, which results in a reduced radiation loss and a reduced perturbation of sample loading to the RF coil compared to conventional surface coils. The coil is characterized by a high Q factor, no RF shielding, small physical coil size, lower cost, and easy fabrication. A brief theoretical description of the microstrip RF coil is given that can be used to guide the coil designs. A set of gradient-recalled echo images were acquired by using the single- and two-turn microstrip RF surface coils from both phantom and human brain at 7T, which show good penetration and sensitivity. The two-turn coil design significantly improves the B1 symmetry as predicted by the microstrip theory. The optimum H for microstrip surface coils is approximately 7 mm. This coil geometry yields a B1 penetration similar to that of conventional surface coils. SNR comparison was made between the microstrip coil and conventional surface coils with and without RF shielding. The results reveal that the novel surface coil design based on the microstrip concept makes very high-field MRI/MRS more convenient and efficient in research and future clinics.

  15. Locating Materials with Nuclear Quadrupole Moments within Surface Coil Array Area

    DTIC Science & Technology

    2015-08-11

    28.1MHz NQR frequency from potassium chlorate (PC) sample at room temperature. The PC sample will be in different locations parallel to the surface...using the experimental results from the dual surface coil array. 15. SUBJECT TERMS NQR, potassium chlorate , surface coil, surface probe, decoupling... chlorate (PC) sample at room temperature. The PC sample will be in different locations parallel to the surface plane of two tuned coils at a

  16. A comparison of double-tuned surface coils.

    PubMed

    Fitzsimmons, J R; Brooker, H R; Beck, B

    1989-06-01

    The combined acquisition of proton images and localized spectra is considered essential to the practical application of NMR techniques to human and animal research. Double-tuned surface coils which have been introduced to the literature are intended to address the problem; however, a careful evaluation of available designs is lacking. The "trap" method, the loop gap resonator design, and the transformer-coupled double-tuned design are evaluated here using bench tests of signal intensity and Q as well as signal-to-noise measurements on a 2-T imager/spectrometer. Comparisons are made relative to optimized single-tuned circuits of the same size for both protons at 85 MHz and phosphorus at 34 MHz. The results suggest that the "trap" design and the transformer coupled design are very efficient (98%) in the low-frequency mode (34 MHz) while the loop gap resonator is relatively inefficient (82%). In the high-frequency mode (85 MHz) the loop gap resonator is 75% efficient while the "trap" design and the transformer coupled coil are closer to 50% efficient.

  17. Two-Slotted Surface Coil Array for Magnetic Resonance Imaging at 4 Tesla

    SciTech Connect

    Solis, S. E.; Hernandez, J. A.; Rodriguez, A. O.; Tomasi, D.

    2008-08-11

    Arrays of antennas have been widely accepted for magnetic resonance imaging applications due to their high signal-to-noise ratio (SNR) over large volumes of interest. A new surface coil based on the magnetron tube and called slotted surface coil, has been recently introduced by our group. This coil design experimentally demonstrated a significant improvement over the circular-shaped coil when used in the receive-only mode. The slotted coils formed a two-sheet structure with a 90 deg. separation and each coil had 6 circular slots. Numerical simulations were performed using the finite element method for this coil design to study the behaviour of the array magnetic field. Then, we developed a two-coil array for brain magnetic resonance imaging to be operated at the resonant frequency of 170 MHz in the transceiver mode. Phantom images were acquired with our coil array and standard pulse sequences on a research-dedicated 4 Tesla scanner. Numerical simulations demonstrated that electromagnetic interaction between the coil elements is negligible, and that the magnetic field showed a good uniformity. In vitro images showed the feasibility of this coil array for standard pulses for high field magnetic resonance imaging.

  18. Comparison and evaluation of mouse cardiac MRI acquired with open birdcage, single loop surface and volume birdcage coils.

    PubMed

    Fan, Xiaobing; Markiewicz, Erica J; Zamora, Marta; Karczmar, Gregory S; Roman, Brian B

    2006-12-21

    Although the quality and speed of MR images have vastly improved with the development of novel RF coil technologies, the engineering expertise required to implement them is often not available in many animal in vivo MR laboratories. We present here an open birdcage coil design which is easily constructed with basic RF coil expertise and produces high quality images. The quality and advantages of mouse cardiac MR images acquired with open birdcage coils were evaluated and compared to images acquired with a bent single loop surface, and standard birdcage coils acquired at 4.7 Tesla. Two low pass open birdcage coils, two single loop surface coils, and a low pass volume birdcage coil were constructed and their B(1) distributions were evaluated and compared. The calculated average signal-to-noise ratio for the left ventricular wall was 10, 23 and 32 for the volume birdcage coil, single loop surface coil and open birdcage coil, respectively. The results demonstrate that the open birdcage coil provides greater sensitivity than the volume coil and a higher signal/contrast-to-noise ratio and B(1) homogeneity than the single loop surface coil. The open birdcage coil offers easy access and better quality mouse cardiac imaging than both the single loop surface coil and volume birdcage coil and does not require extensive RF engineering expertise to construct.

  19. NOTE: Comparison and evaluation of mouse cardiac MRI acquired with open birdcage, single loop surface and volume birdcage coils

    NASA Astrophysics Data System (ADS)

    Fan, Xiaobing; Markiewicz, Erica J.; Zamora, Marta; Karczmar, Gregory S.; Roman, Brian B.

    2006-12-01

    Although the quality and speed of MR images have vastly improved with the development of novel RF coil technologies, the engineering expertise required to implement them is often not available in many animal in vivo MR laboratories. We present here an open birdcage coil design which is easily constructed with basic RF coil expertise and produces high quality images. The quality and advantages of mouse cardiac MR images acquired with open birdcage coils were evaluated and compared to images acquired with a bent single loop surface, and standard birdcage coils acquired at 4.7 Tesla. Two low pass open birdcage coils, two single loop surface coils, and a low pass volume birdcage coil were constructed and their B1 distributions were evaluated and compared. The calculated average signal-to-noise ratio for the left ventricular wall was 10, 23 and 32 for the volume birdcage coil, single loop surface coil and open birdcage coil, respectively. The results demonstrate that the open birdcage coil provides greater sensitivity than the volume coil and a higher signal/contrast-to-noise ratio and B1 homogeneity than the single loop surface coil. The open birdcage coil offers easy access and better quality mouse cardiac imaging than both the single loop surface coil and volume birdcage coil and does not require extensive RF engineering expertise to construct.

  20. Slotted surface coil with reduced g-factor for SENSE imaging.

    PubMed

    Ocegueda, K; Rodriguez, A O

    2006-01-01

    A new coil design inspired on the slot-and-hole magnetron tube is proposed for SENSE imaging. To investigate its g-factor behaviour: an SNR formula was derived using the quasi-static approach, and combined with the ultimate g-factor formula to compute the ultimate-factor-g-vs-depth plots. A g-factor expression was derived for the circular coil using the same approach for comparison purposes. SNR-vs-depth profiles of an 4-slot coil showed an important improvement over the circular coil. The 4-slot coil g-factor can be up to 58.32% lower than that of a single circular-shaped coil. This improvement makes the slotted surface coil a good choice for SENSE imaging.

  1. Four-channel surface coil array for sequential CW-EPR image acquisition

    NASA Astrophysics Data System (ADS)

    Enomoto, Ayano; Emoto, Miho; Fujii, Hirotada; Hirata, Hiroshi

    2013-09-01

    This article describes a four-channel surface coil array to increase the area of visualization for continuous-wave electron paramagnetic resonance (CW-EPR) imaging. A 776-MHz surface coil array was constructed with four independent surface coil resonators and three kinds of switches. Control circuits for switching the resonators were also built to sequentially perform EPR image acquisition for each resonator. The resonance frequencies of the resonators were shifted using PIN diode switches to decouple the inductively coupled coils. To investigate the area of visualization with the surface coil array, three-dimensional EPR imaging was performed using a glass cell phantom filled with a solution of nitroxyl radicals. The area of visualization obtained with the surface coil array was increased approximately 3.5-fold in comparison to that with a single surface coil resonator. Furthermore, to demonstrate the applicability of this surface coil array to animal imaging, three-dimensional EPR imaging was performed in a living mouse with an exogenously injected nitroxyl radical imaging agent.

  2. ANALYSES AND COMPARISON OF BULK AND COIL SURFACE SAMPLES FROM THE DWPF SLURRY MIX EVAPORATOR

    SciTech Connect

    Hay, M.; Nash, C.; Stone, M.

    2012-02-17

    Sludge samples from the DWPF Slurry Mix Evaporator (SME) heating coil frame and coil surface were characterized to identify differences that might help identify heat transfer fouling materials. The SME steam coils have seen increased fouling leading to lower boil-up rates. Samples of the sludge were taken from the coil frame somewhat distant from the coil (bulk tank material) and from the coil surface (coil surface sample). The results of the analysis indicate the composition of the two SME samples are very similar with the exception that the coil surface sample shows {approx}5-10X higher mercury concentration than the bulk tank sample. Elemental analyses and x-ray diffraction results did not indicate notable differences between the two samples. The ICP-MS and Cs-137 data indicate no significant differences in the radionuclide composition of the two SME samples. Semi-volatile organic analysis revealed numerous organic molecules, these likely result from antifoaming additives. The compositions of the two SME samples also match well with the analyzed composition of the SME batch with the exception of significantly higher silicon, lithium, and boron content in the batch sample indicating the coil samples are deficient in frit relative to the SME batch composition.

  3. Markerless attenuation correction for carotid MRI surface receiver coils in combined PET/MR imaging

    NASA Astrophysics Data System (ADS)

    Eldib, Mootaz; Bini, Jason; Robson, Philip M.; Calcagno, Claudia; Faul, David D.; Tsoumpas, Charalampos; Fayad, Zahi A.

    2015-06-01

    The purpose of the study was to evaluate the effect of attenuation of MR coils on quantitative carotid PET/MR exams. Additionally, an automated attenuation correction method for flexible carotid MR coils was developed and evaluated. The attenuation of the carotid coil was measured by imaging a uniform water phantom injected with 37 MBq of 18F-FDG in a combined PET/MR scanner for 24 min with and without the coil. In the same session, an ultra-short echo time (UTE) image of the coil on top of the phantom was acquired. Using a combination of rigid and non-rigid registration, a CT-based attenuation map was registered to the UTE image of the coil for attenuation and scatter correction. After phantom validation, the effect of the carotid coil attenuation and the attenuation correction method were evaluated in five subjects. Phantom studies indicated that the overall loss of PET counts due to the coil was 6.3% with local region-of-interest (ROI) errors reaching up to 18.8%. Our registration method to correct for attenuation from the coil decreased the global error and local error (ROI) to 0.8% and 3.8%, respectively. The proposed registration method accurately captured the location and shape of the coil with a maximum spatial error of 2.6 mm. Quantitative analysis in human studies correlated with the phantom findings, but was dependent on the size of the ROI used in the analysis. MR coils result in significant error in PET quantification and thus attenuation correction is needed. The proposed strategy provides an operator-free method for attenuation and scatter correction for a flexible MRI carotid surface coil for routine clinical use.

  4. Local Multi-Channel RF Surface Coil versus Body RF Coil Transmission for Cardiac Magnetic Resonance at 3 Tesla: Which Configuration Is Winning the Game?

    PubMed Central

    Winter, Lukas; Dieringer, Matthias A.; Els, Antje; Oezerdem, Celal; Rieger, Jan; Kuehne, Andre; Cassara, Antonino M.; Pfeiffer, Harald; Wetterling, Friedrich; Niendorf, Thoralf

    2016-01-01

    Introduction The purpose of this study was to demonstrate the feasibility and efficiency of cardiac MR at 3 Tesla using local four-channel RF coil transmission and benchmark it against large volume body RF coil excitation. Methods Electromagnetic field simulations are conducted to detail RF power deposition, transmission field uniformity and efficiency for local and body RF coil transmission. For both excitation regimes transmission field maps are acquired in a human torso phantom. For each transmission regime flip angle distributions and blood-myocardium contrast are examined in a volunteer study of 12 subjects. The feasibility of the local transceiver RF coil array for cardiac chamber quantification at 3 Tesla is demonstrated. Results Our simulations and experiments demonstrate that cardiac MR at 3 Tesla using four-channel surface RF coil transmission is competitive versus current clinical CMR practice of large volume body RF coil transmission. The efficiency advantage of the 4TX/4RX setup facilitates shorter repetition times governed by local SAR limits versus body RF coil transmission at whole-body SAR limit. No statistically significant difference was found for cardiac chamber quantification derived with body RF coil versus four-channel surface RF coil transmission. Our simulation also show that the body RF coil exceeds local SAR limits by a factor of ~2 when driven at maximum applicable input power to reach the whole-body SAR limit. Conclusion Pursuing local surface RF coil arrays for transmission in cardiac MR is a conceptually appealing alternative to body RF coil transmission, especially for patients with implants. PMID:27598923

  5. Surface and gradiometer coils near a conducting body: the lift-off effect.

    PubMed

    Suits, B H; Garroway, A N; Miller, J B

    1998-12-01

    The use of surface coils in magnetic resonance is widespread. Examples include MRI, detection of subsurface aquifers by NMR, and, more recently, landmine detection by nuclear quadrupole resonance. In many of these cases a finite-sized sample to be examined is contained within a larger medium that is a poor electrical conductor, and eddy currents induced by the RF fields provide a loss mechanism that reduces the effective quality factor Q of the transmitter and receiver coils. Here the losses induced in a circular surface coil (a horizontal loop antenna) separated a distance from a dissipative medium are calculated and compared to measurements. It is shown that often the overall efficiency of the coil for magnetic resonance can be improved by displacing the coil away from the conducting medium a prescribed "lift-off" distance. The use of a gradiometer as a surface coil is also examined, and it is shown by theory and experiment that in certain circumstances such a gradiometer can be more efficient than a conventional surface coil for inspection of conducting media.

  6. VSGdb: a database for trypanosome variant surface glycoproteins, a large and diverse family of coiled coil proteins

    PubMed Central

    Marcello, Lucio; Menon, Suraj; Ward, Pauline; Wilkes, Jonathan M; Jones, Nicola G; Carrington, Mark; Barry, J David

    2007-01-01

    Background Trypanosomes are coated with a variant surface glycoprotein (VSG) that is so densely packed that it physically protects underlying proteins from effectors of the host immune system. Periodically cells expressing a distinct VSG arise in a population and thereby evade immunity. The main structural feature of VSGs are two long α-helices that form a coiled coil, and sets of relatively unstructured loops that are distal to the plasma membrane and contain most or all of the protective epitopes. The primary structure of different VSGs is highly variable, typically displaying only ~20% identity with each other. The genome has nearly 2000 VSG genes, which are located in subtelomeres. Only one VSG gene is expressed at a time, and switching between VSGs primarily involves gene conversion events. The archive of silent VSGs undergoes diversifying evolution rapidly, also involving gene conversion. The VSG family is a paradigm for α helical coiled coil structures, epitope variation and GPI-anchor signals. At the DNA level, the genes are a paradigm for diversifying evolutionary processes and for the role of subtelomeres and recombination mechanisms in generation of diversity in multigene families. To enable ready availability of VSG sequences for addressing these general questions, and trypanosome-specific questions, we have created VSGdb, a database of all known sequences. Description VSGdb contains fully annotated VSG sequences from the genome sequencing project, with which it shares all identifiers and annotation, and other available sequences. The database can be queried in various ways. Sequence retrieval, in FASTA format, can deliver protein or nucleotide sequence filtered by chromosomes or contigs, gene type (functional, pseudogene, etc.), domain and domain sequence family. Retrieved sequences can be stored as a temporary database for BLAST querying, reports from which include hyperlinks to the genome project database (GeneDB) CDS Info and to individual VSGdb

  7. Modulation of water surface waves with a coiling-up-space metasurface

    NASA Astrophysics Data System (ADS)

    Sun, H. T.; Wang, J. S.; Cheng, Y.; Wei, Q.; Liu, X. J.

    2016-05-01

    We have designed a gradient-index (GRIN) metasurface to modulate water surface waves (WSWs). The metasurface is composed of an array of coiling-up-space units with a deep sub-wavelength scale, and can focus/scatter WSWs when the units are arranged elaborately and pierced into water. The modulation of WSWs has been ascribed to the relative effective refractive GRIN of the coiling-up-space units, which can be tuned by changing the parameters such as the plate length of units. This work may have potential application in energy extraction of water wave.

  8. Multi circular-cavity surface coil for magnetic resonance imaging of monkey's brain at 4 Tesla

    NASA Astrophysics Data System (ADS)

    Osorio, A. I.; Solis-Najera, S. E.; Vázquez, F.; Wang, R. L.; Tomasi, D.; Rodriguez, A. O.

    2014-11-01

    Animal models in medical research has been used to study humans diseases for several decades. The use of different imaging techniques together with different animal models offers a great advantage due to the possibility to study some human pathologies without the necessity of chirurgical intervention. The employ of magnetic resonance imaging for the acquisition of anatomical and functional images is an excellent tool because its noninvasive nature. Dedicated coils to perform magnetic resonance imaging experiments are obligatory due to the improvement on the signal-to-noise ratio and reduced specific absorption ratio. A specifically designed surface coil for magnetic resonance imaging of monkey's brain is proposed based on the multi circular-slot coil. Numerical simulations of the magnetic and electric fields were also performed using the Finite Integration Method to solve Maxwell's equations for this particular coil design and, to study the behavior of various vector magnetic field configurations and specific absorption ratio. Monkey's brain images were then acquired with a research-dedicated magnetic resonance imaging system at 4T, to evaluate the anatomical images with conventional imaging sequences. This coil showed good quality images of a monkey's brain and full compatibility with standard pulse sequences implemented in research-dedicated imager.

  9. Segmented surface coil resonator for in vivo EPR applications at 1.1 GHz

    NASA Astrophysics Data System (ADS)

    Petryakov, Sergey; Samouilov, Alexandre; Chzhan-Roytenberg, Michael; Kesselring, Eric; Sun, Ziqi; Zweier, Jay L.

    2009-05-01

    A four-loop segmented surface coil resonator (SSCR) with electronic frequency and coupling adjustments was constructed with 18 mm aperture and loading capability suitable for in vivo Electron Paramagnetic Resonance (EPR) spectroscopy and imaging applications at L-band. Increased sample volume and loading capability were achieved by employing a multi-loop three-dimensional surface coil structure. Symmetrical design of the resonator with coupling to each loop resulted in high homogeneity of RF magnetic field. Parallel loops were coupled to the feeder cable via balancing circuitry containing varactor diodes for electronic coupling and tuning over a wide range of loading conditions. Manually adjusted high Q trimmer capacitors were used for initial tuning with subsequent tuning electronically controlled using varactor diodes. This design provides transparency and homogeneity of magnetic field modulation in the sample volume, while matching components are shielded to minimize interference with modulation and ambient RF fields. It can accommodate lossy samples up to 90% of its aperture with high homogeneity of RF and modulation magnetic fields and can function as a surface loop or a slice volume resonator. Along with an outer coaxial NMR surface coil, the SSCR enabled EPR/NMR co-imaging of paramagnetic probes in living rats to a depth of 20 mm.

  10. An improved hybrid MoM/FDTD technique for MRI RF coils modeling using Huygen's equivalent surface method.

    PubMed

    Li, Bing Keong; Liu, Feng; Weber, Ewald; Padhi, Shantanu; Crozier, Stuart

    2007-01-01

    In this work, an improved hybrid MoM/FDTD algorithm for modeling low to ultra high field MRI RF coil/sample interactions has been proposed. In our previous hybrid MoM/FDTD method, the accuracy of modeling MRI RF coils is generally hindered by two major issues, staircasing errors and rough approximation of the coil current distortions by electromagnetic reflections from sample. In view of this, a Huygen's equivalent surface method has been proposed to effectively bridge MoM and FDTD. In the improved hybrid MoM/FDTD algorithm, staircasing errors are eliminated, and most importantly the complex coil/tissue interactions are explicitly accounted for. The accuracy of the improved hybrid MoM/FDTD method is numerically verified with a well established hybrid Green function/MoM solution and also experimentally underpinned with MR images obtained using a prototype rotary phased array head coil.

  11. A combined solenoid-surface RF coil for high-resolution whole-brain rat imaging on a 3.0 Tesla clinical MR scanner.

    PubMed

    Underhill, Hunter R; Yuan, Chun; Hayes, Cecil E

    2010-09-01

    Rat brain models effectively simulate a multitude of human neurological disorders. Improvements in coil design have facilitated the wider utilization of rat brain models by enabling the utilization of clinical MR scanners for image acquisition. In this study, a novel coil design, subsequently referred to as the rat brain coil, is described that exploits and combines the strengths of both solenoids and surface coils into a simple, multichannel, receive-only coil dedicated to whole-brain rat imaging on a 3.0 T clinical MR scanner. Compared with a multiturn solenoid mouse body coil, a 3-cm surface coil, a modified Helmholtz coil, and a phased-array surface coil, the rat brain coil improved signal-to-noise ratio by approximately 72, 61, 78, and 242%, respectively. Effects of the rat brain coil on amplitudes of static field and radiofrequency field uniformity were similar to each of the other coils. In vivo, whole-brain images of an adult male rat were acquired with a T(2)-weighted spin-echo sequence using an isotropic acquisition resolution of 0.25 x 0.25 x 0.25 mm(3) in 60.6 min. Multiplanar images of the in vivo rat brain with identification of anatomic structures are presented. Improvement in signal-to-noise ratio afforded by the rat brain coil may broaden experiments that utilize clinical MR scanners for in vivo image acquisition.

  12. A new holder and surface MRI coil for the examination of the newborn infant hip.

    PubMed

    Krasny, R; Casser, H R; Requardt, H; Botschek, A

    1993-01-01

    A special holder was developed for examination of the infant hip joint using MRI. This holder allows the infant hip joint to be examined both in a neutral position and in various defined functional positions. A special integrated surface coil, also developed for this purpose, provides the high spatial resolution required for assessment of the fine joint structures. Thirty infants were examined and the new device has proved useful in advanced hip dysplasia, therapy-resistant subluxation and luxation, and for operative therapy planning (reconstruction of the acetabular roof, redirectional osteotomies). Interpretation errors due to misprojection can be eliminated to a large extent since the holder allows standardized and reproducible positioning.

  13. Proton spectral editing in the inhomogeneous radiofrequency field of a surface coil using modified stimulated echoes.

    PubMed

    Lahrech, H; Briguet, A

    1990-11-01

    It is shown that the modified stimulated echo sequence, [theta](+/- x +/- y)-t1-[theta](+ x)-t2/2-[2 theta](+ x)-t2/2- [theta](+ x)-t1-Acq(+/- x +/- y), denoted as MSTE[2 theta]x according to the exciter phase of the 2 theta pulse, is able to perform proton spectral editing without difference spectra. On the other hand, this sequence appears to be suitable for spatial localization. Sensitivity and spatial selectivity of MSTE and conventional stimulated echo sequence (STE) are briefly compared. MSTE is applied to editing lactate in the rat brain using the locally restricted excitation of a surface coil.

  14. Control and Calibration of a Staubli RX130 Robotic Arm for Construction of Surface Current Coils

    NASA Astrophysics Data System (ADS)

    Vanmeter, Patrick; Crawford, Christopher; Guler, Emre; Fugal, Mario; Irvin, Bradley

    2013-10-01

    Precision low energy neutron experiments require extremely uniform magnetic fields for manipulating the neutron spin. Such fields can be generated with surface current coils-precision 3-dimensional printed circuits. We are developing a facility to etch out these circuits on copper-plated curved forms using a high-speed spindle attached to the end-effector of a Staubli RX130 six-axis robotic arm. We describe our mathematical model of the robotic links and the software system we designed to control the motion of the arm and to prevent collisions during actuations. We developed a calibration procedure to achieve accuracy of 30 microns in the position of drill.

  15. Microtubule coils versus the surface membrane cytoskeleton in maintenance and restoration of platelet discoid shape.

    PubMed Central

    White, J. G.; Rao, G. H.

    1998-01-01

    The discoid form of blood platelets is important to their function in hemostasis. Recent studies have suggested that the spectrin-rich surface membrane cytoskeleton and the cytoplasmic, actin-rich cytoskeleton are responsible for discoid shape, shape change, and recovery after activation or chilling. Earlier studies had suggested that circumferential coils of microtubules supported the disc shape of resting platelets and that their repositioning or reassembly restored disc shape after exposure to low temperature. The present study has used the chilling-rewarming model, together with microtubule stabilizing (taxol) and disassembling (vincristine) agents to retest the relative importance of the surface membrane cytoskeleton and circumferential microtubules in platelet discoid shape and its restoration. Washed platelet samples were rested at 37 degrees C and chilled to 4 degrees C; chilled and rewarmed to 37 degrees C for 60 minutes; or chilled, rewarmed, and exposed to the same cycle in the presence or absence of vincristine or taxol and fixed for study by disseminated interference phase contrast microscopy and electron microscopy. Rhodamine-phalloidin and flow cytometry were used to measure changes in actin filament assembly. Chilling caused loss of disc shape, pseudopod extension, disassembly of microtubule coils, and assembly of new actin filaments. Rewarming resulted in restoration of disc shape, pseudopod retraction, disassembly of new actin filaments, and reassembly of circumferential microtubule coils. Vincristine converted discoid platelets to rounded cells that extended pseudopods when chilled and retracted them when rewarmed, leaving spheres that could undergo the same sequence of changes when chilled and rewarmed again. Taxol prevented cold-induced disassembly of microtubules and limited pseudopod formation. Rewarming caused retraction of pseudopods on taxol-treated, discoid cells. Cytochalasin B, an agent that blocks new actin filament assembly, alone or

  16. High-field 13C NMR spectroscopy of tissue in Vivo. A double-resonance surface-coil probe

    NASA Astrophysics Data System (ADS)

    Reo, Nicholas V.; Ewy, Coleen S.; Siegfried, Barry A.; Ackerman, Joseph J. H.

    A double-resonance surface-coil NMR probe is described for performance of high-field (8.5 T) proton decoupled carbon-13 experiments with tissue in vivo. The probe may be accommodated in standard, 89 mm i.d. clear bore, commercial spectrometers and is suitable for studies utilizing small laboratory animals such as mice, hamsters, and rats. A coaxial coil design is employed (10 mm diameter 13C coil, 20 mm diameter 1H coil) which provides ca. 40 dB attenuation between the 13C observe and 1H decouple channels. The inherent efficiency of the surface-coil configuration provides a sensitivity comparable to a commercial probe of the same nominal dimension (10 mm Helmholtz coil) and assures adequate decoupling in conductive samples with ca. 3-5 W power. In the absence of 13C isotopic enrichment, NMR spectra of rat leg, liver, and brain in vivo provide signalto-noise sufficient for 10 min time resolution. Administration of 100 mg of 90% 13C-labeled glucose into a peripheral vein of a ca. 300 g rat resulted in a liver glucose resonance which could be monitored with good signal-to-noise and 3 min time resolution.

  17. Coiling of viscous jets

    NASA Astrophysics Data System (ADS)

    Ribe, Neil M.

    2004-11-01

    A stream of viscous fluid falling from a sufficient height onto a surface forms a series of regular coils. I use a numerical model for a deformable fluid thread to predict the coiling frequency as a function of the thread's radius, the flow rate, the fall height, and the fluid viscosity. Three distinct modes of coiling can occur: viscous (e.g. toothpaste), gravitational (honey falling from a moderate height) and inertial (honey falling from a great height). When inertia is significant, three states of steady coiling with different frequencies can exist over a range of fall heights. The numerically predicted coiling frequencies agree well with experimental measurements in the inertial coiling regime.

  18. Electrically controllable twisted-coiled artificial muscle actuators using surface-modified polyester fibers

    NASA Astrophysics Data System (ADS)

    Park, Jungwoo; Yoo, Ji Wang; Seo, Hee Won; Lee, Youngkwan; Suhr, Jonghwan; Moon, Hyungpil; Koo, Ja Choon; Ryeol Choi, Hyouk; Hunt, Robert; Kim, Kwang Jin; Kim, Soo Hyun; Nam, Jae-Do

    2017-03-01

    As a new class of thermally activated actuators based on polymeric fibers, we investigated polyethylene terephthalate (PET) yarns for the development of a twisted-coiled polymer fiber actuator (TCA). The PET yarn TCA exhibited the maximum linear actuation up to 8.9% by external heating at above the glass transition temperature, 160 °C–180 °C. The payload of the actuator was successfully correlated with the preload and training-load conditions by an empirical equation. Furthermore, the PET-based TCA was electrically driven by Joule heating after the PET surface was metallization with silver. For the fast and precise control of PET yarn TCA, electroless silver plating was conducted to form electrical conductive layers on the PET fiber surface. The silver plated PET-based TCA was tested by Joule heating and the tensile actuation was increased up to 12.1% (6 V) due to the enhanced surface hardness and slippage of PET fibers. Overall, silver plating of the polymeric yarn provided a fast actuation speed and enhanced actuation performance of the TCA actuator by Joule heating, providing a great potential for being used in artificial muscle for biomimetic machines including robots, industrial actuators and powered exoskeletons.

  19. RF surface receive array coils: the art of an LC circuit.

    PubMed

    Fujita, Hiroyuki; Zheng, Tsinghua; Yang, Xiaoyu; Finnerty, Matthew J; Handa, Shinya

    2013-07-01

    The radiofrequency (RF) receive array coil is a complicated device with many inductors and capacitors and serves as one of the most critical magnetic resonance imaging (MRI) electronic devices. It directly determines the achievable level of signal-to-noise ratio (SNR). Simply put, however, the RF coil is nothing but an LC circuit. The receive array coil was first proposed more than 20 years ago, evolving from a simple arrangement with a few electronic channels to a complicated system of 128 channels, enabling highly sophisticated parallel imaging, at different field strengths. This article summarizes the basic concepts pertaining to RF receive coil arrays and their associated SNR and reviews the theories behind the major components of such arrays. This includes discussions of the intrinsic SNR of a receive coil, the matching circuits, low-noise preamplifiers, coupling/decoupling amongst coils, the coupling between receive and transmit coils, decoupling via preamplifiers, and baluns. An 8-channel receive array coil on a cylindrical former serves as a useful example for demonstrating various points in the review.

  20. Configuration of a polymer chain in bulk and close to surfaces near the coil-to-globule transition

    NASA Astrophysics Data System (ADS)

    Rissanou, Anastassia N.; Bitsanis, Ioannis A.; Anastasiadis, Spiros H.

    2003-03-01

    The coil to globule transition of polymer chains in bulk solution or attached onto a surface is investigated using Monte Carlo simulations on a cubic lattice as a function of MW, solvent quality and interfacial energy. Monte Carlo results for an isolated chain in bulk solution show an anomalous dependence of RG on the MW as the solvent becomes poorer: it exhibits a N-independent regime for intermediate MWs where there is a qualitative change in the form of the density distribution in the inner part of the chain. The coil to globule transition is in accord with Khokhlov's theoretical predictions. The coupling between the coil to globule transition and the adsorption of the chain onto attractive surfaces is investigated as a function of the surface energy. The adsorbed chain in poor solvent tends to a pancake-like conformation for very attractive surfaces. The whole behavior is not controlled by the bulk Θ temperature but by a new temperature Θ^', which depends strongly on the surface energy and tends to the value of the Θ temperature in two-dimensions.

  1. High-Resolution MR Imaging with Strong Local "surface" Gradient Coils, and, Optimization of Spgr Techniques for Functional MR Imaging.

    NASA Astrophysics Data System (ADS)

    Jin, Haoran

    In this thesis we discuss two specific topics in magnetic resonance imaging. The first concerns the technical requirements of high resolution MR imaging. Unique local "surface" gradient coils have been designed, constructed, integrated with a whole body MR imaging system, and used to acquire MR images demonstrating higher spatial resolution in three dimensions. The novel gradient coil design generates a strong linear gradient-field in three dimensions near the planar surface of the coil assembly for high resolution MR skin imaging. The rise times of the gradient coils were measured to be less than 250 mus, allowing rapid gradient coil switching. No significant eddy current effects have been found on the images. Images of a phantom and human skin with a field of view 3 cm by 3 cm and matrix size of 512 x 384 were obtained, corresponding to an in-plane resolution of 58 by 78 mu m. The resulting images represent a significant improvement in limiting spatial resolution compared to conventional MR images. The second topic of this thesis is functional MR imaging (FMRI). Functional MR imaging is based on the concept that neural activity in the cerebral cortex causes an increase in blood flow and a decrease in capillary deoxyhemoglobin concentrations, producing a signal enhancement in T2 ^*-weighted pulse sequences. The magnetic susceptibility of blood changes the oxygenation, changing the local T2^*. Spoiled gradient echo (SPGR) techniques both theoretically and experimentally have been optimized for functional MRI of human motor cortex. Experimental measurements have been performed and compared with the theoretical optimizations of signal to noise ratios of subtracted SPGR imaging. The experimental data are in good agreement with theoretical calculations. An FMRI of motor cortex stimulation with more than 5% intensity change has been observed using optimized techniques. Post imaging processing has been employed for displaying signal changes in the functional MR imaging.

  2. NCSX Trim Coil Design

    SciTech Connect

    M. Kalish, A. Brooks, J. Rushinski, R. Upcavage

    2009-05-29

    The National Compact Stellarator Experiment (NCSX) was being constructed at the Princeton Plasma Physics Laboratory in partnership with Oak Ridge National Laboratory before work was stopped in 2008. The objective of this experiment was to develop the stellarator concept and evaluate it's potential as a model for future fusion power plants. Stellarator design requires very precisely positioned Modular Coils of complex shape to form 3D plasmas. In the design of NCSX, Trim Coils were required to compensate for both the positioning of the coils during assembly and the fabrication tolerances of the Modular Coils. Use of the Trim Coils allowed for larger tolerances increasing ease of assembly and decreasing overall cost. A set of Trim coils was developed to suppress the toroidal flux in island regions due to misalignment, magnetic materials, and eddy currents. The requirement imposed upon the design forced the toroidal flux in island regions below 10% of the total toroidal flux in the plasma. An analysis was first performed to evaluate candidate Trim Coil configurations iterating both the size, number, and position of the coils. The design was optimized considering both performance and cost while staying within the tight restraints presented by the space limited geometry. The final design of the Trim Coils incorporated a 48 Coil top bottom symmetric set. Fabrication costs were minimized by having only two coil types and using a planar conventional design with off the shelf commercial conductor. The Trim Coil design incorporated supports made from simple structural shapes assembled together in a way which allowed for adjustment as well as accommodation for the tolerance build up on the mating surfaces. This paper will summarize the analysis that led to the optimization of the Trim Coils set, the trim coil mechanical design, thermal and stress analysis, and the design of the supporting Trim Coil structure.

  3. SU-E-J-239: Influence of RF Coil Materials On Surface and Buildup Dose From a 6MV Photon Beam

    SciTech Connect

    Ghila, A; Fallone, B; Rathee, S

    2015-06-15

    Purpose: In order to perform real time tumour tracking using an integrated Linac-MR, images have to be acquired during irradiation. MRI uses RF coils in close proximity to the imaged volume. Given current RF coil designs this means that the high energy photons will be passing through the coil before reaching the patient. This study experimentally investigates the dose modifications that occur due to the presence of various RF coil materials in the treatment beam. Methods: Polycarbonate, copper or aluminum tape, and Teflon were used to emulate the base, conductor and cover respectively of a surface RF coil. These materials were placed at various distances from the surface of polystyrene or solid water phantoms which were irradiated in the presence of no magnetic field, a transverse 0.2T magnetic field, and a parallel 0.2T magnetic field. Percent depth doses were measured using ion chambers. Results: A significant increase in surface and buildup dose is observed. The surface dose is seen to decrease with an increasing separation between the emulated coil and the phantom surface, when no magnetic field is present. When a transverse magnetic field is applied the surface dose decreases faster with increasing separation, as some of the electrons created in the coil are curved away from the phantom’s surface. When a parallel field is present the surface dose stays approximately constant for small separations, only slightly decreasing for separations greater than 5cm, since the magnetic field focuses the electrons produced in the coil materials not allowing them to scatter. Conclusion: Irradiating a patient through an RF coil leads to an increase in the surface and buildup doses. Mitigating this increase is important for the successful clinical use of either a transverse or a parallel configuration Linac-MR unit. This project is partially supported by an operating grant from the Canadian Institute of Health Research (CIHR MOP 93752)

  4. Thin film MRI-high resolution depth imaging with a local surface coil and spin echo SPI.

    PubMed

    Ouriadov, Alexei V; MacGregor, Rodney P; Balcom, Bruce J

    2004-07-01

    A multiple echo, single point imaging technique, employing a local surface coil probe, is presented for examination of thin film samples. Depth images with a nominal resolution of 5 microm were acquired with acquisition times on the order of 10 min. The method may be used to observe dynamic phenomenon such as polymerization, wetting, and drying in thin film samples. It is readily adapted to spatially resolved diffusion coefficient and T2 relaxation time mapping.

  5. The neuronal Kv4 channel complex.

    PubMed

    Covarrubias, Manuel; Bhattacharji, Aditya; De Santiago-Castillo, Jose A; Dougherty, Kevin; Kaulin, Yuri A; Na-Phuket, Thanawath Ratanadilok; Wang, Guangyu

    2008-08-01

    Kv4 channel complexes mediate the neuronal somatodendritic A-type K(+) current (I(SA)), which plays pivotal roles in dendritic signal integration. These complexes are composed of pore-forming voltage-gated alpha-subunits (Shal/Kv4) and at least two classes of auxiliary beta-subunits: KChIPs (K(+)-Channel-Interacting-Proteins) and DPLPs (Dipeptidyl-Peptidase-Like-Proteins). Here, we review our investigations of Kv4 gating mechanisms and functional remodeling by specific auxiliary beta-subunits. Namely, we have concluded that: (1) the Kv4 channel complex employs novel alternative mechanisms of closed-state inactivation; (2) the intracellular Zn(2+) site in the T1 domain undergoes a conformational change tightly coupled to voltage-dependent gating and is targeted by nitrosative modulation; and (3) discrete and specific interactions mediate the effects of KChIPs and DPLPs on activation, inactivation and permeation of Kv4 channels. These studies are shedding new light on the molecular bases of I(SA) function and regulation.

  6. Removing Signal Intensity Inhomogeneity From Surface Coil MRI Using Discrete Wavelet Transform and Wavelet Packet

    DTIC Science & Technology

    2001-10-25

    We evaluate a combined discrete wavelet transform (DWT) and wavelet packet algorithm to improve the homogeneity of magnetic resonance imaging when a...image and uses this information to normalize the image intensity variations. Estimation of the coil sensitivity profile based on the wavelet transform of

  7. Simplified correction of B1 inhomogeneity for chemical exchange saturation transfer (CEST) MRI measurement with surface transceiver coil

    NASA Astrophysics Data System (ADS)

    Sun, Phillip Z.; Zhou, Iris Y.; Igarashi, Takahiro; Guo, Yingkun; Xiao, Gang; Wu, Renhua

    2015-03-01

    Chemical exchange saturation transfer (CEST) MRI is sensitive to dilute exchangeable protons and local properties such as pH and temperate, yet its susceptibility to field inhomogeneity limits its in vivo applications. Particularly, CEST measurement varies with RF irradiation power, the dependence of which is complex due to concomitant direct RF saturation (RF spillover) effect. Because the volume transmitters provide relatively homogeneous RF field, they have been conventionally used for CEST imaging despite of their elevated specific absorption rate (SAR) and relatively low sensitivity than surface coils. To address this limitation, we developed an efficient B1 inhomogeneity correction algorithm that enables CEST MRI using surface transceiver coils. This is built on recent work that showed the inverse CEST asymmetry analysis (CESTRind) is not susceptible to confounding RF spillover effect. We here postulated that the linear relationship between RF power level and CESTRind can be extended for correcting B1 inhomogeneity induced CEST MRI artifacts. Briefly, we prepared a tissue-like Creatine gel pH phantom and collected multiparametric MRI including relaxation, field map and CEST MRI under multiple RF power levels, using a conventional surface transceiver coil. The raw CEST images showed substantial heterogeneity due to B1 inhomogeneity, with pH contrast to noise ratio (CNR) being 8.8. In comparison, pH MRI CNR of the fieldinhomogeneity corrected CEST MRI was found to be 17.2, substantially higher than that without correction. To summarize, our study validated an efficient field inhomogeneity correction that enables sensitive CEST MRI with surface transceiver, promising for in vivo translation.

  8. Surface segregation of fluorinated moieties on random copolymer films controlled by random-coil conformation of polymer chains in solution.

    PubMed

    Xue, Dongwu; Wang, Xinping; Ni, Huagang; Zhang, Wei; Xue, Gi

    2009-02-17

    The relationship between solution properties, film-forming methods, and the solid surface structures of random copolymers composed of butyl methacrylate and dodecafluorheptyl methylacrylate (DFHMA) was investigated by contact angle measurements, X-ray photoelectron spectroscopy, sum frequency generation vibrational spectroscopy, and surface tension measurements. The results, based on thermodynamic considerations, demonstrated that the random copolymer chain conformation at the solution/air interface greatly affected the surface structure of the resulting film, thereby determining the surface segregation of fluorinated moieties on films obtained by various film-forming techniques. When the fluorinated monomer content of the copolymer solution was low, entropic forces dominated the interfacial structure, with the perfluoroalkyl groups unable to migrate to the solution/air interface and thus becoming buried in a random-coil chain conformation. When employing this copolymer solution for film preparation by spin-coating, the copolymer chains in solution were likely extended due to centrifugal forces, thereby weakening the entropy effect of the polymer chains. Consequently, this resulted in the segregation of the fluorinated moieties on the film surface. For the films prepared by casting, the perfluoroalkyl groups were, similar to those in solution, incapable of segregating at the film surface and were thus buried in the random-coil chains. When the copolymers contained a high content of DFHMA, the migration of perfluoroalkyl groups at the solution/air interface was controlled by enthalpic forces, and the perfluoroalkyl groups segregated at the surface of the film regardless of the film-forming technique. The aim of the present work was to obtain an enhanced understanding of the formation mechanism of the chemical structure on the surface of the polymer film, while demonstrating that film-forming methods may be used in practice to promote the segregation of fluorinated

  9. Aneurysm permeability following coil embolization: packing density and coil distribution

    PubMed Central

    Chueh, Ju-Yu; Vedantham, Srinivasan; Wakhloo, Ajay K; Carniato, Sarena L; Puri, Ajit S; Bzura, Conrad; Coffin, Spencer; Bogdanov, Alexei A; Gounis, Matthew J

    2015-01-01

    Background Rates of durable aneurysm occlusion following coil embolization vary widely, and a better understanding of coil mass mechanics is desired. The goal of this study is to evaluate the impact of packing density and coil uniformity on aneurysm permeability. Methods Aneurysm models were coiled using either Guglielmi detachable coils or Target coils. The permeability was assessed by taking the ratio of microspheres passing through the coil mass to those in the working fluid. Aneurysms containing coil masses were sectioned for image analysis to determine surface area fraction and coil uniformity. Results All aneurysms were coiled to a packing density of at least 27%. Packing density, surface area fraction of the dome and neck, and uniformity of the dome were significantly correlated (p<0.05). Hence, multivariate principal components-based partial least squares regression models were used to predict permeability. Similar loading vectors were obtained for packing and uniformity measures. Coil mass permeability was modeled better with the inclusion of packing and uniformity measures of the dome (r2=0.73) than with packing density alone (r2=0.45). The analysis indicates the importance of including a uniformity measure for coil distribution in the dome along with packing measures. Conclusions A densely packed aneurysm with a high degree of coil mass uniformity will reduce permeability. PMID:25031179

  10. Coil bobbin for stable superconducting coils

    SciTech Connect

    Kashima, T.; Yamanaka, A.; Nishijima, S.; Okada, T.

    1996-12-31

    The coil bobbin for a.c. coils have been prepared with the high strength polyethylene fiber (DF) reinforced plastics (DFRP) or with hybrid composites reinforced by DF and glass fiber (GF). The coils with the bobbin were found to be markedly stable. The DF has a large negative thermal expansion coefficient and hence the circumferential thermal strain of bobbin can be designed by changing the ratio of DF to GF layer thickness (DF/GF). It was found that the thermal expansion coefficient in the circumferential direction of the outer surface changed from negative to positive with increasing DF/GF and became nearly zero at a DF/GF of approximately 5.1 kA rms class a.c. coils having a bobbin with a negative thermal expansion coefficient or small thermal contraction in the circumferential direction were fabricated and were confirmed to show higher quench current than that with a GFRP bobbin.

  11. The TRPM4 channel inhibitor 9-phenanthrol

    PubMed Central

    Guinamard, R; Hof, T; Del Negro, C A

    2014-01-01

    The phenanthrene-derivative 9-phenanthrol is a recently identified inhibitor of the transient receptor potential melastatin (TRPM) 4 channel, a Ca2+-activated non-selective cation channel whose mechanism of action remains to be determined. Subsequent studies performed on other ion channels confirm the specificity of the drug for TRPM4. In addition, 9-phenanthrol modulates a variety of physiological processes through TRPM4 current inhibition and thus exerts beneficial effects in several pathological conditions. 9-Phenanthrol modulates smooth muscle contraction in bladder and cerebral arteries, affects spontaneous activity in neurons and in the heart, and reduces lipopolysaccharide-induced cell death. Among promising potential applications, 9-phenanthrol exerts cardioprotective effects against ischaemia-reperfusion injuries and reduces ischaemic stroke injuries. In addition to reviewing the biophysical effects of 9-phenanthrol, here we present information about its appropriate use in physiological studies and possible clinical applications. PMID:24433510

  12. Practical design of a 4 Tesla double-tuned RF surface coil for interleaved 1H and 23Na MRI of rat brain

    NASA Astrophysics Data System (ADS)

    Alecci, M.; Romanzetti, S.; Kaffanke, J.; Celik, A.; Wegener, H. P.; Shah, N. J.

    2006-08-01

    MRI is proving to be a very useful tool for sodium quantification in animal models of stroke, ischemia, and cancer. In this work, we present the practical design of a dual-frequency RF surface coil that provides 1H and 23Na images of the rat head at 4 T. The dual-frequency RF surface coil comprised of a large loop tuned to the 1H frequency and a smaller co-planar loop tuned to the 23Na frequency. The mutual coupling between the two loops was eliminated by the use of a trap circuit inserted in the smaller coil. This independent-loop design was versatile since it enabled a separate optimisation of the sensitivity and RF field distributions of the two coils. To allow for an easy extension of this simple double-tuned coil design to other frequencies (nuclei) and dimensions, we describe in detail the practical aspects of the workbench design and MRI testing using a phantom that mimics in vivo conditions. A comparison between our independent-loop, double-tuned coil and a single-tuned 23Na coil of equal size obtained with a phantom matching in vivo conditions, showed a reduction of the 23Na sensitivity (about 28 %) because of signal losses in the trap inductance. Typical congruent 1H and 23Na rat brain images showing good SNR ( 23Na: brain 7, ventricular cerebrospinal fluid 11) and spatial resolution ( 23Na: 1.25 × 1.25 × 5 mm 3) are also reported. The in vivo SNR values obtained with this coil were comparable to, if not better than, other contemporary designs in the literature.

  13. ELECTRICAL COIL STRUCTURE

    DOEpatents

    Baker, W.R.; Hartwig, A.

    1962-09-25

    A compactly wound electrical coil is designed for carrying intense pulsed currents such as are characteristic of controlled thermonuclear reaction devices. A flat strip of conductor is tightly wound in a spiral with a matching flat strip of insulator. To provide for a high fluid coolant flow through the coil with minimum pumping pressure, a surface of the conductor is scored with parallel transverse grooves which form short longitudinal coolant pasaages when the conductor is wound in the spiral configuration. Owing to this construction, the coil is extremely resistant to thermal and magnetic shock from sudden high currents. (AEC)

  14. Commercial applications for COIL

    NASA Astrophysics Data System (ADS)

    Solomon, Wayne C.; Carroll, David L.; King, D. M.; Fockler, L. A.; Stromberg, D. S.; Sexauer, M.; Milmoe, A.; Sentman, Lee H.

    2000-01-01

    The chemical oxygen-iodine laser (COIL) is a high power, fiber deliverable tool, which can be used for a number of different industrial applications. COIL is of particular interest because of its short fiber deliverable wavelength, high scaleable continuous wave power, and excellent material interaction properties. In past research the University of Illinois at Urbana-Champaign identified and decommissioning and decontamination (DD) of nuclear facilities as a primary focus for COIL technology. DD will be a major challenge in the coming decades. The use of a robotically driven fiber delivered cutting/ablation tool in contaminated areas promises to lower risks to workers for the DD mission. Further, the high cutting speed of COIL will significantly reduce the time required to cut contaminated equipment, reducing costs. The high power of COIL will permit the dismantling of thick stacks of piping and equipment as well as reactor vessels. COIL is very promising for the removal of material from contaminated surfaces, perhaps to depths thicker than an inch. Laser cutting and ablation minimizes dust and fumes, which reduces the required number of high efficiency particulate accumulator filters, thus reducing costly waste disposal. Other potential industrial applications for COIL are shipbuilding, automotive manufacturing, heavy machinery manufacturing, tasks requiring underwater cutting or welding, and there appear to be very promising applications for high powers lasers in the oil industry.

  15. Enhancing Induction Coil Reliability

    NASA Astrophysics Data System (ADS)

    Kreter, K.; Goldstein, R.; Yakey, C.; Nemkov, V.

    2014-12-01

    In induction hardening, thermal fatigue is one of the main copper failure modes of induction heat treating coils. There have been papers published that describe this failure mode and others that describe some good design practices. The variables previously identified as the sources of thermal fatigue include radiation from the part surface, frequency, current, concentrator losses, water pressure and coil wall thickness. However, there is very little quantitative data on the factors that influence thermal fatigue in induction coils is available in the public domain. By using finite element analysis software this study analyzes the effect of common design variables of inductor cooling, and quantifies the relative importance of these variables. A comprehensive case study for a single shot induction coil with Fluxtrol A concentrator applied is used for the analysis.

  16. CAMAC based 4-channel 12-bit digitizer

    NASA Astrophysics Data System (ADS)

    Srivastava, Amit K.; Sharma, Atish; Raval, Tushar; Reddy, D. Chenna

    2010-02-01

    With the development in Fusion research a large number of diagnostics are being used to understand the complex behaviour of plasma. During discharge, several diagnostics demand high sampling rate and high bit resolution to acquire data for rapid changes in plasma parameters. For the requirements of such fast diagnostics, a 4-channel simultaneous sampling, high-speed, 12-bit CAMAC digitizer has been designed and developed which has several important features for application in CAMAC based nuclear instrumentation. The module has independent ADC per channel for simultaneous sampling and digitization, and 512 Ksamples RAM per channel for on-board storage. The digitizer has been designed for event based acquisition and the acquisition window gives post-trigger as well as pre-trigger (software selectable) data that is useful for analysis. It is a transient digitizer and can be operated either in pre/post trigger mode or in burst mode. The record mode and the active memory size are selected through software commands to satisfy the current application. The module can be used to acquire data at high sampling rate for short time discharge e.g. 512 ms at 1MSPS. The module can also be used for long time discharge at low sampling rate e.g. 512 seconds at 1KSPS. This paper describes the design of digitizer module, development of VHDL code for hardware logic, Graphical User Interface (GUI) and important features of module from application point of view. The digitizer has CPLD based hardware logic, which provides flexibility in configuring the module for different sampling rates and different pre/post trigger samples through GUI. The digitizer can be operated with either internal (for testing/acquisition) or external (synchronized acquisition) clock and trigger. The digitizer has differential inputs with bipolar input range ±5V and it is being used with sampling rate of 1 MSamples Per Second (MSPS) per channel but it also supports higher sampling rate up to 3MSPS per channel. A

  17. Dysregulation of Kv3.4 channels in dorsal root ganglia following spinal cord injury.

    PubMed

    Ritter, David M; Zemel, Benjamin M; Hala, Tamara J; O'Leary, Michael E; Lepore, Angelo C; Covarrubias, Manuel

    2015-01-21

    Spinal cord injury (SCI) patients develop chronic pain involving poorly understood central and peripheral mechanisms. Because dysregulation of the voltage-gated Kv3.4 channel has been implicated in the hyperexcitable state of dorsal root ganglion (DRG) neurons following direct injury of sensory nerves, we asked whether such a dysregulation also plays a role in SCI. Kv3.4 channels are expressed in DRG neurons, where they help regulate action potential (AP) repolarization in a manner that depends on the modulation of inactivation by protein kinase C (PKC)-dependent phosphorylation of the channel's inactivation domain. Here, we report that, 2 weeks after cervical hemicontusion SCI, injured rats exhibit contralateral hypersensitivity to stimuli accompanied by accentuated repetitive spiking in putative DRG nociceptors. Also in these neurons at 1 week after laminectomy and SCI, Kv3.4 channel inactivation is impaired compared with naive nonsurgical controls. At 2-6 weeks after laminectomy, however, Kv3.4 channel inactivation returns to naive levels. Conversely, Kv3.4 currents at 2-6 weeks post-SCI are downregulated and remain slow-inactivating. Immunohistochemistry indicated that downregulation mainly resulted from decreased surface expression of the Kv3.4 channel, as whole-DRG-protein and single-cell mRNA transcript levels did not change. Furthermore, consistent with Kv3.4 channel dysregulation, PKC activation failed to shorten the AP duration of small-diameter DRG neurons. Finally, re-expressing synthetic Kv3.4 currents under dynamic clamp conditions dampened repetitive spiking in the neurons from SCI rats. These results suggest a novel peripheral mechanism of post-SCI pain sensitization implicating Kv3.4 channel dysregulation and potential Kv3.4-based therapeutic interventions.

  18. Dysregulation of Kv3.4 Channels in Dorsal Root Ganglia Following Spinal Cord Injury

    PubMed Central

    Ritter, David M.; Zemel, Benjamin M.; Hala, Tamara J.; O'Leary, Michael E.; Lepore, Angelo C.

    2015-01-01

    Spinal cord injury (SCI) patients develop chronic pain involving poorly understood central and peripheral mechanisms. Because dysregulation of the voltage-gated Kv3.4 channel has been implicated in the hyperexcitable state of dorsal root ganglion (DRG) neurons following direct injury of sensory nerves, we asked whether such a dysregulation also plays a role in SCI. Kv3.4 channels are expressed in DRG neurons, where they help regulate action potential (AP) repolarization in a manner that depends on the modulation of inactivation by protein kinase C (PKC)-dependent phosphorylation of the channel's inactivation domain. Here, we report that, 2 weeks after cervical hemicontusion SCI, injured rats exhibit contralateral hypersensitivity to stimuli accompanied by accentuated repetitive spiking in putative DRG nociceptors. Also in these neurons at 1 week after laminectomy and SCI, Kv3.4 channel inactivation is impaired compared with naive nonsurgical controls. At 2–6 weeks after laminectomy, however, Kv3.4 channel inactivation returns to naive levels. Conversely, Kv3.4 currents at 2–6 weeks post-SCI are downregulated and remain slow-inactivating. Immunohistochemistry indicated that downregulation mainly resulted from decreased surface expression of the Kv3.4 channel, as whole-DRG-protein and single-cell mRNA transcript levels did not change. Furthermore, consistent with Kv3.4 channel dysregulation, PKC activation failed to shorten the AP duration of small-diameter DRG neurons. Finally, re-expressing synthetic Kv3.4 currents under dynamic clamp conditions dampened repetitive spiking in the neurons from SCI rats. These results suggest a novel peripheral mechanism of post-SCI pain sensitization implicating Kv3.4 channel dysregulation and potential Kv3.4-based therapeutic interventions. PMID:25609640

  19. Two-exponential analysis of spin-spin proton relaxation times in MR imaging using surface coils

    SciTech Connect

    Schad, L.R.; Brix, G.; Semmler, W.; Gueckel, F.L.; Lorenz, W.J. )

    1989-07-01

    Proton relaxation time measurements were performed on a standard whole body MR imager operating at 1.5 T using a conventional surface coil of the manufacturer. A combined CP/CPMG multiecho, multislice sequence was used for the T1 and T2 relaxation time measurements. Two repetition times of 2000 ms (30 echoes) and 600 ms (2 echoes) with 180 degrees-pulse intervals of 2 tau = 22 ms were interleaved in this sequence. A two-exponential T2 analysis of each pixel of the spin-echo images was computed in a case of an acoustic neurinoma. The two-exponential images show a short component (T2S) due to white and gray matter and a long component (T2S) due to the cerebrospinal fluid. In the fatty tissue two components with T2S = 35 {plus minus} 3 ms and T2L = 164 {plus minus} 7 ms were measured. Comparing with Gd-DTPA imaging the relaxation time images show a clear differentiation of vital tumor tissue and cerebrospinal fluid.

  20. Pulse Coil Tester

    NASA Technical Reports Server (NTRS)

    Simon, Richard A.

    1988-01-01

    Set of relays tested easily and repeatedly. Pulse coil tester causes coil under test to generate transient voltage; waveform indicates condition of coil. Tester accommodates assembly of up to four coils at a time.

  1. Rotor assembly including superconducting magnetic coil

    DOEpatents

    Snitchler, Gregory L.; Gamble, Bruce B.; Voccio, John P.

    2003-01-01

    Superconducting coils and methods of manufacture include a superconductor tape wound concentrically about and disposed along an axis of the coil to define an opening having a dimension which gradually decreases, in the direction along the axis, from a first end to a second end of the coil. Each turn of the superconductor tape has a broad surface maintained substantially parallel to the axis of the coil.

  2. Coiled tubing - Operations and services

    SciTech Connect

    Gronseth, J.M. )

    1993-04-01

    Drilling with a continuous (rather than jointed) drill string is an old concept that is gaining new attention as a result of recent advances made in coiled tubing and drilling technology. The development of larger diameter, reliable, high-strength coiled tubing and smaller diameter, positive displacement motors, orienting tools, surveying systems and fixed cutting drill bits have given drilling with a continuous drill string a capability that was previously unattainable. Like its many other uses, (e.g., squeeze cementing, wellbore cleanouts, flow initiation, logging) the continuity of coiled tubing gives it several advantages over conventional drill strings. These include: drilling underbalanced safely, significantly reduced trip time, continuous circulation, smaller surface requirements. Coiled tubing drilling operations have smaller surface lease requirements than most conventional rigs due to the smaller footprint of the coiled tubing unit and associated equipment. Current coiled tubing drilling operations have the following limitations: conventional rig assistance is required for well preparation; conventional rigs must assist in running long protective and production casing strings or liners; hole sizes are smaller; working depth capabilities are shallower, coiled tubing life is less. This paper goes on to discuss the history of continuous drill strings and includes information on tubing units, circulating systems, drilling fluids, well control systems, downhole tools, orientation tools, and bottomhole assemblies. It then gives a cost comparison and an application of this type of drilling.

  3. The TRPM4 channel is functionally important for the beneficial cardiac remodeling induced by endurance training.

    PubMed

    Gueffier, Mélanie; Zintz, Justin; Lambert, Karen; Finan, Amanda; Aimond, Franck; Chakouri, Nourdine; Hédon, Christophe; Granier, Mathieu; Launay, Pierre; Thireau, Jérôme; Richard, Sylvain; Demion, Marie

    2017-02-21

    Cardiac hypertrophy (CH) is an adaptive process that exists in two distinct forms and allows the heart to adequately respond to an organism's needs. The first form of CH is physiological, adaptive and reversible. The second is pathological, irreversible and associated with fibrosis and cardiomyocyte death. CH involves multiple molecular mechanisms that are still not completely defined but it is now accepted that physiological CH is associated more with the PI3-K/Akt pathway while the main signaling cascade activated in pathological CH involves the Calcineurin-NFAT pathway. It was recently demonstrated that the TRPM4 channel may act as a negative regulator of pathological CH by regulating calcium entry and thus the Cn-NFAT pathway. In this study, we examined if the TRPM4 channel is involved in the physiological CH process. We evaluated the effects of 4 weeks endurance training on the hearts of Trpm4 (+/+) and Trpm4 (-/-) mice. We identified an elevated functional expression of the TRPM4 channel in cardiomyocytes after endurance training suggesting a potential role for the channel in physiological CH. We then observed that Trpm4 (+/+) mice displayed left ventricular hypertrophy after endurance training associated with enhanced cardiac function. By contrast, Trpm4 (-/-) mice did not develop these adaptions. While Trpm4 (-/-) mice did not develop gross cardiac hypertrophy, the cardiomyocyte surface area was larger and associated with an increase of Tunel positive cells. Endurance training in Trpm4 (+/+) mice did not increase DNA fragmentation in the heart. Endurance training in Trpm4 (+/+) mice was associated with activation of the classical physiological CH Akt pathway while Trpm4 (-/-) favored the Calcineurin pathway. Calcium studies demonstrated that TRPM4 channel negatively regulates calcium entry providing support for activation of the Cn-NFAT pathway in Trpm4 (-/-) mice. In conclusion, we provide evidence for the functional expression of TRPM4 channel in response

  4. Coiled-Coil Design: Updated and Upgraded.

    PubMed

    Woolfson, Derek N

    2017-01-01

    α-Helical coiled coils are ubiquitous protein-folding and protein-interaction domains in which two or more α-helical chains come together to form bundles. Through a combination of bioinformatics analysis of many thousands of natural coiled-coil sequences and structures, plus empirical protein engineering and design studies, there is now a deep understanding of the sequence-to-structure relationships for this class of protein architecture. This has led to considerable success in rational design and what might be termed in biro de novo design of simple coiled coils, which include homo- and hetero-meric parallel dimers, trimers and tetramers. In turn, these provide a toolkit for directing the assembly of both natural proteins and more complex designs in protein engineering, materials science and synthetic biology. Moving on, the increased and improved use of computational design is allowing access to coiled-coil structures that are rare or even not observed in nature, for example α-helical barrels, which comprise five or more α-helices and have central channels into which different functions may be ported. This chapter reviews all of these advances, outlining improvements in our knowledge of the fundamentals of coiled-coil folding and assembly, and highlighting new coiled coil-based materials and applications that this new understanding is opening up. Despite considerable progress, however, challenges remain in coiled-coil design, and the next decade promises to be as productive and exciting as the last.

  5. 4. CHANNEL DIMENSIONS AND ALIGNMENT RESEARCH INSTRUMENTATION. VIDEOCONTROLED MODEL BOAT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. CHANNEL DIMENSIONS AND ALIGNMENT RESEARCH INSTRUMENTATION. VIDEO-CONTROLED MODEL BOAT AT FAR END OF MODEL NAVIGATION CHANNEL, HEADING INTO SHELTER AND TOWARD CONTROL TRAILER. - Waterways Experiment Station, Hydraulics Laboratory, Halls Ferry Road, 2 miles south of I-20, Vicksburg, Warren County, MS

  6. Bisandrographolide from Andrographis paniculata activates TRPV4 channels.

    PubMed

    Smith, Paula L; Maloney, Katherine N; Pothen, Randy G; Clardy, Jon; Clapham, David E

    2006-10-06

    Many transient receptor potential (TRP) channels are activated or blocked by various compounds found in plants; two prominent examples include the activation of TRPV1 channels by capsaicin and the activation of TRPM8 channels by menthol. We sought to identify additional plant compounds that are active on other types of TRP channels. We screened a library of extracts from 50 Chinese herbal plants using a calcium-imaging assay to find compounds active on TRPV3 and TRPV4 channels. An extract from the plant Andrographis paniculata potently activated TRPV4 channels. The extract was fractionated further, and the active compound was identified as bisandrographolide A (BAA). We used purified compound to characterize the activity of BAA on certain TRPV channel subtypes. Although BAA activated TRPV4 channels with an EC(50) of 790-950 nm, it did not activate or block activation of TRPV1, TRPV2, or TRPV3 channels. BAA activated a large TRPV4-like current in immortalized mouse keratinocytes (308 cells) that have been shown to express TRPV4 protein endogenously. This compound also activated TRPV4 currents in cell-free outside-out patches from HEK293T cells overexpressing TRPV4 cDNA, suggesting that BAA can activate the channel in a membrane-delimited manner. Another related compound, andrographolide, found in abundance in the plant Andrographis was unable to activate or block activation of TRPV4 channels. These experiments show that BAA activates TRPV4 channels, and we discuss the possibility that activation of TRPV4 by BAA could play a role in some of the effects of Andrographis extract described in traditional medicine.

  7. Cross-linking reveals laminin coiled-coil architecture

    PubMed Central

    Armony, Gad; Jacob, Etai; Moran, Toot; Levin, Yishai; Mehlman, Tevie; Levy, Yaakov; Fass, Deborah

    2016-01-01

    Laminin, an ∼800-kDa heterotrimeric protein, is a major functional component of the extracellular matrix, contributing to tissue development and maintenance. The unique architecture of laminin is not currently amenable to determination at high resolution, as its flexible and narrow segments complicate both crystallization and single-particle reconstruction by electron microscopy. Therefore, we used cross-linking and MS, evaluated using computational methods, to address key questions regarding laminin quaternary structure. This approach was particularly well suited to the ∼750-Å coiled coil that mediates trimer assembly, and our results support revision of the subunit order typically presented in laminin schematics. Furthermore, information on the subunit register in the coiled coil and cross-links to downstream domains provide insights into the self-assembly required for interaction with other extracellular matrix and cell surface proteins. PMID:27815530

  8. Inhibition of auxin transport and auxin signaling and treatment with far red light induces root coiling in the phospholipase-A mutant ppla-I-1. Significance for surface penetration?

    PubMed

    Perrineau, F; Wimalasekera, R; Effendi, Y; Scherer, G F E

    2016-06-01

    When grown on a non-penetretable at a surface angle of 45°, Arabidopsis roots form wave-like structures and, in wild type rarely, but in certain mutants the tip root even may form circles. These circles are called coils. The formation of coils depends on the complex interaction of circumnutation, gravitropism and negative thigmotropism where - at least - gravitropism is intimately linked to auxin transport and signaling. The knockout mutant of patatin-related phospholipase-AI-1 (pplaI-1) is an auxin-signaling mutant which forms moderately increased numbers of coils on tilted agar plates. We tested the effects of the auxin efflux transport inhibitor NPA (1-naphthylphtalamic acid) and of the influx transport inhibitor 1-NOA (1-naphthoxyacetic acid) which both further increased root coil formation. The pPLAI-1 inhibitors HELSS (haloenol lactone suicide substrate=E-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one) and ETYA (eicosatetraynoic acid) which are auxin signaling inhibitors also increased coil formation. In addition, far red light treatment increased coil formation. The results point out that a disturbance of auxin transport and signaling is one potential cause for root coils. As we show that the mutant pplaI-1 penetrates horizontal agar plates better than wild type plants root movements may help penetrating the soil.

  9. Electrospun Buckling Coils

    NASA Astrophysics Data System (ADS)

    Xin, Yu; Reneker, Darrell

    2009-03-01

    Electrospinning offers a useful way to produce fibers with micron and nanometer scale diameter. The present work deals with the buckling phenomenon characteristic of a jet impinging upon the surface of collector. A viscous jet may have either tensile or compressive forces along its axis. The periodic buckling that is often observed is attributed to the occurrence of compressive forces as the jet decelerates at the collector. With the increase of axial compressive stresses along the jet, a jet with circular cross sections first buckles by formation of sharp folds, and then by formation of coils. The resulting buckling patterns include zigzag patterns and coils that which can be controlled by changing parameters, such as density, viscosity, conductivity, voltage, polymer concentration, distance and volumetric flow rate. Uniformly buckled polymer fibers can be made at a rate of one turn per microsecond. An experimental apparatus was built to continuously collect buckling coils of nylon 6, from a water surface, into a multilayer sheet. These small ``springs'' and sheets will be tested for mechanical properties needed in biomedical applications.

  10. Dependence of B1+ and B1− Field Patterns of Surface Coils on the Electrical Properties of the Sample and the MR Operating Frequency

    PubMed Central

    Vaidya, Manushka V.; Collins, Christopher M.; Sodickson, Daniel K.; Brown, Ryan; Wiggins, Graham C.; Lattanzi, Riccardo

    2016-01-01

    In high field MRI, the spatial distribution of the radiofrequency magnetic (B1) field is usually affected by the presence of the sample. For hardware design and to aid interpretation of experimental results, it is important both to anticipate and to accurately simulate the behavior of these fields. Fields generated by a radiofrequency surface coil were simulated using dyadic Green’s functions, or experimentally measured over a range of frequencies inside an object whose electrical properties were varied to illustrate a variety of transmit (B1+) and receive (B1−) field patterns. In this work, we examine how changes in polarization of the field and interference of propagating waves in an object can affect the B1 spatial distribution. Results are explained conceptually using Maxwell’s equations and intuitive illustrations. We demonstrate that the electrical conductivity alters the spatial distribution of distinct polarized components of the field, causing “twisted” transmit and receive field patterns, and asymmetries between |B1+| and |B1−|. Additionally, interference patterns due to wavelength effects are observed at high field in samples with high relative permittivity and near-zero conductivity, but are not present in lossy samples due to the attenuation of propagating EM fields. This work provides a conceptual framework for understanding B1 spatial distributions for surface coils and can provide guidance for RF engineers. PMID:27795697

  11. Transport Vesicle Tethering at the Trans Golgi Network: Coiled Coil Proteins in Action

    PubMed Central

    Cheung, Pak-yan P.; Pfeffer, Suzanne R.

    2016-01-01

    The Golgi complex is decorated with so-called Golgin proteins that share a common feature: a large proportion of their amino acid sequences are predicted to form coiled-coil structures. The possible presence of extensive coiled coils implies that these proteins are highly elongated molecules that can extend a significant distance from the Golgi surface. This property would help them to capture or trap inbound transport vesicles and to tether Golgi mini-stacks together. This review will summarize our current understanding of coiled coil tethers that are needed for the receipt of transport vesicles at the trans Golgi network (TGN). How do long tethering proteins actually catch vesicles? Golgi-associated, coiled coil tethers contain numerous binding sites for small GTPases, SNARE proteins, and vesicle coat proteins. How are these interactions coordinated and are any or all of them important for the tethering process? Progress toward understanding these questions and remaining, unresolved mysteries will be discussed. PMID:27014693

  12. Kv3.4 channel function and dysfunction in nociceptors

    PubMed Central

    Ritter, David M; Zemel, Benjamin M; Lepore, Angelo C; Covarrubias, Manuel

    2015-01-01

    Recently, we reported the isolation of the Kv3.4 current in dorsal root ganglion (DRG) neurons and described dysregulation of this current in a spinal cord injury (SCI) model of chronic pain. These studies strongly suggest that rat Kv3.4 channels are major regulators of excitability in DRG neurons from pups and adult females, where they help determine action potential (AP) repolarization and spiking properties. Here, we characterized the Kv3.4 current in rat DRG neurons from adult males and show that it transfers 40–70% of the total repolarizing charge during the AP across all ages and sexes. Following SCI, we also found remodeling of the repolarizing currents during the AP. In the light of these studies, homomeric Kv3.4 channels expressed in DRG nociceptors are emerging novel targets that may help develop new approaches to treat neuropathic pain. PMID:26039360

  13. Kv3.4 channel function and dysfunction in nociceptors.

    PubMed

    Ritter, David M; Zemel, Benjamin M; Lepore, Angelo C; Covarrubias, Manuel

    2015-01-01

    Recently, we reported the isolation of the Kv3.4 current in dorsal root ganglion (DRG) neurons and described dysregulation of this current in a spinal cord injury (SCI) model of chronic pain. These studies strongly suggest that rat Kv3.4 channels are major regulators of excitability in DRG neurons from pups and adult females, where they help determine action potential (AP) repolarization and spiking properties. Here, we characterized the Kv3.4 current in rat DRG neurons from adult males and show that it transfers 40-70% of the total repolarizing charge during the AP across all ages and sexes. Following SCI, we also found remodeling of the repolarizing currents during the AP. In the light of these studies, homomeric Kv3.4 channels expressed in DRG nociceptors are emerging novel targets that may help develop new approaches to treat neuropathic pain.

  14. Dynamics of liquid rope coiling.

    PubMed

    Habibi, Mehdi; Maleki, Maniya; Golestanian, Ramin; Ribe, Neil M; Bonn, Daniel

    2006-12-01

    We present a combined experimental and numerical investigation of the coiling of a liquid "rope" falling on a solid surface, focusing on three little-explored aspects of the phenomenon: The time dependence of "inertio-gravitational" coiling, the systematic dependence of the radii of the coil and the rope on the experimental parameters, and the "secondary buckling" of the columnar structure generated by high-frequency coiling. Inertio-gravitational coiling is characterized by oscillations between states with different frequencies, and we present experimental observations of four distinct branches of such states in the frequency-fall height space. The transitions between coexisting states have no characteristic period, may take place with or without a change in the sense of rotation, and usually (but not always) occur via an intermediate "figure of eight" state. We present extensive laboratory measurements of the radii of the coil and of the rope within it, and show that they agree well with the predictions of a "slender-rope" numerical model. Finally, we use dimensional analysis to reveal a systematic variation of the critical column height for secondary buckling as a function of (dimensionless) flow rate and surface tension parameters.

  15. Coil Welding Aid

    NASA Technical Reports Server (NTRS)

    Wiesenbach, W. T.; Clark, M. C.

    1983-01-01

    Positioner holds coil inside cylinder during tack welding. Welding aid spaces turns of coil inside cylinder and applies contact pressure while coil is tack-welded to cylinder. Device facilitates fabrication of heat exchangers and other structures by eliminating hand-positioning and clamping of individual coil turns.

  16. Design and numerical evaluation of a volume coil array for parallel MR imaging at ultrahigh fields

    PubMed Central

    Pang, Yong; Wong, Ernest W.H.; Yu, Baiying

    2014-01-01

    In this work, we propose and investigate a volume coil array design method using different types of birdcage coils for MR imaging. Unlike the conventional radiofrequency (RF) coil arrays of which the array elements are surface coils, the proposed volume coil array consists of a set of independent volume coils including a conventional birdcage coil, a transverse birdcage coil, and a helix birdcage coil. The magnetic fluxes of these three birdcage coils are intrinsically cancelled, yielding a highly decoupled volume coil array. In contrast to conventional non-array type volume coils, the volume coil array would be beneficial in improving MR signal-to-noise ratio (SNR) and also gain the capability of implementing parallel imaging. The volume coil array is evaluated at the ultrahigh field of 7T using FDTD numerical simulations, and the g-factor map at different acceleration rates was also calculated to investigate its parallel imaging performance. PMID:24649435

  17. Comparison of (31)P saturation and inversion magnetization transfer in human liver and skeletal muscle using a clinical MR system and surface coils.

    PubMed

    Buehler, Tania; Kreis, Roland; Boesch, Chris

    2015-02-01

    (31)P MRS magnetization transfer ((31)P-MT) experiments allow the estimation of exchange rates of biochemical reactions, such as the creatine kinase equilibrium and adenosine triphosphate (ATP) synthesis. Although various (31)P-MT methods have been successfully used on isolated organs or animals, their application on humans in clinical scanners poses specific challenges. This study compared two major (31)P-MT methods on a clinical MR system using heteronuclear surface coils. Although saturation transfer (ST) is the most commonly used (31)P-MT method, sequences such as inversion transfer (IT) with short pulses might be better suited for the specific hardware and software limitations of a clinical scanner. In addition, small NMR-undetectable metabolite pools can transfer MT to NMR-visible pools during long saturation pulses, which is prevented with short pulses. (31)P-MT sequences were adapted for limited pulse length, for heteronuclear transmit-receive surface coils with inhomogeneous B1 , for the need for volume selection and for the inherently low signal-to-noise ratio (SNR) on a clinical 3-T MR system. The ST and IT sequences were applied to skeletal muscle and liver in 10 healthy volunteers. Monte-Carlo simulations were used to evaluate the behavior of the IT measurements with increasing imperfections. In skeletal muscle of the thigh, ATP synthesis resulted in forward reaction constants (k) of 0.074 ± 0.022 s(-1) (ST) and 0.137 ± 0.042 s(-1) (IT), whereas the creatine kinase reaction yielded 0.459 ± 0.089 s(-1) (IT). In the liver, ATP synthesis resulted in k = 0.267 ± 0.106 s(-1) (ST), whereas the IT experiment yielded no consistent results. ST results were close to literature values; however, the IT results were either much larger than the corresponding ST values and/or were widely scattered. To summarize, ST and IT experiments can both be implemented on a clinical body scanner with heteronuclear transmit-receive surface coils; however, ST results are

  18. Protective link for superconducting coil

    DOEpatents

    Umans, Stephen D.

    2009-12-08

    A superconducting coil system includes a superconducting coil and a protective link of superconducting material coupled to the superconducting coil. A rotating machine includes first and second coils and a protective link of superconducting material. The second coil is operable to rotate with respect to the first coil. One of the first and second coils is a superconducting coil. The protective link is coupled to the superconducting coil.

  19. Longitudinal evaluation of intramyocellular lipids (IMCLs) in tibialis anterior muscle of ob/ob and ob/+ control mice using a cryogenic surface coil at 9.4 T.

    PubMed

    Ye, Qiong; Danzer, Carsten Friedrich; Fuchs, Alexander; Krek, Wilhelm; Mueggler, Thomas; Baltes, Christof; Rudin, Markus

    2011-12-01

    Insulin resistance is a central feature of type II diabetes and is associated with alterations in skeletal muscle lipid metabolism, which manifest themselves, in part, in increased intramyocellular lipid (IMCL) accumulation. The objective of this study was to assess noninvasively the levels of IMCL longitudinally in the tibialis anterior muscle of Lep(ob) /Lep(ob) (ob/ob) mice, a genetic model of obesity and mild diabetes, and Lep(ob) /+ (ob/+) heterozygous control animals, using (1) H MRS at 9.4 T. The use of a cryogenic surface coil transceiver leads to significant increases in sensitivity. Method implementation included the assessment of the reproducibility and spatial heterogeneity of the IMCL signal and the determination of T(2) relaxation times, as IMCL levels were expressed relative to the total creatine signal, and therefore the signal ratios had to be corrected for differences in T(2) relaxation. IMCL levels were found to be significantly higher in ob/ob mice relative to ob/+ heterozygous control mice that do not develop disease. An increase in IMCL levels was observed for ob/ob mice until weeks 16/17; after this time point, IMCL levels decreased again, reaching final levels that were slightly higher than the initial values. These noninvasively detected alterations in skeletal muscle lipid metabolism in ob/ob mice were accompanied by a transient increase in plasma insulin concentrations. This study indicates that IMCL may be reliably assessed in mouse tibialis anterior muscle using a cryogenic surface coil, implying that (1) H MRS at 9.4 T represents a useful technology for the noninvasive measurement of changes in lipid metabolism in the skeletal muscle that accompany obesity.

  20. Pharmacological interference with protein-protein interactions mediated by coiled-coil motifs.

    PubMed

    Strauss, H M; Keller, S

    2008-01-01

    Coiled coils are bundles of intertwined alpha-helices that provide protein-protein interaction sites for the dynamic assembly and disassembly of protein complexes. The coiled-coil motif combines structural versatility and adaptability with mechanical strength and specificity. Multimeric proteins that rely on coiled-coil interactions are structurally and functionally very diverse, ranging from simple homodimeric transcription factors to elaborate heteromultimeric scaffolding clusters. Several coiled-coil-bearing proteins are of outstanding pharmacological importance, most notably SNARE proteins involved in vesicular trafficking of neurotransmitters and viral fusion proteins. Together with their crucial roles in many physiological and pathological processes, the structural simplicity and reversible nature of coiled-coil associations render them a promising target for pharmacological interference, as successfully exemplified by botulinum toxins and viral fusion inhibitors. The alpha-helical coiled coil is a ubiquitous protein domain that mediates highly specific homo- and heteromeric protein-protein interactions among a wide range of proteins. The coiled-coil motif was first proposed by Crick on the basis of X-ray diffraction data on alpha-keratin more than 50 years ago (Crick 1952, 1953) and nowadays belongs to the best-characterized protein interaction modules. By definition, a coiled coil is an oligomeric protein assembly consisting of several right-handed amphipathic alpha-helices that wind around each other into a superhelix (or a supercoil) in which the hydrophobic surfaces of the constituent helices are in continuous contact, forming a hydrophobic core. Both homomeric and heteromeric coiled coils with different stoichiometries are possible, and the helices can be aligned in either a parallel or an antiparallel topology (Harbury et al. 1993, 1994). Stoichiometry and topology are governed by the primary structure, that is, the sequence of the polypeptide chains

  1. Immune responses to coiled coil supramolecular biomaterials.

    PubMed

    Rudra, Jai S; Tripathi, Pulak K; Hildeman, David A; Jung, Jangwook P; Collier, Joel H

    2010-11-01

    Self-assembly has been increasingly utilized in recent years to create peptide-based biomaterials for 3D cell culture, tissue engineering, and regenerative medicine, but the molecular determinants of these materials' immunogenicity have remained largely unexplored. In this study, a set of molecules that self-assembled through coiled coil oligomerization was designed and synthesized, and immune responses against them were investigated in mice. Experimental groups spanned a range of oligomerization behaviors and included a peptide from the coiled coil region of mouse fibrin that did not form supramolecular structures, an engineered version of this peptide that formed coiled coil bundles, and a peptide-PEG-peptide triblock bioconjugate that formed coiled coil multimers and supramolecular aggregates. In mice, the native peptide and engineered peptide did not produce any detectable antibody response, and none of the materials elicited detectable peptide-specific T cell responses, as evidenced by the absence of IL-2 and interferon-gamma in cultures of peptide-challenged splenocytes or draining lymph node cells. However, specific antibody responses were elevated in mice injected with the multimerizing peptide-PEG-peptide. Minimal changes in secondary structure were observed between the engineered peptide and the triblock peptide-PEG-peptide, making it possible that the triblock's multimerization was responsible for this antibody response.

  2. TPX correction coil studies

    SciTech Connect

    Hanson, J.D.

    1994-11-03

    Error correction coils are planned for the TPX (Tokamak Plasma Experiment) in order to avoid error field induced locked modes and disruption. The FT (Fix Tokamak) code is used to evaluate the ability of these correction coils to remove islands caused by symmetry breaking magnetic field errors. The proposed correction coils are capable of correcting a variety of error fields.

  3. Cooling arrangement for a superconducting coil

    DOEpatents

    Herd, Kenneth Gordon; Laskaris, Evangelos Trifon

    1998-06-30

    A superconducting device, such as a superconducting rotor for a generator or motor. A vacuum enclosure has an interior wall surrounding a cavity containing a vacuum. A superconductive coil is placed in the cavity. A generally-annularly-arranged, thermally-conductive sheet has an inward-facing surface contacting generally the entire outward-facing surface of the superconductive coil. A generally-annularly-arranged coolant tube contains a cryogenic fluid and contacts a generally-circumferential portion of the outward-facing surface of the sheet. A generally-annularly-arranged, thermally-insulative coil overwrap generally circumferentially surrounds the sheet. The coolant tube and the inward-facing surface of the coil overwrap together contact generally the entire outward-facing surface of the sheet.

  4. Cooling arrangement for a superconducting coil

    DOEpatents

    Herd, K.G.; Laskaris, E.T.

    1998-06-30

    A superconducting device is disclosed, such as a superconducting rotor for a generator or motor. A vacuum enclosure has an interior wall surrounding a cavity containing a vacuum. A superconductive coil is placed in the cavity. A generally-annularly-arranged, thermally-conductive sheet has an inward-facing surface contacting generally the entire outward-facing surface of the superconductive coil. A generally-annularly-arranged coolant tube contains a cryogenic fluid and contacts a generally-circumferential portion of the outward-facing surface of the sheet. A generally-annularly-arranged, thermally-insulative coil overwrap generally circumferentially surrounds the sheet. The coolant tube and the inward-facing surface of the coil overwrap together contact generally the entire outward-facing surface of the sheet. 3 figs.

  5. Electromagnetic pump stator coil

    DOEpatents

    Fanning, Alan W.; Dahl, Leslie R.

    1996-01-01

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom.

  6. Electromagnetic pump stator coil

    DOEpatents

    Fanning, A.W.; Dahl, L.R.

    1996-06-25

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom. 9 figs.

  7. Depth-resolved surface coil MRS (DRESS)-localized dynamic (31) P-MRS of the exercising human gastrocnemius muscle at 7 T.

    PubMed

    Valkovič, Ladislav; Chmelík, Marek; Just Kukurová, Ivica; Jakubová, Michaela; Kipfelsberger, Monika Christina; Krumpolec, Patrik; Tušek Jelenc, Marjeta; Bogner, Wolfgang; Meyerspeer, Martin; Ukropec, Jozef; Frollo, Ivan; Ukropcová, Barbara; Trattnig, Siegfried; Krššák, Martin

    2014-11-01

    Dynamic (31) P-MRS with sufficiently high temporal resolution enables the non-invasive evaluation of oxidative muscle metabolism through the measurement of phosphocreatine (PCr) recovery after exercise. Recently, single-voxel localized (31) P-MRS was compared with surface coil localization in a dynamic fashion, and was shown to provide higher anatomical and physiological specificity. However, the relatively long TE needed for the single-voxel localization scheme with adiabatic pulses limits the quantification of J-coupled spin systems [e.g. adenosine triphosphate (ATP)]. Therefore, the aim of this study was to evaluate depth-resolved surface coil MRS (DRESS) as an alternative localization method capable of free induction decay (FID) acquisition for dynamic (31) P-MRS at 7 T. The localization performance of the DRESS sequence was tested in a phantom. Subsequently, two dynamic examinations of plantar flexions at 25% of maximum voluntary contraction were conducted in 10 volunteers, one examination with and one without spatial localization. The DRESS slab was positioned obliquely over the gastrocnemius medialis muscle, avoiding other calf muscles. Under the same load, significant differences in PCr signal drop (31.2 ± 16.0% versus 43.3 ± 23.4%), end exercise pH (7.06 ± 0.02 versus 6.96 ± 0.11), initial recovery rate (0.24 ± 0.13 mm/s versus 0.35 ± 0.18 mm/s) and maximum oxidative flux (0.41 ± 0.14 mm/s versus 0.54 ± 0.16 mm/s) were found between the non-localized and DRESS-localized data, respectively. Splitting of the inorganic phosphate (Pi) signal was observed in several non-localized datasets, but in none of the DRESS-localized datasets. Our results suggest that the application of the DRESS localization scheme yielded good spatial selection, and provided muscle-specific insight into oxidative metabolism, even at a relatively low exercise load. In addition, the non-echo-based FID acquisition allowed for reliable detection of ATP resonances, and therefore

  8. Engineered coiled-coil protein microfibers.

    PubMed

    Hume, Jasmin; Sun, Jennifer; Jacquet, Rudy; Renfrew, P Douglas; Martin, Jesse A; Bonneau, Richard; Gilchrist, M Lane; Montclare, Jin Kim

    2014-10-13

    The fabrication of de novo proteins able to self-assemble on the nano- to meso-length scales is critical in the development of protein-based biomaterials in nanotechnology and medicine. Here we report the design and characterization of a protein engineered coiled-coil that not only assembles into microfibers, but also can bind hydrophobic small molecules. Under ambient conditions, the protein forms fibers with nanoscale structure possessing large aspect ratios formed by bundles of α-helical homopentameric assemblies, which further assemble into mesoscale fibers in the presence of curcumin through aggregation. Surprisingly, these biosynthesized fibers are able to form in conditions of remarkably low concentrations. Unlike previously designed coiled-coil fibers, these engineered protein microfibers can bind the small molecule curcumin throughout the assembly, serving as a depot for encapsulation and delivery of other chemical agents within protein-based 3D microenvironments.

  9. Noncationic Rigid and Anisotropic Coiled-Coil Proteins Exhibit Cell-Penetration Activity.

    PubMed

    Nakayama, Norihisa; Hagiwara, Kyoji; Ito, Yoshihiro; Ijiro, Kuniharu; Osada, Yoshihito; Sano, Ken-ichi

    2015-08-04

    Numerous cationic peptides that penetrate cells have been studied intensively as drug delivery system carriers for cellular delivery. However, cationic molecules tend to be cytotoxic and cause inflammation, and their stability in the blood is usually low. We have previously demonstrated that a rigid and fibrous cationic coiled-coil protein exhibited cell-penetrating ability superior to that of previously reported cell-penetrating peptides. Making use of structural properties, here we describe the cell-penetrating activity of a rigid and fibrous coiled-coil protein with a noncationic surface. A fibrous coiled-coil protein of pI 6.5 penetrated 100% of the cells tested in vitro at a concentration of 500 nM, which is comparable to that of previously reported cell-penetrating peptides. We also investigated the effect of cell-strain dependency and short-term cytotoxicity.

  10. Helically Coiled Graphene Nanoribbons.

    PubMed

    Daigle, Maxime; Miao, Dandan; Lucotti, Andrea; Tommasini, Matteo; Morin, Jean-François

    2017-03-07

    Graphene is a zero-gap, semiconducting 2D material that exhibits outstanding charge-transport properties. One way to open a band gap and make graphene useful as a semiconducting material is to confine the electron delocalization in one dimension through the preparation of graphene nanoribbons (GNR). Although several methods have been reported so far, solution-phase, bottom-up synthesis is the most promising in terms of structural precision and large-scale production. Herein, we report the synthesis of a well-defined, helically coiled GNR from a polychlorinated poly(m-phenylene) through a regioselective photochemical cyclodehydrochlorination (CDHC) reaction. The structure of the helical GNR was confirmed by (1) H NMR, FT-IR, XPS, TEM, and Raman spectroscopy. This Riemann surface-like GNR has a band gap of 2.15 eV and is highly emissive in the visible region, both in solution and the solid state.

  11. Functional investigation of the plant-specific long coiled-coil proteins PAMP-INDUCED COILED-COIL (PICC) and PICC-LIKE (PICL) in Arabidopsis thaliana.

    PubMed

    Venkatakrishnan, Sowmya; Mackey, David; Meier, Iris

    2013-01-01

    We have identified and characterized two Arabidopsis long coiled-coil proteins PAMP-INDUCED COILED-COIL (PICC) and PICC-LIKE (PICL). PICC (147 kDa) and PICL (87 kDa) are paralogs that consist predominantly of a long coiled-coil domain (expanded in PICC), with a predicted transmembrane domain at the immediate C-terminus. Orthologs of PICC and PICL were found exclusively in vascular plants. PICC and PICL GFP fusion proteins are anchored to the cytoplasmic surface of the endoplasmic reticulum (ER) membrane by a C-terminal transmembrane domain and a short tail domain, via a tail-anchoring mechanism. T-DNA-insertion mutants of PICC and PICL as well as the double mutant show an increased sensitivity to the plant abiotic stress hormone abscisic acid (ABA) in a post-germination growth response. PICC, but not PICL gene expression is induced by the bacterial pathogen-associated molecular pattern (PAMP) flg22. T-DNA insertion alleles of PICC, but not PICL, show increased susceptibility to the non-virulent strain P. syringae pv. tomato DC3000 hrcC, but not to the virulent strain P. syringae pv. tomato DC3000. This suggests that PICC mutants are compromised in PAMP-triggered immunity (PTI). The data presented here provide first evidence for the involvement of a plant long coiled-coil protein in a plant defense response.

  12. Functional Investigation of the Plant-Specific Long Coiled-Coil Proteins PAMP-INDUCED COILED-COIL (PICC) and PICC-LIKE (PICL) in Arabidopsis thaliana

    PubMed Central

    Venkatakrishnan, Sowmya; Mackey, David; Meier, Iris

    2013-01-01

    We have identified and characterized two Arabidopsis long coiled-coil proteins PAMP-INDUCED COILED-COIL (PICC) and PICC-LIKE (PICL). PICC (147 kDa) and PICL (87 kDa) are paralogs that consist predominantly of a long coiled-coil domain (expanded in PICC), with a predicted transmembrane domain at the immediate C-terminus. Orthologs of PICC and PICL were found exclusively in vascular plants. PICC and PICL GFP fusion proteins are anchored to the cytoplasmic surface of the endoplasmic reticulum (ER) membrane by a C-terminal transmembrane domain and a short tail domain, via a tail-anchoring mechanism. T-DNA-insertion mutants of PICC and PICL as well as the double mutant show an increased sensitivity to the plant abiotic stress hormone abscisic acid (ABA) in a post-germination growth response. PICC, but not PICL gene expression is induced by the bacterial pathogen-associated molecular pattern (PAMP) flg22. T-DNA insertion alleles of PICC, but not PICL, show increased susceptibility to the non-virulent strain P. syringae pv. tomato DC3000 hrcC, but not to the virulent strain P. syringae pv. tomato DC3000. This suggests that PICC mutants are compromised in PAMP-triggered immunity (PTI). The data presented here provide first evidence for the involvement of a plant long coiled-coil protein in a plant defense response. PMID:23451199

  13. Optimal Coil Orientation for Transcranial Magnetic Stimulation

    PubMed Central

    Richter, Lars; Neumann, Gunnar; Oung, Stephen; Schweikard, Achim; Trillenberg, Peter

    2013-01-01

    We study the impact of coil orientation on the motor threshold (MT) and present an optimal coil orientation for stimulation of the foot. The result can be compared to results of models that predict this orientation from electrodynamic properties of the media in the skull and from orientations of cells, respectively. We used a robotized TMS system for precise coil placement and recorded motor-evoked potentials with surface electrodes on the abductor hallucis muscle of the right foot in 8 healthy control subjects. First, we performed a hot-spot search in standard (lateral) orientation and then rotated the coil in steps of 10° or 20°. At each step we estimated the MT. For navigated stimulation and for correlation with the underlying anatomy a structural MRI scan was obtained. Optimal coil orientation was 33.1±18.3° anteriorly in relation to the standard lateral orientation. In this orientation the threshold was 54±18% in units of maximum stimulator output. There was a significant difference of 8.0±5.9% between the MTs at optimal and at standard orientation. The optimal coil orientations were significantly correlated with the direction perpendicular to the postcentral gyrus (). Robotized TMS facilitates sufficiently precise coil positioning and orientation to study even small variations of the MT with coil orientation. The deviations from standard orientation are more closely matched by models based on field propagation in media than by models based on orientations of pyramidal cells. PMID:23593200

  14. Superconducting magnetic coil

    DOEpatents

    Aized, Dawood; Schwall, Robert E.

    1996-06-11

    A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil.

  15. Superconducting magnetic coil

    DOEpatents

    Aized, D.; Schwall, R.E.

    1999-06-22

    A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil. 15 figs.

  16. Superconducting magnetic coil

    DOEpatents

    Aized, Dawood; Schwall, Robert E.

    1999-06-22

    A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil.

  17. Wedding ring shaped excitation coil

    DOEpatents

    MacLennan, Donald A.; Tsai, Peter

    2001-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency.

  18. Coiling Viscous Jets

    NASA Astrophysics Data System (ADS)

    Mahadevan, L.

    1996-11-01

    A thin stream of glycerine or other viscous fluid poured onto a horizontal plane from a sufficient height piles up in a regular coil. In its steady state, this motion is analogous to the coiling of a flexible rope (L. Mahadevan and J.B. Keller, Proc. Roy. Soc.(A) to appear.). This analogy is used to solve the nonlinear free-boundary problem for the frequency of coiling and the coil radius. The results are compared with experimental results that go back to the the work of G.I. Taylor (1969).

  19. Coil system for plasmoid thruster

    NASA Technical Reports Server (NTRS)

    Eskridge, Richard H. (Inventor); Lee, Michael H. (Inventor); Martin, Adam K. (Inventor); Fimognari, Peter J. (Inventor)

    2010-01-01

    A coil system for a plasmoid thruster includes a bias coil, a drive coil and field coils. The bias and drive coils are interleaved with one another as they are helically wound about a conical region. A first field coil defines a first passage at one end of the conical region, and is connected in series with the bias coil. A second field coil defines a second passage at an opposing end of the conical region, and is connected in series with the bias coil.

  20. A new stellarator coil design tool using space curves

    NASA Astrophysics Data System (ADS)

    Zhu, Caoxiang; Hudson, Stuart; Breslau, Joshua; Lazerson, Samuel; Song, Yuntao; Wan, Yuanxi

    2016-10-01

    Finding easy-to-build coils has always been critical for stellarator design. Conventional approaches assume a toroidal ``winding'' surface. Either a surface current potential is constructed using a Green's function; or a discrete set of filamentary coils lying on the winding surface is non-linearly optimized. The winding surface concept ensures that the coils are separated from the plasma surface; however, requiring the coils lie on a given winding surface may overly constrain the coil optimization process. In this work, we investigate whether a winding surface is required. Our starting point is to represent each discrete coil as an arbitrary closed curve embedded in 3D space. From the Fundamental Theorem for Curves, such curves are uniquely described by the curvature and torsion functions. Our representation does not need a winding surface and can allow coils to evolve arbitrarily. We have constructed different penalty functions, F, that incorporate both the `physics' and `engineering' constraints. The first and second derivatives of F with respect to the parameters describing the coils are constructed analytically and are exploited to enable fast optimization algorithms for finding minima. Illustrations of coils for W7X and other stellarators will be presented. China Scholarship Council.

  1. A 3T Sodium and Proton Composite Array Breast Coil

    PubMed Central

    Kaggie, Joshua D.; Hadley, J. Rock; Badal, James; Campbell, John R.; Park, Daniel J.; Parker, Dennis L.; Morrell, Glen; Newbould, Rexford D.; Wood, Ali F.; Bangerter, Neal K.

    2013-01-01

    Purpose The objective of this study was to determine whether a sodium phased array would improve sodium breast MRI at 3T. The secondary objective was to create acceptable proton images with the sodium phased array in place. Methods A novel composite array for combined proton/sodium 3T breast MRI is compared to a coil with a single proton and sodium channel. The composite array consists of a 7-channel sodium receive array, a larger sodium transmit coil, and a 4-channel proton transceive array. The new composite array design utilizes smaller sodium receive loops than typically used in sodium imaging, uses novel decoupling methods between the receive loops and transmit loops, and uses a novel multi-channel proton transceive coil. The proton transceive coil reduces coupling between proton and sodium elements by intersecting the constituent loops to reduce their mutual inductance. The coil used for comparison consists of a concentric sodium and proton loop with passive decoupling traps. Results The composite array coil demonstrates a 2–5x improvement in SNR for sodium imaging and similar SNR for proton imaging when compared to a simple single-loop dual resonant design. Conclusion The improved SNR of the composite array gives breast sodium images of unprecedented quality in reasonable scan times. PMID:24105740

  2. Coiled bodies without coilin.

    PubMed Central

    Bauer, D W; Gall, J G

    1997-01-01

    Nuclei assembled in vitro in Xenopus egg extract contain coiled bodies that have components from three different RNA processing pathways: pre-mRNA splicing, pre-rRNA processing, and histone pre-mRNA 3'-end formation. In addition, they contain SPH-1, the Xenopus homologue of p80-coilin, a protein characteristic of coiled bodies. To determine whether coilin is an essential structural component of the coiled body, we removed it from the egg extract by immunoprecipitation. We showed that nuclei with bodies morphologically identical to coiled bodies (at the light microscope level) formed in such coilin-depleted extract. As expected, these bodies did not stain with antibodies against coilin. Moreover, they failed to stain with an antibody against the Sm proteins, although Sm proteins associated with snRNAs were still present in the extract. Staining of the coilin- and Sm-depleted coiled bodies was normal with antibodies against two nucleolar proteins, fibrillarin and nucleolin. Similar results were observed when Sm proteins were depleted from egg extract: staining of the coiled bodies with antibodies against the Sm proteins and coilin was markedly reduced but bright nucleolin and fibrillarin staining remained. These immunodepletion experiments demonstrate an interdependence between coilin and Sm snRNPs and suggest that neither is essential for assembly of nucleolar components in coiled bodies. We propose that coiled bodies are structurally heterogeneous organelles in which the components of the three RNA processing pathways may occur in separate compartments. Images PMID:9017596

  3. MEMS switch integrated radio frequency coils and arrays for magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Bulumulla, S. B.; Park, K. J.; Fiveland, E.; Iannotti, J.; Robb, F.

    2017-02-01

    Surface coils are widely used in magnetic resonance imaging and spectroscopy. While smaller diameter coils produce higher signal to noise ratio (SNR) closer to the coil, imaging larger fields of view or greater distance into the sample requires a larger overall size array or, in the case of a channel count limited system, larger diameter coils. In this work, we consider reconfiguring the geometry of coils and coil arrays such that the same coil or coil array may be used in multiple field of view imaging. A custom designed microelectromechanical systems switch, compatible with magnetic resonance imaging, is used to switch in/out conductive sections and components to reconfigure coils. The switch does not degrade the SNR and can be opened/closed in 10 μ s, leading to rapid reconfiguration. Results from a single coil, configurable between small/large configurations, and a two-coil phased array, configurable between spine/torso modes, are presented.

  4. Method for manufacturing a rotor having superconducting coils

    DOEpatents

    Driscoll, David I.; Shoykhet, Boris A.

    2001-01-01

    A method and apparatus for manufacturing a rotor for use with a rotating machine is provided that employs a superconducting coil on the rotor. An adhesive is applied to an outer surface of the rotor body, which may include a groove disposed within an outer surface of the rotor body. A superconducting coil is then mounted onto the rotor body such that the adhesive bonds the superconducting coil to the rotor body.

  5. Intelligent shell feedback control in EXTRAP T2R reversed field pinch with partial coverage of the toroidal surface by a discrete active coil array

    NASA Astrophysics Data System (ADS)

    Yadikin, D.; Brunsell, P. R.; Drake, J. R.

    2006-01-01

    An active feedback system is required for long pulse operation of the reversed field pinch (RFP) device to suppress resistive wall modes (RWMs). A general feature of a feedback system using a discrete active coil array is a coupling effect which arises when a set of side band modes determined by the number of active coils is produced. Recent results obtained on the EXTRAP T2R RFP demonstrated the suppression of independent m = 1 RWMs using an active feedback system with a two-dimensional array of discrete active coils in the poloidal and toroidal directions. One of the feedback algorithms used is the intelligent shell feedback scheme. Active feedback systems having different number of active coils in the poloidal (Mc) and toroidal (Nc) directions (Mc × Nc = 2 × 32 and Mc × Nc = 4 × 16) are studied. Different side band effects are seen for these configurations. A significant prolongation of the plasma discharge is achieved for the intelligent shell feedback scheme using the 2 × 32 active coil configuration. This is attributed to the side band sets including only one of the dominant unstable RWMs and avoiding coupling to resonant modes. Analog proportional-integral-derivative controllers are used in the feedback system. Regimes with different values of the proportional gain are studied. The requirement of the proportional-integral control for low proportional gain and proportional-derivative control for high proportional gain is seen in the experiments.

  6. Underbalanced coiled tubing sidetrack successful

    SciTech Connect

    Adam, J.; Berry, M.

    1995-12-18

    The technique of drilling through a completion string, underbalanced, with coiled tubing eliminated some of the problems encountered with overbalanced drilling in a group of offset wells. This project confirmed that performing drilling operations in live wells can be carried out safely and effectively. Dalen is a sour gas field in the eastern part of The Netherlands and produces from vertical fractures in the Zechstein carbonate reservoir. The proposal for Dalen 2 was to abandon the lower section of the original hole and subsequently sidetrack conventionally to the top of the reservoir, run and cement a 5-in. liner, complete the well with a 5-in. monobore completion, and install the christmas tree. This part of the operation would be performed with a workover hoist. Thereafter, a 3 3/4-in. hole would be drilled through the completion and into the reservoir, underbalanced with coiled tubing. The drilling proposal had to address a number of key issues: creating underbalanced conditions; handling sour gas production at surface; handling and treating drilling fluids at surface; removing drilled solids from the returned fluid system; and deploying a long coiled tubing drilling bottom hole assembly (BHA) into a live well. The paper discusses planning, legislative issues, well preparation, the drilling program, and lessons learned.

  7. Improved SNR of phased-array PERES coils via simulation study.

    PubMed

    Rodríguez, Alfredo O; Medina, Lucía

    2005-09-21

    A computational comparison of signal-to-noise ratio (SNR) was performed between a conventional phased array of two circular-shaped coils and a petal resonator surface array. The quasi-static model and phased-array optimum SNR were combined to derive an SNR formula for each array. Analysis of mutual inductance between coil petals was carried out to compute the optimal coil separation and optimum number of petal coils. Mutual interaction between coil arrays was not included in the model because this does not drastically affect coil performance. Phased arrays of PERES coils show a 114% improvement in SNR over that of the simplest circular configuration.

  8. Coil spring venting arrangement

    DOEpatents

    McCugh, R.M.

    1975-10-21

    A simple venting device for trapped gas pockets in hydraulic systems is inserted through a small access passages, operated remotely, and removed completely. The device comprises a small diameter, closely wound coil spring which is pushed through a guide temporarily inserted in the access passage. The guide has a central passageway which directs the coil spring radially upward into the pocket, so that, with the guide properly positioned for depth and properly oriented, the coil spring can be pushed up into the top of the pocket to vent it. By positioning a seal around the free end of the guide, the spring and guide are removed and the passage is sealed.

  9. Correction coil cable

    DOEpatents

    Wang, S.T.

    1994-11-01

    A wire cable assembly adapted for the winding of electrical coils is taught. A primary intended use is for use in particle tube assemblies for the Superconducting Super Collider. The correction coil cables have wires collected in wire array with a center rib sandwiched therebetween to form a core assembly. The core assembly is surrounded by an assembly housing having an inner spiral wrap and a counter wound outer spiral wrap. An alternate embodiment of the invention is rolled into a keystoned shape to improve radial alignment of the correction coil cable on a particle tube in a particle tube assembly. 7 figs.

  10. A classic zinc finger from friend of GATA mediates an interaction with the coiled-coil of transforming acidic coiled-coil 3.

    PubMed

    Simpson, Raina J Y; Yi Lee, Stella Hoi; Bartle, Natalie; Sum, Eleanor Y; Visvader, Jane E; Matthews, Jacqueline M; Mackay, Joel P; Crossley, Merlin

    2004-09-17

    Classic zinc finger domains (cZFs) consist of a beta-hairpin followed by an alpha-helix. They are among the most abundant of all protein domains and are often found in tandem arrays in DNA-binding proteins, with each finger contributing an alpha-helix to effect sequence-specific DNA recognition. Lone cZFs, not found in tandem arrays, have been postulated to function in protein interactions. We have studied the transcriptional co-regulator Friend of GATA (FOG), which contains nine zinc fingers. We have discovered that the third cZF of FOG contacts a coiled-coil domain in the centrosomal protein transforming acidic coiled-coil 3 (TACC3). Although FOG-ZF3 exhibited low solubility, we have used a combination of mutational mapping and protein engineering to generate a derivative that was suitable for in vitro and structural analysis. We report that the alpha-helix of FOG-ZF3 recognizes a C-terminal portion of the TACC3 coiled-coil. Remarkably, the alpha-helical surface utilized by FOG-ZF3 is the same surface responsible for the well established sequence-specific DNA-binding properties of many other cZFs. Our data demonstrate the versatility of cZFs and have implications for the analysis of many as yet uncharacterized cZF proteins.

  11. Coil Knotting during Endovascular Coil Embolization for Ruptured MCA Aneurysm

    PubMed Central

    Kwon, S.C.; Lyo, I.U.; Shin, S.H.; Park, J.B.; Kim, Y.

    2008-01-01

    Summary Complications during coil embolization of cerebral aneurysms include thromboembolic events, hemorrhagic complications related to procedural aneurysmal rupture and parent vessel perforation, and coil-related complications. The present report describes a rare coil-related complication involving spontaneous coil knotting. PMID:20557732

  12. Membrane fusion mediated by coiled coils: a hypothesis.

    PubMed Central

    Bentz, J

    2000-01-01

    A molecular model of the low-pH-induced membrane fusion by influenza hemagglutinin (HA) is proposed based upon the hypothesis that the conformational change to the extended coiled coil creates a high-energy hydrophobic membrane defect in the viral envelope or HA expressing cell. It is known that 1) an aggregate of at least eight HAs is required at the fusion site, yet only two or three of these HAs need to undergo the "essential" conformational change for the first fusion pore to form (Bentz, J. 2000. Biophys. J. 78:000-000); 2) the formation of the first fusion pore signifies a stage of restricted lipid flow into the nascent fusion site; and 3) some HAs can partially insert their fusion peptides into their own viral envelopes at low pH. This suggests that the committed step for HA-mediated fusion begins with a tightly packed aggregate of HAs whose fusion peptides are inserted into their own viral envelope, which causes restricted lateral lipid flow within the HA aggregate. The transition of two or three HAs in the center of the aggregate to the extended coiled coil extracts the fusion peptide and creates a hydrophobic defect in the outer monolayer of the virion, which is stabilized by the closely packed HAs. These HAs are inhibited from diffusing away from the site to admit lateral lipid flow, in part because that would initially increase the surface area of hydrophobic exposure. The other obvious pathway to heal this hydrophobic defect, or some descendent, is recruitment of lipids from the outer monolayer of the apposed target membrane, i.e., fusion. Other viral fusion proteins and the SNARE fusion protein complex appear to fit within this hypothesis. PMID:10653801

  13. A periodic table of coiled-coil protein structures.

    PubMed

    Moutevelis, Efrosini; Woolfson, Derek N

    2009-01-23

    Coiled coils are protein structure domains with two or more alpha-helices packed together via interlacing of side chains known as knob-into-hole packing. We analysed and classified a large set of coiled-coil structures using a combination of automated and manual methods. This led to a systematic classification that we termed a "periodic table of coiled coils," which we have made available at http://coiledcoils.chm.bris.ac.uk/ccplus/search/periodic_table. In this table, coiled-coil assemblies are arranged in columns with increasing numbers of alpha-helices and in rows of increased complexity. The table provides a framework for understanding possibilities in and limits on coiled-coil structures and a basis for future prediction, engineering and design studies.

  14. Mitochondrial Proteins Containing Coiled-Coil-Helix-Coiled-Coil-Helix (CHCH) Domains in Health and Disease.

    PubMed

    Modjtahedi, Nazanine; Tokatlidis, Kostas; Dessen, Philippe; Kroemer, Guido

    2016-03-01

    Members of the coiled-coil-helix-coiled-coil-helix (CHCH) domain-containing protein family that carry (CX9C) type motifs are imported into the mitochondrion with the help of the disulfide relay-dependent MIA import pathway. These evolutionarily conserved proteins are emerging as new cellular factors that control mitochondrial respiration, redox regulation, lipid homeostasis, and membrane ultrastructure and dynamics. We discuss recent insights on the activity of known (CX9C) motif-carrying proteins in mammals and review current data implicating the Mia40/CHCHD4 import machinery in the regulation of their mitochondrial import. Recent findings and the identification of disease-associated mutations in specific (CX9C) motif-carrying proteins have highlighted members of this family of proteins as potential therapeutic targets in a variety of human disorders.

  15. Borehole induction coil transmitter

    DOEpatents

    Holladay, Gale; Wilt, Michael J.

    2002-01-01

    A borehole induction coil transmitter which is a part of a cross-borehole electromagnetic field system that is used for underground imaging applications. The transmitter consists of four major parts: 1) a wound ferrite or mu-metal core, 2) an array of tuning capacitors, 3) a current driver circuit board, and 4) a flux monitor. The core is wound with several hundred turns of wire and connected in series with the capacitor array, to produce a tuned coil. This tuned coil uses internal circuitry to generate sinusoidal signals that are transmitted through the earth to a receiver coil in another borehole. The transmitter can operate at frequencies from 1-200 kHz and supplies sufficient power to permit the field system to operate in boreholes separated by up to 400 meters.

  16. Linear Rogowski coil

    NASA Astrophysics Data System (ADS)

    Nassisi, V.; Delle Side, D.

    2017-02-01

    Nowadays, the employment and development of fast current pulses require sophisticated systems to perform measurements. Rogowski coils are used to diagnose cylindrical shaped beams; therefore, they are designed and built with a toroidal structure. Recently, to perform experiments of radiofrequency biophysical stresses, flat transmission lines have been developed. Therefore, in this work we developed a linear Rogowski coil to detect current pulses inside flat conductors. The system is first approached by means of transmission line theory. We found that, if the pulse width to be diagnosed is comparable with the propagation time of the signal in the detector, it is necessary to impose a uniform current as input pulse, or to use short coils. We further analysed the effect of the resistance of the coil and the influence of its magnetic properties. As a result, the device we developed is able to record pulses lasting for some hundreds of nanoseconds, depending on the inductance, load impedance, and resistance of the coil. Furthermore, its response is characterized by a sub-nanosecond rise time (˜100 ps). The attenuation coefficient depends mainly on the turn number of the coil, while the fidelity of the response depends both on the magnetic core characteristics and on the current distribution along the plane conductors.

  17. Linear Rogowski coil.

    PubMed

    Nassisi, V; Delle Side, D

    2017-02-01

    Nowadays, the employment and development of fast current pulses require sophisticated systems to perform measurements. Rogowski coils are used to diagnose cylindrical shaped beams; therefore, they are designed and built with a toroidal structure. Recently, to perform experiments of radiofrequency biophysical stresses, flat transmission lines have been developed. Therefore, in this work we developed a linear Rogowski coil to detect current pulses inside flat conductors. The system is first approached by means of transmission line theory. We found that, if the pulse width to be diagnosed is comparable with the propagation time of the signal in the detector, it is necessary to impose a uniform current as input pulse, or to use short coils. We further analysed the effect of the resistance of the coil and the influence of its magnetic properties. As a result, the device we developed is able to record pulses lasting for some hundreds of nanoseconds, depending on the inductance, load impedance, and resistance of the coil. Furthermore, its response is characterized by a sub-nanosecond rise time (∼100 ps). The attenuation coefficient depends mainly on the turn number of the coil, while the fidelity of the response depends both on the magnetic core characteristics and on the current distribution along the plane conductors.

  18. NCSX Toroidal Field Coil Design

    SciTech Connect

    Kalish, M.; Rushinski, J.; Myatt, L.; Brooks, A.; Dahlgren, F.; Chrzanowski, J.; Reiersen, W.; Freudenberg, K.

    2005-10-07

    The National Compact Stellarator Experiment (NCSX) is an experimental device whose design and construction is underway at the Department of Energy's Princeton Plasma Physics Laboratory (PPPL). The primary coil systems for the NCSX device consist of the twisted plasma-shaping Modular Coils, the Poloidal Field Coils, and the Toroidal Field (TF) Coils. The TF Coils are D-shaped coils wound from hollow copper conductor, and vacuum impregnated with a glass-epoxy resin system. There are 18 identical, equally spaced TF coils providing 1/R field at the plasma. They operate within a cryostat, and are cooled by LN2, nominally, to 80K. Wedge shaped castings are assembled to the inboard face of these coils, so that inward radial loads are reacted via the nesting of each of the coils against their adjacent partners. This paper outlines the TF Coil design methodology, reviews the analysis results, and summarizes how the design and analysis support the design requirements.

  19. Modulation of elasticity in functionally distinct domains of the tropomyosin coiled-coil.

    PubMed

    Lakkaraju, Sirish Kaushik; Hwang, Wonmuk

    2009-03-01

    Alpha-helical coiled-coils are common protein structural motifs. Whereas vast information is available regarding their structure, folding, and stability, far less is known about their elastic properties, even though they play mechanical roles in many cases such as tropomyosin in muscle contraction or neck stalks of kinesin or myosin motor proteins. Using computer simulations, we characterized elastic properties of coiled-coils, either globally or locally. Global bending stiffness of standard leucine zipper coiled-coils was calculated using normal mode analysis. Mutations in hydrophobic residues involved in the knob-into-hole interface between the two alpha-helices affect elasticity significantly, whereas charged side chains forming inter-helical salt bridges do not. This suggests that coiled-coils with less regular heptad periodicity may have regional variations in flexibility. We show this by the flexibility map of tropomyosin, which was constructed by a local fluctuation analysis. Overall, flexibility varies by more than twofold and increases towards the C-terminal region of the molecule. Describing the coiled-coil as a twisted tape, it is generally more flexible in the splay bending than in the bending of the broad face. Actin binding sites in alpha zones show local rigidity minima. Broken core regions due to acidic residues at the hydrophobic face such as the Asp137 and the Glu218 are found to be the most labile with moduli for splay and broad face bending as 70 nm and 116 nm respectively. Such variation in flexibility could be relevant to the tropomyosin function, especially for moving across the non-uniform surface of F-actin to regulate myosin binding.

  20. Modulation of elasticity in functionally distinct domains of the tropomyosin coiled-coil

    PubMed Central

    Lakkaraju, Sirish Kaushik; Hwang, Wonmuk

    2009-01-01

    Alpha-helical coiled-coils are common protein structural motifs. Whereas vast information is available regarding their structure, folding, and stability, far less is known about their elastic properties, even though they play mechanical roles in many cases such as tropomyosin in muscle contraction or neck stalks of kinesin or myosin motor proteins. Using computer simulations, we characterized elastic properties of coiled-coils, either globally or locally. Global bending stiffness of standard leucine zipper coiled-coils was calculated using normal mode analysis. Mutations in hydrophobic residues involved in the knob-into-hole interface between the two α-helices affect elasticity significantly, whereas charged side chains forming inter-helical salt bridges do not. This suggests that coiled-coils with less regular heptad periodicity may have regional variations in flexibility. We show this by the flexibility map of tropomyosin, which was constructed by a local fluctuation analysis. Overall, flexibility varies by more than twofold and increases towards the C-terminal region of the molecule. Describing the coiled-coil as a twisted tape, it is generally more flexible in the splay bending than in the bending of the broad face. Actin binding sites in α zones show local rigidity minima. Broken core regions due to acidic residues at the hydrophobic face such as the Asp137 and the Glu218 are found to be the most labile with moduli for splay and broad face bending as 70 nm and 116 nm respectively. Such variation in flexibility could be relevant to the tropomyosin function, especially for moving across the non-uniform surface of F-actin to regulate myosin binding. PMID:19830262

  1. The Whole Elephant: A Synoptic View of Liquid Rope Coiling

    NASA Astrophysics Data System (ADS)

    Ribe, Neil

    2016-11-01

    Liquid rope coiling is the instability that occurs when e.g. a thin stream of honey is poured onto toast. While we now have a fine-grained understanding of each of the four principal coiling modes (viscous, gravitational, inertio-gravitational and inertial), we still lack a global view of how the modes cohere to form a larger whole. Using a numerical continuation procedure, I determine how the dimensionless coiling frequency depends on the dimensionless fall height and flow rate, for several values of the dimensionless nozzle diameter. Starting with the onset of coiling, I propose a purely geometrical definition of the critical surface between coiling and no coiling as the locus of points where the radius a1 of the rope at the contact point is just equal to the coil radius R. Coiling with a1 > R is impossible because the rope would intersect itself. I characterize the asymptotic limits of the critical surface as well as the structure of the supercritical volume inside that surface. The procedure reveals a new mode of coiling onset that has not yet been identified.

  2. Current COIL research in Samara

    NASA Astrophysics Data System (ADS)

    Nikolayev, V. D.

    1996-02-01

    Development of the high pressure singlet oxygen generator (SOG) is a very important aspect for chemical oxygen-iodine laser (COIL). Increasing of oxygen pressure up to 30 torr and more at conserving high O2(1(Delta) ) yield and maintaining BHP temperature at minus (10 divided by 20) degrees Celsius permits us to decrease ration [H2O]/[O2] to 5% and less. In this case COIL can operate successfully without a water vapor trap. With raising the total pressure Reynolds number increases too, diminishing boundary layers in supersonic nozzles and improving pressure recovery. The weight and dimensions of the SOG and laser become reduced for the same gas flow rate. For solving these problems the jet SOG has been suggested and developed in Lebedev Physical Institute, Samara Branch. The advantages of the jet SOG consist of the following: (1) Large and controlled specific surface of contact liquid-gas provides for high mass transfer efficiency. (2) High jets velocity guarantees fast basic hydrogen peroxide (BHP) surface renovation. (3) High gas velocity in the reaction zone diminishes O2(1(Delta) ) quenching. (4) Efficient gas-liquid heat exchange eliminates the gas heating and generation water vapor due O2(1(Delta) ) quenching. (5) Counterflowing design of the jet SOG produces the best conditions for self-cleaning gas flow of droplets in the reaction zone and gives the possibility of COIL operation without droplets separator. High pressure jet SOG has some features connected with intrachannel jet formation, free space jets reconstruction, interaction jets ensemble with counter moving gas flow and drag part of gas by jets, disintegrating jets, generation and separation of droplets, heat effects, surface renovation, impoverishment BHP surface by HO2- ions, moving solution film on the reaction zone walls, etc. In this communication our current understanding of the major processes in the jet SOG is set forth. The complex gas and hydrodynamic processes with heat and mass transfer

  3. Coiled coils and SAH domains in cytoskeletal molecular motors.

    PubMed

    Peckham, Michelle

    2011-10-01

    Cytoskeletal motors include myosins, kinesins and dyneins. Myosins move along tracks of actin filaments, whereas kinesins and dyneins move along microtubules. Many of these motors are involved in trafficking cargo in cells. However, myosins are mostly monomeric, whereas kinesins are mostly dimeric, owing to the presence of a coiled coil. Some myosins (myosins 6, 7 and 10) contain an SAH (single α-helical) domain, which was originally thought to be a coiled coil. These myosins are now known to be monomers, not dimers. The differences between SAH domains and coiled coils are described and the potential roles of SAH domains in molecular motors are discussed.

  4. Structural Determinants of Oligomerization of the Aquaporin-4 Channel.

    PubMed

    Kitchen, Philip; Conner, Matthew T; Bill, Roslyn M; Conner, Alex C

    2016-03-25

    The aquaporin (AQP) family of integral membrane protein channels mediate cellular water and solute flow. Although qualitative and quantitative differences in channel permeability, selectivity, subcellular localization, and trafficking responses have been observed for different members of the AQP family, the signature homotetrameric quaternary structure is conserved. Using a variety of biophysical techniques, we show that mutations to an intracellular loop (loop D) of human AQP4 reduce oligomerization. Non-tetrameric AQP4 mutants are unable to relocalize to the plasma membrane in response to changes in extracellular tonicity, despite equivalent constitutive surface expression levels and water permeability to wild-type AQP4. A network of AQP4 loop D hydrogen bonding interactions, identified using molecular dynamics simulations and based on a comparative mutagenic analysis of AQPs 1, 3, and 4, suggest that loop D interactions may provide a general structural framework for tetrameric assembly within the AQP family.

  5. Coiled tubing drilling requires economic and technical analyses

    SciTech Connect

    Gary, S.C. )

    1995-02-20

    Field experience has proven that coiled tubing drilling is a technical and economic option on some wells; however, coiled tubing drilling is not the solution to every drilling prospect or production-enhancement job. To determine if coiled tubing drilling is viable, the geographic, technical, and economic aspects of each project must be considered in detail. Generally, with some limitations, coiled tubing drilling is feasible primarily when jointed pipe cannot be used effectively. Also, coiled tubing drilling may be more appropriate because of some special well site requirements, such as environmental regulations requiring less surface disturbance. The paper discusses technical considerations which need to be considered, economic feasibility, limitations of well types (new shallow wells, conventional reentry, through-tubing reentry, and underbalanced drilling), and outlook for further growth in the coiled tubing drilling industry.

  6. Correction coil cable

    DOEpatents

    Wang, Sou-Tien

    1994-11-01

    A wire cable assembly (10, 310) adapted for the winding of electrical coils is taught. A primary intended use is for use in particle tube assemblies (532) for the superconducting super collider. The correction coil cables (10, 310) have wires (14, 314) collected in wire arrays (12, 312) with a center rib (16, 316) sandwiched therebetween to form a core assembly (18, 318 ). The core assembly (18, 318) is surrounded by an assembly housing (20, 320) having an inner spiral wrap (22, 322) and a counter wound outer spiral wrap (24, 324). An alternate embodiment (410) of the invention is rolled into a keystoned shape to improve radial alignment of the correction coil cable (410) on a particle tube (733) in a particle tube assembly (732).

  7. Gain-of-function mutation in TASK-4 channels and severe cardiac conduction disorder.

    PubMed

    Friedrich, Corinna; Rinné, Susanne; Zumhagen, Sven; Kiper, Aytug K; Silbernagel, Nicole; Netter, Michael F; Stallmeyer, Birgit; Schulze-Bahr, Eric; Decher, Niels

    2014-07-01

    Analyzing a patient with progressive and severe cardiac conduction disorder combined with idiopathic ventricular fibrillation (IVF), we identified a splice site mutation in the sodium channel gene SCN5A. Due to the severe phenotype, we performed whole-exome sequencing (WES) and identified an additional mutation in the KCNK17 gene encoding the K2P potassium channel TASK-4. The heterozygous change (c.262G>A) resulted in the p.Gly88Arg mutation in the first extracellular pore loop. Mutant TASK-4 channels generated threefold increased currents, while surface expression was unchanged, indicating enhanced conductivity. When co-expressed with wild-type channels, the gain-of-function by G88R was conferred in a dominant-active manner. We demonstrate that KCNK17 is strongly expressed in human Purkinje cells and that overexpression of G88R leads to a hyperpolarization and strong slowing of the upstroke velocity of spontaneously beating HL-1 cells. Thus, we propose that a gain-of-function by TASK-4 in the conduction system might aggravate slowed conductivity by the loss of sodium channel function. Moreover, WES supports a second hit-hypothesis in severe arrhythmia cases and identified KCNK17 as a novel arrhythmia gene.

  8. Gain-of-function mutation in TASK-4 channels and severe cardiac conduction disorder

    PubMed Central

    Friedrich, Corinna; Rinné, Susanne; Zumhagen, Sven; Kiper, Aytug K; Silbernagel, Nicole; Netter, Michael F; Stallmeyer, Birgit; Schulze-Bahr, Eric; Decher, Niels

    2014-01-01

    Analyzing a patient with progressive and severe cardiac conduction disorder combined with idiopathic ventricular fibrillation (IVF), we identified a splice site mutation in the sodium channel gene SCN5A. Due to the severe phenotype, we performed whole-exome sequencing (WES) and identified an additional mutation in the KCNK17 gene encoding the K2P potassium channel TASK-4. The heterozygous change (c.262G>A) resulted in the p.Gly88Arg mutation in the first extracellular pore loop. Mutant TASK-4 channels generated threefold increased currents, while surface expression was unchanged, indicating enhanced conductivity. When co-expressed with wild-type channels, the gain-of-function by G88R was conferred in a dominant-active manner. We demonstrate that KCNK17 is strongly expressed in human Purkinje cells and that overexpression of G88R leads to a hyperpolarization and strong slowing of the upstroke velocity of spontaneously beating HL-1 cells. Thus, we propose that a gain-of-function by TASK-4 in the conduction system might aggravate slowed conductivity by the loss of sodium channel function. Moreover, WES supports a second hit-hypothesis in severe arrhythmia cases and identified KCNK17 as a novel arrhythmia gene. PMID:24972929

  9. TESLA Coil Research

    DTIC Science & Technology

    1992-05-01

    Sloan’s work was actually predated by the earlier work of Nikola Tesla . Sloan mistakenly identified " Tesla Coils" as lumped tuned resonators. The...Lefvw WsnJ L REPORT o]i 3. REPRT TYPE AND OATES COVEIRD May 1992 Special/Aug 1992 - May 1992 Z TITLE AND 5U§nUT S. FUNDING NUMIHRS Tesla Coil Research...STATEMENT 1211. ’ISTRIUUTION COOD Approved for public release; dis~ribution is unlimited 13. ABSTRACT (Masrmum 200 worw) High repetition rate Tesla

  10. Meiosis specific coiled-coil proteins in Shizosaccharomyces pombe.

    PubMed

    Ohtaka, Ayami; Saito, Takamune T; Okuzaki, Daisuke; Nojima, Hiroshi

    2007-05-18

    Many meiosis-specific proteins in Schizosaccharomyces pombe contain coiled-coil motifs which play essential roles for meiotic progression. For example, the coiled-coil motifs present in Meu13 and Mcp7 are required for their function as a putative recombinase cofactor complex during meiotic recombination. Mcp6/Hrs1 and Mcp5/Num1 control horsetail chromosome movement by astral microtubule organization and anchoring dynein respectively. Dhc1 and Ssm4 are also required for horsetail chromosome movement. It is clear from these examples that the coiled-coil motif in these proteins plays an important role during the progression of cells through meiosis. However, there are still many unanswered questions on how these proteins operate. In this paper, we briefly review recent studies on the meiotic coiled-coil proteins in Sz. pombe.

  11. Meiosis specific coiled-coil proteins in Shizosaccharomyces pombe

    PubMed Central

    Ohtaka, Ayami; Saito, Takamune T; Okuzaki, Daisuke; Nojima, Hiroshi

    2007-01-01

    Many meiosis-specific proteins in Schizosaccharomyces pombe contain coiled-coil motifs which play essential roles for meiotic progression. For example, the coiled-coil motifs present in Meu13 and Mcp7 are required for their function as a putative recombinase cofactor complex during meiotic recombination. Mcp6/Hrs1 and Mcp5/Num1 control horsetail chromosome movement by astral microtubule organization and anchoring dynein respectively. Dhc1 and Ssm4 are also required for horsetail chromosome movement. It is clear from these examples that the coiled-coil motif in these proteins plays an important role during the progression of cells through meiosis. However, there are still many unanswered questions on how these proteins operate. In this paper, we briefly review recent studies on the meiotic coiled-coil proteins in Sz. pombe. PMID:17509158

  12. A coiled-coil interaction mediates cauliflower mosaic virus cell-to-cell movement

    NASA Astrophysics Data System (ADS)

    Stavolone, Livia; Villani, Maria Elena; Leclerc, Denis; Hohn, Thomas

    2005-04-01

    The function of the virion-associated protein (VAP) of cauliflower mosaic virus (CaMV) has long been only poorly understood. VAP is associated with the virion but is dispensable for virus morphogenesis and replication. It mediates virus transmission by aphids through simultaneous interaction with both the aphid transmission factor and the virion. However, although insect transmission is not fundamental to CaMV survival, VAP is indispensable for spreading the virus infection within the host plant. We used a GST pull-down technique to demonstrate that VAP interacts with the viral movement protein through coiled-coil domains and surface plasmon resonance to measure the interaction kinetics. We mapped the movement protein coiled-coil to the C terminus of the protein and proved that it self-assembles as a trimer. Immunogold labeling/electron microscopy revealed that the VAP and viral movement protein colocalize on CaMV particles within plasmodesmata. These results highlight the multifunctional potential of the VAP protein conferred by its efficient coiled-coil interaction system and show a plant virus possessing a surface-exposed protein (VAP) mediating viral entry into host cells. movement protein | virion-associated protein | Biacore

  13. Flexible coiled spline securely joins mating cylinders

    NASA Technical Reports Server (NTRS)

    Coppernol, R. W.

    1966-01-01

    Mating cylindrical members are joined by spline to form an integral structure. The spline is made of tightly coiled, high tensile-strength steel spiral wire that fits a groove between the mating members. It provides a continuous bearing surface for axial thrust between the members.

  14. Tool Removes Coil-Spring Thread Inserts

    NASA Technical Reports Server (NTRS)

    Collins, Gerald J., Jr.; Swenson, Gary J.; Mcclellan, J. Scott

    1991-01-01

    Tool removes coil-spring thread inserts from threaded holes. Threads into hole, pries insert loose, grips insert, then pulls insert to thread it out of hole. Effects essentially reverse of insertion process to ease removal and avoid further damage to threaded inner surface of hole.

  15. An orientable search coil

    NASA Astrophysics Data System (ADS)

    Holt, P. J.; Poblocki, M.

    2017-01-01

    We provide a design for a low cost orientable search coil that can be used to investigate the variation of magnetic flux with angle. This experiment is one of the required practical activities in the current A level physics specification for the AQA examination board in the UK. We demonstrate its performance and suggest other suitable investigations that can be undertaken.

  16. Imprinted Clay Coil Vessels

    ERIC Educational Resources Information Center

    Lohr, Tresa Rae

    2006-01-01

    The author teaches clay vessel construction in the fifth grade, and it is amazing what can be accomplished in one forty-five minute period when the expectations are clarified in the initial lesson. The author introduces clay coil vessels with a discussion of the sources of clay and how clay relates to fifth-grade science curriculum concepts such…

  17. Improved Coil for Hydrogen Dissociators

    NASA Technical Reports Server (NTRS)

    Vessot, R.

    1984-01-01

    Flat coil has rigid printed circuit substrate. New coil structure minimizes RF electric field near glass walls of plasma vessel; therefore reduces direct electron bombardment of glass. Design lends itself well to high production and standardized dimensions.

  18. Pulse Test of Coil Insulation

    NASA Technical Reports Server (NTRS)

    Kroy, Ralph E.

    1987-01-01

    Waveform of back-electromotive force reveals defects. Simple pulse test reveals defects in inductor coils. Devised for use on servovalve solenoid coils on Space Shuttle, test also applicable to transformer windings, chokes, relays, and the like.

  19. Bioaerosol deposition on an air-conditioning cooling coil

    NASA Astrophysics Data System (ADS)

    Wu, Yan; Chen, Ailu; Luhung, Irvan; Gall, Elliott T.; Cao, Qingliang; Chang, Victor Wei-Chung; Nazaroff, William W.

    2016-11-01

    This study is concerned with the role of a fin-and-tube heat exchanger in modifying microbial indoor air quality. Specifically, depositional losses of ambient bioaerosols and particles onto dry (not cooled) and wet (cool) coil surfaces were measured for different airspeeds passing through the test coil. Total, bacterial and fungal DNA concentrations in condensate water produced by a wet coil were also quantified by means of fluorescent dsDNA-binding dye and qPCR assays. Results revealed that the deposition of bioaerosols and total particles is substantial on coil surfaces, especially when wet and cool. The average deposition fraction was 0.14 for total DNA, 0.18 for bacterial DNA and 0.22 for fungal DNA on the dry coil, increasing to 0.51 for total DNA, 0.50 for bacterial DNA and 0.68 for fungal DNA on the wet coil. Overall, as expected, deposition fractions increased with increasing particle size and increasing airspeed. Deposited DNA was removed from the cooling coil surfaces through the flow of condensing water at a rate comparable to the rate of direct deposition from air. A downward trend of bacterial and fungal DNA measured in condensate water over time provides suggestive evidence of biological growth on heat exchangers during nonoperational times of a ventilation system. This investigation provides new information about bioaerosol deposition onto a conventional fin-and-tube cooling coil, a potentially important factor influencing indoor exposure to microbial aerosols in air-conditioned buildings.

  20. Force modulated conductance of artificial coiled-coil protein monolayers.

    PubMed

    Atanassov, Alexander; Hendler, Ziv; Berkovich, Inbal; Ashkenasy, Gonen; Ashkenasy, Nurit

    2013-01-01

    Studies of charge transport through proteins bridged between two electrodes have been the subject of intense research in recent years. However, the complex structure of proteins makes it difficult to elucidate transport mechanisms, and the use of simple peptide oligomers may be an over simplified model of the proteins. To bridge this structural gap, we present here studies of charge transport through artificial parallel coiled-coil proteins conducted in dry environment. Protein monolayers uniaxially oriented at an angle of ∼ 30° with respect to the surface normal were prepared. Current voltage measurements, obtained using conductive-probe atomic force microscopy, revealed the mechano-electronic behavior of the protein films. It was found that the low voltage conductance of the protein monolayer increases linearly with applied force, mainly due to increase in the tip contact area. Negligible compression of the films for loads below 26 nN allowed estimating a tunneling attenuation factor, β(0) , of 0.5-0.6 Å(-1) , which is akin to charge transfer by tunneling mechanism, despite the comparably large charge transport distance. These studies show that mechano-electronic behavior of proteins can shed light on their complex charge transport mechanisms, and on how these mechanisms depend on the detailed structure of the proteins. Such studies may provide insightful information on charge transfer in biological systems.

  1. Synthesis, characterisation and applications of coiled carbon nanotubes.

    PubMed

    Hanus, Monica J; Harris, Andrew T

    2010-04-01

    Coiled carbon nanotubes are helical carbon structures formed when heptagonal and pentagonal rings are inserted into the hexagonal backbone of a 'straight' nanotube. Coiled carbon nanotubes have been reported with both regular and irregular helical structures. In this work the structure, growth mechanism(s), synthesis, properties and potential applications of coiled carbon nanotubes are reviewed. Published data suggests that coiled carbon nanotube synthesis occurs due to nonuniform extrusion of carbon from a catalyst surface. To date, coiled carbon nanotubes have been synthesised using catalyst modification techniques including: (i) the addition of S or P containing compounds during synthesis; (ii) the use of binary or ternary metal catalysts; (iii) the use of microwaves to create a local temperature gradient around individual catalyst particles and; (iv) the use of pH control during catalyst preparation. In most instances coiled carbon nanotubes are produced as a by-product; high yield and/or large-scale synthesis of coiled carbon nanotubes remains problematic. The qualitative analysis of coiled carbon nanotubes is currently hindered by the absence of specific characterisation data in the literature, e.g., oxidation profiles measured by thermogravimetric analysis and Raman spectra of pure coiled carbon nanotube samples.

  2. Coiled tubing operations and services

    SciTech Connect

    Jaworsky, A.S. II )

    1991-11-01

    Coiled tubing offers many advantages over conventional jointed tubing used for drilling in oil fields, including time savings, pumping flexibility, fluid placement, reduced formation damage and safety. The article gives an overview of coiled tubing history and development. Operating concepts are explained, along with descriptions of the major equipment and components associated with coiled tubing use in the oil field today.

  3. Wet Winding Improves Coil Encapsulation

    NASA Technical Reports Server (NTRS)

    Hill, A. J.

    1987-01-01

    Wet-winding process encapsulates electrical coils more uniformily than conventional processes. Process requires no vacuum pump and adapts easily to existing winding machines. Encapsulant applied to each layer of wire as soon as added to coil. Wet-winding process eliminates voids, giving more uniformly encapsulated coil.

  4. Modular coils: a promising toroidal-reactor-coil system

    SciTech Connect

    Chu, T.K.; Furth, H.P.; Johnson, J.L.; Ludescher, C.; Weimer, K.E.

    1981-04-01

    The concept of modular coils originated from a need to find reactor-relevant stellarator windings, but its usefulness can be extended to provide an externally applied, additional rotational transform in tokamaks. Considerations of (1) basic principles of modular coils, (2) types of coils, (3) types of configurations (general, helically symmetric, helically asymmetric, with magnetic well, with magnetic hill), (4) types of rotational transform profile, and (5) structure and origin of ripples are given. These results show that modular coils can offer a wide range of vacuum magnetic field configurations, some of which cannot be obtained with the classical stellarator or torsatron coil configuration.

  5. Hydrocephalus: the role of cerebral aquaporin-4 channels and computational modeling considerations of cerebrospinal fluid.

    PubMed

    Desai, Bhargav; Hsu, Ying; Schneller, Benjamin; Hobbs, Jonathan G; Mehta, Ankit I; Linninger, Andreas

    2016-09-01

    Aquaporin-4 (AQP4) channels play an important role in brain water homeostasis. Water transport across plasma membranes has a critical role in brain water exchange of the normal and the diseased brain. AQP4 channels are implicated in the pathophysiology of hydrocephalus, a disease of water imbalance that leads to CSF accumulation in the ventricular system. Many molecular aspects of fluid exchange during hydrocephalus have yet to be firmly elucidated, but review of the literature suggests that modulation of AQP4 channel activity is a potentially attractive future pharmaceutical therapy. Drug therapy targeting AQP channels may enable control over water exchange to remove excess CSF through a molecular intervention instead of by mechanical shunting. This article is a review of a vast body of literature on the current understanding of AQP4 channels in relation to hydrocephalus, details regarding molecular aspects of AQP4 channels, possible drug development strategies, and limitations. Advances in medical imaging and computational modeling of CSF dynamics in the setting of hydrocephalus are summarized. Algorithmic developments in computational modeling continue to deepen the understanding of the hydrocephalus disease process and display promising potential benefit as a tool for physicians to evaluate patients with hydrocephalus.

  6. Performance correlation between YBa2Cu3O7-δ coils and short samples for coil technology development

    NASA Astrophysics Data System (ADS)

    Wang, X.; Dietderich, D. R.; Godeke, A.; Gourlay, S. A.; Marchevsky, M.; Prestemon, S. O.; Sabbi, G. L.

    2016-06-01

    A robust fabrication technology is critical to achieve the high performance in YBa2Cu3O{}7-δ (YBCO) coils as the critical current of the brittle YBCO layer is subject to the strain-induced degradation during coil fabrication. The expected current-carrying capability of the magnet and its temperature dependence are two key inputs to the coil technology development. However, the expected magnet performance is not straightforward to determine because the short-sample critical current depends on both the amplitude and orientation of the applied magnetic field with respect to the broad surface of the tape-form conductor. In this paper, we present an approach to calculate the self-field performance limit for YBCO racetrack coils at 77 and 4.2 K. Critical current of short YBCO samples was measured as a function of the applied field perpendicular to the conductor surface from 0 to 15 T. This field direction limited the conductor critical current. Two double-layer racetrack coils, one with three turns and the other with 10 turns, were wound and tested at 77 and 4.2 K. The test coils reached at least 80% of the expected critical current. The ratio between the coil critical currents at 77 and 4.2 K agreed well with the calculation. We conclude that the presented approach can determine the performance limit in YBCO racetrack coils based on the short-sample critical current and provide a useful guideline for assessing the coil performance and fabrication technology. The correlation of the coil critical current between 77 K and 4.2 K was also observed, allowing the 77 K test to be a cost-effective tool for the development of coil technology.

  7. A real-time screening assay for GIRK1/4 channel blockers.

    PubMed

    Walsh, Kenneth B

    2010-12-01

    The cardiac acetylcholine-activated K(+) channel (I(K,Ach)) represents a novel target for drug therapy in the treatment of atrial fibrillation (AF). This channel is a member of the G-protein-coupled inward rectifier K(+) (GIRK) channel superfamily and is composed of the GIRK1/4 (Kir3.1 and Kir3.4) subunits. The goal of this study was to develop a cell-based screening assay for identifying new blockers of the GIRK1/4 channel. The mouse atrial HL-1 cell line, expressing the GIRK1/4 channel, was plated in 96-well plate format, loaded with the fluorescent membrane potential-sensitive dye bis-(1,3-dibutylbarbituric acid) trimethine oxonol (DiBAC(4)(3)) and measured using a fluorescent imaging plate reader (FLIPR). Application of the muscarinic agonist carbachol to the cells caused a rapid, time-dependent decrease in the fluorescent signal, indicative of K(+) efflux through the GIRK1/4 channel (carbachol vs. control solution, Z' factor = 0.5-0.6). The GIRK1/4 channel fluorescent signal was blocked by BaCl(2) and enhanced by increasing the driving force for K(+) across the cell membrane. To test the utility of the assay for screening GIRK1/4 channel blockers, cells were treated with a small compound library of Na(+) and K(+) channel modulators. Analogues of amiloride and propafenone were identified as channel blockers at concentrations less than 1 µM. Thus, the GIRK1/4 channel assay may be used in the development of new and selective agents for treating AF.

  8. Thermophoresis of polymers: nondraining vs draining coil.

    PubMed

    Morozov, Konstantin I; Köhler, Werner

    2014-06-10

    Present theories for the thermophoretic mobility of polymers in dilute solution without long-ranged electrostatic interaction are based on a draining coil model with short-ranged segment-solvent interaction. We show that the characteristic thermophoretic interaction decays as r(-2) with the distance from the chain segment, which is of much longer range than the underlying rapidly decaying binary van der Waals interaction (∝ r(-6)). As a consequence, thermophoresis on the monomer level is governed by volume forces, resulting in hydrodynamic coupling between the chain segments. The inner parts of the nondraining coil do not actively participate in thermophoresis. The flow lines penetrate only into a thin surface layer of the coil and cause tangential stresses along the surface of the entire coil, not the individual segments. This model is motivated by recent experimental findings for thermoresponsive polymers and core-shell particles, and it explains the well-known molar mass independent thermophoretic mobility of polymers in dilute solution.

  9. New head gradient coil design and construction techniques

    PubMed Central

    Handler, William B; Harris, Chad T; Scholl, Timothy J; Parker, Dennis L; Goodrich, K Craig; Dalrymple, Brian; Van Sass, Frank; Chronik, Blaine A

    2013-01-01

    Purpose To design and build a head insert gradient coil to use in conjunction with body gradients for superior imaging. Materials and Methods The use of the Boundary Element Method to solve for a gradient coil wire pattern on an arbitrary surface has allowed us to incorporate engineering changes into the electromagnetic design of a gradient coil directly. Improved wire pattern design has been combined with robust manufacturing techniques and novel cooling methods. Results The finished coil had an efficiency of 0.15 mT/m/A in all three axes and allowed the imaging region to extend across the entire head and upper part of the neck. Conclusion The ability to adapt your electromagnetic design to necessary changes from an engineering perspective leads to superior coil performance. PMID:24123485

  10. Coiled tubing; Operations and services

    SciTech Connect

    Brown, P.T.; Wimberly, R.D.

    1992-10-01

    Oil and gas wells that flow on initial completion eventually reach a condition of liquid loading that kills the wells. This results form declining reservoir pressure, decreased gas volume (velocity), increased water production and other factors that cause liquids to accumulate at the bottom of the well and exert back pressure on the formation. This restricts or in some cases prevents fluid entry into the wellbore form the formation. Flowing production can be restored or increased by reducing surface backpressure, well bore stimulation, pressure maintenance or by installing a string of smaller diameter tubing. This paper reports on installation (hanging off) of a concentric string of coiled tubing inside existing production tubing which is an economically viable, safe, convenient and effective alterative for returning some of these liquid loaded )logged-up) wells to flowing status.

  11. Natural convection from vertical helical coiled tubes in air

    SciTech Connect

    Ali, M.E.

    1999-07-01

    Helically coiled tubes are used in many engineering applications, such as heating, refrigerating and HVAC systems. They are used also in steam generator and condenser design in power plants because of their large surface area per unit volume. In spite of their widespread use, there is very little information available in the literature on natural convection from such coils. Two experimental investigation have been reported on steady state laminar and transition natural convection from the outer surface of vertically oriented helical coiled tubes in air. Four coils at constant heat flux boundary condition have been used with coil diameter to tube diameter ratio of 16.45 and 23.94. Six more coils have been used at variable surface temperature boundary condition with coil diameter to tube diameter ratio 19.923, 15.904, and 12.798. Local average heat transfer coefficients are obtained for laminar and transition natural convection. The data are correlated with Rayleigh number using the tube diameter as a characteristic length. It has been found that the Nusselt number decreases as Rayleigh number increases for constant heat flux. Transition to turbulent natural convection regime has obtained at a critical Rayleigh number of about 5,000 and it characterizes by a waveform like relation between Nusselt number and Rayleigh number.

  12. An improved asymmetric gradient coil design for high-resolution MRI head imaging.

    PubMed

    Tang, Fangfang; Liu, Feng; Freschi, Fabio; Li, Yu; Repetto, Maurizio; Giaccone, Luca; Wang, Yaohui; Crozier, Stuart

    2016-12-21

    For head magnetic resonance imaging, local gradient coils are often used to achieve high solution images. To accommodate the human head and shoulder, the head gradient coils are usually designed in an asymmetric configuration, allowing the region-of-uniformity (ROU) close to the coil's patient end. However, the asymmetric configuration leads to technical difficulties in maintaining a high gradient performance for the insertable head coil with very limited space. In this work, we present a practical design configuration of an asymmetric insertable gradient head coil offering an improved performance. In the proposed design, at the patient end, the primary and secondary coils are connected using an additional radial surface, thus allowing the coil conductors distributed on the flange to ensure an improvement in the coil performance. At the service end, the primary and shielding coils are not connected, to permit access to shim trays, cooling system piping, cabling, and so on. The new designs are compared with conventional coil configurations and the simulation results show that, with a similar field quality in the ROU, the proposed coil pattern has improved construction characteristics (open service end, well-distributed wire pattern) and offers a better coil performance (lower inductance, higher efficiency, etc) than conventional head coil configurations.

  13. Formulation for a practical implementation of electromagnetic induction coils optimized using stream functions

    NASA Astrophysics Data System (ADS)

    Reed, Mark A.; Scott, Waymond R.

    2016-05-01

    Continuous-wave (CW) electromagnetic induction (EMI) systems used for subsurface sensing typically employ separate transmit and receive coils placed in close proximity. The closeness of the coils is desirable for both packaging and object pinpointing; however, the coils must have as little mutual coupling as possible. Otherwise, the signal from the transmit coil will couple into the receive coil, making target detection difficult or impossible. Additionally, mineralized soil can be a significant problem when attempting to detect small amounts of metal because the soil effectively couples the transmit and receive coils. Optimization of wire coils to improve their performance is difficult but can be made possible through a stream-function representation and the use of partially convex forms. Examples of such methods have been presented previously, but these methods did not account for certain practical issues with coil implementation. In this paper, the power constraint introduced into the optimization routine is modified so that it does not penalize areas of high current. It does this by representing the coils as plates carrying surface currents and adjusting the sheet resistance to be inversely proportional to the current, which is a good approximation for a wire-wound coil. Example coils are then optimized for minimum mutual coupling, maximum sensitivity, and minimum soil response at a given height with both the earlier, constant sheet resistance and the new representation. The two sets of coils are compared both to each other and other common coil types to show the method's viability.

  14. KCNN4 channels participate in the EMT induced by PRL-3 in colorectal cancer.

    PubMed

    Lai, Wei; Liu, Lu; Zeng, Yujie; Wu, Heng; Xu, Heyang; Chen, Shuang; Chu, Zhonghua

    2013-01-01

    Studies have shown that phosphatase of regenerating liver-3 (PRL-3) promotes the invasion, migration, and metastasis of human tumor cells by facilitating an epithelial-mesenchymal transition (EMT). However, the mechanism by which PRL-3 induces tumor cell EMT is unknown. Our previous research revealed that PRL-3 promotes LoVo cell proliferation by up-regulating KCNN4 channels. In the current study, we explored the mechanism by which PRL-3 mediates EMT. We demonstrated that PRL-3 induced the expression of KCNN4 channels, leading to EMT and the down-regulation of E-cadherin. Further studies revealed that KCNN4 channels increased intracellular calcium levels and activated components of cell signaling downstream of calcium, including CaM-kinase II and glycogen synthase kinase-3 beta (GSK-3 beta), which increased Snail expression. Inhibiting KCNN4 with siRNA and TRAM-34, a specific inhibitor, restored E-cadherin expression and inhibited Snail expression. These results implicated the up-regulation of KCNN4 channels in the PRL-3-mediated induction of EMT and promotion of cancer metastasis.

  15. [Kv3.4 channel is involved in rat pulmonary vasoconstriction induced by 15-hydroxyeicosatetraenoic acid].

    PubMed

    Li, Qian; Bi, Hai-Rong; Zhang, Rong; Zhu, Da-Ling

    2006-02-25

    We have reported that hypoxia increases the activation of 15-lipoxygenase (15-LO), which converts arachidonic acid (AA) into 15-hydroxyeicosatetraenoic acid (15-HETE) in small pulmonary arteries (PAs). Through inhibition of Kv channels, 15-HETE causes more robust concentration-dependent contraction of PA rings from the hypoxic compared to the normoxic controls. However, the subtypes of Kv channels inhibited by 15-HETE are incompletely understood. The aim of the present study was to identify the contribution of Kv3.4 channel in the process of pulmonary vasoconstriction induced by 15-HETE using the tension studies of PA rings from rat with Kv3.4 channel blocker in tissue bath; to explore the role of vascular endothelium in15-HETE-induced pulmonary vasoconstriction through denuded endothelia of PA rings; and to define the downregulation of 15-HETE on the expression of Kv3.4 channel in cultured pulmonary artery smooth muscle cells (PASMCs) with RT-PCR and Western blot. In the present study, healthy Wistar rats were divided randomly into two groups: Group A with normal oxygen supply and group B with hypoxia. Six days later, the rats were killed. Pulmonary artery rings were prepared for organ bath experiments. Firstly, different concentrations of 15-HETE (10~1 000 nmol/L) were added to the Krebs solution. The isometric tension was recorded using a four-channel force-displacement transducer. Then Kv3.4 channel blocker, 100 nmol/L BDS-I, was added, followed by adding 1 mumol/L 15-HETE, and the isometric tension was recorded. Furthermore, RT-PCR and Western blot were employed to identify the influence of 15-HETE on the expression of Kv3.4 channel in cultured rat PASMCs.The results showed the PA tension was significantly increased both in groups A and B by 15-HETE in a concentration-dependent manner (P<0.05), especially in group B (P<0.05 compared to control); denuded endothelia enhanced 15-HETE concentration-related constrictions in rat PA rings; Kv3.4 channel blocker, BDS

  16. Crystal Structure of the Human Short Coiled Coil Protein and Insights into SCOC-FEZ1 Complex Formation

    PubMed Central

    Behrens, Caroline; Binotti, Beyenech; Schmidt, Carla; Robinson, Carol V.; Chua, John Jia En; Kühnel, Karin

    2013-01-01

    The short coiled coil protein (SCOC) forms a complex with fasciculation and elongation protein zeta 1 (FEZ1). This complex is involved in autophagy regulation. We determined the crystal structure of the coiled coil domain of human SCOC at 2.7 Å resolution. SCOC forms a parallel left handed coiled coil dimer. We observed two distinct dimers in the crystal structure, which shows that SCOC is conformationally flexible. This plasticity is due to the high incidence of polar and charged residues at the core a/d-heptad positions. We prepared two double mutants, where these core residues were mutated to either leucines or valines (E93V/K97L and N125L/N132V). These mutations led to a dramatic increase in stability and change of oligomerisation state. The oligomerisation state of the mutants was characterized by multi-angle laser light scattering and native mass spectrometry measurements. The E93V/K97 mutant forms a trimer and the N125L/N132V mutant is a tetramer. We further demonstrate that SCOC forms a stable homogeneous complex with the coiled coil domain of FEZ1. SCOC dimerization and the SCOC surface residue R117 are important for this interaction. PMID:24098481

  17. Evaluation of a New 1H/31P Dual-Tuned Birdcage Coil for 31P Spectroscopy

    PubMed Central

    Potter, WM; Wang, L; McCully, KK; Zhao, Q

    2013-01-01

    We introduce a new dual-tuned Hydrogen/Phosphorus (1H/31P) birdcage coil, referred to as split birdcage coil, and evaluate its performance using both simulations and magnetic resonance (MR) experiments on a 3 T MR scanner. The proposed coil simplifies the practical matters of tuning and matching, which makes the coil easily reproducible. Simulations were run with the Finite Difference in Time Domain (FDTD) method to evaluate the sensitivity and homogeneity of the magnetic field generated by the proposed 1H coils. Following simulations, MR experiments were conducted using both a phantom and human thigh to compare the proposed design with a currently available commercial dual-tuned flexible surface coil, referred to as flex surface coil, for signal to noise ratio (SNR) as well as homogeneity for the 31P coil. At regions deep within the human thigh, the split birdcage coil was able to acquire spectroscopic signal with a higher average SNR than the flex surface coil. For all regions except those close to the flex surface coil, the split birdcage coil matched or exceeded the performance of the flex surface coil. PMID:24039555

  18. Further advances in coiled-tubing drilling

    SciTech Connect

    Eide, E.; Brinkhorst, J.; Voelker, H.; Burge, P.; Ewen, R.L.

    1994-12-31

    The use of coiled tubing to drill horizontal re-entry wells has received considerable interest in the industry over the last two years. The benefit of being able to drill at balance, safely and in a controlled manner, using nitrogen to reduce down hole pressure while drilling highly depleted reservoirs, provides an advantage over conventional techniques, particularly in reducing impairment to the formation. The paper describes such a horizontal re-entry drilled in the shallow depleted water flooded reservoir Barenburg in Northern Germany. The entire program was executed with no intervention from a conventional rig or workover hoist. A special structure to be positioned over the well to support the coiled tubing injector head and to provide a work platform had to be constructed for this type of operation. A dedicated mast for lifting of pipe and down hole tools was placed on the substructure. The development of a surface controlled orienting tool and an adjustable motor provided excellent directional capabilities on a 2 3/8 in. coiled tubing. This program represents a significant extension of the capabilities of drilling with coiled tubing.

  19. Squeeze cement method using coiled tubing

    SciTech Connect

    Underdown, D.R.; Ashford, J.D.; Harrison, T.W.; Eastlack, J.K.; Blount, C.G.; Herring, G.D.

    1986-12-09

    A method is described of squeeze cementing a well wherein the well has a casing throughout the wellbore, casing cement between the casing and the wellbore of the well, perforations through the casing and the casing cement to establish fluid communication between the interior of the casing and a formation adjacent the perforations, channels in the casing cement in fluid communication with at least some of the perforations, a well tubing string in the casing extending from the surface to the proximity of the perforations, and a packer means for sealing between the tubing and the casing above the perforations. The method consists of: isolating the casing adjacent the perforations; lowering a coiled tubing down the well tubing string to a point adjacent the perforations; flowing uncontaminated squeeze cement through the coiled tubing and through the perforations into the channels; flowing a cement contaminating liquid down the coiled tubing to mix with the squeeze cement remaining in the casing; allowing the uncontaminated squeeze cement in the channels to harden; and removing the contaminated squeeze cement from the casing through the coiled tubing.

  20. Coiled tubing; Operations and services

    SciTech Connect

    Welch, J.L.; Stephens, R.K. )

    1992-09-01

    This paper reports on coiled tubing units which are used for many types of remedial well operations, including sand plugbacks, cement squeezes, fill cleanouts, underreaming, acid stimulations, and fishing. Fishing operations include removal of inflatable bridge plugs, lock mandrels stuck in profile nipples, coiled tubing, coiled tubing bottomhole assemblies (BHAs) and wireline. Recommended guidelines for selecting candidates, proper tool string configuration and operational techniques are presented here to assist coiled tubing supervisors and company representatives in the planning and implementation of efficient and effective fishing operations. Treatment of these areas are not intended to be exhaustive, but rather generally representative of common applications. Each fishing operation requires individualized analysis and planning.

  1. Discrete-coil investigations of modular stellarator configurations

    SciTech Connect

    Lilliequist, C.G.

    1985-10-01

    The existence of a vacuum magnetic well is generally accepted as a prerequisite to start-up. The special set of modular-stellarator configurations selected for the present computational investigation was derived from coefficients and equations that produced finite-beta wells in a continuous-current-sheet representation. The corresponding coils did not produce magnetic wells in a vacuum when their field configuration was investigated with a discrete-coil code. Vacuum magnetic wells have been identified through the use of this discrete-coil code in previous Heliac and stellarator studies. Therefore, these finite-beta magnetic wells could be the consequence of the continuous-current-sheet model: a conjecture that is supported by the linear scaling of the magnetic hills found in the present work as a function of the separation between the coils used. In addition to magnetic field profiles, comparisons are shown here of ripple, rotational transform, and flux-surface shapes for the discrete-coil, modular stellarators under study. Initially, each of the significant parameters affecting the shape of the control surface upon which the coils lie and the deformation of the individual coils was varied separately in search of a vacuum magnetic well in the parameter neighborhood of the successful finite-beta configuration.

  2. Triple Halo Coil: Development and Comparison with Other TMS Coils

    NASA Astrophysics Data System (ADS)

    Rastogi, Priyam; Hadimani, Ravi; Jiles, David

    Transcranial Magnetic Stimulation (TMS) is a non-invasive stimulation technique that can be used for the treatment of various neurological disorders such as Parkinson's Disease, PTSD, TBI and anxiety by regulating synaptic activity. TMS is FDA approved for the treatment of major depressive disorder. There is a critical need to develop deep TMS coils that can stimulate deeper regions of the brain without excessively stimulating the cortex in order to provide an alternative to surgical methods. We have developed a novel multi-coil configuration called ``Triple Halo Coil'' (THC) that can stimulate deep brain regions. Investigation of induced electric and magnetic field in these regions have been achieved by computer modelling. Comparison of the results due to THC configuration have been conducted with other TMS coils such as ``Halo Coil'', circular coil and ``Figure of Eight'' coil. There was an improvement of more than 15 times in the strength of magnetic field, induced by THC configuration at 10 cm below the vertex of the head when compared with the ``Figure of Eight'' coil alone. Carver Charitable Trust.

  3. Eddy-current transducer based on flat spiral coils

    SciTech Connect

    Franyuk, V.A.; Ivan'kovich, L.F.

    1988-12-01

    The article deals with the experimental investigation of flat-coil eddy current transducers with spiral windings. It is shown that it is possible to use them for detecting discontinuities on electrically conducting products with different configuration of the surface. The instrument is described. The use of crossed flat coils makes it possible effectively to detect flaws in electrically conducting products of any shape. A transducer containing crossed flat coils helps, in addition to detecting flaws, in evaluating anisotropy (magnetic and mechanical) from which conclusions as to the physicomechanical properties of the product can be drawn.

  4. A Parallel Coiled-Coil Tetramer with Offset Helices

    SciTech Connect

    Liu,J.; Deng, Y.; Zheng, Q.; Cheng, C.; Kallenbach, N.; Lu, M.

    2006-01-01

    Specific helix-helix interactions are fundamental in assembling the native state of proteins and in protein-protein interfaces. Coiled coils afford a unique model system for elucidating principles of molecular recognition between {alpha} helices. The coiled-coil fold is specified by a characteristic seven amino acid repeat containing hydrophobic residues at the first (a) and fourth (d) positions. Nonpolar side chains spaced three and four residues apart are referred to as the 3-4 hydrophobic repeat. The presence of apolar amino acids at the e or g positions (corresponding to a 3-3-1 hydrophobic repeat) can provide new possibilities for close-packing of {alpha}-helices that includes examples such as the lac repressor tetramerization domain. Here we demonstrate that an unprecedented coiled-coil interface results from replacement of three charged residues at the e positions in the dimeric GCN4 leucine zipper by nonpolar valine side chains. Equilibrium circular dichroism and analytical ultracentrifugation studies indicate that the valine-containing mutant forms a discrete {alpha}-helical tetramer with a significantly higher stability than the parent leucine-zipper molecule. The 1.35 {angstrom} resolution crystal structure of the tetramer reveals a parallel four-stranded coiled coil with a three-residue interhelical offset. The local packing geometry of the three hydrophobic positions in the tetramer conformation is completely different from that seen in classical tetrameric structures yet bears resemblance to that in three-stranded coiled coils. These studies demonstrate that distinct van der Waals interactions beyond the a and d side chains can generate a diverse set of helix-helix interfaces and three-dimensional supercoil structures.

  5. An improved asymmetric gradient coil design for high-resolution MRI head imaging

    NASA Astrophysics Data System (ADS)

    Tang, Fangfang; Liu, Feng; Freschi, Fabio; Li, Yu; Repetto, Maurizio; Giaccone, Luca; Wang, Yaohui; Crozier, Stuart

    2016-12-01

    For head magnetic resonance imaging, local gradient coils are often used to achieve high solution images. To accommodate the human head and shoulder, the head gradient coils are usually designed in an asymmetric configuration, allowing the region-of-uniformity (ROU) close to the coil’s patient end. However, the asymmetric configuration leads to technical difficulties in maintaining a high gradient performance for the insertable head coil with very limited space. In this work, we present a practical design configuration of an asymmetric insertable gradient head coil offering an improved performance. In the proposed design, at the patient end, the primary and secondary coils are connected using an additional radial surface, thus allowing the coil conductors distributed on the flange to ensure an improvement in the coil performance. At the service end, the primary and shielding coils are not connected, to permit access to shim trays, cooling system piping, cabling, and so on. The new designs are compared with conventional coil configurations and the simulation results show that, with a similar field quality in the ROU, the proposed coil pattern has improved construction characteristics (open service end, well-distributed wire pattern) and offers a better coil performance (lower inductance, higher efficiency, etc) than conventional head coil configurations.

  6. Coiled-coil destabilizing residues in the group A Streptococcus M1 protein are required for functional interaction

    PubMed Central

    Stewart, Chelsea M.; Buffalo, Cosmo Z.; Valderrama, J. Andrés; Henningham, Anna; Cole, Jason N.; Nizet, Victor; Ghosh, Partho

    2016-01-01

    The sequences of M proteins, the major surface-associated virulence factors of the widespread bacterial pathogen group A Streptococcus, are antigenically variable but have in common a strong propensity to form coiled coils. Paradoxically, these sequences are also replete with coiled-coil destabilizing residues. These features are evident in the irregular coiled-coil structure and thermal instability of M proteins. We present an explanation for this paradox through studies of the B repeats of the medically important M1 protein. The B repeats are required for interaction of M1 with fibrinogen (Fg) and consequent proinflammatory activation. The B repeats sample multiple conformations, including intrinsically disordered, dissociated, as well as two alternate coiled-coil conformations: a Fg-nonbinding register 1 and a Fg-binding register 2. Stabilization of M1 in the Fg-nonbinding register 1 resulted in attenuation of Fg binding as expected, but counterintuitively, so did stabilization in the Fg-binding register 2. Strikingly, these register-stabilized M1 proteins gained the ability to bind Fg when they were destabilized by a chaotrope. These results indicate that M1 stability is antithetical to Fg interaction and that M1 conformational dynamics, as specified by destabilizing residues, are essential for interaction. A “capture-and-collapse” model of association accounts for these observations, in which M1 captures Fg through a dynamic conformation and then collapses into a register 2-coiled coil as a result of stabilization provided by binding energy. Our results support the general conclusion that destabilizing residues are evolutionarily conserved in M proteins to enable functional interactions necessary for pathogenesis. PMID:27512043

  7. Elementary Ca2+ Signals Through Endothelial TRPV4 Channels Regulate Vascular Function

    PubMed Central

    Sonkusare, Swapnil K.; Bonev, Adrian D.; Ledoux, Jonathan; Liedtke, Wolfgang; Kotlikoff, Michael I.; Heppner, Thomas J.; Hill-Eubanks, David C.; Nelson, Mark T.

    2013-01-01

    Major features of the transcellular signaling mechanism responsible for endothelium-dependent regulation of vascular smooth muscle tone are unresolved. We identified local calcium (Ca2+) signals (“sparklets”) in the vascular endothelium of resistance arteries that represent Ca2+ influx through single TRPV4 cation channels. Gating of individual TRPV4 channels within a four-channel cluster was cooperative, with activation of as few as three channels per cell causing maximal dilation through activation of endothelial cell intermediate (IK)- and small (SK)-conductance, Ca2+-sensitive potassium (K+) channels. Endothelial-dependent muscarinic receptor signaling also acted largely through TRPV4 sparklet-mediated stimulation of IK and SK channels to promote vasodilation. These results support the concept that Ca2+ influx through single TRPV4 channels is leveraged by the amplifier effect of cooperative channel gating and the high Ca2+ sensitivity of IK and SK channels to cause vasodilation. PMID:22556255

  8. Collapse pressure of coiled tubing

    SciTech Connect

    Yang, Y.S.

    1996-09-01

    The collapse pressure is a measure of an external force required to collapse a tube in the absence of internal pressure. It is defined as the minimum pressure required to yield the tube in the absence of internal pressure. Coiled tubing is sometimes used in high-pressure wells. If the external pressure becomes too high, the coiled tubing will collapse. This could not only lead to serious well-control problems, but may result in extensive fishing operations. A reliable safety criterion of collapse pressure for the coiled tubing is needed by the coiled tubing operators. Theoretical models of collapse pressure are well developed for perfectly round coiled tubing but not for oval coiled tubing. Coiled tubing is initially manufactured with nearly perfect roundness, sometimes having a small ovality (typically {le} 0.5%). Perfectly round CT becomes oval owing to the plastic mechanical deformation of the coiled tubing as it spooled on and off the reel and over the gooseneck. As the cycling continues, the ovality usually increases. This ovality significantly decreases the collapse failure pressure as compared to perfectly round tubing. In this paper, an analytical model of collapse pressure for oval tubing under axial tension or compression is developed based on elastic instability theory and the von Mises criterion. The theoretical model shows satisfactory agreement with experimental data.

  9. COIL technology development at Boeing

    NASA Astrophysics Data System (ADS)

    Hurlock, Steve C.

    2002-05-01

    The historical COIL contributions at the McDonnell Douglas Research Laboratory, the Rocketdyne Division of Rockwell International and Boeing's Laser and Electro-Optic Systems organization are briefly described. The latter organization now contains the capabilities of the two heritage organizations. Boeing's new high pressure sealed COIL is also described.

  10. Replaceable Sleeve Protects Welder Coil

    NASA Technical Reports Server (NTRS)

    Baker, W. L.; Simpson, C., E.

    1983-01-01

    New replaceable carbon insert for deflection coil in electron-beam welder promises to decrease maintenance costs. Inserts made from materials other than carbon (not yet tried) are less expensive, thus reducing costs even further. With carbon insert, deflection coils last longer and are easier to maintain.

  11. Magnet Coil Shorted Turn Detector

    SciTech Connect

    Dinkel, J.A.; Biggs, J.E.

    1994-03-01

    The Magnet Coil Shorted Turn Detector has been developed to facilitate the location of shorted turns in magnet coils. Finding these shorted turns is necessary to determine failure modes that are a necessary step in developing future production techniques. Up to this point, coils with shorted turns had the insulation burned off without the fault having been located. This disassembly process destroyed any chance of being able to find the fault. In order to maintain a flux balance in a coupled system such as a magnet coil, the current in a shorted turn must be opposed to the incident current. If the direction of the current in each conductor can be measured relative to the incident current, then the exact location of the short can be determined. In this device, an AC voltage is applied to the magnet under test. A small hand held B-dot pickup coil monitors the magnetic field produced by current in the individual magnet conductors. The relative phase of this pickup coil voltage is compared to a reference signal derived from the input current to detect a current reversal as the B-dot pickup coil is swept over the conductors of the coil under test. This technique however, is limited to only those conductors that are accessible to the hand held probe.

  12. The Coil Method in Contemporary Ceramics

    ERIC Educational Resources Information Center

    Nigrosh, Leon I.

    1976-01-01

    For centuries coil building has been the primary method of making pottery the world over. Many classrooms still reflect this preference for symmetrical coil building. Describes coil building and what forms can be made from it. (Author/RK)

  13. Studies of the effect of ionomycin on the KCNQ4 channel expressed in Xenopus oocytes.

    PubMed

    Su, Ching-Chyuan; Li, Shuan-Yow; Yang, Jiann-Jou; Su, Mao-Chang; Lin, Min-Jon

    2006-09-15

    The effect of ionomycin on the human KCNQ4 channels expressed in Xenopus leavis oocytes was investigated. KCNQ4 channels expressed in Xenopus oocytes were measured using two-electrode voltage clamp. The activation of KCNQ4 current had slow activation kinetics and low threshold (approximately -50 mV). The expressed current of KCNQ4 showed the half-maximal activation (V(1/2)) was -17.8 mV and blocked almost completely by KCNQ4 channel blockers, linopirdine (300 microM) or bepridil (200 microM). The significant increase of KCNQ4 outward current induced by ionomycin (calcium salt) is about 1.7-fold of control current amplitude at +60 mV and shifted V(1/2) by approximately -8 mV (from -17.8 to -26.0 mV). This effect of ionomycin could be reversed by the further addition of BAPTA-AM (0.3 mM), a membrane-permeable calcium chelator. Furthermore, the increased effect of ionomycin on KCNQ4 current is abolished by pretreatment of linopirdine or bepridil. In contrast, direct cytoplasmic injection of calcium medium (up to 1 mM calcium, 50 nl) did not mimic the effect of ionomycin. In conclusion, the effect of ionomycin on enhancement of KCNQ4 current is independent of intracellular calcium mobilization and possibly acts on intramembrane hydrophobic site of KCNQ4 protein expressed in Xenopus oocytes.

  14. Note: High turn density magnetic coils with improved low pressure water cooling for use in atom optics

    NASA Astrophysics Data System (ADS)

    McKay Parry, Nicholas; Baker, Mark; Neely, Tyler; Carey, Thomas; Bell, Thomas; Rubinsztein-Dunlop, Halina

    2014-08-01

    We describe a magnetic coil design utilizing concentrically wound electro-magnetic insulating (EMI) foil (25.4 μm Kapton backing and 127 μm thick layers). The magnetic coils are easily configurable for different coil sizes, while providing large surfaces for low-pressure (0.12 bar) water cooling. The coils have turn densities of ˜5 mm-1 and achieve a maximum of 377 G at 2.1 kW driving power, measured at a distance 37.9 mm from the axial center of the coil. The coils achieve a steady-state temperature increase of 36.7°C/kW.

  15. Structural and biochemical characterizations of an intramolecular tandem coiled coil protein.

    PubMed

    Shin, Donghyuk; Kim, Gwanho; Kim, Gyuhee; Zheng, Xu; Kim, Yang-Gyun; Lee, Sangho

    2014-12-12

    Coiled coil has served as an excellent model system for studying protein folding and developing protein-based biomaterials. Most designed coiled coils function as oligomers, namely intermolecular coiled coils. However, less is known about structural and biochemical behavior of intramolecular coiled coils where coiled coil domains are covalently linked in one polypeptide. Here we prepare a protein which harbors three coiled coil domains with two short linkers, termed intramolecular tandem coiled coil (ITCC) and characterize its structural and biochemical behavior in solution. ITCC consists of three coiled coil domains whose sequences are derived from Coil-Ser and its domain swapped dimer. Modifications include positioning E (Glu) residue at "e" and K (Lys) at "g" positions throughout heptad repeats to enhance ionic interaction among its constituent coiled coil domains. Molecular modeling of ITCC suggests a compact triple helical bundle structure with the second and the third coiled coil domains forming a canonical coiled coil. ITCC exists as a mixture of monomeric and dimeric species in solution. Small-angle X-ray scattering reveals ellipsoidal molecular envelopes for both dimeric and monomeric ITCC in solution. The theoretically modeled structures of ITCC dock well into the envelopes of both species. Higher ionic strength shifts the equilibrium into monomer with apparently more compact structure while secondary structure remains unchanged. Taken together, our results suggest that our designed ITCC is predominantly monomeric structure through the enhanced ionic interactions, and its conformation is affected by the concentration of ionic species in the buffer.

  16. Coiled tubing applications for underground gas storage

    SciTech Connect

    Fowler, H.; Holcombe, D.

    1994-12-31

    Technological advances in coiled tubing (CT), CT handling equipment, and application techniques have provided new opportunities for the effective, economic use of CT for gas storage and retrieval. This paper presents a review of the CT capabilities that can be used for improving the performance of gas storage wells and discusses applications that could be performed with CT in the near future. For more than 25 years, coiled tubing has been use as an effective, economic means of performing remedial well services. In response to the demand for better horizontal drilling equipment, the strength and diameter of CT has been increased, while surface equipment and downhole tools have become more sophisticated. CT is also widely used in well servicing after initial completion, especially since declining oil prices have made it imperative that operators find more cost-effective methods of increasing production and reducing maintenance costs. The gas storage industry can effectively take advantage of the many recent advancements in CT technology.

  17. Theory of the quadrature elliptic birdcage coil.

    PubMed

    Leifer, M C

    1997-11-01

    This paper presents the theory of the quadrature birdcage coil wound on an elliptic cylindrical former. A conformal transformation of the ellipse to a circular geometry is used to derive the optimal sampling of the continuous surface current distribution to produce uniform magnetic fields within an elliptic cylinder. The analysis is rigorous for ellipses of any aspect ratio and shows how to produce quadrature operation of the elliptic birdcage with a conventional hybrid combiner. Insight gained from the transformation is also used to analyze field homogeneity, find the optimal RF shield shape, and specify component values to produce the correct current distribution in practice. Measurements and images from a 16-leg elliptic birdcage coil at both low and high frequencies show good quadrature performance, homogeneity, and sensitivity.

  18. Improved Sensing Coils for SQUIDs

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin; Hahn, Inseob; Eom, Byeong Ho

    2007-01-01

    An improvement in the design and fabrication of sensing coils of superconducting quantum interference device (SQUID) magnetometers has been proposed to increase sensitivity. It has been estimated that, in some cases, it would be possible to increase sensitivity by about half or to reduce measurement time correspondingly. The pertinent aspects of the problems of design and fabrication can be summarized as follows: In general, to increase the sensitivity of a SQUID magnetometer, it is necessary to maximize the magnetic flux enclosed by the sensing coil while minimizing the self-inductance of this coil. It is often beneficial to fabricate the coil from a thicker wire to reduce its self-inductance. Moreover, to optimize the design of the coil with respect to sensitivity, it may be necessary to shape the wire to other than a commonly available circular or square cross-section. On the other hand, it is not practical to use thicker superconducting wire for the entire superconducting circuit, especially if the design of a specific device requires a persistent-current loop enclosing a remotely placed SQUID sensor. It may be possible to bond a thicker sensing-coil wire to thinner superconducting wires leading to a SQUID sensor, but it could be difficult to ensure reliable superconducting connections, especially if the bonded wires are made of different materials. The main idea is to mold the sensing coil in place, to more nearly optimum cross sectional shape, instead of making the coil by winding standard pre-fabricated wire. For this purpose, a thin superconducting wire loop that is an essential part of the SQUID magnetometer would be encapsulated in a form that would serve as a mold. A low-melting-temperature superconducting metal (e.g., indium, tin, or a lead/tin alloy) would be melted into the form, which would be sized and shaped to impart the required cross section to the coil thus formed.

  19. Convective heat transfer enhancement inside tubes using inserted helical coils

    NASA Astrophysics Data System (ADS)

    Ali, R. K.; Sharafeldeen, M. A.; Berbish, N. S.; Moawed, M. A.

    2016-01-01

    Convective heat transfer was experimentally investigated in tubes with helical coils inserts in turbulent flow regime within Reynolds number range of 14400 ≤ Re ≤ 42900. The present work aims to extend the experimental data available on wire coil inserts to cover wire diameter ratio from 0.044 to 0.133 and coil pitch ratio from 1 to 5. Uniform heat flux was applied to the external surface of the tube and air was selected as fluid. The effects of Reynolds number and wire diameter and coil pitch ratios on the Nusselt number and friction factor were studied. The enhancement efficiency and performance criteria ranges are of (46.9-82.6%) and (100.1-128%) within the investigated range of the different parameters, respectively. Correlations are obtained for the average Nusselt number and friction factor utilizing the present measurements within the investigated range of geometrical parameters and Re.

  20. Rapid mixing of viscous liquids by electrical coiling

    NASA Astrophysics Data System (ADS)

    Kong, Tiantian; Li, Jingmei; Liu, Zhou; Zhou, Zhuolong; Ng, Peter Hon Yu; Wang, Liqiu; Shum, Ho Cheung

    2016-02-01

    The control for the processing of precursor liquids determines whether the properties and functions of the final material product can be engineered. An inherent challenge of processing viscous liquids arises from their large resistance to deform. Here, we report on the discovery of an electric approach that can significantly contribute to address this challenge. The applied electric force can induce a straight viscous jet to coil, and the resulting coiling characteristics are governed by the electric stress. We demonstrate the promising use of electrical coiling in the rapid and efficient mixing of viscous liquids. Remarkably, the degree of mixing can be precisely adjusted by tuning the applied electric stress. Our approach of controlling the coiling electrically has important implications on applications such as dispensing and printing of resins, printing patterned surfaces and scaffolds, processing of food and generating non-woven fabrics.

  1. Rapid mixing of viscous liquids by electrical coiling

    PubMed Central

    Kong, Tiantian; Li, Jingmei; Liu, Zhou; Zhou, Zhuolong; Ng, Peter Hon Yu; Wang, Liqiu; Shum, Ho Cheung

    2016-01-01

    The control for the processing of precursor liquids determines whether the properties and functions of the final material product can be engineered. An inherent challenge of processing viscous liquids arises from their large resistance to deform. Here, we report on the discovery of an electric approach that can significantly contribute to address this challenge. The applied electric force can induce a straight viscous jet to coil, and the resulting coiling characteristics are governed by the electric stress. We demonstrate the promising use of electrical coiling in the rapid and efficient mixing of viscous liquids. Remarkably, the degree of mixing can be precisely adjusted by tuning the applied electric stress. Our approach of controlling the coiling electrically has important implications on applications such as dispensing and printing of resins, printing patterned surfaces and scaffolds, processing of food and generating non-woven fabrics. PMID:26860660

  2. Coiled tubing. operations and services

    SciTech Connect

    Hightower, C.M. )

    1992-11-01

    Coiled tubing is being used with increasing frequency in conventional or traditional production operations. Demand for coiled pipe in these types of applications is expected to experience rapid growth as standard 2 (3/8) and 2 (7/8)-in. OD tubing sizes and units equipped to run larger pipe become more readily available. This paper reports on a recent market survey which indicated that coiled tubing used for velocity strings and standard production tubing installations are two areas with the most potential for immediate and near-term expansion. Other applications include: well casing and liners, gravel packing, artificial lift, flowlines and pipelines.

  3. Laminated magnet field coil sheath

    DOEpatents

    Skaritka, John R.

    1987-12-01

    a method for manufacturing a magnet cable trim coil in a sheath assembly for use in a cryogenic particle accelerator. A precisely positioned pattern of trim coil turns is bonded to a flexible substrate sheath that is capable of withstanding cryogenic operating conditions. In the method of the invention the flexible sheath, with the trim coil pattern precisely positioned thereon, is accurately positioned at a precise location relative to a bore tube assembly of an accelerator and is then bonded to the bore tube with a tape suitable for cryogenic application. The resultant assembly can be readily handled and installed within an iron magnet yoke assembly of a suitable cryogenic particle accelerator.

  4. Laminated magnet field coil sheath

    DOEpatents

    Skaritka, J.R.

    1987-05-15

    A method for manufacturing a magnetic cable trim coil in a sheath assembly for use in a cryogenic particle accelerator. A precisely positioned pattern of trim coil turns is bonded to a flexible substrate sheath that is capable of withstanding cryogenic operating conditions. In the method of the invention the flexible substrate sheath, with the trim coil pattern precisely location relative to a bore tube assembly of an accelerator and is then bonded to the bore tube with a tape suitable for cryogenic application. The resultant assembly can be readily handled and installed within an iron magnet yoke assembly of a suitable cryogenic particle accelerator. 1 fig.

  5. ASTROMAG coil cooling study

    NASA Technical Reports Server (NTRS)

    Maytal, Ben-Zion; Vansciver, Steven W.

    1990-01-01

    ASTROMAG is a planned particle astrophysics magnetic facility. Basically it is a large magnetic spectrometer outside the Earth's atmosphere for an extended period of time in orbit on a space station. A definition team summarized its scientific objectives assumably related to fundamental questions of astrophysics, cosmology, and elementary particle physics. Since magnetic induction of about 7 Tesla is desired, it is planned to be a superconducting magnet cooled to liquid helium 2 temperatures. The general structure of ASTROMAG is based on: (1) two superconducting magnetic coils, (2) dewar of liquid helium 2 to provide cooling capability for the magnets; (3) instrumentation, matter-anti matter spectrometer (MAS) and cosmic ray isotope spectrometer (CRIS); and (4) interfaces to the shuttle and space station. Many configurations of the superconducting magnets and the dewar were proposed and evaluated, since those are the heart of the ASTROMAG. Baseline of the magnet configuration and cryostat as presented in the phase A study and the one kept in mind while doing the present study are presented. ASTROMAG's development schedule reflects the plan of launching to the space station in 1995.

  6. A coil combination for magnetic resonance perfusion imaging of mice in vivo at 7 T

    NASA Astrophysics Data System (ADS)

    Streif, Jörg U. G.; Lanz, Titus; Griswold, Mark; Rommel, Eberhard; Haase, Axel

    2003-05-01

    A radio frequency (rf) coil combination of a birdcage resonator and a receive-only surface coil was developed for in vivo magnetic resonance imaging of mice at 7.0 T. Since this coil was designed for spin labeling perfusion measurements, the length of the birdcage resonator needed to be 110 mm at a diameter of 35 mm. This was challenging since this length extended 1/10 of the wavelength at the spectrometer Larmor frequency of 300.3 MHz. Symmetric drive with homogeneous B1 field was achieved by introduction of a new rf coupling scheme using an additional conductor path ring at zero potential. This design allowed a balanced drive of the coil without the use of an additional balun. The receive-only surface coil was realized as a single loop with a diameter of 24 mm. To avoid coupling between the coils, active decoupling using p-i-n diode switches was integrated. These switches showed good characteristics and the coil combination was not sensitive to effects such as contrast alterations, rf shielding of the transmit pulse by the receive coil, and possible receive coil destruction during transmission. The improved performance of the coil combination with respect to a stand-alone surface coil or a stand-alone birdcage resonator was demonstrated in phantoms and mice. In comparison with a stand-alone suface coil, the coil combination provided more uniform contrast behavior and an extended depth of view. In addition, the combination showed an improved signal-to-noise ratio with respect to a stand-alone birdcage resonator.

  7. Can Magnetic Coil Ease Tinnitus?

    MedlinePlus

    ... Go Back Sign up for VA Research Updates Technology Horizons Can magnetic coil ease tinnitus? VA trial ... help reduce the abnormal perception of sounds. The Food and Drug Administration approved the relatively painless treatment [ ...

  8. Adjustable Induction-Heating Coil

    NASA Technical Reports Server (NTRS)

    Ellis, Rod; Bartolotta, Paul

    1990-01-01

    Improved design for induction-heating work coil facilitates optimization of heating in different metal specimens. Three segments adjusted independently to obtain desired distribution of temperature. Reduces time needed to achieve required temperature profiles.

  9. Zero-angle helical coil

    NASA Technical Reports Server (NTRS)

    Troendle, J. A.

    1976-01-01

    Device is constructed of bimetallic stock material formed into segments of small diameters and fastened together by metal strips. Coil is useful in various types of actuators, such as temperature controls.

  10. Contrast-enhanced dynamic MRI protocol with improved spatial and time resolution for in vivo microimaging of the mouse with a 1.5-T body scanner and a superconducting surface coil.

    PubMed

    Ginefri, Jean-Christophe; Poirier-Quinot, Marie; Robert, Philippe; Darrasse, Luc

    2005-02-01

    Magnetic resonance imaging (MRI) is well suited for small animal model investigations to study various human pathologies. However, the assessment of microscopic information requires a high-spatial resolution (HSR) leading to a critical problem of signal-to-noise ratio limitations in standard whole-body imager. As contrast mechanisms are field dependent, working at high field do not allow to derive MRI criteria that may apply to clinical settings done in standard whole-body systems. In this work, a contrast-enhanced dynamic MRI protocol with improved spatial and time resolution was used to perform in vivo tumor model imaging on the mouse at 1.5 T. The needed sensitivity is provided by the use of a 12-mm superconducting surface coil operating at 77 K. High quality in vivo images were obtained and revealed well-defined internal structures of the tumor. A 3-D HSR sequence with voxels of 59x59x300 microm3 encoded within 6.9 min and a 2-D sequence with subsecond acquisition time and isotropic in-plane resolution of 234 microm were used to analyze the contrast enhancement kinetics in tumoral structures at long and short time scales. This work is a first step to better characterize and differentiate the dynamic behavior of tumoral heterogeneities.

  11. Dimeric coiled-coil structure of Saccharomyces cerevisiae Atg16 and its functional significance in autophagy.

    PubMed

    Fujioka, Yuko; Noda, Nobuo N; Nakatogawa, Hitoshi; Ohsumi, Yoshinori; Inagaki, Fuyuhiko

    2010-01-08

    Atg16 interacts with the Atg12-Atg5 protein conjugate through its N-terminal domain and self-assembles through its coiled-coil domain (CCD). Formation of the Atg12-Atg5.Atg16 complex is essential for autophagy, the bulk degradation process conserved among most eukaryotes. Here, we report the crystal structures of full-length Saccharomyces cerevisiae Atg16 at 2.8 A resolution and its CCD at 2.5 A resolution. The CCD and full-length Atg16 each exhibit an extended alpha-helix, 90 and 130 A, respectively, and form a parallel coiled-coil dimer in the crystals. Although the apparent molecular weight of Atg16 observed by gel-filtration chromatography suggests that Atg16 is tetrameric, an analytical ultracentrifugation study showed Atg16 as a dimer in solution, consistent with the crystal structure. Evolutionary conserved surface residues clustered at the C-terminal half of Atg16 CCD were shown to be crucial for autophagy. These results will give a structural basis for understanding the molecular functions and significance of Atg16 in autophagy.

  12. An improved current potential method for fast computation of stellarator coil shapes

    NASA Astrophysics Data System (ADS)

    Landreman, Matt

    2017-04-01

    Several fast methods for computing stellarator coil shapes are compared, including the classical NESCOIL procedure (Merkel 1987 Nucl. Fusion 27 867), its generalization using truncated singular value decomposition, and a Tikhonov regularization approach we call REGCOIL in which the squared current density is included in the objective function. Considering W7-X and NCSX geometries, and for any desired level of regularization, we find the REGCOIL approach simultaneously achieves lower surface-averaged and maximum values of both current density (on the coil winding surface) and normal magnetic field (on the desired plasma surface). This approach therefore can simultaneously improve the free-boundary reconstruction of the target plasma shape while substantially increasing the minimum distances between coils, preventing collisions between coils while improving access for ports and maintenance. The REGCOIL method also allows finer control over the level of regularization, it preserves convexity to ensure the local optimum found is the global optimum, and it eliminates two pathologies of NESCOIL: the resulting coil shapes become independent of the arbitrary choice of angles used to parameterize the coil surface, and the resulting coil shapes converge rather than diverge as Fourier resolution is increased. We therefore contend that REGCOIL should be used instead of NESCOIL for applications in which a fast and robust method for coil calculation is needed, such as when targeting coil complexity in fixed-boundary plasma optimization, or for scoping new stellarator geometries.

  13. The coiling of electrified liquid jets

    NASA Astrophysics Data System (ADS)

    Rivero Rodriguez, Javier; Pérez-Saborid, Miguel

    2013-11-01

    We have carried out a numerical study of the coiling regime which takes place when an electrified liquid jet issuing from an orifice drilled in a metal plate electrode reaches the counter electrode. Based on the slenderness assumption, we have derived the set of one-dimensional dynamical equations by averaging the underlying balance laws over the jet cross sections (Cosserat rod model). Therefore, our equations and boundary conditions are related to those obtained by N.M. Ribe (Ann. Rev Fluid Mech., 2012) for the coiling of liquid ropes, but including electrostatic effects. In a first approach, we have simplified the electrical terms entering the problem by assuming a constant external electric field between electrodes, and that the charges are convected by the jet surface interacting electrostatically with each other via the local interaction approximation (Yarin et al., 2001). We have numerically investigated the problem in order to analize how the coiling regime depends on the dimensionless parameters of the problem, i.e., the Reynolds number, the electrical Bond number and the capillary number. In particular, we have found that both the displacement of the centerline of the jet and its cross-sectional stretching greatly depend on the electrostatic effects. Thanks to the MINECO (Spain) for partial support under grant DPI2010-20450-C03-02.

  14. Coiling and Folding of Viscoelastic Jets

    NASA Astrophysics Data System (ADS)

    Majmudar, Trushant; Varagnat, Matthieu; McKinley, Gareth

    2007-11-01

    The study of fluid jets impacting on a flat surface has industrial applications in many areas, including processing of foods and consumer goods, bottle filling, and polymer melt processing. Previous studies have focused primarily on purely viscous, Newtonian fluids, which exhibit a number of different dynamical regimes including dripping, steady jetting, folding, and steady coiling. Here we add another dimension to the problem by focusing on mobile (low viscosity) viscoelastic fluids, with the study of two wormlike-micellar fluids, a cetylpyridinum-salicylic acid salt (CPyCl/NaSal) solution, and an industrially relevant shampoo base. We investigate the effects of viscosity and elasticity on the dynamics of axi-symmetric jets. The viscoelasticity of the fluids is systematically controlled by varying the concentration of salt counterions. Experimental methods include shear and extensional rheology measurements to characterize the fluids, and high-speed digital video imaging. In addition to the regimes observed in purely viscous systems, we also find a novel regime in which the elastic jet buckles and folds on itself, and alternates between coiling and folding behavior. We suggest phase diagrams and scaling laws for the coiling and folding frequencies through a systematic exploration of the experimental parameter space (height of fall, imposed flow rate, elasticity of the solution).

  15. Nylon screws make inexpensive coil forms

    NASA Technical Reports Server (NTRS)

    Aucoin, G.; Rosenthal, C.

    1978-01-01

    Standard nylon screws act as coil form copper wire laid down in spiral thread. Completed coil may be bonded to printed-circuit board. However, it is impossible to tune coil by adjusting spacing between windings, technique sometimes used with air-core coils.

  16. Equilibrium field coil concepts for INTOR

    SciTech Connect

    Strickler, D.J.; Peng, Y.K.M.; Brown, T.G.

    1981-08-01

    Methods are presented for reducing ampere-turn requirements in the EF coil system. It is shown that coil currents in an EF coil system external to the toroidal field coils can be substantially reduced by relaxing the triangularity of a D-shaped plasma. Further reductions are realized through a hybrid EF coil system using both internal and external coils. Equilibrium field coils for a poloidally asymmetric, single-null INTOR configuration are presented. It is shown that the shape of field lines in the plasma scrapeoff region and divertor channel improves as triangularity is reduced, but it does so at the possible expense of achievable stable beta values.

  17. PEALL4: a 4-channel, 12-bit, 40-MSPS, Power Efficient and Low Latency SAR ADC

    NASA Astrophysics Data System (ADS)

    Rarbi, F.; Dzahini, D.; Gallin-Martel, L.; Bouvier, J.; Zeloufi, M.; Trocme, B.; Gabaldon Ruiz, C.

    2015-01-01

    The PEALL4 chip is a Power Efficient And Low Latency 4-channels, 12-bit and 40-MSPS successive approximation register (SAR) ADC. It was designed featuring a very short latency time in the context of ATLAS Liquid Argon Calorimeter phase I upgrade. Moreover this design could be a good option for ATLAS phase II and other High Energy Physics (HEP) projects. The full functionality of the converter is achieved by an embedded high-speed clock frequency conversion generated by the ADC itself. The design and testing results of the PEALL4 chip implemented in a commercial 130nm CMOS process are presented. The size of this 4-channel ADC with embedded voltage references and sLVS output serializer is 2.8x3.4 mm2. The chip presents a short latency time less than 25 ns defined from the very beginning of the sampling to the last conversion bit made available. A total power consumption below 27mW per channel is measured including the reference buffer and the sLVS serializer.

  18. TRPM4 channels in the cardiovascular system: physiology, pathophysiology, and pharmacology.

    PubMed

    Abriel, Hugues; Syam, Ninda; Sottas, Valentin; Amarouch, Mohamed Yassine; Rougier, Jean-Sébastien

    2012-10-01

    The transient receptor potential channel (TRP) family comprises at least 28 genes in the human genome. These channels are widely expressed in many different tissues, including those of the cardiovascular system. The transient receptor potential channel melastatin 4 (TRPM4) is a Ca(2+)-activated non-specific cationic channel, which is impermeable to Ca(2+). TRPM4 is expressed in many cells of the cardiovascular system, such as cardiac cells of the conduction pathway and arterial and venous smooth muscle cells. This review article summarizes the recently described roles of TRPM4 in normal physiology and in various disease states. Genetic variants in the human gene TRPM4 have been linked to several cardiac conduction disorders. TRPM4 has also been proposed to play a crucial role in secondary hemorrhage following spinal cord injuries. Spontaneously hypertensive rats with cardiac hypertrophy were shown to over-express the cardiac TRPM4 channel. Recent studies suggest that TRPM4 plays an important role in cardiovascular physiology and disease, even if most of the molecular and cellular mechanisms have yet to be elucidated. We conclude this review article with a brief overview of the compounds that have been shown to either inhibit or activate TRPM4 under experimental conditions. Based on recent findings, the TRPM4 channel can be proposed as a future target for the pharmacological treatment of cardiovascular disorders, such as hypertension and cardiac arrhythmias.

  19. Automatic tuning of flexible interventional RF receiver coils.

    PubMed

    Venook, Ross D; Hargreaves, Brian A; Gold, Garry E; Conolly, Steven M; Scott, Greig C

    2005-10-01

    Microcontroller-based circuitry was built and tested for automatically tuning flexible RF receiver coils at the touch of a button. This circuitry is robust to 10% changes in probe center frequency, is in line with the scanner, and requires less than 1 s to tune a simple probe. Images were acquired using this circuitry with a varactor-tunable 1-inch flexible probe in a phantom and in an in vitro porcine knee model. The phantom experiments support the use of automatic tuning by demonstrating 30% signal-to-noise ratio (SNR) losses for 5% changes in coil center frequency, in agreement with theoretical calculations. Comparisons between patellofemoral cartilage images obtained using a 3-inch surface coil and the surgically-implanted 1-inch flexible coil reveal a worst-case local SNR advantage of a factor of 4 for the smaller coil. This work confirms that surgically implanted coils can greatly improve resolution in small-field-of-view (FOV) applications, and demonstrates the importance and feasibility of automatically tuning such probes.

  20. Magnetic resonance imaging of rodent spinal cord with an improved performance coil at 7 Tesla

    NASA Astrophysics Data System (ADS)

    Solis-Najera, S. E.; Rodriguez, A. O.

    2014-11-01

    Magnetic Resonance Imaging of animal models provide reliable means to study human diseases. The image acquisition particularly determined by the radio frequency coil to detect the signal emanated from a particular region of interest. A scaled-down version of the slotted surface coil was built based on the previous results of a magnetron-type surface coil for human applications. Our coil prototype had a 2 cm total diameter and six circular slots and was developed for murine spinal cord at 7 T. Electromagnetic simulations of the slotted and circular coils were also performed to compute the spatially dependent magnetic and electric fields using a simulated saline-solution sphere. The quality factor of both coils was experimentally measured giving a lower noise figure and a higher quality factor for the slotted coil outperforming the circular coil. Images of the spinal cord of a rat were acquired using standard pulse sequences. The slotted surface coil can be a good tool for spinal cord rat imaging using conventional pulse sequences at 7 T.

  1. HTS planar gradiometer consisting of SQUID with multi-turn input coil and large pickup coil made of GdBCO coated conductor

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Akira; Adachi, Seiji; Oshikubo, Yasuo; Hato, Tsunehiro; Enpuku, Keiji; Sugisaki, Masaki; Arai, Eiichi; Tanabe, Keiichi

    2013-01-01

    We have investigated the fabrication of a high-temperature superconducting (HTS) gradiometer with long baseline for geophysical applications. The proof-of-concept gradiometer using a 1-turn pickup coil made of a GdBa2Cu3Oy coated conductor (GCC) and 5.5-turn input coil integrated on a SQUID was fabricated in our previous work. In this study, we have optimized the device structure to improve the frequency response, gradient field sensitivity and gradiometer balance. The fabricated flux transformer consists of a 6-turn planar gradiometric pickup coil and a 26-turn input coil made of an HTS thin film. A low-melting-point alloy was used to connect polished Ag surfaces of the CGG pickup coil and Au pads of the input coil. An HTS SQUID was formed on another substrate and stacked on the input coil. A mechanical balancing structure using three pieces of GCC as a superconducting shield was also implemented. The fabricated gradiometer showed a gradient field noise of 0.8 fT/cm Hz1/2 in the white noise regions, a gradiometer balance of 1/142, and a cutoff frequency of 9 Hz corresponding to a 2 mΩ contact resistance between the pickup coil and the input coil.

  2. Structural basis for cargo binding and autoinhibition of Bicaudal-D1 by a parallel coiled-coil with homotypic registry

    SciTech Connect

    Terawaki, Shin-ichi; Yoshikane, Asuka; Higuchi, Yoshiki; Wakamatsu, Kaori

    2015-05-01

    Bicaudal-D1 (BICD1) is an α-helical coiled-coil protein mediating the attachment of specific cargo to cytoplasmic dynein. It plays an essential role in minus end-directed intracellular transport along microtubules. The third C-terminal coiled-coil region of BICD1 (BICD1 CC3) has an important role in cargo sorting, including intracellular vesicles associating with the small GTPase Rab6 and the nuclear pore complex Ran binding protein 2 (RanBP2), and inhibiting the association with cytoplasmic dynein by binding to the first N-terminal coiled-coil region (CC1). The crystal structure of BICD1 CC3 revealed a parallel homodimeric coiled-coil with asymmetry and complementary knobs-into-holes interactions, differing from Drosophila BicD CC3. Furthermore, our binding study indicated that BICD1 CC3 possesses a binding surface for two distinct cargos, Rab6 and RanBP2, and that the CC1-binding site overlaps with the Rab6-binding site. These findings suggest a molecular basis for cargo recognition and autoinhibition of BICD proteins during dynein-dependent intracellular retrograde transport. - Highlights: • BICD1 CC3 is a parallel homodimeric coiled-coil with axial asymmetry. • The coiled-coil packing of BICD1 CC3 is adapted to the equivalent heptad position. • BICD1 CC3 has distinct binding sites for two classes of cargo, Rab6 and RanBP2. • The CC1-binding site of BICD1 CC3 overlaps with the Rab6-binding site.

  3. Liquid Crystalline Assembly of Coil-Rod-Coil Molecules with Lateral Methyl Groups into 3-D Hexagonal and Tetragonal Assemblies

    PubMed Central

    Wang, Zhuoshi; Lan, Yu; Zhong, Keli; Liang, Yongri; Chen, Tie; Jin, Long Yi

    2014-01-01

    In this paper, we report the synthesis and self-assembly behavior of coil-rod-coil molecules, consisting of three biphenyls linked through a vinylene unit as a conjugated rod segment and poly(ethylene oxide) (PEO) with a degree of polymerization (DP) of 7, 12 and 17, incorporating lateral methyl groups between the rod and coil segments as the coil segment. Self-organized investigation of these molecules by means of differential scanning calorimetry (DSC), thermal polarized optical microscopy (POM) and X-ray diffraction (XRD) reveals that the lateral methyl groups attached to the surface of rod and coil segments, dramatically influence the self-assembling behavior in the liquid-crystalline mesophase. Molecule 1 with a relatively short PEO coil length (DP = 7) self-assembles into rectangular and oblique 2-dimensional columnar assemblies, whereas molecules 2 and 3 with DP of 12 and 17 respectively, spontaneously self-organize into unusual 3-dimensional hexagonal close-packed or body-centered tetragonal assemblies. PMID:24699045

  4. Computational analysis of residue contributions to coiled-coil topology.

    PubMed

    Ramos, Jorge; Lazaridis, Themis

    2011-11-01

    A variety of features are thought to contribute to the oligomeric and topological specificity of coiled coils. In previous work, we examined the determinants of oligomeric state. Here, we examine the energetic basis for the tendency of six coiled-coil peptides to align their α-helices in antiparallel orientation using molecular dynamics simulations with implicit solvation (EEF1.1). We also examine the effect of mutations known to disrupt the topology of these peptides. In agreement with experiment, ARG or LYS at a or d positions were found to stabilize the antiparallel configuration. The modeling suggests that this is not due to a-a' or d-d' repulsions but due to interactions with e' and g' residues. TRP at core positions also favors the antiparallel configuration. Residues that disfavor parallel dimers, such as ILE at d, are better tolerated in, and thus favor the antiparallel configuration. Salt bridge networks were found to be more stabilizing in the antiparallel configuration for geometric reasons: antiparallel helices point amino acid side chains in opposite directions. However, the structure with the largest number of salt bridges was not always the most stable, due to desolvation and configurational entropy contributions. In tetramers, the extent of stabilization of the antiparallel topology by core residues is influenced by the e' residue on a neighboring helix. Residues at b and c positions in some cases also contribute to stabilization of antiparallel tetramers. This work provides useful rules toward the goal of designing coiled coils with a well-defined and predictable three-dimensional structure.

  5. The AFM Observation of Single Polyethylene Molecules in Coiled State on Mica

    NASA Astrophysics Data System (ADS)

    Prokhorov, V. V.; Yaminsky, I. V.

    2003-12-01

    Single polyethylene molecules and their small aggregates have been deposited on mica from diluted solutions at elevated temperatures and visualized by AFM in coiled and crystalline states. Coils have two-dimensional conformations with both highly tangled sites and locally extended segments with a length much exceeding the persistent length in a solution. The length measurements of coils reveal a wide distribution with the length of a maximum much smaller than the length of fully stretched molecules, moreover the long coils have been observed indicating the existence of linear multimolecular aggregates. Two models have been considered for the explanation of the observed deficit in the coils length, correspondingly the model implying the substantial smoothing of a winding chain trajectory due to the lack of the AFM resolution and the model of locally extended surface conformations with the long intramolecular folds. The roots of the apparent negative AFM height contrast of coils have been discussed.

  6. Compact 4-channel AWGs for CWDM and LAN WDM in data center monolithic applications

    NASA Astrophysics Data System (ADS)

    Pan, Pan; An, Junming; Wang, Yue; Zhang, Jiashun; Wang, Liangliang; Qi, Ying; Han, Qin; Hu, Xiongwei

    2015-12-01

    InP-based 4-channel AWGs for Coarse Wavelength Division Multiplexing (CWDM) with channel spacing of 20 nm and Local Area Network (LAN) WDM with channel spacing of 800 GHz are designed and fabricated. The deep-ridge waveguide is used to make the chip compact, chip size of AWG for CWDM is 0.55×3.9 mm2 and for LAN WDM is 1.6×3 mm2. The measured results indicate that, the insertion losses are -5 dB and -7 dB, crosstalk levels are below -25 dB and -24 dB for AWG with 20 nm channel spacing and 800 GHz channel spacing, respectively. These AWGs can be integrated with lasers and detectors array monolithically for data center applications.

  7. The structure of the GemC1 coiled coil and its interaction with the Geminin family of coiled-coil proteins

    SciTech Connect

    Caillat, Christophe; Fish, Alexander; Pefani, Dafni-Eleftheria; Taraviras, Stavros; Lygerou, Zoi; Perrakis, Anastassis

    2015-10-31

    The GemC1 coiled-coil structure has subtle differences compared with its homologues Geminin and Idas. Co-expression experiments in cells and biophysical stability analysis of the Geminin-family coiled coils suggest that the GemC1 coiled coil alone is unstable. GemC1, together with Idas and Geminin, an important regulator of DNA-replication licensing and differentiation decisions, constitute a superfamily sharing a homologous central coiled-coil domain. To better understand this family of proteins, the crystal structure of a GemC1 coiled-coil domain variant engineered for better solubility was determined to 2.2 Å resolution. GemC1 shows a less typical coiled coil compared with the Geminin homodimer and the Geminin–Idas heterodimer structures. It is also shown that both in vitro and in cells GemC1 interacts with Geminin through its coiled-coil domain, forming a heterodimer that is more stable that the GemC1 homodimer. Comparative analysis of the thermal stability of all of the possible superfamily complexes, using circular dichroism to follow the unfolding of the entire helix of the coiled coil, or intrinsic tryptophan fluorescence of a unique conserved N-terminal tryptophan, shows that the unfolding of the coiled coil is likely to take place from the C-terminus towards the N-terminus. It is also shown that homodimers show a single-state unfolding, while heterodimers show a two-state unfolding, suggesting that the dimer first falls apart and the helices then unfold according to the stability of each protein. The findings argue that Geminin-family members form homodimers and heterodimers between them, and this ability is likely to be important for modulating their function in cycling and differentiating cells.

  8. Coiled tubing -- Operations and services

    SciTech Connect

    Sas-Jaworsky, A. II ); Blount, C.G. ); Tailby, R.J. )

    1993-06-01

    This paper reviews three industry authority's views on developments that will impact coiled tubing equipment and techniques for conventional land locations, Arctic and harsh offshore environments. Examples which are provided include the development of high-strength steels, composite pipe, integral lift devices, abrasive jet drilling, and extended reach drilling. It discusses the application of coiled tubing to well completion and maintenance, including the applications to plugged pipelines. The use of new steels and alloys help increase the corrosion resistance of the drilling stem along with greater load-bearing capacity. The economic advantages of coiled drilling versus jointed tubing drilling is somewhat more questionable as the cost for downhole motors and directional tools remain prohibitively high and borehole diameters remain small.

  9. Transient voltage oscillations in coils

    SciTech Connect

    Chowdhuri, P.

    1985-01-01

    Magnet coils may be excited into internal voltage oscillations by transient voltages. Such oscillations may electrically stress the magnet's dielectric components to many times its normal stress. This may precipitate a dielectric failure, and the attendant prolonged loss of service and costly repair work. Therefore, it is important to know the natural frequencies of oscillations of a magnet during the design stage, and to determine whether the expected switching transient voltages can excite the magnet into high-voltage internal oscillations. The series capacitance of a winding significantly affects its natural frequencies. However, the series capacitance is difficult to calculate, because it may comprise complex capacitance network, consisting of intra- and inter-coil turn-to-turn capacitances of the coil sections. A method of calculating the series capacitance of a winding is proposed. This method is rigorous but simple to execute. The time-varying transient voltages along the winding are also calculated.

  10. Structural Basis for the cAMP-dependent Gating in the Human HCN4 Channel

    SciTech Connect

    X Xu; Z Vysotskaya; Q Liu; L Zhou

    2011-12-31

    Hyperpolarization-activated cAMP-regulated (HCN) channels play important physiological roles in both cardiovascular and central nervous systems. Among the four HCN isoforms, HCN2 and HCN4 show high expression levels in the human heart, with HCN4 being the major cardiac isoform. The previously published crystal structure of the mouse HCN2 (mHCN2) C-terminal fragment, including the C-linker and the cyclic-nucleotide binding domain (CNBD), has provided many insights into cAMP-dependent gating in HCN channels. However, structures of other mammalian HCN channel isoforms have been lacking. Here we used a combination of approaches including structural biology, biochemistry, and electrophysiology to study cAMP-dependent gating in HCN4 channel. First we solved the crystal structure of the C-terminal fragment of human HCN4 (hHCN4) channel at 2.4 {angstrom}. Overall we observed a high similarity between mHCN2 and hHCN4 crystal structures. Functional comparison between two isoforms revealed that compared with mHCN2, the hHCN4 protein exhibited marked different contributions to channel function, such as a {approx}3-fold reduction in the response to cAMP. Guided by structural differences in the loop region between {beta}4 and {beta}5 strands, we identified residues that could partially account for the differences in response to cAMP between mHCN2 and hHCN4 proteins. Moreover, upon cAMP binding, the hHCN4 C-terminal protein exerts a much prolonged effect in channel deactivation that could have significant physiological contributions.

  11. De novo designed coiled-coil proteins with variable conformations as components of molecular electronic devices.

    PubMed

    Shlizerman, Clara; Atanassov, Alexander; Berkovich, Inbal; Ashkenasy, Gonen; Ashkenasy, Nurit

    2010-04-14

    Conformational changes of proteins are widely used in nature for controlling cellular functions, including ligand binding, oligomerization, and catalysis. Despite the fact that different proteins and artificial peptides have been utilized as electron-transfer mediators in electronic devices, the unique propensity of proteins to switch between different conformations has not been used as a mechanism to control device properties and performance. Toward this aim, we have designed and prepared new dimeric coiled-coil proteins that adopt different conformations due to parallel or antiparallel relative orientations of their monomers. We show here that controlling the conformation of these proteins attached as monolayers to gold, which dictates the direction and magnitude of the molecular dipole relative to the surface, results in quantitative modulation of the gold work function. Furthermore, charge transport through the proteins as molecular bridges is controlled by the different protein conformations, producing either rectifying or ohmic-like behavior.

  12. Electromagnetic Gun With Commutated Coils

    NASA Technical Reports Server (NTRS)

    Elliott, David G.

    1991-01-01

    Proposed electromagnetic gun includes electromagnet coil, turns of which commutated in sequence along barrel. Electrical current fed to two armatures by brushes sliding on bus bars in barrel. Interaction between armature currents and magnetic field from coil produces force accelerating armature, which in turn, pushes on projectile. Commutation scheme chosen so magnetic field approximately coincides and moves with cylindrical region defined by armatures. Scheme has disadvantage of complexity, but in return, enables designer to increase driving magnetic field without increasing armature current. Attainable muzzle velocity increased substantially.

  13. Coiled tubing; Operations and services

    SciTech Connect

    Sas-Jaworsky, A. II )

    1991-12-01

    This article outlines the minimum safety requirements that should be considered for onshore and offshore oil well service operations with coiled tubing equipment. These guidelines comply with Minerals Management Service (MMS) regulations issued on May 31, 1988, for offshore work. Where specific MMS regulations are sited, the regulation reference, Incident of Non-Compliance (INC), number is provided. These guidelines can be used by operators and contractors, and although U.S. offshore operations are emphasized, they are applicable wherever coiled tubing services are used.

  14. INTERCOMPARISON OF PERFORMANCE OF RF COIL GEOMETRIES FOR HIGH FIELD MOUSE CARDIAC MRI

    PubMed Central

    Constantinides, Christakis; Angeli, S.; Gkagkarellis, S.; Cofer, G.

    2012-01-01

    Multi-turn spiral surface coils are constructed in flat and cylindrical arrangements and used for high field (7.1 T) mouse cardiac MRI. Their electrical and imaging performances, based on experimental measurements, simulations, and MRI experiments in free space, and under phantom, and animal loading conditions, are compared with a commercially available birdcage coil. Results show that the four-turn cylindrical spiral coil exhibits improved relative SNR (rSNR) performance to the flat coil counterpart, and compares fairly well with a commercially available birdcage coil. Phantom experiments indicate a 50% improvement in the SNR for penetration depths ≤ 6.1 mm from the coil surface compared to the birdcage coil, and an increased penetration depth at the half-maximum field response of 8 mm in the 4-spiral cylindrical coil case, in contrast to 2.9 mm in the flat 4-turn spiral case. Quantitative comparison of the performance of the two spiral coil geometries in anterior, lateral, inferior, and septal regions of the murine heart yield maximum mean percentage rSNR increases of the order of 27–167% in vivo post-mortem (cylindrical compared to flat coil). The commercially available birdcage outperforms the cylindrical spiral coil in rSNR by a factor of 3–5 times. The comprehensive approach and methodology adopted to accurately design, simulate, implement, and test radiofrequency coils of any geometry and type, under any loading conditions, can be generalized for any application of high field mouse cardiac MRI. PMID:23204945

  15. Spectroscopy With Surface Coils and Decoupling

    ClinicalTrials.gov

    2015-12-23

    Adrenal Cortical Cancer; Brain Cancer; Breast Cancer; CNS Cancer; Colon Cancer; HEENT Cancer; Hodgkin's Disease; Kaposi's Sarcoma; Liver Cancer; Lung Cancer; Non-Hodgkin's Lymphoma; Ovarian Cancer; Pancreatic Cancer; Prostate Cancer; Rectal Cancer; Renal Cancer; Sarcoma; Squamous Cell Carcinoma; Thyroid Cancer

  16. [Two Cases of Ruptured Cerebral Aneurysm Complicated with Delayed Coil Protrusion after Coil Embolization].

    PubMed

    Furukawa, Takashi; Ogata, Atsushi; Ebashi, Ryo; Takase, Yukinori; Masuoka, Jun; Kawashima, Masatou; Abe, Tatsuya

    2016-07-01

    We report two cases of delayed coil protrusion after coil embolization for ruptured cerebral aneurysms. Case 1:An 82-year-old woman with a subarachnoid hemorrhage due to a ruptured small anterior communicating artery aneurysm underwent successful coil embolization. Eighteen days after the procedure, coil protrusion from the aneurysm into the right anterior cerebral artery was observed without any symptoms. Further coil protrusion did not develop after 28 days. Case 2:A 78-year-old woman with a subarachnoid hemorrhage due to a ruptured small left middle cerebral artery aneurysm underwent successful coil embolization. Twenty days after the procedure, coil protrusion from the aneurysm into the left middle cerebral artery was observed, with a transient ischemic attack. Further coil protrusion did not develop. Both patients recovered with antithrombotic treatment. Even though delayed coil protrusion after coil embolization is rare, it should be recognized as a long-term complication of coil embolization for cerebral aneurysms.

  17. A MRI rotary phased array head coil.

    PubMed

    Li, Bing Keong; Weber, Ewald; Crozier, Stuart

    2013-08-01

    A new rotary phased array (RPA) head coil that can provide homogenous brain images comparable to volumetric radiofrequency coils is proposed for magnetic resonance brain imaging applications. The design of the RPA head coil is a departure from conventional circumferential array design method, as coil elements of the RPA head coil have a "paddle-like" structure consisting of a pair of main conductors located on opposite sides, inserted equi-angularly around and over the head. A prototype 2T receive-only 4-element RPA head coil was constructed and experimentally tested against a conventional receive-only 4-element phased array head coil and a commercial receive-only quadrature birdcage head coil. Homogenous phantom images acquired by the RPA head coil show that signal intensity deep at the center of the phantom was improved as compared to the conventional phased array head coil and this improvement allow the RPA head coil to acquire homogenous brain images similar to brain images acquired with the birdcage head coil. In addition, partial parallel imaging was used in conjunction with the RPA head coil to enable rapid imaging.

  18. Coil Embolization for Intracranial Aneurysms

    PubMed Central

    2006-01-01

    Executive Summary Objective To determine the effectiveness and cost-effectiveness of coil embolization compared with surgical clipping to treat intracranial aneurysms. The Technology Endovascular coil embolization is a percutaneous approach to treat an intracranial aneurysm from within the blood vessel without the need of a craniotomy. In this procedure, a microcatheter is inserted into the femoral artery near the groin and navigated to the site of the aneurysm. Small helical platinum coils are deployed through the microcatheter to fill the aneurysm, and prevent it from further expansion and rupture. Health Canada has approved numerous types of coils and coil delivery systems to treat intracranial aneurysms. The most favoured are controlled detachable coils. Coil embolization may be used with other adjunct endovascular devices such as stents and balloons. Background Intracranial Aneurysms Intracranial aneurysms are the dilation or ballooning of part of a blood vessel in the brain. Intracranial aneurysms range in size from small (<12 mm in diameter) to large (12–25 mm), and to giant (>25 mm). There are 3 main types of aneurysms. Fusiform aneurysms involve the entire circumference of the artery; saccular aneurysms have outpouchings; and dissecting aneurysms have tears in the arterial wall. Berry aneurysms are saccular aneurysms with well-defined necks. Intracranial aneurysms may occur in any blood vessel of the brain; however, they are most commonly found at the branch points of large arteries that form the circle of Willis at the base of the brain. In 85% to 95% of patients, they are found in the anterior circulation. Aneurysms in the posterior circulation are less frequent, and are more difficult to treat surgically due to inaccessibility. Most intracranial aneurysms are small and asymptomatic. Large aneurysms may have a mass effect, causing compression on the brain and cranial nerves and neurological deficits. When an intracranial aneurysm ruptures and bleeds

  19. A new technique to optimize coil winding path for the arbitrarily distributed magnetic field and application to CHS-qa modular coils

    NASA Astrophysics Data System (ADS)

    Abe, M.; Nakayama, T.; Okamura, S.; Matsuoka, K.

    2004-11-01

    A new technique to calculate an arbitrarily shaped coil winding path for a target magnetic field distribution has been developed. The technique is called DUCAS (Design tool Using Current potentials And SVD, SVD= Singular Value Decomposition). The coil winding surface (CWS) is modeled by triangular finite elements (FEs). The SVD is applied on the response matrix from the current potentials (CPs) of the FE nodes to the magnetic field, to get eigen distribution functions of CPs and singular values (SVs). Using the eigen functions with large SVs, the CP distribution is determined on the CWS so as to reproduce a given magnetic field distribution. Discrete coil shapes are determined along the contour (flow) lines of CPs. The arbitrarily formed CWS is acceptable in DUCAS. We applied the DUCAS on CHS-qa (quasi-axisymmetric Compact Helical System) modular coils and confirmed that the technique is applicable on designs of helical system modular coils.

  20. Evaluating passively shielded gradient coil configurations for optimal eddy current compensation

    NASA Astrophysics Data System (ADS)

    Sanchez Lopez, Hector; Poole, Michael; Crozier, Stuart

    2010-05-01

    In magnetic resonance imaging, rapidly switching magnetic fields are used to spatially encode the signal. The temporal change of these fields induces eddy currents in nearby conducting structures of the scanner. These eddy currents, in turn, generate a secondary magnetic field that opposes and distorts the desired gradient field. Eddy current compensation methods are generally applied assuming that the primary and secondary magnetic field gradients possess similar spatial characteristics in the imaging volume (field matching). In this work an optimization method is used to deform the shape of the coil support and/or a highly conductive passive shield in order to improve the field matching and reduce the inductive coupling between the gradient coil and the passive shield. Using the residual field after eddy current compensation as the objective function, the coil support and/or conducting surfaces were deformed to obtain passively shielded x- and z-gradient coils with improved field matching and eddy current compensation. Assuming a single frequency, quasi-static simulation, it was demonstrated that the residual field was reduced up to 24 times by reshaping the coil and passive shield surfaces due to the improved field matching. However, using transient analyses we showed that in the case of the passively shielded x-gradient coil the residual field may only be reduced by five times from a cylindrical coil configuration. A bulge shape is created in the conducting surface as a mechanism of matching the field and at the same time reducing the mutual inductive coupling between the coil and the passive shield. An actively shielded coil with control over the magnetic field produced by the induced current was used as a reference coil that produces the minimal residual field. The actively shielded gradient coil produces minimal residual field for short and long pulses in the transient analyses.

  1. Finite element coiled cochlea model

    NASA Astrophysics Data System (ADS)

    Isailovic, Velibor; Nikolic, Milica; Milosevic, Zarko; Saveljic, Igor; Nikolic, Dalibor; Radovic, Milos; Filipović, Nenad

    2015-12-01

    Cochlea is important part of the hearing system, and thanks to special structure converts external sound waves into neural impulses which go to the brain. Shape of the cochlea is like snail, so geometry of the cochlea model is complex. The simplified cochlea coiled model was developed using finite element method inside SIFEM FP7 project. Software application is created on the way that user can prescribe set of the parameters for spiral cochlea, as well as material properties and boundary conditions to the model. Several mathematical models were tested. The acoustic wave equation for describing fluid in the cochlea chambers - scala vestibuli and scala timpani, and Newtonian dynamics for describing vibrations of the basilar membrane are used. The mechanical behavior of the coiled cochlea was analyzed and the third chamber, scala media, was not modeled because it does not have a significant impact on the mechanical vibrations of the basilar membrane. The obtained results are in good agreement with experimental measurements. Future work is needed for more realistic geometry model. Coiled model of the cochlea was created and results are compared with initial simplified coiled model of the cochlea.

  2. Coiled tubing; Operations and services

    SciTech Connect

    Welch, J.L. ); Whitlow, R.R. )

    1992-07-01

    This paper reports that pulling tubing to clean out a production liner at Prudhoe Bay Unit Western Operating Area (PBU WOA) averages $600,000 to $800,000. Coiled tubing underreaming was developed to accomplish this objective at lower costs. Beginning in 1988, these operations have been improved through several generations of procedures and tool designs. Using current technology, the underreamer, in conjunction with coiled tubing, can reduce the cost of drilling out to a liner to about $50,000 or $100,000, depending on the amount and type of material to be removed. PBU WOA, operated by BP Exploration, produces about 600,000 bopd from 395 wells. Another 61 wells are used to inject produced water, seawater and miscible fluids. Most of the remedial well servicing operations are conducted using coiled tubing (CT). Three contract coiled tubing units (CTUs) work daily, performing wellbore cleanouts, stimulations, inflatable bridge plug installations and cement squeeze operations. About 42 underreaming jobs were performed from 1990 to 1991 at PBU WOA for an average cost of between $75,000 and $100,000, a cost savings of $500,000 power well compared to pulling tubing and cleaning out the wells conventionally.

  3. Pulsed COIL initiated by discharge

    NASA Astrophysics Data System (ADS)

    Yuryshev, Nikolai N.

    2004-06-01

    Pulsed mode makes COIL possible to produce pulses which power can significantly exceed that of CW COIL mode at the same flowrate of chemicals. Such a mode can find application in material treatment, in drilling for oil wells, as an optical locator, in laser frequency conversion via non-linear processes, in laser propulsion, etc. The method of volume generation of iodine atoms was shown to be the most effective one in generation of high power pulses. The base of method is substitution of molecular iodine in operation mixture for iodide which is stable in the mixture with singlet oxygen, and subsequent forced dissociation of iodide. In this approach the advantage of direct I-atom injection in laser active medium is demonstrated. The comparison of experimental results obtained with different sources used for iodide dissociation shows the electric discharge provides significantly higher electrical laser efficiency in comparison with photolysis initiation. At the same time, the specific energy of the electric discharge initiated COIL is at disadvantage in relation with that obtained with photolysis initiation. This fact is a result of active medium temperature increase due to insufficient initiation selectivity of electric discharge. Both longitudinal and transverse electric discharges were investigated as possible sources for laser initiation. The transverse discharge is more promising for increased operation pressure of active medium. The operation pressure is limited by dark reaction of iodide with singlet delta oxygen. The repetitively pulsed operation with repetition rate of up to 75 Hz of pulsed COIL is demonstrated.

  4. Coupled coils, magnets and Lenz's law

    NASA Astrophysics Data System (ADS)

    Thompson, Frank

    2010-03-01

    Great scientists in the past have experimented with coils and magnets. Here we have a variation where coupling occurs between two coils and the oscillatory motion of two magnets to give somewhat surprising results.

  5. Alternating current losses in superconducting coils

    NASA Technical Reports Server (NTRS)

    Wipf, S. L.; Guderjahn, C. A.

    1972-01-01

    Report examines relationship between coil loss and frequency and heat loss in coil as a function of the magnetic field H. Information is of value to manufacturers of superconducting magnets, motors and generators.

  6. Coupled Coils, Magnets and Lenz's Law

    ERIC Educational Resources Information Center

    Thompson, Frank

    2010-01-01

    Great scientists in the past have experimented with coils and magnets. Here we have a variation where coupling occurs between two coils and the oscillatory motion of two magnets to give somewhat surprising results. (Contains 6 figures and 1 footnote.)

  7. Eddy current gauge for monitoring displacement using printed circuit coil

    DOEpatents

    Visioli, Jr., Armando J.

    1977-01-01

    A proximity detection system for non-contact displacement and proximity measurement of static or dynamic metallic or conductive surfaces is provided wherein the measurement is obtained by monitoring the change in impedance of a flat, generally spiral-wound, printed circuit coil which is excited by a constant current, constant frequency source. The change in impedance, which is detected as a corresponding change in voltage across the coil, is related to the eddy current losses in the distant conductive material target. The arrangement provides for considerable linear displacement range with increased accuracies, stability, and sensitivity over the entire range.

  8. Radiofrequency Coil Designs For Nuclear Magnetic Resonance Zeuciviatographic Imaging

    NASA Astrophysics Data System (ADS)

    Bernardo, M. L.; Cohen, A. J.; Lauterbur, P. C.

    1982-11-01

    The requirements for spatial uniformity of the radio-frequency magnetic field used in three-dimensional MAR imaging are discussed and an improved winding distribution for a saddle-shaped single transmitter-receiver coil has been developed and tested by computer simulation of the rf mag-netic field pattern. The use of flat local or "surface" coils for NMR imaging is also proposed. A. method for correcting such images for the apparent spin density differences caused by the extreme rf magnetic field nonuniformity has been developed and tested with phantoms and images of the human back.

  9. Performance of an induction coil gun

    SciTech Connect

    Shokair, I.R.; Cowan, M.; Kaye, R.J.; Marder, B.M.

    1993-10-01

    Performance of an electromagnetic induction launcher is considered for three types of armatures. These are: Solid, 1-element wound and 16-element wound aluminum ar natures. The one element wound armature has uniform current density throughout. Because of the radial distribution of the current density, the wound armature can withstand field reversal (working against embedded flux in the armature) and still maintain low temperature. Slingshot simulations were performed, for several configurations. Best performance was obtained for a single element wound armature with two field reversals. For a 60 kg projectile, 10.5 cm coil inner radius and 5.5 cm coil build, the velocity after 50 meters of launcher length (670 stages) exceeded 3.5 km/sec with an overall efficiency of about 45%. For the same parameters the solid and 16-element wound armatures reach a velocity of about 3.3 km/sec after 800 stages (60 meters of launcher length) but without field reversal. A velocity of 3.5 km/sec is possible after 60 meters of launcher length with the 16-element wound armature with one field reversal, but the temperature is close to the melting temperature of aluminum. In all simulations with a solid armature, melting of some of the surface material occurs. However, it is shown that most of the melting occurs after contribution has been made to the forward going pressure, that is, melting does not affect the electrical performance of the launcher. The effect of coil firing tune jitter on launcher performance is also considered and is found to be very small for realistic perturbations. For {plus_minus}2 {mu}-secs random jitter, the reduction in the final velocity for a 60 meter launcher with a solid armature is less than 0.1% and the increase in temperature is only 2%. This result holds for all types of armatures.

  10. Performance of an induction coil launcher

    SciTech Connect

    Shokair, I.R.; Cowan, M.; Kaye, R.J.; Marder, B.M.

    1993-12-31

    Performance of an electromagnetic induction launcher is considered for three types of armatures. These are: Solid, 1-element wound and 16-element wound aluminum armatures. The one element wound armature has uniform current density throughout. Because of the uniformity of the current density, the wound armature can withstand field reversal and still maintain low temperature. Slingshot simulations were performed for several configurations. Best performance was obtained for a single element wound armature with two field reversals. For a 60 kg projectile, 10.5 cm coil inner radius and 5.5 cm coil build, the velocity after 50 meters of launcher length (670 stages) exceeded 3.5 km/sec with an overall efficiency of about 45%. For the same parameters the solid and 16-element wound armatures reach a velocity of about 3.3 km/sec after 800 stages (60 meters of launcher length) but without field reversal. A velocity of 3.5 km/sec is possible after 60 meters of launcher length with the 16-element wound armature with one field reversal, but the temperature is close to the melting temperature of aluminum. In all simulations with a solid armature, melting of some of the surface material occurs. However, it is shown that most of the melting occurs after contribution has been made to the forward going pressure, that is, melting does not affect the electrical performance of the launcher. The effect of coil firing time jitter on launcher performance is also considered and is found to be very small for realistic perturbations. For {plus_minus} 2 {mu}-secs random jitter, the reduction in the final velocity for a 60 meter launcher with a solid armature is less than 0.1% and the increase in temperature is only 2%. This result holds for all types of armatures.

  11. Coiled tubing solves multiple downhole problems

    SciTech Connect

    Bedford, S. ); Smith, I. )

    1994-11-01

    Declining reservoir pressure and water breakthrough in the UK North Sea Magnus field has coincided with general advances in application of coiled tubing and a continuous drive to reduce operating costs, particularly in a climate of weak oil prices. These factors have led to a dramatic increase in diversity and volume of coiled tubing interventions. In the following article, coiled tubing interventions, and results of those interventions, are discussed. An assessment of future coiled tubing activity on Magnus field is provided.

  12. Bow-shaped toroidal field coils

    SciTech Connect

    Bonanos, P.

    1981-05-01

    Design features of Bow-Shaped Toroidal Field Coils are described and compared with circular and D shaped coils. The results indicate that bow coils can produce higher field strengths, store more energy and be made demountable. The design offers the potential for the production of ultrahigh toroidal fields. Included are representative coil shapes and their engineering properties, a suggested structural design and an analysis of a specific case.

  13. Multi-Canted Coils, Tubes, and Structures

    NASA Technical Reports Server (NTRS)

    Jaster, Mark L. (Inventor)

    2015-01-01

    Coil, tube, and other structures configured with a plurality of individual coils, internal structures, legs or extensions with each having multiple cants per coil, internal structure, leg or extension, and wherein the cants formed therein allow for a load-deflection force when each is compressed. In addition, any horizontal or moment forces are substantially reduced and/or eliminated when a downward vertical force is applied, as minimal or no torsion is created in the individual coils, legs or extensions.

  14. Novel TMS coils designed using an inverse boundary element method

    NASA Astrophysics Data System (ADS)

    Cobos Sánchez, Clemente; María Guerrero Rodriguez, Jose; Quirós Olozábal, Ángel; Blanco-Navarro, David

    2017-01-01

    In this work, a new method to design TMS coils is presented. It is based on the inclusion of the concept of stream function of a quasi-static electric current into a boundary element method. The proposed TMS coil design approach is a powerful technique to produce stimulators of arbitrary shape, and remarkably versatile as it permits the prototyping of many different performance requirements and constraints. To illustrate the power of this approach, it has been used for the design of TMS coils wound on rectangular flat, spherical and hemispherical surfaces, subjected to different constraints, such as minimum stored magnetic energy or power dissipation. The performances of such coils have been additionally described; and the torque experienced by each stimulator in the presence of a main magnetic static field have theoretically found in order to study the prospect of using them to perform TMS and fMRI concurrently. The obtained results show that described method is an efficient tool for the design of TMS stimulators, which can be applied to a wide range of coil geometries and performance requirements.

  15. Experimental and numerical study on unsteady natural convection heat transfer in helically coiled tube heat exchangers

    NASA Astrophysics Data System (ADS)

    Neshat, E.; Hossainpour, S.; Bahiraee, F.

    2014-06-01

    Both of experimental and numerical investigations were performed to understand unsteady natural convection from outer surface of helical coils. Four helical coils with two different curvature ratios were used. Each coil was mounted in the shell both vertically and horizontally. The cold water was entered the coil and the hot water in the shell was cooling by unsteady natural convection. A CFD code was developed to simulate natural convection heat transfer. Equations of tube and shell are solved simultaneously. Statistical analyses have been done on data points of temperature and natural convection Nusselt number. It was revealed that shell-side fluid temperature and the Nusselt number of the outer surface of coils are functions of in-tube fluid mass flow rate, specific heat of fluids and geometrical parameters including length, inner diameter of the tube and the volume of the shell, and time.

  16. Perspective methods for the generation of COIL gain medium

    NASA Astrophysics Data System (ADS)

    Zagidullin, Marsel V.; Nikolaev, Valery D.; Svistun, Michael I.; Khvatov, Nikolay A.

    2007-04-01

    An ejector nozzle bank powered by centrifugal bubbling SOG is considered like highly efficient gain generating system for COIL. A high potential recovered pressure ~100 torr of the gain medium flow with a small signal gain higher than 1% cm -1 and low oxygen plenum pressure has been demonstrated. A centrifugal bubbling SOG is an efficient source of oxygen at high pressure with high depletion of the BHP in the single burn dawn. A high 0 II(1Δ) yield and chlorine utilization higher than 90% have been obtained at chlorine gas loading up to 6 mmole/s per 1 cm2 of the bubbler surface. The ejector COIL powered by centrifugal bubbling SOG demonstrated ~25% of chemical efficiency with specific power 6 kJ per 1 litre of the BHP in the single burn dawn. The combination of centrifugal bubble SOG with ejector nozzle bank can be considered as a promising gain medium flow generation system for COIL.

  17. Miniature coils for producing pulsed inplane magnetic fields for nanospintronics

    SciTech Connect

    Pawliszak, Łukasz; Zgirski, Maciej

    2015-03-15

    Nanospintronic and related research often requires the application of quickly rising magnetic field pulses in the plane of the studied planar structure. We have designed and fabricated sub-millimeter-sized coils capable of delivering pulses of the magnetic field up to ∼500 Oe in the plane of the sample with the rise time of the order of 10 ns. The placement of the sample above the coil allows for easy access to its surface with manipulators or light beams for, e.g., Kerr microscopy. We use the fabricated coil to drive magnetic domain walls in 1 μm wide permalloy wires and measure magnetic domain wall velocity as a function of the applied magnetic field.

  18. Hyperglycemia and Diabetes Downregulate the Functional Expression of TRPV4 Channels in Retinal Microvascular Endothelium

    PubMed Central

    Monaghan, Kevin; McNaughten, Jennifer; McGahon, Mary K.; Kelly, Catriona; Kyle, Daniel; Yong, Phaik Har

    2015-01-01

    Retinal endothelial cell dysfunction is believed to play a key role in the etiology and pathogenesis of diabetic retinopathy. Numerous studies have shown that TRPV4 channels are critically involved in maintaining normal endothelial cell function. In the current paper, we demonstrate that TRPV4 is functionally expressed in the endothelium of the retinal microcirculation and that both channel expression and activity is downregulated by hyperglycaemia. Quantitative PCR and immunostaining demonstrated molecular expression of TRPV4 in cultured bovine retinal microvascular endothelial cells (RMECs). Functional TRPV4 activity was assessed in cultured RMECs from endothelial Ca2+-responses recorded using fura-2 microfluorimetry and electrophysiological recordings of membrane currents. The TRPV4 agonist 4α-phorbol 12,13-didecanoate (4-αPDD) increased [Ca2+]i in RMECs and this response was largely abolished using siRNA targeted against TRPV4. These Ca2+-signals were completely inhibited by removal of extracellular Ca2+, confirming their dependence on influx of extracellular Ca2+. The 4-αPDD Ca2+-response recorded in the presence of cyclopiazonic acid (CPA), which depletes the intracellular stores preventing any signal amplification through store release, was used as a measure of Ca2+-influx across the cell membrane. This response was blocked by HC067047, a TRPV4 antagonist. Under voltage clamp conditions, the TRPV4 agonist GSK1016790A stimulated a membrane current, which was again inhibited by HC067047. Following incubation with 25mM D-glucose TRPV4 expression was reduced in comparison with RMECs cultured under control conditions, as were 4αPDD-induced Ca2+-responses in the presence of CPA and ion currents evoked by GSK1016790A. Molecular expression of TRPV4 in the retinal vascular endothelium of 3 months’ streptozotocin-induced diabetic rats was also reduced in comparison with that in age-matched controls. We conclude that hyperglycaemia and diabetes reduce the

  19. Split Coil Forms for Rotary Transformers

    NASA Technical Reports Server (NTRS)

    Mclyman, C. W. T.

    1982-01-01

    Split cores for rotor and stator windings of rotary transformer mounted around their respective coils (which are in bobbins) and cemented together. This arrangement simplifies winding of stator coil to go in a slot in inner diameter of stator coil. One practical application of rotary transformers fabricated according to this technique is for centrifuges, in which conventional sliprings are of uncertain reliability.

  20. Inductively coupled wireless RF coil arrays.

    PubMed

    Bulumulla, S B; Fiveland, E; Park, K J; Foo, T K; Hardy, C J

    2015-04-01

    As the number of coils increases in multi-channel MRI receiver-coil arrays, RF cables and connectors become increasingly bulky and heavy, degrading patient comfort and slowing workflow. Inductive coupling of signals provides an attractive "wireless" approach, with the potential to reduce coil weight and cost while simplifying patient setup. In this work, multi-channel inductively coupled anterior arrays were developed and characterized for 1.5T imaging. These comprised MR receiver coils inductively (or "wirelessly") linked to secondary or "sniffer" coils whose outputs were transmitted via preamps to the MR system cabinet. The induced currents in the imaging coils were blocked by passive diode circuits during RF transmit. The imaging arrays were totally passive, obviating the need to deliver power to the coils, and providing lightweight, untethered signal reception with easily positioned coils. Single-shot fast spin echo images were acquired from 5 volunteers using a 7-element inductively coupled coil array and a conventionally cabled 7-element coil array of identical geometry, with the inductively-coupled array showing a relative signal-to-noise ratio of 0.86 +/- 0.07. The concept was extended to a larger 9-element coil array to demonstrate the effect of coil element size on signal transfer and RF-transmit blocking.

  1. A dual-tuned transceive resonator for (13) C{(1) H} MRS: two open coils in one.

    PubMed

    Yahya, Atiyah; De Zanche, Nicola; Allen, Peter S

    2013-05-01

    Proton-decoupled, (13) C nuclear MRS experiments require a RF coil that operates at the Larmor frequencies of both (13) C and (1) H. In this work, we designed, built and tested a single-unit, dual-tuned coil based on a half-birdcage open coil design. It was constructed as a low-pass network with a resonant trap in series with each leg. Traps are tuned in alternate legs such that the two resonant modes arise from currents on alternate legs. The coil performance was compared with that of a dual-tuned coil consisting of two proton surface coils operating in quadrature and a single surface coil for (13) C transmission and reception. The half-birdcage coil was shown to produce a more homogeneous RF field at each frequency and was more sensitive to a (13) C signal arising from regions further from the coil surface. The applicability of the coil in vivo was demonstrated by acquiring a proton decoupled, natural abundance (13) C glycogen signal from the calf of a normal volunteer.

  2. Repeats in transforming acidic coiled-coil (TACC) genes.

    PubMed

    Trivedi, Seema

    2013-06-01

    Transforming acidic coiled-coil proteins (TACC1, 2, and 3) are essential proteins associated with the assembly of spindle microtubules and maintenance of bipolarity. Dysregulation of TACCs is associated with tumorigenesis, but studies of microsatellite instability in TACC genes have not been extensive. Microsatellite or simple sequence repeat instability is known to cause many types of cancer. The present in silico analysis of SSRs in human TACC gene sequences shows the presence of mono- to hexa-nucleotide repeats, with the highest densities found for mono- and di-nucleotide repeats. Density of repeats is higher in introns than in exons. Some of the repeats are present in regulatory regions and retained introns. Human TACC genes show conservation of many repeat classes. Microsatellites in TACC genes could be valuable markers for monitoring numerical chromosomal aberrations and or cancer.

  3. Feasibility and repeatability of localized 31P‐MRS four‐angle saturation transfer (FAST) of the human gastrocnemius muscle using a surface coil at 7 T

    PubMed Central

    Tušek Jelenc, Marjeta; Chmelík, Marek; Bogner, Wolfgang; Krššák, Martin; Trattnig, Siegfried

    2016-01-01

    Phosphorus (31P) MRS, combined with saturation transfer (ST), provides non‐invasive insight into muscle energy metabolism. However, even at 7 T, the standard ST method with T 1 app measured by inversion recovery takes about 10 min, making it impractical for dynamic examinations. An alternative method, i.e. four‐angle saturation transfer (FAST), can shorten the examination time. The aim of this study was to test the feasibility, repeatability, and possible time resolution of the localized FAST technique measurement on an ultra‐high‐field MR system, to accelerate the measurement of both Pi‐to‐ATP and PCr‐to‐ATP reaction rates in the human gastrocnemius muscle and to test the feasibility of using the FAST method for dynamic measurements. We measured the exchange rates and metabolic fluxes in the gastrocnemius muscle of eight healthy subjects at 7 T with the depth‐resolved surface coil MRS (DRESS)‐localized FAST method. For comparison, a standard ST localized method was also used. The measurement time for the localized FAST experiment was 3.5 min compared with the 10 min for the standard localized ST experiment. In addition, in five healthy volunteers, Pi‐to‐ATP and PCr‐to‐ATP metabolic fluxes were measured in the gastrocnemius muscle at rest and during plantar flexion by the DRESS‐localized FAST method. The repeatability of PCr‐to‐ATP and Pi‐to‐ATP exchange rate constants, determined by the slab‐selective localized FAST method at 7 T, is high, as the coefficients of variation remained below 20%, and the results of the exchange rates measured with the FAST method are comparable to those measured with standard ST. During physical activity, the PCr‐to‐ATP metabolic flux decreased (from F CK = 8.21 ± 1.15 mM s−1 to F CK = 3.86 ± 1.38 mM s−1) and the Pi‐to‐ATP flux increased (from F ATP = 0.43 ± 0.14 mM s−1 to F ATP = 0.74 ± 0.13 mM s−1). In conclusion

  4. The renal TRPV4 channel is essential for adaptation to increased dietary potassium.

    PubMed

    Mamenko, Mykola V; Boukelmoune, Nabila; Tomilin, Viktor N; Zaika, Oleg L; Jensen, V Behrana; O'Neil, Roger G; Pochynyuk, Oleh M

    2017-02-07

    To maintain potassium homeostasis, kidneys exert flow-dependent potassium secretion to facilitate kaliuresis in response to elevated dietary potassium intake. This process involves stimulation of calcium-activated large conductance maxi-K (BK) channels in the distal nephron, namely the connecting tubule and the collecting duct. Recent evidence suggests that the TRPV4 channel is a critical determinant of flow-dependent intracellular calcium elevations in these segments of the renal tubule. Here, we demonstrate that elevated dietary potassium intake (five percent potassium) increases renal TRPV4 mRNA and protein levels in an aldosterone-dependent manner and causes redistribution of the channel to the apical plasma membrane in native collecting duct cells. This, in turn, leads to augmented TRPV4-mediated flow-dependent calcium ion responses in freshly isolated split-opened collecting ducts from mice fed the high potassium diet. Genetic TRPV4 ablation greatly diminished BK channel activity in collecting duct cells pointing to a reduced capacity to excrete potassium. Consistently, elevated potassium intake induced hyperkalemia in TRPV4 knockout mice due to deficient renal potassium excretion. Thus, regulation of TRPV4 activity in the distal nephron by dietary potassium is an indispensable component of whole body potassium balance.

  5. Transient receptor potential melastatin 4 channel contributes to migration of androgen-insensitive prostate cancer cells

    PubMed Central

    Kilch, Tatiana; Jochum, Marcus Martin; Urban, Sabine Katharina; Jung, Volker; Stöckle, Michael; Rother, Karen; Greiner, Markus; Peinelt, Christine

    2015-01-01

    Impaired Ca2+ signaling in prostate cancer contributes to several cancer hallmarks, such as enhanced proliferation and migration and a decreased ability to induce apoptosis. Na+ influx via transient receptor potential melastatin 4 channel (TRPM4) can reduce store-operated Ca2+ entry (SOCE) by decreasing the driving force for Ca2+. In patients with prostate cancer, gene expression of TRPM4 is elevated. Recently, TRPM4 was identified as a cancer driver gene in androgen-insensitive prostate cancer. We investigated TRPM4 protein expression in cancer tissue samples from 20 patients with prostate cancer. We found elevated TRPM4 protein levels in prostatic intraepithelial neoplasia (PIN) and prostate cancer tissue compared to healthy tissue. In primary human prostate epithelial cells (hPEC) from healthy tissue and in the androgen-insensitive prostate cancer cell lines DU145 and PC3, TRPM4 mediated large Na+ currents. We demonstrated significantly increased SOCE after siRNA targeting of TRPM4 in hPEC and DU145 cells. In addition, knockdown of TRPM4 reduced migration but not proliferation of DU145 and PC3 cells. Taken together, our data identify TRPM4 as a regulator of SOCE in hPEC and DU145 cells, demonstrate a role for TRPM4 in cancer cell migration and suggest that TRPM4 is a promising potential therapeutic target. PMID:26496025

  6. TRPV4 channel is involved in the coupling of fluid viscosity changes to epithelial ciliary activity

    PubMed Central

    Andrade, Yaniré N.; Fernandes, Jacqueline; Vázquez, Esther; Fernández-Fernández, José M.; Arniges, Maite; Sánchez, Trinidad M.; Villalón, Manuel; Valverde, Miguel A.

    2005-01-01

    Autoregulation of the ciliary beat frequency (CBF) has been proposed as the mechanism used by epithelial ciliated cells to maintain the CBF and prevent the collapse of mucociliary transport under conditions of varying mucus viscosity. Despite the relevance of this regulatory response to the pathophysiology of airways and reproductive tract, the underlying cellular and molecular aspects remain unknown. Hamster oviductal ciliated cells express the transient receptor potential vanilloid 4 (TRPV4) channel, which is activated by increased viscous load involving a phospholipase A2–dependent pathway. TRPV4-transfected HeLa cells also increased their cationic currents in response to high viscous load. This mechanical activation is prevented in native ciliated cells loaded with a TRPV4 antibody. Application of the TRPV4 synthetic ligand 4α-phorbol 12,13-didecanoate increased cationic currents, intracellular Ca2+, and the CBF in the absence of a viscous load. Therefore, TRPV4 emerges as a candidate to participate in the coupling of fluid viscosity changes to the generation of the Ca2+ signal required for the autoregulation of CBF. PMID:15753126

  7. Array high-sensitivity room temperature coil system for SNMR detection in shallow depth

    NASA Astrophysics Data System (ADS)

    Lin, Tingting; Xie, Kunyu; Zhang, Siyuan; Zhao, Jing; Lin, Jun

    2017-01-01

    The noninvasive method of surface nuclear magnetic resonance (SNMR) is a geophysical technique that is directly sensitive to hydrogen protons, besides it can exploit the NMR phenomenon for a quantitative determination of the subsurface groundwater distribution. Traditionally, SNMR utilizes large surface coils for both transmitting excitation pulses and recording the groundwater response. While, in recent research, a low Tc-SQUIDs is taken as a new sensor to replace the large receiving coil (Rx), which performing the best sensitivity for the shallow depth. Nevertheless, SQUID is with the problems of flux trapping and operational difficulties. In this paper, we introduce a room temperature coil system. A Cu coil with diameter of 1 m and a low noise preamplifier was systematically investigated and reached a sensitivity of 0.2fT/Hz1/2.Four preamplifiers are chosen for optimizing the pickup coils. The resolution studies for the array coil systems were performed, and the optimum distance between the adjacent pickup coils to achieve a better experimental results especially for the shallow depth. Our study enable the further use of the room temperature coil for SNMR shallow depth detections.

  8. Normal conducting transfer coil for SQUID NDE

    NASA Astrophysics Data System (ADS)

    Kondo, Tadayuki; Itozaki, Hideo

    2004-03-01

    We have investigated the performance of a normal conducting transfer coil (n-coil) for nondestructive evaluation with a SQUID. The transfer efficiency, which depends on frequency and wire impedance, has been calculated for several coil designs to determine the performance of the n-coil. We have fabricated a 30 mm diameter n-coil and examined its performance with a high-TC SQUID. If both the pick-up coil and the input coil have 50 turns, then at high frequencies the magnetic field produced by the input coil becomes 50% of the magnetic field at the pick-up coil, with a low cut-off frequency of 2 kHz. The experimental result agrees well with a numerical calculation, which suggests a magnitude of magnetic field detected by our SQUID equal to the magnitude of the quasi-uniform magnetic field produced by the input coil. We also confirmed that the thermal noise of the n-coil, produced by its normal resistance, does not become higher than the intrinsic magnetic field noise of the SQUID.

  9. Starch gelatinization in coiled heaters.

    PubMed

    Kelder, J D H; Ptasinski, K J; Kerkhof, P J A M

    2004-01-01

    A gelatinizing model food derived from a 5% w/w cross-linked waxy maize starch suspension was simulated in coiled heaters to assess the impact of centrifugal forces on flow and heat transfer. For four coil diameters (D = 0.25, 1, 2.5, and infinity m) and three flow rates (w = 0.5, 1, and 2 m/s), heat transfer, viscous development, and the severity of channeling were evaluated. Increasing curvature proved to suppress channeling as a result of more uniform heating and gelatinization. The maximum attainable viscosity was also higher, implying a lower starch consumption for a target viscosity. Higher flow rates necessitated longer heaters, and the maximum viscosity decreased. Moderate product velocities are therefore recommended.

  10. Three-dimensional coil inductor

    DOEpatents

    Bernhardt, Anthony F.; Malba, Vincent

    2002-01-01

    A three-dimensional coil inductor is disclosed. The inductor includes a substrate; a set of lower electrically conductive traces positioned on the substrate; a core placed over the lower traces; a set of side electrically conductive traces laid on the core and the lower traces; and a set of upper electrically conductive traces attached to the side traces so as to form the inductor. Fabrication of the inductor includes the steps of forming a set of lower traces on a substrate; positioning a core over the lower traces; forming a set of side traces on the core; connecting the side traces to the lower traces; forming a set of upper traces on the core; and connecting the upper traces to the side traces so as to form a coil structure.

  11. Practical Aspects of Birdcage Coils

    NASA Astrophysics Data System (ADS)

    Doty, F. David; Entzminger, George; Hauck, Cory D.; Staab, John P.

    1999-05-01

    Numerical modeling and experimental results are presented for a variety of birdcages for high-field MRI microscopy. The data include the first published numerical calculations and experimental measurements of magnetic filling factors of birdcages or other MRI coils. Fast, 3D calculations for shielded coils are demonstrated using the Biot-Savart law along with energy minimization. It is shown that the near-field, higher-order inhomogeneity effects remaining after a first-order, asymmetry correction may easily exceed 20% in situations where it is desirable to maximize filling factor. It is also found that an order-of-magnitude improvement in the accuracy of predicted capacitor values may be achieved by using a more detailed circuit model of the birdcage resonator.

  12. Practical aspects of birdcage coils.

    PubMed

    Doty, F D; Entzminger, G; Hauck, C D; Staab, J P

    1999-05-01

    Numerical modeling and experimental results are presented for a variety of birdcages for high-field MRI microscopy. The data include the first published numerical calculations and experimental measurements of magnetic filling factors of birdcages or other MRI coils. Fast, 3D calculations for shielded coils are demonstrated using the Biot-Savart law along with energy minimization. It is shown that the near-field, higher-order inhomogeneity effects remaining after a first-order, asymmetry correction may easily exceed 20% in situations where it is desirable to maximize filling factor. It is also found that an order-of-magnitude improvement in the accuracy of predicted capacitor values may be achieved by using a more detailed circuit model of the birdcage resonator.

  13. Equations determine coiled tubing collapse pressure

    SciTech Connect

    Avakov, V.; Taliaferro, W.

    1995-07-24

    A set of equations has been developed for calculating pipe collapse pressure for oval tubing such as coiled tubing. When coiled tubing is placed onto a reel, the tubing is forced into an oval shape and never again returns to perfect roundness because the coiling process exceeds the plasticity limits of the tubing. Straightening the tubing for the trip into the well does not restore roundness. The consequence of this physical property is that all coiled tubing collapse pressure calculations should be made considering oval tubing, not round tubing. Tubing collapse can occur when formation pressure against the coiled tubing exceeds the collapse resistance inherent in the coiled tubing. As coiled tubing becomes more oval in shape, it becomes more oval in shape, it becomes more susceptible to collapse from outside pressure.

  14. Rectangular coils optimization for wireless power transmission

    NASA Astrophysics Data System (ADS)

    Duan, Zhu; Guo, Yong-Xin; Kwong, Dim-Lee

    2012-01-01

    Wirelessly coupled coils are crucial for efficient power transmission in various applications. Previous design methods are only eligible for improving the efficiency of circular or square coils. This paper presents a method of characterizing and optimizing rectangular coils used in inductively coupled systems. After setting up a lumped component model for inductive coils, the efficiency can be expressed in terms of geometrical parameters of the coils. Subsequently, the power efficiency can be plotted versus these parameters in Matlab, thus getting the desired coils for optimum power transfer. With this design procedure from mathematical optimization, we eventually designed two rectangular coils spaced 10 mm apart, which achieves a power transmission efficiency of 46.4% at a frequency of 3 MHz. The design methodology is verified by simulation and measurement.

  15. Segmented Coil Fails In Steps

    NASA Technical Reports Server (NTRS)

    Stedman, Ronald S.

    1990-01-01

    Electromagnetic coil degrades in steps when faults occur, continues to operate at reduced level instead of failing catastrophically. Made in segments connected in series and separated by electrically insulating barriers. Fault does not damage adjacent components or create hazard. Used to control valves in such critical applications as cooling systems of power generators and chemical process equipment, where flammable liquids or gases handled. Also adapts to electrical control of motors.

  16. Coiled transmission line pulse generators

    DOEpatents

    McDonald, Kenneth Fox

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  17. Pharmacological inhibitors of TRPV4 channels reduce cytokine production, restore endothelial function and increase survival in septic mice

    PubMed Central

    Dalsgaard, Thomas; Sonkusare, Swapnil K.; Teuscher, Cory; Poynter, Matthew E.; Nelson, Mark T.

    2016-01-01

    Sepsis is characterized by systemic inflammation, edema formation and hypo-perfusion leading to organ dysfunction and ultimately death. Activation of the transient receptor potential vanilloid type 4 (TRPV4) channel is associated with edema formation and circulatory collapse. Here, we show that TRPV4 channels are involved in the hyper-inflammatory response and mortality associated with sepsis. Pharmacological inhibition of TRPV4 channels in mice reduced mortality in lipopolysaccharide and cecal-ligation-and-puncture models of sepsis, but not in a tumor necrosis factor-α (TNFα)-induced sepsis model. These protective effects of TRPV4 channel inhibition were attributable to prevention of the sepsis-induced surge of a broad spectrum of pro-inflammatory cytokines, including TNFα, interleukin (IL)-1 and IL-6, and subsequent preservation of endothelial cell function, including Ca2+ signaling, integrity and endothelium-dependent vasodilation. These results suggest that TRPV4 antagonists may be of therapeutic utility in the management of sepsis. PMID:27653046

  18. Mefloquine inhibits voltage dependent Nav1.4 channel by overlapping the local anaesthetic binding site.

    PubMed

    Paiz-Candia, Bertin; Islas, Angel A; Sánchez-Solano, Alfredo; Mancilla-Simbro, Claudia; Scior, Thomas; Millan-PerezPeña, Lourdes; Salinas-Stefanon, Eduardo M

    2017-02-05

    Mefloquine constitutes a multitarget antimalaric that inhibits cation currents. However, the effect and the binding site of this compound on Na(+) channels is unknown. To address the mechanism of action of mefloquine, we employed two-electrode voltage clamp recordings on Xenopus laevis oocytes, site-directed mutagenesis of the rat Na(+) channel, and a combined in silico approach using Molecular Dynamics and docking protocols. We found that mefloquine: i) inhibited Nav1.4 currents (IC50 =60μM), ii) significantly delayed fast inactivation but did not affect recovery from inactivation, iii) markedly the shifted steady-state inactivation curve to more hyperpolarized potentials. The presence of the β1 subunit significantly reduced mefloquine potency, but the drug induced a significant frequency-independent rundown upon repetitive depolarisations. Computational and experimental results indicate that mefloquine overlaps the local anaesthetic binding site by docking at a hydrophobic cavity between domains DIII and DIV that communicates the local anaesthetic binding site with the selectivity filter. This is supported by the fact that mefloquine potency significantly decreased on mutant Nav1.4 channel F1579A and significantly increased on K1237S channels. In silico this compound docked above F1579 forming stable π-π interactions with this residue. We provide structure-activity insights into how cationic amphiphilic compounds may exert inhibitory effects by docking between the local anaesthetic binding site and the selectivity filter of a mammalian Na(+) channel. Our proposed synergistic cycle of experimental and computational studies may be useful for elucidating binding sites of other drugs, thereby saving in vitro and in silico resources.

  19. A comparison of coupling efficiencies for a Stix coil and an m equals 1 coil

    NASA Technical Reports Server (NTRS)

    Sigman, D. R.

    1972-01-01

    This theoretical and experimental study compares the ion-cyclotron wave generating characteristics of a Stix coil (which generates waves with azimuthal mode number m = 0) with those of a coil which produces primarily m = + or -1 ion-cyclotron modes. The theoretical work of J.E. Hipp, which predicted very good coupling for the m = 1 coil, was extended to determine the scaling laws for plasma column radius and coil wavelength. Experimentally, an m = 1 coil and an m = 0 coil were used to generate ion-cyclotron waves on a beam generated plasma column with electron density = 10 to the 12th power/cu cm. Coupling resonances with peak efficiencies of approximately 40 to 50 percent were measured for both coils in low power (approximately 10k W) experiments. For equal power transfer to the plasma, the m = 0 coil voltage was more than a factor of two greater than that for the m = 1 coil.

  20. Design, fabrication, and testing of the pulse coils for the Large Coil Test Facility

    SciTech Connect

    Chipley, K.K.; Parrelli, A.P.

    1983-01-01

    The Large Coil Test Facility (LCTF) will be able to test up to six large superconducting coils similar to those required for a tokamak reactor. In order to simulate the transient vertical field that will be part of the magnetic environment of an operating tokamak reactor, a set of pulse coils will be used in the facility. This set of two coils can be positioned in the bore of any of the test coils to provide a transient magnetic field to that particular coil. This paper describes the final design of the pulse coils and discusses the fabrication techniques used to build these coils. An extensive testing program has been carried out during fabrication to ensure that the coils will function satisfactorily.

  1. A Mechanical Coil Insertion System for Endovascular Coil Embolization of Intracranial Aneurysms

    PubMed Central

    Haraguchi, K.; Miyachi, S.; Matsubara, N.; Nagano, Y.; Yamada, H.; Marui, N.; Sano, A.; Fujimoto, H.; Izumi, T.; Yamanouchi, T.; Asai, T.; Wakabayashi, T.

    2013-01-01

    Summary Like other fields of medicine, robotics and mechanization might be introduced into endovascular coil embolization of intracranial aneurysms for effective treatment. We have already reported that coil insertion force could be smaller and more stable when the coil delivery wire is driven mechanically at a constant speed. Another background is the difficulty in synchronizing operators' minds and hands when two operators control the microcatheter and the coil respectively. We have therefore developed a mechanical coil insertion system enabling a single operator to insert coils at a fixed speed while controlling the microcatheter. Using our new system, the operator manipulated the microcatheter with both hands and drove the coil using foot switches simultaneously. A delivery wire force sensor previously reported was used concurrently, allowing the operator to detect excessive stress on the wire. In vitro coil embolization was performed using three methods: simple mechanical advance of the coil; simple mechanical advance of the coil with microcatheter control; and driving (forward and backward) of the coil using foot switches in addition to microcatheter control. The system worked without any problems, and did not interfere with any procedures. In experimental coil embolization, delivery wire control using the foot switches as well as microcatheter manipulation helped to achieve successful insertion of coils. This system could offer the possibility of developing safer and more efficient coil embolization. Although we aim at total mechanization and automation of procedures in the future, microcatheter manipulation and synchronized delivery wire control are still indispensable using this system. PMID:23693038

  2. E-coil: an inverse boundary element method for a quasi-static problem.

    PubMed

    Sanchez, Clemente Cobos; Garcia, Salvador Gonzalez; Power, Henry

    2010-06-07

    Boundary element methods represent a valuable approach for designing gradient coils; these methods are based on meshing the current carrying surface into an array of boundary elements. The temporally varying magnetic fields produced by gradient coils induce electric currents in conducting tissues and so the exposure of human subjects to these magnetic fields has become a safety concern, especially with the increase in the strength of the field gradients used in magnetic resonance imaging. Here we present a boundary element method for the design of coils that minimize the electric field induced in prescribed conducting systems. This work also details some numerical examples of the application of this coil design method. The reduction of the electric field induced in a prescribed region inside the coils is also evaluated.

  3. Optically detunable, inductively coupled coil for self-gating in small animal magnetic resonance imaging.

    PubMed

    Korn, Matthias; Umathum, Reiner; Schulz, Jessica; Semmler, Wolfhard; Bock, Michael

    2011-03-01

    An inductively coupled coil concept is presented, which improves the compensation of physiological motion by the self-gating (SG) technique. The animal is positioned in a conventional volume coil encompassing the whole animal. A small, resonant surface coil (SG-coil) is placed on the thorax so that its sensitive region includes the heart. Via inductive coupling the SG-coil amplifies selectively the MR signal of the beating heart. With an optical detuning mechanism, this coupling can be switched off during acquisition of the MR image information, whereas it is active during SG data sampling to provide the physiological information. In vivo experiments on a mouse show an amplification of the SG signal by at least 40%.

  4. Optimized Geometry for Superconducting Sensing Coils

    NASA Technical Reports Server (NTRS)

    Eom, Byeong Ho; Pananen, Konstantin; Hahn, Inseob

    2008-01-01

    An optimized geometry has been proposed for superconducting sensing coils that are used in conjunction with superconducting quantum interference devices (SQUIDs) in magnetic resonance imaging (MRI), magnetoencephalography (MEG), and related applications in which magnetic fields of small dipoles are detected. In designing a coil of this type, as in designing other sensing coils, one seeks to maximize the sensitivity of the detector of which the coil is a part, subject to geometric constraints arising from the proximity of other required equipment. In MRI or MEG, the main benefit of maximizing the sensitivity would be to enable minimization of measurement time. In general, to maximize the sensitivity of a detector based on a sensing coil coupled with a SQUID sensor, it is necessary to maximize the magnetic flux enclosed by the sensing coil while minimizing the self-inductance of this coil. Simply making the coil larger may increase its self-inductance and does not necessarily increase sensitivity because it also effectively increases the distance from the sample that contains the source of the signal that one seeks to detect. Additional constraints on the size and shape of the coil and on the distance from the sample arise from the fact that the sample is at room temperature but the coil and the SQUID sensor must be enclosed within a cryogenic shield to maintain superconductivity.

  5. Crystal structure of cytomegalovirus IE1 protein reveals targeting of TRIM family member PML via coiled-coil interactions.

    PubMed

    Scherer, Myriam; Klingl, Stefan; Sevvana, Madhumati; Otto, Victoria; Schilling, Eva-Maria; Stump, Joachim D; Müller, Regina; Reuter, Nina; Sticht, Heinrich; Muller, Yves A; Stamminger, Thomas

    2014-11-01

    PML nuclear bodies (PML-NBs) are enigmatic structures of the cell nucleus that act as key mediators of intrinsic immunity against viral pathogens. PML itself is a member of the E3-ligase TRIM family of proteins that regulates a variety of innate immune signaling pathways. Consequently, viruses have evolved effector proteins to modify PML-NBs; however, little is known concerning structure-function relationships of viral antagonists. The herpesvirus human cytomegalovirus (HCMV) expresses the abundant immediate-early protein IE1 that colocalizes with PML-NBs and induces their dispersal, which correlates with the antagonization of NB-mediated intrinsic immunity. Here, we delineate the molecular basis for this antagonization by presenting the first crystal structure for the evolutionary conserved primate cytomegalovirus IE1 proteins. We show that IE1 consists of a globular core (IE1CORE) flanked by intrinsically disordered regions. The 2.3 Å crystal structure of IE1CORE displays an all α-helical, femur-shaped fold, which lacks overall fold similarity with known protein structures, but shares secondary structure features recently observed in the coiled-coil domain of TRIM proteins. Yeast two-hybrid and coimmunoprecipitation experiments demonstrate that IE1CORE binds efficiently to the TRIM family member PML, and is able to induce PML deSUMOylation. Intriguingly, this results in the release of NB-associated proteins into the nucleoplasm, but not of PML itself. Importantly, we show that PML deSUMOylation by IE1CORE is sufficient to antagonize PML-NB-instituted intrinsic immunity. Moreover, co-immunoprecipitation experiments demonstrate that IE1CORE binds via the coiled-coil domain to PML and also interacts with TRIM5α We propose that IE1CORE sequesters PML and possibly other TRIM family members via structural mimicry using an extended binding surface formed by the coiled-coil region. This mode of interaction might render the antagonizing activity less susceptible to

  6. Electromagnetic levitation coil fabrication technique for MSFC containerless processing facilities

    NASA Technical Reports Server (NTRS)

    Ethridge, E. C.; Theiss, J.; Curreri, P. A.; Abbaschian, G. J.

    1983-01-01

    A technique is described for more reproducible fabrication of electromagnetic levitation coils. A split mandrel was developed upon which the coil is wound. After fabrication the mandrel can be disassembled to remove it from the coil. Previously, a full day was required to fabricate a levitation coil and the success rate for a functional coil was only 50 percent. About eight coils may be completed in one day using the technique developed and 95 percent of them are good levitation coils.

  7. Crystal Structure of a Super Leucine Zipper an Extended Two-Stranded Super Long Coiled Coil

    SciTech Connect

    J Diao

    2011-12-31

    Coiled coil is a ubiquitous structural motif in proteins, with two to seven alpha helices coiled together like the strands of a rope, and coiled coil folding and assembly is not completely understood. A GCN4 leucine zipper mutant with four mutations of K3A, D7A, Y17W, and H18N has been designed, and the crystal structure has been determined at 1.6 {angstrom} resolution. The peptide monomer shows a helix trunk with short curved N- and C-termini. In the crystal, two monomers cross in 35{sup o} and form an X-shaped dimer, and each X-shaped dimer is welded into the next one through sticky hydrophobic ends, thus forming an extended two-stranded, parallel, super long coiled coil rather than a discrete, two-helix coiled coil of the wild-type GCN4 leucine zipper. Leucine residues appear at every seventh position in the super long coiled coil, suggesting that it is an extended super leucine zipper. Compared to the wild-type leucine zipper, the N-terminus of the mutant has a dramatic conformational change and the C-terminus has one more residue Glu 32 determined. The mutant X-shaped dimer has a large crossing angle of 35{sup o} instead of 18{sup o} in the wild-type dimer. The results show a novel assembly mode and oligomeric state of coiled coil, and demonstrate that mutations may affect folding and assembly of the overall coiled coil. Analysis of the formation mechanism of the super long coiled coil may help understand and design self-assembling protein fibers.

  8. Critical evaluation of in silico methods for prediction of coiled-coil domains in proteins.

    PubMed

    Li, Chen; Ching Han Chang, Catherine; Nagel, Jeremy; Porebski, Benjamin T; Hayashida, Morihiro; Akutsu, Tatsuya; Song, Jiangning; Buckle, Ashley M

    2016-03-01

    Coiled-coils refer to a bundle of helices coiled together like strands of a rope. It has been estimated that nearly 3% of protein-encoding regions of genes harbour coiled-coil domains (CCDs). Experimental studies have confirmed that CCDs play a fundamental role in subcellular infrastructure and controlling trafficking of eukaryotic cells. Given the importance of coiled-coils, multiple bioinformatics tools have been developed to facilitate the systematic and high-throughput prediction of CCDs in proteins. In this article, we review and compare 12 sequence-based bioinformatics approaches and tools for coiled-coil prediction. These approaches can be categorized into two classes: coiled-coil detection and coiled-coil oligomeric state prediction. We evaluated and compared these methods in terms of their input/output, algorithm, prediction performance, validation methods and software utility. All the independent testing data sets are available at http://lightning.med.monash.edu/coiledcoil/. In addition, we conducted a case study of nine human polyglutamine (PolyQ) disease-related proteins and predicted CCDs and oligomeric states using various predictors. Prediction results for CCDs were highly variable among different predictors. Only two peptides from two proteins were confirmed to be CCDs by majority voting. Both domains were predicted to form dimeric coiled-coils using oligomeric state prediction. We anticipate that this comprehensive analysis will be an insightful resource for structural biologists with limited prior experience in bioinformatics tools, and for bioinformaticians who are interested in designing novel approaches for coiled-coil and its oligomeric state prediction.

  9. Optimum coil insertion speed of various coils in brain aneurysm embolization in vitro.

    PubMed

    Konishi, Yoshifumi; Takeuchi, Masataka; Fukasaku, Kazuaki

    2016-10-01

    A coil must comprise material with shape memory to perform optimal coil embolization. To achieve this, the alloy characteristics of the coil (hardness, shape, and thickness) must be understood. In this experiment, a catheter was fixed in the bright position and the movement of the coil was observed under a constant rate of insertion; the optimal insertion rate during clinical use was investigated. The first coil insertion speed was evaluated using simulated aneurysms in an in vivo arterial model. The results showed that the insertion force relates to the deployment shape of the coil, that the feedback through the force indicator using sound is very effective, and that the recorder is useful for analysis of coil embolization. The inserted coils during aneurysm embolization were able to wind uniformly within the aneurysm due to a variety of factors (guiding or micro-catheter position and kick-back phenomenon such as delivery wire). Optimal speed is achieved with proper coil design, which allows the coil to be inserted into the aneurysm. The shape and size of the aneurysm can help determine the necessary size and design of the coil that should be used during the optimal speed range. Aneurysm wall and coil characteristics are considered, along with the friction state of the coil (hardness, shape, and thickness), leading to improvements in safety during the insertion procedure at optimum speed.

  10. The Golgin Family of Coiled-Coil Tethering Proteins

    PubMed Central

    Witkos, Tomasz M.; Lowe, Martin

    2016-01-01

    The golgins are a family of predominantly coiled-coil proteins that are localized to the Golgi apparatus. Golgins are present in all eukaryotes, suggesting an evolutionary conserved function. Golgins are anchored to the Golgi membrane by their carboxy terminus and are predicted to adopt an extended conformation that projects into the surrounding cytoplasm. This arrangement is ideal for the capture or tethering of nearby membranes or cytoskeletal elements. Golgin-mediated tethering is thought to be important for vesicular traffic at the Golgi apparatus, the maintenance of Golgi architecture, as well as the positioning of the Golgi apparatus within cells. In addition to acting as tethers, some golgins can also sequester various factors at the Golgi membrane, allowing for the spatiotemporal regulation of downstream cellular functions. Although it is now established that golgins are membrane and cytoskeleton tethers, the mechanisms underlying tethering remain poorly defined. Moreover, the importance of golgin-mediated tethering in a physiological context remains to be fully explored. This review will describe our current understanding of golgin function, highlighting recent progress that has been made, and goes on to discuss outstanding questions and potential avenues for future research with regard to this family of conserved Golgi-associated proteins. PMID:26793708

  11. Unusually Stable Helical Coil Allotrope of Phosphorus.

    PubMed

    Liu, Dan; Guan, Jie; Jiang, Jingwei; Tománek, David

    2016-12-14

    We have identified an unusually stable helical coil allotrope of phosphorus. Our ab initio density functional theory calculations indicate that the uncoiled, isolated straight one-dimensional chain is equally stable as a monolayer of black phosphorus dubbed phosphorene. The coiling tendency and the attraction between adjacent coil segments add an extra stabilization energy of ∼12 meV/atom to the coil allotrope, similar in value to the ∼16 meV/atom interlayer attraction in bulk black phosphorus. Thus, the helical coil structure is essentially as stable as black phosphorus, the most stable phosphorus allotrope known to date. With an optimum radius of 2.4 nm, the helical coil of phosphorus may fit well and even form inside wide carbon nanotubes.

  12. The structure of the GemC1 coiled coil and its interaction with the Geminin family of coiled-coil proteins.

    PubMed

    Caillat, Christophe; Fish, Alexander; Pefani, Dafni Eleftheria; Taraviras, Stavros; Lygerou, Zoi; Perrakis, Anastassis

    2015-11-01

    GemC1, together with Idas and Geminin, an important regulator of DNA-replication licensing and differentiation decisions, constitute a superfamily sharing a homologous central coiled-coil domain. To better understand this family of proteins, the crystal structure of a GemC1 coiled-coil domain variant engineered for better solubility was determined to 2.2 Å resolution. GemC1 shows a less typical coiled coil compared with the Geminin homodimer and the Geminin-Idas heterodimer structures. It is also shown that both in vitro and in cells GemC1 interacts with Geminin through its coiled-coil domain, forming a heterodimer that is more stable that the GemC1 homodimer. Comparative analysis of the thermal stability of all of the possible superfamily complexes, using circular dichroism to follow the unfolding of the entire helix of the coiled coil, or intrinsic tryptophan fluorescence of a unique conserved N-terminal tryptophan, shows that the unfolding of the coiled coil is likely to take place from the C-terminus towards the N-terminus. It is also shown that homodimers show a single-state unfolding, while heterodimers show a two-state unfolding, suggesting that the dimer first falls apart and the helices then unfold according to the stability of each protein. The findings argue that Geminin-family members form homodimers and heterodimers between them, and this ability is likely to be important for modulating their function in cycling and differentiating cells.

  13. Comparison of birdcage and phase array coil using FDTD for the B(1) homogeneity in high field MRI.

    PubMed

    Seo, J H; Heo, H Y; Han, B H; Lee, S Y

    2007-01-01

    RF coils play an important role to acquire MR images with the maintenance of high homogeneity in high field MR system more than 3.0 T. Many kinds of RF coils such as birdcage coil, STR, surface coil, and phase array coil have been used, however, the good uniformity of a coil has always been an issue. In this paper, comparison of B(1) homogeneity between birdcage and phase array coil was investigated using FDTD method at 3.0 T MRI in order to develop RF coils with the high uniformity. Three different configurations of the FDTD simulation were performed like as using a free space configuration, water phantom configuration, and head mesh model. B1 homogeneity was calculated to the case of birdcage coil and 8-channel phase array coil in each configuration of simulation. Improvement on the homogeneity of the images and reduction of standing wave effect was achieved with comparing the real MR images with the result from simulation.

  14. Produce through coiled tubing to keep marginal wells unloaded

    SciTech Connect

    Not Available

    1986-12-01

    The use of coiled tubing as an alternate production tubing string has been attempted or considered by numerous operators in the past. However, its use has been tempered due to several problems known to be inherent with coiled tubing recompletions. Some of the problems encountered are: Killing the well to allow for tubing installation always carries the risk of formation damage; Candidate wells normally are marginal producers and may not produce sufficient revenue to justify the cost of a major workover; Procedures followed to install surface equipment may be hazardous; Previous installation designs required running the coiled tubing to the top of the tree, affecting the functional loss of all existing wellhead equipment; Often substandard modifications were required to reconnect into existing production facilities. However, a prototype spool and tubing hanger that incorporated modifications designed to solve these problems has been developed jointly by Reeled Tubing, Inc., and Well-head Control Systems. The solution is a new concept in the coiled tubing hanger. The design incorporates a floating element, which is a combination slip bowl, seal element and retaining sub. The entire assembly is installed and activated in the bore of a specially designed spool installed between the primary and secondary master valves of the existing wellhead.

  15. Horizontal underbalanced drilling of gas wells with coiled tubing

    SciTech Connect

    Cox, R.J.; Li, J.; Lupick, G.S.

    1999-03-01

    Coiled tubing drilling technology is gaining popularity and momentum as a significant and reliable method of drilling horizontal underbalanced wells. It is quickly moving into new frontiers. To this point, most efforts in the Western Canadian Basin have been focused towards sweet oil reservoirs in the 900--1300 m true vertical depth (TVD) range, however there is an ever-increasing interest in deeper and gas-producing formations. Significant design challenges on both conventional and coiled tubing drilling operations are imposed when attempting to drill these formations underbalanced. Coiled tubing is an ideal technology for underbalanced drilling due to its absence of drillstring connections resulting in continuous underbalanced capabilities. This also makes it suitable for sour well drilling and live well intervention without the risk of surface releases of reservoir gas. Through the use of pressure deployment procedures it is possible to complete the drilling operation without need to kill the well, thereby maintaining underbalanced conditions right through to the production phase. The use of coiled tubing also provides a means for continuous wireline communication with downhole steering, logging and pressure recording devices.

  16. Square Grains in Asymmetric Rod-Coil Block Copolymers

    SciTech Connect

    Olsen, B.D.; Toney, M.F.; Segalman, R.A.; /UC, Berkeley /LBL, Berkeley /SLAC, SSRL

    2009-04-30

    Unlike the rounded grains that are well known to form in most soft materials, square grains of microphase-separated lamellae are observed in thin films of a rod-coil block copolymer because of hierarchical structuring originating from the molecular packing of the rods. The square grains are oriented with lamellar layers parallel to the film interface and result from growth along orthogonal low-surface-energy directions as a result of the effects of the tetragonal crystalline lattice that forms within the rod-rich lamellar nanodomains of poly(2,5-di(2{prime}-ethylhexyloxy)-1,4-phenylene vinylene)-b-polyisoprene (PPV-b-PI). These grain shapes form only for a narrow range of coil volume fractions around 72% as a result of kinetic barriers at lower coil fractions and disordering of the lattice at higher coil fractions, and the polydisperse grain size suggests that growth is nucleation-limited. The grains form in both weakly and moderately segregated polymers at all annealing temperatures below the order-disorder transition, and they are observed for all thicknesses at which parallel-oriented grains are grown.

  17. Offset coil designs for superconducting magnets, a logical development

    SciTech Connect

    Collins, T.

    1986-03-01

    Dipoles and quadrupoles for any new, large proton ring must be stronger, smaller and have better field shape (systematic error) than those used in the Doubler. The present two-shell designs are rigid in that the coils are too thin but cannot be relatively fatter without destroying the field quality. An examination of the coil shapes for dipoles and quadrupoles which produce perfect fields from a uniform current density shows clearly that our persistent use of a circular form for the inner surface of the coils is a poor approximation. When this is corrected by ''offsets'' there is a striking improvement both in the strength of fields and in the field quality. The same analysis makes clear that the efficient use of superconductor and the overall magnet size is determined by the perfect coil shapes. Any reasonable magnet will not differ significantly from the ideal for these parameters. This will be particularly helpful in setting design goals for very large quadrupoles. The offset two-shell dipole design preserves the mechanical features of the highly successful, resilient doubler magnets while greatly extending the performance.

  18. Helical axis stellarator with noninterlocking planar coils

    DOEpatents

    Reiman, Allan; Boozer, Allen H.

    1987-01-01

    A helical axis stellarator using only noninterlocking planar, non-circular coils, generates magnetic fields having a magnetic well and large rotational transform with resultant large equilibrium beta.

  19. The intrinsic factor-vitamin B12 receptor, cubilin, is assembled into trimers via a coiled-coil alpha-helix.

    PubMed

    Lindblom, A; Quadt, N; Marsh, T; Aeschlimann, D; Mörgelin, M; Mann, K; Maurer, P; Paulsson, M

    1999-03-05

    A large protein was purified from bovine kidney, using selective extraction with EDTA to solubilize proteins anchored by divalent cation-dependent interactions. An antiserum raised against the purified protein labeled the apical cell surface of the epithelial cells in proximal tubules and the luminal surface of small intestine. Ten peptide sequences, derived from the protein, all matched the recently published sequences for rat (Moestrup, S. K., Kozyraki, R., Kristiansen, M., Kaysen, J. H., Holm Rasmussen, H., Brault, D., Pontillon, F., Goda, F. O., Christensen, E. I., Hammond, T. G., and Verroust, P. J. (1998) J. Biol. Chem. 273, 5235-5242) and human cubilin, a receptor for intrinsic factor-vitamin B12 complexes, identifying the protein as bovine cubilin. In electron microscopy, a three-armed structure was seen, indicating an oligomerization of three identical subunits. This model was supported by the Mr values of about 1,500,000 for the intact protein and 440,000 for its subunits obtained by analytical ultracentrifugation. In a search for a potential assembly domain, we identified a region of heptad repeats in the N-terminal part of the cubilin sequence. Computer-assisted analysis supported the presence of a coiled-coil alpha-helix between amino acids 103 and 132 of the human cubilin sequence and predicted the formation of a triple coiled-coil. We therefore conclude that cubilin forms a noncovalent trimer of identical subunits connected by an N-terminal coiled-coil alpha-helix.

  20. Note: High turn density magnetic coils with improved low pressure water cooling for use in atom optics

    SciTech Connect

    McKay Parry, Nicholas Neely, Tyler; Carey, Thomas; Bell, Thomas; Rubinsztein-Dunlop, Halina; Baker, Mark

    2014-08-15

    We describe a magnetic coil design utilizing concentrically wound electro-magnetic insulating (EMI) foil (25.4 μm Kapton backing and 127 μm thick layers). The magnetic coils are easily configurable for different coil sizes, while providing large surfaces for low-pressure (0.12 bar) water cooling. The coils have turn densities of ∼5 mm{sup −1} and achieve a maximum of 377 G at 2.1 kW driving power, measured at a distance 37.9 mm from the axial center of the coil. The coils achieve a steady-state temperature increase of 36.7°C/kW.

  1. Compact stellarators with modular coils.

    PubMed

    Garabedian, P R

    2000-07-18

    Compact stellarator designs with modular coils and only two or three field periods are now available; these designs have both good stability and quasiaxial symmetry providing adequate transport for a magnetic fusion reactor. If the bootstrap current assumes theoretically predicted values a three field period configuration is optimal, but if that net current turns out to be lower, a device with two periods and just 12 modular coils might be better. There are also attractive designs with quasihelical symmetry and four or five periods whose properties depend less on the bootstrap current. Good performance requires that there be a satisfactory magnetic well in the vacuum field, which is a property lacking in a stellarator-tokamak hybrid that has been proposed for a proof of principle experiment. In this paper, we present an analysis of stability for these configurations that is based on a mountain pass theorem asserting that, if two solutions of the problem of magnetohydrodynamic equilibrium can be found, then there has to be an unstable solution. We compare results of our theory of equilibrium, stability, and transport with recently announced measurements from the large LHD experiment in Japan.

  2. Compact stellarators with modular coils

    PubMed Central

    Garabedian, P. R.

    2000-01-01

    Compact stellarator designs with modular coils and only two or three field periods are now available; these designs have both good stability and quasiaxial symmetry providing adequate transport for a magnetic fusion reactor. If the bootstrap current assumes theoretically predicted values a three field period configuration is optimal, but if that net current turns out to be lower, a device with two periods and just 12 modular coils might be better. There are also attractive designs with quasihelical symmetry and four or five periods whose properties depend less on the bootstrap current. Good performance requires that there be a satisfactory magnetic well in the vacuum field, which is a property lacking in a stellarator-tokamak hybrid that has been proposed for a proof of principle experiment. In this paper, we present an analysis of stability for these configurations that is based on a mountain pass theorem asserting that, if two solutions of the problem of magnetohydrodynamic equilibrium can be found, then there has to be an unstable solution. We compare results of our theory of equilibrium, stability, and transport with recently announced measurements from the large LHD experiment in Japan. PMID:10899993

  3. Coiled tubing - Operations and services

    SciTech Connect

    Rich, D.A.; Blue, T.H. )

    1993-03-01

    Sand production can severely impact well performance and profitability by damaging production equipment or plugging wellbores. Sand control in existing wells may be required because of inadequate initial completion design, recompletion to new intervals or changes in reservoir production characteristics. The most durable and reliable sand control is by conventional gravel packing, but in some cases, conventional packs may not be economic or feasible. Improvements in coiled tubing technology and reliability have resulted in better application and increased acceptance of through-tubing sand control. Concentric gravel packing and sand consolidation are being used more because of advances in equipment, services, downhole tools and fluids. Candidates for these techniques include conventional completions that begin producing sand and wells with gravel pack failures. Economical jobs have been performed successfully in several different wellbore configurations. Some initially non-gravel packed wells are now being designed for possible through-tubing gravel packing, anticipating sand production later in the completion's producing life. This paper reviews the general procedures for installing a through-tubing, washdown mechanical gravel pack using coiled tubing conveyance and placement techniques.

  4. Accommodation of structural rearrangements in the huntingtin-interacting protein 1 coiled-coil domain

    SciTech Connect

    Wilbur, Jeremy D.; Hwang, Peter K.; Brodsky, Frances M.; Fletterick, Robert J.

    2010-03-01

    Variable packing interaction related to the conformational flexibility within the huntingtin-interacting protein 1 coiled coil domain. Huntingtin-interacting protein 1 (HIP1) is an important link between the actin cytoskeleton and clathrin-mediated endocytosis machinery. HIP1 has also been implicated in the pathogenesis of Huntington’s disease. The binding of HIP1 to actin is regulated through an interaction with clathrin light chain. Clathrin light chain binds to a flexible coiled-coil domain in HIP1 and induces a compact state that is refractory to actin binding. To understand the mechanism of this conformational regulation, a high-resolution crystal structure of a stable fragment from the HIP1 coiled-coil domain was determined. The flexibility of the HIP1 coiled-coil region was evident from its variation from a previously determined structure of a similar region. A hydrogen-bond network and changes in coiled-coil monomer interaction suggest that the HIP1 coiled-coil domain is uniquely suited to allow conformational flexibility.

  5. Visualization of an unstable coiled coil from the scallop myosin rod.

    PubMed

    Li, Yu; Brown, Jerry H; Reshetnikova, Ludmilla; Blazsek, Antal; Farkas, László; Nyitray, László; Cohen, Carolyn

    2003-07-17

    Alpha-helical coiled coils in muscle exemplify simplicity and economy of protein design: small variations in sequence lead to remarkable diversity in cellular functions. Myosin II is the key protein in muscle contraction, and the molecule's two-chain alpha-helical coiled-coil rod region--towards the carboxy terminus of the heavy chain--has unusual structural and dynamic features. The amino-terminal subfragment-2 (S2) domains of the rods can swing out from the thick filament backbone at a hinge in the coiled coil, allowing the two myosin 'heads' and their motor domains to interact with actin and generate tension. Most of the S2 rod appears to be a flexible coiled coil, but studies suggest that the structure at the N-terminal region is unstable, and unwinding or bending of the alpha-helices near the head-rod junction seems necessary for many of myosin's functional properties. Here we show the physical basis of a particularly weak coiled-coil segment by determining the 2.5-A-resolution crystal structure of a leucine-zipper-stabilized fragment of the scallop striated-muscle myosin rod adjacent to the head-rod junction. The N-terminal 14 residues are poorly ordered; the rest of the S2 segment forms a flexible coiled coil with poorly packed core residues. The unusual absence of interhelical salt bridges here exposes apolar core atoms to solvent.

  6. Statistical analysis of intrahelical ionic interactions in alpha-helices and coiled coils.

    PubMed

    Meier, Markus; Burkhard, Peter

    2006-08-01

    There are many controversies concerning whether ionic interactions in alpha-helices and coiled coils actually contribute to the stabilisation and formation of these structures. Here we used a statistical approach to probe this question. We extracted unique alpha-helical and coiled coil structures from the protein database and analysed the ionic interactions between positively and negatively charged residues. The ionic interactions were categorized according to the type, spacing and order of the residues involved. Separate datasets were produced depending on the number of alpha-helices in the coiled coils and the mutual orientation of the helices. We compared the frequency of residue configurations able to form ionic interactions with their probability to form the interaction. We found a correlation between the two variables in alpha-helices, antiparallel two-stranded coiled coils and parallel two-stranded coiled coils. This indicates that some ionic interactions are indeed important for the formation and stabilisation of alpha-helices and coiled coils. We concluded that the configurations, which have simultaneously a large probability to form the ionic interaction and a frequent occurrence, are those, which have the most stabilising effect. These are the 4RE, 3ER and 4ER interactions.

  7. Design of the coolant system for the Large Coil Test Facility pulse coils

    SciTech Connect

    Bridgman, C.; Ryan, T.L.

    1983-01-01

    The pulse coils will be a part of the Large Coil Test Facility in Oak Ridge, Tennessee, which is designed to test six large tokamak-type superconducting coils. The pulse coil set consists of two resistive coaxial solenoid coils, mounted so that their magnetic axis is perpendicular to the toroidal field lines of the test coil. The pulse coils provide transient vertical fields at test coil locations to simulate the pulsed vertical fields present in tokamak devices. The pulse coils are designed to be pulsed for 30 s every 150 s, which results in a Joule heating of 116 kW per coil. In order to provide this capability, the pulse coil coolant system is required to deliver 6.3 L/s (100 gpm) of subcooled liquid nitrogen at 10-atm absolute pressure. The coolant system can also cool down each pulse coil from room temperature to liquid nitrogen temperature. This paper provides details of the pumping and heat exchange equipment designed for the coolant system and of the associated instrumentation and controls.

  8. Kinin Receptors Sensitize TRPV4 Channel and Induce Mechanical Hyperalgesia: Relevance to Paclitaxel-Induced Peripheral Neuropathy in Mice.

    PubMed

    Costa, Robson; Bicca, Maíra A; Manjavachi, Marianne N; Segat, Gabriela C; Dias, Fabiana Chaves; Fernandes, Elizabeth S; Calixto, João B

    2017-03-10

    Kinin B1 (B1R) and B2 receptors (B2R) and the transient receptor potential vanilloid 4 (TRPV4) channel are known to play a critical role in the peripheral neuropathy induced by paclitaxel (PTX) in rodents. However, the downstream pathways activated by kinin receptors as well as the sensitizers of the TRPV4 channel involved in this process remain unknown. Herein, we investigated whether kinins sensitize TRPV4 channels in order to maintain PTX-induced peripheral neuropathy in mice. The mechanical hyperalgesia induced by bradykinin (BK, a B2R agonist) or des-Arg(9)-BK (DABK, a B1R agonist) was inhibited by the selective TRPV4 antagonist HC-067047. Additionally, BK was able to sensitize TRPV4, thus contributing to mechanical hyperalgesia. This response was dependent on phospholipase C/protein kinase C (PKC) activation. The selective kinin B1R (des-Arg(9)-[Leu(8)]-bradykinin) and B2R (HOE 140) antagonists reduced the mechanical hyperalgesia induced by PTX, with efficacies and time response profiles similar to those observed for the TRPV4 antagonist (HC-067047). Additionally, both kinin receptor antagonists inhibited the overt nociception induced by hypotonic solution in PTX-injected animals. The same animals presented lower PKCε levels in skin and dorsal root ganglion samples. The selective PKCε inhibitor (εV1-2) reduced the hypotonicity-induced overt nociception in PTX-treated mice with the same magnitude observed for the kinin receptor antagonists. These findings suggest that B1R or B2R agonists sensitize TRPV4 channels to induce mechanical hyperalgesia in mice. This mechanism of interaction may contribute to PTX-induced peripheral neuropathy through the activation of PKCε. We suggest these targets represent new opportunities for the development of effective analgesics to treat chronic pain.

  9. Characterization of Coupled Coil in Seawater for Wireless Power Transfer

    DTIC Science & Technology

    2013-09-01

    9 8. Quality factor of the coils in air, seawater, and atop a ferrite plate...coils (‘blue’). quality factor of the coils in air, seawater, and atop a ferrite plate...was designed to be inserted inside the transmit coil, as shown in Figure 5(b). The receive coil was filled with a ferrite powder to increase its

  10. Variants of the Sir4 Coiled-Coil Domain Improve Binding to Sir3 for Heterochromatin Formation in Saccharomyces cerevisiae.

    PubMed

    Samel, Anke; Rudner, Adam; Ehrenhofer-Murray, Ann E

    2017-04-03

    Heterochromatin formation in the yeast Saccharomyces cerevisiae is characterized by the assembly of the Silent Information Regulator (SIR) complex, which consists of the histone deacetylase Sir2 and the structural components Sir3 and Sir4, and binds to unmodified nucleosomes to provide gene silencing. Sir3 contains an AAA(+) ATPase-like domain, and mutations in an exposed loop on the surface of this domain abrogate Sir3 silencing function in vivo, as well in vitro binding to the Sir2/Sir4 subcomplex. Here, we found that the removal of a single methyl group in the C-terminal coiled-coil domain (mutation T1314S) of Sir4 was sufficient to restore silencing at the silent mating-type loci HMR and HML to a Sir3 version with a mutation in this loop. Restoration of telomeric silencing required further mutations of Sir4 (E1310V and K1325R). Significantly, these mutations in Sir4 restored in vitro complex formation between Sir3 and the Sir4 coiled-coil, indicating that the improved affinity between Sir3 and Sir4 is responsible for the restoration of silencing. Altogether, these observations highlight remarkable properties of selected amino-acid changes at the Sir3-Sir4 interface that modulate the affinity of the two proteins.

  11. Variants of the Sir4 Coiled-Coil Domain Improve Binding to Sir3 for Heterochromatin Formation in Saccharomyces cerevisiae

    PubMed Central

    Samel, Anke; Rudner, Adam; Ehrenhofer-Murray, Ann E.

    2017-01-01

    Heterochromatin formation in the yeast Saccharomyces cerevisiae is characterized by the assembly of the Silent Information Regulator (SIR) complex, which consists of the histone deacetylase Sir2 and the structural components Sir3 and Sir4, and binds to unmodified nucleosomes to provide gene silencing. Sir3 contains an AAA+ ATPase-like domain, and mutations in an exposed loop on the surface of this domain abrogate Sir3 silencing function in vivo, as well in vitro binding to the Sir2/Sir4 subcomplex. Here, we found that the removal of a single methyl group in the C-terminal coiled-coil domain (mutation T1314S) of Sir4 was sufficient to restore silencing at the silent mating-type loci HMR and HML to a Sir3 version with a mutation in this loop. Restoration of telomeric silencing required further mutations of Sir4 (E1310V and K1325R). Significantly, these mutations in Sir4 restored in vitro complex formation between Sir3 and the Sir4 coiled-coil, indicating that the improved affinity between Sir3 and Sir4 is responsible for the restoration of silencing. Altogether, these observations highlight remarkable properties of selected amino-acid changes at the Sir3-Sir4 interface that modulate the affinity of the two proteins. PMID:28188183

  12. Cast Coil Transformer Fire Susceptibility and Reliability Study

    DTIC Science & Technology

    1991-04-01

    developed, including silicone -filled transformers, The epoxy encapsulation of the coils without voids vapor-cooled transformers, RTemp-filled transform...including dry, PCB, 1/2 in., were tested using the procedure in the standard. oil, RTemp, silicone , and other designs. Calibration marks were made 1 in...located on the outside surface of the transformer and nonbuming. All twenty samples extinguished before therefore will be the first item, excluding the

  13. Calcium permeability of transient receptor potential canonical (TRPC) 4 channels measured by TRPC4-GCaMP6s

    PubMed Central

    Ko, Juyeon; Myeong, Jongyun; Yang, Dongki

    2017-01-01

    Conflicting evidence has been obtained regarding whether transient receptor potential cation channels (TRPC) are store-operated channels (SOCs) or receptor-operated channels (ROCs). Moreover, the Ca/Na permeability ratio differs depending on whether the current-voltage (I-V) curve has a doubly rectifying shape or inward rectifying shape. To investigate the calcium permeability of TRPC4 channels, we attached GCaMP6s to TRPC4 and simultaneously measured the current and calcium signals. A TRPC4 specific activator, (–)-englerin A, induced both current and calcium fluorescence with the similar time course. Muscarinic receptor stimulator, carbachol, also induced both current and calcium fluorescence with the similar time course. By forming heteromers with TRPC4, TRPC1 significantly reduced the inward current with outward rectifying I-V curve, which also caused the decrease of calcium fluorescence intensity. These results suggest that GCaMP6s attached to TRPC4 can detect slight calcium changes near TRPC4 channels. Consequently, TRPC4-GCaMP6s can be a useful tool for testing the calcium permeability of TRPC4 channels. PMID:28066150

  14. Micro-fabricated integrated coil and magnetic circuit and method of manufacturing thereof

    DOEpatents

    Mihailovich, Robert E.; Papavasiliou, Alex P.; Mehrotra, Vivek; Stupar, Philip A.; Borwick, III, Robert L.; Ganguli, Rahul; DeNatale, Jeffrey F.

    2017-03-28

    A micro-fabricated electromagnetic device is provided for on-circuit integration. The electromagnetic device includes a core. The core has a plurality of electrically insulating layers positioned alternatingly between a plurality of magnetic layers to collectively form a continuous laminate having alternating magnetic and electrically insulating layers. The electromagnetic device includes a coil embedded in openings of the semiconductor substrate. An insulating material is positioned in the cavity and between the coil and an inner surface of the core. A method of manufacturing the electromagnetic device includes providing a semiconductor substrate having openings formed therein. Windings of a coil are electroplated and embedded in the openings. The insulating material is coated on or around an exposed surface of the coil. Alternating magnetic layers and electrically insulating layers may be micro-fabricated and electroplated as a single and substantially continuous segment on or around the insulating material.

  15. Comparison of a single optimized coil and a Helmholtz pair for magnetic nanoparticle hyperthermia.

    PubMed

    Nieskoski, Michael D; Trembly, B Stuart

    2014-06-01

    Magnetic nanoparticles in a tumor can induce therapeutic heating when energized by an alternating magnetic field from a current-carrying coil outside the body. We analyzed a single-turn, air-core coil carrying a filamentary current to quantify the power absorbed by: a) magnetic nanoparticles at depth in tissue and b) superficial tissue in response to induced eddy currents; we defined this quotient as power ratio (PR). Given some limit on the eddy current heating tolerated by an alert patient, maximizing the PR maximizes the power absorbed in the tumor; all else being equal, this increases the thermal dose delivered to the tumor. The mean eddy current heating rate tolerated in four clinical studies we reviewed equaled 12.5 kW/m (3). We differentiated our analytical expression for PR with respect to the radius of the coil to find the value of radius that maximizes PR. Under reasonable simplifying assumptions, the optimal value of coil radius equaled 1.187 times the depth of the nanoparticle target below the body surface. We also derived the PR of two coils surrounding the body configured as a Helmholtz pair. We computed PR for combinations of nanoparticle depths below the surface and axial locations with respect to the coils. At depths less than 4.6 cm, the optimized single coil had a higher PR than that of the Helmholtz pair and furthermore produced less total ohmic heating within the coil. These results were independent of driving frequency, nanoparticle concentration, tissue electrical conductivity, and magnetic nanoparticle heating rate, provided the latter is assumed to be proportional to the product of frequency and the square of the local magnetic field. This paper supports the clinical application of current-carrying coils to deliver efficacious hyperthermia therapy to tumors injected with magnetic nanoparticles.

  16. A Specialized Multi-Transmit Head Coil for High Resolution fMRI of the Human Visual Cortex at 7T

    PubMed Central

    Sengupta, Shubharthi; Roebroeck, Alard; Kemper, Valentin G.; Poser, Benedikt A.; Zimmermann, Jan; Goebel, Rainer; Adriany, Gregor

    2016-01-01

    Purpose To design, construct and validate radiofrequency (RF) transmit and receive phased array coils for high-resolution visual cortex imaging at 7 Tesla. Methods A 4 channel transmit and 16 channel receive array was constructed on a conformal polycarbonate former. Transmit field efficiency and homogeneity were simulated and validated, along with the Specific Absorption Rate, using B1+ mapping techniques and electromagnetic simulations. Receiver signal-to-noise ratio (SNR), temporal SNR (tSNR) across EPI time series, g-factors for accelerated imaging and noise correlations were evaluated and compared with a commercial 32 channel whole head coil. The performance of the coil was further evaluated with human subjects through functional MRI (fMRI) studies at standard and submillimeter resolutions of upto 0.8mm isotropic. Results The transmit and receive sections were characterized using bench tests and showed good interelement decoupling, preamplifier decoupling and sample loading. SNR for the 16 channel coil was ∼ 1.5 times that of the commercial coil in the human occipital lobe, and showed better g-factor values for accelerated imaging. fMRI tests conducted showed better response to Blood Oxygen Level Dependent (BOLD) activation, at resolutions of 1.2mm and 0.8mm isotropic. Conclusion The 4 channel phased array transmit coil provides homogeneous excitation across the visual cortex, which, in combination with the dual row 16 channel receive array, makes for a valuable research tool for high resolution anatomical and functional imaging of the visual cortex at 7T. PMID:27911950

  17. Innovative applications stimulate coiled tubing development

    SciTech Connect

    Sas-Jaworsky, A. II; Bell, S.

    1996-06-01

    Coiled tubing (CT) is increasingly becoming a viable option to many conventional well operations worldwide. Advanced technology, new equipment and recent field applications have shown CT to be a lower-cost, reliable and effective tool for drilling and recompleting certain wells. Seven example applications from two recent coiled tubing technical conferences are described.

  18. Operator coil monitoring Acceptance Test Procedure

    SciTech Connect

    Erhart, M.F.

    1995-05-16

    The readiness of the Data Acquisition and Control System (DACS) to provide monitoring and control of the Programmable Logic Controller (PLC) abort coils from the Master and RSS stations will be systematically tested during performance of this procedure. It should be noted that these are not physical abort coils but software coils controlled by the software`s ladder logic. The readiness of the DACS to properly interface with the ENRAF wire level gauge installed in the SY-101 storage tank will also be tested. During this test, a verification of all abort coil indications will be conducted at the DACS Development Facility in the 306E Building by injecting an input signal for each DACS sensor that has an associated abort coil until the abort coil actuates, and then ensuring that the status of the abort coil indicated at the Master and RSS stations is correct. Each abort coil will also be tested to ensure that the ``ENABLE`` and ``DISABLE`` controls from the Master and RSS stations function correctly, and only with the use of proper passwords.

  19. Magnetic Fields at the Center of Coils

    ERIC Educational Resources Information Center

    Binder, Philippe; Hui, Kaleonui; Goldman, Jesse

    2014-01-01

    In this note we synthesize and extend expressions for the magnetic field at the center of very short and very long current-carrying coils. Elementary physics textbooks present the following equation for the magnetic field inside a very long current-carrying coil (solenoid): B[subscript sol] = µ[subscript 0] (N/L) I, (1) where I is the current, N…

  20. Helical axis stellarator with noninterlocking planar coils

    DOEpatents

    Reiman, A.; Boozer, A.H.

    1984-03-06

    The present invention generates stellarator fields having favorable properties (magnetic well and large rotational transform) by a simple coil system consisting only of unlinked planar non-circular coils. At large rotational transform toroidal effects on magnetic well and rotational transform are small and can be ignored. We do so herein, specializing in straight helical systems.

  1. Evidence-based pathology: umbilical cord coiling.

    PubMed

    Khong, T Y

    2010-12-01

    The generation of a pathology test result must be based on criteria that are proven to be acceptably reproducible and clinically relevant to be evidence-based. This review de-constructs the umbilical cord coiling index to illustrate how it can stray from being evidence-based. Publications related to umbilical cord coiling were retrieved and analysed with regard to how the umbilical coiling index was calculated, abnormal coiling was defined and reference ranges were constructed. Errors and other influences that can occur with the measurement of the length of the umbilical cord or of the number of coils can compromise the generation of the coiling index. Definitions of abnormal coiling are not consistent in the literature. Reference ranges defining hypocoiling or hypercoiling have not taken those potential errors or the possible effect of gestational age into account. Even the way numerical test results in anatomical pathology are generated, as illustrated by the umbilical coiling index, warrants a critical analysis into its evidence base to ensure that they are reproducible or free from errors.

  2. 49 CFR 236.730 - Coil, receiver.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Coil, receiver. 236.730 Section 236.730 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Coil, receiver. Concentric layers of insulated wire wound around the core of a receiver of an...

  3. Precise Fabrication of Electromagnetic-Levitation Coils

    NASA Technical Reports Server (NTRS)

    Ethridge, E.; Curreri, P.; Theiss, J.; Abbaschian, G.

    1985-01-01

    Winding copper tubing on jig ensures reproducible performance. Sequence of steps insures consistent fabrication of levitation-and-melting coils. New method enables technician to produce eight coils per day, 95 percent of them acceptable. Method employs precise step-by-step procedure on specially designed wrapping and winding jig.

  4. Operator coil monitoring acceptance test procedure

    SciTech Connect

    Erhart, M.F.

    1995-06-05

    The readiness of the Data Acquisition and Control System (DACS) to provide monitoring and control of the Programmable Logic Controller (PLC) abort coils from the Master and RSS stations will be systematically tested during performance of this procedure. It should be noted that these are not physical abort coils but software coils controlled by the software`s ladder logic. The readiness of the DACS to properly interface with the ENRAF wire level gauge installed in the SY101 storage tank will also be tested. During this test, a verification of all abort coil indications will be conducted at the DACS Development Facility in the 306E Building by injecting an input signal for each DACS sensor that has an associated abort coil until the abort coil actuates, and then ensuring that the status of the abort coil indicated at the Master and RSS stations correct. Each abort coil will also be tested to ensure that the ``ENABLE`` and ``DISABLE`` controls from the Master and RSS stations function correctly, and only with the use of proper passwords.

  5. Development of double-layer coupled coil for improving S/N in 7 T small-animal MRI.

    PubMed

    Kim, Kyoung-Nam; Seo, Jeung-Hoon; Han, Sang-Doc; Heo, Phil; Im, Geun Ho; Lee, Jung Hee

    2015-01-01

    The purpose of this study was to develop a new double-layer coupled (DLC) surface radiofrequency (RF) coil using a combination of single-layer planar (SLP) and single-layer circular (SLC) coils, for enhancement of magnetic flux (B1 ) sensitivity and RF penetration in 7 T rat-body magnetic resonance imaging (MRI). The proposed DLC surface coil was fabricated according to an electromagnetic (EM) simulation and validated based on the B1 distribution and bench measurements. The DLC coil performance was quantitatively evaluated based on the signal-to-noise ratio (S/N) and coil-response signal intensity curves in phantom and in vivo rat-body images. In the computational EM calculation and 7 T in vivo experimental results, the DLC surface coil clearly showed an increased S/N and higher RF transmit (B1 (+) ) profiles, compared to those of the SLP and SLC coils. While all surface coils displayed a rapid decrease in the MR signal from the near-coil region to the subject, the results reveal that the DLC coil concept may be used to provide sufficient RF penetration and high S/N and degrees of freedom for use in partial body imaging for 7 T ultra-high-field small-animal MRI.

  6. Various factors affect coiled tubing limits

    SciTech Connect

    Yang, Y.S.

    1996-01-15

    Safety and reliability remain the primary concerns in coiled tubing operations. Factors affecting safety and reliability include corrosion, flexural bending, internal (or external) pressure and tension (or compression), and mechanical damage due to improper use. Such limits as coiled tubing fatigue, collapse, and buckling need to be understood to avoid disaster. With increased use of coiled tubing, operators will gain more experience. But at the same time, with further research and development of coiled tubing, the manufacturing quality will be improved and fatigue, collapse, and buckling models will become more mature, and eventually standard specifications will be available. This paper reviews the uses of coiled tubing and current research on mechanical behavior of said tubing. It also discusses several models used to help predict fatigue and failure levels.

  7. Startup of Large Coil Test Facility

    SciTech Connect

    Haubenreich, P.N.; Bohanan, R.E.; Fietz, W.A.; Luton, J.N.; May, J.R.

    1984-01-01

    The Large Coil Test Facility (LCTF) is being used to test superconducting toroidal field coils about one-third the size of those for INTOR. Eventually, six different coils from four countries will be tested. Operations began in 1983 with acceptance testing of the helium refrigerator/liquefier system. Comprehensive shakedown of the facility and tests with the first three coils (from Japan, the United States, and Switzerland) were successfully accomplished in the summer of 1984. Currents up to 10,200 A and fields up to 6.4 T were reached. Data were obtained on performance of refrigerator, helium distribution, power supplies, controls, and data acquisition systems and on the acoustic emission, voltages, currents, and mechanical strains during charging and discharging the coils.

  8. Rod-Coil Block Polyimide Copolymers

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B. (Inventor); Kinder, James D. (Inventor)

    2005-01-01

    This invention is a series of rod-coil block polyimide copolymers that are easy to fabricate into mechanically resilient films with acceptable ionic or protonic conductivity at a variety of temperatures. The copolymers consist of short-rigid polyimide rod segments alternating with polyether coil segments. The rods and coil segments can be linear, branched or mixtures of linear and branched segments. The highly incompatible rods and coil segments phase separate, providing nanoscale channels for ion conduction. The polyimide segments provide dimensional and mechanical stability and can be functionalized in a number of ways to provide specialized functions for a given application. These rod-coil black polyimide copolymers are particularly useful in the preparation of ion conductive membranes for use in the manufacture of fuel cells and lithium based polymer batteries.

  9. Detection of alpha-helical coiled-coil dimer formation by spin-labeled synthetic peptides: a model parallel coiled-coil peptide and the antiparallel coiled coil formed by a replica of the ProP C-terminus.

    PubMed

    Hillar, Alexander; Tripet, Brian; Zoetewey, David; Wood, Janet M; Hodges, Robert S; Boggs, Joan M

    2003-12-30

    Electron paramagnetic resonance spectroscopy was used to determine relative peptide orientation within homodimeric, alpha-helical coiled-coil structures. Introduction of cysteine (Cys) residues into peptides/proteins for spin labeling allows detection of their oligomerization from exchange broadening or dipolar interactions between residues within 25 A of each other. Two synthetic peptides containing Cys substitutions were used: a 35-residue model peptide and the 30-residue ProP peptide. The model peptide is known to form a stable, parallel homodimeric coiled coil, which is partially destabilized by Cys substitutions at heptad a and d positions (peptides C30a and C33d). The ProP peptide, a 30-residue synthetic peptide, corresponds to residues 468-497 of osmoregulatory transporter ProP from Escherichia coli. It forms a relatively unstable, homodimeric coiled coil that is predicted to be antiparallel in orientation. Cys was introduced in heptad g positions of the ProP peptide, near the N-terminus (K473C, creating peptide C473g) or closer to the center of the sequence (E480C, creating peptide C480g). In contrast to the destabilizing effect of Cys substitution at the core heptad a or d positions of model peptides C30a and C33d, circular dichroism spectroscopy showed that Cys substitutions at the heptad g positions of the ProP peptide had little or no effect on coiled-coil stability. Thermal denaturation analysis showed that spin labeling increased the stability of the coiled coil for all peptides. Strong exchange broadening was detected for both C30a and C33d, in agreement with a parallel structure. EPR spectra of C480g had a large hyperfine splitting of about 90 G, indicative of strong dipole-dipole interactions and a distance between spin-labeled residues of less than 9 A. Spin-spin interactions were much weaker for C473g. These results supported the hypothesis that the ProP peptide primarily formed an antiparallel coiled coil, since formation of a parallel dimer

  10. A study on geometry effect of transmission coil for micro size magnetic induction coil

    NASA Astrophysics Data System (ADS)

    Lee, Kyung Hwa; Jun, Byoung Ok; Kim, Seunguk; Lee, Gwang Jun; Ryu, Mingyu; Choi, Ji-Woong; Jang, Jae Eun

    2016-05-01

    The effects of transmission (Tx) coil structure have been studied for micro-size magnetic induction coil. The size of the receiving (Rx) coil should be shrunk to the micrometer level for the various new applications such as micro-robot and wireless body implanted devices. In case of the macro-scale magnetic induction coil, the power transmission efficiency is generally considered to be higher as the inductance of the transmission coil became larger; however, the large size difference between macro-size Tx coil and micro-size Rx coil can decrease the power transmission efficiency due to the difference of resonance frequency. Here, we study a correlation of the power transmission with the size and distance between the macro-size Tx and micro-size Rx coils using magnetic induction technique. The maximum power efficiency was 0.28/0.23/0.13/0.12% at the distance of 0.3/1/3/5 cm between Rx and Tx coil. In addition, more efficient wireless power transferring method is suggested with a floating coil for the body implantable devices. The voltage output increased up to 5.4 mV than the original one Tx coil system. The results demonstrated the foundational wireless power transferring system with enhanced power efficiency.

  11. Intra-coil interactions in split gradient coils in a hybrid MRI-LINAC system

    NASA Astrophysics Data System (ADS)

    Tang, Fangfang; Freschi, Fabio; Sanchez Lopez, Hector; Repetto, Maurizio; Liu, Feng; Crozier, Stuart

    2016-04-01

    An MRI-LINAC system combines a magnetic resonance imaging (MRI) system with a medical linear accelerator (LINAC) to provide image-guided radiotherapy for targeting tumors in real-time. In an MRI-LINAC system, a set of split gradient coils is employed to produce orthogonal gradient fields for spatial signal encoding. Owing to this unconventional gradient configuration, eddy currents induced by switching gradient coils on and off may be of particular concern. It is expected that strong intra-coil interactions in the set will be present due to the constrained return paths, leading to potential degradation of the gradient field linearity and image distortion. In this study, a series of gradient coils with different track widths have been designed and analyzed to investigate the electromagnetic interactions between coils in a split gradient set. A driving current, with frequencies from 100 Hz to 10 kHz, was applied to study the inductive coupling effects with respect to conductor geometry and operating frequency. It was found that the eddy currents induced in the un-energized coils (hereby-referred to as passive coils) positively correlated with track width and frequency. The magnetic field induced by the eddy currents in the passive coils with wide tracks was several times larger than that induced by eddy currents in the cold shield of cryostat. The power loss in the passive coils increased with the track width. Therefore, intra-coil interactions should be included in the coil design and analysis process.

  12. Mosquito coil emissions and health implications.

    PubMed

    Liu, Weili; Zhang, Junfeng; Hashim, Jamal H; Jalaludin, Juliana; Hashim, Zailina; Goldstein, Bernard D

    2003-09-01

    Burning mosquito coils indoors generates smoke that can control mosquitoes effectively. This practice is currently used in numerous households in Asia, Africa, and South America. However, the smoke may contain pollutants of health concern. We conducted the present study to characterize the emissions from four common brands of mosquito coils from China and two common brands from Malaysia. We used mass balance equations to determine emission rates of fine particles (particulate matter < 2.5 microm in diameter; PM(2.5)), polycyclic aromatic hydrocarbons (PAHs), aldehydes, and ketones. Having applied these measured emission rates to predict indoor concentrations under realistic room conditions, we found that pollutant concentrations resulting from burning mosquito coils could substantially exceed health-based air quality standards or guidelines. Under the same combustion conditions, the tested Malaysian mosquito coils generated more measured pollutants than did the tested Chinese mosquito coils. We also identified a large suite of volatile organic compounds, including carcinogens and suspected carcinogens, in the coil smoke. In a set of experiments conducted in a room, we examined the size distribution of particulate matter contained in the coil smoke and found that the particles were ultrafine and fine. The findings from the present study suggest that exposure to the smoke of mosquito coils similar to the tested ones can pose significant acute and chronic health risks. For example, burning one mosquito coil would release the same amount of PM(2.5) mass as burning 75-137 cigarettes. The emission of formaldehyde from burning one coil can be as high as that released from burning 51 cigarettes.

  13. Mosquito coil emissions and health implications.

    PubMed Central

    Liu, Weili; Zhang, Junfeng; Hashim, Jamal H; Jalaludin, Juliana; Hashim, Zailina; Goldstein, Bernard D

    2003-01-01

    Burning mosquito coils indoors generates smoke that can control mosquitoes effectively. This practice is currently used in numerous households in Asia, Africa, and South America. However, the smoke may contain pollutants of health concern. We conducted the present study to characterize the emissions from four common brands of mosquito coils from China and two common brands from Malaysia. We used mass balance equations to determine emission rates of fine particles (particulate matter < 2.5 microm in diameter; PM(2.5)), polycyclic aromatic hydrocarbons (PAHs), aldehydes, and ketones. Having applied these measured emission rates to predict indoor concentrations under realistic room conditions, we found that pollutant concentrations resulting from burning mosquito coils could substantially exceed health-based air quality standards or guidelines. Under the same combustion conditions, the tested Malaysian mosquito coils generated more measured pollutants than did the tested Chinese mosquito coils. We also identified a large suite of volatile organic compounds, including carcinogens and suspected carcinogens, in the coil smoke. In a set of experiments conducted in a room, we examined the size distribution of particulate matter contained in the coil smoke and found that the particles were ultrafine and fine. The findings from the present study suggest that exposure to the smoke of mosquito coils similar to the tested ones can pose significant acute and chronic health risks. For example, burning one mosquito coil would release the same amount of PM(2.5) mass as burning 75-137 cigarettes. The emission of formaldehyde from burning one coil can be as high as that released from burning 51 cigarettes. PMID:12948883

  14. A Built for Purpose Micro-Hole Coiled Tubing Rig (MCTR)

    SciTech Connect

    Bart Patton

    2007-09-30

    This report will serve as the final report on the work performed from the contract period October 2005 thru April 2007. The project 'A Built for Purpose Microhole Coiled Tubing Rig (MCTR)' purpose was to upgrade an existing state-of-the-art Coiled Tubing Drilling Rig to a Microhole Coiled Tubing Rig (MCTR) capable of meeting the specifications and tasks of the Department of Energy. The individual tasks outlined to meet the Department of Energy's specifications are: (1) Concept and development of lubricator and tool deployment system; (2) Concept and development of process control and data acquisition; (3) Concept and development of safety and efficiency improvements; and (4) Final unit integration and testing. The end result of the MCTR upgrade has produced a unit capable of meeting the following requirements: (1) Capable of handling 1-inch through 2-3/8-inch coiled tubing (Currently dressed for 2-3/8-inch coiled tubing and capable of running up to 3-1/2-inch coiled tubing); (2) Capable of drilling and casing surface, intermediate, production and liner hole intervals; (3) Capable of drilling with coiled tubing and has all controls and installation piping for a top drive; (4) Rig is capable of running 7-5/8-inch range 2 casing; and (5) Capable of drilling 5,000 ft true vertical depth (TVD) and 6,000 ft true measured depth (TMD).

  15. An alternative conformation of the gp41 heptad repeat 1 region coiled coil exists in the human immunodeficiency virus (HIV-1) envelope glycoprotein precursor

    SciTech Connect

    Mische, Claudia C.; Yuan Wen; Strack, Bettina; Craig, Stewart; Farzan, Michael; Sodroski, Joseph . E-mail: joseph_sodroski@dfci.harvard.edu

    2005-07-20

    The human immunodeficiency virus (HIV-1) transmembrane envelope glycoprotein, gp41, which mediates virus-cell fusion, exists in at least three different conformations within the trimeric envelope glycoprotein complex. The structures of the prefusogenic and intermediate states are unknown; structures representing the postfusion state have been solved. In the postfusion conformation, three helical heptad repeat 2 (HR2) regions pack in an antiparallel fashion into the hydrophobic grooves on the surface of a triple-helical coiled coil formed by the heptad repeat 1 (HR1) regions. We studied the prefusogenic conformation of gp41 by mutagenic alteration of membrane-anchored and soluble forms of the HIV-1 envelope glycoproteins. Our results indicate that, in the HIV-1 envelope glycoprotein precursor, the gp41 HR1 region is in a conformation distinct from that of a trimeric coiled coil. Thus, the central gp41 coiled coil is formed during the transition of the HIV-1 envelope glycoproteins from the precursor state to the receptor-bound intermediate.

  16. Central domain of DivIB caps the C-terminal regions of the FtsL/DivIC coiled-coil rod.

    PubMed

    Masson, Soizic; Kern, Thomas; Le Gouëllec, Audrey; Giustini, Cécile; Simorre, Jean-Pierre; Callow, Philip; Vernet, Thierry; Gabel, Frank; Zapun, André

    2009-10-02

    DivIB(FtsQ), FtsL, and DivIC(FtsB) are enigmatic membrane proteins that are central to the process of bacterial cell division. DivIB(FtsQ) is dispensable in specific conditions in some species, and appears to be absent in other bacterial species. The presence of FtsL and DivIC(FtsB) appears to be conserved despite very low sequence conservation. The three proteins form a complex at the division site, FtsL and DivIC(FtsB) being associated through their extracellular coiled-coil region. We report here structural investigations by NMR, small-angle neutron and x-ray scattering, and interaction studies by surface plasmon resonance, of the complex of DivIB, FtsL, and DivIC from Streptococcus pneumoniae, using soluble truncated forms of the proteins. We found that one side of the "bean"-shaped central beta-domain of DivIB interacts with the C-terminal regions of the dimer of FtsL and DivIC. This finding is corroborated by sequence comparisons across bacterial genomes. Indeed, DivIB is absent from species with shorter FtsL and DivIC proteins that have an extracellular domain consisting only of the coiled-coil segment without C-terminal conserved regions (Campylobacterales). We propose that the main role of the interaction of DivIB with FtsL and DivIC is to help the formation, or to stabilize, the coiled-coil of the latter proteins. The coiled-coil of FtsL and DivIC, itself or with transmembrane regions, could be free to interact with other partners.

  17. Dynamic contrast-enhanced susceptibility-weighted perfusion MRI (DSC-MRI) in a glioma model of the rat brain using a conventional receive-only surface coil with a inner diameter of 47 mm at a clinical 1.5 T scanner.

    PubMed

    Ulmer, Stephan; Reeh, Matthias; Krause, Joerg; Herdegen, Thomas; Heldt-Feindt, Janka; Jansen, Olav; Rohr, Axel

    2008-07-30

    Magnetic resonance (MR) imaging in animal models is usually performed in expensive dedicated small bore animal scanners of limited availability. In the present study a standard clinical 1.5 T MR scanner was used for morphometric and dynamic contrast-enhanced susceptibility-weighted MR imaging (DSC-MRI) of a glioma model of the rat brain. Ten male Wistar rats were examined with coronal T2-weighted, and T1-weighted images (matrix 128 x 128, FOV 64 mm) after implantation of an intracerebral tumor xenografts (C6) using a conventional surface coil. For DSC-MRI a T2*-weighted sequence (TR/TE=30/14 ms, matrix 64 x 64, FOV 90 mm; slice thickness of 1.5mm) was performed. Regions of interest were defined within the tumor and the non-affected contralateral hemisphere and the mean transit time (MTT) was determined. Tumor dimensions in MR predicted well its real size as proven by histology. The MTT of contrast agent passing through the brain was significantly decelerated in the tumor compared to the unaffected hemisphere (p<0.001, paired t-test), which is most likely due to the leakage of contrast agent through the disrupted blood brain barrier. This setup offers advanced MR imaging of small animals without the need for dedicated animal scanners or dedicated custom-made coils.

  18. Inverting the Biot-Savart integral in the context of stellarator coil determination

    NASA Astrophysics Data System (ADS)

    Schmitt, Ronald Frederick

    The design of power-efficient stellarator coils that are practical to engineer and allow access to the plasma is a difficult task that involves mathematical and physics issues in addition to the engineering concerns. The complexity of stellarator coils is a major factor in the cost and viability of stellarator fusion reactors. Coil determination is a complex inverse problem with many subtleties. The problem of coil determination is tantamount to inverting the Biot-Savart integral of magnetostatics. The inverse of the Biot-Savart operator tends to be ill-conditioned, dramatically emphasizing high-order Fourier modes. Using a simplistic method to invert this integral results in coils of impracticable shape and current magnitude. Two methods are introduced to optimize stellarator coil determination. The first technique involves the application of linear perturbation theory to the coil design problem. First, the flux modes that cause the N0 largest perturbations are determined, where N0 is an adjustable parameter that in practice is much smaller than the total number of Fourier modes. The next step is to project the coil equations into the smaller mathematical space of these dominant modes. This technique reduces the constraints on the coils such that the set of equations only includes those flux modes that are needed to approximate the shape of the plasma surface. This technique aims to produce smoother coils by avoiding the over-constrained nature of other methods. The second technique involves rank-ordering and Gram-Schmidt orthogonalization of the Fourier modes, Gmn (theta p, ϕp), of the Biot-Savart integral between two surfaces. The rank-ordering of the modes in terms of magnitude, |Gmn|, gives a natural way to decompose the current in terms of the most influential modes. The solution for the coil current is then constrained to only use the most influential modes. The two methods are applied to the extant Helically Symmetric Experiment (HSX) stellarator and

  19. N@a and N@d: Oligomer and Partner Specification by Asparagine in Coiled-Coil Interfaces.

    PubMed

    Fletcher, Jordan M; Bartlett, Gail J; Boyle, Aimee L; Danon, Jonathan J; Rush, Laura E; Lupas, Andrei N; Woolfson, Derek N

    2017-02-17

    The α-helical coiled coil is one of the best-studied protein-protein interaction motifs. As a result, sequence-to-structure relationships are available for the prediction of natural coiled-coil sequences and the de novo design of new ones. However, coiled coils adopt a wide range of oligomeric states and topologies, and our understanding of the specification of these and the discrimination between them remains incomplete. Gaps in our knowledge assume more importance as coiled coils are used increasingly to construct biomimetic systems of higher complexity; for this, coiled-coil components need to be robust, orthogonal, and transferable between contexts. Here, we explore how the polar side chain asparagine (Asn, N) is tolerated within otherwise hydrophobic helix-helix interfaces of coiled coils. The long-held view is that Asn placed at certain sites of the coiled-coil sequence repeat selects one oligomer state over others, which is rationalized by the ability of the side chain to make hydrogen bonds, or interactions with chelated ions within the coiled-coil interior of the favored state. We test this with experiments on de novo peptide sequences traditionally considered as directing parallel dimers and trimers, and more widely through bioinformatics analysis of natural coiled-coil sequences and structures. We find that when located centrally, rather than near the termini of such coiled-coil sequences, Asn does exert the anticipated oligomer-specifying influence. However, outside of these bounds, Asn is observed less frequently in the natural sequences, and the synthetic peptides are hyperthermostable and lose oligomer-state specificity. These findings highlight that not all regions of coiled-coil repeat sequences are equivalent, and that care is needed when designing coiled-coil interfaces.

  20. Optimized parallel transmit and receive radiofrequency coil for ultrahigh-field MRI of monkeys.

    PubMed

    Gilbert, Kyle M; Gati, Joseph S; Barker, Kevin; Everling, Stefan; Menon, Ravi S

    2016-01-15

    Monkeys are a valuable model for investigating the structure and function of the brain. To attain the requisite resolution to resolve fine anatomical detail and map localized brain activation requires radiofrequency (RF) coils that produce high signal-to-noise ratios (SNRs) both spatially (image SNR) and temporally. Increasing the strength of the static magnetic field is an effective method to improve SNR, yet this comes with commensurate challenges in RF coil design. First, at ultrahigh field strengths, the magnetic field produced by a surface coil in a dielectric medium is asymmetric. In neuroimaging of rhesus macaques, this complex field pattern is compounded by the heterogeneous structure of the head. The confluence of these effects results in a non-uniform flip angle, but more markedly, a suboptimal circularly polarized mode with reduced transmit efficiency. Secondly, susceptibility-induced geometric distortions are exacerbated when performing echo-planar imaging (EPI), which is a standard technique in functional studies. This requires receive coils capable of parallel imaging with low noise amplification during image reconstruction. To address these challenges at 7T, this study presents a parallel (8-channel) transmit coil developed for monkey imaging, along with a highly parallel (24-channel) receive coil. RF shimming with the parallel-transmit coil produced significant advantages-the transmit field was 38% more uniform than a traditional circularly polarized mode and 54% more power-efficient, demonstrating that parallel-transmit coils should be used for monkey imaging at ultrahigh field strengths. The receive coil had the ability to accelerate along an arbitrary axis with at least a three-fold reduction factor, thereby reducing geometric distortions in whole-brain EPI.

  1. Spaced-based search coil magnetometers

    NASA Astrophysics Data System (ADS)

    Hospodarsky, George B.

    2016-12-01

    Search coil magnetometers are one of the primary tools used to study the magnetic component of low-frequency electromagnetic waves in space. Their relatively small size, mass, and power consumption, coupled with a good frequency range and sensitivity, make them ideal for spaceflight applications. The basic design of a search coil magnetometer consists of many thousands of turns of wire wound on a high permeability core. When a time-varying magnetic field passes through the coil, a time-varying voltage is induced due to Faraday's law of magnetic induction. The output of the coil is usually attached to a preamplifier, which amplifies the induced voltage and conditions the signal for transmission to the main electronics (usually a low-frequency radio receiver). Search coil magnetometers are usually used in conjunction with electric field antenna to measure electromagnetic plasma waves in the frequency range of a few hertz to a few tens of kilohertzs. Search coil magnetometers are used to determine the properties of waves, such as comparing the relative electric and magnetic field amplitudes of the waves, or to investigate wave propagation parameters, such as Poynting flux and wave normal vectors. On a spinning spacecraft, they are also sometimes used to determine the background magnetic field. This paper presents some of the basic design criteria of search coil magnetometers and discusses design characteristics of sensors flown on a number of spacecraft.

  2. Correcting coils in end magnets of accelerators

    NASA Astrophysics Data System (ADS)

    Kassab, L. R.; Gouffon, P.

    1998-05-01

    We present an empirical investigation of the correcting coils behavior used to homogenize the field distribution of the race-track microtron accelerator end magnets. These end magnets belong to the second stage of the 30.0 MeV cw electron accelerator under construction at IFUSP, the race-track microtron booster, in which the beam energy is raised from 1.97 to 5.1 MeV. The correcting coils are attached to the pole faces and are based on the inhomogeneities of the magnetic field measured. The performance of these coils, when operating the end magnets with currents that differ by +/-10% from the one used in the mappings that originated the coils copper leads, is presented. For one of the magnets, adjusting conveniently the current of the correcting coils makes it possible to homogenize field distributions of different intensities, once their shapes are practically identical to those that originated the coils. For the other one, the shapes are changed and the coils are less efficient. This is related to intrinsic factors that determine the inhomogeneities. However, we obtained uniformity of 0.001% in both cases.

  3. Routine phasing of coiled-coil protein crystal structures with AMPLE

    PubMed Central

    Thomas, Jens M. H.; Keegan, Ronan M.; Bibby, Jaclyn; Winn, Martyn D.; Mayans, Olga; Rigden, Daniel J.

    2015-01-01

    Coiled-coil protein folds are among the most abundant in nature. These folds consist of long wound α-helices and are architecturally simple, but paradoxically their crystallographic structures are notoriously difficult to solve with molecular-replacement techniques. The program AMPLE can solve crystal structures by molecular replacement using ab initio search models in the absence of an existent homologous protein structure. AMPLE has been benchmarked on a large and diverse test set of coiled-coil crystal structures and has been found to solve 80% of all cases. Successes included structures with chain lengths of up to 253 residues and resolutions down to 2.9 Å, considerably extending the limits on size and resolution that are typically tractable by ab initio methodologies. The structures of two macromolecular complexes, one including DNA, were also successfully solved using their coiled-coil components. It is demonstrated that both the ab initio modelling and the use of ensemble search models contribute to the success of AMPLE by comparison with phasing attempts using single structures or ideal polyalanine helices. These successes suggest that molecular replacement with AMPLE should be the method of choice for the crystallo­graphic elucidation of a coiled-coil structure. Furthermore, AMPLE may be able to exploit the presence of a coiled coil in a complex to provide a convenient route for phasing. PMID:25866657

  4. Phase reconstruction from multiple coil data using a virtual reference coil

    PubMed Central

    Parker, Dennis L.; Payne, Allison; Todd, Nick; Hadley, J. Rock

    2013-01-01

    Purpose This paper develops a method to obtain optimal estimates of absolute magnetization phase from multiple-coil MRI data. Methods The element-specific phases of a multi-element receiver coil array are accounted for by using the phase of a real or virtual reference coil that is sensitive over the entire imaged volume. The virtual-reference coil is generated as a weighted combination of measurements from all receiver coils. The phase-corrected multiple coil complex images are combined using the inverse covariance matrix. These methods are tested on images of an agar phantom, an in vivo breast, and an anesthetized rabbit obtained using combinations of four, nine, and three receiver channels, respectively. Results The four- and three- channel acquisitions require formation of a virtual-reference receiver coil while one channel of the nine-channel receive array has a sensitivity profile covering the entire imaged volume. Referencing to a real or virtual coil gives receiver phases that are essentially identical except for the individual receiver channel noise. The resulting combined images, which account for receiver channel noise covariance, show the expected reduction in phase variance. Conclusions The proposed virtual reference coil method determines a phase distribution for each coil from which an optimal phase map can be obtained. PMID:24006172

  5. Crystal Structure of the Central Coiled-Coil Domain from Human Liprin-[beta]2

    SciTech Connect

    Stafford, Ryan L.; Tang, Ming-Yun; Sawaya, Michael R.; Phillips, Martin L.; Bowie, James U.

    2012-02-07

    Liprins are a conserved family of scaffolding proteins important for the proper regulation and development of neuronal synapses. Humans have four liprin-{alpha}s and two liprin-{beta}s which all contain long coiled-coil domains followed by three tandem SAM domains. Complex interactions between the coiled-coil and SAM domains are thought to create liprin scaffolds, but the structural and biochemical properties of these domains remain largely uncharacterized. In this study we find that the human liprin-{beta}2 coiled-coil forms an extended dimer. Several protease-resistant subdomains within the liprin-{beta}1 and liprin-{beta}2 coiled-coils were also identified. A 2.0 {angstrom} crystal structure of the central, protease-resistant core of the liprin-{beta}2 coiled-coil reveals a parallel helix orientation. These studies represent an initial step toward determining the overall architecture of liprin scaffolds and understanding the molecular basis for their synaptic functions.

  6. A Set of Computationally Designed Orthogonal Antiparallel Homodimers that Expands the Synthetic Coiled-Coil Toolkit

    PubMed Central

    2015-01-01

    Molecular engineering of protein assemblies, including the fabrication of nanostructures and synthetic signaling pathways, relies on the availability of modular parts that can be combined to give different structures and functions. Currently, a limited number of well-characterized protein interaction components are available. Coiled-coil interaction modules have been demonstrated to be useful for biomolecular design, and many parallel homodimers and heterodimers are available in the coiled-coil toolkit. In this work, we sought to design a set of orthogonal antiparallel homodimeric coiled coils using a computational approach. There are very few antiparallel homodimers described in the literature, and none have been measured for cross-reactivity. We tested the ability of the distance-dependent statistical potential DFIRE to predict orientation preferences for coiled-coil dimers of known structure. The DFIRE model was then combined with the CLASSY multistate protein design framework to engineer sets of three orthogonal antiparallel homodimeric coiled coils. Experimental measurements confirmed the successful design of three peptides that preferentially formed antiparallel homodimers that, furthermore, did not interact with one additional previously reported antiparallel homodimer. Two designed peptides that formed higher-order structures suggest how future design protocols could be improved. The successful designs represent a significant expansion of the existing protein-interaction toolbox for molecular engineers. PMID:25337788

  7. Inhibition of the 26S proteasome by peptide mimics of the coiled-coil region of its ATPase subunits.

    PubMed

    Inobe, Tomonao; Genmei, Reiko

    Regulation of proteasomal degradation is an indispensable tool for biomedical studies. Thus, there is demand for novel proteasome inhibitors. Proteasomal degradation requires formation of coiled-coil structure by the N-terminal region of ATPase subunits of the proteasome cap. Here we show that peptides that mimic the N-terminal coiled-coil region of ATPase subunits interfere with proteasome function. These results suggest that coiled-coil peptides represent promising new proteasome inhibitors and that N-terminal coiled-coil regions of ATPase subunits are targets for proteasome inhibition.

  8. Rugged telemetry system for coiled-tubing earth drilling

    NASA Astrophysics Data System (ADS)

    Weis, R. Stephen; Beadle, Brad M.

    1997-09-01

    The development of a rugged optical fiber telemetry system for coiled-tubing earth-drilling is described. The transmitter and receiver of the telemetry system are located on the surface. A high temperature fiber cable connects a serial array of downhole modulators with the surface. Each modulator consists of an intrinsic fiber Bragg grating (FBG) fixed to a piezoelectric transducer (PZ). Each modulating signal causes a PZ to stretch its attached FBG, shifting the wavelength of the light reflected by the grating. The wavelength shift of the grating-reflected light is detected at the output using a Mach-Zehnder interferometer.

  9. Kv4 Channels Underlie the Subthreshold-Operating A-type K-current in Nociceptive Dorsal Root Ganglion Neurons.

    PubMed

    Phuket, Thanawath Ratanadilok Na; Covarrubias, Manuel

    2009-01-01

    The dorsal root ganglion (DRG) contains heterogeneous populations of sensory neurons including primary nociceptive neurons and C-fibers implicated in pain signaling. Recent studies have demonstrated DRG hyperexcitability associated with downregulation of A-type K(+) channels; however, the molecular correlate of the corresponding A-type K(+) current (I(A)) has remained hypothetical. Kv4 channels may underlie the I(A) in DRG neurons. We combined electrophysiology, molecular biology (Whole-Tissue and Single-Cell RT-PCR) and immunohistochemistry to investigate the molecular basis of the I(A) in acutely dissociated DRG neurons from 7- to 8-day-old rats. Whole-cell recordings demonstrate a robust tetraethylammonium-resistant (20 mM) and 4-aminopyridine-sensitive (5 mM) I(A). Matching Kv4 channel properties, activation and inactivation of this I(A) occur in the subthreshold range of membrane potentials and the rate of recovery from inactivation is rapid and voltage-dependent. Among Kv4 transcripts, the DRG expresses significant levels of Kv4.1 and Kv4.3 mRNAs. Also, single small-medium diameter DRG neurons ( approximately 30 mum) exhibit correlated frequent expression of mRNAs encoding Kv4.1 and Nav1.8, a known nociceptor marker. In contrast, the expressions of Kv1.4 and Kv4.2 mRNAs at the whole-tissue and single-cell levels are relatively low and infrequent. Kv4 protein expression in nociceptive DRG neurons was confirmed by immunohistochemistry, which demonstrates colocalization of Kv4.3 and Nav1.8, and negligible expression of Kv4.2. Furthermore, specific dominant-negative suppression and overexpression strategies confirmed the contribution of Kv4 channels to I(A) in DRG neurons. Contrasting the expression patterns of Kv4 channels in the central and peripheral nervous systems, we discuss possible functional roles of these channels in primary sensory neurons.

  10. Corrosion degradation mechanisms in coiled tubing

    SciTech Connect

    Kane, R.D.; Cayard, M.S.

    1994-12-31

    This paper reviews the historical aspects related to the development of coiled tubing for oilfield drilling, logging, workover and production operations. It focuses on the metallurgical and process variables of coiled tubing and their interrelationship with aspects of the downhole service environment and the resultant corrosion performance. Special emphasis is placed on (1) operating conditions that can lead to excessive corrosion and/or cracking damage and corrosion fatigue and (2) metallurgical and processing parameters which can be controlled to maximize coiled tubing resistance to corrosion degradation.

  11. Coiled tubing 1994: Enhanced value through innovation

    SciTech Connect

    Teel, M.E.

    1994-01-01

    This paper discusses the growth in use of coiled tubing in well completion and development processes. Larger tubing is now available and operations expand into more demanding and critical areas as a result of research and development, innovation, and better understanding of materials and tube development. This article highlights significant coiled tubing operations, services, practices, and applications since 1990. It describes the types of materials used in coiled tubing and the strength associated with each type. Various case studies are described which use this tubing in both horizontal and directional drilling. It also is discussed as it relates to various types of enhanced recovery techniques for oil and gas wells.

  12. Collapse tests expand coiled tubing uses

    SciTech Connect

    Walker, E.J.; Mason, C.M. )

    1990-03-05

    Tests on coiled tubing have allowed the authors' company to decrease well work costs for some operations, especially squeeze cementing. They conducted collapse tests of 1.5 in. (0.095 in. and 0.109-in. wall thickness) and 1.75-in. (0.109-in. wall thickness) OD coiled tubing while under imposed axial load and differential pressure. These tests were performed to define accurate field operating limits for this size of coiled tubing. Findings from these tests are reported and discussed.

  13. Promoted-Combustion Chamber with Induction Heating Coil

    NASA Technical Reports Server (NTRS)

    Richardson, Erin; Hagood, Richard; Lowery, Freida; Herald, Stephen

    2006-01-01

    An improved promoted-combustion system has been developed for studying the effects of elevated temperatures on the flammability of metals in pure oxygen. In prior promoted-combustion chambers, initial temperatures of metal specimens in experiments have been limited to the temperatures of gas supplies, usually near room temperature. Although limited elevated temperature promoted-combustion chambers have been developed using water-cooled induction coils for preheating specimens, these designs have been limited to low-pressure operation due to the hollow induction coil. In contrast, the improved promoted-combustion chamber can sustain a pressure up to 10 kpsi (69 MPa) and, through utilization of a solid induction coil, is capable of preheating a metal specimen up to its melting point [potentially in excess of 2,000 F (approximately equal to 1,100 C)]. Hence, the improved promoted combustion chamber makes a greater range of physical conditions and material properties accessible for experimentation. The chamber consists of a vertical cylindrical housing with an inner diameter of 8 in. (20.32 cm) and an inner height of 20.4 in. (51.81 cm). A threaded, sealing cover at one end of the housing can be unscrewed to gain access for installing a specimen. Inlet and outlet ports for gases are provided. Six openings arranged in a helical pattern in the chamber wall contain sealed sapphire windows for viewing an experiment in progress. The base of the chamber contains pressure-sealed electrical connectors for supplying power to the induction coil. The connectors feature a unique design that prevents induction heating of the housing and the pressure sealing surfaces; this is important because if such spurious induction heating were allowed to occur, chamber pressure could be lost. The induction coil is 10 in. (25.4 cm) long and is fitted with a specimen holder at its upper end. At its lower end, the induction coil is mounted on a ceramic base, which affords thermal insulation to

  14. Helical coil thermal hydraulic model

    NASA Astrophysics Data System (ADS)

    Caramello, M.; Bertani, C.; De Salve, M.; Panella, B.

    2014-11-01

    A model has been developed in Matlab environment for the thermal hydraulic analysis of helical coil and shell steam generators. The model considers the internal flow inside one helix and its associated control volume of water on the external side, both characterized by their inlet thermodynamic conditions and the characteristic geometry data. The model evaluates the behaviour of the thermal-hydraulic parameters of the two fluids, such as temperature, pressure, heat transfer coefficients, flow quality, void fraction and heat flux. The evaluation of the heat transfer coefficients as well as the pressure drops has been performed by means of the most validated literature correlations. The model has been applied to one of the steam generators of the IRIS modular reactor and a comparison has been performed with the RELAP5/Mod.3.3 code applied to an inclined straight pipe that has the same length and the same elevation change between inlet and outlet of the real helix. The predictions of the developed model and RELAP5/Mod.3.3 code are in fairly good agreement before the dryout region, while the dryout front inside the helical pipes is predicted at a lower distance from inlet by the model.

  15. Microhole Coiled Tubing Bottom Hole Assemblies

    SciTech Connect

    Don Macune

    2008-06-30

    The original objective of the project, to deliver an integrated 3 1/8-inch diameter Measurement While Drilling (MWD) and Logging While Drilling (LWD) system for drilling small boreholes using coiled tubing drilling, has been achieved. Two prototype systems have been assembled and tested in the lab. One of the systems has been successfully tested downhole in a conventional rotary drilling environment. Development of the 3 1/8-inch system has also lead to development and commercialization of a slightly larger 3.5-inch diameter system. We are presently filling customer orders for the 3.5-inch system while continuing with commercialization of the 3 1/8-inch system. The equipment developed by this project will be offered for sale to multiple service providers around the world, enabling the more rapid expansion of both coiled tubing drilling and conventional small diameter drilling. The project was based on the reuse of existing technology whenever possible in order to minimize development costs, time, and risks. The project was begun initially by Ultima Labs, at the time a small company ({approx}12 employees) which had successfully developed a number of products for larger oil well service companies. In September, 2006, approximately 20 months after inception of the project, Ultima Labs was acquired by Sondex plc, a worldwide manufacturer of downhole instrumentation for cased hole and drilling applications. The acquisition provided access to proven technology for mud pulse telemetry, downhole directional and natural gamma ray measurements, and surface data acquisition and processing, as well as a global sales and support network. The acquisition accelerated commercialization through existing Sondex customers. Customer demand resulted in changes to the product specification to support hotter (150 C) and deeper drilling (20,000 psi pressure) than originally proposed. The Sondex acquisition resulted in some project delays as the resistivity collar was interfaced to a

  16. Magnetic propulsion of a magnetic device using three square-Helmholtz coils and a square-Maxwell coil.

    PubMed

    Ha, Yong H; Han, Byung H; Lee, Soo Y

    2010-02-01

    We introduce a square coil system for remote magnetic navigation of a magnetic device without any physical movements of the coils. We used three square-Helmholtz coils and a square-Maxwell coil for magnetic propulsion of a small magnet along the desired path. All the square coils are mountable on a cubic frame that has an opening to accommodate a living subject. The square-Helmholtz coils control the magnetic propulsion direction by generating uniform magnetic field along the desired direction while the square-Maxwell coil controls the propulsion force by generating magnetic gradient field. We performed magnetic propulsion experiments with a down-scaled coil set and a three-channel coil driver. Experimental results demonstrate that we can use the square coil set for magnetic navigation of a magnetic device without any physical movements of the coils.

  17. Discrete control of TRPV4 channel function in the distal nephron by protein kinases A and C.

    PubMed

    Mamenko, Mykola; Zaika, Oleg L; Boukelmoune, Nabila; Berrout, Jonathan; O'Neil, Roger G; Pochynyuk, Oleh

    2013-07-12

    We have recently documented that the Ca(2+)-permeable TRPV4 channel, which is abundantly expressed in distal nephron cells, mediates cellular Ca(2+) responses to elevated luminal flow. In this study, we combined Fura-2-based [Ca(2+)]i imaging with immunofluorescence microscopy in isolated split-opened distal nephrons of C57BL/6 mice to probe the molecular determinants of TRPV4 activity and subcellular distribution. We found that activation of the PKC pathway with phorbol 12-myristate 13-acetate significantly increased [Ca(2+)]i responses to flow without affecting the subcellular distribution of TRPV4. Inhibition of PKC with bisindolylmaleimide I diminished cellular responses to elevated flow. In contrast, activation of the PKA pathway with forskolin did not affect TRPV4-mediated [Ca(2+)]i responses to flow but markedly shifted the subcellular distribution of the channel toward the apical membrane. These actions were blocked with the specific PKA inhibitor H-89. Concomitant activation of the PKA and PKC cascades additively enhanced the amplitude of flow-induced [Ca(2+)]i responses and greatly increased basal [Ca(2+)]i levels, indicating constitutive TRPV4 activation. This effect was precluded by the selective TRPV4 antagonist HC-067047. Therefore, the functional status of the TRPV4 channel in the distal nephron is regulated by two distinct signaling pathways. Although the PKA-dependent cascade promotes TRPV4 trafficking and translocation to the apical membrane, the PKC-dependent pathway increases the activity of the channel on the plasma membrane.

  18. Synaptotagmin I delays the fast inactivation of Kv1.4 channel through interaction with its N-terminus

    PubMed Central

    2014-01-01

    Background The voltage-gated potassium channel Kv1.4 is an important A-type potassium channel and modulates the excitability of neurons in central nervous system. Analysis of the interaction between Kv1.4 and its interacting proteins is helpful to elucidate the function and mechanism of the channel. Results In the present research, synaptotagmin I was for the first time demonstrated to be an interacting protein of Kv1.4 and its interaction with Kv1.4 channel did not require the mediation of other synaptic proteins. Using patch-clamp technique, synaptotagmin I was found to delay the inactivation of Kv1.4 in HEK293T cells in a Ca2+-dependent manner, and this interaction was proven to have specificity. Mutagenesis experiments indicated that synaptotagmin I interacted with the N-terminus of Kv1.4 and thus delayed its N-type fast inactivation. Conclusion These data suggest that synaptotagmin I is an interacting protein of Kv1.4 channel and, as a negative modulator, may play an important role in regulating neuronal excitability and synaptic efficacy. PMID:24423395

  19. Low intravascular pressure activates endothelial cell TRPV4 channels, local Ca2+ events, and IKCa channels, reducing arteriolar tone

    PubMed Central

    Bagher, Pooneh; Beleznai, Timea; Kansui, Yasuo; Mitchell, Ray; Garland, Christopher J.; Dora, Kim A.

    2012-01-01

    Endothelial cell (EC) Ca2+-activated K channels (SKCa and IKCa channels) generate hyperpolarization that passes to the adjacent smooth muscle cells causing vasodilation. IKCa channels focused within EC projections toward the smooth muscle cells are activated by spontaneous Ca2+ events (Ca2+ puffs/pulsars). We now show that transient receptor potential, vanilloid 4 channels (TRPV4 channels) also cluster within this microdomain and are selectively activated at low intravascular pressure. In arterioles pressurized to 80 mmHg, ECs generated low-frequency (∼2 min−1) inositol 1,4,5-trisphosphate receptor-based Ca2+ events. Decreasing intraluminal pressure below 50 mmHg increased the frequency of EC Ca2+ events twofold to threefold, an effect blocked with the TRPV4 antagonist RN1734. These discrete events represent both TRPV4-sparklet- and nonsparklet-evoked Ca2+ increases, which on occasion led to intracellular Ca2+ waves. The concurrent vasodilation associated with increases in Ca2+ event frequency was inhibited, and basal myogenic tone was increased, by either RN1734 or TRAM-34 (IKCa channel blocker), but not by apamin (SKCa channel blocker). These data show that intraluminal pressure influences an endothelial microdomain inversely to alter Ca2+ event frequency; at low pressures the consequence is activation of EC IKCa channels and vasodilation, reducing the myogenic tone that underpins tissue blood-flow autoregulation. PMID:23071308

  20. Screen-printed flexible MRI receive coils.

    PubMed

    Corea, Joseph R; Flynn, Anita M; Lechêne, Balthazar; Scott, Greig; Reed, Galen D; Shin, Peter J; Lustig, Michael; Arias, Ana C

    2016-03-10

    Magnetic resonance imaging is an inherently signal-to-noise-starved technique that limits the spatial resolution, diagnostic image quality and results in typically long acquisition times that are prone to motion artefacts. This limitation is exacerbated when receive coils have poor fit due to lack of flexibility or need for padding for patient comfort. Here, we report a new approach that uses printing for fabricating receive coils. Our approach enables highly flexible, extremely lightweight conforming devices. We show that these devices exhibit similar to higher signal-to-noise ratio than conventional ones, in clinical scenarios when coils could be displaced more than 18 mm away from the body. In addition, we provide detailed material properties and components performance analysis. Prototype arrays are incorporated within infant blankets for in vivo studies. This work presents the first fully functional, printed coils for 1.5- and 3-T clinical scanners.

  1. Evolution of coiled tubing drilling technology accelerates

    SciTech Connect

    Simmons, J.; Adam, B.

    1993-09-01

    This paper reviews the status of coiled tubing technology in oil and gas drilling operations. The paper starts with a description of current coiled tubing technology and provides a cost comparison between conventional and coiled tubing drilling. The results show that offshore operations are already competitive while onshore operations will still lag behind conventional drilling methods. A list of known coiled tubing drilling operations is provided which gives the current borehole diameters and depths associated with this technology. The paper then goes on to provide the advantages and disadvantages of the technology. The advantages include improved well control, a continuous drillstring, reduced mobilization costs, simplified logging and measurement-while drilling measurements, and less tripping required. The disadvantages include high friction with the borehole wall, downhole motors required, limited drillhole size, and fatigued or damaged sections of the tubing cannot be removed. Finally, a review of the reliability of this technology is provided.

  2. The Magnetic Field of Helmholtz Coils

    ERIC Educational Resources Information Center

    Berridge, H. J. J.

    1975-01-01

    Describes the magnetic field of Helmholtz coils qualitatively and then provides the basis for a quantitative expression. Since the mathematical calculations are very involved, a computer program for solving the mathematical expression is presented and explained. (GS)

  3. Electrical wire insulation and electromagnetic coil

    DOEpatents

    Bich, George J.; Gupta, Tapan K.

    1984-01-01

    An electromagnetic coil for high temperature and high radiation application in which glass is used to insulate the electrical wire. A process for applying the insulation to the wire is disclosed which results in improved insulation properties.

  4. Coiled tubing cuts horizontal screen repair cost

    SciTech Connect

    Crow, W.; Hill, P.; Johnston, R.

    1996-01-01

    This article presents a case history of the successful workover performed by a coiled tubing unit (CTU) on Mississippi Canyon (MC) Block 109 Well A-24 in the US Gulf of Mexico to clean out sand and install new concentric screen for sand control. Workover design and operational details discussed are: Workover design -- hole-cleaning hydraulics, CT and screen predictions and comparison considerations; Workover operations -- cleanout, running packer and screens, coiled tubing (CT) weights, acid treatment and nitrogen lift and flow back.

  5. Heterogeneous Superconducting Low-Noise Sensing Coils

    NASA Technical Reports Server (NTRS)

    Hahn, Inseob; Penanen, Konstantin I.; Ho Eom, Byeong

    2008-01-01

    A heterogeneous material construction has been devised for sensing coils of superconducting quantum interference device (SQUID) magnetometers that are subject to a combination of requirements peculiar to some advanced applications, notably including low-field magnetic resonance imaging for medical diagnosis. The requirements in question are the following: The sensing coils must be large enough (in some cases having dimensions of as much as tens of centimeters) to afford adequate sensitivity; The sensing coils must be made electrically superconductive to eliminate Johnson noise (thermally induced noise proportional to electrical resistance); and Although the sensing coils must be cooled to below their superconducting- transition temperatures with sufficient cooling power to overcome moderate ambient radiative heat leakage, they must not be immersed in cryogenic liquid baths. For a given superconducting sensing coil, this combination of requirements can be satisfied by providing a sufficiently thermally conductive link between the coil and a cold source. However, the superconducting coil material is not suitable as such a link because electrically superconductive materials are typically poor thermal conductors. The heterogeneous material construction makes it possible to solve both the electrical- and thermal-conductivity problems. The basic idea is to construct the coil as a skeleton made of a highly thermally conductive material (typically, annealed copper), then coat the skeleton with an electrically superconductive alloy (typically, a lead-tin solder) [see figure]. In operation, the copper skeleton provides the required thermally conductive connection to the cold source, while the electrically superconductive coating material shields against Johnson noise that originates in the copper skeleton.

  6. Passive energy dump for superconducting coil protection

    DOEpatents

    Luton, J.N. Jr.

    1973-01-16

    The patent describes a passive resistance type energy dump for the protection of the coils of a superconducting magnet. Insertion heaters are immersed in a rigid container filled with a fusible alloy. The energy dump is connected across the coils of the superconducting magnet wherein individual heater elements are connected singly to the windings or otherwise according to the energy dumping requirements upon transition of the magnet to a normal state.

  7. Coil tests and superconductor code calculations for the stellarator W7-X coils

    NASA Astrophysics Data System (ADS)

    Baldzuhn, J.; Ehmler, H.; Hoelting, A.; Hertel, K.; Sborchia, C.; Genini, L.; Schild, T.

    2006-07-01

    For the stellarator Wendelstein 7-X, a plasma fusion experiment, the performance of the superconducting coils is tested in a cryogenic test facility. Focus is on the quench behaviour of these coils. Some key data of the coils are given here. The coil quench data, obtained during the tests, are compared to GANDALF code calculations. GANDALF is a one-dimensional finite elements code for the simulation of the quench properties of superconducting CICC cables. Good consistency between measurement and calculation is found for the development of the resistive voltage and temperature increase during the quench.

  8. pH sensitive coiled coils: a strategy for enhanced liposomal drug delivery

    NASA Astrophysics Data System (ADS)

    Reja, Rahi M.; Khan, Mohsina; Singh, Sumeet K.; Misra, Rajkumar; Shiras, Anjali; Gopi, Hosahudya N.

    2016-02-01

    Stimuli responsive controlled release from liposome based vesicles is a promising strategy for the site specific delivery of drugs. Herein, we report the design of pH sensitive coiled coils and their incorporation into the liposome as triggers for the controlled release of encapsulated drugs. The designed coiled coil peptides with the incorporation of environment sensitive fluorescent amino acids were found to be stable at physiological pH and unstructured while changing the pH of the environment to either acidic or basic. This pH dependent conformational switch of the coiled-coil polypeptides was exploited as triggers for the enhanced release of the encapsulated drug molecules from liposomes. The SEM, DLS and TEM analysis revealed the uniform morphology of the peptide liposome hybrid vesicles. Further, the drug encapsulated liposome internalization experiments with cancer cells revealed the enhanced release and accumulation of drugs in the acidic lysosomal compartments in comparison with liposomes without coiled coils.Stimuli responsive controlled release from liposome based vesicles is a promising strategy for the site specific delivery of drugs. Herein, we report the design of pH sensitive coiled coils and their incorporation into the liposome as triggers for the controlled release of encapsulated drugs. The designed coiled coil peptides with the incorporation of environment sensitive fluorescent amino acids were found to be stable at physiological pH and unstructured while changing the pH of the environment to either acidic or basic. This pH dependent conformational switch of the coiled-coil polypeptides was exploited as triggers for the enhanced release of the encapsulated drug molecules from liposomes. The SEM, DLS and TEM analysis revealed the uniform morphology of the peptide liposome hybrid vesicles. Further, the drug encapsulated liposome internalization experiments with cancer cells revealed the enhanced release and accumulation of drugs in the acidic

  9. AC loss measurements in HTS coil assemblies with hybrid coil structures

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenan; Long, Nicholas J.; Staines, Mike; Badcock, Rodney A.; Bumby, Chris W.; Buckley, Robert G.; Amemiya, Naoyuki

    2016-09-01

    Both AC loss and wire cost in coil windings are critical factors for high temperature superconductor (HTS) AC machinery applications. We present AC loss measurement results in three HTS coil assemblies at 77 K and 65 K which have a hybrid coil structure comprising one central winding (CW) and two end windings (EWs) wound with ReBCO and BSCCO wires with different self-field I c values at 77 K. All AC loss results in the coil assemblies are hysteretic and the normalized AC losses in the coil assemblies at different temperatures can be scaled with the I c value of the coil assemblies. The normalised results show that AC loss in a coil assembly with BSCCO CW can be reduced by using EWs wound with high I c ReBCO wires, whilst further AC loss reduction can be achieved by replacing the BSCCO CW with ReBCO CW. The results imply that a flexible hybrid coil structure is possible which considers both AC loss and wire cost in coil assemblies.

  10. The Rad50 coiled-coil domain is indispensable for Mre11 complex functions.

    PubMed

    Hohl, Marcel; Kwon, Youngho; Galván, Sandra Muñoz; Xue, Xiaoyu; Tous, Cristina; Aguilera, Andrés; Sung, Patrick; Petrini, John H J

    2011-09-04

    The Mre11 complex (Mre11, Rad50 and Xrs2 in Saccharomyces cerevisiae) influences diverse functions in the DNA damage response. The complex comprises the globular DNA-binding domain and the Rad50 hook domain, which are linked by a long and extended Rad50 coiled-coil domain. In this study, we constructed rad50 alleles encoding truncations of the coiled-coil domain to determine which Mre11 complex functions required the full length of the coils. These mutations abolished telomere maintenance and meiotic double-strand break (DSB) formation, and severely impaired homologous recombination, indicating a requirement for long-range action. Nonhomologous end joining, which is probably mediated by the globular domain of the Mre11 complex, was also severely impaired by alteration of the coiled-coil and hook domains, providing the first evidence of their influence on this process. These data show that functions of Mre11 complex are integrated by the coiled coils of Rad50.

  11. Development of an inductively-coupled MR coil system for imaging and spectroscopic analysis of an implantable bioartificial construct at 11.1T

    PubMed Central

    Volland, Nelly A.; Mareci, Thomas H.; Constantinidis, Ioannis; Simpson, Nicholas E.

    2010-01-01

    Developing a method to non-invasively monitor tissue engineered constructs is critical for the optimization of construct design and for assessing therapeutic efficacy. For this purpose, NMR is a powerful technique that can be used to obtain both images and spectroscopic data. But the inherent sensitivity of NMR limits the observation of a bioartificial construct with current NMR surface coil technology. In this study, we address this limitation through the development of an inductively-coupled, implantable coil system, demonstrate its use at high field (11.1T), and investigate the use of this coil system for monitoring a bioartificial construct in vitro and in vivo. The results establish that large gains in signal-to-noise can be obtained with this coil system over that obtainable with a surface coil. This coil system provides a means to quantitatively analyze the structure and function of implanted bioartificial organs. PMID:20373400

  12. Preliminary Process Design of ITER ELM Coil Bracket Brazing

    NASA Astrophysics Data System (ADS)

    LI, Xiangbin; SHI, Yi

    2015-03-01

    With the technical requirement of the International Thermonuclear Experimental Reactor (ITER) project, the manufacture and assembly technology of the mid Edge Localized Modes (ELM) coil was developed by the Institute of Plasma Physics, Chinese Academy of Science (ASIPP). As the gap between the bracket and the Stainless Steel jacketed and Mineral Insulated Conductor (SSMIC) can be larger than 0.5 mm instead of 0.01 mm to 0.1 mm as in normal industrial cases, the process of mid ELM coil bracket brazing to the SSMICT becomes quiet challenging, from a technical viewpoint. This paper described the preliminary design of ELM coil bracket brazing to the SSMIC process, the optimal bracket brazing curve and the thermal simulation of the bracket furnace brazing method developed by ANSYS. BAg-6 foil (Bag50Cu34Zn16) plus BAg-1a paste (Bag45CuZnCd) solders were chosen as the brazing filler. By testing an SSMICT prototype, it is shown that the average gap between the bracket and the SSMIC could be controlled to 0.2-0.3 mm, and that there were few voids in the brazing surface. The results also verified that the preliminary design had a favorable heat conducting performance in the bracket.

  13. Improved Plasma Properties in RT-1 with a Levitated Coil

    NASA Astrophysics Data System (ADS)

    Saitoh, Haruhiko; Yoshida, Zensho; Ogawa, Yuichi; Morikawa, Junji; Watanabe, Sho; Yano, Yoshihisa; Suzuki, Junko

    2007-11-01

    Ring Trap-1 (RT-1) is a novel device to confine plasmas in a magnetosphere-like configuration generated by a superconducting internal conductor. The ring coil is excited with a permanent current of Ic=250kAT that is magnetically levitated in the chamber to minimize disturbances to the plasmas. The main scientific objective of RT-1 is to realize self-organized states of flowing plasmas with a very high beta value, where the thermal pressure of plasmas is balanced by the hydrodynamic pressure of a fast flow (S. M. Mahajan & Z. Yoshida, PRL 81, 4863 (1998), Z. Yoshida & S. M. Mahajan, PRL 88, 095001 (2002)). We have started a series of initial plasma experiments since 2006, and in this study, we focused on the improvements of plasma properties by the coil levitation. Hydrogen plasmas were generated by an 8.2GHz ECH system. When the coil was levitated, a line integrated electron density increased to ne=4x10^17m-2 and the peak density was close to the O-mode cut off density of the microwave. The beta value of the plasma was ˜3% and the pressure was mainly sustained by a high energy component of electrons. The magnetic surface configuration of RT-1 is also suitable for the confinement of non-neutral plasmas. Experiments on electron plasmas were conducted in RT-1 expanding the previous work in a normal conducting device.

  14. Auxiliary coil controls temperature of RF induction heater

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Auxiliary coil controls the temperature of an RF induction furnace that is powered by a relatively unstable RF generator. Manual or servoed adjustments of the relative position of the auxiliary coil, which is placed in close proximity to the RF coil, changes the looseness of the RF coil and hence the corresponding heating effect of its RF field.

  15. The effect of fluid flow on coiled tubing reach

    SciTech Connect

    Bhalla, K.; Walton, I.C.

    1996-12-31

    A critical parameter to the success of many coiled tubing (CT) operations in highly deviated or horizontal wells is the depth penetration that can be attained before the CT buckles and locks up. Achieving a desired depth is always critical in CT operations and attaining an additional reach of a few hundred feet can be crucial. This paper addresses the effect of fluid flow in the CT and in the CT/wellbore annulus on the state of force and stress in the CT, and thereby predicts its effect on the reach attainable by the CT. The flow of fluid through the CT and annulus between the CT and borehole modifies the pressures and the effective force which governs the mechanical stability of the CT. The net force per unit length due to fluid flow in the coiled tubing and annulus between the coiled tubing casing/well is calculated in terms of the shear stress and its effect on the onset of buckling and lockup is determined. The model is then implemented in a full tubing forces calculation and the effect of flowing fluids and producing fluids on reach is analyzed. The new model is utilized in the design of commercial jobs. The exact analytic model shows that fluid flow inside the CT has zero impact on reach, that downward flow in the annulus has a favourable impact, and upward flow in the annulus reduces the maximum attainable reach. Using the full tubing forces model, a coiled tubing job can be designed taking into account the flow of a fluid with a specified rheology, density and flow rate. Thus the feasibility of attaining a given reach can be more accurately determined. Results are presented in the form of the surface weight for commercial wells and compared to field jobs.

  16. New printed circuit boards magnetic coils in the vacuum vessel of J-TEXT tokamak for position measurement.

    PubMed

    Qiu, S S; Zhuang, G; Zhang, M; Xia, D H; Rao, B; Zhang, X Q; Pan, Y; Gentle, K

    2010-10-01

    Four sets of magnetic diagnostic coils, which are printed on machinable ceramic printed circuit boards (PCB), are designed, fabricated, installed, and tested in the Joint Texas Experimental Tokamak (J-TEXT) vacuum vessel for detecting the plasma radial and vertical displacements relative to the geometric center of the vacuum vessel in Ohmic discharges. Each coordinate is determined by a pair of variable cross-section Rogowski and saddle coils, which measure the tangential and normal magnetic fields (relative to the coil surface). These coils are suitable for mass production and offer advantages in vacuum compatibility and temperature tolerance that are important for J-TEXT. Position measurements using PCB coils are compared with those from soft x-ray image system and match the position well.

  17. New printed circuit boards magnetic coils in the vacuum vessel of J-TEXT tokamak for position measurement

    SciTech Connect

    Qiu, S. S.; Zhuang, G.; Zhang, M.; Xia, D. H.; Rao, B.; Zhang, X. Q.; Pan, Y.; Gentle, K.

    2010-10-15

    Four sets of magnetic diagnostic coils, which are printed on machinable ceramic printed circuit boards (PCB), are designed, fabricated, installed, and tested in the Joint Texas Experimental Tokamak (J-TEXT) vacuum vessel for detecting the plasma radial and vertical displacements relative to the geometric center of the vacuum vessel in Ohmic discharges. Each coordinate is determined by a pair of variable cross-section Rogowski and saddle coils, which measure the tangential and normal magnetic fields (relative to the coil surface). These coils are suitable for mass production and offer advantages in vacuum compatibility and temperature tolerance that are important for J-TEXT. Position measurements using PCB coils are compared with those from soft x-ray image system and match the position well.

  18. Radiation-hard electrical coil and method for its fabrication

    DOEpatents

    Grieggs, R.J.; Blake, R.D.; Gac, F.D.

    1982-06-29

    A radiation-hard insulated electrical coil and method for making the same are disclosed. In accordance with the method, a conductor, preferably copper, is wrapped with an aluminum strip and then tightly wound into a coil. The aluminum-wrapped coil is then annealed to relax the conductor in the coiled configuration. The annealed coil is then immersed in an alkaline solution to dissolve the aluminum strip, leaving the bare conductor in a coiled configuration with all of the windings closely packed yet uniformly spaced from one another. The coil is then insulated with a refractory insulating material. In the preferred embodiment, the coil is insulated by coating it with a vitreous enamel and subsequently potting the enamelled coil in a castable ceramic concrete. The resulting coil is substantially insensitive to radiation and may be operated continuously in high radiation environments for long periods of time.

  19. Atomic hydrodynamics of DNA: coil-uncoil-coil transitions in a wall-bounded shear flow.

    PubMed

    Sandberg, William C; Wang, Guan M

    2008-12-01

    Extensive experimental work on the response of DNA molecules to externally applied forces and on the dynamics of DNA molecules flowing in microchannels and nanochannels has been carried out over the past two decades, however, there has not been available, until now, any atomic-scale means of analyzing nonequilibrium DNA response dynamics. There has not therefore been any way to investigate how the backbone and side-chain atoms along the length of a DNA molecule interact with the molecules and ions of the flowing solvent and with the atoms of passing boundary surfaces. We report here on the application of the nonequilibrium biomolecular dynamics simulation method that we developed [G. M. Wang and W. C. Sandberg, Nanotechnology 18, 4819 (2007)] to analyze, at the atomic interaction force level, the conformational dynamics of short-chain single-stranded DNA molecules in a shear flow near a surface. This is a direct atomic computational analysis of the hydrodynamic interaction between a biomolecule and a flowing solvent. The DNA molecules are observed to exhibit conformational behaviors including coils, hairpin loops, and figure-eight shapes that have neither been previously measured experimentally nor observed computationally, as far as we know. We relate the conformational dynamics to the atomic interaction forces experienced throughout the length of a molecule as it moves in the flowing solvent past the surface boundary. We show that the DNA conformational dynamics is related to the asymmetry in the molecular environment induced by the motion of the surrounding molecules and the atoms of the passing surface. We also show that while the asymmetry in the environment is necessary, it is not sufficient to produce the observed conformational dynamics. A time variation in the asymmetry, due in our case to a shear flow, must also exist. In order to contrast these results with the usual experimental situation of purely diffusive motion in thermal equilibrium we have also

  20. Mesenchymal stem cells and endothelial progenitor cells accelerate intra-aneurysmal tissue organization after treatment with SDF-1α-coated coils.

    PubMed

    Gao, Yuyuan; Lu, Ziming; Chen, Chengwei; Cui, Xubo; Liu, Yaqi; Zheng, Tao; Jiang, Xiaodan; Zeng, Chi; Quan, Daping; Wang, Qiujing

    2016-04-01

    Recurrences of aneurysms remain the major drawback of detachable coils for the endovascular treatment of intracranial aneurysms. The aim of the present study is to develop new modified coils, coating the surface of platinum coils with silk fibroin (SF) consisting of stromal cell-derived factor-1α (SDF-1α), and evaluate its acceleration of organization of cavities and reduction of lumen size in a rat aneurysm model. The morphological characteristics of SDF-1α-coated coils were examined using scanning electron microscopy (SEM). Fifty experimental aneurysms were created and randomly divided into five groups: three groups were embolized with SDF-1α-coated coils (8 mm) and two of these groups need transplantation of mesenchymal stem cells (MSCs) or endothelial progenitor cells (EPCs); one group was embolized with bare coils (8 mm) and another group severed as control. After coil implantation for 14 or 28 days, the coils were harvested and histological analysis was performed. SEM photographs showed that SF/SDF-1α-coated coils have uniform size and a thin film compared with bare coils. In the group treated with SDF-1α-coated coils, tissue organization was accelerated and the proliferation of α-smooth muscle actin positive cells was promoted in the aneurysmal sac. Compared with unmodified coils, on day 28, tissue organization was significantly greater in the group treated with SDF-1α-coated coils and MSC or EPC transplantation. These results suggest that SDF-1α-coated coils with MSC or EPC transplantation may be beneficial in the aneurysm healing and endothelialization at the orifice of embolized aneurysm.

  1. Remodelling inactivation gating of Kv4 channels by KChIP1, a small-molecular-weight calcium-binding protein

    PubMed Central

    Beck, Edward J; Bowlby, Mark; An, W Frank; Rhodes, Kenneth J; Covarrubias, Manuel

    2002-01-01

    Calcium-binding proteins dubbed KChIPs favour surface expression and modulate inactivation gating of neuronal and cardiac A-type Kv4 channels. To investigate their mechanism of action, Kv4.1 or Kv4.3 were expressed in Xenopus laevis oocytes, either alone or together with KChIP1, and the K+ currents were recorded using the whole-oocyte voltage-clamp and patch-clamp methods. KChIP1 similarly remodels gating of both channels. At positive voltages, KChIP1 slows the early phase of the development of macroscopic inactivation. By contrast, the late phase is accelerated, which allows complete inactivation in < 500 ms. Thus, superimposed traces from control and KChIP1-remodelled currents crossover. KChIP1 also accelerates closed-state inactivation and recovery from inactivation (3- to 5-fold change). The latter effect is dominating and, consequently, the prepulse inactivation curves exhibit depolarizing shifts (ΔV = 4–12 mV). More favourable closed-state inactivation may also contribute to the overall faster inactivation at positive voltages because Kv4 channels significantly inactivate from the preopen closed state. KChIP1 favours this pathway further by accelerating channel closing. The peak G-V curves are modestly leftward shifted in the presence of KChIP1, but the apparent ‘threshold’ voltage of current activation remains unaltered. Single Kv4.1 channels exhibited multiple conductance levels that ranged between 1.8 and 5.6 pS in the absence of KChIP1 and between 1.9 and 5.3 pS in its presence. Thus, changes in unitary conductance do not contribute to current upregulation by KChIP1. An allosteric kinetic model explains the kinetic changes by assuming that KChIP1 mainly impairs open-state inactivation, favours channel closing and lowers the energy barrier of closed-state inactivation. PMID:11826158

  2. Versatile Fill Coils: Initial Experience as Framing Coils for Oblong Aneurysms

    PubMed Central

    Osanai, Toshiya; Bain, Mark; Hui, Ferdinand K

    2014-01-01

    Summary Coil embolization of oblong aneurysms is difficult because the majority of commercially available coils are manufactured with a helical or spherical tertiary structure. While adopting framing strategies for oblong aneurysms (aspect ratio ≥ 2: 1), traditional coils may be undersized in the long axis but oversized in the short axis, resulting in increased aneurysmal wall stress, risk of re-rupture, and difficulty creating a basket that respects the aneurysmal neck. We review three cases in which versatile filling coils (VFCs) were used as the initial coils for embolization of oblong aneurysms and report coil distribution characteristics and clinical outcomes. Packing density after VFC implantation was assessed using the software AngioSuite-Neuro edition and AngioCalc. Illustrative case: a 58-year-old woman experienced a subarachnoid hemorrhage from a ruptured anterior communicating artery aneurysm (7.5 mm × 3.5 mm). A 3-6 mm × 15 cm VFC was selected as the first coil because the flexibility of its wave−loop structure facilitates framing of an irregularly shaped aneurysm. The loop portions of the structures tend to be pressed to the extremes of the aneurysmal sac by the wave component. The VFC was introduced smoothly into the aneurysmal sac without catheter kickback. We were then able to insert detachable filling coils without any adjunctive technique and achieved complete occlusion. Complete occlusion without severe complications was achieved in all three cases in our study. Average packing density after the first coil was 15.63%. VFC coils may have a specific role in framing oblong aneurysms given their complex loop-wave design, allowing spacing of the coils at the dome and neck while keeping sac stress to a minimum. PMID:24976090

  3. Surgical management of an ACM aneurysm eight years after coiling.

    PubMed

    Pogády, P; Fellner, F; Trenkler, J; Wurm, G

    2007-04-01

    The authors present a case report on rebleeding of a medial cerebral aneurysm (MCA) eight years after complete endovascular coiling. The primarily successfully coiled MCA aneurysm showed a local regrowth which, however, was not the source of the rebleeding. The angiogram demonstrated no evidence of contrast filling of the coiled segment, but according to intraoperative findings (haematoma location, displacement of coils, evident place of rupture) there is no doubt that the coiled segment of the aneurysm was responsible for the haemorrhage.

  4. Structural Correlation of the Neck Coil with the Coiled-coil (CC1)-Forkhead-associated (FHA) Tandem for Active Kinesin-3 KIF13A.

    PubMed

    Ren, Jinqi; Huo, Lin; Wang, Wenjuan; Zhang, Yong; Li, Wei; Lou, Jizhong; Xu, Tao; Feng, Wei

    2016-02-12

    Processive kinesin motors often contain a coiled-coil neck that controls the directionality and processivity. However, the neck coil (NC) of kinesin-3 is too short to form a stable coiled-coil dimer. Here, we found that the coiled-coil (CC1)-forkhead-associated (FHA) tandem (that is connected to NC by Pro-390) of kinesin-3 KIF13A assembles as an extended dimer. With the removal of Pro-390, the NC-CC1 tandem of KIF13A unexpectedly forms a continuous coiled-coil dimer that can be well aligned into the CC1-FHA dimer. The reverse introduction of Pro-390 breaks the NC-CC1 coiled-coil dimer but provides the intrinsic flexibility to couple NC with the CC1-FHA tandem. Mutations of either NC, CC1, or the FHA domain all significantly impaired the motor activity. Thus, the three elements within the NC-CC1-FHA tandem of KIF13A are structurally interrelated to form a stable dimer for activating the motor. This work also provides the first direct structural evidence to support the formation of a coiled-coil neck by the short characteristic neck domain of kinesin-3.

  5. Structural Correlation of the Neck Coil with the Coiled-coil (CC1)-Forkhead-associated (FHA) Tandem for Active Kinesin-3 KIF13A*

    PubMed Central

    Ren, Jinqi; Huo, Lin; Wang, Wenjuan; Zhang, Yong; Li, Wei; Lou, Jizhong; Xu, Tao; Feng, Wei

    2016-01-01

    Processive kinesin motors often contain a coiled-coil neck that controls the directionality and processivity. However, the neck coil (NC) of kinesin-3 is too short to form a stable coiled-coil dimer. Here, we found that the coiled-coil (CC1)-forkhead-associated (FHA) tandem (that is connected to NC by Pro-390) of kinesin-3 KIF13A assembles as an extended dimer. With the removal of Pro-390, the NC-CC1 tandem of KIF13A unexpectedly forms a continuous coiled-coil dimer that can be well aligned into the CC1-FHA dimer. The reverse introduction of Pro-390 breaks the NC-CC1 coiled-coil dimer but provides the intrinsic flexibility to couple NC with the CC1-FHA tandem. Mutations of either NC, CC1, or the FHA domain all significantly impaired the motor activity. Thus, the three elements within the NC-CC1-FHA tandem of KIF13A are structurally interrelated to form a stable dimer for activating the motor. This work also provides the first direct structural evidence to support the formation of a coiled-coil neck by the short characteristic neck domain of kinesin-3. PMID:26680000

  6. Shallow gas well drilling with coiled tubing in the San Juan Basin

    SciTech Connect

    Moon, R.G.; Ovitz, R.W.; Guild, G.J.; Biggs, M.D.

    1996-12-31

    Coiled tubing is being utilized to drill new wells, for re-entry drilling to deepen or laterally extend existing wells, and for underbalanced drilling to prevent formation damage. Less than a decade old, coiled tubing drilling technology is still in its inaugral development stage. Initially, utilizing coiled tubing was viewed as a {open_quotes}science project{close_quotes} to determine the validity of performing drilling operations in-lieu of the conventional rotary rig. Like any new technology, the initial attempts were not always successful, but did show promise as an economical alternative if continued efforts were made in the refinement of equipment and operational procedures. A multiwell project has been completed in the San Juan Basin of Northwestern New Mexico which provides documentation indicating that coiled tubing can be an alternative to the conventional rotary rig. A 3-well pilot project, a 6-well project was completed uniquely utilizing the combined resources of a coiled tubing service company, a producing company, and a drilling contractor. This combination of resources aided in the refinement of surface equipment, personnel, mud systems, jointed pipe handling, and mobilization. The results of the project indicate that utilization of coiled tubing for the specific wells drilled was an economical alternative to the conventional rotary rig for drilling shallow gas wells.

  7. Magnetostatic simulation on a novel design of axially multi-coiled magnetorheological brakes

    NASA Astrophysics Data System (ADS)

    Ubaidillah, Permata, A. N. S.; Wibowo, A.; Budiana, E. P.; Yahya, I.; Mazlan, S. A.

    2016-03-01

    This paper describes the 3D magnetostatic simulation of a novel design axially multi-coiled magnetorheological (MRB). The proposed model is expected to produce a concentrated magnetic flux on the surface of the rotor disk brake. Thus, the braking torque enhancement is expected to be higher than that of conventional big size single-coil-equipped disk-type MRB. The axially multi-coiled MRB design features multiple electromagnetic poles from by several coils placed in the axial direction outside the MRB body. The magnetostatic analysis was developed utilizing finite element software namely ANSOFT-MAXWELL in 3D environment. The distribution of magnetic flux was investigated in a pair of the coil that represents the other pairs of electromagnetic parts. The simulation was done in 0.5 mm gap filled by magnetorheological fluids (MRFs) (MRF-132DG). The simulation was performed in various applied currents i.e. 0.25, 0.5, 0.75, 1, 1.5, and 2 Amperes. The results showed that the axially multi-coiled MRB provides a considerable magnetic flux (maximum of 337 mT/area). The active energizing areas of the MRB are proven to be more intensive than the conventional MRB. The proposed MRB exhibited a compact and robust design for achieving high torque MRB.

  8. Heat transfer characteristics of a new helically coiled crimped spiral finned tube heat exchanger

    NASA Astrophysics Data System (ADS)

    Srisawad, Kwanchanok; Wongwises, Somchai

    2009-02-01

    In the present study, the heat transfer characteristics in dry surface conditions of a new type of heat exchanger, namely a helically coiled finned tube heat exchanger, is experimentally investigated. The test section, which is a helically coiled fined tube heat exchanger, consists of a shell and a helical coil unit. The helical coil unit consists of four concentric helically coiled tubes of different diameters. Each tube is constructed by bending straight copper tube into a helical coil. Aluminium crimped spiral fins with thickness of 0.5 mm and outer diameter of 28.25 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Ambient air is used as a working fluid in the shell side while hot water is used for the tube-side. The test runs are done at air mass flow rates ranging between 0.04 and 0.13 kg/s. The water mass flow rates are between 0.2 and 0.4 kg/s. The water temperatures are between 40 and 50°C. The effects of the inlet conditions of both working fluids flowing through the heat exchanger on the heat transfer coefficients are discussed. The air-side heat transfer coefficient presented in term of the Colburn J factor is proportional to inlet-water temperature and water mass flow rate. The heat exchanger effectiveness tends to increase with increasing water mass flow rate and also slightly increases with increasing inlet water temperature.

  9. A Wide Linear Range Eddy Current Displacement Sensor Equipped with Dual-Coil Probe Applied in the Magnetic Suspension Flywheel

    PubMed Central

    Fang, Jiancheng; Wen, Tong

    2012-01-01

    The Eddy Current Displacement Sensor (ECDS) is widely used in the Magnetic Suspension Flywheel (MSFW) to measure the tiny clearance between the rotor and the magnetic bearings. The linear range of the ECDS is determined by the diameter of its probe coil. Wide clearances must be measured in some new MSFWs recently designed for the different space missions, but the coil diameter is limited by some restrictions. In this paper, a multi-channel ECDS equipped with dual-coil probes is proposed to extend the linear range to satisfy the demands of such MSFWs. In order to determine the best configuration of the dual-coil probe, the quality factors of the potential types of the dual-coil probes, the induced eddy current and the magnetic intensity on the surface of the measuring object are compared with those of the conventional single-coil probe. The linear range of the ECDS equipped with the selected dual-coil probe is extended from 1.1 mm to 2.4 mm under the restrictions without adding any cost for additional compensation circuits or expensive coil materials. The effectiveness of the linear range extension ability and the dynamic response of the designed ECDS are confirmed by the testing and the applications in the MSFW. PMID:23112623

  10. A wide linear range Eddy Current Displacement Sensor equipped with dual-coil probe applied in the Magnetic Suspension Flywheel.

    PubMed

    Fang, Jiancheng; Wen, Tong

    2012-01-01

    The Eddy Current Displacement Sensor (ECDS) is widely used in the Magnetic Suspension Flywheel (MSFW) to measure the tiny clearance between the rotor and the magnetic bearings. The linear range of the ECDS is determined by the diameter of its probe coil. Wide clearances must be measured in some new MSFWs recently designed for the different space missions, but the coil diameter is limited by some restrictions. In this paper, a multi-channel ECDS equipped with dual-coil probes is proposed to extend the linear range to satisfy the demands of such MSFWs. In order to determine the best configuration of the dual-coil probe, the quality factors of the potential types of the dual-coil probes, the induced eddy current and the magnetic intensity on the surface of the measuring object are compared with those of the conventional single-coil probe. The linear range of the ECDS equipped with the selected dual-coil probe is extended from 1.1 mm to 2.4 mm under the restrictions without adding any cost for additional compensation circuits or expensive coil materials. The effectiveness of the linear range extension ability and the dynamic response of the designed ECDS are confirmed by the testing and the applications in the MSFW.

  11. Antiparallel Four-Stranded Coiled Coil Specified by a 3-3-1 Hyrdrophobic Heptad Repeat

    SciTech Connect

    Deng,Y.; Liu, J.; Zheng, Q.; Eliezer, D.; Kallenbach, N.; Lu, M.

    2006-01-01

    Coiled-coil sequences in proteins commonly share a seven-amino acid repeat with nonpolar side chains at the first (a) and fourth (d) positions. We investigate here the role of a 3-3-1 hydrophobic repeat containing nonpolar amino acids at the a, d, and g positions in determining the structures of coiled coils using mutants of the GCN4 leucine zipper dimerization domain. When three charged residues at the g positions in the parental sequence are replaced by nonpolar alanine or valine side chains, stable four-helix structures result. The X-ray crystal structures of the tetramers reveal antiparallel, four-stranded coiled coils in which the a, d, and g side chains interlock in a combination of knobs-into-knobs and knobs-into-holes packing. Interfacial interactions in a coiled coil can therefore be prescribed by hydrophobic-polar patterns beyond the canonical 3-4 heptad repeat. The results suggest that the conserved, charged residues at the g positions in the GCN4 leucine zipper can impart a negative design element to disfavor thermodynamically more stable, antiparallel tetramers.

  12. Minimax current density gradient coils: analysis of coil performance and heating.

    PubMed

    Poole, Michael S; While, Peter T; Lopez, Hector Sanchez; Crozier, Stuart

    2012-08-01

    Standard gradient coils are designed by minimizing the inductance or resistance for an acceptable level of gradient field nonlinearity. Recently, a new method was proposed to minimize the maximum value of the current density in a coil additionally. The stated aim of that method was to increase the minimum wire spacing and to reduce the peak temperature in a coil for fixed efficiency. These claims are tested in this study with experimental measurements of magnetic field and temperature as well as simulations of the performance of many coils. Experimental results show a 90% increase in minimum wire spacing and 40% reduction in peak temperature for equal coil efficiency and field linearity. Simulations of many more coils indicate increase in minimum wire spacing of between 50 and 340% for the coils studied here. This method is shown to be able to increase coil efficiency when constrained by minimum wire spacing rather than switching times or total power dissipation. This increase in efficiency could be used to increase gradient strength, duty cycle, or buildability.

  13. An iterative method for coil sensitivity estimation in multi-coil MRI systems.

    PubMed

    Ling, Qiang; Li, Zhaohui; Song, Kaikai; Li, Feng

    2014-12-01

    This paper presents an iterative coil sensitivity estimation method for multi-coil MRI systems. The proposed method works with coil images in the magnitude image domain. It determines a region of support (RoS), a region being composed of the same type of tissues, by a region growing algorithm, which makes use of both intensities and intensity gradients of pixels. By repeating this procedure, it can determine multiple regions of support, which together cover most of the concerned image area. The union of these regions of support provides a rough estimate of the sensitivity of each coil through dividing the intensities of pixels by the average intensity inside every region of support. The obtained rough coil sensitivity estimate is further approached with the product of multiple low-order polynomials, rather than a single one. The product of these polynomials provides a smooth estimate of the sensitivity of each coil. With the obtained sensitivities of coils, it can produce a better reconstructed image, which determines more correct regions of support and yields preciser estimates of the sensitivities of coils. In other words, the method can be iteratively implemented to improve the estimation performance. The proposed method was verified through both simulated data and clinical data from different body parts. The experimental results confirm the superiority of our method to some conventional methods.

  14. Self-sorting heterodimeric coiled coil peptides with defined and tuneable self-assembly properties

    PubMed Central

    Aronsson, Christopher; Dånmark, Staffan; Zhou, Feng; Öberg, Per; Enander, Karin; Su, Haibin; Aili, Daniel

    2015-01-01

    Coiled coils with defined assembly properties and dissociation constants are highly attractive components in synthetic biology and for fabrication of peptide-based hybrid nanomaterials and nanostructures. Complex assemblies based on multiple different peptides typically require orthogonal peptides obtained by negative design. Negative design does not necessarily exclude formation of undesired species and may eventually compromise the stability of the desired coiled coils. This work describe a set of four promiscuous 28-residue de novo designed peptides that heterodimerize and fold into parallel coiled coils. The peptides are non-orthogonal and can form four different heterodimers albeit with large differences in affinities. The peptides display dissociation constants for dimerization spanning from the micromolar to the picomolar range. The significant differences in affinities for dimerization make the peptides prone to thermodynamic social self-sorting as shown by thermal unfolding and fluorescence experiments, and confirmed by simulations. The peptides self-sort with high fidelity to form the two coiled coils with the highest and lowest affinities for heterodimerization. The possibility to exploit self-sorting of mutually complementary peptides could hence be a viable approach to guide the assembly of higher order architectures and a powerful strategy for fabrication of dynamic and tuneable nanostructured materials. PMID:26370878

  15. Modified van Vaals-Bergman coaxial cable coil (lambda coil) for high-field imaging.

    PubMed

    Matsuzawa, H; Nakada, T

    1996-03-01

    An easily constructed, low-capacitive coupling volume coil based on the van Vaals-Bergman coaxial cable coil for high field imaging is described. The coil (designated "lambda coil") was constructed using two 5/4 length 50 omega coaxial cables matched to a 50 omega transmission line with LC bridge balun. The standing wave on the single 5/4 lambda length coaxial cable provides two points of current maxima in oppositional direction. Therefore, the four current elements necessary for effective B1 field generation can be obtained by two 5/4 lambda length coaxial cables arranged analogous to 1/2 lambda T-antenna. Capacitive coupling between the coil elements and conductive samples (i.e. animals) is minimized by simply retaining the shield of the coaxial cable for the area of voltage maxima. The lambda coil exhibited excellent performance as a volume coil with a high quality factor and highly homogeneous rf fields. Because of its dramatically simple architecture and excellent performance, the lambda coil configuration appears to be an economical alternative to the original van Vaals-Bergman design, especially for research facilities with a high field magnet and limited bore space.

  16. A high-resolution structure that provides insight into coiled-coil thiodepsipeptide dynamic chemistry.

    PubMed

    Dadon, Zehavit; Samiappan, Manickasundaram; Shahar, Anat; Zarivach, Raz; Ashkenasy, Gonen

    2013-09-16

    Stable and reactive: A crystal structure at 1.35 Å of a thioester coiled-coil protein reveals high similarity to all-peptide-bond proteins. In these assemblies, the thioester bonds are kept reactive towards thiol molecules in the mixture. This enables efficient domain exchange between proteins in response to changes in folding conditions or introduction of external templates.

  17. Allosteric effects in coiled-coil proteins folding and lanthanide-ion binding.

    PubMed

    Samiappan, Manickasundaram; Alasibi, Samaa; Cohen-Luria, Rivka; Shanzer, Abraham; Ashkenasy, Gonen

    2012-10-07

    Peptide sequences modified with lanthanide-chelating groups at their N-termini, or at their lysine side chains, were synthesized, and new Ln(III) complexes were characterized. We show that partial folding of the conjugates to form trimer coiled coil structures induces coordination of lanthanides to the ligand, which in turn further stabilizes the 3D structure.

  18. Teaching real-time ultrasonic imaging with a 4-channel sonar array, TI C6711 DSK and MATLAB.

    PubMed

    York, George W P; Welch, Thad B; Wright, Cameron H G

    2005-01-01

    Ultrasonic medical imaging courses often stop at the theory or MATLAB simulation level, since professors find it challenging to give the students the experience of designing a real-time ultrasonic system. Some of the practical problems of working with real-time data from the ultrasonic transducers can be avoided by working at lower frequencies (sonar to low ultrasound) range. To facilitate this, we have created a platform using the ease of MATLAB programming with the real-time processing capability of the low-cost Texas Instruments C6711 DSP starter kit and a 4-channel sonar array. With this platform students can design a B-mode or Color-Mode sonar system in the MATLAB environment. This paper will demonstrate how the platform can be used in the classroom to demonstrate the real-time signal processing stages including beamforming, multi-rate sampling, demodulation, filtering, image processing, echo imaging, and Doppler frequency estimation.

  19. Graphene-coated coupling coil for AC resistance reduction

    SciTech Connect

    Miller, John M

    2014-03-04

    At least one graphene layer is formed to laterally surround a tube so that the basal plane of each graphene layer is tangential to the local surface of the tube on which the graphene layer is formed. An electrically conductive path is provided around the tube for providing high conductivity electrical path provided by the basal plane of each graphene layer. The high conductivity path can be employed for high frequency applications such as coupling coils for wireless power transmission to overcome skin depth effects and proximity effects prevalent in high frequency alternating current paths.

  20. Functionally active t1-t1 interfaces revealed by the accessibility of intracellular thiolate groups in kv4 channels.

    PubMed

    Wang, Guangyu; Shahidullah, Mohammad; Rocha, Carmen A; Strang, Candace; Pfaffinger, Paul J; Covarrubias, Manuel

    2005-07-01

    Gating of voltage-dependent K(+) channels involves movements of membrane-spanning regions that control the opening of the pore. Much less is known, however, about the contributions of large intracellular channel domains to the conformational changes that underlie gating. Here, we investigated the functional role of intracellular regions in Kv4 channels by probing relevant cysteines with thiol-specific reagents. We find that reagent application to the intracellular side of inside-out patches results in time-dependent irreversible inhibition of Kv4.1 and Kv4.3 currents. In the absence or presence of Kv4-specific auxiliary subunits, mutational and electrophysiological analyses showed that none of the 14 intracellular cysteines is essential for channel gating. C110, C131, and C132 in the intersubunit interface of the tetramerization domain (T1) are targets responsible for the irreversible inhibition by a methanethiosulfonate derivative (MTSET). This result is surprising because structural studies of Kv4-T1 crystals predicted protection of the targeted thiolate groups by constitutive high-affinity Zn(2+) coordination. Also, added Zn(2+) or a potent Zn(2+) chelator (TPEN) does not significantly modulate the accessibility of MTSET to C110, C131, or C132; and furthermore, when the three critical cysteines remained as possible targets, the MTSET modification rate of the activated state is approximately 200-fold faster than that of the resting state. Biochemical experiments confirmed the chemical modification of the intact alpha-subunit and the purified tetrameric T1 domain by MTS reagents. These results conclusively demonstrate that the T1--T1 interface of Kv4 channels is functionally active and dynamic, and that critical reactive thiolate groups in this interface may not be protected by Zn(2+) binding.

  1. Functionally Active T1-T1 Interfaces Revealed by the Accessibility of Intracellular Thiolate Groups in Kv4 Channels

    PubMed Central

    Wang, Guangyu; Shahidullah, Mohammad; Rocha, Carmen A.; Strang, Candace; Pfaffinger, Paul J.; Covarrubias, Manuel

    2005-01-01

    Gating of voltage-dependent K+ channels involves movements of membrane-spanning regions that control the opening of the pore. Much less is known, however, about the contributions of large intracellular channel domains to the conformational changes that underlie gating. Here, we investigated the functional role of intracellular regions in Kv4 channels by probing relevant cysteines with thiol-specific reagents. We find that reagent application to the intracellular side of inside-out patches results in time-dependent irreversible inhibition of Kv4.1 and Kv4.3 currents. In the absence or presence of Kv4-specific auxiliary subunits, mutational and electrophysiological analyses showed that none of the 14 intracellular cysteines is essential for channel gating. C110, C131, and C132 in the intersubunit interface of the tetramerization domain (T1) are targets responsible for the irreversible inhibition by a methanethiosulfonate derivative (MTSET). This result is surprising because structural studies of Kv4-T1 crystals predicted protection of the targeted thiolate groups by constitutive high-affinity Zn2+ coordination. Also, added Zn2+ or a potent Zn2+ chelator (TPEN) does not significantly modulate the accessibility of MTSET to C110, C131, or C132; and furthermore, when the three critical cysteines remained as possible targets, the MTSET modification rate of the activated state is ∼200-fold faster than that of the resting state. Biochemical experiments confirmed the chemical modification of the intact α-subunit and the purified tetrameric T1 domain by MTS reagents. These results conclusively demonstrate that the T1–T1 interface of Kv4 channels is functionally active and dynamic, and that critical reactive thiolate groups in this interface may not be protected by Zn2+ binding. PMID:15955876

  2. Crystalline tubes of myosin subfragment-2 showing the coiled-coil and molecular interaction geometry

    PubMed Central

    1987-01-01

    We have produced crystalline tubes of chicken breast myosin long subfragment-2 that show order to resolutions better than 2 nm. The tubes were formed from a thin sheet in which the myosin long subfragment-2 molecules were arranged on an approximately rectangular crystalline lattice with a = 14.1 +/- 0.2 nm and b = 3.9 +/- 0.1 nm in projection. Shadowing indicated that the tube wall was approximately 7 nm thick and that the sheets from which it was formed followed a right- handed helix. Superposition of the lattices from the top and bottom of the tube produced a moire pattern in negatively stained material, but images of single sheets were easily obtained by computer image processing. Although several molecules were superimposed perpendicular to the plane of the sheet, the modulation in density due to the coiled- coil envelope was clear, indicating that the coiled-coils in these molecules were in register (or staggered by an even number of quarter pitches). In projection the coiled-coil had an apparent pitch of 14.1 nm (the axial repeat of the unit cell), but the small number of molecules (probably four) superimposed perpendicular to the plane of the sheet meant that pitches within approximately 1 nm of this value could have shown a modulation. Therefore, a more precise determination of the coiled-coil pitch must await determination of the sheet's three- dimensional structure. The coiled-coils of adjacent molecules within the plane of the sheet were staggered by an odd number of quarter pitches. This arrangement was similar to that between paramyosin molecules in molluscan thick filaments and may have features in common with other coiled-coil protein assemblies, such as intermediate filaments. Each molecule in the crystal had two types of neighbor: one staggered by an odd number of quarter pitches and the other by an even number of quarter pitches, as has been proposed for the general packing of coiled-coils (Longley, W., 1975, J. Mol. Biol., 93:111-115). We propose

  3. Coil in coil - components for the high voltage superconducting resistive current limiter CULT 110

    NASA Astrophysics Data System (ADS)

    Elschner, S.; Stemmle, M.; Breuer, F.; Walter, H.; Frohne, C.; Noe, M.; Bock, J.

    2008-02-01

    The German government (BMBF/VDI) funded project CULT 110 is presently the largest European current limiter project and aims at the development of a one-phase resistive limiter for the voltage level of 110 kV. The contribution presents the actual state of development of the superconducting components. As in the successful predecessor project CURL 10 these are made of melt cast processed BSCCO 2212 bulk material, however monofilar instead of bifilar coils are used. The electrical protection concept is based on a normal conducting coil arranged around a superconducting coil and connected in parallel. Simultaneously this coil serves as an electrical bypass and, under fault conditions, generates a magnetic field for quench homogenisation. Since no continuously connected shunt is needed, a much higher voltage during faults can be applied. The rules for an optimum superconductor and coil design are given and the viability of the whole concept is demonstrated by both, experiment and numerical simulation.

  4. Baculovirus FP25K Localization: Role of the Coiled-Coil Domain.

    PubMed

    Garretson, Tyler A; McCoy, Jason C; Cheng, Xiao-Wen

    2016-11-01

    Two types of viruses are produced during the baculovirus life cycle: budded virus (BV) and occlusion-derived virus (ODV). A particular baculovirus protein, FP25K, is involved in the switch from BV to ODV production. Previously, FP25K from the model alphabaculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) was shown to traffic ODV envelope proteins. However, FP25K localization and the domains involved are inconclusive. Here we used a quantitative approach to study FP25K subcellular localization during infection using an AcMNPV bacmid virus that produces a functional AcMNPV FP25K-green fluorescent protein (GFP) fusion protein. During cell infection, FP25K-GFP localized primarily to the cytoplasm, particularly amorphous structures, with a small fraction being localized in the nucleus. To investigate the sequences involved in FP25K localization, an alignment of baculovirus FP25K sequences revealed that the N-terminal putative coiled-coil domain is present in all alphabaculoviruses but absent in betabaculoviruses. Structural prediction indicated a strong relatedness of AcMNPV FP25K to long interspersed element 1 (LINE-1) open reading frame 1 protein (ORF1p), which contains an N-terminal coiled-coil domain responsible for cytoplasmic retention. Point mutations and deletions of this domain lead to a change in AcMNPV FP25K localization from cytoplasmic to nuclear. The coiled-coil and C-terminal deletion viruses increased BV production. Furthermore, a betabaculovirus FP25K protein lacking this N-terminal coiled-coil domain localized predominantly to the nucleus and exhibited increased BV production. These data suggest that the acquisition of this N-terminal coiled-coil domain in FP25K is important for the evolution of alphabaculoviruses. Moreover, with the divergence of preocclusion nuclear membrane breakdown in betabaculoviruses and membrane integrity in alphabaculoviruses, this domain represents an alphabaculovirus adaptation for nuclear trafficking

  5. Automated de novo phasing and model building of coiled-coil proteins.

    PubMed

    Rämisch, Sebastian; Lizatović, Robert; André, Ingemar

    2015-03-01

    Models generated by de novo structure prediction can be very useful starting points for molecular replacement for systems where suitable structural homologues cannot be readily identified. Protein-protein complexes and de novo-designed proteins are examples of systems that can be challenging to phase. In this study, the potential of de novo models of protein complexes for use as starting points for molecular replacement is investigated. The approach is demonstrated using homomeric coiled-coil proteins, which are excellent model systems for oligomeric systems. Despite the stereotypical fold of coiled coils, initial phase estimation can be difficult and many structures have to be solved with experimental phasing. A method was developed for automatic structure determination of homomeric coiled coils from X-ray diffraction data. In a benchmark set of 24 coiled coils, ranging from dimers to pentamers with resolutions down to 2.5 Å, 22 systems were automatically solved, 11 of which had previously been solved by experimental phasing. The generated models contained 71-103% of the residues present in the deposited structures, had the correct sequence and had free R values that deviated on average by 0.01 from those of the respective reference structures. The electron-density maps were of sufficient quality that only minor manual editing was necessary to produce final structures. The method, named CCsolve, combines methods for de novo structure prediction, initial phase estimation and automated model building into one pipeline. CCsolve is robust against errors in the initial models and can readily be modified to make use of alternative crystallographic software. The results demonstrate the feasibility of de novo phasing of protein-protein complexes, an approach that could also be employed for other small systems beyond coiled coils.

  6. The effect of scleral search coil lens wear on the eye

    PubMed Central

    Murphy, P.; Duncan, A.; Glennie, A.; Knox, P.

    2001-01-01

    BACKGROUND/AIM—Scleral search coils are used to measure eye movements. A recent abstract suggests that the coil can affect the eye by decreasing visual acuity, increasing intraocular pressure, and damaging the corneal and conjunctival surface. Such findings, if repeated in all subjects, would cast doubt on the credibility of the search coil as a reliable investigative technique. The aim of this study was to reassess the effect of the scleral search coil on visual function.
METHODS—Six volunteer subjects were selected to undergo coil wear and baseline measurements were taken of logMAR visual acuity, non-contact tonometry, keratometry, and slit lamp examination. Four drops of 0.4% benoxinate hydrochloride were instilled before insertion of the lens by an experienced clinician. The lens then remained on the eye for 30 minutes. Measurements of the four ocular health parameters were repeated after 15 and 30 minutes of lens wear. The lens was then removed and the health of the eye reassessed.
RESULTS—No obvious pattern of change was found in logMAR visual acuity, keratometry, or intraocular pressure. The lens did produce changes to the conjunctival and corneal surfaces, but this was not considered clinically significant.
CONCLUSION—Search coils do not appear to cause any significant effects on visual function. However, thorough prescreening of subjects and post-wear checks should be carried out on all coil wearers to ensure no adverse effects have been caused.

 PMID:11222341

  7. Magnetic-field sensing coil embedded in ceramic for measuring ambient magnetic field

    DOEpatents

    Takahashi, Hironori

    2004-02-10

    A magnetic pick-up coil for measuring magnetic field with high specific sensitivity, optionally with an electrostatic shield (24), having coupling elements (22) with high winding packing ratio, oriented in multiple directions, and embedded in ceramic material for structural support and electrical insulation. Elements of the coil are constructed from green ceramic sheets (200) and metallic ink deposited on surfaces and in via holes of the ceramic sheets. The ceramic sheets and the metallic ink are co-fired to create a monolithic hard ceramic body (20) with metallized traces embedded in, and placed on exterior surfaces of, the hard ceramic body. The compact and rugged coil can be used in a variety of environments, including hostile conditions involving ultra-high vacuum, high temperatures, nuclear and optical radiation, chemical reactions, and physically demanding surroundings, occurring either individually or in combinations.

  8. B(1) destructive interferences and spatial phase patterns at 7 T with a head transceiver array coil.

    PubMed

    Van de Moortele, Pierre-François; Akgun, Can; Adriany, Gregor; Moeller, Steen; Ritter, Johannes; Collins, Christopher M; Smith, Michael B; Vaughan, J Thomas; Uğurbil, Kāmil

    2005-12-01

    RF behavior in the human head becomes complex at ultrahigh magnetic fields. A bright center and a weak periphery are observed in images obtained with volume coils, while surface coils provide strong signal in the periphery. Intensity patterns reported with volume coils are often loosely referred to as "dielectric resonances," while modeling studies ascribe them to superposition of traveling waves greatly dampened in lossy brain tissues, raising questions regarding the usage of this term. Here we address this question experimentally, taking full advantage of a transceiver coil array that was used in volume transmit mode, multiple receiver mode, or single transmit surface coil mode. We demonstrate with an appropriately conductive sphere phantom that destructive interferences are responsible for a weak B(1) in the periphery, without a significant standing wave pattern. The relative spatial phase of receive and transmit B(1) proved remarkably similar for the different coil elements, although with opposite rotational direction. Additional simulation data closely matched our phantom results. In the human brain the phase patterns were more complex but still exhibited similarities between coil elements. Our results suggest that measuring spatial B(1) phase could help, within an MR session, to perform RF shimming in order to obtain more homogeneous B(1) in user-defined areas of the brain.

  9. Coil system for a mirror-based hybrid reactor

    SciTech Connect

    Hagnestal, A.; Agren, O.; Moiseenko, V. E.

    2012-06-19

    Two different superconducting coil systems for the SFLM Hybrid study - a quadrupolar mirror based fusion-fission reactor study - are presented. One coil system is for a magnetic field with 2 T at the midplane and a mirror ratio of four. This coil set consists of semiplanar coils in two layers. The alternative coil system is for a downscaled magnetic field of 1.25 T at the midplane and a mirror ratio of four, where a higher {beta} is required to achieve sufficient the neutron production. This coil set has one layer of twisted 3D coils. The 3D coils are expected to be considerably cheaper than the semiplanar, since NbTi superconductors can be used for most coils instead of Nb3Sn due to the lower magnetic field.

  10. Hydrogel-Coated Coils: Product Description and Clinical Applications

    PubMed Central

    Ferral, Hector

    2015-01-01

    Hydrogel-coated coils are truly detachable coils with a platinum core covered with hydrogel. The coils are available in 0.018- and 0.035-in systems. These coils have the ability to expand up to four times their size ∼20 minutes after deployment, thus providing a very effective mechanical vascular occlusion effect. The vessel-occlusive effect of these coils is a volume, space-occupying effect, not a thrombotic effect, as seen in fibered coils. Hydrogel-coated coils were originally developed and designed to treat brain aneurysms; however, their use has expanded to peripheral applications. Hydrogel-coated coils have been used in the management of visceral aneurysms, high-flow vascular arteriovenous fistulae, and endoleaks after endovascular thoracic and abdominal aneurysm repair. The purpose of this article is to describe the hydrogel-coated coil system, the mechanism of action, technical details for optimal deployment, and clinical applications. PMID:26622096

  11. Coupled wave model for large magnet coils

    NASA Technical Reports Server (NTRS)

    Gabriel, G. J.

    1980-01-01

    A wave coupled model based on field theory is evolved for analysis of fast electromagnetic transients on superconducting coils. It is expected to play a useful role in the design of protection methods against damage due to high voltages or any adverse effects that might arise from unintentional transients. The significant parameters of the coil are identified to be the turn to turn wave coupling coefficients and the travel time of an electromagnetic disturbance around a single turn. Unlike circuit theoretic inductor, the coil response evolves in discrete steps having durations equal to this travel time. It is during such intervals that high voltages are likely to occur. The model also bridges the gap between the low and high ends of the frequency spectrum.

  12. Coil occlusion of a subclavian mycotic aneurysm.

    PubMed

    Kische, Stephan; Ince, Hüseyin; Peuster, Matthias

    2010-06-01

    We report the first successful application of nonferromagnetic embolization coils for endovascular exclusion of a mycotic right subclavian artery aneurysm. A 58-year-old woman presented with acute cervical pain and a pulsatile mass in the right supraclavicular fossa under antibiotic medication for subacute infectious endocarditis. Diagnostic work-up including duplex sonography, digital subtraction angiography, and magnetic resonance imaging demonstrated a saccular aneurysm of the extrathoracic right subclavian artery. As an alternative to open surgery or stent-graft repair, this pathology was electively treated by transcatheter coil embolization. No neurological deficit or ischemic symptoms were noted during 9 months clinical follow-up. Multislice computed tomography scan revealed complete occlusion of the mycotic aneurysm 6 months after the interventional procedure. Transcatheter closure with Inconel embolization coils is a cost-effective and safe therapeutic option in patients with mycotic aneurysm originating from the subclavian artery.

  13. Measuring the orthogonality error of coil systems

    USGS Publications Warehouse

    Heilig, B.; Csontos, A.; Pajunpää, K.; White, Tim; St. Louis, B.; Calp, D.

    2012-01-01

    Recently, a simple method was proposed for the determination of pitch angle between two coil axes by means of a total field magnetometer. The method is applicable when the homogeneous volume in the centre of the coil system is large enough to accommodate the total field sensor. Orthogonality of calibration coil systems used for calibrating vector magnetometers can be attained by this procedure. In addition, the method can be easily automated and applied to the calibration of delta inclination–delta declination (dIdD) magnetometers. The method was tested by several independent research groups, having a variety of test equipment, and located at differing geomagnetic observatories, including: Nurmijärvi, Finland; Hermanus, South Africa; Ottawa, Canada; Tihany, Hungary. This paper summarizes the test results, and discusses the advantages and limitations of the method.

  14. Considerations against a force compensated coil

    SciTech Connect

    Hassenzahl, W.

    1988-08-01

    The cost of structural components in a large superconducting coil may well exceed the coil and cryostat cost. As a result, the idea of constructing a system composed of two different coil types assembled in such a way that the sources balance and reduce the total structural requirement is oft proposed. A suitable geometry has never been found for the fundamental reason that there can be no force compensated solution. In this paper, the general problem is presented and an analysis of the energy stored and stresses produced in the structure are described in a fundamental way. Finally, the relation between structural mass M and stored energy E, M greater than or equal to/rho/E/sigma/sub w/, that is valid for all magnetic systems is developed, where /rho/ is the density of the structure and sigma/sub w/ is the working stress in the structure. 12 refs., 2 figs.

  15. Acoustic rainbow trapping by coiling up space

    NASA Astrophysics Data System (ADS)

    Ni, Xu; Wu, Ying; Chen, Ze-Guo; Zheng, Li-Yang; Xu, Ye-Long; Nayar, Priyanka; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yan-Feng

    2014-11-01

    We numerically realize the acoustic rainbow trapping effect by tapping an air waveguide with space-coiling metamaterials. Due to the high refractive-index of the space-coiling metamaterials, our device is more compact compared to the reported trapped-rainbow devices. A numerical model utilizing effective parameters is also calculated, whose results are consistent well with the direct numerical simulation of space-coiling structure. Moreover, such device with the capability of dropping different frequency components of a broadband incident temporal acoustic signal into different channels can function as an acoustic wavelength division de-multiplexer. These results may have potential applications in acoustic device design such as an acoustic filter and an artificial cochlea.

  16. Gas Filled Coaxial Accelerator with Compression Coil

    NASA Technical Reports Server (NTRS)

    Espy, Patrick N. (Inventor)

    1976-01-01

    A self-energized plasma compressor which compresses plasma discharged from a coaxial plasma generator. The device includes a helical shaped coil which is coaxially aligned with the center axis of the coaxial plasma generator. The plasma generator creates a current through the helical coil which, in turn, generates a time varying magnetic field that generates a force which acts radially upon the plasma. A seal is carried on the end of the coaxial plasma generator for containing gas therein. As the plasma is accelerated out the outer end of the generator, it forces the gas outwardly also compressing such. Beads are carried adjacent the small end of the helical shaped coil for being accelerated to hypervelocities by the plasma and gas. As a result of utilizing gas in the coaxial plasma generator, such minimizes ablation of the beads as well as accelerates such to higher velocities.

  17. Subacute hypoxia suppresses Kv3.4 channel expression and whole-cell K+ currents through endogenous 15-hydroxyeicosatetraenoic acid in pulmonary arterial smooth muscle cells.

    PubMed

    Guo, Lei; Tang, Xiaobo; Tian, Hua; Liu, Ye; Wang, Zhigang; Wu, Hong; Wang, Jing; Guo, Sholi; Zhu, Daling

    2008-06-10

    We have previously reported that subacute hypoxia activates lung 15-lipoxygenase (15-LOX), which catalyzes arachidonic acid to produce 15-HETE, leading to constriction of neonatal rabbit pulmonary arteries. Subacute hypoxia suppresses Kv3.4 channel expression and results in an inhibition of whole-cell K(+) currents (I(K)). Although the Kv channel inhibition is likely to be mediated through 15-HETE, direct evidence is still lacking. To reveal the role of the 15-LOX/15-HETE pathway in the hypoxia-induced down-regulation of Kv3.4 channel expression and inhibition of I(K), we performed studies using 15-LOX blockers, whole-cell patch-clamp, semi-quantitative PCR, ELISA and Western blot analysis. We found that Kv3.4 channel expression at the mRNA and protein levels was greatly up-regulated in pulmonary arterial smooth muscle cells after blockade of 15-LOX by CDC or NDGA. The 15-LOX blockade also partially restored I(K). In comparison, 15-HETE had a stronger effect than 12-HETE on the expression of Kv3.4 channels. 5-HETE had no noticeable effect on Kv3.4 channel expression. These data indicate that the 15-LOX pathway via its metabolite, 15-HETE, seems to play a role in the down-regulation of Kv3.4 expression and I(K) inhibition after subacute hypoxia.

  18. Coiled tubing buckling implication in drilling and completing horizontal wells

    SciTech Connect

    Wu, J.; Juvkam-Wold, H.C.

    1995-03-01

    This paper discusses coiled tubing buckling and load transmission when drilling and completing horizontal wells. Comprehensive analyses and new equations are presented to predict buckling of coiled tubing, slack-off weight transmission, actual bit weight or packer load, and maximum horizontal length. Coiled tubing lock-up and yield due to buckling are also discussed. These equations can also be used for other coiled tubing operations, such as coiled tubing workover, coiled tubing well stimulation, and even for conventional joint-connected drill strings. Calculations based on the equations presented are also compared with the previous literature.

  19. Resistive demountable toroidal-field coils for tokamak reactors

    SciTech Connect

    Jassby, D.L.; Jacobsen, R.A.; Kalnavarns, J.; Masson, L.S.; Sekot, J.P.

    1981-07-01

    Readily demountable TF (toroidal-field) coils allow complete access to the internal components of a tokamak reactor for maintenance of replacement. The requirement of readily demountable joints dictates the use of water-cooled resistive coils, which have a host of decisive advantages over superconducting coils. Previous papers have shown that resistive TF coils for tokamak reactors can operate in the steady state with acceptable power dissipation (typically, 175 to 300 MW). This paper summarizes results of parametric studies of size optimization of rectangular TF coils and of a finite-element stress analysis, and examines several candidate methods of implementing demountable joints for rectangular coils constructed of plate segments.

  20. Analytical and experimental analysis of tube coil heat exchanger

    NASA Astrophysics Data System (ADS)

    Smusz, R.

    2016-09-01

    The paper presents the analytical and experimental analysis of heat transfer for the finned tube coil heat exchanger immersed in thermal storage tank. The tank is equipped with three helical-shaped heating coils and cylindrical- shaped stratification device. Two coils, upper and lower, use the water as a heating medium. The third, double wall heat exchanger coil, located at the bottom head on the tank is filled by the refrigerant (freon). Calculations of thermal power of water coil were made. Correlations of heat transfer coefficients in curved tubes were applied. In order to verify the analytical calculations the experimental studies of heat transfer characteristic for coil heat exchanger were performed.

  1. Coiled coil interactions for the targeting of liposomes for nucleic acid delivery

    NASA Astrophysics Data System (ADS)

    Oude Blenke, Erik E.; van den Dikkenberg, Joep; van Kolck, Bartjan; Kros, Alexander; Mastrobattista, Enrico

    2016-04-01

    Coiled coil interactions are strong protein-protein interactions that are involved in many biological processes, including intracellular trafficking and membrane fusion. A synthetic heterodimeric coiled-coil forming peptide pair, known as E3 (EIAALEK)3 and K3 (KIAALKE)3 was used to functionalize liposomes encapsulating a splice correcting oligonucleotide or siRNA. These peptide-functionalized vesicles are highly stable in solution but start to cluster when vesicles modified with complementary peptides are mixed together, demonstrating that the peptides quickly coil and crosslink the vesicles. When one of the peptides was anchored to the cell membrane using a hydrophobic cholesterol anchor, vesicles functionalized with the complementary peptide could be docked to these cells, whereas non-functionalized cells did not show any vesicle tethering. Although the anchored peptides do not have a downstream signaling pathway, microscopy pictures revealed that after four hours, the majority of the docked vesicles were internalized by endocytosis. Finally, for the first time, it was shown that the coiled coil assembly at the interface between the vesicles and the cell membrane induces active uptake and leads to cytosolic delivery of the nucleic acid cargo. Both the siRNA and the splice correcting oligonucleotide were functionally delivered, resulting respectively in the silencing or recovery of luciferase expression in the appropriate cell lines. These results demonstrate that the docking to the cell by coiled coil interaction can induce active uptake and achieve the successful intracellular delivery of otherwise membrane impermeable nucleic acids in a highly specific manner.Coiled coil interactions are strong protein-protein interactions that are involved in many biological processes, including intracellular trafficking and membrane fusion. A synthetic heterodimeric coiled-coil forming peptide pair, known as E3 (EIAALEK)3 and K3 (KIAALKE)3 was used to functionalize liposomes

  2. Self-assembling segmented coiled tubing

    DOEpatents

    Raymond, David W.

    2016-09-27

    Self-assembling segmented coiled tubing is a concept that allows the strength of thick-wall rigid pipe, and the flexibility of thin-wall tubing, to be realized in a single design. The primary use is for a drillstring tubular, but it has potential for other applications requiring transmission of mechanical loads (forces and torques) through an initially coiled tubular. The concept uses a spring-loaded spherical `ball-and-socket` type joint to interconnect two or more short, rigid segments of pipe. Use of an optional snap ring allows the joint to be permanently made, in a `self-assembling` manner.

  3. Superconductor coil geometry and ac losses

    NASA Technical Reports Server (NTRS)

    Pierce, T. V., Jr.; Zapata, R. N.

    1976-01-01

    An empirical relation is presented which allows simple computation of volume-averaged winding fields from central fields for coils of small rectangular cross sections. This relation suggests that, in certain applications, ac-loss minimization can be accomplished by use of low winding densities, provided that hysteresis losses are independent of winding density. The ac-loss measurements on coils wound of twisted multifilamentary composite superconductors show no significant dependence on ac losses on winding density, thus permitting the use of winding density as an independent design parameter in loss minimization.

  4. High-Efficiency Helical Coil Electromagnetic Launcher

    DTIC Science & Technology

    2006-08-31

    partly supported by the research include C. Keawboonchuay (PhD), S. Huenefeldt (MS), S. Rohe (MS), C. Nunnally (PhD). Faculty include T.G. Engel, W.C...Magnetics, vol. 42, no. 8, pp 2043 - 2051, 2006. 2. T.G. Engel and S. Rohe , "A comparison of single-layer coaxial coil mutual inductance calculations... Rohe , "Investigation of the accuracy of Grover’s method when solving for the mutual inductance of two single-layer coaxial coils," MS Thesis

  5. Superconducting Coil Winding Machine Control System

    SciTech Connect

    Nogiec, J. M.; Kotelnikov, S.; Makulski, A.; Walbridge, D.; Trombly-Freytag, K.

    2016-10-05

    The Spirex coil winding machine is used at Fermilab to build coils for superconducting magnets. Recently this ma-chine was equipped with a new control system, which al-lows operation from both a computer and a portable remote control unit. This control system is distributed between three layers, implemented on a PC, real-time target, and FPGA, providing respectively HMI, operational logic and direct controls. The system controls motion of all mechan-ical components and regulates the cable tension. Safety is ensured by a failsafe, redundant system.

  6. Cooling a solar telescope enclosure: plate coil thermal analysis

    NASA Astrophysics Data System (ADS)

    Gorman, Michael; Galapon, Chriselle; Montijo, Guillermo; Phelps, LeEllen; Murga, Gaizka

    2016-08-01

    The climate of Haleakalā requires the observatories to actively adapt to changing conditions in order to produce the best possible images. Observatories need to be maintained at a temperature closely matching ambient or the images become blurred and unusable. The Daniel K. Inouye Solar Telescope is a unique telescope as it will be active during the day as opposed to the other night-time stellar observatories. This means that it will not only need to constantly match the ever-changing temperature during the day, but also during the night so as not to sub-cool and affect the view field of other telescopes while they are in use. To accomplish this task, plate coil heat exchanger panels will be installed on the DKIST enclosure that are designed to keep the temperature at ambient temperature +0°C/-4°C. To verify the feasibility of this and to validate the design models, a test rig has been installed at the summit of Haleakalā. The project's purpose is to confirm that the plate coil panels are capable of maintaining this temperature throughout all seasons and involved collecting data sets of various variables including pressures, temperatures, coolant flows, solar radiations and wind velocities during typical operating hours. Using MATLAB, a script was written to observe the plate coil's thermal performance. The plate coil did not perform as expected, achieving a surface temperature that was generally 2ºC above ambient temperature. This isn't to say that the plate coil does not work, but the small chiller used for the experiment was undersized resulting in coolant pumped through the plate coil that was not supplied at a low enough temperature. Calculated heat depositions were about 23% lower than that used as the basis of the design for the hillers to be used on the full system, a reasonable agreement given the fact that many simplifying assumptions were used in the models. These were not carried over into the testing. The test rig performance showing a 23% margin

  7. Characteristics of bowl-shaped coils for transcranial magnetic stimulation

    NASA Astrophysics Data System (ADS)

    Yamamoto, Keita; Suyama, Momoko; Takiyama, Yoshihiro; Kim, Dongmin; Saitoh, Youichi; Sekino, Masaki

    2015-05-01

    Transcranial magnetic stimulation (TMS) has recently been used as a method for the treatment of neurological and psychiatric diseases. Daily TMS sessions can provide continuous therapeutic effectiveness, and the installation of TMS systems at patients' homes has been proposed. A figure-eight coil, which is normally used for TMS therapy, induces a highly localized electric field; however, it is challenging to achieve accurate coil positioning above the targeted brain area using this coil. In this paper, a bowl-shaped coil for stimulating a localized but wider area of the brain is proposed. The coil's electromagnetic characteristics were analyzed using finite element methods, and the analysis showed that the bowl-shaped coil induced electric fields in a wider area of the brain model than a figure-eight coil. The expanded distribution of the electric field led to greater robustness of the coil to the coil-positioning error. To improve the efficiency of the coil, the relationship between individual coil design parameters and the resulting coil characteristics was numerically analyzed. It was concluded that lengthening the outer spherical radius and narrowing the width of the coil were effective methods for obtaining a more effective and more uniform distribution of the electric field.

  8. Apparatus for operating a downhole tool using coil tubing

    SciTech Connect

    Perricone, J.M.

    1992-03-17

    This patent describes a packer for running on coiled tubing inside a well tubing that can be set by reciprocation of the tubing. It comprises a mandrel for attaching to the end of the coiled tubing, a lower packer head attached to the mandrel, an annular packing element on the mandrel supported by the packer head, an upper packer head having a conical outer surface, a slip assembly carried by the mandrel and including slips and means for engaging the well tubing and frictionally resisting movement of the slip means through the well casing, and means connecting the slip assembly to the mandrel to limit upward movement of the slip means relative to the mandrel as the packer is being run into the well tubing and upon reciprocation of the mandrel for allowing the mandrel to move upwardly moving the outer conical surface of the upper packer head under the slips forcing the slips into engagement with the well tubing to hold the upper packer head against further upward movement to allow continued upward movement of the mandrel to compress the packing element between the upper and lower packer heads and force the packing element into sealing engagement with the mandrel and the well tubing.

  9. Multiaxial plasticity and fatigue life prediction in coiled tubing

    SciTech Connect

    Tipton, S.M.

    1996-12-31

    Coiled tubing is being used increasingly in the oil well drilling and servicing industry. Continuous steel tubing of structural dimensions (up to 89 mm or 3.5 in. in diameter) is wound onto a large-diameter reel for repeated deployment into and out of a well bore. The bending strain range associated with each wrap-unwrap cycle can exceed 3% with lives well below 100 cycles. During constant internal pressure fatigue testing, tubing has been observed to grow in diameter by as much as 30%. This paper describes an analytical model to predict the fatigue behavior of coiled tubing subjected to variable pressure service conditions. The approach utilizes standard low-cycle fatigue data but requires additional experimental results from constant pressure fatigue testing. The algorithm is based on estimates of biaxial ratcheting from an incremental plasticity model using a hybrid associated flow rule, a modified kinematic hardening rule with multiple von Mises yield surfaces, and a specialized limit surface concept. An empirical damage parameter was formulated based on constant pressure fatigue data using mean and fluctuating von Mises equivalent strain components occurring throughout the life of a section of tubing. This parameters is used with the Palmgren-Miner definition of cumulative damage to track damage that is accumulating nonlinearly under constant or variable pressure histories. Modifications to standard incremental plasticity components and implementation assumptions used to apply the model are presented and discussed. The predictive capability of the model is demonstrated relative to data generated under constant and variable pressure histories.

  10. Differential efficacy of GoSlo-SR compounds on BKα and BKαγ1-4 channels.

    PubMed

    Kshatri, Aravind S; Li, Qin; Yan, Jiusheng; Large, Roddy J; Sergeant, Gerard P; McHale, Noel G; Thornbury, Keith D; Hollywood, Mark A

    2017-01-02

    Large conductance, voltage and Ca(2+) activated K(+) channels (BK channels) are abundantly expressed throughout the body and are important regulators of smooth muscle tone and neuronal excitability. Their dysfunction is implicated in various diseases including overactive bladder, hypertension and erectile dysfunction. Therefore, BK channel openers bear significant therapeutic potential to treat the above diseases. GoSlo-SR compounds were designed to be potent and efficacious BK channel openers. Although their structural activity relationships, activation in both BKα and BKαβ channels and the hypothetical mode of action of these compounds has been studied in detail in recent years, their effectiveness to open the BKαγ channels still remains unexplored. In this study, we have examined the efficacy of 3 closely related GoSlo-SR openers, GoSlo-SR-5-6 (SR-5-6), GoSlo-SR-5-44 (SR-5-44) and GoSlo-SR-5-130 (SR-5-130) using inside out patches on BKα channels coexpressed with 4 different LRRC (γ1-4) subunits in HEK293 cells. Our data suggests that the activation effects due to SR-5-6 were not significantly affected in the presence of γ1-4 subunits. Interestingly, the effects of more efficacious BK channel opener SR-5-44 were altered by different γ subunits. In cells expressing BKα channels, the shift in V1/2 (ΔV1/2) induced by SR-5-44 (3 μM) was -76 ± 3 mV, whereas it was significantly reduced by ∼70 % in BKαγ1 channels (ΔV1/2= -23 ± 3, p < 0.001, ANOVA). In BKαγ2 channels the ΔV1/2 was -36 ± 1 mV, which was less than that observed in BKαγ3 and BKαγ4 channels where the ΔV1/2 was -47 ± 5 mV, and -82 ± 5 mV, respectively. Additionally, the excitatory effects of a 'β specific' BK channel opener, SR-5-130 were only partially restored in the patches containing BKαγ1-4 channels. Together this data highlights that subtle modifications in GoSlo-SR structures alter their effectiveness on BK channels with accessory γ subunits and this study

  11. Tx/Rx Head Coil Induces Less RF Transmit-Related Heating than Body Coil in Conductive Metallic Objects Outside the Active Area of the Head Coil

    PubMed Central

    Nagy, Zoltan; Oliver-Taylor, Aaron; Kuehne, Andre; Goluch, Sigrun; Weiskopf, Nikolaus

    2017-01-01

    The transmit–receive (Tx/Rx) birdcage head coil is often used for excitation instead of the body coil because of the presumably lower risk of heating in and around conductive implants. However, this common practice has not been systematically tested. To investigate whether the Tx/Rx birdcage head coil produces less heating than the body coil when scanning individuals with implants, we used a 3T clinical scanner and made temperature measurements around a straight 15 cm conductor using either the Tx/Rx body or the head coil for excitation. Additionally, the transmitted fields of a Tx/Rx head coil were measured both in air and in gel using a resonant and a non-resonant B field probes as well as a non-resonant E field probe. Simulations using a finite-difference time domain solver were compared with the experimental findings. When the body coil was used for excitation, we observed heating around the 15 cm wire at various anatomical locations (both within and outside of the active volume of the head coil). Outside its active area, no such heating was observed while using the Tx/Rx head coil for excitation. The E and B fields of the Tx/Rx birdcage head coil extended well-beyond the physical dimensions of the coil. In air, the fields were monotonically decreasing, while in gel they were more complex with local maxima at the end of the ASTM phantom. These experimental findings were line with the simulations. While caution must always be exercised when scanning individuals with metallic implants, these findings support the use of the Tx/Rx birdcage head coil in place of the body coil at 3T in order to reduce the risk of heating in and around conductive implants that are remote from the head coil. PMID:28184184

  12. Tx/Rx Head Coil Induces Less RF Transmit-Related Heating than Body Coil in Conductive Metallic Objects Outside the Active Area of the Head Coil.

    PubMed

    Nagy, Zoltan; Oliver-Taylor, Aaron; Kuehne, Andre; Goluch, Sigrun; Weiskopf, Nikolaus

    2017-01-01

    The transmit-receive (Tx/Rx) birdcage head coil is often used for excitation instead of the body coil because of the presumably lower risk of heating in and around conductive implants. However, this common practice has not been systematically tested. To investigate whether the Tx/Rx birdcage head coil produces less heating than the body coil when scanning individuals with implants, we used a 3T clinical scanner and made temperature measurements around a straight 15 cm conductor using either the Tx/Rx body or the head coil for excitation. Additionally, the transmitted fields of a Tx/Rx head coil were measured both in air and in gel using a resonant and a non-resonant B field probes as well as a non-resonant E field probe. Simulations using a finite-difference time domain solver were compared with the experimental findings. When the body coil was used for excitation, we observed heating around the 15 cm wire at various anatomical locations (both within and outside of the active volume of the head coil). Outside its active area, no such heating was observed while using the Tx/Rx head coil for excitation. The E and B fields of the Tx/Rx birdcage head coil extended well-beyond the physical dimensions of the coil. In air, the fields were monotonically decreasing, while in gel they were more complex with local maxima at the end of the ASTM phantom. These experimental findings were line with the simulations. While caution must always be exercised when scanning individuals with metallic implants, these findings support the use of the Tx/Rx birdcage head coil in place of the body coil at 3T in order to reduce the risk of heating in and around conductive implants that are remote from the head coil.

  13. Modulation of Kv3.4 channel N-type inactivation by protein kinase C shapes the action potential in dorsal root ganglion neurons.

    PubMed

    Ritter, David M; Ho, Cojen; O'Leary, Michael E; Covarrubias, Manuel

    2012-01-01

    Fast inactivation of heterologously expressed Kv3.4 channels is dramatically slowed upon phosphorylation of the channel's N-terminal (N-type) inactivation gate by protein kinase C (PKC). However, the presence and physiological importance of this exquisite modulation in excitable tissues were unknown. Here, we employed minimally invasive cell-attached patch-clamping, single-cell qPCR and specific siRNAs to unambiguously demonstrate that fast-inactivating Kv3.4 channels underlie a robust high voltage-activated A-type K(+) current (I(AHV)) in nociceptive dorsal root ganglion neurons from 7-day-old rats. We also show that PKC activation with phorbol 12,13-dibutyrate (PDBu) causes a 4-fold slowing of Kv3.4 channel inactivation and, consequently, accelerates the repolarization of the action potential (AP) by 22%, which shortens the AP duration by 14%. G-protein coupled receptor (GPCR) agonists eliminate I(AHV) fast inactivation in a membrane-delimited manner, suggesting a Kv3.4 channel signalling complex. Preincubation of the neurons with the PKC inhibitor bisindolylmaleimide II inhibits the effect of GPCR agonists and PDBu. Furthermore, activation of PKC via GPCR agonists recapitulates the effects of PDBu on the AP. Finally, transfection of the neurons with Kv3.4 siRNA prolongs the AP by 25% and abolishes the GPCR agonist-induced acceleration of the AP repolarization. These results show that Kv3.4 channels help shape the repolarization of the nociceptor AP, and that modulation of Kv3.4 channel N-type inactivation by PKC regulates AP repolarization and duration. We propose that the dramatic modulation of I(AHV) fast inactivation by PKC represents a novel mechanism of neural plasticity with potentially significant implications in the transition from acute to chronic pain.

  14. High-field superconducting nested coil magnet

    NASA Technical Reports Server (NTRS)

    Laverick, C.; Lobell, G. M.

    1970-01-01

    Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

  15. Pumpdown assistance extends coiled tubing reach

    SciTech Connect

    Tailby, R.J. )

    1992-07-01

    One of the most challenging coiled tubing applications to emerge in the last few years is horizontal well maintenance. When wireline cannot be used, techniques that offer some of the same flexibility, availability and relatively low cost must be used. During this same period, however, drilling technology has also made huge strides in horizontal and extended-reach areas. Wells are now being drilled with horizontal lengths in excess of 6,000 ft and measured depths of more than 22,000 ft. This paper reports that although horizontal wells are definitely here to stay, many operators have had to reevaluate their positions after being confronted with the problem of recompleting these wells to eliminate excessive water or gas production. A full workover with workstring using either a drilling rig or snubbing unit can be expensive and may lead to lost production because of limited rig availability. Coiled tubing has successfully been used in most cases thus far, but it has length and horizontal reach limitations that drilling technology will soon overtake. Within the constraints of current technology and tube capabilities, coiled tubing does not have the buckling resistance or reel capacity to service today's longest horizontal and extended reach wells or those planned and foreseen in the future. Even if coiled tubing can reach TD, operations requiring downward force are severely restricted.

  16. How loads affect coiled tubing life

    SciTech Connect

    Walker, E.J. Inc., AK )

    1992-01-01

    Fatigue testing was performed on 1-3/4-in OD, 0.125 in. wall thickness (WT) coiled tubing using a standard coiled tubing unit (CTU) as shown in this paper. Testing was conducted under Prudhoe Bay, Alaska oil well, conditions to determine the effects of axial load, internal pressure and bending stress on the longevity, or usable running footage, that can be expected with larger diameter tubing. The CTU was rigged up in a standard configuration with injector head 50 ft off the ground, the worst case for bending on most currently available North Slope units. Internal pressure was supplied by a small triplex pump and the end of tubing was closed off with a fishing neck and bull plug. Weight, for the first four tests, was suspended from the coiled tubing by a special clamp. The tubing was cycled up and over the guide arch until a loss of internal coiled tubing pressure (CTP) occurred, or until the tubing became stuck in the stripper brass.

  17. Stellarator Coil Design and Plasma Sensitivity

    SciTech Connect

    Long-Poe Ku and Allen H. Boozer

    2010-11-03

    The rich information contained in the plasma response to external magnetic perturbations can be used to help design stellarator coils more effectively. We demonstrate the feasibility by first devel- oping a simple, direct method to study perturbations in stellarators that do not break stellarator symmetry and periodicity. The method applies a small perturbation to the plasma boundary and evaluates the resulting perturbed free-boundary equilibrium to build up a sensitivity matrix for the important physics attributes of the underlying configuration. Using this sensitivity information, design methods for better stellarator coils are then developed. The procedure and a proof-of-principle application are given that (1) determine the spatial distributions of external normal magnetic field at the location of the unperturbed plasma boundary to which the plasma properties are most sen- sitive, (2) determine the distributions of external normal magnetic field that can be produced most efficiently by distant coils, (3) choose the ratios of the magnitudes of the the efficiently produced magnetic distributions so the sensitive plasma properties can be controlled. Using these methods, sets of modular coils are found for the National Compact Stellarator Experiment (NCSX) that are either smoother or can be located much farther from the plasma boundary than those of the present design.

  18. Simplified deflection-coil linearity testing

    NASA Technical Reports Server (NTRS)

    Kramer, G. P.

    1976-01-01

    Mask placed over face of image-dissecting photomultiplier tube has precision array of pinholes that permit light to impinge on tube at known points. Signals are fed to deflection coil which sweeps beam across each point without complex operator procedures.

  19. Sextupole correction coils for SSC model dipoles

    SciTech Connect

    Rechen, J.B.; Gilbert, W.S.; Hassenzahl, W.V.

    1985-05-01

    Local correction of the sextupole error field is proposed for the dipoles of the SSC. This requirement is imposed on the design by the high field quality required both during injection at low fields and during colliding beam operation at high fields. Error fields in the main dipole windings due to superconductor magnetization and conductor misplacements and unwanted sextupole and decapole magnetic field terms. To correct the sextupole error field we have constructed sextupole coils made of a single layer of superconducting wire and have mounted them with high precision on the stainless steel bore tube. These correction coils have been operated with 1 meter long SSC model dipoles in both the self-powered and externally-powered modes. The sextupole field in the bore has been reduced by as much as a factor of 50. The level of correction depends strongly on the angular alignment of the correction coil with respect to the sextupole error field it is to correct. Results of tests, performance of the correction coils and alignment requirements for the system are presented.

  20. Transcatheter Coil Embolization of Splenic Artery Aneurysm

    SciTech Connect

    Yamamoto, Satoshi Hirota, Shozo; Maeda, Hiroaki; Achiwa, Sachiko Arai, Keisuke; Kobayashi, Kaoru; Nakao, Norio

    2008-05-15

    The purpose of this study was to evaluate clinical results and technical problems of transcatheter coil embolization for splenic artery aneurysm. Subjects were 16 patients (8 men, 8 women; age range, 40-80 years) who underwent transcatheter embolization for splenic artery aneurysm (14 true aneurysms, 2 false aneurysms) at one of our hospitals during the period January 1997 through July 2005. Two aneurysms (12.5%) were diagnosed at the time of rupture. Multiple splenic aneurysms were found in seven patients. Aneurysms were classified by site as proximal (or strictly ostial) (n = 3), middle (n = 3), or hilar (n = 10). The indication for transcatheter arterial embolization was a false or true aneurysm 20 mm in diameter. Embolic materials were fibered coils and interlocking detachable coils. Embolization was performed by the isolation technique, the packing technique, or both. Technically, all aneurysms were devascularized without severe complications. Embolized aneurysms were 6-40 mm in diameter (mean, 25 mm). Overall, the primary technical success rate was 88% (14 of 16 patients). In the remaining 2 patients (12.5%), partial recanalization occurred, and re-embolization was performed. The secondary technical success rate was 100%. Seven (44%) of the 16 study patients suffered partial splenic infarction. Intrasplenic branching originating from the aneurysm was observed in five patients. We conclude that transcatheter coil embolization should be the initial treatment of choice for splenic artery aneurysm.

  1. Detail of heating coil for Machine Shop (Bldg. 163) ventilation ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of heating coil for Machine Shop (Bldg. 163) ventilation system Note portion of fan visible behind coil - Atchison, Topeka, Santa Fe Railroad, Albuquerque Shops, Machine Shop, 908 Second Street, Southwest, Albuquerque, Bernalillo County, NM

  2. Impact of the use of an endorectal coil for 3 T prostate MRI on image quality and cancer detection rate

    PubMed Central

    Gawlitza, Josephin; Reiss-Zimmermann, Martin; Thörmer, Gregor; Schaudinn, Alexander; Linder, Nicolas; Garnov, Nikita; Horn, Lars-Christian; Minh, Do Hoang; Ganzer, Roman; Stolzenburg, Jens-Uwe; Kahn, Thomas; Moche, Michael; Busse, Harald

    2017-01-01

    This work aims to assess the impact of an additional endorectal coil on image quality and cancer detection rate within the same patients. At a single academic medical center, this transversal study included 41 men who underwent T2- and diffusion-weighted imaging at 3 T using surface coils only or in combination with an endorectal coil in the same session. Two blinded readers (A and B) randomly evaluated all image data in separate sessions. Image quality with respect to localization and staging was rated on a five-point scale. Lesions were classified according to their prostate imaging reporting and data system (PIRADS) score version 1. Standard of reference was provided by whole-mount step-section analysis. Mean image quality scores averaged over all localization-related items were significantly higher with additional endorectal coil for both readers (p < 0.001), corresponding staging-related items were only higher for reader B (p < 0.001). With an endorectal coil, the rate of correctly detecting cancer per patient was significantly higher for reader B (p < 0.001) but not for reader A (p = 0.219). The numbers of histologically confirmed tumor lesions were rather similar for both settings. The subjectively rated 3-T image quality was improved with an endorectal coil. In terms of diagnostic performance, the use of an additional endorectal coil was not superior. PMID:28145525

  3. Impact of the use of an endorectal coil for 3 T prostate MRI on image quality and cancer detection rate

    NASA Astrophysics Data System (ADS)

    Gawlitza, Josephin; Reiss-Zimmermann, Martin; Thörmer, Gregor; Schaudinn, Alexander; Linder, Nicolas; Garnov, Nikita; Horn, Lars-Christian; Minh, Do Hoang; Ganzer, Roman; Stolzenburg, Jens-Uwe; Kahn, Thomas; Moche, Michael; Busse, Harald

    2017-02-01

    This work aims to assess the impact of an additional endorectal coil on image quality and cancer detection rate within the same patients. At a single academic medical center, this transversal study included 41 men who underwent T2- and diffusion-weighted imaging at 3 T using surface coils only or in combination with an endorectal coil in the same session. Two blinded readers (A and B) randomly evaluated all image data in separate sessions. Image quality with respect to localization and staging was rated on a five-point scale. Lesions were classified according to their prostate imaging reporting and data system (PIRADS) score version 1. Standard of reference was provided by whole-mount step-section analysis. Mean image quality scores averaged over all localization-related items were significantly higher with additional endorectal coil for both readers (p < 0.001), corresponding staging-related items were only higher for reader B (p < 0.001). With an endorectal coil, the rate of correctly detecting cancer per patient was significantly higher for reader B (p < 0.001) but not for reader A (p = 0.219). The numbers of histologically confirmed tumor lesions were rather similar for both settings. The subjectively rated 3-T image quality was improved with an endorectal coil. In terms of diagnostic performance, the use of an additional endorectal coil was not superior.

  4. Differential volume regulation and calcium signaling in two ciliary body cell types is subserved by TRPV4 channels

    PubMed Central

    Jo, Andrew O.; Lakk, Monika; Frye, Amber M.; Phuong, Tam T. T.; Redmon, Sarah N.; Roberts, Robin; Berkowitz, Bruce A.; Yarishkin, Oleg; Križaj, David

    2016-01-01

    Fluid secretion by the ciliary body plays a critical and irreplaceable function in vertebrate vision by providing nutritive support to the cornea and lens, and by maintaining intraocular pressure. Here, we identify TRPV4 (transient receptor potential vanilloid isoform 4) channels as key osmosensors in nonpigmented epithelial (NPE) cells of the mouse ciliary body. Hypotonic swelling and the selective agonist GSK1016790A (EC50 ∼33 nM) induced sustained transmembrane cation currents and cytosolic [Ca2+]i elevations in dissociated and intact NPE cells. Swelling had no effect on [Ca2+]i levels in pigment epithelial (PE) cells, whereas depolarization evoked [Ca2+]i elevations in both NPE and PE cells. Swelling-evoked [Ca2+]i signals were inhibited by the TRPV4 antagonist HC067047 (IC50 ∼0.9 μM) and were absent in Trpv4−/− NPE. In NPE, but not PE, swelling-induced [Ca2+]i signals required phospholipase A2 activation. TRPV4 localization to NPE was confirmed with immunolocalization and excitation mapping approaches, whereas in vivo MRI analysis confirmed TRPV4-mediated signals in the intact mouse ciliary body. Trpv2 and Trpv4 were the most abundant vanilloid transcripts in CB. Overall, our results support a model whereby TRPV4 differentially regulates cell volume, lipid, and calcium signals in NPE and PE cell types and therefore represents a potential target for antiglaucoma medications. PMID:27006502

  5. PRL-3 promotes the proliferation of LoVo cells via the upregulation of KCNN4 channels.

    PubMed

    Lai, Wei; Chen, Shuang; Wu, Heng; Guan, Yufeng; Liu, Lu; Zeng, Yujie; Zhao, Haiyan; Jiang, Jianmin; Chu, Zhonghua

    2011-10-01

    Previous studies have shown that phosphatase of regenerating liver-3 (PRL-3) plays an important role in the metastasis and proliferation of tumor cells. However, the mechanism by which PRL-3 controls the cell cycle of tumor cells remains unknown. In the present study, considering that the K+ channels strictly control cell proliferation, we examined whether K+ channels participate in the proliferation of tumor cells induced by PRL-3. Interestingly, the expression of intermediate-conductance Ca2+-activated K+ channels (KCNN4) was upregulated in an NF-κB-dependent manner when PRL-3 was transfected into LoVo cells. Also, we identified two NF-κB binding sites in the promoter region of KCNN4. Use of the specific inhibitor 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34) significantly inhibited the proliferation induced by PRL-3 and blocked the cell cycle at the G2/M phase. Meanwhile, the level of phosphorylation of Cdc2 was increased in a dose-dependent manner. Furthermore, TRAM-34 also inhibited tumor formation of PRL-3 cell xenografts implanted by injection in nude mice. In conclusion, PRL-3 promoted the proliferation of LoVo cells through upregulation of KCNN4 channels which facilitated the G2/M transition.

  6. Distinct Ca2+ sources in dendritic spines of hippocampal CA1 neurons couple to SK and Kv4 channels

    PubMed Central

    Wang, Kang; Lin, Mike T.; Adelman, John P.; Maylie, James

    2013-01-01

    SUMMARY Ca2+-activated SK channels and voltage-gated A-type Kv4 channels shape dendritic excitatory postsynaptic potentials (EPSPs) in hippocampal CA1 pyramidal neurons. Synaptically evoked Ca2+ influx through N-methyl-D-aspartate receptors (NMDARs) activates spine SK channels, reducing EPSPs and the associated spine head Ca2+ transient. However, results using glutamate uncaging implicated Ca2+ influx through SNX-482 (SNX) sensitive Cav2.3 (R-type) Ca2+ channels as the Ca2+ source for SK channel activation. The present findings show that using Schaffer collateral stimulation the effects of SNX and apamin are not mutually exclusive and SNX increases EPSPs independent of SK channel activity. Dialysis with 1,2-bis(o-aminophenoxy)ethane-N’N’N’-tetraacetic acid (BAPTA), application of 4-Aminopyridine (4-AP), expression of a Kv4.2 dominant negative subunit, and dialysis with a KChIPs antibody occluded the SNX-induced increase of EPSPs. The results suggest two distinct Ca2+ signaling pathways within dendritic spines, that links Ca2+ influx through NMDARs to SK channels and Ca2+ influx through R-type Ca2+ channels to Kv4.2-containing channels. PMID:24462100

  7. Coiled-Coil Irregularities and Instabilities in Group A Streptococcus M1 Are Required for Virulence

    SciTech Connect

    McNamara, Case; Zinkernagel, Annelies S.; Macheboeuf, Pauline; Cunningham, Madeleine W.; Nizet, Victor; Ghosh, Partho

    2008-07-21

    Antigenically variable M proteins are major virulence factors and immunogens of the human pathogen group A Streptococcus (GAS). Here, we report the -3 angstrom resolution structure of a GAS M1 fragment containing the regions responsible for eliciting type-specific, protective immunity and for binding fibrinogen, which promotes M1 proinflammatory and antiphagocytic functions. The structure revealed substantial irregularities and instabilities throughout the coiled coil of the M1 fragment. Similar structural irregularities occur in myosin and tropomyosin, explaining the patterns of cross-reactivity seen in autoimmune sequelae of GAS infection. Sequence idealization of a large segment of the M1 coiled coil enhanced stability but diminished fibrinogen binding, proinflammatory effects, and antibody cross-reactivity, whereas it left protective immunogenicity undiminished. Idealized M proteins appear to have promise as vaccine immunogens.

  8. Multiple-Coil, Pulse-Induction Metal Detector

    NASA Technical Reports Server (NTRS)

    Lesky, Edward S.; Reid, Alan M.; Bushong, Wilton E.; Dickey, Duane P.

    1988-01-01

    Multiple-head, pulse-induction metal detector scans area of 72 feet squared with combination of eight detector heads, each 3 ft. square. Head includes large primary coil inducing current in smaller secondary coils. Array of eight heads enables searcher to cover large area quickly. Pulses applied to primary coil, induced in secondary coils measured to determine whether metal present within range of detector head. Detector designed for recovery of Space Shuttle debris.

  9. GBNV encoded movement protein (NSm) remodels ER network via C-terminal coiled coil domain

    SciTech Connect

    Singh, Pratibha; Savithri, H.S.

    2015-08-15

    Plant viruses exploit the host machinery for targeting the viral genome–movement protein complex to plasmodesmata (PD). The mechanism by which the non-structural protein m (NSm) of Groundnut bud necrosis virus (GBNV) is targeted to PD was investigated using Agrobacterium mediated transient expression of NSm and its fusion proteins in Nicotiana benthamiana. GFP:NSm formed punctuate structures that colocalized with mCherry:plasmodesmata localized protein 1a (PDLP 1a) confirming that GBNV NSm localizes to PD. Unlike in other movement proteins, the C-terminal coiled coil domain of GBNV NSm was shown to be involved in the localization of NSm to PD, as deletion of this domain resulted in the cytoplasmic localization of NSm. Treatment with Brefeldin A demonstrated the role of ER in targeting GFP NSm to PD. Furthermore, mCherry:NSm co-localized with ER–GFP (endoplasmic reticulum targeting peptide (HDEL peptide fused with GFP). Co-expression of NSm with ER–GFP showed that the ER-network was transformed into vesicles indicating that NSm interacts with ER and remodels it. Mutations in the conserved hydrophobic region of NSm (residues 130–138) did not abolish the formation of vesicles. Additionally, the conserved prolines at positions 140 and 142 were found to be essential for targeting the vesicles to the cell membrane. Further, systematic deletion of amino acid residues from N- and C-terminus demonstrated that N-terminal 203 amino acids are dispensable for the vesicle formation. On the other hand, the C-terminal coiled coil domain when expressed alone could also form vesicles. These results suggest that GBNV NSm remodels the ER network by forming vesicles via its interaction through the C-terminal coiled coil domain. Interestingly, NSm interacts with NP in vitro and coexpression of these two proteins in planta resulted in the relocalization of NP to PD and this relocalization was abolished when the N-terminal unfolded region of NSm was deleted. Thus, the NSm

  10. ECH Plasma Experiments on an Internal Coil Device with a High Temperature Superconductor Coil

    SciTech Connect

    Ogawa, Yuichi; Morikawa, Junji; Ohkuni, Kotaro; Yamakoshi, Shigeo; Goto, Takuya; Mito, Toshiyuki; Yanagi, Nagato; Iwakuma, Masataka

    2005-01-15

    Self-organization related with relaxation phenomenon is playing an important role in various aspects of magnetic confined plasmas. Recently a relaxation theory including the plasma flow has been developed by Mahajan-Yoshida, and a new relaxation state has been identified. The two-fluid relaxation condition is given by {beta} + (V/V{sub A}){sup 2} = const. To study a self-organized structure with strong plasma flow, we have introduced an internal coil device. By inducing a radial electric field with appropriate methods, we could drive a toroidal plasma flow, and confine a high beta plasma in a core region. The internal coil device Mini-RT with a high temperature superconductor(HTS) coil(Rc=0.15m, Ic=50kA) has been constructed. The vacuum chamber is 1 m in diameter and {approx}0.7 m in height. The magnetic field strength near the internal coil is around 0.1 T, and a radio-frequency wave of 2.45 GHz is applied for the plasma production. We have started ECH plasma experiments with the coil supported mechanically. The electron density, which has a peak near the internal coil, is of order 10{sup 16} m{sup -3}, reaching the cut-off density of the microwave. While, the electron temperature is of order 10 eV with a broad profile. Estimated energy confinement time is of order 10{sup -(5-6)} sec. The levitation experiment of the HTS coil has been carried out. The position of the HTS coil is measured with laser sensors, and is feedback-controlled with the levitation coil current. We have succeeded to levitating the HTS coil during one hour with an accuracy of less than 20 {omega}m. A preliminary experiment for the plasma production at the floating condition of the HTS coil has been initiated. It is affirmed that the levitation system works well and plasma with separatrix configuration is produced.

  11. Compressing DNA sequence databases with coil

    PubMed Central

    White, W Timothy J; Hendy, Michael D

    2008-01-01

    Background Publicly available DNA sequence databases such as GenBank are large, and are growing at an exponential rate. The sheer volume of data being dealt with presents serious storage and data communications problems. Currently, sequence data is usually kept in large "flat files," which are then compressed using standard Lempel-Ziv (gzip) compression – an approach which rarely achieves good compression ratios. While much research has been done on compressing individual DNA sequences, surprisingly little has focused on the compression of entire databases of such sequences. In this study we introduce the sequence database compression software coil. Results We have designed and implemented a portable software package, coil, for compressing and decompressing DNA sequence databases based on the idea of edit-tree coding. coil is geared towards achieving high compression ratios at the expense of execution time and memory usage during compression – the compression time represents a "one-off investment" whose cost is quickly amortised if the resulting compressed file is transmitted many times. Decompression requires little memory and is extremely fast. We demonstrate a 5% improvement in compression ratio over state-of-the-art general-purpose compression tools for a large GenBank database file containing Expressed Sequence Tag (EST) data. Finally, coil can efficiently encode incremental additions to a sequence database. Conclusion coil presents a compelling alternative to conventional compression of flat files for the storage and distribution of DNA sequence databases having a narrow distribution of sequence lengths, such as EST data. Increasing compression levels for databases having a wide distribution of sequence lengths is a direction for future work. PMID:18489794

  12. Data-Driven Prediction and Design of bZIP Coiled-Coil Interactions

    PubMed Central

    Potapov, Vladimir; Kaplan, Jenifer B.; Keating, Amy E.

    2015-01-01

    Selective dimerization of the basic-region leucine-zipper (bZIP) transcription factors presents a vivid example of how a high degree of interaction specificity can be achieved within a family of structurally similar proteins. The coiled-coil motif that mediates homo- or hetero-dimerization of the bZIP proteins has been intensively studied, and a variety of methods have been proposed to predict these interactions from sequence data. In this work, we used a large quantitative set of 4,549 bZIP coiled-coil interactions to develop a predictive model that exploits knowledge of structurally conserved residue-residue interactions in the coiled-coil motif. Our model, which expresses interaction energies as a sum of interpretable residue-pair and triplet terms, achieves a correlation with experimental binding free energies of R = 0.68 and significantly out-performs other scoring functions. To use our model in protein design applications, we devised a strategy in which synthetic peptides are built by assembling 7-residue native-protein heptad modules into new combinations. An integer linear program was used to find the optimal combination of heptads to bind selectively to a target human bZIP coiled coil, but not to target paralogs. Using this approach, we designed peptides to interact with the bZIP domains from human JUN, XBP1, ATF4 and ATF5. Testing more than 132 candidate protein complexes using a fluorescence resonance energy transfer assay confirmed the formation of tight and selective heterodimers between the designed peptides and their targets. This approach can be used to make inhibitors of native proteins, or to develop novel peptides for applications in synthetic biology or nanotechnology. PMID:25695764

  13. Coiled-coil coactivators play a structural role mediating interactions in hypoxia-inducible factor heterodimerization.

    PubMed

    Guo, Yirui; Scheuermann, Thomas H; Partch, Carrie L; Tomchick, Diana R; Gardner, Kevin H

    2015-03-20

    The hypoxia-inducible factor complex (HIF-α·aryl hydrocarbon receptor nuclear translocator (ARNT)) requires association with several transcription coactivators for a successful cellular response to hypoxic stress. In addition to the conventional global transcription coactivator CREB-binding protein/p300 (CBP/p300) that binds to the HIF-α transactivation domain, a new group of transcription coactivators called the coiled-coil coactivators (CCCs) interact directly with the second PER-ARNT-SIM (PAS) domain of ARNT (ARNT PAS-B). These less studied transcription coactivators play essential roles in the HIF-dependent hypoxia response, and CCC misregulation is associated with several forms of cancer. To better understand CCC protein recruitment by the heterodimeric HIF transcription factor, we used x-ray crystallography, NMR spectroscopy, and biochemical methods to investigate the structure of the ARNT PAS-B domain in complex with the C-terminal fragment of a coiled-coil coactivator protein, transforming acidic coiled-coil coactivator 3 (TACC3). We found that the HIF-2α PAS-B domain also directly interacts with TACC3, motivating an NMR data-derived model suggesting a means by which TACC3 could form a ternary complex with HIF-2α PAS-B and ARNT PAS-B via β-sheet/coiled-coil interactions. These findings suggest that TACC3 could be recruited as a bridge to cooperatively mediate between the HIF-2α PAS-B·ARNT PAS-B complex, thereby participating more directly in HIF-dependent gene transcription than previously anticipated.

  14. Coiled-coil Coactivators Play a Structural Role Mediating Interactions in Hypoxia-inducible Factor Heterodimerization*

    PubMed Central

    Guo, Yirui; Scheuermann, Thomas H.; Partch, Carrie L.; Tomchick, Diana R.; Gardner, Kevin H.

    2015-01-01

    The hypoxia-inducible factor complex (HIF-α·aryl hydrocarbon receptor nuclear translocator (ARNT)) requires association with several transcription coactivators for a successful cellular response to hypoxic stress. In addition to the conventional global transcription coactivator CREB-binding protein/p300 (CBP/p300) that binds to the HIF-α transactivation domain, a new group of transcription coactivators called the coiled-coil coactivators (CCCs) interact directly with the second PER-ARNT-SIM (PAS) domain of ARNT (ARNT PAS-B). These less studied transcription coactivators play essential roles in the HIF-dependent hypoxia response, and CCC misregulation is associated with several forms of cancer. To better understand CCC protein recruitment by the heterodimeric HIF transcription factor, we used x-ray crystallography, NMR spectroscopy, and biochemical methods to investigate the structure of the ARNT PAS-B domain in complex with the C-terminal fragment of a coiled-coil coactivator protein, transforming acidic coiled-coil coactivator 3 (TACC3). We found that the HIF-2α PAS-B domain also directly interacts with TACC3, motivating an NMR data-derived model suggesting a means by which TACC3 could form a ternary complex with HIF-2α PAS-B and ARNT PAS-B via β-sheet/coiled-coil interactions. These findings suggest that TACC3 could be recruited as a bridge to cooperatively mediate between the HIF-2α PAS-B·ARNT PAS-B complex, thereby participating more directly in HIF-dependent gene transcription than previously anticipated. PMID:25627682

  15. High-sensitivity cooled coil system for nuclear magnetic resonance in kHz range

    SciTech Connect

    Lin, Tingting; Zhao, Jing; Zhang, Yi; Krause, Hans-Joachim; Lee, Yong-Ho; Lin, Jun

    2014-11-15

    In several low-field Nuclear Magnetic Resonance (LF-NMR) and surface nuclear magnetic resonance applications, i.e., in the frequency range of kHz, high sensitivity magnetic field detectors are needed. Usually, low-T{sub c} superconducting quantum interference devices (SQUIDs) with a high field sensitivity of about 1 fT/Hz{sup 1/2} are employed as detectors. Considering the flux trapping and operational difficulties associated with low-T{sub c} SQUIDs, we designed and fabricated liquid-nitrogen-cooled Cu coils for NMR detection in the kHz range. A cooled coil system consisting of a 9-cm diameter Cu coil and a low noise preamplifier was systematically investigated and reached a sensitivity of 2 fT/Hz{sup 1/2} at 77 K, which is 3 times better compared to the sensitivity at 300 K. A Q-switch circuit as an essential element for damping the ringing effects of the pickup coil was developed to acquire free induction decay signals of a water sample with minimum loss of signal. Our studies demonstrate that cooled Cu coils, if designed properly, can provide a comparable sensitivity to low-T{sub c} SQUIDs.

  16. High-Resolution Microscopy-Coil MR Imaging of Skin Tumors: Techniques and Novel Clinical Applications.

    PubMed

    Budak, Matthew J; Weir-McCall, Jonathan R; Yeap, Phey M; White, Richard D; Waugh, Shelley A; Sudarshan, Thiru A P; Zealley, Ian A

    2015-01-01

    High-resolution magnetic resonance (MR) imaging performed with a microscopy coil is a robust radiologic tool for the evaluation of skin lesions. Microscopy-coil MR imaging uses a small surface coil and a 1.5-T or higher MR imaging system. Simple T1- and T2-weighted imaging protocols can be implemented to yield high-quality, high-spatial-resolution images that provide an excellent depiction of dermal anatomy. The primary application of microscopy-coil MR imaging is to delineate the deep margins of skin tumors, thereby providing a preoperative road map for dermatologic surgeons. This information is particularly useful for surgeons who perform Mohs micrographic surgery and in cases of nasofacial neoplasms, where the underlying anatomy is complex. Basal cell carcinoma is the most common nonmelanocytic skin tumor and has a predilection to manifest on the face, where it can be challenging to achieve complete surgical excision while preserving the cosmetic dignity of the patient. Microscopy-coil MR imaging provides dermatologic surgeons with valuable preoperative anatomic information that is not available at conventional clinical examination.

  17. Idiopathic acquired generalized anhidrosis due to occlusion of proximal coiled ducts.

    PubMed

    Ogino, J; Saga, K; Kagaya, M; Kamada, A; Kaneko, R; Jimbow, K

    2004-03-01

    Idiopathic acquired generalized anhidrosis is a very rare disease of unknown pathogenesis. We report a 25-year-old man with acquired generalized anhidrosis due to occlusion of the coiled ducts. He did not have sweat secretion over the entire surface of the body, including the palms and soles. Sweat-inducing stimuli provoked tingling pain on the skin. Pilocarpine iontophoresis on the forearm did not induce sweat secretion. Neurological examination did not reveal any abnormality in the central or peripheral nervous system. Skin biopsy showed that the coiled ducts were occluded by an amorphous eosinophilic substance. This amorphous eosinophilic substance was positive with periodic acid-Schiff (PAS) staining and was resistant to digestion by diastase. Electron microscopy demonstrated that the coiled ducts were completely occluded by an amorphous substance. The substance occluding the coiled ducts contained fibrous structures. These findings suggested that the acquired generalized anhidrosis in this patient was caused by occlusion of the coiled ducts by a PAS-positive substance probably derived from dark cell granules.

  18. RWM control studies on RFX-mod with a limited set of active coils

    NASA Astrophysics Data System (ADS)

    Baruzzo, M.; Bolzonella, T.; Liu, Y. Q.; Manduchi, G.; Marchiori, G.; Soppelsa, A.; Takechi, M.; Villone, F.

    2012-10-01

    In this paper, the results of resistive wall mode (RWM) control experiments using several sets of active coils are presented. The control effectiveness as a function of coil number and covered torus surface is studied in the RFX-mod device, thanks to the powerful and flexible MHD active control system. Active control is tried using similar coil number and size both in the reversed field pinch (RFP) and in the tokamak configurations, giving a good experimental set to exploit the differences between the two cases. The experimental results are compared with predictions by a new integrated simulator for closed loop RWM growth. The numerical tool couples, in a self-consistent way, a full 3D finite element description of the machine boundaries, a 2D toroidal model of RFP plasma stability and a model of the RFX-mod control system, producing an overall dynamic model cast in the state variable space. In this way a full dynamic flight simulator of RWM control experiments is implemented, where coil coverage and experimental proportional-integral-derivative gains are explored in simulations. Both in the performed experiments and in simulations wall mode active control is proven to be possible in both the configurations with a very reduced set of active control coils. .

  19. Ecological succession of the microbial communities of an air-conditioning cooling coil in the tropics.

    PubMed

    Acerbi, E; Chénard, C; Miller, D; Gaultier, N E; Heinle, C E; Chang, V W-C; Uchida, A; Drautz-Moses, D I; Schuster, S C; Lauro, F M

    2017-03-01

    Air-conditioning systems harbor microorganisms, potentially spreading them to indoor environments. While air and surfaces in air-conditioning systems are periodically sampled as potential sources of indoor microbes, little is known about the dynamics of cooling coil-associated communities and their effect on the downstream airflow. Here, we conducted a 4-week time series sampling to characterize the succession of an air-conditioning duct and cooling coil after cleaning. Using an universal primer pair targeting hypervariable regions of the 16S/18S ribosomal RNA, we observed a community succession for the condensed water, with the most abundant airborne taxon Agaricomycetes fungi dominating the initial phase and Sphingomonas bacteria becoming the most prevalent taxa toward the end of the experiment. Duplicate air samples collected upstream and downstream of the coil suggest that the system does not act as ecological filter or source/sink for specific microbial taxa during the duration of the experiment.

  20. Simultaneous acquisition of spatial harmonics (SMASH): fast imaging with radiofrequency coil arrays.

    PubMed

    Sodickson, D K; Manning, W J

    1997-10-01

    SiMultaneous Acquisition of Spatial Harmonics (SMASH) is a new fast-imaging technique that increases MR image acquisition speed by an integer factor over existing fast-imaging methods, without significant sacrifices in spatial resolution or signal-to-noise ratio. Image acquisition time is reduced by exploiting spatial information inherent in the geometry of a surface coil array to substitute for some of the phase encoding usually produced by magnetic field gradients. This allows for partially parallel image acquisitions using many of the existing fast-imaging sequences. Unlike the data combination algorithms of prior proposals for parallel imaging, SMASH reconstruction involves a small set of MR signal combinations prior to Fourier transformation, which can be advantageous for artifact handling and practical implementation. A twofold savings in image acquisition time is demonstrated here using commercial phased array coils on two different MR-imaging systems. Larger time savings factors can be expected for appropriate coil designs.

  1. Embolization of Large Aneurysms with Long Wire Coils

    SciTech Connect

    Golzarian, Jafar; Dussaussois, Luc; Ait Said, Kamel; Abada, Hicham T.; Dereume, Jean P.; Struyven, Julien

    2002-01-15

    The authors report the experience of using long coils of 2 m length in the management of large aneurysms. Knowledge of the characteristics of these coils is of value for correct placement. These coils are safe and cost-effective for excluding large aneurysms.

  2. Embolization of large aneurysms with long wire coils.

    PubMed

    Golzarian, Jafar; Dussaussois, Luc; Ait Said, Kamel; Abada, Hicham T; Dereume, Jean P; Struyven, Julien

    2002-01-01

    The authors report the experience of using long coils of 2 m length in the management of large aneurysms. Knowledge of the characteristics of these coils is of value for correct placement. These coils are safe and cost-effective for excluding large aneurysms.

  3. Open coil structure for bubble-memory-device packaging

    NASA Technical Reports Server (NTRS)

    Chen, T. T.; Ypma, J. E.

    1975-01-01

    Concept has several important advantages over close-wound system: memory and coil chips are separate and interchangeable; interconnections in coil level are eliminated by packing memory chip and electronics in single structure; and coil size can be adjusted to optimum value in terms of power dissipation and field uniformity.

  4. New Retrievable Coil Anchors: Preliminary In Vivo Experiences in Swine

    SciTech Connect

    Konya, A. Wright, K.C.

    2005-04-15

    Purpose. To design and test retrievable coil anchors to improve the safety and efficacy of coil embolization. Methods. Fifty-two 0.038-inch homemade retrievable stainless steel coils were equipped with one of four different pre-shaped nitinol anchors and tested in 38 pigs. All coils with the anchor were completely retrieved and redeployed 3-18 times (median 7 times) prior to release. Types 1 and 2 anchored coils were acutely deployed in the external iliac arteries (n = 10 each), and chronically tested (1 week) in the common carotid arteries (n = 6 each). Larger type 1 (n = 4), type 3 (n = 6), and type 4 (n = 4) anchored coils were acutely deployed in the abdominal aorta. The largest type 1 anchors (n = 6) were acutely tested in the inferior vena cava. Results. All anchored coils were successfully retrieved and repositioned several times. All but two coils formed a compact plug and there was no coil migration except with two mechanically defective type 3 anchors. Conclusion. The use of retrievable anchors allowed the coils to be retrieved and repositioned, prevented coil migration, and enabled compact coil configuration.

  5. Modeling Endovascular MRI Coil Coupling with Transmit RF Excitation

    PubMed Central

    Venkateswaran, Madhav; Unal, Orhan; Hurley, Samuel; Samsonov, Alexey; Wang, Peng; Fain, Sean; Kurpad, Krishna

    2016-01-01

    Objective To model inductive coupling of endovascular coils with transmit RF excitation for selecting coils for MRI-guided interventions. Methods Independent and computationally efficient FEM models are developed for the endovascular coil, cable, transmit excitation and imaging domain. Electromagnetic and circuit solvers are coupled to simulate net B1+ fields and induced currents and voltages. Our models are validated using the Bloch Siegert B1+ mapping sequence for a series-tuned multimode coil, capable of tracking, wireless visualization and high resolution endovascular imaging. Results Validation shows good agreement at 24, 28 and 34 μT background RF excitation within experimental limitations. Quantitative coil performance metrics agree with simulation. A parametric study demonstrates trade off in coil performance metrics when varying number of coil turns. Tracking, imaging and wireless marker multimode coil features and their integration is demonstrated in a pig study. Conclusion Developed models for the multimode coil were successfully validated. Modeling for geometric optimization and coil selection serves as a precursor to time-consuming and expensive experiments. Specific applications demonstrated include parametric optimization, coil selection for a cardiac intervention and an animal imaging experiment. Significance Our modular, adaptable and computationally efficient modeling approach enables rapid comparison, selection and optimization of inductively-coupled coils for MRI-guided interventions. PMID:26960218

  6. Strong contributions from vertical triads to helix-partner preferences in parallel coiled coils.

    PubMed

    Steinkruger, Jay D; Bartlett, Gail J; Woolfson, Derek N; Gellman, Samuel H

    2012-09-26

    Pairing preferences in heterodimeric coiled coils are determined by complementarities among side chains that pack against one another at the helix-helix interface. However, relationships between dimer stability and interfacial residue identity are not fully understood. In the context of the "knobs-into-holes" (KIH) packing pattern, one can identify two classes of interactions between side chains from different helices: "lateral", in which a line connecting the adjacent side chains is perpendicular to the helix axes, and "vertical", in which the connecting line is parallel to the helix axes. We have previously analyzed vertical interactions in antiparallel coiled coils and found that one type of triad constellation (a'-a-a') exerts a strong effect on pairing preferences, while the other type of triad (d'-d-d') has relatively little impact on pairing tendencies. Here, we ask whether vertical interactions (d'-a-d') influence pairing in parallel coiled-coil dimers. Our results indicate that vertical interactions can exert a substantial impact on pairing specificity, and that the influence of the d'-a-d' triad depends on the lateral a' contact within the local KIH motif. Structure-informed bioinformatic analyses of protein sequences reveal trends consistent with the thermodynamic data derived from our experimental model system in suggesting that heterotriads involving Leu and Ile are preferred over homotriads involving Leu and Ile.

  7. Eight channel transmit array volume coil using on-coil radiofrequency current sources

    PubMed Central

    Kurpad, Krishna N.; Boskamp, Eddy B.

    2014-01-01

    Background At imaging frequencies associated with high-field MRI, the combined effects of increased load-coil interaction and shortened wavelength results in degradation of circular polarization and B1 field homogeneity in the imaging volume. Radio frequency (RF) shimming is known to mitigate the problem of B1 field inhomogeneity. Transmit arrays with well decoupled transmitting elements enable accurate B1 field pattern control using simple, non-iterative algorithms. Methods An eight channel transmit array was constructed. Each channel consisted of a transmitting element driven by a dedicated on-coil RF current source. The coil current distributions of characteristic transverse electromagnetic (TEM) coil resonant modes were non-iteratively set up on each transmitting element and 3T MRI images of a mineral oil phantom were obtained. Results B1 field patterns of several linear and quadrature TEM coil resonant modes that typically occur at different resonant frequencies were replicated at 128 MHz without having to retune the transmit array. The generated B1 field patterns agreed well with simulation in most cases. Conclusions Independent control of current amplitude and phase on each transmitting element was demonstrated. The transmit array with on-coil RF current sources enables B1 field shimming in a simple and predictable manner. PMID:24834418

  8. Manufacturing development of the Westinghouse Nb/sub 3/Sn coil for the Large Coil Test Program

    SciTech Connect

    Young, J.L.; Vota, T.L.; Singh, S.K.

    1983-01-01

    The Westinghouse Nb/sub 3/Sn Magnet for the Oak Ridge National Laboratory Large Coil Program (LCP) is currently well into the manufacturing phase. This paper identifies the manufacturing processes and development tasks for his unique, advanced coil.

  9. Evaluation method for in situ electric field in standardized human brain for different transcranial magnetic stimulation coils.

    PubMed

    Iwahashi, Masahiro; Gomez-Tames, Jose; Laakso, Ilkka; Hirata, Akimasa

    2017-03-21

    This study proposes a method to evaluate the electric field induced in the brain by transcranial magnetic stimulation (TMS) to realize focal stimulation in the target area considering the inter-subject difference of the brain anatomy. The TMS is a non-invasive technique used for treatment/diagnosis, and it works by inducing an electric field in a specific area of the brain via a coil-induced magnetic field. Recent studies that report on the electric field distribution in the brain induced by TMS coils have been limited to simplified human brain models or a small number of detailed human brain models. Until now, no method has been developed that appropriately evaluates the coil performance for a group of subjects. In this study, we first compare the magnetic field and the magnetic vector potential distributions to determine if they can be used as predictors of the TMS focality derived from the electric field distribution. Next, the hotspots of the electric field on the brain surface of ten subjects using six coils are compared. Further, decisive physical factors affecting the focality of the induced electric field by different coils are discussed by registering the computed electric field in a standard brain space for the first time, so as to evaluate coil characteristics for a large population of subjects. The computational results suggest that the induced electric field in the target area cannot be generalized without considering the morphological variability of the human brain. Moreover, there was no remarkable difference between the various coils, although focality could be improved to a certain extent by modifying the coil design (e.g., coil radius). Finally, the focality estimated by the electric field was more correlated with the magnetic vector potential than the magnetic field in a homogeneous sphere.

  10. Evaluation method for in situ electric field in standardized human brain for different transcranial magnetic stimulation coils

    NASA Astrophysics Data System (ADS)

    Iwahashi, Masahiro; Gomez-Tames, Jose; Laakso, Ilkka; Hirata, Akimasa

    2017-03-01

    This study proposes a method to evaluate the electric field induced in the brain by transcranial magnetic stimulation (TMS) to realize focal stimulation in the target area considering the inter-subject difference of the brain anatomy. The TMS is a non-invasive technique used for treatment/diagnosis, and it works by inducing an electric field in a specific area of the brain via a coil-induced magnetic field. Recent studies that report on the electric field distribution in the brain induced by TMS coils have been limited to simplified human brain models or a small number of detailed human brain models. Until now, no method has been developed that appropriately evaluates the coil performance for a group of subjects. In this study, we first compare the magnetic field and the magnetic vector potential distributions to determine if they can be used as predictors of the TMS focality derived from the electric field distribution. Next, the hotspots of the electric field on the brain surface of ten subjects using six coils are compared. Further, decisive physical factors affecting the focality of the induced electric field by different coils are discussed by registering the computed electric field in a standard brain space for the first time, so as to evaluate coil characteristics for a large population of subjects. The computational results suggest that the induced electric field in the target area cannot be generalized without considering the morphological variability of the human brain. Moreover, there was no remarkable difference between the various coils, although focality could be improved to a certain extent by modifying the coil design (e.g., coil radius). Finally, the focality estimated by the electric field was more correlated with the magnetic vector potential than the magnetic field in a homogeneous sphere.

  11. Electromagnetic fields in the human body due to switched transverse gradient coils in MRI.

    PubMed

    While, Peter T; Forbes, Larry K

    2004-07-07

    Magnetic resonance imaging scans impose large gradient magnetic fields on the patient. Modern imaging techniques require this magnetic field to be switched rapidly for good resolution. However, it is believed that this can also lead to the unwanted side effect of peripheral nerve stimulation, which proves to be a limiting factor to the advancement of MRI technology. This paper establishes an analytical model for the fields produced within an MRI scanner by transverse gradient coils of known current density. Expressions are obtained for the magnetic induction vector and the electric field vector, as well as for the surface charge and current densities that are induced on the patient's body. The expressions obtained are general enough to allow the study of any combination of gradient coils whose behaviour can be approximated by Fourier series. For a realistic example coil current density and switching function, it is found that spikes of surface charge density are induced on the patient's body as the gradient field is switched, as well as loops of surface current density that mimic the coil current density. For a 10 mT m(-1) gradient field with a rise time of 100 micros, the magnitude of the radial electric field at the body is found to be 10.3 V m(-1). It is also found that there is a finite limit to radial electric field strength as rise time approaches zero.

  12. CCBuilder: an interactive web-based tool for building, designing and assessing coiled-coil protein assemblies

    PubMed Central

    Wood, Christopher W.; Bruning, Marc; Ibarra, Amaurys Á.; Bartlett, Gail J.; Thomson, Andrew R.; Sessions, Richard B.; Brady, R Leo; Woolfson, Derek N.

    2014-01-01

    Motivation: The ability to accurately model protein structures at the atomistic level underpins efforts to understand protein folding, to engineer natural proteins predictably and to design proteins de novo. Homology-based methods are well established and produce impressive results. However, these are limited to structures presented by and resolved for natural proteins. Addressing this problem more widely and deriving truly ab initio models requires mathematical descriptions for protein folds; the means to decorate these with natural, engineered or de novo sequences; and methods to score the resulting models. Results: We present CCBuilder, a web-based application that tackles the problem for a defined but large class of protein structure, the α-helical coiled coils. CCBuilder generates coiled-coil backbones, builds side chains onto these frameworks and provides a range of metrics to measure the quality of the models. Its straightforward graphical user interface provides broad functionality that allows users to build and assess models, in which helix geometry, coiled-coil architecture and topology and protein sequence can be varied rapidly. We demonstrate the utility of CCBuilder by assembling models for 653 coiled-coil structures from the PDB, which cover >96% of the known coiled-coil types, and by generating models for rarer and de novo coiled-coil structures. Availability and implementation: CCBuilder is freely available, without registration, at http://coiledcoils.chm.bris.ac.uk/app/cc_builder/ Contact: D.N.Woolfson@bristol.ac.uk or Chris.Wood@bristol.ac.uk PMID:25064570

  13. Computational study for the effects of coil configuration on blood flow characteristics in coil-embolized cerebral aneurysm.

    PubMed

    Otani, Tomohiro; Ii, Satoshi; Shigematsu, Tomoyoshi; Fujinaka, Toshiyuki; Hirata, Masayuki; Ozaki, Tomohiko; Wada, Shigeo

    2016-07-21

    Coil embolization of cerebral aneurysms with inhomogeneous coil distribution leads to an incomplete occlusion of the aneurysm. However, the effects of this factor on the blood flow characteristics are still not fully understood. This study investigates the effects of coil configuration on the blood flow characteristics in a coil-embolized aneurysm using computational fluid dynamics (CFD) simulation. The blood flow analysis in the aneurysm with coil embolization was performed using a coil deployment (CD) model, in which the coil configuration was constructed using a physics-based simulation of the CD. In the CFD results, total flow momentum and kinetic energy in the aneurysm gradually decayed with increasing coil packing density (PD), regardless of the coil configuration attributed to deployment conditions. However, the total shear rate in the aneurysm was relatively high and the strength of the local shear flow varied based on the differences in coil configuration, even at adequate PDs used in clinical practice (20-25 %). Because the sufficient shear rate reduction is a well-known factor in the blood clot formation occluding the aneurysm inside, the present study gives useful insight into the effects of coil configuration on the treatment efficiency of coil embolization.

  14. All-atom simulations and free-energy calculations of coiled-coil peptides with lipid bilayers: binding strength, structural transition, and effect on lipid dynamics

    PubMed Central

    Woo, Sun Young; Lee, Hwankyu

    2016-01-01

    Peptides E and K, which are synthetic coiled-coil peptides for membrane fusion, were simulated with lipid bilayers composed of lipids and cholesterols at different ratios using all-atom models. We first calculated free energies of binding from umbrella sampling simulations, showing that both E and K peptides tend to adsorb onto the bilayer surface, which occurs more strongly in the bilayer composed of smaller lipid headgroups. Then, unrestrained simulations show that K peptides more deeply insert into the bilayer with partially retaining the helical structure, while E peptides less insert and predominantly become random coils, indicating the structural transition from helices to random coils, in quantitative agreement with experiments. This is because K peptides electrostatically interact with lipid phosphates, as well as because hydrocarbons of lysines of K peptide are longer than those of glutamic acids of E peptide and thus form stronger hydrophobic interactions with lipid tails. This deeper insertion of K peptide increases the bilayer dynamics and a vacancy below the peptide, leading to the rearrangement of smaller lipids. These findings help explain the experimentally observed or proposed differences in the insertion depth, binding strength, and structural transition of E and K peptides, and support the snorkeling effect. PMID:26926570

  15. All-atom simulations and free-energy calculations of coiled-coil peptides with lipid bilayers: binding strength, structural transition, and effect on lipid dynamics.

    PubMed

    Woo, Sun Young; Lee, Hwankyu

    2016-03-01

    Peptides E and K, which are synthetic coiled-coil peptides for membrane fusion, were simulated with lipid bilayers composed of lipids and cholesterols at different ratios using all-atom models. We first calculated free energies of binding from umbrella sampling simulations, showing that both E and K peptides tend to adsorb onto the bilayer surface, which occurs more strongly in the bilayer composed of smaller lipid headgroups. Then, unrestrained simulations show that K peptides more deeply insert into the bilayer with partially retaining the helical structure, while E peptides less insert and predominantly become random coils, indicating the structural transition from helices to random coils, in quantitative agreement with experiments. This is because K peptides electrostatically interact with lipid phosphates, as well as because hydrocarbons of lysines of K peptide are longer than those of glutamic acids of E peptide and thus form stronger hydrophobic interactions with lipid tails. This deeper insertion of K peptide increases the bilayer dynamics and a vacancy below the peptide, leading to the rearrangement of smaller lipids. These findings help explain the experimentally observed or proposed differences in the insertion depth, binding strength, and structural transition of E and K peptides, and support the snorkeling effect.

  16. All-atom simulations and free-energy calculations of coiled-coil peptides with lipid bilayers: binding strength, structural transition, and effect on lipid dynamics

    NASA Astrophysics Data System (ADS)

    Woo, Sun Young; Lee, Hwankyu

    2016-03-01

    Peptides E and K, which are synthetic coiled-coil peptides for membrane fusion, were simulated with lipid bilayers composed of lipids and cholesterols at different ratios using all-atom models. We first calculated free energies of binding from umbrella sampling simulations, showing that both E and K peptides tend to adsorb onto the bilayer surface, which occurs more strongly in the bilayer composed of smaller lipid headgroups. Then, unrestrained simulations show that K peptides more deeply insert into the bilayer with partially retaining the helical structure, while E peptides less insert and predominantly become random coils, indicating the structural transition from helices to random coils, in quantitative agreement with experiments. This is because K peptides electrostatically interact with lipid phosphates, as well as because hydrocarbons of lysines of K peptide are longer than those of glutamic acids of E peptide and thus form stronger hydrophobic interactions with lipid tails. This deeper insertion of K peptide increases the bilayer dynamics and a vacancy below the peptide, leading to the rearrangement of smaller lipids. These findings help explain the experimentally observed or proposed differences in the insertion depth, binding strength, and structural transition of E and K peptides, and support the snorkeling effect.

  17. Flat RF coils in static field gradient nuclear magnetic resonance.

    PubMed

    Stork, H; Gädke, A; Nestle, N; Fujara, F

    2009-10-01

    The use of flat RF coils allows considerable gains in the sensitivity of static field gradient (SFG) nuclear magnetic resonance (NMR) experiments. In this article, this effect is studied theoretically as well as experimentally. Additionally, the flat coil geometry has been studied theoretically depending on magnetic field gradient, pulse sequence and amplifier power. Moreover, detecting the signal directly from the free induction decay (FID) turned out to be quite attractive for STRAFI-like microimaging experiments, especially when using flat coils. In addition to wound rectangular flat coils also spiral flat coils have been developed which can be manufactured by photolithography from printed circuit boards.

  18. Change in the coil distribution of electrodynamic suspension system

    NASA Technical Reports Server (NTRS)

    Tanaka, Hisashi

    1992-01-01

    At the Miyazaki Maglev Test Center, the initial test runs were completed using a system design that required the superconducting coils to be parallel with the ground levitation coils. Recently, the coil distribution was changed to a system such that the two types of coils were perpendicular to each other. Further system changes will lead to the construction of a side wall levitation system. It is hoped that the development will culminate in a system whereby a superconducting coil will maintain all the functions: levitation, propulsion, and guidance.

  19. Superconducting coil system and methods of assembling the same

    DOEpatents

    Rajput-Ghoshal, Renuka; Rochford, James H.; Ghoshal, Probir K.

    2016-01-19

    A superconducting magnet apparatus is provided. The superconducting magnet apparatus includes a power source configured to generate a current; a first switch coupled in parallel to the power source; a second switch coupled in series to the power source; a coil coupled in parallel to the first switch and the second switch; and a passive quench protection device coupled to the coil and configured to by-pass the current around the coil and to decouple the coil from the power source when the coil experiences a quench.

  20. SSC (Superconducting Super Collider) dipole coil production tooling

    SciTech Connect

    Carson, J.A.; Barczak, E.J.; Bossert, R.C.; Brandt, J.S.; Smith, G.A.

    1989-03-01

    Superconducting Super Collider dipole coils must be produced to high precision to ensure uniform prestress and even conductor distribution within the collared coil assembly. Tooling is being prepared at Fermilab for the production of high precision 1M and 16.6M SSC dipole coils suitable for mass production. The design and construction methods builds on the Tevatron tooling and production experience. Details of the design and construction methods and measured coil uniformity of 1M coils will be presented. 4 refs., 10 figs.

  1. FIRST 100 T NON-DESTRUCTIVE MAGNET OUTER COIL SET

    SciTech Connect

    J. BACON; A. BACA; ET AL

    1999-09-01

    The controlled power outer coil set of the first 100 T non-destructive (100 T ND) magnet is described. This magnet will be installed as part of the user facility research equipment at the National High Magnetic Field laboratory (NHMFL) Pulsed Field Facility at Los Alamos National Laboratory. The 100 T ND controlled power outer coil set consists of seven nested, mechanically independent externally reinforced coils. These coils, in combination, will produce a 47 T platform field in a 225-mm diameter bore. Using inertial energy storage a synchronous motor/generator provides ac power to a set of seven ac-dc converters rated at 64 MW/80 MVA each. These converters energize three independent coil circuits to create 170 MJ of field energy in the outer coil set at the platform field of 47 T. Each coil consists of a multi-layer winding of high strength conductor supported by an external high strength stainless steel shell. Coils with the highest magnetic loads will utilize a reinforcing shell fabricated from highly cold worked 301 stainless steel strip. The autofrettage conditioning method will be used to pre-stress the coils and thereby limit conductor and reinforcement strains to the elastic range. The purpose of pre-stressing the coils is to attain a design life of 10,000 full field pulses. The operation and conditioning of the coil set will be described along with special features of its design, magnetic and structural analyses and construction.

  2. Study on cross section of high temperature superconducting coil

    NASA Astrophysics Data System (ADS)

    Ishiguri, Shinichi; Yamaguchi, Mitsugi; Fukui, Satoshi; Ogawa, Jun; Sato, Takao

    2007-01-01

    It is in particular of importance for HTS coils to secure a larger central magnetic field and/or a large stored energy with shorter length of HTS tapes. The critical current of an HTS tape depends on both the flux density and the flux angle against tapes. From this point, the performance improvement of HTS coils is taken into account with an analytical model. The minimum volume coil derived from the Fabry Factor constant curve is taken concerning the original coil shape, which is often employed in low temperature superconducting coils. The coil critical current was analyzed in consideration of the anisotropic properties of the tape. The electric field of HTS tapes in the coil was calculated at the coil critical current and the high electric field portion were cut out. The optimal coil cross section is obtained by iterating this calculation process. As a result, the critical current and the stored energy density of the coil were improved. The stored energy density increased about 17% and the central magnetic field was almost kept constant regardless of 19% reduction of HTS tapes, as compared with the original coil with the rectangular cross section.

  3. Elliptical Muon Helical Cooling Channel Coils

    SciTech Connect

    Kahn, S. A.; Flanagan, G.; Lopes, M. L.; Yonehara, K.

    2013-09-01

    A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoid, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional phase space reduction for muon beams. The most effective approach to implementing the desired magnetic field is a helical solenoid (HS) channel composed of short solenoid coils arranged in a helical pattern. The HS channel along with an external solenoid allows the B$_z$ and B$_{\\phi}$ components along the reference orbit to be set to any desired values. To set dB$_{\\phi}$/dr to the desired value for optimum focusing requires an additional variable to tune. We shall show that using elliptical shaped coils in the HS channel allows the flexibility to achieve the desired dB$_{\\phi}$/dr on the reference orbit without significant change to B$_z$ and B$_{\\phi}$.

  4. Magnetically Damped Furnace Bitter Magnet Coil 1

    NASA Technical Reports Server (NTRS)

    Bird, M. D.

    1997-01-01

    A magnet has been built by the National High Magnetic Field Laboratory for NASA on a cost reimbursement contract. The magnet is intended to demonstrate the technology and feasibility of building a magnet for space based crystal growth. A Bitter magnet (named after Francis Bitter, its inventor) was built consisting of four split coils electrically in series and hydraulically in parallel. The coils are housed in a steel vessel to reduce the fringe field and provide some on-axis field enhancement. The steel was nickel plated and Teflon coated to minimize interaction with the water cooling system. The magnet provides 0.14 T in a 184 mm bore with 3 kW of power.

  5. Common Coil Magnet System for VLHC

    SciTech Connect

    Gupta, R.

    1999-02-12

    This paper introduces the common coil magnet system for the proposed very large hadron collider (VLHC). In this system, the high energy booster (HEB), the injector to VLHC, is integrated as the iron dominated low field aperture within the coldmass of the common coil magnet design introduced earlier. This 4-in-1 magnet concept for a 2-in-1 machine should provide a major cost reduction in building and operating VLHC. Moreover, the proposed design reduces the field quality problems associated with the large persistent currents in Nb{sub 3}Sn magnets. The paper also shows that the geometric field harmonics can be made small. In this preliminary magnetic design. the current dependence in harmonics is significant but not umnanageable.

  6. Simulation calculation and characteristics analysis of coil motion noise

    NASA Astrophysics Data System (ADS)

    Meng, Yang; Peng, Cong; Fu, MingYe; Lu, Yiming; Yu, Zining; Zhu, Kaiguang

    2017-01-01

    Coil motion noise is one of the largest noises in airborne electromagnetic exploration, which results from the variations of magnetic flux in the Earth's magnetic accompanied by the receiver coil's movement during the flight. On the assumption of attitude measurements, coil motion noise is calculated according to roll, pitch and yaw of the receiver coils. Therefore, the characteristics of coil motion noise are analyzed in time domain, frequency domain and time-frequency domain. And the Gaussianity of coil motion noise is also discussed using the histogram of data and its estimated Gaussian function, and another method termed normal probability paper. All of these are to lay the foundation for removal of coil motion noise in airborne electromagnetic detection.

  7. Arrays of mutually coupled receiver coils: theory and application.

    PubMed

    Wright, S M; Magin, R L; Kelton, J R

    1991-01-01

    Specialized receiver coils having a small sensitive region can provide an improvement in SNR for MR imaging and spectroscopy, at the expense of limiting the usable field of view. This work presents a technique for designing coil arrays that allows the size and location of the sensitive region to be selected remotely. Only one element of the coil array is directly connected to the receiver, allowing flexibility in system design and implementation. A method is presented for the analysis and design of mutually coupled coil arrays of any number of elements of arbitrary shape. The analysis includes mutual coupling effects between primary coils, to allow multiple primary coils to be used simultaneously. A controller system allows remote selection of the sensitive region and automatically matches the impedance of the array to the preamplifier. Results obtained using a mutually coupled coil array designed for spine imaging are shown.

  8. Choice of coils for a fusion reactor

    PubMed Central

    Alexander, Romeo; Garabedian, Paul R.

    2007-01-01

    In a fusion reactor a hot plasma of deuterium and tritium is confined by a strong magnetic field to produce helium ions and release energetic neutrons. The 3D geometry of a stellarator provides configurations for such a device that reduce net toroidal current that might lead to disruptions. We construct smooth coils generating an external magnetic field designed to prevent the plasma from deteriorating. PMID:17640879

  9. Acute lung injury following refrigeration coil deicing.

    PubMed

    McKeown, Nathanael J; Burton, Brent T

    2012-03-01

    We report a case of a worker who developed ALI requiring mechanical ventilatory support after attempting to melt ice condensate by applying the flame of an oxy-acetylene torch to refrigeration coils charged with a halocarbon refrigerant in a closed environment. A discussion of possible etiologies are discussed, including phosgene, carbonyl fluoride, and nitrogen oxides. Primary prevention with adequate respiratory protection is recommended whenever deicing is performed in a closed space environment.

  10. A new moving-coil microelectrode puller.

    PubMed

    Ensor, D R

    1979-03-01

    This paper describes an improved electrode puller for the manufacture of glass microelectrodes or micropipettes. The instrument resembles a conventional horizontal two-stage, solenoid-powered electrode puller but the pull is now developed by a light moving-coil and a fixed permanent magnet, using the principle of the moving-coil loudspeaker. In a conventional puller the force is generated by a solenoid with a massive moving-iron core. In this new puller the moving-coil solenoid responds much more rapidly to changing currents because of its greatly reduced inductance, and a substantial reduction in mass to 25 g, gives more acceleration from a comparable force. The sudden discharge of a capacitor bank through the coil accelerates the glass quickly during the last stage of the pull. This rapid acceleration is of importance in the formation of good electrodes with fine tips. For the prototype, an electronic control unit was constructed which allows the parameters necessary for the manufacture of electrodes to be set and regulated accurately and repeatedly, so that series of electrodes of constant shapes can be made. The length of the electrode shank may be predetermined over a wide range and tip diameters down to 0.08 micron have already been measured. The angle of the taper that supports the tip may be varied from less than 1 to over 6 degrees. The mechanical design of the instrument is comparatively simple, as it has only one moving part, while the relative complexity of the electronic control section should not present any manufacturing difficulties. Although this puller has been used mainly to make single-barrel fine electrodes from borosilicate glass, it is adaptable for other purposes. The extent of the control over the shape of the shank of the electrode renders it particularly suitable for the manufacture of composite, ion-sensitive electrodes.

  11. Mechanical Resonances of Helically Coiled Carbon Nanowires

    PubMed Central

    Saini, D.; Behlow, H.; Podila, R.; Dickel, D.; Pillai, B.; Skove, M. J.; Serkiz, S. M.; Rao, A. M.

    2014-01-01

    Despite their wide spread applications, the mechanical behavior of helically coiled structures has evaded an accurate understanding at any length scale (nano to macro) mainly due to their geometrical complexity. The advent of helically coiled micro/nanoscale structures in nano-robotics, nano-inductors, and impact protection coatings has necessitated the development of new methodologies for determining their shear and tensile properties. Accordingly, we developed a synergistic protocol which (i) integrates analytical, numerical (i.e., finite element using COMSOL®) and experimental (harmonic detection of resonance; HDR) methods to obtain an empirically validated closed form expression for the shear modulus and resonance frequency of a singly clamped helically coiled carbon nanowire (HCNW), and (ii) circumvents the need for solving 12th order differential equations. From the experimental standpoint, a visual detection of resonances (using in situ scanning electron microscopy) combined with HDR revealed intriguing non-planar resonance modes at much lower driving forces relative to those needed for linear carbon nanotube cantilevers. Interestingly, despite the presence of mechanical and geometrical nonlinearities in the HCNW resonance behavior the ratio of the first two transverse modes f2/f1 was found to be similar to the ratio predicted by the Euler-Bernoulli theorem for linear cantilevers. PMID:24986377

  12. Carbon footprint of automotive ignition coil

    NASA Astrophysics Data System (ADS)

    Chang, Huey-Ling; Chen, Chih-Ming; Sun, Chin-Huang; Lin, Hung-Di

    2015-07-01

    In recent years, environmental issues, such as climate change and global warming due to the excessive development of industry, have attracted increasing attention of citizens worldwide. It is known that CO2 accounts for the largest proportion of greenhouse gases. Therefore, how to reduce CO2 emissions during the life cycle of a product to lessen its impact on environment is an important topic in the industrial society. Furthermore, it is also of great significance to cut down the required energy so as to lower its production costs during the manufacturing process nowadays. This study presents the carbon footprint of an automotive ignition coil and its partial materials are defined to explore their carbon emissions and environmental impact. The model IPCC GWP100a calculates potential global greenhouse effect by converting them into CO2 equivalents. In this way, the overall carbon footprint of an ignition coil can be explored. By using IPCC GWP100a, the results display that the shell has the most carbon emissions. The results can help the industry reduce the carbon emissions of an ignition coil product.

  13. Throttle coil operation of TMX-U

    SciTech Connect

    Correll, D.L.; Byers, J.A.; Casper, T.A.

    1983-01-01

    A tandem-mirror configuration with an axisymmetric central cell, similar to the geometry of MARS (Mirror Advanced Reactor Study) or the Kelley-TDF mode of MFTB-B, can be generated by inserting a 6-tesla, throttle coil in each end of the TMX-U central cell. The throttle coil geometry of TMX-U will test the physics issues associated with axisymmetric tandem-mirror reactors, such issues as: (1) increased radial confinement time for central-cell ions confined by axisymmetric mirror cells and electrostatic potentials; (2) theoretical limits set by the trapped particle instability for the required passing density between the central cell and the end-cell anchor; and (3) pumping of trapped particles within the thermal barrier and transition regions with methods other than neutral beams. The central-cell plasma parameters for the throttle coil geometry are evaluated for two operating points. The first requires heating hardware (neutral beams and ECRH) and vacuum performance at the TMX-U proposal level, yielding plasma parameters, central-cell betas, and plasma confinement exceeding those of the original TMX-U proposal. The second operating point, requiring approximately half the ECRH end-cell performance of the first, is predicted to equal the beta and to exceed the plasma pressure and confinement time of the central cell in the standard TMX-U geometry.

  14. Mechanical resonances of helically coiled carbon nanowires.

    PubMed

    Saini, D; Behlow, H; Podila, R; Dickel, D; Pillai, B; Skove, M J; Serkiz, S M; Rao, A M

    2014-07-02

    Despite their wide spread applications, the mechanical behavior of helically coiled structures has evaded an accurate understanding at any length scale (nano to macro) mainly due to their geometrical complexity. The advent of helically coiled micro/nanoscale structures in nano-robotics, nano-inductors, and impact protection coatings has necessitated the development of new methodologies for determining their shear and tensile properties. Accordingly, we developed a synergistic protocol which (i) integrates analytical, numerical (i.e., finite element using COMSOL) and experimental (harmonic detection of resonance; HDR) methods to obtain an empirically validated closed form expression for the shear modulus and resonance frequency of a singly clamped helically coiled carbon nanowire (HCNW), and (ii) circumvents the need for solving 12th order differential equations. From the experimental standpoint, a visual detection of resonances (using in situ scanning electron microscopy) combined with HDR revealed intriguing non-planar resonance modes at much lower driving forces relative to those needed for linear carbon nanotube cantilevers. Interestingly, despite the presence of mechanical and geometrical nonlinearities in the HCNW resonance behavior the ratio of the first two transverse modes f₂/f₁ was found to be similar to the ratio predicted by the Euler-Bernoulli theorem for linear cantilevers.

  15. Mechanical Resonances of Helically Coiled Carbon Nanowires

    NASA Astrophysics Data System (ADS)

    Saini, D.; Behlow, H.; Podila, R.; Dickel, D.; Pillai, B.; Skove, M. J.; Serkiz, S. M.; Rao, A. M.

    2014-07-01

    Despite their wide spread applications, the mechanical behavior of helically coiled structures has evaded an accurate understanding at any length scale (nano to macro) mainly due to their geometrical complexity. The advent of helically coiled micro/nanoscale structures in nano-robotics, nano-inductors, and impact protection coatings has necessitated the development of new methodologies for determining their shear and tensile properties. Accordingly, we developed a synergistic protocol which (i) integrates analytical, numerical (i.e., finite element using COMSOL®) and experimental (harmonic detection of resonance; HDR) methods to obtain an empirically validated closed form expression for the shear modulus and resonance frequency of a singly clamped helically coiled carbon nanowire (HCNW), and (ii) circumvents the need for solving 12th order differential equations. From the experimental standpoint, a visual detection of resonances (using in situ scanning electron microscopy) combined with HDR revealed intriguing non-planar resonance modes at much lower driving forces relative to those needed for linear carbon nanotube cantilevers. Interestingly, despite the presence of mechanical and geometrical nonlinearities in the HCNW resonance behavior the ratio of the first two transverse modes f2/f1 was found to be similar to the ratio predicted by the Euler-Bernoulli theorem for linear cantilevers.

  16. Single coil bistable, bidirectional micromechanical actuator

    DOEpatents

    Tabat, Ned; Guckel, Henry

    1998-09-15

    Micromechanical actuators capable of bidirectional and bistable operation can be formed on substrates using lithographic processing techniques. Bistable operation of the microactuator is obtained using a single coil and a magnetic core with a gap. A plunger having two magnetic heads is supported for back and forth linear movement with respect to the gap in the magnetic core, and is spring biased to a neutral position in which the two heads are on each side of the gap in the core. The single electrical coil is coupled to the core and is provided with electrical current to attract one of the heads toward the core by reluctance action to drive the plunger to a limit of travel in one direction. The current is then cut off and the plunger returns by spring action toward the gap, whereafter the current is reapplied to the coil to attract the other head of the plunger by reluctance action to drive the plunger to its other limit of travel. This process can be repeated at a time when switching of the actuator is required.

  17. Double tube helical coil steam generator

    SciTech Connect

    Garabedian, G.; De Luca, R.A.

    1987-02-24

    A steam generator is described comprising a container having a closed lower end, divided into longitudinally arranged sections including an uppermost disengaging chamber, an upper plenum, and a lower plenum. The upper plenum is above the lower plenum and contains a multiplicity of double tube helical coils, wherein each of the double tube helical coils is comprised of an inner tube individually enclosed for at least a portion of its length by an outer tube to form a double tube portion and thereby define an annular gap which is outside the inner tube but enclosed by the outer tube; the inner tube being attached at one end to a feedwater inlet, and the inner tube being attached at the other end to a steam outlet; the outer tube being in open communication at both ends with the disengaging chamber; the double tube portion being in the configuration of a helix for part of its length; the upper plenum having no communication with the disengaging chamber and having restricted communication with the lower plenum such that liquid metal entering the upper plenum and flowing to the lower plenum closely contacts at least a portion of the double tube helical coils; and the annular gap being at least partially filled with liquid metal.

  18. Coiling of elastic rods on rigid substrates

    PubMed Central

    Jawed, Mohammad K.; Da, Fang; Joo, Jungseock; Grinspun, Eitan; Reis, Pedro M.

    2014-01-01

    We investigate the deployment of a thin elastic rod onto a rigid substrate and study the resulting coiling patterns. In our approach, we combine precision model experiments, scaling analyses, and computer simulations toward developing predictive understanding of the coiling process. Both cases of deposition onto static and moving substrates are considered. We construct phase diagrams for the possible coiling patterns and characterize them as a function of the geometric and material properties of the rod, as well as the height and relative speeds of deployment. The modes selected and their characteristic length scales are found to arise from a complex interplay between gravitational, bending, and twisting energies of the rod, coupled to the geometric nonlinearities intrinsic to the large deformations. We give particular emphasis to the first sinusoidal mode of instability, which we find to be consistent with a Hopf bifurcation, and analyze the meandering wavelength and amplitude. Throughout, we systematically vary natural curvature of the rod as a control parameter, which has a qualitative and quantitative effect on the pattern formation, above a critical value that we determine. The universality conferred by the prominent role of geometry in the deformation modes of the rod suggests using the gained understanding as design guidelines, in the original applications that motivated the study. PMID:25267649

  19. Numerical dosimetry of transcranial magnetic stimulation coils

    NASA Astrophysics Data System (ADS)

    Crowther, Lawrence; Hadimani, Ravi; Jiles, David

    2014-03-01

    Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique capable of stimulating neurons by means of electromagnetic induction. TMS can be used to map brain function and shows promise for the diagnosis and treatment of neurological and psychiatric disorders. Calculation of fields induced in the brain are necessary to accurately identify stimulated neural tissue during TMS. This allows the development of novel TMS coil designs capable of stimulating deeper brain regions and increasing the localization of stimulation that can be achieved. We have performed numerical calculations of magnetic and electric field with high-resolution anatomically realistic human head models to find these stimulated brain regions for a variety of proposed TMS coil designs. The realistic head models contain heterogeneous tissue structures and electrical conductivities, yielding superior results to those obtained from the simplified homogeneous head models that are commonly employed. The attenuation of electric field as a function of depth in the brain and the localization of stimulating field have been methodically investigated. In addition to providing a quantitative comparison of different TMS coil designs the variation of induced field between subjects has been investigated. We also show the differences in induced fields between adult, adolescent and child head models to preemptively identify potential safety issues in the application of pediatric TMS.

  20. Theta Pinch Coil Design for SSX

    NASA Astrophysics Data System (ADS)

    Shrock, J. E.; Han, J.; Kaur, M.; Brown, M. R.; Schaffner, D. A.

    2016-10-01

    We present the essential physics and design parameters behind a theta pinch coil used on SSX. The coil is used as an accelerator to drive flux behind a Taylor plume traveling about 30 km/sec. Operating between 25 and 40 kV on a time scale < 10 μs , the design focuses on minimizing the quarter cycle rise time (π/2√{ LC }) of the coil while maintaining the necessary precautions for working at high voltage. Our design works with 1.1 and 3.3 μF capacitors and a maximum stored electrical energy of U =1/2 CV2 = 880 J (at the lower capacitance). This electrical energy is converted into kinetic energy in the plume. Each plume has a mass greater than 30 μg , giving an initial kinetic energy of at least 14 J . At perfect efficiency, the upper bound of the plume velocity will be 240 km/sec using the lower capacitance circuit. Work supported by DOE OFES and ARPA-E ALPHA programs.

  1. Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery

    PubMed Central

    Chittiboina, Prashant; Talagala, S. Lalith; Merkle, Hellmut; Sarlls, Joelle E.; Montgomery, Blake K.; Piazza, Martin G.; Scott, Gretchen; Ray-Chaudhury, Abhik; Lonser, Russell R.; Oldfield, Edward H.; Koretsky, Alan P.; Butman, John A.

    2016-01-01

    OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing’s disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra–high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm3 and 0.15 × 0.15 × 0.30 mm3, respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p < 0.01) in the SNR were inversely proportional to the distance from the ESC tip to the anterior pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented

  2. Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery.

    PubMed

    Chittiboina, Prashant; Lalith Talagala, S; Merkle, Hellmut; Sarlls, Joelle E; Montgomery, Blake K; Piazza, Martin G; Scott, Gretchen; Ray-Chaudhury, Abhik; Lonser, Russell R; Oldfield, Edward H; Koretsky, Alan P; Butman, John A

    2016-12-01

    OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing's disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra-high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm(3) and 0.15 × 0.15 × 0.30 mm(3), respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p < 0.01) in the SNR were inversely proportional to the distance from the ESC tip to the anterior pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented

  3. MR coil sensitivity inhomogeneity correction for plaque characterization in carotid arteries

    NASA Astrophysics Data System (ADS)

    Salvado, Olivier; Hillenbrand, Claudia; Suri, Jasjit; Wilson, David L.

    2004-05-01

    We are involved in a comprehensive program to characterize atherosclerotic disease using multiple MR images having different contrast mechanisms (T1W, T2W, PDW, magnetization transfer, etc.) of human carotid and animal model arteries. We use specially designed intravascular and surface array coils that give high signal-to-noise but suffer from sensitivity inhomogeneity. With carotid surface coils, challenges include: (1) a steep bias field with an 80% change; (2) presence of nearby muscular structures lacking high frequency information to distinguish bias from anatomical features; (3) many confounding zero-valued voxels subject to fat suppression, blood flow cancellation, or air, which are not subject to coil sensitivity; and (4) substantial noise. Bias was corrected using a modification of the adaptive fuzzy c-mean method reported by Pham et al. (IEEE TMI, 18:738-752), whereby a bias field modeled as a mechanical membrane was iteratively improved until cluster means no longer changed. Because our images were noisy, we added a noise reduction filtering step between iterations and used about 5 classes. In a digital phantom having a bias field measured from our MR system, variations across an area comparable to a carotid artery were reduced from 50% to <5% with processing. Human carotid images were qualitatively improved and large regions of skeletal muscle were relatively flat. Other commonly applied techniques failed to segment the images or introduced strong edge artifacts. Current evaluations include comparisons to bias as measured by a body coil in human MR images.

  4. Development of Radar Navigation and Radio Data Transmission for Microhole Coiled Tubing Bottom Hole Assemblies

    SciTech Connect

    Larry G. Stolarczyk; Gerald L. Stolarczyk; Larry Icerman; John Howard; Hooman Tehrani

    2007-03-25

    This Final Technical Report summarizes the research and development (R&D) work performed by Stolar Research Corporation (Stolar) under U.S. Department of Energy (DOE) Contract Number DE-FC26-04NT15477. This work involved the development of radar navigation and radio data transmission systems for integration with microhole coiled tubing bottom hole assemblies. Under this contract, Stolar designed, fabricated, and laboratory and field tested two advanced technologies of importance to the future growth of the U.S. oil and gas industry: (1) real-time measurement-while-drilling (MWD) for guidance and navigation of coiled tubing drilling in hydrocarbon reservoirs and (2) two-way inductive radio data transmission on coiled tubing for real-time, subsurface-to-surface data transmission. The operating specifications for these technologies are compatible with 3.5-inch boreholes drilled to a true vertical depth (TVD) of 5,000 feet, which is typical of coiled tubing drilling applications. These two technologies (i.e., the Stolar Data Transmission System and Drill String Radar) were developed into pre-commercial prototypes and tested successfully in simulated coiled tubing drilling conditions. Integration of these two technologies provides a real-time geosteering capability with extremely quick response times. Stolar is conducting additional work required to transition the Drill String Radar into a true commercial product. The results of this advanced development work should be an important step in the expanded commercialization of advanced coiled tubing microhole drilling equipment for use in U.S. hydrocarbon reservoirs.

  5. Theoretical design of gradient coils with minimum power dissipation: Accounting for the discretization of current density into coil windings

    NASA Astrophysics Data System (ADS)

    While, Peter T.; Korvink, Jan G.; Shah, N. Jon; Poole, Michael S.

    2013-10-01

    Gradient coil windings are typically constructed from either variable width copper tracks or fixed width wires. Excessive power dissipation within these windings during gradient coil operation limits the maximum drive current or duty cycle of the coil. It is common to design gradient coils in terms of a continuous minimum power current density and to perform a discretization to obtain the locations of the coil tracks or wires. However, the existence of finite gaps between these conductors and a maximum conductor width leads to an underestimation of coil resistance when calculated using the continuous current density. Put equivalently, the actual current density within the tracks or wires is higher than that used in the optimization and this departure results in suboptimal coil designs. In this work, a mapping to an effective current density is proposed to account for these effects and provide the correct contribution to the power dissipation. This enables the design of gradient coils that are genuinely optimal in terms of power minimization, post-discretization. The method was applied to the theoretical design of a variety of small x- and z-gradient coils for use in small animal imaging and coils for human head imaging. Computer-driven comparisons were made between coils designed with and without the current density mapping, in terms of simulated power dissipation. For coils to be built using variable width tracks, the method provides slight reductions in power dissipation in most cases and substantial gains only in cases where the minimum separation between track centre-lines is less than twice the gap size. However, for coils to be built using fixed width wires, very considerable reductions in dissipated power are consistently attainable (up to 60%) when compared to standard approaches of coil optimization.

  6. Protein-based hydrogels self-assembled from genetically engineered triblock polypeptides containing coiled-coil domains

    NASA Astrophysics Data System (ADS)

    Xu, Chunyu

    Protein-based biomaterials have great potential in biomedical applications due to their similar composition with biological organisms. Environment-sensitive hydrogels based on proteins can undergo sol-gel transition due to the conformational change of the proteins in response to external stimuli. The physical properties of these hydrogels can be tailored by modification of the protein structures. Two major hypotheses were made in this dissertation. One was that coiled-coil folding motifs could be a good candidate for physical crosslinking in protein-based hydrogels, and the other was that the conformational change of coiled-coils in response to external stimuli could mediate the sol-gel transition of the protein-based hydrogels. The first part established synthesis strategies of the coiled-coil containing proteins using a genetic engineering technique. An important observation was made that the fusion sequence on the proteins could influence the thermal stability of the proteins. In the second part of the research, the self-assembly of hydrogels from a series of triblock polypeptides containing coiled-coils was evaluated. It was found that the hydrogels had a porous interconnected network microstructure. The hydrogels responded to temperature and pH, which correlated to the temperature- and pH-triggered structural transition of the coiled-coil domains. In addition, the formation of hydrogels was reversible in the present or absence of guanidine hydrochloride (GdnHCl). The last part of the research attempted to explore the relationship between the structure of the protein polymers and the physical property of the hydrogels, and to investigate the parameters influencing the hydrogel formation and physical properties. Triblock and diblock polypeptides were designed to contain different lengths of coiled-coil domains. Tyrosine residues were incorporated at selected solvent-exposed positions in order to increase the hydrophobicity of the coiled-coil domains. The

  7. Ballistocardiogram of avian eggs determined by an electromagnetic induction coil.

    PubMed

    Ono, H; Akiyama, R; Sakamoto, Y; Pearson, J T; Tazawa, H

    1997-07-01

    As an avian embryo grows within an eggshell, the whole egg is moved by embryonic activity and also by the embryonic heartbeat. A technical interest in detecting minute biological movements has prompted the development of techniques and systems to measure the cardiogenic ballistic movement of the egg or ballistocardiogram (BCG). In this context, there is interest in using an electromagnetic induction coil (solenoid) as another simple sensor to measure the BCG and examining its possibility for BCG measurement. A small permanent magnet is attached tightly to the surface of an incubated egg, and then the egg with the magnet is placed in a solenoid. Preliminary model analysis is made to design a setup of the egg, magnet and solenoid coupling system. Then, simultaneous measurement with a laser displacement measuring system, developed previously, is made for chicken eggs, indicating that the solenoid detects the minute cardiogenic ballistic movements and that the BCG determined is a measure of the velocity of egg movements.

  8. Apparatus having inductively coupled coaxial coils for measuring buildup of slay or ash in a furnace

    DOEpatents

    Mathur, Mahendra P.; Ekmann, James M.

    1989-01-01

    The buildup of slag or ash on the interior surface of a furnace wall is monitored by disposing two coils to form a transformer which is secured adjacent to the inside surface of the furnace wall. The inductive coupling between the two coils of the transformer is affected by the presence of oxides of iron in the slag or ash which is adjacent to the transformer, and the application of a voltage to one winding produces a voltage at the other winding that is related to the thickness of the slag or ash buildup on the inside surface of the furnace wall. The output of the other winding is an electrical signal which can be used to control an alarm or the like or provide an indication of the thickness of the slag or ash buildup at a remote location.

  9. TEM transmission line coil with double nuclear capability.

    PubMed

    Erickson, Matthew G; Kurpad, Krishna N; Holmes, James H; Fain, Sean B

    2007-10-01

    MR imaging and spectroscopy requires RF fields of high homogeneity. Quadrature volume coils meeting this requirement include the birdcage coil and the TEM resonator. We describe here a quadrature volume coil designed around a modified coaxial transmission line in which multiple inner conductors are arrayed on a circular perimeter and surrounded by a common shield. Current antinodes are established at appropriate points on the inner conductors by series transmission line stubs, either open circuit or short circuit, which terminate the line. Quadrature phasing is generated by a novel circuit constructed from a pair of high-performance current baluns and a commercial quadrature hybrid. The coil is a "pure" TEM coil as it is simply a resonant transmission line. There is no mode structure to consider. The construction of a prototype quadrature four-element coil is described and preliminary test results from this coil in a 4.7T horizontal bore magnet are reported. A related double nuclear coil design for (3)He and (1)H in which two linear transmission line coils are arrayed on a circular perimeter and simultaneously tuned and matched to their respective frequencies is also described. Preliminary tests from this coil in a 1.5T clinical scanner are reported.

  10. Gas-phase IR spectra of intact [alpha]-helical coiled coil protein complexes

    NASA Astrophysics Data System (ADS)

    Pagel, Kevin; Kupser, Peter; Bierau, Frauke; Polfer, Nicolas C.; Steill, Jeffrey D.; Oomens, Jos; Meijer, Gerard; Koksch, Beate; von Helden, Gert

    2009-06-01

    Electrospray ionization (ESI) is the softest ionization method that is currently available and it is widely accepted, that ESI generated ions of proteins and protein assemblies at certain conditions retain characteristic aspects of their solution-state conformation. ESI mass spectrometry (MS) therefore evolved as a useful tool to obtain information on composition, stoichiometry, and dynamics of non-covalently associated protein complexes. While tertiary structure information of proteins can be obtained from ion mobility spectrometry (IMS), only a few techniques yield direct information on the secondary structure of gas-phase peptides and proteins. We present here the mid-IR spectroscopic secondary structural analysis of three de novo designed [alpha]-helical coiled coil model peptides and their non-covalently associated complexes in the gas-phase. The conformational stability of such coiled coil peptides in solution is primarily driven by aggregation. Isolated monomers usually remain unfolded. Two of the investigated peptides were designed to assemble into stable [alpha]-helical complexes in acidic solution, while the third one remains monomeric and unfolded at these conditions. Monomer ions of all three peptides show comparable photodissociation IR spectra and therefore suggest an unfolded conformation in the gas phase. In contrast, considerable CO stretch (amide-I) and N-H bend (amide-II) band shifts have been observed for the dimers which is consistent with an elevated H-bond content. These findings provide evidence that at least a fraction of the condensed phase [alpha]-helical structure is retained in the gas-phase coiled coil complexes.

  11. Physiologically-relevant measurements of flow through coils and stents: towards improved modeling of endovascular treatment of intracranial aneurysms

    NASA Astrophysics Data System (ADS)

    Barbour, Michael; Levitt, Michael; Geindreau, Christian; Rolland Du Roscoat, Sabine; Johnson, Luke; Chivukula, Keshav; Aliseda, Alberto

    2016-11-01

    The hemodynamic environment in cerebral aneurysms undergoing flow-diverting stent (FDS) or coil embolization treatment plays a critical role in long-term outcomes. Standard modeling approaches to endovascular coils and FDS simplify the complex geometry into a homogenous porous volume or surface through the addition of a Darcy-Brinkman pressure loss term in the momentum equation. The inertial and viscous loss coefficients are typically derived from published in vitro studies of pressure loss across FDS and coils placed in a straight tube, where the only fluid path is across the treatment - an unrealistic representation of treatment apposition in vivo. The pressure drop across FDS and coils in side branch aneurysms located on curved parent vessels is measured. Using PIV, the velocity at the aneurysm neck plane is reconstructed and used to determine loss coefficients for better models of endovascular coils or FDS that account for physiological placement and vessel curvature. These improved models are incorporated into CFD simulations and validated against in vitro model PIV velocity, as well as compared to microCT-based coil/stent-resolving CFD simulations of patient-specific treated aneurysm flow.

  12. Type I macrophage scavenger receptor contains α-helical and collagen-like coiled coils

    NASA Astrophysics Data System (ADS)

    Kodama, Tatsuhiko; Freeman, Mason; Rohrer, Lucia; Zabrecky, James; Matsudaira, Paul; Krieger, Monty

    1990-02-01

    The macrophage scavenger receptor is a trimeric membrane glycoprotein with unusual ligand-binding properties which has been implicated in the development of atherosclerosis. The trimeric structure of the bovine type I scavenger receptor, deduced by complementary DNA cloning, contains three extracellular C-terminal cysteine-rich domains connected to the transmembrane domain by a long fibrous stalk. This stalk structure, composed of an a-helical coiled coil and a collagen-like triple helix, has not previously been observed in an integral membrane protein.

  13. Three-coil inductively coupled plasma (ICP) source with individually controlled coil currents supplied from a single power generator

    NASA Astrophysics Data System (ADS)

    Dorf, Leonid; Rauf, Shahid; Liu, Jonathan; Kenney, Jason; Lane, Steven; Nguyen, Andrew; Ramaswamy, Kartik; Collins, Ken

    2013-09-01

    As requirements on plasma uniformity get more stringent in the semiconductor industry, an ICP source with 3 coils becomes warranted. Designing a power distribution/50 Ω-tuning network (PDN) that delivers the power from a single generator to 3 coils is complicated, due to inductive coupling between the coils, and between coils and plasma. Our PDN comprises several capacitors, including 2 variable ones, C1,2, connected in parallel to 2 coils. A set of equations for coils/plasma currents was solved over a wide parameter space to determine practical values/ranges for all capacitors. It was shown that by moving along a pre-determined programming path in C1,2 space, one can attain various coil current ratios (CCR) without crossing resonance curves. The latter causes coil current reversal, which may result in plasma instabilities and affect uniformity. Based on modeling results, the PDN was built and tested using a specially made 3-coil source. A wide range of CCR was achieved by varying C1,2, including maxima or minima in any 2 coils. With slight adjustments (to account for parasitics and actual plasma coupling), the model correctly predicted experimentally observed CCR for each tested C1,2 pair. Likewise, the theoretical resonance structure was reproduced experimentally with good agreement.

  14. X-Ray Crystal Structure of a TRPM Assembly Domain Reveals An Antiparallel Four-Stranded Coiled-Coil

    SciTech Connect

    Fujiwara, Y.; Minor, D.L.; Jr.

    2009-05-18

    Transient receptor potential (TRP) channels comprise a large family of tetrameric cation-selective ion channels that respond to diverse forms of sensory input. Earlier studies showed that members of the TRPM subclass possess a self-assembling tetrameric C-terminal cytoplasmic coiled-coil domain that underlies channel assembly and trafficking. Here, we present the high-resolution crystal structure of the coiled-coil domain of the channel enzyme TRPM7. The crystal structure, together with biochemical experiments, reveals an unexpected four-stranded antiparallel coiled-coil architecture that bears unique features relative to other antiparallel coiled-coils. Structural analysis indicates that a limited set of interactions encode assembly specificity determinants and uncovers a previously unnoticed segregation of TRPM assembly domains into two families that correspond with the phylogenetic divisions seen for the complete subunits. Together, the data provide a framework for understanding the mechanism of TRPM channel assembly and highlight the diversity of forms found in the coiled-coil fold.

  15. A procedure for refining a coiled coil protein structure using x-ray fiber diffraction and modeling.

    PubMed Central

    Briki, Fatma; Doucet, Jean; Etchebest, Catherine

    2002-01-01

    We describe a combined use of experimental and simulation techniques to configure side chains in a coiled coil structure. As already demonstrated in a previous work, x-ray diffraction patterns from hard alpha-keratin fibers in the 5.15 A meridian zone reflect the global configuration of the chi(1) dihedral angle of the coiled coil side chains. Molecular simulations, such as energy minimization and molecular dynamics, and rotameric representation in the PDB, are used here on a heterodimeric coiled coil to investigate the dihedral angle distribution along the sequence. Different procedures have been used to build the structure, the quality assessment was based on the agreement between the simulated diffraction patterns and the experimental ones in the fingerprint region of coiled coils (5.15 A). The best one for building a realistic coiled coil structure consists of placing the side chains using molecular dynamics (MD) simulations, followed by side chain positioning using SMD or SCWRL procedures. The side chains and the backbone are equilibrated during the MD until they reach an equilibrium state for the t/g(+) ratio. Positioning the side chains on the resulting backbone, using the above procedures, gives rise to a well-defined 5.15 A meridian reflection. PMID:12324400

  16. The heterotrimeric laminin coiled-coil domain exerts anti-adhesive effects and induces a pro-invasive phenotype.

    PubMed

    Santos-Valle, Patricia; Guijarro-Muñoz, Irene; Cuesta, Angel M; Alonso-Camino, Vanesa; Villate, Maider; Alvarez-Cienfuegos, Ana; Blanco, Francisco J; Sanz, Laura; Alvarez-Vallina, Luis

    2012-01-01

    Laminins are large heterotrimeric cross-shaped extracellular matrix glycoproteins with terminal globular domains and a coiled-coil region through which the three chains are assembled and covalently linked. Laminins are key components of basement membranes, and they serve as attachment sites for cell adhesion, migration and proliferation. In this work, we produced a recombinant fragment comprising the entire laminin coiled-coil of the α1-, β1-, and γ1-chains that assemble into a stable heterotrimeric coiled-coil structure independently of the rest of the molecule. This domain was biologically active and not only failed to serve as a substrate for cell attachment, spreading and focal adhesion formation but also inhibited cell adhesion to laminin when added to cells in a soluble form at the time of seeding. Furthermore, gene array expression profiling in cells cultured in the presence of the laminin coiled-coil domain revealed up-regulation of genes involved in cell motility and invasion. These findings were confirmed by real-time quantitative PCR and zymography assays. In conclusion, this study shows for the first time that the laminin coiled-coil domain displays anti-adhesive functions and has potential implications for cell migration during matrix remodeling.

  17. The Heterotrimeric Laminin Coiled-Coil Domain Exerts Anti-Adhesive Effects and Induces a Pro-Invasive Phenotype

    PubMed Central

    Santos-Valle, Patricia; Guijarro-Muñoz, Irene; Cuesta, Ángel M.; Alonso-Camino, Vanesa; Villate, Maider; Álvarez-Cienfuegos, Ana; Blanco, Francisco J.; Sanz, Laura; Álvarez-Vallina, Luis

    2012-01-01

    Laminins are large heterotrimeric cross-shaped extracellular matrix glycoproteins with terminal globular domains and a coiled-coil region through which the three chains are assembled and covalently linked. Laminins are key components of basement membranes, and they serve as attachment sites for cell adhesion, migration and proliferation. In this work, we produced a recombinant fragment comprising the entire laminin coiled-coil of the α1-, β1-, and γ1-chains that assemble into a stable heterotrimeric coiled-coil structure independently of the rest of the molecule. This domain was biologically active and not only failed to serve as a substrate for cell attachment, spreading and focal adhesion formation but also inhibited cell adhesion to laminin when added to cells in a soluble form at the time of seeding. Furthermore, gene array expression profiling in cells cultured in the presence of the laminin coiled-coil domain revealed up-regulation of genes involved in cell motility and invasion. These findings were confirmed by real-time quantitative PCR and zymography assays. In conclusion, this study shows for the first time that the laminin coiled-coil domain displays anti-adhesive functions and has potential implications for cell migration during matrix remodeling. PMID:22723936

  18. High-field magnetic resonance imaging using solenoid radiofrequency coils.

    PubMed

    Vegh, Viktor; Gläser, Philipp; Maillet, Donald; Cowin, Gary J; Reutens, David C

    2012-10-01

    High-resolution magnetic resonance imaging using dedicated high-field radiofrequency micro-coils at 16.4 T (700 MHz) was investigated. Specific solenoid coils primarily using silver and copper as conductors with enamel and polyurethane coatings were built to establish which coil configuration produces the best image. Image quality was quantified using signal-to-noise ratio and signal variation over regions of interest. Benchmarking was conducted using 5-mm diameter coils, as this size is comparable to an established coil of the same size. Our 1.4-mm-diameter coils were compared directly to each other, from which we deduce performance as a function of conductor material and coating. A variety of materials and conductor coatings allowed us to choose an optimal design, which we used to image a kidney section at 10-micron resolution. We applied zero-fill extrapolation to achieve 5-micron resolution.

  19. Chronic vascular reactions to steel coil occlusion devices.

    PubMed

    Barth, K H; Strandberg, J D; Kaufman, S L; White, R I

    1978-09-01

    Original Gianturco steel coil vascular embolization devices and two modifications were compared for their occlusive effects and for the degree of adverse reaction in the surrounding vessel wall. Modifications consisted of silk or Ivalon replacing the wool strands of the original device. Single coils were placed into the left renal artery of nine mixed breed swine and restudied 3 months later. The bare coils did not occlude the vessels nor lead to significant foreign body reaction. Wool, silk, and Ivalon coils produced prompt and sustained renal artery occlusion. Upon histologic examination of the vessel wall, foreign body and chronic inflammatory reaction was found to be strongest against wool. This reaction was less with silk and markedly diminished with Ivalon. The results indicate that silk and Ivalon coils, while having the same occlusive effect, are preferable to wool coils if less local reaction is desired.

  20. Performance verification tests of JT-60SA CS model coil

    NASA Astrophysics Data System (ADS)

    Obana, Tetsuhiro; Murakami, Haruyuki; Takahata, Kazuya; Hamaguchi, Shinji; Chikaraishi, Hirotaka; Mito, Toshiyuki; Imagawa, Shinsaku; Kizu, Kaname; Natsume, Kyohei; Yoshida, Kiyoshi

    2015-11-01

    As a final check of the coil manufacturing method of the JT-60 Super Advanced (JT-60SA) central solenoid (CS), we verified the performance of a CS model coil. The model coil comprised a quad-pancake wound with a Nb3Sn cable-in-conduit conductor. Measurements of the critical current, joint resistance, pressure drop, and magnetic field were conducted in the verification tests. In the critical-current measurement, the critical current of the model coil coincided with the estimation derived from a strain of -0.62% for the Nb3Sn strands. As a result, critical-current degradation caused by the coil manufacturing process was not observed. The results of the performance verification tests indicate that the model coil met the design requirements. Consequently, the manufacturing process of the JT-60SA CS was established.