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Sample records for 4-channel surface coils

  1. An Embedded 4-Channel Receive-Only RF Coil Array for fMRI Experiments of the Somatosensory Pathway in Conscious Awake Marmosets at 7T

    PubMed Central

    Papoti, Daniel; Yen, Cecil Chern-Chyi; Mackel, Julie B.; Merkle, Hellmut; Silva, Afonso C.

    2014-01-01

    Functional Magnetic Resonance Imaging (fMRI) has established itself as the main research tool in neuroscience and brain cognitive research. The common marmoset (Callithrix jacchus) is a non-human primate model of increasing interest in biomedical research. However, commercial MRI coils for marmosets are not generally available. The present work describes the design and construction of a 4-channel receive-only surface RF coil array with excellent signal-to-noise ratio (SNR) specifically optimized for fMRI experiments in awake marmosets in response to somatosensory stimulation. The array was designed as part of a helmet-based head restraint system used to prevent motion during the scans. High SNR was obtained by building the coil array using a thin and flexible substrate glued to the inner surface of the restraint helmet, so as to minimize the distance between the array elements and the somatosensory cortex. Decoupling between coil elements was achieved by partial geometrical overlapping and by connecting them to home-built low input impedance preamplifiers. In vivo images show excellent coverage of the brain cortical surface with high sensitivity near the somatosensory cortex. Embedding the coil elements within the restraint helmet allowed fMRI data in response to somatosensory stimulation to be collected with high sensitivity and reproducibility in conscious, awake marmosets. PMID:23696219

  2. A 4-channel coil array interconnection by analog direct modulation optical link for 1.5-T MRI.

    PubMed

    Yuan, Jing; Wei, Juan; Shen, Gary X

    2008-10-01

    Optical glass fiber shows great advantages over coaxial cables in terms of electromagnetic interference, thus, it should be considered a potential alternative for magnetic resonance imaging (MRI) receive coil interconnection, especially for a large number coil array at high field. In this paper, we propose a 4-channel analog direct modulation optical link for a 1.5-T MRI coil array interconnection. First, a general direct modulated optical link is compared to an external modulated optical link. And then the link performances of the proposed direct modulated optical link, including power gain, frequency response, and dynamic range, are analyzed and measured. Phantom and in vivo head images obtained using this optical link are demonstrated for comparison with those obtained by cable connections. The signal-to-noise (SNR) analysis shows that the optical link achieves 6%-8% SNR a improvement over coaxial cables by elimination of electrical interference between cables during MR signal transmission.

  3. 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).

  4. Optimized quadrature surface coil designs

    PubMed Central

    Kumar, Ananda; Bottomley, Paul A.

    2008-01-01

    Background Quadrature surface MRI/MRS detectors comprised of circular loop and figure-8 or butterfly-shaped coils offer improved signal-to-noise-ratios (SNR) compared to single surface coils, and reduced power and specific absorption rates (SAR) when used for MRI excitation. While the radius of the optimum loop coil for performing MRI at depth d in a sample is known, the optimum geometry for figure-8 and butterfly coils is not. Materials and methods The geometries of figure-8 and square butterfly detector coils that deliver the optimum SNR are determined numerically by the electromagnetic method of moments. Figure-8 and loop detectors are then combined to create SNR-optimized quadrature detectors whose theoretical and experimental SNR performance are compared with a novel quadrature detector comprised of a strip and a loop, and with two overlapped loops optimized for the same depth at 3 T. The quadrature detection efficiency and local SAR during transmission for the three quadrature configurations are analyzed and compared. Results The SNR-optimized figure-8 detector has loop radius r8 ∼ 0.6d, so r8/r0 ∼ 1.3 in an optimized quadrature detector at 3 T. The optimized butterfly coil has side length ∼ d and crossover angle of ≥ 150° at the center. Conclusions These new design rules for figure-8 and butterfly coils optimize their performance as linear and quadrature detectors. PMID:18057975

  5. 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.

  6. [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.

  7. 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.

  8. [Ultrafast MR sialography: comparison of two coil systems including an alternative surface coil].

    PubMed

    Weber, T F; Cramer, M C; Aldefeld, D; Weiss, F; Petersen, K U; Reitmeier, F; Jaehne, M; Adam, G; Habermann, C R

    2008-11-01

    To compare the visualization of salivary ducts by ultrafast magnetic resonance sialography (MR sialography) using an alternative surface coil and a conventional head-neck coil. In 11 healthy volunteers, ultrafast MR sialography (single shot turbo spin echo; acquisition time, 2.8 s) was performed before and after oral application of a sialogogue. Each subject received examinations with both a bilateral surface coil (SC) and a conventional head-neck coil (HNC). The depiction of parotideal and submandibular duct systems was graded from 1 to 5 (5 = poor) by four independent radiologists. ANOVA served for statistical analysis of duct rankings, and interobserver variability was determined by Intraclass Correlation Coefficient (ICC). With an excellent ICC of 0.96, both coil systems offered symmetric visualization of salivary ducts, and the image quality increased after oral application of sialogogue (p < 0.001). In total, the overall rating was worse for SC than for HNC (2.13 +/- 1.24 vs. 1.45 +/- 0.65, p < 0.001). SC was especially inferior in depiction of submandibular and extraglandular duct components compared to HNC (p < 0.001). Most notably due to the reduced visualization of extraglandular and submandibular ducts, the specific surface coil used in this study was inferior in image quality and does not constitute a reasonable alternative to conventional coil systems.

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

    DTIC Science & Technology

    2014-10-23

    resonant at the same frequency. Coils will be in a “quadrant surface layout” in which all coils are in a four square arrangement to measure mutual ...Coil Array, probe, Nuclear Magnetic Resonance, tuning, decoupling, RLC, mutual coupling, RLC I. INTRODUCTION N Nuclear quadrupole resonance (NQR...same tuning to the 28.578MHz resonant frequency. III. QUADRANT MUTUAL COUPLING Now that the probes are tuned individually, the focus is now on

  10. Effects of MR surface coils on PET quantification

    PubMed Central

    MacDonald, Lawrence R.; Kohlmyer, Steve; Liu, Chi; Lewellen, Thomas K.; Kinahan, Paul E.

    2011-01-01

    Purpose: The goal of this work was to investigate the effects of MRI surface coils on attenuation-corrected PET emission data. The authors studied the cases where either an MRI or a CT scan would be used to provide PET attenuation correction (AC). Combined MR∕PET scanners that use the MRI for PET AC (MR-AC) face the challenge of absent surface coils in MR images and thus cannot directly account for attenuation in the coils. Combining MR and PET images could be achieved by transporting the subject on a stereotactically registered table between independent MRI and PET scanners. In this case, conventional PET CT-AC methods could be used. A challenge here is that high atomic number materials within MR coils cause artifacts in CT images and CT based AC is typically not validated for coil materials. Methods: The authors evaluated PET artifacts when MR coils were absent from AC data (MR-AC), or when coil attenuation was measured by CT scanning (CT-AC). They scanned PET phantoms with MR surface coils on a clinical PET∕CT system and used CT-AC to reconstruct PET data. The authors then omitted the coil from the CT-AC image to mimic the MR-AC scenario. Images were acquired using cylinder and anthropomorphic phantoms. They evaluated and compared the following five scenarios: (1) A uniform cylinder phantom and head coil scanned and reconstructed using CT-AC; (2) similar emission data (with head coil present) were reconstructed without the head coil in the AC data; (3) the same cylinder scanned without the head coil present (reference scan); (4) a PET torso phantom with a full MR torso coil present in both PET and CT; (5) only half of the separable torso coil present in the PET∕CT acquisition. The authors also performed analytic simulations of the first three scenarios. Results: Streak artifacts were present in CT images containing MR surface coils due to metal components. These artifacts persisted after the CT images were converted for PET AC. The artifacts were

  11. Effects of MR surface coils on PET quantification.

    PubMed

    MacDonald, Lawrence R; Kohlmyer, Steve; Liu, Chi; Lewellen, Thomas K; Kinahan, Paul E

    2011-06-01

    The goal of this work was to investigate the effects of MRI surface coils on attenuation-corrected PET emission data. The authors studied the cases where either an MRI or a CT scan would be used to provide PET attenuation correction (AC). Combined MR/PET scanners that use the MRI for PET AC (MR-AC) face the challenge of absent surface coils in MR images and thus cannot directly account for attenuation in the coils. Combining MR and PET images could be achieved by transporting the subject on a stereotactically registered table between independent MRI and PET scanners. In this case, conventional PET CT-AC methods could be used. A challenge here is that high atomic number materials within MR coils cause artifacts in CT images and CT based AC is typically not validated for coil materials. The authors evaluated PET artifacts when MR coils were absent from AC data (MR-AC), or when coil attenuation was measured by CT scanning (CT-AC). They scanned PET phantoms with MR surface coils on a clinical PET/CT system and used CT-AC to reconstruct PET data. The authors then omitted the coil from the CT-AC image to mimic the MR-AC scenario. Images were acquired using cylinder and anthropomorphic phantoms. They evaluated and compared the following five scenarios: (1) A uniform cylinder phantom and head coil scanned and reconstructed using CT-AC; (2) similar emission data (with head coil present) were reconstructed without the head coil in the AC data; (3) the same cylinder scanned without the head coil present (reference scan); (4) a PET torso phantom with a full MR torso coil present in both PET and CT; (5) only half of the separable torso coil present in the PET/CT acquisition. The authors also performed analytic simulations of the first three scenarios. Streak artifacts were present in CT images containing MR surface coils due to metal components. These artifacts persisted after the CT images were converted for PET AC. The artifacts were significantly reduced when half of the

  12. 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.

  13. Surface-scanning coil detectors for magnetoelastic biosensors: A comparison of planar-spiral and solenoid coils

    NASA Astrophysics Data System (ADS)

    Chai, Yating; Horikawa, Shin; Wikle, Howard C.; Wang, Zhenyu; Chin, Bryan A.

    2013-10-01

    This research introduces a planar spiral coil as a surface-scanning detector for magnetoelastic biosensors, which have been used to detect bacteria directly on food surfaces. The planar coil was compared with the previously investigated solenoid coil, in terms of the magnetic flux change, signal amplitude, and detection distance. Both theoretical calculations and experimental results demonstrated that the planar coil detector yields a dramatically improved signal amplitude and greater detection distance. In addition, simultaneous measurement of multiple biosensors on surfaces was demonstrated. This planar coil is therefore anticipated to facilitate the detection of bacteria on surfaces using magnetoelastic biosensors.

  14. 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.

  15. Directed surface attachment of nanomaterials via coiled-coil-driven self-assembly

    PubMed Central

    Szymonik, Michal; Wardingley, Richard A; Pye, Douglas; Davies, A Giles; Wälti, Christoph; Stockley, Peter G

    2016-01-01

    Numerous nanoscale devices and materials have been fabricated in recent years using a variety of biological scaffolds. However, the interfacing of these devices and materials into existing circuits and ordered arrays has proved problematic. Here, we describe a simple solution to this problem using self-assembly of the peptide coiled-coil heterodimer ACID:BASE to immobilize M13 bacteriophage particles to specific locations on a patterned gold surface. Surface plasmon resonance demonstrated that free ACID peptides will assemble onto a surface derivatized with BASE. We then displayed the ACID peptide on the pIX coat protein of M13 and showed that these phage particles permit formation of the coiled-coil resulting in specific surface attachment. The ACID:immobilized BASE affinities appear to be similar for free peptide and phage-displayed ACID. Finally, we fabricated two gold electrodes, separated by a 200 nm gap, coated one of them with BASE and showed that this allows localization of the M13:ACID onto the functionalized electrode. PMID:23154792

  16. Directed surface attachment of nanomaterials via coiled-coil-driven self-assembly

    NASA Astrophysics Data System (ADS)

    White, Simon J.; Johnson, Steven; Szymonik, Michal; Wardingley, Richard A.; Pye, Douglas; Davies, A. Giles; Wälti, Christoph; Stockley, Peter G.

    2012-12-01

    Numerous nanoscale devices and materials have been fabricated in recent years using a variety of biological scaffolds. However, the interfacing of these devices and materials into existing circuits and ordered arrays has proved problematic. Here, we describe a simple solution to this problem using self-assembly of the peptide coiled-coil heterodimer ACID:BASE to immobilize M13 bacteriophage particles to specific locations on a patterned gold surface. Surface plasmon resonance demonstrated that free ACID peptides will assemble onto a surface derivatized with BASE. We then displayed the ACID peptide on the pIX coat protein of M13 and showed that these phage particles permit formation of the coiled-coil resulting in specific surface attachment. The ACID:immobilized BASE affinities appear to be similar for free peptide and phage-displayed ACID. Finally, we fabricated two gold electrodes, separated by a 200 nm gap, coated one of them with BASE and showed that this allows localization of the M13:ACID onto the functionalized electrode.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Inductance and resistance measurement method for vessel detection and coil powering in all-surface inductive heating systems composed of outer squircle coils

    NASA Astrophysics Data System (ADS)

    Kilic, Veli Tayfun; Unal, Emre; Demir, Hilmi Volkan

    2017-05-01

    In this work, we investigate a method proposed for vessel detection and coil powering in an all-surface inductive heating system composed of outer squircle coils. Besides conventional circular coils, coils with different shapes such as outer squircle coils are used for and enable efficient all-surface inductive heating. Validity of the method, which relies on measuring inductance and resistance values of a loaded coil at different frequencies, is experimentally demonstrated for a coil with shape different from conventional circular coil. Simple setup was constructed with a small coil to model an all-surface inductive heating system. Inductance and resistance maps were generated by measuring coil's inductance and resistance values at different frequencies loaded by a plate made of different materials and located at various positions. Results show that in an induction hob for various coil geometries it is possible to detect a vessel's presence, to identify its material type and to specify its position on the hob surface by considering inductance and resistance of the coil measured on at least two different frequencies. The studied method is important in terms of enabling safe, efficient and user flexible heating in an all-surface inductive heating system by automatically detecting the vessel's presence and powering on only the coils that are loaded by the vessel with predetermined current levels.

  4. 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.

  5. Design of a surface-scanning coil detector for direct bacteria detection on food surfaces using a magnetoelastic biosensor

    NASA Astrophysics Data System (ADS)

    Chai, Yating; Wikle, Howard C.; Wang, Zhenyu; Horikawa, Shin; Best, Steve; Cheng, Zhongyang; Dyer, Dave F.; Chin, Bryan A.

    2013-09-01

    The real-time, in-situ bacteria detection on food surfaces was achieved by using a magnetoelastic biosensor combined with a surface-scanning coil detector. This paper focuses on the coil design for signal optimization. The coil was used to excite the sensor's vibration and detect its resonant frequency signal. The vibrating sensor creates a magnetic flux change around the coil, which then produces a mutual inductance. In order to enhance the signal amplitude, a theory of the sensor's mutual inductance with the measurement coil is proposed. Both theoretical calculations and experimental data showed that the working length of the coil has a significant effect on the signal amplitude. For a 1 mm-long sensor, a coil with a working length of 1.3 mm showed the best signal amplitude. The real-time detection of Salmonella bacteria on a fresh food surface was demonstrated using this new technology.

  6. 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...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...resonant. Exactly 376pF of fixed capacitors were added to the coil in parallel until the coil matched closely to 50 ohms. The network analyzer was

  7. 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.

  8. 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

    Weinberger, Oliver; 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

    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. 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. 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. 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.

  9. Surface Coil Intensity Correction in Magnetic Resonance Imaging in Spinal Metastases.

    PubMed

    Ren, Hong; Lin, Wei; Ding, Xianjun

    2017-01-01

    To evaluate the clinical application of phased-array surface coil intensity correction in magnetic resonance imaging (MRI) in spinal metastases. 3 phantoms and 50 patients with a corresponding total number of 80 spinal metastases were included in this study. Fast spin echo T1- and T2- weighted MRI with and without surface coil intensity correction was routinely performed for all phantoms and patients. Phantoms were evaluated by means of variance to mean ratio of signal intensity on both T1- and T2- weighted MRI obtained with and without surface coil intensity correction. Spinal metastases were evaluated by image quality scores; reading time per case on both T1- and T2- weighted MRI obtained with and without surface coil intensity correction. Spinal metastases were diagnosed more successfully on MRI with surface coil intensity correction than on MRI with conventional surface coil technique. The variance to mean ratio of signal intensity was 53.36% for original T1-weighted MRI and 53.58% for original T2-weighted MRI. The variance to mean ratio of signal intensity was reduced to 18.99% for T1-weighted MRI with surface coil intensity correction and 22.77% for T2-weighted MRI with surface coil intensity correction. The overall image quality scores (interface conspicuity of lesion and details of lesion) were significantly higher than those of the original MRI. The reading time per case was shorter for MRI with surface coil intensity correction than for MRI without surface coil intensity correction. Phased-array surface coil intensity correction in MRIs of spinal metastases provides improvements in image quality that leads to more successfully detection and assessment of spinal metastases than original MRI.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    PubMed

    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. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. 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.

  16. Investigation of electrical characteristics of no-insulation coil wound with surface-processed HTS tape

    NASA Astrophysics Data System (ADS)

    Jeon, Haeryong; Lee, Woo Seung; Kim, Jinsub; Baek, Geonwoo; Jeon, Sangsu; Yoon, Yong Soo; Ko, Tae Kuk

    2017-08-01

    This paper deals with the electrical characteristics of no-insulation coil wound with surface-processed HTS tape. The bypassing current path through turn-to-turn contacts within a coil is formed in the no-insulation coil, and this bypassing current path determines two characteristics: 1) self-protection and 2) charge-discharge delay. The amplitude of bypassing current is determined by contact resistance between the turn-to-turn contacts of the no-insulation coil. The surface roughness of the HTS tape is one of the parameters to change the contact resistance. The HTS tapes were processed to roughen by bead blast and abrasive paper, and the no-insulation coil is fabricated using processed HTS tape. We have studied the charge-discharge delay and self-protecting characteristic of each no-insulation coil by 1) sudden discharge tests and 2) overcurrent tests. The FEM simulations of contact resistance of no-insulation coil were carried out. The contact surface resistance of a case processed by abrasive paper has almost three times larger than that of reference no-insulation coil, and a case processed by bead blast presents almost same contact surface resistance with reference no-insulation coil.

  17. Advantageous application of a surface coil to EPR irradiation in overhauser-enhanced MRI.

    PubMed

    Matsumoto, Shingo; Yamada, Kenichi; Hirata, Hiroshi; Yasukawa, Keiji; Hyodo, Fuminori; Ichikawa, Kazuhiro; Utsumi, Hideo

    2007-04-01

    The present study describes the advantageous application of a surface coil to electron paramagnetic resonance (EPR) irradiation in Overhauser-enhanced MRI (OMRI). OMRI is a double-resonance method for imaging free radicals based on the Overhauser effect. Proton NMR images are recorded without and with EPR irradiation of the free radical resonance, which results in a difference proton image that shows signal enhancement in spatial regions that contain the free radical. To obtain good signal enhancement in OMRI, very high RF power and a long EPR irradiation time are required. To improve sensitivity and shorten the image acquisition time, especially for localized (and topical) applications, we developed and tested a surface-coil-type EPR irradiation coil. Theoretical calculations and experimental data showed that EPR irradiation through the surface coil could ameliorate the localized Overhauser enhancement, which was related to the ratio of B(1) surface coil/B(1) volume coil in the region of interest (ROI), as expected. The increased sensitivity could also be converted into a shortened EPR irradiation time, resulting in fast data acquisition. For biomedical applications, the use of a surface coil (as opposed to a conventional volume coil) could decrease the total RF power deposition in the sample required to obtain the same Overhauser enhancement in the ROI.

  18. Comparison of a 32-channel head coil and a 2-channel surface coil for MR imaging of the temporomandibular joint at 3.0 T

    PubMed Central

    Spinner, Georg; Wyss, Michael; Filli, Lukas; Erni, Stefan; Ettlin, Dominik A; Ulbrich, Erika J; Kuhn, Felix P; Gallo, Luigi M; Andreisek, Gustav

    2016-01-01

    Objective: To quantitatively and qualitatively compare MRI of the temporomandibular joint (TMJ) using a standard TMJ surface coil and a head coil at 3.0 T. Methods: 22 asymptomatic volunteers were MR imaged using a 2-channel surface coil (standard TMJ coil) and a 32-channel head coil at 3.0 T (Philips Ingenia; Philips Healthcare, Netherlands). Imaging protocol consisted of an oblique sagittal proton density weighted turbo spin echo sequence (repetition time/echo time, 2700/26 ms). For quantitative assessment, a spherical phantom was imaged using the same sequence including a noise scan and a B1+ scan. Signal-to-noise ratio (SNR) maps and B1+ maps were calculated on a voxelwise basis. For qualitative evaluation, all volunteers underwent MRI of both TMJs with the jaw in the closed position. Two independent blinded readers assessed accuracy of TMJ anatomical representation and overall image quality on a 5-point scale. Quantitative and qualitative measurements were compared between coils using t-tests and Wilcoxon signed-rank test, respectively. Results: Quantitative analysis showed similar B1+ and significantly higher SNR for the head coil than the TMJ surface coil. Qualitative analysis showed significantly better visibility and delineation of clinically relevant anatomical structures of the TMJ, including the articular disc, bilaminar zone and lateral pterygoid muscle. Furthermore, better overall image quality was observed for the head coil than for the TMJ surface coil. Conclusions: A 32-channel head coil is preferable to a standard 2-channel TMJ surface coil when imaging the TMJ at 3.0 T, because it yields higher SNR, thus increasing accuracy of the anatomical representation of the TMJ. PMID:26837671

  19. Comparison of a 32-channel head coil and a 2-channel surface coil for MR imaging of the temporomandibular joint at 3.0 T.

    PubMed

    Manoliu, Andrei; Spinner, Georg; Wyss, Michael; Filli, Lukas; Erni, Stefan; Ettlin, Dominik A; Ulbrich, Erika J; Kuhn, Felix P; Gallo, Luigi M; Andreisek, Gustav

    2016-01-01

    To quantitatively and qualitatively compare MRI of the temporomandibular joint (TMJ) using a standard TMJ surface coil and a head coil at 3.0 T. 22 asymptomatic volunteers were MR imaged using a 2-channel surface coil (standard TMJ coil) and a 32-channel head coil at 3.0 T (Philips Ingenia; Philips Healthcare, Netherlands). Imaging protocol consisted of an oblique sagittal proton density weighted turbo spin echo sequence (repetition time/echo time, 2700/26 ms). For quantitative assessment, a spherical phantom was imaged using the same sequence including a noise scan and a B1+ scan. Signal-to-noise ratio (SNR) maps and B1+ maps were calculated on a voxelwise basis. For qualitative evaluation, all volunteers underwent MRI of both TMJs with the jaw in the closed position. Two independent blinded readers assessed accuracy of TMJ anatomical representation and overall image quality on a 5-point scale. Quantitative and qualitative measurements were compared between coils using t-tests and Wilcoxon signed-rank test, respectively. Quantitative analysis showed similar B1+ and significantly higher SNR for the head coil than the TMJ surface coil. Qualitative analysis showed significantly better visibility and delineation of clinically relevant anatomical structures of the TMJ, including the articular disc, bilaminar zone and lateral pterygoid muscle. Furthermore, better overall image quality was observed for the head coil than for the TMJ surface coil. A 32-channel head coil is preferable to a standard 2-channel TMJ surface coil when imaging the TMJ at 3.0 T, because it yields higher SNR, thus increasing accuracy of the anatomical representation of the TMJ.

  20. Markless Attenuation Correction for Carotid MRI Surface Receiver Coils in Combined PET/MR Imaging

    PubMed Central

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

    2015-01-01

    Purpose To evaluate the effect of attenuation of MR coils on quantitative carotid PET/MR exams. Additionally, to develop and evaluate automated attenuation correction method for flexible carotid MR coils was developed and evaluated. Methods 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 minutes 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. Results 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. Conclusions 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. PMID:26020273

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness

    NASA Astrophysics Data System (ADS)

    Andrzejczyk, Rafał; Muszyński, Tomasz

    2016-12-01

    The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow inside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.

  6. MLAA-based RF surface coil attenuation estimation in hybrid PET/MR imaging

    NASA Astrophysics Data System (ADS)

    Heußer, Thorsten; Rank, Christopher M.; Freitag, Martin T.; Kachelrieß, Marc

    2017-03-01

    Attenuation correction (AC) for both patient and hardware attenuation of the 511 keV annihilation photons is required for accurate PET quantification. In hybrid PET/MR imaging, AC for stationary hardware components such as patient table and MR head coil is performed using CT{derived attenuation templates. AC for flexible hardware components such as MR radiofrequency (RF) surface coils is more challenging. Registration{based approaches, aligning scaled CT{derived attenuation templates with the current patient position, have been proposed but are not used in clinical routine. Ignoring RF coil attenuation has been shown to result in regional activity underestimation values of up to 18 %. We propose to employ a modified version of the maximum{ likelihood reconstruction of attenuation and activity (MLAA) algorithm to obtain an estimate of the RF coil attenuation. Starting with an initial attenuation map not including the RF coil, the attenuation update of MLAA is applied outside the body outline only, allowing to estimate RF coil attenuation without changing the patient attenuation map. Hence, the proposed method is referred to as external MLAA (xMLAA). In this work, xMLAA for RF surface coil attenuation estimation is investigated using phantom and patient data acquired with a Siemens Biograph mMR. For the phantom data, average activity errors compared to the ground truth was reduced from -8:1% to +0:8% when using the proposed method. Patient data revealed an average activity underestimation of -6:1% for the abdominal region and -5:3% for the thoracic region when ignoring RF coil attenuation.

  7. Investigation of high-resolution functional magnetic resonance imaging by means of surface and array radiofrequency coils at 7 T.

    PubMed

    van der Zwaag, Wietske; Marques, José P; Hergt, Martin; Gruetter, Rolf

    2009-10-01

    In this investigation, high-resolution, 1x1x1-mm(3) functional magnetic resonance imaging (fMRI) at 7 T is performed using a multichannel array head coil and a surface coil approach. Scan geometry was optimized for each coil separately to exploit the strengths of both coils. Acquisitions with the surface coil focused on partial brain coverage, while whole-brain coverage fMRI experiments were performed with the array head coil. BOLD sensitivity in the occipital lobe was found to be higher with the surface coil than with the head array, suggesting that restriction of signal detection to the area of interest may be beneficial for localized activation studies. Performing independent component analysis (ICA) decomposition of the fMRI data, we consistently detected BOLD signal changes and resting state networks. In the surface coil data, a small negative BOLD response could be detected in these resting state network areas. Also in the data acquired with the surface coil, two distinct components of the positive BOLD signal were consistently observed. These two components were tentatively assigned to tissue and venous signal changes.

  8. 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.

  9. (1) H-(13) C independently tuned radiofrequency surface coil applied for in vivo hyperpolarized MRI.

    PubMed

    Cao, Peng; Zhang, Xiaoliang; Park, Ilwoo; Najac, Chloe; Nelson, Sarah J; Ronen, Sabrina; Larson, Peder E Z

    2016-11-01

    To develop a lump-element double-tuned common-mode-differential-mode (CMDM) radiofrequency (RF) surface coil with independent frequency tuning capacity for MRS and MRI applications. The presented design has two modes that can operate with different current paths, allowing independent frequency adjustment. The coil prototype was tested on the bench and then examined in phantom and in vivo experiments. Standard deviations of frequency and impedance fluctuations measured in one resonator, while changing the tuning capacitor of another resonator, were less than 13 kHz and 0.55 Ω. The unloaded S21 was -36 dB and -41 dB, while the unloaded Q factor was 260 and 287, for (13) C and (1) H, respectively. In vivo hyperpolarized (13) C MR spectroscopy data demonstrated the feasibility of using the CMDM coil to measure the dynamics of lactate, alanine, pyruvate and bicarbonate signal in a normal rat head along with acquiring (1) H anatomical reference images. Independent frequency tuning capacity was demonstrated in the presented lump-element double-tuned CMDM coil. This CMDM coil maintained intrinsically decoupled magnetic fields, which provided sufficient isolation between the two resonators. The results from in vivo experiments demonstrated high sensitivity of both the (1) H and (13) C resonators. Magn Reson Med 76:1612-1620, 2016. © 2015 International Society for Magnetic Resonance in Medicine. © 2015 International Society for Magnetic Resonance in Medicine.

  10. 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.

  11. High resolution MRI imaging at 1. 5T using surface coils

    SciTech Connect

    Blinder, R.A.; Herfkens, R.J.; Coleman, R.E.; Johnson, G.A.; Schenck, J.F.; Hart, H.R. Jr.; Foster, T.H.; Edelstein, W.A.

    1985-05-01

    The potential utility of high resolution MRI imaging in various pathologic conditions was explored. As the voxel size of MRI images is decreased the signal per pixel diminishes due to the geometric decrease in volume. In very high resolution images the signal can be small enough to be obscured by Johnson noise. High magnetic field strength (1.5T) coupled with surface coil imaging increases the signal to noise ratio. The surface coils used were single turn coils with diameters of 6 or 11 cm depending on the body part being imaged. A ''clam shell'' crossed coil was used for imaging the knees. Using a 1.5T prototype MRI imaging system we have obtained images with 14.5 cm field of view that are 256 by 256 pixels with a slice thickness of 3 mm. Good signal to noise is obtained using 2DTF imaging with only 2 excitations per phase encoding step (1 average). Images obtained of peripheral joints demonstrate articular cartilage, ligamentous structures, and trabeculae in medullary bone. These exams have demonstrated the changes of rheumatoid arthritis, and the extent of neoplastic involvement in bone. Images of the temporomandibular joint and the neck have been obtained. Parathyroid adenomas have been identified. Surface coil imaging and high magnetic fields allow for high resolution MRI imaging of various anatomic structures. Good signal to noise can be accomplished without extensive signal averaging so that reasonable imaging times and throughput can be realized with voxel dimensions of 0.6 x 0.6 x 3mm.

  12. 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.

  13. The knee: Surface-coil MR imaging at 1. 5 T

    SciTech Connect

    Beltran, J.; Noto, A.M.; Mosure, J.C.; Weiss, K.L.; Zuelzer, W.; Christoforidis, A.J.

    1986-06-01

    Seven normal knees (in five volunteers) and seven injured knees (in seven patients) were examined by high-resolution magnetic resonance (MR) imaging at 1.5 T with a surface coil. Seven medial meniscal tears, three anterior cruciate ligament tears, one posterior cruciate ligament avulsion, an old osteochondral fracture, femoral condylar chondro-malacia, and one case of semimembranous tendon reinsertion were identified. MR images correlated well with recent double-contrast arthrograms or results of surgery. All tears were identified in both the sagittal and coronal planes. Because of its ability to demonstrate small meniscal lesions and ligamentous injuries readily, MR imaging with a surface coil may eventually replace the more invasive arthrography.

  14. Performance of coils wound from long lengths of surface-coated, reacted, BSCCO-2212 conductor

    SciTech Connect

    Walker, M.S.; Hazelton, D.W.; Gardner, M.T.

    1996-10-01

    React-before-wind surface-coated BSCCO-2212 is being established as a relatively low cost HTS conductor for practical applications. Quality tape is presently being manufactured in 450-500m lengths at a cost estimated to be 1/3-1/5 of the industry costs of BSCCO-2223 powder-in-tube tape. Robust, mechanically sound coils for applications ranging from NMR insert magnets to transformer windings are being made from this BSCCO-2212 tape. The coils have performed consistently through test and thermal cycling without degradation and as projected from short sample measurements. A hybrid approach, which uses mainly BSCCO- 2212 augmented by BSCCO-2223 conductor in the high radial field end regions, is expected to halve magnet system costs.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Stochastization of Magnetic Field Surfaces in Tokamaks by an Inner Coil

    SciTech Connect

    Chavez-Alarcon, Esteban; Herrera-Velazquez, J. Julio E.; Braun-Gitler, Eliezer

    2006-12-04

    A 3-D code has been developed in order to simulate the magnetic field lines in circular cross-section tokamaks. The toroidal magnetic field can be obtained from the individual fields of circular coils arranged around the torus, or alternatively, as a ripple-less field. The poloidal field is provided by a given toroidal current density profile. Proposing initial conditions for a magnetic filed line, it is integrated along the toroidal angle coordinate, and Poincare maps can be obtained at any desired cross section plane. Following this procedure, the code allows the mapping of magnetic field surfaces for the axisymmetric case. For this work, the density current profile is chosen to be bell-shaped, so that realistic safety factor profiles can be obtained. This code is used in order to study the braking up of external surfaces when the symmetry is broken by an inner coil with tilted circular loops, with the purpose of modelling the behaviour of ergodic divertors, such as those devised for TEXTOR.

  1. 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

  2. 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.

  3. Characteristics of Surface Particle Motion of Coiled Waveguide Caused by Flexural Ultrasonic Waves

    NASA Astrophysics Data System (ADS)

    Xie, Shangping; Tanabe, Masayuki; Okubo, Kan; Tagawa, Norio; Moriya, Tadashi

    2008-05-01

    A traveling wave miniature ultrasonic motor has been developed using a helical coiled waveguide as a stator, and it has been applied to an intravascular ultrasound (IVUS) probe. In this motor, the elliptical motion of the surface particle due to flexural ultrasonic waves drives the rotor which can be placed inside or outside adjacent to the stator via frictional force. However, the fact that the rotational direction of the outer rotor is the reverse of that of the inner rotor at low frequencies of the flexural wave has not been clarified theoretically. In this study, the surface particle motion is investigated through finite element method (FEM) simulations, and the basis of the rotational directions is clarified.

  4. 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.

  5. High resolution surface coil magnetic resonance imaging of the joints: anatomic correlation.

    PubMed

    Middleton, W D; Macrander, S; Lawson, T L; Kneeland, J B; Cates, J D; Kellman, G M; Carrera, G F; Foley, W D; Jesmanowicz, A; Hyde, J S

    1987-07-01

    Magnetic resonance imaging appears to be a particularly promising approach to the evaluation of articular and periarticular abnormalities. Its ability to produce images in multiple planes directly (without reconstruction) provides a unique advantage over CT for the radiologist when he attempts to interpret the complex three dimensional anatomy of most joints. The inherent contrast resolution of MR is excellent, and with the use of surface coils, spatial resolution is sufficient to permit the identification of the small soft tissue structures in and around joints. Artifacts generated by respiratory and cardiac motion are not a problem in MRI of the joints as they are in MR scanning of the body. Based on all these qualities, we believe that MRI will play an important role in the diagnosis of joint abnormalities.

  6. 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.

  7. 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.

  8. Newly developed surface coil for endoluminal MRI, depiction of pig gastric wall layers and vascular architecture in ex vivo study.

    PubMed

    Morita, Yoshinori; Kutsumi, Hiromu; Yoshinaka, Hayato; Matsuoka, Yuichiro; Kuroda, Kagayaki; Gotanda, Masakazu; Sekino, Naomi; Kumamoto, Etsuko; Yoshida, Masaru; Inokuchi, Hideto; Azuma, Takeshi

    2009-01-01

    The purpose of this study was to visualize the gastric wall layers and to depict the vascular architecture in vitro by using resected porcine stomachs studied with high-spatial resolution magnetic resonance (MR) imaging. Normal dissected porcine stomach samples (n = 4) were examined with a 3 Tesla MR system using a newly developed surface coil. MR images were obtained by the surface coil as receiver and a head coil as transmitter. High-spatial-resolution spin-echo MR images were obtained with a field of view of 8 x 8 cm, a matrix of 256 x 128 and slice thicknesses of 3 and 5 mm. T1 and T2-weighted MR images clearly depicted the normal porcine gastric walls as consisting of four distinct layers. In addition, vascular architectures in proper muscle layers were also visualized, which were confirmed by histological examinations to correspond to blood vessels. High-spatial-resolution MR imaging using a surface coil placed closely to the gastric wall enabled the differentiation of porcine gastric wall layers and the depiction of the blood vessels in proper muscle layer in this experimental study.

  9. Magnetic Coiling

    NASA Image and Video Library

    2016-07-18

    One broad active region sported a wonderful example of coiled magnetic field lines over almost a four-day period (July 15-18, 2016). The magnetic lines are easily visible in this 171 Angstrom wavelength of extreme ultraviolet light be cause charged particles are spiraling along the lines. The active region is a hotbed of struggling magnetic forces that were pushing out above the sun's surface. http://photojournal.jpl.nasa.gov/catalog/PIA17911

  10. 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.

  11. The effect of MR surface coils on PET quantification in whole-body PET/MR: results from a pseudo-PET/MR phantom study.

    PubMed

    Tellmann, L; Quick, H H; Bockisch, A; Herzog, H; Beyer, T

    2011-05-01

    The use of magnetic resonance (MR) radiofrequency (RF) surface coils is a prerequisite for high-quality positron emission tomography (PET)/MR imaging. In lack of in-gantry transmission (TX) sources, the exact position of the RF coils is unknown in PET/MR, and may, therefore, lead to false attenuation correction (AC) of the emission (EM) data. The authors assess lesion and background quantification in AC-PET by mimicking different PET/MR imaging situations using a whole-body (WB) PET-only tomograph. Phantom experiments were performed on a PET tomograph with 68 Ge-rod TX sources. First, a 15-cm plastic cylinder was filled uniformly with [18F]-FDG to simulate a head study. Second, a NEMA NU-2001 image quality phantom (35 x 25 x 25 cm3) was filled uniformly with [18F]-FDG to simulate torso imaging. The phantom contained six lesions (10-38 mm diameter, lesion-to-background ratio 6:1) centred around a 5 cm diameter lung insert. EM and TX measurements were acquired with and without MR head (cylinder) and surface (NU-2001 phantom) RF coils in place. The following imaging situations were mimicked in both head and torso phantom studies: (1) PET scan without MR coils in EM and TX for reference, (2) PET scan with coils in both EM and TX, and (3) PET scan with coils in EM but without coils in TX. Two more set-ups were performed for the torso phantom: (4) PET scan with coils in EM only and phantom shifted slightly compared to (3), and (5) PET scan with coils in EM and TX following local displacement of the surface coils. PET EM data (1)-(4) were corrected for attenuation and scatter using cold TX data. Imaging situations (1)-(3) were repeated with the cylinder phantom and head coil in a combined PET/MR prototype system employing template-based AC. Head phantom: In case the MR head coils were not accounted for during AC (3), central and peripheral background activity concentration was underestimated by 13%-19% when compared to the reference setup (1). The effects of MR coil

  12. 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.

  13. 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)

  14. Four-channel surface coil array for 300-MHz pulsed EPR imaging: proof-of-concept experiments.

    PubMed

    Enomoto, Ayano; Hirata, Hiroshi; Matsumoto, Shingo; Saito, Keita; Subramanian, Sankaran; Krishna, Murali C; Devasahayam, Nallathamby

    2014-02-01

    Time-domain electron paramagnetic resonance imaging is currently a useful preclinical molecular imaging modality in experimental animals such as mice and is capable of quantitatively mapping hypoxia in tumor implants. The microseconds range relaxation times (T1 and T2) of paramagnetic tracers and the large bandwidths (tens of MHz) to be excited by electron paramagnetic resonance pulses for spatial encoding makes imaging of large objects a challenging task. The possibility of using multiple array coils to permit studies on large sized object is the purpose of the present work. Toward this end, the use of planar array coils in different configurations to image larger objects than cannot be fully covered by a single resonator element is explored. Multiple circular surface coils, which are arranged in a plane or at suitable angles mimicking a volume resonator, are used in imaging a phantom and a tumor-bearing mouse leg. The image was formed by combining the images collected from the individual coils with suitable scaling. The results support such a possibility. By multiplexing or interleaving the measurements from each element of such array resonators, one can scale up the size of the subject and at the same time reduce the radiofrequency power requirements and increase the sensitivity. Copyright © 2013 Wiley Periodicals, Inc.

  15. 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.

  16. 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.

  17. Diagnostic accuracy of surface coil MRI in assessing cartilaginous invasion in laryngeal tumours: Do we need contrast-agent administration?

    PubMed

    Preda, Lorenzo; Conte, Giorgio; Bonello, Luke; Giannitto, Caterina; Tagliabue, Elena; Raimondi, Sara; Ansarin, Mohssen; De Benedetto, Luigi; Cattaneo, Augusto; Maffini, Fausto; Bellomi, Massimo

    2017-05-05

    To assess the diagnostic accuracy of MRI performed using surface coils, with and without contrast medium, in predicting thyroid and cricoid cartilage infiltration in laryngeal tumours, and to investigate whether the radiologist's experience influences diagnostic accuracy. We retrospectively enrolled patients with biopsy-proven laryngeal cancer who had undergone preoperative staging MRI and open surgery. Two radiologists with different experience (senior vs. junior) reviewed the MR images without (session A1) and with contrast medium (session A2) separately. We calculated the accuracy of MRI with and without contrast medium in detecting infiltration of the thyroid and cricoid cartilages. Interobserver agreement was calculated by Cohen's Kappa (k). Forty-two patients were enrolled, for a total of 62 cartilages. In session A1 the senior and junior radiologists showed an accuracy of 85% and 71%, respectively, with k = 0.53 (0.33-0.72). In session A2 the senior and junior radiologists showed an accuracy of 84% and 77%, respectively, with k = 0.68 (0.49-0.86). Staging of laryngeal tumours with surface coil MRI showed good diagnostic accuracy in assessing cartilaginous infiltration. We observed similar values of diagnostic accuracy for the analysis performed with and without contrast medium for the senior radiologist. • Surface coil MRI demonstrated good accuracy in assessing laryngeal cartilage invasion. • The radiologist's experience can influence the diagnostic accuracy. • Gadolinium administration may increase interobserver concordance.

  18. 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.

  19. 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

  20. Design and application of a four-channel transmit/receive surface coil for functional cardiac imaging at 7T.

    PubMed

    Dieringer, Matthias A; Renz, Wolfgang; Lindel, Tomasz; Seifert, Frank; Frauenrath, Tobias; von Knobelsdorff-Brenkenhoff, Florian; Waiczies, Helmar; Hoffmann, Werner; Rieger, Jan; Pfeiffer, Harald; Ittermann, Bernd; Schulz-Menger, Jeanette; Niendorf, Thoralf

    2011-03-01

    To design and evaluate a four-channel cardiac transceiver coil array for functional cardiac imaging at 7T. A four-element cardiac transceiver surface coil array was developed with two rectangular loops mounted on an anterior former and two rectangular loops on a posterior former. specific absorption rate (SAR) simulations were performed and a B 1+ calibration method was applied prior to obtain 2D FLASH CINE (mSENSE, R = 2) images from nine healthy volunteers with a spatial resolution of up to 1 × 1 × 2.5 mm(3). Tuning and matching was found to be better than 10 dB for all subjects. The decoupling (S(21)) was measured to be >18 dB between neighboring loops, >20 dB for opposite loops, and >30 dB for other loop combinations. SAR values were well within the limits provided by the IEC. Imaging provided clinically acceptable signal homogeneity with an excellent blood-myocardium contrast applying the B 1+ calibration approach. A four-channel cardiac transceiver coil array for 7T was built, allowing for cardiac imaging with clinically acceptable signal homogeneity and an excellent blood-myocardium contrast. Minor anatomic structures, such as pericardium, mitral, and tricuspid valves and their apparatus, as well as trabeculae, were accurately delineated. Copyright © 2011 Wiley-Liss, Inc.

  1. 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.

  2. 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

  3. Magnetic resonance imaging for radiotherapy planning of brain cancer patients using immobilization and surface coils

    NASA Astrophysics Data System (ADS)

    Hanvey, S.; Glegg, M.; Foster, J.

    2009-09-01

    This study investigated the compatibility of a head and neck immobilization device with magnetic resonance imaging (MRI). The immobilization device is used to position a patient in the same way as when receiving a computed tomography (CT) scan for radiotherapy planning and radiation treatment. The advantage of using immobilization in MR is improved accuracy in CT/MR image registration enabling greater confidence in the delineation of structures. The main practical difficulty in using an immobilization device in MRI is that physical constraints make their use incompatible with head imaging coils. Within this paper we describe a method for MR imaging of the brain which allows the use of head and neck immobilization devices. By a series of image quality tests we obtained the same or better image quality as a multi-channel head coil.

  4. Magnetic resonance imaging for radiotherapy planning of brain cancer patients using immobilization and surface coils.

    PubMed

    Hanvey, S; Glegg, M; Foster, J

    2009-09-21

    This study investigated the compatibility of a head and neck immobilization device with magnetic resonance imaging (MRI). The immobilization device is used to position a patient in the same way as when receiving a computed tomography (CT) scan for radiotherapy planning and radiation treatment. The advantage of using immobilization in MR is improved accuracy in CT/MR image registration enabling greater confidence in the delineation of structures. The main practical difficulty in using an immobilization device in MRI is that physical constraints make their use incompatible with head imaging coils. Within this paper we describe a method for MR imaging of the brain which allows the use of head and neck immobilization devices. By a series of image quality tests we obtained the same or better image quality as a multi-channel head coil.

  5. Rectangle Surface Coil Array in a Grid Arrangement for Resonance Imaging

    DTIC Science & Technology

    2016-02-13

    switchable array, RF magnetic field, NQR, MRI, NMR , tuning, decoupling I. INTRODUCTION ESONANCE imaging can be accomplished using Nuclear Magnetic...Resonance ( NMR ) or Nuclear Quadrupole Resonance (NQR) techniques. REF [1] and [6] explain the differences between NMR and NQR. What NMR and NQR...4. Ohliger, M. “An introduction to coil array design for parallel MRI” NMR IN BIOMEDICINE NMR Biomed. 2006; 19: 300–315 Published online in Wiley

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. Design of a radiative surface coil array element at 7 T: the single-side adapted dipole antenna.

    PubMed

    Raaijmakers, A J E; Ipek, O; Klomp, D W J; Possanzini, C; Harvey, P R; Lagendijk, J J W; van den Berg, C A T

    2011-11-01

    Ultra high field MR imaging (≥7 T) of deeply located targets in the body is facing some radiofrequency-field related challenges: interference patterns, reduced penetration depth, and higher Specific Absorbtion Ratio (SAR) levels. These can be alleviated by redesigning the elements of the transmit or transceive array. This is because at these high excitation field (B(1) ) frequencies, conventional array element designs may have become suboptimal. In this work, an alternative design approach is presented, regarding coil array elements as antennas. Following this approach, the Poynting vector of the element should be oriented towards the imaging target region. The single-side adapted dipole antenna is a novel design that fulfills this requirement. The performance of this design as a transmit coil array element has been characterized by comparison with three other, more conventional designs using finite difference time domain (FDTD) simulations and B +1 measurements on a phantom. Results show that the B +1 level at the deeper regions is higher while maintaining relatively low SAR levels. Also, the B +1 field distribution is more symmetrical and more uniform, promising better image homogeneity. Eight radiative antennas have been combined into a belt-like surface array for prostate imaging. T(1) -weighted (T1W) and T(2) -weighted (T2W) volunteer images are presented along with B +1 measurements to demonstrate the improved efficiency. Copyright © 2011 Wiley Periodicals, Inc.

  11. 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)

  12. Cardiac MRI in mice at 9.4 Tesla with a transmit-receive surface coil and a cardiac-tailored intensity-correction algorithm.

    PubMed

    Sosnovik, David E; Dai, Guangping; Nahrendorf, Matthias; Rosen, Bruce R; Seethamraju, Ravi

    2007-08-01

    To evaluate the use of a transmit-receive surface (TRS) coil and a cardiac-tailored intensity-correction algorithm for cardiac MRI in mice at 9.4 Tesla (9.4T). Fast low-angle shot (FLASH) cines, with and without delays alternating with nutations for tailored excitation (DANTE) tagging, were acquired in 13 mice. An intensity-correction algorithm was developed to compensate for the sensitivity profile of the surface coil, and was tailored to account for the unique distribution of noise and flow artifacts in cardiac MR images. Image quality was extremely high and allowed fine structures such as trabeculations, valve cusps, and coronary arteries to be clearly visualized. The tag lines created with the surface coil were also sharp and clearly visible. Application of the intensity-correction algorithm improved signal intensity, tissue contrast, and image quality even further. Importantly, the cardiac-tailored properties of the correction algorithm prevented noise and flow artifacts from being significantly amplified. The feasibility and value of cardiac MRI in mice with a TRS coil has been demonstrated. In addition, a cardiac-tailored intensity-correction algorithm has been developed and shown to improve image quality even further. The use of these techniques could produce significant potential benefits over a broad range of scanners, coil configurations, and field strengths. (c) 2007 Wiley-Liss, Inc.

  13. Functional MRI in conscious rats using a chronically implanted surface coil.

    PubMed

    Martin, Chris J; Kennerley, Aneurin J; Berwick, Jason; Port, Michael; Mayhew, John E W

    2013-09-01

    To establish procedures for functional MRI (fMRI) in rats without the need for anesthetic agents. Rats were trained to habituate to restraint in a harness and scanner noise. Under anesthesia, rats were then prepared with a cranial implant that permitted stabilization of the head during subsequent imaging experiments. The cranial implant included an radiofrequency (RF) coil that was used to transmit and receive radiofrequency signals during imaging. Further training was then conducted to habituate the animals to head fixation whilst in the MR scanner. Using this method, we were able to successfully and repeatedly record BOLD fMRI responses to hypercapnia and whisker stimulation in awake rats. Electrical stimulation of the whisker pad produced a ∼7% increase in BOLD signal in the corresponding barrel cortex as well as adjacent negative BOLD responses, whilst hypercapnia produced larger increases in BOLD signal amplitude. This methodology leaves the face and limbs free from obstruction, making possible a range of behavioral or sensory stimulation protocols. Further development of this animal model could enable traditional behavioral neuroscience techniques to be combined with modern functional neuroimaging. Copyright © 2012 Wiley Periodicals, Inc., a Wiley company.

  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. 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

  16. 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.

  17. Heterodimeric coiled-coil interactions of human GABAB receptor

    PubMed Central

    Burmakina, Svetlana; Geng, Yong; Chen, Yan; Fan, Qing R.

    2014-01-01

    Metabotropic GABAB receptor is a G protein-coupled receptor that mediates inhibitory neurotransmission in the CNS. It functions as an obligatory heterodimer of GABAB receptor 1 (GBR1) and GABAB receptor 2 (GBR2) subunits. The association between GBR1 and GBR2 masks an endoplasmic reticulum (ER) retention signal in the cytoplasmic region of GBR1 and facilitates cell surface expression of both subunits. Here, we present, to our knowledge, the first crystal structure of an intracellular coiled-coil heterodimer of human GABAB receptor. We found that polar interactions buried within the hydrophobic core determine the specificity of heterodimer pairing. Disruption of the hydrophobic coiled-coil interface with single mutations in either subunit impairs surface expression of GBR1, confirming that the coiled-coil interaction is required to inactivate the adjacent ER retention signal of GBR1. The coiled-coil assembly buries an internalization motif of GBR1 at the heterodimer interface. The ER retention signal of GBR1 is not part of the core coiled-coil structure, suggesting that it is sterically shielded by GBR2 upon heterodimer formation. PMID:24778228

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Gabapentin Modulates HCN4 Channel Voltage-Dependence

    PubMed Central

    Tae, Han-Shen; Smith, Kelly M.; Phillips, A. Marie; Boyle, Kieran A.; Li, Melody; Forster, Ian C.; Hatch, Robert J.; Richardson, Robert; Hughes, David I.; Graham, Brett A.; Petrou, Steven; Reid, Christopher A.

    2017-01-01

    Gabapentin (GBP) is widely used to treat epilepsy and neuropathic pain. There is evidence that GBP can act on hyperpolarization-activated cation (HCN) channel-mediated Ih in brain slice experiments. However, evidence showing that GBP directly modulates HCN channels is lacking. The effect of GBP was tested using two-electrode voltage clamp recordings from human HCN1, HCN2, and HCN4 channels expressed in Xenopus oocytes. Whole-cell recordings were also made from mouse spinal cord slices targeting either parvalbumin positive (PV+) or calretinin positive (CR+) inhibitory neurons. The effect of GBP on Ih was measured in each inhibitory neuron population. HCN4 expression was assessed in the spinal cord using immunohistochemistry. When applied to HCN4 channels, GBP (100 μM) caused a hyperpolarizing shift in the voltage of half activation (V1/2) thereby reducing the currents. Gabapentin had no impact on the V1/2 of HCN1 or HCN2 channels. There was a robust increase in the time to half activation for HCN4 channels with only a small increase noted for HCN1 channels. Gabapentin also caused a hyperpolarizing shift in the V1/2 of Ih measured from HCN4-expressing PV+ inhibitory neurons in the spinal dorsal horn. Gabapentin had minimal effect on Ih recorded from CR+ neurons. Consistent with this, immunohistochemical analysis revealed that the majority of CR+ inhibitory neurons do not express somatic HCN4 channels. In conclusion, GBP reduces HCN4 channel-mediated currents through a hyperpolarized shift in the V1/2. The HCN channel subtype selectivity of GBP provides a unique tool for investigating HCN4 channel function in the central nervous system. The HCN4 channel is a candidate molecular target for the acute analgesic and anticonvulsant actions of GBP. PMID:28871229

  3. 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.

  4. Coiling of a viscous filament

    NASA Astrophysics Data System (ADS)

    Samuel, A. D. T.; Ryu, W. S.; Mahadevan, L.

    1997-11-01

    A classic demonstration of fluid buckling is a daily occurence at the breakfast table, where a continuous stream of viscous fluid (honey) is often poured onto a flat surface (toast) from a sufficient height. The thin fluid filament quickly settles into a steady state; near the surface it bends into a helical shape while simultaneously rotating about the vertical and is laid out in a regular coil. This behavior is reminiscent of the coiling of a falling flexible rope. We derive a simple scaling law that predicts the coiling frequency in terms of the filament radius and the flow rate. We also verify this scaling law with the results of experiments.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Protein detection by Western blot via coiled-coil interactions.

    PubMed

    Boucher, Cyril; St-Laurent, Gilles; Jolicoeur, Mario; Crescenzo, Gregory De; Durocher, Yves

    2010-04-01

    We propose an approach for the detection of proteins by Western blot that takes advantage of the high-affinity interaction occurring between two de novo designed peptides, the E and K coils. As a model system, K coil-tagged epidermal growth factor (EGF) was revealed with secreted alkaline phosphatase (SeAP) tagged with E coil (SeAP-Ecoil) as well as with biotinylated E coil. In that respect, we first produced purified SeAP-Ecoil and verified its ability to interact with K coil peptides by surface plasmon resonance biosensing. We demonstrated that protein detection with Ecoil-biotin was more specific than with SeAP-Ecoil. We then showed that our approach is as sensitive as conventional detection strategies relying on nickel-nitrilotriacetic acid-horseradish peroxidase (Ni-NTA-HRP), anti-His-HRP, or anti-EGF. Altogether, our results indicate that the E/K coiled-coil system is a good alternative for protein detection by Western blot. Crown Copyright 2009. Published by Elsevier Inc. All rights reserved.

  11. 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.

  12. 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

  13. 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.

  14. In vivo proton observed carbon edited (POCE) (13) C magnetic resonance spectroscopy of the rat brain using a volumetric transmitter and receive-only surface coil on the proton channel.

    PubMed

    Kumaragamage, Chathura; Madularu, Dan; Mathieu, Axel P; De Feyter, Henk; Rajah, M Natasha; Near, Jamie

    2017-05-12

    In vivo carbon-13 ((13) C) MR spectroscopy (MRS) is capable of measuring energy metabolism and neuroenergetics, noninvasively in the brain. Indirect ((1) H-[(13) C]) MRS provides sensitivity benefits compared with direct (13) C methods, and normally includes a (1) H surface coil for both localization and signal reception. The aim was to develop a coil platform with homogenous B1+ and use short conventional pulses for short echo time proton observed carbon edited (POCE) MRS. A (1) H-[(13) C] MRS coil platform was designed with a volumetric resonator for (1) H transmit, and surface coils for (1) H reception and (13) C transmission. The Rx-only (1) H surface coil nullifies the requirement for a T/R switch before the (1) H preamplifier; the highpass filter and preamplifier can be placed proximal to the coil, thus minimizing sensitivity losses inherent with POCE-MRS systems described in the literature. The coil platform was evaluated with a PRESS-POCE sequence (TE = 12.6 ms) on a rat model. The coil provided excellent localization, uniform spin nutation, and sensitivity. (13) C labeling of Glu-H4 and Glx-H3 peaks, and the Glx-H2 peaks were observed approximately 13 and 21 min following the infusion of 1-(13) C glucose, respectively. A convenient and sensitive platform to study energy metabolism and neurotransmitter cycling is presented. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  15. 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

  16. 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.

  17. 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

  18. Optimizing T2-weighted magnetic resonance sequences for surface coil microimaging of the eye with regard to lid, eyeball and head moving artifacts.

    PubMed

    Obata, Takayuki; Uemura, Koji; Nonaka, Hiroi; Tamura, Mitsuru; Tanada, Shuji; Ikehira, Hiroo

    2006-01-01

    To acquire high-resolution magnetic resonance (MR) images, we developed a new blinking artifact reduced pulse (BARP) sequence with a surface coil specialized for microscopic imaging (47 mm in diameter). To reduce eye movement, we ascertained that the subjects' eyes were kept open and fixated to the target in the 1.5-T MR gantry. To reduce motion artifacts from blinking, we inserted rest periods for blinking (1.5 s within every 5 s) during MR scanning (T2-weighted fast spin echo; repetition time, 5 s; echo time, 100 ms; echo train, 11; matrix, 256 x 128; field of view, 5 cm; 1-mm thickness x 30 slices). Three scans (100 s x 3) were performed for each normal subject, and they were added together after automatic adjustment for location to reduce quality loss caused by head motion. T2-weighted MR images were acquired with a high resolution and a high signal-to-noise ratio. Motion artifacts were reduced with BARP, as compared with those with random blinking. Intraocular structures such as the iris and ciliary muscles were clearly visualized. Because the whole eye can be covered with a 1-mm thickness by this method, three-dimensional maps can easily be generated from the obtained images. The application of BARP with a surface coil of the human eye might become a useful and widely adopted procedure for MR microimaging.

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

    PubMed

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

    2016-02-01

    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 [Formula: see text] and receive [Formula: see text] 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 [Formula: see text] and [Formula: see text]. 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.

  20. TRPV4 channels: physiological and pathological role in cardiovascular system.

    PubMed

    Randhawa, Puneet Kaur; Jaggi, Amteshwar Singh

    2015-11-01

    TRPV4 channels are non-selective cation channels permeable to Ca(2+), Na(+), and Mg(2+) ions. Recently, TRPV4 channels have received considerable attention as these channels are widely expressed in the cardiovascular system including endothelial cells, cardiac fibroblasts, vascular smooth muscles, and peri-vascular nerves. Therefore, these channels possibly play a pivotal role in the maintenance of cardiovascular homeostasis. TRPV4 channels critically regulate flow-induced arteriogenesis, TGF-β1-induced differentiation of cardiac fibroblasts into myofibroblasts, and heart failure-induced pulmonary edema. These channels also mediate hypoxia-induced increase in proliferation and migration of pulmonary artery smooth muscle cells and progression of pulmonary hypertension. These channels also maintain flow-induced vasodilation and preserve vascular function by directly activating Ca(2+)-dependent KCa channels. Furthermore, these may also induce vasodilation and maintain blood pressure indirectly by evoking the release of NO, CGRP, and substance P. The present review discusses the evidences and the potential mechanisms implicated in diverse responses including arteriogenesis, cardiac remodeling, congestive heart failure-induced pulmonary edema, pulmonary hypertension, flow-induced dilation, regulation of blood pressure, and hypoxic preconditioning.

  1. 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.

  2. Coiled-Coil Formation on Lipid Bilayers—Implications for Docking and Fusion Efficiency

    PubMed Central

    Pähler, Gesa; Panse, Cornelia; Diederichsen, Ulf; Janshoff, Andreas

    2012-01-01

    Coiled-coil formation of four different oligopeptides was characterized in solution, on hydrogels, and on membranes by employing circular dichroism spectroscopy, surface plasmon resonance spectroscopy, attenuated total reflection infrared spectroscopy, and ellipsometry. Peptide sequences rich in either glutamic acid (E: E3Cys, i-E3Cys) or lysine (K: K3Cys, i-K3Cys) were used to represent minimal mimics of eukaryotic SNARE motifs. Half of the peptides were synthesized in reverse sequence, so that parallel and antiparallel heptad coiled-coil structures were formed. Either E-peptides or K-peptides were attached covalently to phospholipid anchors via maleimide chemistry, and served as receptors for the recognition of the corresponding binding partners added to solution. Attenuated total reflection infrared spectroscopy of single bilayers confirmed the formation of coiled-coil complexes at the membrane interface. Coiled-coil formation in solution, as compared with association at the membrane surface, displays considerably larger binding constants that are largely attributed to loss of translational entropy at the interface. Finally, the fusogenicity of the various coiled-coil motifs was explored, and the results provide clear evidence that hemifusion followed by full fusion requires a parallel orientation of α-helices, whereas antiparallel oriented coiled-coil motifs display only docking. PMID:23283228

  3. Magnetoencephalographically directed review of high-spatial-resolution surface-coil MR images improves lesion detection in patients with extratemporal epilepsy.

    PubMed

    Moore, Kevin R; Funke, Michael E; Constantino, Tawnya; Katzman, Gregory L; Lewine, Jeffrey David

    2002-12-01

    To determine whether (a) interictal magnetoencephalographic (MEG) epileptiform activity corresponds to anatomic abnormalities at magnetic resonance (MR) imaging, (b) high-spatial-resolution MR imaging depicts lesions in regions without MEG spike activity, (c) MEG-directed review of high-spatial-resolution MR images enables detection of abnormalities not apparent on conventional MR images, and (d) MEG information results in a greater number of diagnosed lesions at re-review of conventional MR images. Twenty patients with neocortical epilepsy were evaluated with MEG, conventional brain MR imaging with a head coil, and high-spatial-resolution MR imaging with either a surface coil (n = 17) or a high-spatial-resolution birdcage coil (n = 3). Abnormal MEG foci were compared with corresponding anatomic areas on conventional and high-spatial-resolution MR images to determine the presence (concordance) or absence (discordance) of anatomic lesions corresponding to foci of abnormal MEG activity. Forty-four epileptiform MEG foci were identified. Twelve foci (27%) were concordant with an anatomic abnormality at high-spatial-resolution MR imaging, and 32 foci (73%) were discordant. Results of high-spatial-resolution MR imaging were normal in eight patients, and 23 lesions were detected in the remaining 12 patients. Twelve lesions (52%) were concordant with abnormal MEG epileptiform activity, and 11 (48%) were discordant (ie, there was normal MEG activity in the region of the anatomic abnormality). At retrospective reevaluation of conventional MR images with MEG guidance, four occult gray matter migration lesions that had initially been missed were observed. An additional patient with MEG-concordant postoperative gliosis was readily identified with high-spatial-resolution MR images but not with conventional MR images. Review of MEG-localized epileptiform areas on high-spatial-resolution MR images enables detection of epileptogenic neocortical lesions, some of which are occult on

  4. Parallel imaging of head with a dedicated multi-coil on a 0.4T open MRI.

    PubMed

    Takizawa, Masahiro; Shimoda, Takahide; Nonaka, Masayuki; Mochizuki, Hiroyuki; Kawasaki, Shinji; Takeuchi, Hiroyuki; Tachibana, Miki; Takahashi, Tetsuhiko

    2005-01-01

    Parallel imaging is widely used for cylindrical magnetic resonance imaging (MRI); however, few studies apply parallel imaging to open MRI. We previously developed a parallel method called "RAPID" (rapid acquisition through a parallel imaging design) for imaging the heart on a 0.7T open MRI apparatus, and we have now developed a RAPID head coil and shading correction algorithm for imaging the brain with a 0.4T open MRI apparatus. Images acquired with RAPID were compared with those acquired using a conventional quadrature-detection (QD) head coil. The images were acquired using a dedicated 4-channel RF receiving coil consisting of a solenoid coil and surface coils. For MRI of the brain, we developed 2 methods to acquire the necessary calibration data: a pre-scan method that acquires the calibration data before the main scans and a self-calibration method that acquires the calibration data and imaging data simultaneously. We also modified the algorithm for calculating the shading distribution so that it only uses acquired image data and then corrects the shading. RAPID was applied for T1-weighted, T2-weighted, fluid-attenuation inversion recovery (FLAIR), time-of-flight (TOF), and diffusion-weighted echo-planar (DW-EPI) imaging. The RAPID images had no visible unfolded artifacts or motion artifacts. Images with the same contrast as that with a conventional QD coil were acquired using the RAPID coil and shading correction. These preliminary results show that RAPID can be applied to imaging of the head using a 0.4T open MRI apparatus.

  5. Evolutionary Patterns in Coiled-Coils

    PubMed Central

    Surkont, Jaroslaw; Pereira-Leal, Jose B.

    2015-01-01

    Models of protein evolution are used to describe evolutionary processes, for phylogenetic analyses and homology detection. Widely used general models of protein evolution are biased toward globular domains and lack resolution to describe evolutionary processes for other protein types. As three-dimensional structure is a major constraint to protein evolution, specific models have been proposed for other types of proteins. Here, we consider evolutionary patterns in coiled-coil forming proteins. Coiled-coils are widespread structural domains, formed by a repeated motif of seven amino acids (heptad repeat). Coiled-coil forming proteins are frequently rods and spacers, structuring both the intracellular and the extracellular spaces that often form protein interaction interfaces. We tested the hypothesis that due to their specific structure the associated evolutionary constraints differ from those of globular proteins. We showed that substitution patterns in coiled-coil regions are different than those observed in globular regions, beyond the simple heptad repeat. Based on these substitution patterns we developed a coiled-coil specific (CC) model that in the context of phylogenetic reconstruction outperforms general models in tree likelihood, often leading to different topologies. For multidomain proteins containing both a coiled-coil region and a globular domain, we showed that a combination of the CC model and a general one gives higher likelihoods than a single model. Finally, we showed that the model can be used for homology detection to increase search sensitivity for coiled-coil proteins. The CC model, software, and other supplementary materials are available at http://www.evocell.org/cgl/resources (last accessed January 29, 2015). PMID:25577198

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. Development and evaluation of a multichannel endorectal RF coil for prostate MRI at 7T in combination with an external surface array.

    PubMed

    Ertürk, M Arcan; Tian, Jinfeng; Van de Moortele, Pierre-François; Adriany, Gregor; Metzger, Gregory J

    2016-06-01

    To develop and evaluate a sterilizable multichannel endorectal coil (ERC) for use in combination with an external surface array (ESA) for high-resolution anatomical and functional studies of the prostate at 7T. A two-loop ERC (ERC-2L) and a microstrip-loop ERC (ERC-ML) were compared at 7T in terms of transmit and receive performance. The best-performing ERC was evaluated alone and in combination with the ESA through 1) simulations on both phantom and an anatomically correct numerical human model to assess B1+ transmit and specific absorption rate (SAR) efficiencies, and 2) phantom experiments to calculate B1+ transmit efficiency and signal-to-noise ratio (SNR). Phantom studies were also performed to look at heating when using the ERC as a transmitter and for comparing the new coil against a single-channel balloon-type ERC (ERC-b). High-resolution magnetic resonance imaging (MRI) acquisitions were performed on a single healthy subject using the two-channel ERC combined with the ESA. Compared to the ERC-ML, the ERC-2L demonstrated 20% higher SAR efficiency and higher SNR 3 cm from the coil. The presence of a tuned and detuned ERC-2L did not alter the peak local SAR of the ESA alone; however, the detuned ERC-2L had 45% less peak local SAR around the rectum compared to the tuned ERC-2L. The receive-only version of the ERC-2L improved the SNR 4.7-fold and 1.3-fold compared to the ESA and ERC-b, respectively. In combination with the ESA, the ERC-2L supported in-plane voxel-size of 0.36 × 0.36 mm(2) in T2 -weighted anatomic imaging. The reusable ERC-2L combined with an ESA offers a high SNR imaging platform for translational studies of the prostate at 7T. J. Magn. Reson. Imaging 2016;43:1279-1287. © 2015 Wiley Periodicals, Inc.

  14. 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.

  15. Increased Vessel Depiction of the Carotid Bifurcation with a Specialized 16-Channel Phased Array Coil at 3T

    PubMed Central

    Tate, Quinn; Kim, Seong-Eun; Treiman, Gerald; Parker, Dennis L.; Hadley, J. Rock

    2012-01-01

    The purpose of this work was to design and construct a multi-channel receive-only RF coil for 3 Tesla magnetic resonance imaging of the human carotid artery and bifurcation with optimized signal to noise ratio in the carotid vessels along the full extent of the neck. A neck phantom designed to match the anatomy of a subject with a neck representing the body habitus often seen in subjects with carotid arterial disease, was constructed. Sixteen circular coil elements were arranged on a semi-rigid fiberglass former that closely fit the shape of the phantom, resulting in a 16-channel bilateral phased array coil. Comparisons were made between this coil and a typical 4-channel carotid coil in a study of 10 carotid vessels in 5 healthy volunteers. The 16-channel carotid coil showed a 73% average improvement in signal to noise ratio (SNR) at the carotid bifurcation. This coil also maintained an SNR greater than the peak SNR of the 4-channel coil over a vessel length of 10 cm. The resulting increase in SNR improved vessel depiction of the carotid arteries over an extended field of view, and demonstrated better image quality for higher parallel imaging reduction factors compared to the 4-channel coil. PMID:22777692

  16. Increased vessel depiction of the carotid bifurcation with a specialized 16-channel phased array coil at 3T.

    PubMed

    Tate, Quinn; Kim, Seong-Eun; Treiman, Gerald; Parker, Dennis L; Hadley, J Rock

    2013-05-01

    The purpose of this work was to design and construct a multichannel receive-only radiofrequency coil for 3T magnetic resonance imaging of the human carotid artery and bifurcation with optimized signal-to-noise ratio (SNR) in the carotid vessels along the full extent of the neck. A neck phantom designed to match the anatomy of a subject with a neck representing the body habitus often seen in subjects with carotid arterial disease was constructed. Sixteen circular coil elements were arranged on a semirigid fiberglass former that closely fit the shape of the phantom, resulting in a 16-channel bilateral phased array coil. Comparisons were made between this coil and a typical 4-channel carotid coil in a study of 10 carotid vessels in five healthy volunteers. The 16-channel carotid coil showed a 73% average improvement in SNR at the carotid bifurcation. This coil also maintained an SNR greater than the peak SNR of the 4-channel coil over a vessel length of 10 cm. The resulting increase in SNR improved vessel depiction of the carotid arteries over an extended field of view, and demonstrated better image quality for higher parallel imaging reduction factors compared to the 4-channel coil. Copyright © 2012 Wiley Periodicals, Inc.

  17. An 8-channel RF coil array for carotid artery MR imaging in humans at 3 T.

    PubMed

    Hu, Xiaoqing; Zhang, Lei; Zhang, Xiaoliang; Zhu, Huabin; Chen, Xiao; Zhang, Yongqin; Chung, Yiu-Cho; Liu, Xin; Zheng, Hairong; Li, Ye

    2016-04-01

    Carotid artery diseases due to plaque buildup at the carotid bifurcation are a leading cause of stroke. Accurate plaque quantification and characterization of plaque composition and morphology by magnetic resonance imaging (MRI) is essential to identifying high-risk patients. Difficulties in detecting plaque, which is physically small, and the unique physiological structure of the carotid artery make use of a radio frequency (RF) coil array with high resolution, large longitudinal coverage, and deep penetration ideal for clinical examinations. The goal of this project was to design and fabricate a sensitive RF coil array with sufficient imaging coverage and signal-to-noise ratio (SNR) for carotid artery imaging at 3 T. Based on clinical requirements and the anatomical structure of the human carotid artery, an 8-channel carotid coil array was designed and fabricated for 3 T MRI of the carotid artery in humans. The performance of the proposed 8-channel carotid coil array was validated through bench tests and MR imaging experiments on a 3 T whole body MRI scanner. Its performance was also compared experimentally to the performance of a commercial 4-channel phased array carotid coil designed by Machnet BV (Machnet BV coil, Roden, Netherlands). The 8-channel carotid coil array performed significantly better in imaging the carotid artery than the commercial 4-channel Machnet BV coil in terms of the SNR, coverage, and penetration depth. In parallel imaging, the proposed 8-channel carotid coil array demonstrated a much lower maximum value and average value of the geometry factor in the region of interest. Carotid artery images acquired in vivo using the proposed 8-channel carotid artery coil and the commercial 4-channel Machnet BV coil were also compared, demonstrating the former's potential for clinical diagnosis. Based on the analyses of phantom and in vivo imaging studies, the proposed 8-channel carotid coil array has the potential for use in clinical diagnosis

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Sticky water surfaces: Helix-coil transitions suppressed in a cell-penetrating peptide at the air-water interface

    NASA Astrophysics Data System (ADS)

    Schach, Denise; Globisch, Christoph; Roeters, Steven J.; Woutersen, Sander; Fuchs, Adrian; Weiss, Clemens K.; Backus, Ellen H. G.; Landfester, Katharina; Bonn, Mischa; Peter, Christine; Weidner, Tobias

    2014-12-01

    GALA is a 30 amino acid synthetic peptide consisting of a Glu-Ala-Leu-Ala repeat and is known to undergo a reversible structural transition from a disordered to an α-helical structure when changing the pH from basic to acidic values. In its helical state GALA can insert into and disintegrate lipid membranes. This effect has generated much interest in GALA as a candidate for pH triggered, targeted drug delivery. GALA also serves as a well-defined model system to understand cell penetration mechanisms and protein folding triggered by external stimuli. Structural transitions of GALA in solution have been studied extensively. However, cell penetration is an interfacial effect and potential biomedical applications of GALA would involve a variety of surfaces, e.g., nanoparticles, lipid membranes, tubing, and liquid-gas interfaces. Despite the apparent importance of interfaces in the functioning of GALA, the effect of surfaces on the reversible folding of GALA has not yet been studied. Here, we use sum frequency generation vibrational spectroscopy (SFG) to probe the structural response of GALA at the air-water interface and IR spectroscopy to follow GALA folding in bulk solution. We combine the SFG data with molecular dynamics simulations to obtain a molecular-level picture of the interaction of GALA with the air-water interface. Surprisingly, while the fully reversible structural transition was observed in solution, at the water-air interface, a large fraction of the GALA population remained helical at high pH. This "stickiness" of the air-water interface can be explained by the stabilizing interactions of hydrophobic leucine and alanine side chains with the water surface.

  8. 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

  9. 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.

  10. Prospective motion correction using tracking coils.

    PubMed

    Qin, Lei; Schmidt, Ehud J; Tse, Zion Tsz Ho; Santos, Juan; Hoge, William S; Tempany-Afdhal, Clare; Butts-Pauly, Kim; Dumoulin, Charles L

    2013-03-01

    Intracavity imaging coils provide higher signal-to-noise than surface coils and have the potential to provide higher spatial resolution in shorter acquisition times. However, images from these coils suffer from physiologically induced motion artifacts, as both the anatomy and the coils move during image acquisition. We developed prospective motion-correction techniques for intracavity imaging using an array of tracking coils. The system had <50 ms latency between tracking and imaging, so that the images from the intracavity coil were acquired in a frame of reference defined by the tracking array rather than by the system's gradient coils. Two-dimensional gradient-recalled and three-dimensional electrocardiogram-gated inversion-recovery-fast-gradient-echo sequences were tested with prospective motion correction using ex vivo hearts placed on a moving platform simulating both respiratory and cardiac motion. Human abdominal tests were subsequently conducted. The tracking array provided a positional accuracy of 0.7 ± 0.5 mm, 0.6 ± 0.4 mm, and 0.1 ± 0.1 mm along the X, Y, and Z directions at a rate of 20 frames-per-second. The ex vivo and human experiments showed significant image quality improvements for both in-plane and through-plane motion correction, which although not performed in intracavity imaging, demonstrates the feasibility of implementing such a motion-correction system in a future design of combined tracking and intracavity coil. Copyright © 2012 Wiley Periodicals, Inc.

  11. 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

  12. 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.

  13. 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.

  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. 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.

  16. 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).

  17. 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.

  18. 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.

  19. 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.

  20. FLASH proton density imaging for improved surface coil intensity correction in quantitative and semi-quantitative SSFP perfusion cardiovascular magnetic resonance.

    PubMed

    Nielles-Vallespin, Sonia; Kellman, Peter; Hsu, Li-Yueh; Arai, Andrew E

    2015-02-17

    A low excitation flip angle (α < 10°) steady-state free precession (SSFP) proton-density (PD) reference scan is often used to estimate the B1-field inhomogeneity for surface coil intensity correction (SCIC) of the saturation-recovery (SR) prepared high flip angle (α = 40-50°) SSFP myocardial perfusion images. The different SSFP off-resonance response for these two flip angles might lead to suboptimal SCIC when there is a spatial variation in the background B0-field. The low flip angle SSFP-PD frames are more prone to parallel imaging banding artifacts in the presence of off-resonance. The use of FLASH-PD frames would eliminate both the banding artifacts and the uneven frequency response in the presence of off-resonance in the surface coil inhomogeneity estimate and improve homogeneity of semi-quantitative and quantitative perfusion measurements. B0-field maps, SSFP and FLASH-PD frames were acquired in 10 healthy volunteers to analyze the SSFP off-resonance response. Furthermore, perfusion scans preceded by both FLASH and SSFP-PD frames from 10 patients with no myocardial infarction were analyzed semi-quantitatively and quantitatively (rest n = 10 and stress n = 1). Intra-subject myocardial blood flow (MBF) coefficient of variation (CoV) over the whole left ventricle (LV), as well as intra-subject peak contrast (CE) and upslope (SLP) standard deviation (SD) over 6 LV sectors were investigated. In the 6 out of 10 cases where artifacts were apparent in the LV ROI of the SSFP-PD images, all three variability metrics were statistically significantly lower when using the FLASH-PD frames as input for the SCIC (CoVMBF-FLASH = 0.3 ± 0.1, CoVMBF-SSFP = 0.4 ± 0.1, p = 0.03; SDCE-FLASH = 10 ± 2, SDCE-SSFP = 32 ± 7, p = 0.01; SDSLP-FLASH = 0.02 ± 0.01, SDSLP-SSFP = 0.06 ± 0.02, p = 0.03). Example rest and stress data sets from the patient pool demonstrate that the low flip angle SSFP protocol

  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. 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.

  3. 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.

  4. Molecular basis of coiled-coil oligomerization-state specificity.

    PubMed

    Ciani, Barbara; Bjelic, Saša; Honnappa, Srinivas; Jawhari, Hatim; Jaussi, Rolf; Payapilly, Aishwarya; Jowitt, Thomas; Steinmetz, Michel O; Kammerer, Richard A

    2010-11-16

    Coiled coils are extensively and successfully used nowadays to rationally design multistranded structures for applications, including basic research, biotechnology, nanotechnology, materials science, and medicine. The wide range of applications as well as the important functions these structures play in almost all biological processes highlight the need for a detailed understanding of the factors that control coiled-coil folding and oligomerization. Here, we address the important and unresolved question why the presence of particular oligomerization-state determinants within a coiled coil does frequently not correlate with its topology. We found an unexpected, general link between coiled-coil oligomerization-state specificity and trigger sequences, elements that are indispensable for coiled-coil formation. By using the archetype coiled-coil domain of the yeast transcriptional activator GCN4 as a model system, we show that well-established trimer-specific oligomerization-state determinants switch the peptide's topology from a dimer to a trimer only when inserted into the trigger sequence. We successfully confirmed our results in two other, unrelated coiled-coil dimers, ATF1 and cortexillin-1. We furthermore show that multiple topology determinants can coexist in the same trigger sequence, revealing a delicate balance of the resulting oligomerization state by position-dependent forces. Our experimental results should significantly improve the prediction of the oligomerization state of coiled coils. They therefore should have major implications for the rational design of coiled coils and consequently many applications using these popular oligomerization domains.

  5. CC+: a relational database of coiled-coil structures

    PubMed Central

    Testa, Oliver D.; Moutevelis, Efrosini; Woolfson, Derek N.

    2009-01-01

    We introduce the CC+ Database, a detailed, searchable repository of coiled-coil assignments, which is freely available at http://coiledcoils.chm.bris.ac.uk/ccplus. Coiled coils were identified using the program SOCKET, which locates coiled coils based on knobs-into-holes packing of side chains between α-helices. A method for determining the overall sequence identity of coiled-coil sequences was introduced to reduce statistical bias inherent in coiled-coil data sets. There are two points of entry into the CC+ Database: the ‘Periodic Table of Coiled-coil Structures’, which presents a graphical path through coiled-coil space based on manually validated data, and the ‘Dynamic Interface’, which allows queries of the database at different levels of complexity and detail. The latter entry level, which is the focus of this article, enables the efficient and rapid compilation of subsets of coiled-coil structures. These can be created and interrogated with increasingly sophisticated pull-down, keyword and sequence-based searches to return detailed structural and sequence information. Also provided are means for outputting the retrieved coiled-coil data in various formats, including PyMOL and RasMol scripts, and Position-Specific Scoring Matrices (or amino-acid profiles), which may be used, for example, in protein-structure prediction. PMID:18842638

  6. Exploring the conserved water site and hydration of a coiled-coil trimerisation motif: a MD simulation study.

    PubMed

    Dolenc, Jozica; Baron, Riccardo; Missimer, John H; Steinmetz, Michel O; van Gunsteren, Wilfred F

    2008-07-21

    The solvent structure and dynamics around ccbeta-p, a 17-residue peptide that forms a parallel three-stranded alpha-helical coiled coil in solution, was analysed through 10 ns explicit solvent molecular dynamics (MD) simulations at 278 and 330 K. Comparison with two corresponding simulations of the monomeric form of ccbeta-p was used to investigate the changes of hydration upon coiled-coil formation. Pronounced peaks in the solvent density distribution between residues Arg8 and Glu13 of neighbouring helices show the presence of water bridges between the helices of the ccbeta-p trimer; this is in agreement with the water sites observed in X-ray crystallography experiments. Interestingly, this water site is structurally conserved in many three-stranded coiled coils and, together with the Arg and Glu residues, forms part of a motif that determines three-stranded coiled-coil formation. Our findings show that little direct correlation exists between the solvent density distribution and the temporal ordering of water around the trimeric coiled coil. The MD-calculated effective residence times of up to 40 ps show rapid exchange of surface water molecules with the bulk phase, and indicate that the solvent distribution around biomolecules requires interpretation in terms of continuous density distributions rather than in terms of discrete molecules of water. Together, our study contributes to understanding the principles of three-stranded coiled-coil formation.

  7. Coiled-coil length: Size does matter.

    PubMed

    Surkont, Jaroslaw; Diekmann, Yoan; Ryder, Pearl V; Pereira-Leal, Jose B

    2015-12-01

    Protein evolution is governed by processes that alter primary sequence but also the length of proteins. Protein length may change in different ways, but insertions, deletions and duplications are the most common. An optimal protein size is a trade-off between sequence extension, which may change protein stability or lead to acquisition of a new function, and shrinkage that decreases metabolic cost of protein synthesis. Despite the general tendency for length conservation across orthologous proteins, the propensity to accept insertions and deletions is heterogeneous along the sequence. For example, protein regions rich in repetitive peptide motifs are well known to extensively vary their length across species. Here, we analyze length conservation of coiled-coils, domains formed by an ubiquitous, repetitive peptide motif present in all domains of life, that frequently plays a structural role in the cell. We observed that, despite the repetitive nature, the length of coiled-coil domains is generally highly conserved throughout the tree of life, even when the remaining parts of the protein change, including globular domains. Length conservation is independent of primary amino acid sequence variation, and represents a conservation of domain physical size. This suggests that the conservation of domain size is due to functional constraints. © 2015 Wiley Periodicals, Inc.

  8. 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.

  9. 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.

  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. 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.

  12. 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.

  13. 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

  14. Performance of large-size superconducting coil in 0.21T MRI system.

    PubMed

    Lee, K H; Cheng, M C; Chan, K C; Wong, K K; Yeung, Simon S M; Lee, K C; Ma, Q Y; Yang, Edward S

    2004-11-01

    A high-temperature superconductor (HTS) was used on magnetic resonance imaging (MRI) receiver coils to improve image quality because of its intrinsic low electrical resistivity. Typical HTS coils are surface coils made of HTS thin-film wafers. Their applications are severely limited by the field of view (FOV) of the surface coil configuration, and the improvement in image quality by HTS coil is also reduced as the ratio of sample noise to coil noise increases. Therefore, previous HTS coils are usually used to image small in vitro samples, small animals, or peripheral human anatomies. We used large-size HTS coils (2.5-, 3.5-, and 5.5-in mean diameter) to enhance the FOV and we evaluated their performance through phantom and human MR images. Comparisons were made among HTS surface coils, copper surface coils, and cool copper surface coils in terms of the signal-to-noise ratio (SNR) and sensitivity profile of the images. A theoretical model prediction was also used to compare against the experimental result. We then selected several human body parts, including the wrist, feet, and head, to illustrate the advantage of HTS coil over copper coil when used in human imaging. The results show an SNR gain of 200% for 5.5-in HTS coil versus same size copper coils, while for 2.5- and 3.5-in coils it is 250%. We also address the various factors that affect the performance of large size HTS coils, including the coil-to-sample spacing due to cryogenic probe and the coil-loading effect.

  15. Ocular MR imaging: evaluation of different coil setups in a phantom study.

    PubMed

    Erb-Eigner, Katharina; Warmuth, Carsten; Taupitz, Matthias; Bertelmann, Eckart; Hamm, Bernd; Asbach, Patrick

    2013-01-01

    Small loop surface coils are generally recommended for ocular magnetic resonance (MR) imaging, but the optimal coil setup has not been systematically investigated. In this phantom study, we investigated which coil setup of those coils available for our MR imaging system provides the highest signal-to-noise ratio (SNR) in ocular MR imaging at 1.5 tesla. Using a phantom to simulate the eyeball and the orbital fat, we employed loop surface coils of 4- and 6-cm diameter and a multi-channel head coil to obtain images using a T1-weighted spin-echo sequence and then measured the SNR for each coil and coil combination. Use of the 6-cm loop coil alone yielded the highest mean SNR (27.5). Even in superficial regions (mesial and temporal), the SNR was higher using the 6-cm loop coil (33.6 and 45.5) than the 4-cm loop coil (28.0 and 33.8). Additional use of the head coil reduced the mean SNR to 10.4. This quantitative analysis suggests that use of a 6-cm loop surface coil offers the best results in ocular MR imaging. Combinations of loop coils or additional use of a head coil cannot be recommended because higher noise degrades image quality.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. Computer-assisted design of surface coils used in magnetic resonance imaging. III. The design and construction of two long twin axial antennae for imaging of the whole human spine.

    PubMed

    Yamanashi, W S; Lester, P D; Letcher, J H

    1989-01-01

    Two modified folded dipole MRI surface coils were designed, constructed and tested. These antenna which are long twin axial lines use the effective distributive capacitance resulting from the distance between two longitudinal elements to provide tuning. The principal advantage of this type of antenna is the ability to image longer objects such as vertebrae, spinal cord, and longer portions of the extremities. This type of antenna shows less localized high intensity in the image due to a more evenly distributed current pickup from the sample. The coils were designed by calculating theoretical magnetic field distribution for the twin axial coils. These were obtained by integrating the Biot-Savart equation. This gave excellent agreement with an MR image of a di-electrically uniform phantom. As antennae of this sort are nonlinear in response, giving rise to an image intensity nonuniformity, computer software for the MR image was developed to correct the image intensity profile over the experimental volume. The software significantly improved the image quality by reducing the saturated intensity of the region near the antenna, thereby revealing detailed structure of the tissue being imaged.

  1. 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.

  2. 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.

  3. The use of coiled-coil interactions for the analysis and micropreparative isolation of adenomatous polyposis coli protein complexes.

    PubMed

    Catimel, B; Faux, M C; Nerrie, M; Rothacker, J; Otvos, L J; Wade, J D; Nice, E C; Burgess, A W

    2001-12-01

    The coiled coil is a common structural motif found both as the dominant structure in fibrous proteins and as an oligomerization domain in a variety of cytoskeletal and extracellular matrix proteins. Coiled-coils typically consist of two to four helices that are supercoiled around one another in either parallel or antiparallel orientations. In the past few years our knowledge of the structure and specificity of coiled coil interactions has increased, allowing the de novo design and preparation of coiled-coils with well-defined structure and specificity. Indeed, the design and synthesis of a peptide that binds specifically to a single coiled-coil-containing protein, adenomatous polyposis coli (APC) has been reported. We have optimized solid-phase synthesis techniques to produce a modified form of the anti-APC peptide that contains a biotin moiety specifically placed so as to allow selective orientation onto the surface of a biosensor or affinity support. These peptide surfaces have been used to both monitor and purify APC and APC complexes from cellular extracts.

  4. 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.

  5. 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

  6. 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.

  7. Prospective motion correction using tracking coils

    PubMed Central

    Qin, Lei; Schmidt, Ehud J; Tse, Zion Tsz Ho; Santos, Juan; Hoge, William S.; Tempany-Afdhal, Clare; Butts-Pauly, Kim; Dumoulin, Charles L

    2012-01-01

    Intra-cavity imaging coils provide higher signal-to-noise than surface coils, and have the potential to provide higher spatial resolution in shorter acquisition times. However, images from these coils suffer from physiologically-induced motion artifacts, since both the anatomy and the coils move during image acquisition. We developed prospective motion correction techniques for intra-cavity imaging using an array of tracking coils. The system had <50ms latency between tracking and imaging, so that the images from the intra-cavity coil were acquired in a frame of reference defined by the tracking array rather than by the system’s gradient coils. 2D Gradient-Recalled (GRASS) and 3D ECG-gated Inversion-Recovery-Fast-Gradient-Echo (IR-FGRE) sequences were tested with prospective motion correction using ex-vivo hearts placed on a moving platform simulating both respiratory and cardiac motion. Human abdominal tests were subsequently conducted. The tracking array provided a positional accuracy of 0.7±0.5mm, 0.6±0.4mm, and 0.1±0.1mm along the X, Y and Z directions at a rate of 20 frames-per-second. The ex-vivo and human experiments showed significant image quality improvements for both in-plane and through-plane motion correction, which although not performed in intra-cavity imaging, demonstrates the feasibility of implementing such a motion correction system in a future design of combined tracking and intra-cavity coil. PMID:22565377

  8. 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.

  9. 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.

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

    PubMed Central

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

    2016-01-01

    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. PMID:26786101

  11. 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

  12. Local control of TRPV4 channels by AKAP150-targeted PKC in arterial smooth muscle

    PubMed Central

    Mercado, Jose; Baylie, Rachael; Navedo, Manuel F.; Yuan, Can; Scott, John D.; Nelson, Mark T.

    2014-01-01

    Transient receptor potential vanilloid 4 (TRPV4) channels are Ca2+-permeable, nonselective cation channels expressed in multiple tissues, including smooth muscle. Although TRPV4 channels play a key role in regulating vascular tone, the mechanisms controlling Ca2+ influx through these channels in arterial myocytes are poorly understood. Here, we tested the hypothesis that in arterial myocytes the anchoring protein AKAP150 and protein kinase C (PKC) play a critical role in the regulation of TRPV4 channels during angiotensin II (AngII) signaling. Super-resolution imaging revealed that TRPV4 channels are gathered into puncta of variable sizes along the sarcolemma of arterial myocytes. Recordings of Ca2+ entry via single TRPV4 channels (“TRPV4 sparklets”) suggested that basal TRPV4 sparklet activity was low. However, Ca2+ entry during elementary TRPV4 sparklets was ∼100-fold greater than that during L-type CaV1.2 channel sparklets. Application of the TRPV4 channel agonist GSK1016790A or the vasoconstrictor AngII increased the activity of TRPV4 sparklets in specific regions of the cells. PKC and AKAP150 were required for AngII-induced increases in TRPV4 sparklet activity. AKAP150 and TRPV4 channel interactions were dynamic; activation of AngII signaling increased the proximity of AKAP150 and TRPV4 puncta in arterial myocytes. Furthermore, local stimulation of diacylglycerol and PKC signaling by laser activation of a light-sensitive Gq-coupled receptor (opto-α1AR) resulted in TRPV4-mediated Ca2+ influx. We propose that AKAP150, PKC, and TRPV4 channels form dynamic subcellular signaling domains that control Ca2+ influx into arterial myocytes. PMID:24778429

  13. 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.

  14. Heterotrimeric Coiled Coils with Core Residue Urea Side Chains

    PubMed Central

    Diss, Maria L.; Kennan, Alan J.

    2009-01-01

    We report several coiled coil heterotrimers with varying core residue buried polar groups, all with Tm values > 43° C. Introduction of new synthetic side chain structures, including some terminating in mono-substituted ureas, diversifies the pool of viable core residue candidates. A study of core charge pairings demonstrates that, unlike dimeric systems, trimeric coiled coils do not tolerate guanidine-guanidine contacts, even in the presence of a compensating carboxylate. Overall, the roster of feasible coiled coil designs is significantly expanded. PMID:19032043

  15. Distance constraints on activation of TRPV4 channels by AKAP150-bound PKCα in arterial myocytes.

    PubMed

    Tajada, Sendoa; Moreno, Claudia M; O'Dwyer, Samantha; Woods, Sean; Sato, Daisuke; Navedo, Manuel F; Santana, L Fernando

    2017-06-05

    TRPV4 (transient receptor potential vanilloid 4) channels are Ca(2+)-permeable channels that play a key role in regulating vascular tone. In arterial myocytes, opening of TRPV4 channels creates local increases in Ca(2+) influx, detectable optically as "TRPV4 sparklets." TRPV4 sparklet activity can be enhanced by the action of the vasoconstrictor angiotensin II (AngII). This modulation depends on the activation of subcellular signaling domains that comprise protein kinase C α (PKCα) bound to the anchoring protein AKAP150. Here, we used super-resolution nanoscopy, patch-clamp electrophysiology, Ca(2+) imaging, and mathematical modeling approaches to test the hypothesis that AKAP150-dependent modulation of TRPV4 channels is critically dependent on the distance between these two proteins in the sarcolemma of arterial myocytes. Our data show that the distance between AKAP150 and TRPV4 channel clusters varies with sex and arterial bed. Consistent with our hypothesis, we further find that basal and AngII-induced TRPV4 channel activity decays exponentially as the distance between TRPV4 and AKAP150 increases. Our data suggest a maximum radius of action of ∼200 nm for local modulation of TRPV4 channels by AKAP150-associated PKCα. © 2017 Tajada et al.

  16. RF Magnetic Field Uniformity of Rectangular Planar Coils for Resonance Imaging

    DTIC Science & Technology

    2016-02-04

    which can also be applied to Magnetic Resonance Imaging ( MRI ). Index Terms—NQR, NMR, rectangle coil, planar coil, overlap, tuning, decoupling, RF...related to nuclear magnetic resonance (NMR) and its offspring, magnetic resonance imaging ( MRI ). One significant advantage of NQR is the absence...pulsed RF excitation [1]. These observed signals are usually detected using a surface coil. Surface coil arrays are used in unilateral NMR scans

  17. 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.

  18. 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

  19. 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.

  20. Coil optimisation for transcranial magnetic stimulation in realistic head geometry.

    PubMed

    Koponen, Lari M; Nieminen, Jaakko O; Mutanen, Tuomas P; Stenroos, Matti; Ilmoniemi, Risto J

    Transcranial magnetic stimulation (TMS) allows focal, non-invasive stimulation of the cortex. A TMS pulse is inherently weakly coupled to the cortex; thus, magnetic stimulation requires both high current and high voltage to reach sufficient intensity. These requirements limit, for example, the maximum repetition rate and the maximum number of consecutive pulses with the same coil due to the rise of its temperature. To develop methods to optimise, design, and manufacture energy-efficient TMS coils in realistic head geometry with an arbitrary overall coil shape. We derive a semi-analytical integration scheme for computing the magnetic field energy of an arbitrary surface current distribution, compute the electric field induced by this distribution with a boundary element method, and optimise a TMS coil for focal stimulation. Additionally, we introduce a method for manufacturing such a coil by using Litz wire and a coil former machined from polyvinyl chloride. We designed, manufactured, and validated an optimised TMS coil and applied it to brain stimulation. Our simulations indicate that this coil requires less than half the power of a commercial figure-of-eight coil, with a 41% reduction due to the optimised winding geometry and a partial contribution due to our thinner coil former and reduced conductor height. With the optimised coil, the resting motor threshold of abductor pollicis brevis was reached with the capacitor voltage below 600 V and peak current below 3000 A. The described method allows designing practical TMS coils that have considerably higher efficiency than conventional figure-of-eight coils. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. The asymptotic structure of a slender coiling fluid thread

    NASA Astrophysics Data System (ADS)

    Blount, Maurice; Lister, John

    2010-11-01

    The buckling of a viscous fluid thread as it falls through air onto a stationary surface is a well-known breakfast-time phenomenon which exhibits a rich variety of dynamical regimes [1]. Since the bending resistance of a slender thread is small, bending motion is largely confined to a short region of coiling near the surface. If the height of fall is large enough, then the thread above the coiling region forms a `tail' that falls nearly vertically under gravity but is deflected slightly due to forces exerted on it by the coil. Although it is possible to use force balances in the coil to estimate scalings for the coiling frequency, we analyse the solution structure of the entire thread in the asymptotic limit of a very slender thread and thereby include the dynamic interaction between the coil and the tail. Quantitative predictions of the coiling frequency are obtained which demonstrate the existence of leading-order corrections to scalings previously derived. In particular, we show that in the regime where the deflection of the tail is governed by a balance between centrifugal acceleration, hoop stress and gravity, the tail behaves as a flexible circular pendulum that is forced by bending stress exerted by the coil. The amplitude of the response is calculated and the previously observed resonance when the coiling frequency coincides with one of the eigenfrequencies of a free flexible pendulum is thereby explained. [1] N.M. Ribe et al., J. Fluid Mech. 555, 275-297.

  2. 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).

  3. Fabrication of superconductor coils

    NASA Astrophysics Data System (ADS)

    Dorris, S. E.; Dusek, J. T.; Picciolo, J. J.; Leu, H. J.; Singh, J. P.; Cazzato, A.; Poeppel, R. B.

    1989-10-01

    Small coils of superconducting YBa2Cu3O(7-x)(123) can be formed in the green state using a layered superconductor/insulator tape. In this approach, the insulator prevents contact between the turns of the coil during firing. The insulator must be chemically compatible with 123 during firing, and ideally should match 123 with respect to firing shrinkage and thermal expansion. Fabrication of small coils from the layered superconductor/insulator composites 123/Y2BaCuO5 and 123/BaCuO2 will be discussed. The issue of chemical compatibility will be addressed, and measurements of the firing shrinkage and thermal expansion will be presented for 123 and the two insulators Y2BaO5 and BaCuO2. In addition, the superconducting properties of 123 in the composites will be presented.

  4. 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

  5. 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.

  6. 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

  7. 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

  8. Characteristics of Kcnn4 channels in the apical membranes of an intestinal epithelial cell line.

    PubMed

    Basalingappa, Kanthesh M; Rajendran, Vazhaikkurichi M; Wonderlin, William F

    2011-11-01

    Intermediate-conductance K(+) (Kcnn4) channels in the apical and basolateral membranes of epithelial cells play important roles in agonist-induced fluid secretion in intestine and colon. Basolateral Kcnn4 channels have been well characterized in situ using patch-clamp methods, but the investigation of Kcnn4 channels in apical membranes in situ has been hampered by a layer of mucus that prevents seal formation. In the present study, we used patch-clamp methods to characterize Kcnn4 channels in the apical membrane of IEC-18 cells, a cell line derived from rat small intestine. A monolayer of IEC-18 cells grown on a permeable support is devoid of mucus, and tight junctions enable selective access to the apical membrane. In inside-out patches, Ca(2+)-dependent K(+) channels observed with iberiotoxin (a Kcnma1/large-conductance, Ca(2+)-activated K(+) channel blocker) and apamin (a Kcnn1-3/small-conductance, Ca(2+)-activated K(+) channel blocker) present in the pipette solution exhibited a single-channel conductance of 31 pS with inward rectification. The currents were reversibly blocked by TRAM-34 (a Kcnn4 blocker) with an IC(50) of 8.7 ± 2.0 μM. The channels were not observed when charybdotoxin, a peptide inhibitor of Kcnn4 channels, was added to the pipette solution. TRAM-34 was less potent in inhibiting Kcnn4 channels in patches from apical membranes than in patches from basolateral membranes, which was consistent with a preferential expression of Kcnn4c and Kcnn4b isoforms in apical and basolateral membranes, respectively. The expression of both isoforms in IEC-18 cells was confirmed by RT-PCR and Western blot analyses. This is the first characterization of Kcnn4 channels in the apical membrane of intestinal epithelial cells.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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…

  15. 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…

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Adrenergic Regulation of HCN4 Channel Requires Protein Association with β2-Adrenergic Receptor*

    PubMed Central

    Greene, Derek; Kang, Seungwoo; Kosenko, Anastasia; Hoshi, Naoto

    2012-01-01

    β1- and β2-adrenergic receptors utilize different signaling mechanisms to control cardiac function. Recent studies demonstrated that β2-adrenergic receptors (β2ARs) colocalize with some ion channels that are critical for proper cardiac function. Here, we demonstrate that β2ARs form protein complexes with the pacemaker HCN4 channel, as well as with other subtypes of HCN channels. The adrenergic receptor-binding site was identified at a proximal region of the N-terminal tail of the HCN4 channel. A synthetic peptide derived from the β2AR-binding domain of the HCN4 channel disrupted interaction between HCN4 and β2AR. In addition, treatment with this peptide prevented adrenergic augmentation of pacemaker currents and spontaneous contraction rates but did not affect adrenergic regulation of voltage-gated calcium currents. These results suggest that the ion channel-receptor complex is a critical mechanism in ion channel regulation. PMID:22613709

  4. Adrenergic regulation of HCN4 channel requires protein association with β2-adrenergic receptor.

    PubMed

    Greene, Derek; Kang, Seungwoo; Kosenko, Anastasia; Hoshi, Naoto

    2012-07-06

    β(1)- and β(2)-adrenergic receptors utilize different signaling mechanisms to control cardiac function. Recent studies demonstrated that β(2)-adrenergic receptors (β(2)ARs) colocalize with some ion channels that are critical for proper cardiac function. Here, we demonstrate that β(2)ARs form protein complexes with the pacemaker HCN4 channel, as well as with other subtypes of HCN channels. The adrenergic receptor-binding site was identified at a proximal region of the N-terminal tail of the HCN4 channel. A synthetic peptide derived from the β(2)AR-binding domain of the HCN4 channel disrupted interaction between HCN4 and β(2)AR. In addition, treatment with this peptide prevented adrenergic augmentation of pacemaker currents and spontaneous contraction rates but did not affect adrenergic regulation of voltage-gated calcium currents. These results suggest that the ion channel-receptor complex is a critical mechanism in ion channel regulation.

  5. 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.

  6. Degradation analysis of REBCO coils

    NASA Astrophysics Data System (ADS)

    Ma, D. X.; Matsumoto, S.; Teranishi, R.; Ohmura, T.; Kiyoshi, T.; Otsuka, A.; Hamada, M.; Maeda, H.; Yanagisawa, Y.; Nakagome, H.; Suematsu, H.

    2014-08-01

    RE-Ba-Cu-O (REBCO) layer-wound coils were operated to investigate their properties under electromagnetic forces in an external magnetic field of up to 17.2 T. While REBCO coils were successfully operated under electromagnetic forces over 200 MPa, some showed degradation after quenching. To develop high-temperature superconducting (HTS) magnets, the reasons for the degradation of REBCO coils should be investigated. In this study, the degraded REBCO coils were carefully rewound. The critical current (Ic) of the rewound REBCO conductor was measured to check the damaged parts in the degraded REBCO coils, and the possible causes for the degradation were discussed.

  7. 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.

  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. A 32-channel coil system for MR vessel wall imaging of intracranial and extracranial arteries at 3T.

    PubMed

    Hu, Xiaoqing; Li, Ye; Zhang, Lei; Zhang, Xiaoliang; Liu, Xin; Chung, Yiu-Cho

    2017-02-01

    To develop a RF coil system for joint imaging of intracranial and extracranial arterial vessel wall at 3T. The coil system consists of a 24-channel head coil combined with an 8-channel carotid coil. It is compared with a standard coil configuration (12-channel head coil+4-channel neck coil+8-channel carotid coil) for SNR and g-factors in phantoms and healthy volunteers. The clinical relevance of the proposed coil system is also evaluated in patients. In phantom experiments, the SNR of the proposed coil system is 53% higher than the maximum SNR of the standard coil configuration at the center of the phantom which usually corresponds to the intracranial region of the head. The g-factors of the proposed coil system in the sagittal plane are lower than the standard coil configuration (by 10.8% and 26.6% for R=2 and 4 respectively) in the same experiment. In healthy volunteer experiments, 55% of the pixels have SNR above 100 for the proposed coil system, which is 33% more than that of the standard coil configuration. The maximum g-factors in the standard configuration are higher than those from the new coil design by 12% at R=2 and up to 36% at R=4 in the sagittal plane. In patients, in-vivo intracranial and extracranial arterial wall images at an isotropic spatial resolution of 0.6mm can be acquired using the proposed coil system. Plaques are well depicted from the images. The performance of the proposed coil set is superior to the standard coil configuration, providing high SNR, low g-factor and good spatial coverage needed for simultaneous high resolution imaging of intracranial and extracranial arterial walls. Images acquired in 7.6min using the proposed coil system can achieve an isotropic spatial resolution of 0.6mm and can be used to depict plaques on the intracranial and extracranial arterial walls in patients. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. New head gradient coil design and construction techniques.

    PubMed

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

    2014-05-01

    To design and build a head insert gradient coil to use in conjunction with body gradients for superior imaging. The use of the boundary element method to solve for a gradient coil wire pattern on an arbitrary surface allowed us to incorporate engineering changes into the electromagnetic design of a gradient coil directly. Improved wire pattern design was combined with robust manufacturing techniques and novel cooling methods. 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. The ability to adapt an electromagnetic design to necessary changes from an engineering perspective leads to superior coil performance. Copyright © 2013 Wiley Periodicals, Inc.

  11. 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

  12. 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.

  13. Coil configurations for low aspect ratio stellerators

    SciTech Connect

    Rome, J.; Morris, R.; Hirshman, S.; Fowler, R.; Merkel, P.

    1989-01-01

    Using the NESCOIL code, it is possible to find a surface current distribution which can create a given last closed flux surface. Thus, almost any stellarator configuration can be created with either helical or modular currents. In particular, we have succeeded in finding current distributions which generate the optimized ATF-II configuration described in Hirshman's paper. As the aspect ratio of the configuration is decreased, or the plasma-to-coil distance is increased, the harmonic content of the surface currents is increased. This makes it a challenge to cut the distribution into either discrete helical or modular coils which are attractive from an engineering point of view. Several approaches to this problem are discussed. There have been some hints of promising configurations, but to date, none of them are satisfactory. 2 refs., 7 figs.

  14. 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.

  15. 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.

  16. [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

  17. 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.

  18. 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.

  19. Distinct roles of molecular chaperones HSP90α and HSP90β in the biogenesis of KCNQ4 channels.

    PubMed

    Gao, Yanhong; Yechikov, Sergey; Vazquez, Ana E; Chen, Dongyang; Nie, Liping

    2013-01-01

    Loss-of-function mutations in the KCNQ4 channel cause DFNA2, a subtype of autosomal dominant non-syndromic deafness that is characterized by progressive sensorineural hearing loss. Previous studies have demonstrated that the majority of the pathogenic KCNQ4 mutations lead to trafficking deficiency and loss of KCNQ4 currents. Over the last two decades, various strategies have been developed to rescue trafficking deficiency of pathogenic mutants; the most exciting advances have been made by manipulating activities of molecular chaperones involved in the biogenesis and quality control of the target protein. However, such strategies have not been established for KCNQ4 mutants and little is known about the molecular chaperones governing the KCNQ4 biogenesis. To identify KCNQ4-associated molecular chaperones, a proteomic approach was used in this study. As a result, two major molecular chaperones, HSP70 and HSP90, were identified and then confirmed by reciprocal co-immunoprecipitation assays, suggesting that the HSP90 chaperone pathway might be involved in the KCNQ4 biogenesis. Manipulating chaperone expression further revealed that two different isoforms of HSP90, the inducible HSP90α and the constitutive HSP90β, had opposite effects on the cellular level of the KCNQ4 channel; that HSP40, HSP70, and HOP, three key components of the HSP90 chaperone pathway, were crucial in facilitating KCNQ4 biogenesis. In contrast, CHIP, a major E3 ubiquitin ligase, had an opposite effect. Collectively, our data suggest that HSP90α and HSP90β play key roles in controlling KCNQ4 homeostasis via the HSP40-HSP70-HOP-HSP90 chaperone pathway and the ubiquitin-proteasome pathway. Most importantly, we found that over-expression of HSP90β significantly improved cell surface expression of the trafficking-deficient, pathogenic KCNQ4 mutants L274H and W276S. KCNQ4 surface expression was restored by HSP90β in cells mimicking heterozygous conditions of the DFNA2 patients, even though it was

  20. 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

  1. Designing with null flux coils

    SciTech Connect

    Davey, K.R.

    1997-09-01

    Null flux were suggested by Danby and Powell in the late 1960`s as a useful means for realizing induced lift with little drag. As an array of alternating magnets is translated past a set of null flux coils, the currents induced in these coils act to vertically center the magnets on those coils. At present, one Japanese MAGLEV system company and two American-based companies are employing either null flux or flux eliminating coils in their design for high speed magnetically levitated transportation. The principle question addressed in paper is: what is the proper choice of coil length to magnet length in a null flux system? A generic analysis in the time and frequency domain is laid out with the intent of showing the optimal design specification in terms of coil parameters.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Molecular and functional characterization of TRPV4 channels in pregnant and nonpregnant mouse uterus.

    PubMed

    Singh, Vishakha; Ram, Mahendra; Kandasamy, Kannan; Thangamalai, Ramasamy; Choudhary, Soumen; Dash, Jeevan Ranjan; Kumar, Dhirendra; Parida, Subhashree; Singh, Thakur Uttam; Mishra, Santosh Kumar

    2015-02-01

    The aim of the present study was to characterize TRPV4 channels in pregnant and nonpregnant mouse uterus and examine their functional role in spontaneous and agonist-induced contractions. We used RT-PCR, Western blot and immunohistochemistry experiments to demonstrate the presence of TRPV4 mRNA and protein, respectively in both pregnant and nonpregnant mouse uterus. Tension experiments were conducted for functional characterization of the TRPV4 channels. TRPV4 mRNA and protein were detected in both pregnant and nonpregnant mouse uterus with distribution in both endometrium and myometrium. The TRPV4 channel agonist GSK1016790A (GSK) increased myometrial contraction in pregnant (Emax 336.8±21.35%; pD2 7.79±0.29) and nonpregnant (Emax 238±28.13%; pD2 7.61±0.57) animals. HC067047 (1μM), a selective blocker of the TRPV4 channel, antagonized the contractions to GSK in pregnant (Emax 171±18.26%; pD2 6.58±0.37) and nonpregnant (Emax 78.12±9.32%; pD2 7.54±0.9) uteri. Further, HC067047 (1μM) inhibited contractions induced by PGF2α in the pregnant (Emax 183.2±13.94%; pD2 7.01±0.30 versus control Emax 495.7±42.49%; pD2 7.12±0.24) and nonpregnant (Emax 105.3±7.10%; pD2 7.24±0.34 versus control Emax 232.5±12.27%; pD2 7.83±0.29) uteri. TRPV4 channels are present in the pregnant and nonpregnant mouse uteri, and their activation by endogenous ligands like prostaglandin increases myometrial contractility. Thus, the TRPV4 channel can be an important target in reducing myometrial contractility in preterm labor. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Microfiber coil resonator and waveguide

    NASA Astrophysics Data System (ADS)

    Sumetsky, Mikhail

    2005-04-01

    The recently suggested self-coupling microfiber coil optical resonator (COR) is a simplest functional element for the future microfiber-based photonics. It could be created by wrapping a microfiber on a dielectric rod with smaller refractive index. It is feasible that COR, which is produced from a drawn optical microfiber, will not suffer from surface roughness as e.g. the lithographically fabricated 2D microrings. Therefore, COR may have extremely small losses and generate high-Q resonances. In this paper, the theoretical study of the basic electromagnetic properties of the uniform self-coupling COR with N turns is presented. The eigenmodes of COR, which are qualitatively different from the modes of the known types of resonators, exist for the discrete values of the dimensionless coupling parameter K=κS > ½, where κ is the coupling coefficient between adjacent turns and S is the length of a turn. The spatial variation of the mode amplitudes does not have the wavelength scale oscillations and has no correlation with the period of COR, S. For certain series of K, the free spectrum range of COR is independent of the number of turns N and COR behaves similar to a single ring resonator. For N-->∞, the microfiber coil optical waveguide (COW) has a simple dispersion relation implying the absence of stop bands. The value K = ½ corresponds to the crossover between two regimes of propagation: with and without zeroing of the group velocity. At the crossover, the dispersion relation of COW has inflexion points wherein the group velocity and the inversed group velocity dispersion simultaneously become zero.

  9. 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.

  10. Heat transfer and flow in spiral channels and coils

    NASA Astrophysics Data System (ADS)

    Vilemas, J. V.; Poškas, P. S.

    1993-06-01

    An analysis of the experimental results for heat transfer on convex and concave walls of slotted spiral channels as well as for local heat transfer around the periphery and along the tube of the coils is presented. Great attention is paid to examining surface friction and its pulsations on the hydrodynamic entrance section and under stabilized coil flow conditions. The transition from laminar to turbulent flow on the convex and concave walls of slotted spiral channels and around the periphery of the tube of different-curvature coils is analyzed.

  11. Competition between Coiled-Coil Structures and the Impact on Myosin-10 Bundle Selection.

    PubMed

    Vavra, Kevin C; Xia, Youlin; Rock, Ronald S

    2016-06-07

    Coiled-coil fusions are a useful approach to enforce dimerization in protein engineering. However, the final structures of coiled-coil fusion proteins have received relatively little attention. Here, we determine the structural outcome of adjacent parallel and antiparallel coiled coils. The targets are coiled coils that stabilize myosin-10 in single-molecule biophysical studies. We reveal the solution structure of a short, antiparallel, myosin-10 coiled-coil fused to the parallel GCN4-p1 coiled coil. Surprisingly, this structure is a continuous, antiparallel coiled coil where GCN4-p1 pairs with myosin-10 rather than itself. We also show that longer myosin-10 segments in these parallel/antiparallel fusions are dynamic and do not fold cooperatively. Our data resolve conflicting results on myosin-10 selection of actin filament bundles, demonstrating the importance of understanding coiled-coil orientation and stability. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  12. 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.

  13. Numerical characterization of a flexible circular coil for magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Bautista, T.; Hernandez, R.; Solis-Najera, S. E.; Rodriguez, A. O.

    2012-10-01

    Numerical simulations of the magnetic field generated by a flexible surface coil were conducted to study its behavior for applications of animal models at 7 Tesla. This coil design is able to fully cover a volume of interest. The Finite Difference Method in Time Domain (FDTD) was used because of its ability to accurately model complex problems in electromagnetism. This particular coil design is best suited for regions of interests with a spherical shape, since B1 uniformity is not significantly attenuated as in the case of a circular-loop coil. It still remains to investigate the feasibility to actually construct a coil prototype.

  14. 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

  15. 10 Gbps transmission of electroabsorption modulators integrated with a 4-channel distributed Bragg reflector laser array

    NASA Astrophysics Data System (ADS)

    Ryu, Sang-Wan; Sim, Jae-Sik; Kwan, Yong-Hwan; Kim, Sung-Bock; Baek, Yong-Soon

    2008-05-01

    10 Gbps data transmission was demonstrated with electroabsorption modulators integrated with a 4-channel wavelength division multiplexing transmitter composed of distributed Bragg reflector (DBR) lasers. A selective area growth technique was employed for the control of bandgap energy in the gain, modulator and passive sections. Then the laser and modulator stripes were fabricated by a buried heterostructure process. The DBR lasers showed uniform threshold currents between 5 and 10 mA, while the slope efficiency was around 0.11 W A-1. By controlling the DBR currents, a 4-channel transmitter was achieved for the channel spacing of 100 GHz (0.8 nm). The electroabsorption modulator showed clear eye openings under 10 Gbps non-return-to-zero modulation. It allowed 10 Gbps error-free operation over a 25 km long single-mode fiber.

  16. Functional TRPV2 and TRPV4 channels in human cardiac c-kit(+) progenitor cells.

    PubMed

    Che, Hui; Xiao, Guo-Sheng; Sun, Hai-Ying; Wang, Yan; Li, Gui-Rong

    2016-06-01

    The cellular physiology and biology of human cardiac c-kit(+) progenitor cells has not been extensively characterized and remains an area of active research. This study investigates the functional expression of transient receptor potential vanilloid (TRPV) and possible roles for this ion channel in regulating proliferation and migration of human cardiac c-kit(+) progenitor cells. We found that genes coding for TRPV2 and TRPV4 channels and their proteins are significantly expressed in human c-kit(+) cardiac stem cells. Probenecid, an activator of TRPV2, induced an increase in intracellular Ca(2+) (Ca(2+) i ), an effect that may be attenuated or abolished by the TRPV2 blocker ruthenium red. The TRPV4 channel activator 4α-phorbol 12-13-dicaprinate induced Ca(2+) i oscillations, which can be inhibited by the TRPV4 blocker RN-1734. The alteration of Ca(2+) i by probenecid or 4α-phorbol 12-13-dicprinate was dramatically inhibited in cells infected with TRPV2 short hairpin RNA (shRNA) or TRPV4 shRNA. Silencing TRPV2, but not TRPV4, significantly reduced cell proliferation by arresting cells at the G0/G1 boundary of the cell cycle. Cell migration was reduced by silencing TRPV2 or TRPV4. Western blot revealed that silencing TRPV2 decreased expression of cyclin D1, cyclin E, pERK1/2 and pAkt, whereas silencing TRPV4 only reduced pAkt expression. Our results demonstrate for the first time that functional TRPV2 and TRPV4 channels are abundantly expressed in human cardiac c-kit(+) progenitor cells. TRPV2 channels, but not TRPV4 channels, participate in regulating cell cycle progression; moreover, both TRPV2 and TRPV4 are involved in migration of human cardiac c-kit(+) progenitor cells. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  17. TRPV4 Channels Contribute to Renal Myogenic Autoregulation in Neonatal Pigs.

    PubMed

    Soni, Hitesh; Peixoto-Neves, Dieniffer; Matthews, Anberitha T; Adebiyi, Adebowale

    2017-08-02

    Myogenic response, a phenomenon in which resistance size arteries and arterioles swiftly constrict or dilate in response to an acute elevation or reduction, respectively in intravascular pressure is a key component of renal autoregulation mechanisms. Although it is well-established that the renal system is functionally immature in neonates, mechanisms that regulate neonatal renal blood flow (RBF) remain poorly understood. In this study, we investigated the hypothesis that members of the transient receptor potential vanilloid (TRPV) channels are molecular components of renal myogenic constriction in newborns. We show that unlike TRPV1-3, TRPV4 channels are predominantly expressed in neonatal pig preglomerular vascular smooth muscle cells (SMCs). Intracellular Ca(2+) ([Ca(2+)]i) elevation induced by osmotic cell swelling was attenuated by TRPV4, L-type Ca(2+), and stretch-activated Ca(2+) channel blockers, but not phospholipase A2 inhibitor. Blockade of TRPV4 channels reversed steady-state myogenic tone and inhibited pressure-induced membrane depolarization, [Ca(2+)]i elevation, and constriction in distal interlobular arteries. A step increase in arterial pressure induced efficient autoregulation of renal cortical perfusion and total RBF in anesthetized and mechanically ventilated neonatal pigs. Moreover, intrarenal arterial infusion of TRPV4 channel blockers HC 067047 and RN 1734 attenuated renal autoregulation in the pigs. These data suggest that renal myogenic autoregulation is functional in neonates. Our findings also indicate that TRPV4 channels are mechanosensors in neonatal pig preglomerular vascular SMCs, and contribute to renal myogenic autoregulation. Copyright © 2017, American Journal of Physiology-Renal Physiology.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

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

    PubMed

    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.

  9. 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)

  10. Pickup coil optimization for polarized 3He system

    NASA Astrophysics Data System (ADS)

    Tu, X. Q.; Zheng, H.; Sun, G. A.; Gong, J.; Ren, Y.; Liu, L. J.; Gao, P. L.; Wang, W. Z.; Yan, H.

    2017-07-01

    Not only can polarized 3He gas work as neutron spin filters (NSF) but also search for spin-dependent new interactions beyond the standard model. For both cases, the relative polarization of the spin polarized noble gas needs to be measured precisely. Various NMR techniques are applied practically to monitor the 3He cell's polarization. In this work, we tried to optimize the pickup coil for the spin exchange optical pump (SEOP) based 3He system. By optimizing the signal-to-noise ratio (SNR), we found that the coil should be wound by thin wire for a higher number of turns. The optimized sizes of the pickup coils depend on the detailed configurations. For a spherical 3He cell with radius a, we found the optimized coil radius is √{5}(a+d), where d is the coil to cell surface distance. For a cylindrical 3He cell with height h, for the configurations where the coils were placed either along or perpendicular to the longitudinal axis of the target cell, we derived the optimized sizes for the specific configurations. We believe these results are practically useful for designing pickup coils of polarized 3He systems.

  11. 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.

  12. Immunogenicity of coiled-coil based drug-free macromolecular therapeutics

    PubMed Central

    Kverka, Miloslav; Hartley, Jonathan M.; Chu, Te-Wei; Yang, Jiyuan; Heidchen, Regina; Kopeček, Jindřich

    2014-01-01

    A two-component CD20 (non-internalizing) receptor crosslinking system based on the biorecognition of complementary coiled-coil forming peptides was evaluated. Exposure of B cells to Fab’-peptide1 conjugate decorates the cell surface with peptide1; further exposure of the decorated cells to P-(peptide2)x (P is the N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer backbone) results in the formation of coiled-coil heterodimers at the cell surface with concomitant induction of apoptosis. The aim of this study was to determine the potential immunogenicity of this therapeutic system that does not contain low molecular weight drugs. Enantiomeric peptides (L- and D-CCE and L- and D-CCK), HPMA copolymer-peptide conjugates, and Fab’ fragment-peptide conjugates were synthesized and the immunological properties of peptide conjugates evaluated in vitro on RAW264.7 macrophages and in vivo on immunocompetent BALB/c mice. HPMA copolymer did not induce immune response in vitro and in vivo. Administration of P-peptide conjugates with strong adjuvant resulted in antibody response directed to the peptide. Fab’ was responsible for macrophage activation of Fab’-peptide conjugates and a major factor in the antibody induction following i.v. administration of Fab’ conjugates. There was no substantial difference in the ability of conjugates of D-peptides and conjugates of L-peptides to induce Ab response. PMID:24767787

  13. Actively Decoupled Transmit-Receive Coil-Pair for Mouse Brain MRI.

    PubMed

    Garbow, Joel R; McIntosh, Charlie; Conradi, Mark S

    2008-10-01

    A low-cost, high performance RF coil-pair for MR imaging of mouse brain is described. A surface receiving coil is used for high spin-sensitivity, while a larger transmit coil, located outside the mouse holder, delivers good B1 uniformity across the brain with reasonable efficiency. The volume coil is constructed with an open architecture, making experimental setup easy and providing clear access to the head of the mouse. Each coil is switched between active and inactive modes using PIN diodes driven by a small amplifier external to the spectrometer. Because of this active decoupling, there is no requirement for orthogonal orientation of the coils. The coil pair is platform independent, requiring only a transmit/receive (T/R) signal to switch the amplifier that drives the PIN diodes, and can therefore be used with virtually any commercial or home-built MR scanner.

  14. Efficient high-frequency body coil for high-field MRI.

    PubMed

    Vaughan, J T; Adriany, G; Snyder, C J; Tian, J; Thiel, T; Bolinger, L; Liu, H; DelaBarre, L; Ugurbil, K

    2004-10-01

    The use of body coils is favored for homogeneous excitation, and such coils are often paired with surface coils or arrays for sensitive reception in many MRI applications. While the body coil's physical size and resultant electrical length make this circuit difficult to design for any field strength, recent efforts to build efficient body coils for applications at 3T and above have been especially challenging. To meet this challenge, we developed an efficient new transverse electromagnetic (TEM) body coil and demonstrated its use in human studies at field strengths up to 4 T. Head, body, and breast images were acquired within peak power constraints of <8 kW. Bench studies indicate that these body coils are feasible to 8 T. RF shimming was used to remove a high-field-related cardiac imaging artifact in these preliminary studies. P41RR13230

  15. 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.

  16. 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.

  17. The evolution and structure prediction of coiled coils across all genomes.

    PubMed

    Rackham, Owen J L; Madera, Martin; Armstrong, Craig T; Vincent, Thomas L; Woolfson, Derek N; Gough, Julian

    2010-10-29

    Coiled coils are α-helical interactions found in many natural proteins. Various sequence-based coiled-coil predictors are available, but key issues remain: oligomeric state and protein-protein interface prediction and extension to all genomes. We present SpiriCoil (http://supfam.org/SUPERFAMILY/spiricoil), which is based on a novel approach to the coiled-coil prediction problem for coiled coils that fall into known superfamilies: hundreds of hidden Markov models representing coiled-coil-containing domain families. Using whole domains gives the advantage that sequences flanking the coiled coils help. SpiriCoil performs at least as well as existing methods at detecting coiled coils and significantly advances the state of the art for oligomer state prediction. SpiriCoil has been run on over 16 million sequences, including all completely sequenced genomes (more than 1200), and a resulting Web interface supplies data downloads, alignments, scores, oligomeric state classifications, three-dimensional homology models and visualisation. This has allowed, for the first time, a genomewide analysis of coiled-coil evolution. We found that coiled coils have arisen independently de novo well over a hundred times, and these are observed in 16 different oligomeric states. Coiled coils in almost all oligomeric states were present in the last universal common ancestor of life. The vast majority of occasions that individual coiled coils have arisen de novo were before the last universal common ancestor of life; we do, however, observe scattered instances throughout subsequent evolutionary history, mostly in the formation of the eukaryote superkingdom. Coiled coils do not change their oligomeric state over evolution and did not evolve from the rearrangement of existing helices in proteins; coiled coils were forged in unison with the fold of the whole protein. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Design considerations in coiled-coil fusion constructs for the structural determination of a problematic region of the human cardiac myosin rod.

    PubMed

    Andreas, Michael P; Ajay, Gautam; Gellings, Jaclyn A; Rayment, Ivan

    2017-07-22

    X-ray structural determination of segments of the myosin rod has proved difficult because of the strong salt-dependent aggregation properties and repeating pattern of charges on the surface of the coiled-coil that lead to the formation of paracrystals. This problem has been resolved in part through the use of globular assembly domains that improve protein folding and prevent aggregation. The primary consideration now in designing coiled-coil fusion constructs for myosin is deciding where to truncate the coiled-coil and which amino acid residues to include from the folding domain. This is especially important for myosin that contains numerous regions of low predicted coiled-coil propensity. Here we describe the strategy adopted to determine the structure of the region that extends from Arg1677 - Leu1797 that included two areas that do not show a strong sequence signature of a conventional left-handed coiled coil or canonical heptad repeat. This demonstrates again that, with careful choice of fusion constructs, overlapping structures exhibit very similar conformations for the myosin rod fragments in the canonical regions. However, conformational variability is seen around Leu1706 which is a hot spot for cardiomyopathy mutations suggesting that this might be important for function. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Impact of magnetic field strength and receiver coil in ocular MRI: a phantom and patient study.

    PubMed

    Erb-Eigner, K; Warmuth, C; Taupitz, M; Willerding, G; Bertelmann, E; Asbach, P

    2013-09-01

    Generally, high-resolution MRI of the eye is performed with small loop surface coils. The purpose of this phantom and patient study was to investigate the influence of magnetic field strength and receiver coils on image quality in ocular MRI. The eyeball and the complex geometry of the facial bone were simulated by a skull phantom with swine eyes. MR images were acquired with two small loop surface coils with diameters of 4 cm and 7 cm and with a multi-channel head coil at 1.5 and 3 Tesla, respectively. Furthermore, MRI of the eye was performed prospectively in 20 patients at 1.5 Tesla (7 cm loop surface coil) and 3 Tesla (head coil). These images were analysed qualitatively and quantitatively and statistical significance was tested using the Wilcoxon-signed-rank test (a p-value of less than 0.05 was considered to indicate statistical significance). The analysis of the phantom images yielded the highest mean signal-to-noise ratio (SNR) at 3 Tesla with the use of the 4 cm loop surface coil. In the phantom experiment as well as in the patient studies the SNR was higher at 1.5 Tesla by applying the 7 cm surface coil than at 3 Tesla by applying the head coil. Concerning the delineation of anatomic structures no statistically significant differences were found. Our results show that the influence of small loop surface coils on image quality (expressed in SNR) in ocular MRI is higher than the influence of the magnetic field strength. The similar visibility of detailed anatomy leads to the conclusion that the image quality of ocular MRI at 3 Tesla remains acceptable by applying the head coil as a receiver coil. © Georg Thieme Verlag KG Stuttgart · New York.

  20. 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.

  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. Magnetic resonance imaging receiver coil decoupling using circumferential shielding structures.

    PubMed

    Yeh, Jhy-Neng Tasso; Fa-Hsuan Lin

    2016-08-01

    We propose a flexible phased-array design using circular coils with circumferential shielding structure to achieve robust decoupling between coil elements when the array is either bended or on a flat plane. Two types of circumferential shielding were tested through numerical simulation and imaging experiment. The results demonstrated that our arrays have good decoupling between coils when they are on a curved surface with S21 <; -16.72 dB. Both types perform higher SNR images than a commercially available 32-channel adult head coil array. Future work will empirically construct a multi-channel array with the number of channel matched to commercial phased array in order to validate the performance in vivo.

  3. 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.

  4. 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.

  5. Synthesis and functionalization of coiled carbon filaments

    NASA Astrophysics Data System (ADS)

    Hikita, Muneaki

    grown at the higher temperature had smaller fiber size and coil diameter, and longer lifetime of catalyst. For in-depth analysis, growth kinetics of CMCs were studied using an exponential decay model for catalyst poisoning. In the third study, CMCs were functionalized for improvement of water dispersion, optical properties and self-assembly. As-grown CMCs were hydrophobic. To improve water dispersion for biological applications, the surface of as-grown CMCs were oxidized by concentrated nitric acid at room temperature. After the oxidation, the acid-treated CMCs were well dispersed in water. For optical property, CMCs were functionalized with octadecylamine (ODA). Upon photoexcitation, the functionalized CMCs exhibited photoluminescence in the visible region. Similar to carbon based nanoparticles, the photoluminescence of CMCs was attributed to electron-hole radiative recombination after surface passivation. The results suggest that these functionalized CMCs might be used as a new class of optical agents for biological applications. As a primary experiment to study Au-S bonding, aminoethanethiol (HSCH2CH2NH2) was attached to the surface of gold-coated CMCs. Energy dispersive X-ray (EDX) mapping shows gold, sulfur and nitrogen on the surface of CMCs. Then, a thiol-modified ssDNA attachment experiment was performed using a similar functionalization procedure as aminoethanethiol. The existence of phosphorus, nitrogen, oxygen and sulfur on surface of Au-coated CMCs immersed in thiol-modified ssDNA solution was confirmed by the EDX spectrum. The result indicates that ssDNA was fixed on their surface. In the fourth study, the effect of oxidized CMCs on mouse embryonic stem (MES) cells was examined to determine their toxicity. Mouse embryonic stem cells represent a unique cell population with the ability to undergo both self-renewal and differentiation. Results indicate that oxidized CMCs had very little toxicity on stem cell viability. There was no observed loss of alkaline

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. External-cavity beam combining of 4-channel quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Zhang, Jin-Chuan; Zhou, Yu-Hong; Jia, Zhi-Wei; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

    2017-09-01

    We demonstrate an external-cavity (EC) beam combining of 4-channel quantum cascade lasers (QCLs) with an output coupler which makes different QCL beams propagating coaxially. A beam combining efficiency of 35% (up to 75% near threshold) is obtained with a beam quality M2 of 5.5. A peak power of 0.64 W is achieved at a wavelength of 4.7 μm. The differences of spot characteristic between coupled and uncoupled are also showed in this letter. The QCLs in this EC system do not have heat crosstalk so that the system can be used for high power beam combining of QCLs.

  11. High-resolution structures of a heterochiral coiled coil

    DOE PAGES

    Mortenson, David E.; Steinkruger, Jay D.; Kreitler, Dale F.; ...

    2015-10-12

    Interactions between polypeptide chains containing amino acid residues with opposite absolute configurations have long been a source of interest and speculation, but there is very little structural information for such heterochiral associations. The need to address this lacuna has grown in recent years because of increasing interest in the use of peptides generated from D amino acids (D peptides) as specific ligands for natural proteins, e.g., to inhibit deleterious protein–protein interactions. Coiled–coil interactions, between or among α-helices, represent the most common tertiary and quaternary packing motif in proteins. Heterochiral coiled–coil interactions were predicted over 50 years ago by Crick, andmore » limited experimental data obtained in solution suggest that such interactions can indeed occur. To address the dearth of atomic-level structural characterization of heterochiral helix pairings, we report in this paper two independent crystal structures that elucidate coiled-coil packing between L- and D-peptide helices. Both structures resulted from racemic crystallization of a peptide corresponding to the transmembrane segment of the influenza M2 protein. Networks of canonical knobs-into-holes side-chain packing interactions are observed at each helical interface. Finally, however, the underlying patterns for these heterochiral coiled coils seem to deviate from the heptad sequence repeat that is characteristic of most homochiral analogs, with an apparent preference for a hendecad repeat pattern.« less

  12. Hydrophobic core packing and backbone flexibility in coiled coils

    NASA Astrophysics Data System (ADS)

    Plecs, Joseph John

    1999-11-01

    An understanding of the structure and function of protein molecules requires an understanding of how their hydrophobic cores are assembled, including how the peptide backbone can adjust to accommodate different packing arrangements. Using coiled-coil molecules as a model of protein structures, we studied several cases in which the arrangement of packing groups in the hydrophobic core controls the structure of a folded molecule. First, we consider an example of a prosthetic packing group, where the addition of a hydrophobic ligand permits a new packing arrangement that incorporates the ligand, leading to a new overall structure. Second, the crystal structures of two peptides designed to adopt a novel fold, the right-handed coiled coils, reveal how a small change in core packing can discriminate between two different folds. And last, the design of heterodimers based on core-packing complementarity establishes that core packing can convey specificity of association between different molecules, as well as determining the molecular structure. The heterodimer designs also demonstrate the importance of a combination of backbone freedom and restriction in predicting the energetics of folded molecules. In this case, a parametrized coiled- coil backbone with appropriate parameters and restrictions was required to predict stabilities. We conclude that core packing can exert a great deal of control over the structure of proteins, and that many of its effects can be accurately predicted by modeling the molecular interactions in the context of a flexible overall structure.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Depletion-Mode GaN HEMT Q-Spoil Switches for MRI Coils.

    PubMed

    Lu, Jonathan Y; Grafendorfer, Thomas; Zhang, Tao; Vasanawala, Shreyas; Robb, Fraser; Pauly, John M; Scott, Greig C

    2016-12-01

    Q-spoiling is the process of decoupling an MRI receive coil to protect the equipment and patient. Conventionally, Q-spoiling is performed using a PIN diode switch that draws significant current. In this work, a Q-spoiling technique using a depletion-mode Gallium Nitride HEMT device was developed for coil detuning at both 1.5 T and 3 T MRI. The circuits with conventional PIN diode Q-spoiling and the GaN HEMT device were implemented on surface coils. SNR was measured and compared for all surfaces coils. At both 1.5 T and 3 T, comparable SNR was achieved for all coils with the proposed technique and conventional Q-spoiling. The GaN HEMT device has significantly reduced the required power for Q-spoiling. The GaN HEMT device also provides useful safety features by detuning the coil when unpowered.

  1. 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.

  2. 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.

  3. 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).

  4. 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.

  5. 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.

  6. Opposing actions of TRPV4 channel activation in the lung vasculature.

    PubMed

    Ke, Sun-Kui; Chen, Lan; Duan, Hong-Bing; Tu, Yuan-Rong

    2015-12-01

    Transient receptor potential vanilloid 4 (TRPV4) calcium channels are known to promote endothelium-dependent relaxation of mouse mesenteric arteries but TRPV4's role in the pulmonary vasculature is uncertain. Thus, we characterized TRPV4 channel vascular tone regulation in mouse main pulmonary artery rings and in the isolated perfused pulmonary circulation and studied possible mechanisms behind these characterizations. Using myography and a TRPV4 specific agonist GSK1016790A in a C57BL/6 WT mouse model of isolated constant-flow lung perfusion, we studied vascular tone regulation in arterial rings from the main left and right pulmonary arteries and vascular resistance of the intra-pulmonary circulation beyond the second branches of the pulmonary arteries. Removal of the endothelium confirmed endothelial dependence. GSK1016790A relaxed the main pulmonary artery (EC50 4 × 10(-8)mol/L), which was inhibited by removal of the endothelium from main pulmonary artery rings. GSK1016790A significantly increased vascular resistance of the pulmonary circulation in isolated perfused lungs, but these effects were inhibited by a TRPV4 antagonist AB159908. A nitric oxide inhibitor NG-nitro-L-arginine methyl ester (L-NAME) and K(+) channel blockers apamin plus charybdotoxin (ChTx) significantly inhibited GSK1016790A in the main pulmonary artery and in an isolated perfused lung in vitro. Activated TRPV4 channels increase pulmonary vascular resistance and vasodilate the main pulmonary artery. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. 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.

  8. Berberine via suppression of transient receptor potential vanilloid 4 channel improves vascular stiffness in mice.

    PubMed

    Wang, Jie; Guo, Tao; Peng, Qi-Sheng; Yue, Shou-Wei; Wang, Shuang-Xi

    2015-11-01

    Berberine, as an alkaloid found in many Chinese herbs, improves vascular functions in patients with cardiovascular diseases. We determined the effects of berberine in hypertension and vascular ageing, and elucidated the underlying mechanisms. In isolated aortas, berberine dose-dependently elicited aortic relaxation. In cultured cells, berberine induced the relaxation of vascular smooth muscle cells (VSMCs). Overexpression of transient receptor potential vanilloid 4 (TRPV4) channel by genetic approaches abolished the berberine-induced reduction in intracellular Ca(2+) concentration in VSMCs and attenuated berberine-elicited vessel dilation in mice aortas. In deoxycorticosterone acetate (DOCA)-induced hypertensive model, treatment of mice with berberine or RN-1734, a pharmacological inhibitor of TRPV4, significantly decreased systemic blood pressure (BP) in control mice or mice infected with an adenovirus vector. However, berberine-induced effects of lowering BP were reversed by overexpressing TRPV4 in mice by infecting with adenovirus. Furthermore, long-term administration of berberine decreased mean BP and pulse BP, increased artery response to vasodilator and reduced vascular collagen content in aged mice deficient in apolipoprotein E (Apoe-KO), but not in Apoe-KO old mice with lentivirus-mediated overexpression of TRPV4 channel. In conclusion, berberine induces direct vasorelaxation to lower BP and reduces vascular stiffness in aged mice through suppression of TRPV4. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  9. 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.

  10. 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.

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

    PubMed

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

    2016-09-22

    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 Ca(2+) signaling, integrity and endothelium-dependent vasodilation. These results suggest that TRPV4 antagonists may be of therapeutic utility in the management of sepsis.

  12. 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.

  13. Dynamic multi-channel TMS with reconfigurable coil.

    PubMed

    Jiang, Ruoli; Jansen, Ben H; Sheth, Bhavin R; Chen, Ji

    2013-05-01

    Investigations of the causal involvement of particular brain areas and interconnections in behavior require an external stimulation system with reasonable spatio-temporal resolution. Current transcranial magnetic stimulation (TMS) technology is limited to stimulating a single brain area once in a given trial. Here, we present a feasibility study for a novel TMS system based on multi-channel reconfigurable coils. With this hardware, researchers will be able to stimulate multiple brain sites in any temporal order in a trial. The system employs a wire-mesh coil, constructed using x- and y-directional wires. By varying the current direction and/or strength on each wire, we can configure the proposed mesh-wire coil into a standard loop coil and figure-eight coil of varying size. This provides maximum flexibility to the experimenter in that the location and extent of stimulation on the brain surface can be modified depending on experimental requirement. Moreover, one can dynamically and automatically modify the site(s) of stimulation several times within the span of seconds. By pre-storing various sequences of excitation patterns inside a control unit, one can explore the effect of dynamic TMS on behavior, in associative learning, and as rehabilitative therapy. Here, we present a computer simulation and bench experiments that show the feasibility of the dynamically-reconfigurable coil.

  14. AKAP150-dependent cooperative TRPV4 channel gating is central to endothelium-dependent vasodilation and is disrupted in hypertension

    PubMed Central

    Sonkusare, Swapnil K.; Dalsgaard, Thomas; Bonev, Adrian D.; Hill-Eubanks, David C.; Kotlikoff, Michael I.; Scott, John D.; Santana, Luis F.; Nelson, Mark T.

    2015-01-01

    Endothelial cell dysfunction, characterized by a diminished response to endothelial cell–dependent vasodilators, is a hallmark of hypertension. TRPV4 channels play a major role in endothelial-dependent vaso-dilation, a function mediated by local Ca2+ influx through clusters of functionally coupled TRPV4 channels rather than by a global increase in endothelial cell Ca2+. We showed that stimulation of muscarinic acetylcholine receptors on endothelial cells of mouse arteries exclusively activated TRPV4 channels that were localized at myoendothelial projections (MEPs), specialized regions of endothelial cells that contact smooth muscle cells. Muscarinic receptor–mediated activation of TRPV4 depended on protein kinase C (PKC) and the PKC-anchoring protein AKAP150, which was concentrated at MEPs. Cooperative opening of clustered TRPV4 channels specifically amplified Ca2+ influx at MEPs. Cooperativity of TRPV4 channels at non-MEP sites was much lower, and cooperativity at MEPs was greatly reduced by chelation of intracellular Ca2+ or AKAP150 knockout, suggesting that Ca2+ entering through adjacent channels underlies the AKAP150-dependent potentiation of TRPV4 activity. In a mouse model of angiotensin II–induced hypertension, MEP localization of AKAP150 was disrupted, muscarinic receptor stimulation did not activate TRPV4 channels, cooperativity among TRPV4 channels at MEPs was weaker, and vasodilation in response to muscarinic receptor stimulation was reduced. Thus, endothelial-dependent dilation of resistance arteries is enabled by MEP-localized AKAP150, which ensures the proximity of PKC to TRPV4 channels and the coupled channel gating necessary for efficient communication from endothelial to smooth muscle cells in arteries. Disruption of this molecular assembly may contribute to altered blood flow in hypertension. PMID:25005230

  15. 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.

  16. Dental MRI using a dedicated RF-coil at 3 Tesla.

    PubMed

    Prager, Marcel; Heiland, Sabine; Gareis, Daniel; Hilgenfeld, Tim; Bendszus, Martin; Gaudino, Chiara

    2015-12-01

    To assess the benefit of a dedicated surface coil to visualize dental structures in comparison to standard head/neck coil. Measurements were performed using the standard head/neck coil and a dedicated array coil for dental MRI at 3 T. As MRI methods, we used a T1-weighted spin-echo sequence with and without spectral fat saturation, a T2-weighted turbo-spin-echo sequence and a 3-dimensional T2-weighted SPACE sequence. Measurements were performed in a phantom to examine sensitivity profiles. Then the signal gain in dental structures was examined in volunteers and in a patient. As expected for a surface coil, the signal gain of the dental coil was highest at the surface of the phantom and decreased with increasing distance to the coil; it was >120% even at a depth of 30 mm, measured from the centre of the coil. The signal gain within the pulp of the volunteers ranged between 236 and 413%. The dedicated array coil offers a significantly higher signal within the region of interest for dental MR imaging thus allowing for better depiction of pathologies within the periodontium and for delineation and tracking of the branches of the maxillary and mandibular nerves. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2016-01-01

    To design, construct and validate radiofrequency (RF) transmit and receive phased array coils for high-resolution visual cortex imaging at 7 Tesla. 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 [Formula: see text] 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. 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. 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.

  18. 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.

  19. 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.

  20. Improvement of SNR and acquisition acceleration using a 32-channel head coil compared to a 12-channel head coil at 3T.

    PubMed

    Reiss-Zimmermann, Martin; Gutberlet, Marcel; Köstler, Herbert; Fritzsch, Dominik; Hoffmann, Karl-Titus

    2013-07-01

    Magnetic resonance imaging (MRI) techniques continue to improve in manifold ways. Besides field strength and sequence optimization, technical advances in coil design and sensitivity yield to increase the signal detection and therefore improve image quality. To evaluate the performance of signal-to-noise ratio (SNR) and parallel acquisition technique (PAT) acceleration of a dedicated 32-channel head coil compared with a standard 12-channel head coil. In a clinical 3T setting, spatial resolved SNR values for unaccelerated imaging and PAT with acceleration factors of 2-6 of a 32-channel head coil were evaluated in relation to a 12-channel head coil. SNR was determined quantitatively using proton-density-weighted in-vivo examinations in five healthy volunteers. Quantitative SNR maps for unaccelerated and PAT imaging were calculated using unfiltered MR raw data. Up to three-fold higher SNR values were achieved with the 32-channel head coil, which diminished towards the center to an increase of 40% compared with the 12-channel head coil. When using PAT, the 32-channel head coil resulted in a lower spatial-dependent quantitative noise enhancement, varying between 0% at R = 2 and 33% at R = 5. The 32-channel head coil provided superior SNR both with and without PAT compared with a 12-channel head coil, especially close to the brain surface. Using PAT, the unavoidable noise enhancement is diminished up to acceleration factors of 6 for the 32-channel head coil. Therefore, the 32-channel head coil is considered as a preferable tool for high-resolution neuroradiological imaging.

  1. Hydrogen sulfide-induced vasodilation mediated by endothelial TRPV4 channels.

    PubMed

    Naik, Jay S; Osmond, Jessica M; Walker, Benjimen R; Kanagy, Nancy L

    2016-12-01

    Hydrogen sulfide (H2S) is a recently described gaseous vasodilator produced within the vasculature by the enzymes cystathionine γ-lyase and 3-mercaptopyruvate sulfurtransferase. Previous data demonstrate that endothelial cells (EC) are the source of endogenous H2S production and are required for H2S-induced dilation. However, the signal transduction pathway activated by H2S within EC has not been elucidated. TRPV4 and large-conductance Ca(2+)-activated K channels (BK channels) are expressed in EC. H2S-induced dilation is inhibited by luminal administration of iberiotoxin and disruption of the endothelium. Calcium influx through TRPV4 may activate these endothelial BK channels (eBK). We hypothesized that H2S-mediated vasodilation involves activation of TRPV4 within the endothelium. In pressurized, phenylephrine-constricted mesenteric arteries, H2S elicited a dose-dependent vasodilation blocked by inhibition of TRPV4 channels (GSK2193874A, 300 nM). H2S (1 μM) increased TRPV4-dependent (1.8-fold) localized calcium events in EC of pressurized arteries loaded with fluo-4 and Oregon Green. In pressurized EC tubes, H2S (1 μM) and the TRPV4 activator, GSK101679A (30 nM), increased calcium events 1.8- and 1.5-fold, respectively. H2S-induced an iberiotoxin-sensitive outward current measured using whole cell patch-clamp techniques in freshly dispersed EC. H2S increased K(+) currents from 10 to 30 pA/pF at +150 mV. Treatment with Na2S increased the level of sulfhydration of TRPV4 channels in aortic ECs. These results demonstrate that H2S-mediated vasodilation involves activation of TRPV4-dependent Ca(2+) influx and BK channel activation within EC. Activation of TRPV4 channels appears to cause calcium events that result in the opening of eBK channels, endothelial hyperpolarization, and subsequent vasodilation. Copyright © 2016 the American Physiological Society.

  2. 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

  3. Single-molecule observation of helix staggering, sliding, and coiled coil misfolding

    PubMed Central

    Xi, Zhiqun; Gao, Ying; Sirinakis, George; Guo, Honglian; Zhang, Yongli

    2012-01-01

    The biological functions of coiled coils generally depend on efficient folding and perfect pairing of their α-helices. Dynamic changes in the helical registry that lead to staggered helices have only been proposed for a few special systems and not found in generic coiled coils. Here, we report our observations of multiple staggered helical structures of two canonical coiled coils. The partially folded structures are formed predominantly by coiled coil misfolding and occasionally by helix sliding. Using high-resolution optical tweezers, we characterized their energies and transition kinetics at a single-molecule level. The staggered states occur less than 2% of the time and about 0.1% of the time at zero force. We conclude that dynamic changes in helical registry may be a general property of coiled coils. Our findings should have broad and unique implications in functions and dysfunctions of proteins containing coiled coils. PMID:22451899

  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. 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.

  6. 4 channels x 10-Gbps optoelectronic transceiver based on silicon optical bench technology

    NASA Astrophysics Data System (ADS)

    Chen, Chin T.; Hsiao, Hsu L.; Chang, Chia. C.; Shen, Po K.; Lu, Guan F.; Lee, Yun C.; Chang, Shou F.; Lin, Yo S.; Wu, Mount L.

    2012-01-01

    In this paper, a bi-directional 4-channel x 10-Gbps optoelectronic transceiver based on this silicon optical bench (SiOB) technology is developed. A bi-directional optical sub-assembly (BOSA), fiber ribbon assembly, PCB with high frequency trace design, transmitter driver, and receiver TIA IC are included in this transceiver. The BOSA and PCB also have some specific design for conventional chip-on-board (COB) process. In eye diagram measurement, the transmitter can pass 10-G Ethernet eye mask with 25% margin at room temperature; Bit-error-rate (BER) performance from the transmitter to receiver via 10-meter fiber can achieve 10-12 order, which confirm the transceiver's ability of 10-Gbps data transmission per a channel.

  7. Identification of the Molecular Site of Ivabradine Binding to HCN4 Channels

    PubMed Central

    Nardini, Marco; Barbuti, Andrea; Micheloni, Stefano; Bolognesi, Martino; DiFrancesco, Dario

    2013-01-01

    Ivabradine is a specific heart rate-reducing agent approved as a treatment of chronic stable angina. Its mode of action involves a selective and specific block of HCN channels, the molecular components of sinoatrial "funny" (f)-channels. Different studies suggest that the binding site of ivabradine is located in the inner vestibule of HCN channels, but the molecular details of ivabradine binding are unknown. We thus sought to investigate by mutagenesis and in silico analysis which residues of the HCN4 channel, the HCN isoform expressed in the sinoatrial node, are involved in the binding of ivabradine. Using homology modeling, we verified the presence of an inner cavity below the channel pore and identified residues lining the cavity; these residues were replaced with alanine (or valine) either alone or in combination, and WT and mutant channels were expressed in HEK293 cells. Comparison of the block efficiency of mutant vs WT channels, measured by patch-clamp, revealed that residues Y506, F509 and I510 are involved in ivabradine binding. For each mutant channel, docking simulations correctly explain the reduced block efficiency in terms of proportionally reduced affinity for ivabradine binding. In summary our study shows that ivabradine occupies a cavity below the channel pore, and identifies specific residues facing this cavity that interact and stabilize the ivabradine molecule. This study provides an interpretation of known properties of f/HCN4 channel block by ivabradine such as the “open channel block”, the current-dependence of block and the property of "trapping" of drug molecules in the closed configuration. PMID:23308150

  8. Fluid-induced lung injury-role of TRPV4 channels.

    PubMed

    Bihari, Shailesh; Dixon, Dani-Louise; Lawrence, Mark D; De Bellis, Dylan; Bonder, Claudine S; Dimasi, David P; Bersten, Andrew D

    2017-04-29

    Administration of bolus intravenous fluid is associated with respiratory dysfunction and increased mortality, findings with no clear mechanistic explanation. The objective of this study was to examine whether bolus intravenous (i.v.) fluid administration results in acute lung injury in a rat model and further, to examine whether this injury is associated with transient receptor potential vallinoid (TRPV)4 channel function and endothelial inflammatory response. Healthy male Sprague-Dawley rats were administered 60 ml/kg 0.9% saline i.v. over 30 min. Manifestation of acute lung injury was assessed by lung physiology, morphology, and markers of inflammation. The role of TRPV4 channels in fluid-induced lung injury was subsequently examined by the administration of ruthenium red (RR) in this established rat model and again in TRPV4 KO mice. In endothelial cell culture, permeability and P-selectin expression were measured following TRPV4 agonist with and without antagonist; 0.9% saline resulted in an increase in lung water, lavage protein and phospholipase A2, and plasma angiopoietin-2, with worsening in arterial blood oxygen (PaO2), lung elastance, surfactant activity, and lung histological injury score. These effects were ameliorated following i.v. fluid in rats receiving RR. TRPV4 KO mice did not develop lung edema. Expression of P-selectin increased in endothelial cells following administration of a TRPV4 agonist, which was ameliorated by simultaneous addition of RR. Bolus i.v. 0.9% saline resulted in permeability pulmonary edema. Data from ruthenium red, TRPV4 KO mice, and endothelial cell culture suggest activation of TRPV4 and release of angiopoietin 2 and P-selectin as the central mechanism.

  9. 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.

  10. 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.

  11. Using the Genetic Algorithm to Find Coils for Compact Stellarators

    NASA Astrophysics Data System (ADS)

    Miner, , Jr.; Valanju, P. M.; Hirshman, S. P.; Brooks, A.; Pomphrey, N.

    1999-11-01

    Stellarators are now optimized by finding the shape of the plasma surface that produces a desired mix of physics properties. The challenge is to find a practical coil set that creates that optimized surface with sufficient accuracy to retain the desired physics properties and still meet engineering and experimental constraints. Given the wide range of possible coil geometries, this is a daunting task requiring iterations between a practical coil geometry and the physics properties produced by it. A novel technique, the Genetic Algorithm (GA) (D.E. Goldberg, Genetic Algorithms in Search, Optimization, and Machine Leaning), (Addison Wesley, New York) 1989., has recently been applied to this problem. The GA is a computational search procedure for finding the global minimum of a target function using natural selection. This technique has been applied to the design of coils for the NCSX. Typically > 30 coil contours are needed to reproduce the necessary accuracy. Using GA, the result can be improved by choosing a small subset (e.g. 10) contours, each carrying different currents from among a much larger number (e.g. 50).

  12. 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.

  13. The tyrosine kinase inhibitor bafetinib inhibits PAR2-induced activation of TRPV4 channels in vitro and pain in vivo

    PubMed Central

    Grace, M S; Lieu, T; Darby, B; Abogadie, F C; Veldhuis, N; Bunnett, N W; McIntyre, P

    2014-01-01

    BACKGROUND AND PURPOSE Protease-activated receptor 2 (PAR2) is expressed on nociceptive neurons, and can sensitize transient receptor potential (TRP) ion channels to amplify neurogenic inflammation and pain. The mechanisms by which this occurs are not fully understood. PAR2 causes receptor-operated activation of TRPV4 channels and TRPV4 null mice have attenuated PAR2-stimulated neurogenic inflammation and mechanical hyperalgesia. Here we investigate the intracellular signalling mechanisms underlying PAR2-induced TRPV4 channel activation and pain. EXPERIMENTAL APPROACH Responses of non-transfected and TRPV4-transfected HEK293 cells to agonists of PAR2 (trypsin and SLIGRL) and TRPV4 channels (GSK1016790A) were determined using calcium imaging. Inhibitors of TRPV4 channels (HC067047), sarcoendoplasmic reticulum calcium transport ATPase (thapsigargin), Gαq (UBO-QIC), tyrosine kinases (bafetinib and dasatinib) or PI3 kinases (wortmannin and LY294002) were used to investigate signalling mechanisms. In vivo effects of tyrosine kinase inhibitors on PAR2-induced mechanical hyperalgesia were assessed in mice. KEY RESULTS In non-transfected HEK293 cells, PAR2 activation transiently increased intracellular calcium ([Ca2+]i). Functional expression of TRPV4 channels caused a sustained increase of [Ca2+]i, inhibited by HC067047, bafetinib and wortmannin; but not by thapsigargin, UBO-QIC, dasatinib or LY294002. Bafetinib but not dasatinib inhibited PAR2-induced mechanical hyperalgesia in vivo. CONCLUSIONS AND IMPLICATIONS This study supports a role for tyrosine kinases in PAR2-mediated receptor-operated gating of TRPV4 channels, independent of Gαq stimulation. The ability of a tyrosine kinase inhibitor to diminish PAR2-induced activation of TRPV4 channels and consequent mechanical hyperalgesia identifies bafetinib (which is in development in oncology) as a potential novel analgesic therapy. PMID:24779362

  14. 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.

  15. 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.

  16. 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.

  17. Tungsten coil atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Rust, Jennifer A.; Nóbrega, Joaquim A.; Calloway, Clifton P.; Jones, Bradley T.

    2006-02-01

    A tungsten coil atomic emission spectrometer is described and evaluated. The system employs a single tungsten coil as a combined atomizer and excitation source for the determination of metals by atomic emission spectrometry. The tungsten coil is extracted from a 150 W, 15 V commercial slide projector light bulb. A simple, laboratory constructed, computer-controlled power supply provides a constant current to the coil. A high-resolution Czerny-Turner monochromator with a charge coupled device detector completes the system. Simultaneous, multi-element analyses are possible within a 4 nm spectral window. Eleven test elements are used to characterize the system: Al (396.1 nm), Co (353.0 nm), Cr (427.1 nm), Dy (404.6 nm), Ga (403.3 nm), K (404.4 nm), Mn (403.1 nm), Pb (405.8 nm), Rb (420.2 nm), Sc (404.8 nm), and Yb (398.7 nm). Tungsten coil atomic emission detection limits are reported for these elements for the first time: 0.02 ng Al, 0.7 ng Co, 0.003 ng Cr, 0.01 ng Dy, 0.7 ng Ga, 0.3 ng K, 0.04 ng Mn, 10 ng Pb, 0.07 ng Rb, 1 ng Sc, and 0.003 ng Yb. The precision for the new technique is better than 13% relative standard deviation for all metals at concentrations two orders of magnitude above the detection limit. Aluminum, Cr, Mn, and K are determined in a standard reference material (trace elements in water) after simple dilution with water, and found values varied from certified values by up to 26%. The average tungsten coil lifetime was found to be 265 heating cycles. The elimination of the external radiation source needed for atomic absorption measurements results in an emission system that could be quite portable.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Sedimentation of wormlike coils. II

    NASA Astrophysics Data System (ADS)

    Hearst, John E.; Reese, Dennis A.

    1980-09-01

    An application of the theories of Hearst and Stockmayer for the sedimentation coefficient of wormlike coils of length shorter than 2.2 Kuhn statistical lengths, and Gray, Bloomfield and Hearst for longer wormlike coils with excluded volume to recent sedimentation data on homogeneous DNA samples is presented. The data is entirely consistent with the predictions of the theories. The molecular parameters obtained from the analysis of the data are a Kuhn statistical length at 0.2 ionic strength of 1150 Å; at 0.1 ionic strength of 1290 Å; and a chain backbone diameter of 20-30 Å.

  3. 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

  4. [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.

  5. 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.

  6. 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

  7. 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.

  8. Magnetic Field Modeling with a Set of Individual Localized Coils

    PubMed Central

    Juchem, Christoph; Nixon, Terence W.; McIntyre, Scott; Rothman, Douglas L.; de Graaf, Robin A.

    2010-01-01

    A set of generic, circular individual coils is shown to be capable of generating highly complex magnetic field distributions in a flexible fashion. Arbitrarily oriented linear field gradients can be generated in three-dimensional as well as sliced volumes at amplitudes that allow imaging applications. The multi-coil approach permits the simultaneous generation of linear MRI encoding fields and complex shim fields by the same setup, thereby reducing system complexity. The choice of the sensitive volume over which the magnetic fields are optimized remains temporally and spatially variable at all times. The restriction of the field synthesis to experimentally relevant, smaller volumes such as single slices directly translates into improved efficiency, i.e. higher magnetic field amplitudes and/or reduced coil currents. For applications like arterial spin labeling, signal spoiling and diffusion weighting, perfect linearity of the gradient fields is not required and reduced demands on accuracy can also be readily translated into improved efficiency. The first experimental realization was achieved for mouse head MRI with 24 coils that were mounted on the surface of a cylindrical former. Oblique linear field gradients of 20 kHz/cm (47 mT/m) were generated with a maximum current of 1.4 A which allowed radial imaging of a mouse head. The potential of the new approach for generating arbitrary magnetic field shapes is demonstrated by synthesizing the more complex, higher order spherical harmonic magnetic field distributions X2-Y2, Z2 and Z2X. The new multi-coil approach provides the framework for the integration of conventional imaging and shim coils into a single multi-coil system in which shape, strength, accuracy and spatial coverage of the magnetic field can be specifically optimized for the application at hand. PMID:20347360

  9. 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.

  10. Coiling Direction of Globigerina pachyderma as a Climatic Index.

    PubMed

    Ericson, D B

    1959-07-24

    An interdependence between the geographical distribution of dextral and sinistral populations of the planktonic foraminifer, Globigerina pachyderma, and sea surface-temperatures is demonstrated. It is inferred that changes in dominant coiling direction at lower levels in sediment cores from the North Atlantic record southward shifts of isotherms during the last ice age.

  11. 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

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

    PubMed

    Monaghan, Kevin; McNaughten, Jennifer; McGahon, Mary K; Kelly, Catriona; Kyle, Daniel; Yong, Phaik Har; McGeown, J Graham; Curtis, Tim M

    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 25 mM 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

  13. 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.

  14. 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.)

  15. 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.

  16. 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.)

  17. 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.

  18. 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.

  19. 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.

  20. High-resolution microscopy coil MR-Eye.

    PubMed

    Georgouli, T; James, T; Tanner, S; Shelley, D; Nelson, M; Chang, B; Backhouse, O; McGonagle, D

    2008-08-01

    The eye is involved in several pathologies where precise identification of the underlying condition is essential for the optimal patient care. This preliminary report presents the potential of high-resolution microscopy coil magnetic resonance imaging (HR-MRI) to undertake this task being actively used in the clinical setting. We used a commercially available MRI scanner and a microscopy surface coil. Exquisite anatomic detail of the eye and orbit with depiction of previously unobserved structures and clear demonstration of the underlying pathology was achieved. This report supports the idea that orbital imaging can be revolutionized with the introduction of HR-MRI with broad clinical implications.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. A 16-element phased-array head coil.

    PubMed

    Porter, J R; Wright, S M; Reykowski, A

    1998-08-01

    Volume-array coils offer increased signal-to-noise ratio (SNR) over standard volume coils near the array elements while preserving the SNR at the center of the volume. As the number of array elements is increased, the SNR advantage as well as the complexity of actually constructing the array increases also. In this study, a 16-channel receive-only array for imaging of the brain is demonstrated and compared to a circularly polarized (CP) head coil of similar shape and diameter. The array was formed from a 2 x 8 grid of square elements placed on a cylindrical form. Mutual coupling was minimized by a combination of overlapping element placement and current-reducing matching networks. Simultaneous data acquisition from the 16 individual elements was performed using a four-channel receiver system with each channel time domain multiplexed by a factor of 4. Theoretical and experimental comparisons between the array and a standard CP head coil show that the array offers an increase in SNR of nearly a factor of 3 near its surface while maintaining a comparable SNR to that of the CP head coil in the center of the region of interest.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

    2017-06-01

    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. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  16. Structural determinants of 5',6'-epoxyeicosatrienoic acid binding to and activation of TRPV4 channel.

    PubMed

    Berna-Erro, Alejandro; Izquierdo-Serra, Mercè; Sepúlveda, Romina V; Rubio-Moscardo, Fanny; Doñate-Macián, Pau; Serra, Selma A; Carrillo-Garcia, Julia; Perálvarez-Marín, Alex; González-Nilo, Fernando; Fernández-Fernández, José M; Valverde, Miguel A

    2017-09-05

    TRPV4 cation channel activation by cytochrome P450-mediated derivatives of arachidonic acid (AA), epoxyeicosatrienoic acids (EETs), constitute a major mechanisms of endothelium-derived vasodilatation. Besides, TRPV4 mechano/osmosensitivity depends on phospholipase A2 (PLA2) activation and subsequent production of AA and EETs. However, the lack of evidence for a direct interaction of EETs with TRPV4 together with claims of EET-independent mechanical activation of TRPV4 has cast doubts on the validity of this mechanism. We now report: 1) The identification of an EET-binding pocket that specifically mediates TRPV4 activation by 5',6'-EET, AA and hypotonic cell swelling, thereby suggesting that all these stimuli shared a common structural target within the TRPV4 channel; and 2) A structural insight into the gating of TRPV4 by a natural agonist (5',6'-EET) in which K535 plays a crucial role, as mutant TRPV4-K535A losses binding of and gating by EET, without affecting GSK1016790A, 4α-phorbol 12,13-didecanoate and heat mediated channel activation. Together, our data demonstrates that the mechano- and osmotransducing messenger EET gates TRPV4 by a direct action on a site formed by residues from the S2-S3 linker, S4 and S4-S5 linker.

  17. Swelling and Eicosanoid Metabolites Differentially Gate TRPV4 Channels in Retinal Neurons and Glia

    PubMed Central

    Ryskamp, Daniel A.; Jo, Andrew O.; Frye, Amber M.; Vazquez-Chona, Felix; MacAulay, Nanna; Thoreson, Wallace B.

    2014-01-01

    Activity-dependent shifts in ionic concentrations and water that accompany neuronal and glial activity can generate osmotic forces with biological consequences for brain physiology. Active regulation of osmotic gradients and cellular volume requires volume-sensitive ion channels. In the vertebrate retina, critical support to volume regulation is provided by Müller astroglia, but the identity of their osmosensor is unknown. Here, we identify TRPV4 channels as transducers of mouse Müller cell volume increases into physiological responses. Hypotonic stimuli induced sustained [Ca2+]i elevations that were inhibited by TRPV4 antagonists and absent in TRPV4−/− Müller cells. Glial TRPV4 signals were phospholipase A2- and cytochrome P450-dependent, characterized by slow-onset and Ca2+ waves, and, in excess, were sufficient to induce reactive gliosis. In contrast, neurons responded to TRPV4 agonists and swelling with fast, inactivating Ca2+ signals that were independent of phospholipase A2. Our results support a model whereby swelling and proinflammatory signals associated with arachidonic acid metabolites differentially gate TRPV4 in retinal neurons and glia, with potentially significant consequences for normal and pathological retinal function. PMID:25411497

  18. TRPV4 channels activity in bovine articular chondrocytes: regulation by obesity-associated mediators.

    PubMed

    Sánchez, Julio C; López-Zapata, Diego F; Wilkins, Robert J

    2014-12-01

    Turnover of the cartilage extracellular matrix depends exclusively on chondrocytes and varies in response to load and osmolarity fluctuations. Obesity can affect chondrocyte physiology; adipokines, insulin and proinflammatory cytokines levels are all altered in the obese and are related to matrix turnover impairments and thus to osteoarthritis. TRPV4, a mechanosensitive cation channel, is responsible for reacting to hypotonic variations. In this study, the presence and activity of TRPV4 channels in bovine chondrocytes were evaluated using the whole-cell patch-clamp technique and fluorescence measurements to perform characterisations of these channels and to determine intracellular calcium responses. The expression of TRPV4 was determined by RT-PCR. The TRPV4 regulation by hypotonic shock, insulin and adipokines were analysed. Hypoosmolarity induced a Gd(3+)-, ruthenium red-, and HC-067047-sensitive current, predominantly inward, an intracellular Ca(2+) concentration increase and a membrane depolarisation. The current had a reversal potential of +28±4mV and exhibited preferential permeability to Ca(2+); 4αPDD, a specific TRPV4 agonist, evoked the same response. TNFα, IL-1β, insulin, and, to a lesser degree, leptin and resistin attenuated the TRPV4-mediated effects; in contrast, adiponectin did not affect them. These results confirm the function of TRPV4 in bovine articular chondrocytes and its regulation by obesity-associated mediators. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. 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

  20. 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

  1. Swelling and eicosanoid metabolites differentially gate TRPV4 channels in retinal neurons and glia.

    PubMed

    Ryskamp, Daniel A; Jo, Andrew O; Frye, Amber M; Vazquez-Chona, Felix; MacAulay, Nanna; Thoreson, Wallace B; Križaj, David

    2014-11-19

    Activity-dependent shifts in ionic concentrations and water that accompany neuronal and glial activity can generate osmotic forces with biological consequences for brain physiology. Active regulation of osmotic gradients and cellular volume requires volume-sensitive ion channels. In the vertebrate retina, critical support to volume regulation is provided by Müller astroglia, but the identity of their osmosensor is unknown. Here, we identify TRPV4 channels as transducers of mouse Müller cell volume increases into physiological responses. Hypotonic stimuli induced sustained [Ca(2+)]i elevations that were inhibited by TRPV4 antagonists and absent in TRPV4(-/-) Müller cells. Glial TRPV4 signals were phospholipase A2- and cytochrome P450-dependent, characterized by slow-onset and Ca(2+) waves, and, in excess, were sufficient to induce reactive gliosis. In contrast, neurons responded to TRPV4 agonists and swelling with fast, inactivating Ca(2+) signals that were independent of phospholipase A2. Our results support a model whereby swelling and proinflammatory signals associated with arachidonic acid metabolites differentially gate TRPV4 in retinal neurons and glia, with potentially significant consequences for normal and pathological retinal function. Copyright © 2014 the authors 0270-6474/14/3415689-12$15.00/0.

  2. 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.

  3. Design of a shielded coil element of a matrix gradient coil

    NASA Astrophysics Data System (ADS)

    Jia, Feng; Littin, Sebastian; Layton, Kelvin J.; Kroboth, Stefan; Yu, Huijun; Zaitsev, Maxim

    2017-08-01

    The increasing interest in spatial encoding with non-linear magnetic fields has intensified the need for coils that generates such fields. Matrix coils consisting of multiple coil elements appear to offer a high flexibility in generating customized encoding fields and are particularly promising for localized high resolution imaging applications. However, coil elements of existing matrix coils were primarily designed and constructed for better shimming and therefore are not expected to achieve an optimal performance for local spatial encoding. Moreover, eddy current properties of such coil elements were not fully explored. In this work, an optimization problem is formulated based on the requirement of local non-linear encoding and eddy current reduction that results in novel designs of coil elements for an actively-shielded matrix gradient coil. Two metrics are proposed to assess the performance of different coil element designs. The results are analyzed to reveal new insights into coil element design.

  4. 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

  5. Rho-associated coiled-coil containing kinases (ROCK)

    PubMed Central

    Julian, Linda; Olson, Michael F

    2014-01-01

    Rho-associated coiled-coil containing kinases (ROCK) were originally identified as effectors of the RhoA small GTPase.1–5 They belong to the AGC family of serine/threonine kinases6 and play vital roles in facilitating actomyosin cytoskeleton contractility downstream of RhoA and RhoC activation. Since their discovery, ROCK kinases have been extensively studied, unveiling their manifold functions in processes including cell contraction, migration, apoptosis, survival, and proliferation. Two mammalian ROCK homologs have been identified, ROCK1 (also called ROCK I, ROKβ, Rho-kinase β, or p160ROCK) and ROCK2 (also known as ROCK II, ROKα, or Rho kinase), hereafter collectively referred to as ROCK. In this review, we will focus on the structure, regulation, and functions of ROCK. PMID:25010901

  6. 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.

  7. Ion pairs significantly stabilize coiled-coils in the absence of electrolyte.

    PubMed

    Yu, Y; Monera, O D; Hodges, R S; Privalov, P L

    1996-01-26

    We have used a synthetic coiled-coil peptide model system to address the long perplexing issue as to why coiled-coils are in general more stable at acidic pH than at neutral pH. Contrary to the above expectation, our results show that at low ionic strength (10 mM) the coiled-coil was much more stable at neutral pH than at acidic pH against both thermal and urea unfolding, indicating that the Lys(+)-Glu- ions pairs present around the coiled-coil interface at neutral pH contribute significantly to the stability of the coiled-coil. However, while the addition of NaCl had no significant effect on the coiled-coil stability at neutral pH, its stability at acidic pH increased dramatically. The cross-over point between the stability at acidic pH and neutral pH occurred at around 100 mM salt, above which the coiled-coil became more stable at acidic pH, in agreement with published results. Therefore, salt effect, rather than intrinsic property, such as carboxyl-carboxyl hydrogen bonding, causes this coiled-coil to become more stable at acidic pH. The preferential stabilizing effect of salt on the coiled-coil at acidic pH can be best explained in terms of the condensation of anions to the positively charged groups on the coiled-coil, the net density of which increases as glutamic acid residues become protonated in acidic pH.

  8. Evaluation of Common RF Coil Setups for MR Imaging at Ultrahigh Magnetic Field: A Numerical Study.

    PubMed

    Lu, Jonathan; Pang, Yong; Wang, Chunsheng; Wu, Bing; Vigneron, Daniel B; Zhang, Xiaoliang

    2011-01-01

    This study is an evaluation of the ratio of electric field to magnetic field (E/B1), specific absorption rate (SAR) and signal-to-noise ratio (SNR) generated by three different RF transceiver coil setups: surface coil, surface coil with shielding, and microstrip using a finite discrete time domain (FDTD) simulation in the presence of a head phantom. One of our main focuses in this study is to better understand coil designs that would improve patient safety at high fields by studying a coil type that may potentially minimize SAR while examining potential changes in SNR. In the presence of a human head load, the microstrip's E/B1 ratio was on average smallest while its SAR was also on average smallest of the three setups, suggesting the microstrip may be a better RF coil choice for MRI concerning patient safety and parallel excitation applications than the other two coils. In addition, the study suggests that the microstrip also has a higher SNR compared with the other two coils demonstrating the possibility that the microstrip could lead to higher quality MRI images.

  9. Evaluation of Common RF Coil Setups for MR Imaging at Ultrahigh Magnetic Field: A Numerical Study

    PubMed Central

    Lu, Jonathan; Pang, Yong; Wang, Chunsheng; Wu, Bing; Vigneron, Daniel B

    2017-01-01

    This study is an evaluation of the ratio of electric field to magnetic field (E/B1), specific absorption rate (SAR) and signal-to-noise ratio (SNR) generated by three different RF transceiver coil setups: surface coil, surface coil with shielding, and microstrip using a finite discrete time domain (FDTD) simulation in the presence of a head phantom. One of our main focuses in this study is to better understand coil designs that would improve patient safety at high fields by studying a coil type that may potentially minimize SAR while examining potential changes in SNR. In the presence of a human head load, the microstrip's E/B1 ratio was on average smallest while its SAR was also on average smallest of the three setups, suggesting the microstrip may be a better RF coil choice for MRI concerning patient safety and parallel excitation applications than the other two coils. In addition, the study suggests that the microstrip also has a higher SNR compared with the other two coils demonstrating the possibility that the microstrip could lead to higher quality MRI images. PMID:28966929

  10. 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.

  11. 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.

  12. Performance evaluation of matrix gradient coils.

    PubMed

    Jia, Feng; Schultz, Gerrit; Testud, Frederik; Welz, Anna Masako; Weber, Hans; Littin, Sebastian; Yu, Huijun; Hennig, Jürgen; Zaitsev, Maxim

    2016-02-01

    In this paper, we present a new performance measure of a matrix coil (also known as multi-coil) from the perspective of efficient, local, non-linear encoding without explicitly considering target encoding fields. An optimization problem based on a joint optimization for the non-linear encoding fields is formulated. Based on the derived objective function, a figure of merit of a matrix coil is defined, which is a generalization of a previously known resistive figure of merit for traditional gradient coils. A cylindrical matrix coil design with a high number of elements is used to illustrate the proposed performance measure. The results are analyzed to reveal novel features of matrix coil designs, which allowed us to optimize coil parameters, such as number of coil elements. A comparison to a scaled, existing multi-coil is also provided to demonstrate the use of the proposed performance parameter. The assessment of a matrix gradient coil profits from using a single performance parameter that takes the local encoding performance of the coil into account in relation to the dissipated power.

  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. 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

  16. TRPV4 channels in the human urogenital tract play a role in cell junction formation and epithelial barrier.

    PubMed

    Janssen, D A W; Jansen, C J F; Hafmans, T G; Verhaegh, G W; Hoenderop, J G; Heesakkers, J P F A; Schalken, J A

    2016-09-01

    The molecular interactions between transient receptor potential vanilloid subtype 4 channels (TRPV4) and cell junction formation were investigated in the human and mouse urogenital tract. A qualitative study was performed to investigate TRPV4 channels, adherence junctions (AJs) and tight junctions (TJs) in kidney, ureter and bladder tissues from humans and wild-type and transgenic TRPV4 knockout (-/-) mice with immunohistochemistry, Western blotting, immunoprecipitation and reverse trasnscription-PCR. Cell junction formation in the wild-type and TRPV4 knockout (-/-) mouse was evaluated with immunohistochemistry and transmission electron microscope (TEM) techniques. TRPV4 channels are predominantly located in membranes of epithelial cells of the bladder, ureter and the collecting ducts of the kidney. There is a molecular interaction between the TRPV4 channel and the AJ. TEM evaluation showed that AJ formation is disrupted in the TRPV4 -/- mouse resulting in deficient intercellular connections and integrity of the epithelium. TRPV4 is believed to be a mechanoreceptor in the bladder. This study demonstrates that TRPV4 is also involved in intercellular connectivity and structural integrity of the epithelium. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. TRPV4 channels augment macrophage activation and ventilator-induced lung injury

    PubMed Central

    Hamanaka, Kazutoshi; Jian, Ming-Yuan; Townsley, Mary I.; King, Judy A.; Liedtke, Wolfgang; Weber, David S.; Eyal, Fabien G.; Clapp, Mary M.

    2010-01-01

    We have previously implicated transient receptor potential vanilloid 4 (TRPV4) channels and alveolar macrophages in initiating the permeability increase in response to high peak inflation pressure (PIP) ventilation. Alveolar macrophages were harvested from TRPV4−/− and TRPV4+/+ mice and instilled in the lungs of mice of the opposite genotype. Filtration coefficients (Kf) measured in isolated perfused lungs after ventilation with successive 30-min periods of 9, 25, and 35 cmH2O PIP did not significantly increase in lungs from TRPV4−/− mice but increased >2.2-fold in TRPV4+/+ lungs, TRPV4+/+ lungs instilled with TRPV4−/− macrophages, and TRPV4−/− lungs instilled with TRPV4+/+ macrophages after ventilation with 35 cmH2O PIP. Activation of TRPV4 with 4-α-phorbol didecanoate (4αPDD) significantly increased intracellular calcium, superoxide, and nitric oxide production in TRPV4+/+ macrophages but not TRPV4−/− macrophages. Cross-sectional areas increased nearly 3-fold in TRPV4+/+ macrophages compared with TRPV4−/− macrophages after 4αPDD. Immunohistochemistry staining of lung tissue for nitrotyrosine revealed increased amounts in high PIP ventilated TRPV4+/+ lungs compared with low PIP ventilated TRPV4+/+ or high PIP ventilated TRPV4−/− lungs. Thus TRPV4+/+ macrophages restored susceptibility of TRPV4−/− lungs to mechanical injury. A TRPV4 agonist increased intracellular calcium and reactive oxygen and nitrogen species in harvested TRPV4+/+ macrophages but not TRPV4−/− macrophages. Kf increases correlated with tissue nitrotyrosine, a marker of peroxynitrite production. PMID:20562229

  2. Role of endothelial TRPV4 channels in vascular actions of the endocannabinoid, 2-arachidonoylglycerol.

    PubMed

    Ho, W S V; Zheng, X; Zhang, D X

    2015-11-01

    Metabolites of the endocannabinoid, 2-arachidonoylglycerol (2-AG) have been postulated to act as endogenous activators of TRPV4, a Ca(2+) -permeable cation channel that plays a critical role in endothelium-dependent relaxation. However, it is unclear if TRPV4 contributes to the vascular actions of 2-AG. Isometric tension recording of rat small mesenteric arteries and aortae were used to assess the effect of 2-AG and the synthetic TRPV4 activator, GSK1016790A (GSK) on vascular reactivity. Changes in intracellular Ca(2+) concentration and single-channel currents were measured in TRPV4-expressing human coronary endothelial cells. In mesenteric arteries, endothelium-dependent relaxation to both 2-AG and GSK was attenuated by structurally distinct TRPV4 antagonists, HC067047, RN1734 and ruthenium red. The responses were inhibited by KCa inhibitors (apamin + charybdotoxin) and a gap junction inhibitor (18α-glycyrrhetinic acid). In contrast to GSK, 2-AG elicited considerable relaxation independently of the endothelium or TRPV4. Inhibition of 2-AG metabolism via monoacylglycerol lipase and COX (by MAFP and indomethacin) caused potentiation, while cytochrome P450 and lipoxygenase inhibitors had no effect on 2-AG relaxation. In coronary endothelial cells, 2-AG (with and without MAFP) induced HC067047-sensitive increases in intracellular Ca(2+) concentration. 2-AG also increased TRPV4 channel opening in inside-out patches. However, in aortae, GSK induced a relaxation sensitive to HC067047 and ruthenium red, whereas 2-AG induced contractions. These data suggest that 2-AG can directly activate endothelial TRPV4, which partly contributes to the relaxant response to 2-AG. However, the functional role of TRPV4 is highly dependent on the vascular region. © 2015 The British Pharmacological Society.

  3. 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.

  4. 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.

  5. Detection of TRPV4 channel current-like activity in Fawn Hooded hypertensive (FHH) rat cerebral arterial muscle cells.

    PubMed

    Gebremedhin, Debebe; Zhang, David X; Weihrauch, Dorothee; Uche, Nnamdi N; Harder, David R

    2017-01-01

    The transient receptor potential vallinoid type 4 (TRPV4) is a calcium entry channel known to modulate vascular function by mediating endothelium-dependent vasodilation. The present study investigated if isolated cerebral arterial myocytes of the Fawn Hooded hypertensive (FHH) rat, known to display exaggerated KCa channel current activity and impaired myogenic tone, express TRPV4 channels at the transcript and protein level and exhibit TRPV4-like single-channel cationic current activity. Reverse transcription polymerase chain reaction (RT-PCR), Western blot, and immunostaining analysis detected the expression of mRNA transcript and translated protein of TRPV4 channel in FHH rat cerebral arterial myocytes. Patch clamp recording of single-channel current activity identified the presence of a single-channel cationic current with unitary conductance of ~85 pS and ~96 pS at hyperpolarizing and depolarizing potentials, respectively, that was inhibited by the TRPV4 channel antagonist RN 1734 or HC 067074 and activated by the potent TRPV4 channel agonist GSK1016790A. Application of negative pressure via the interior of the patch pipette increased the NPo of the TRPV4-like single-channel cationic current recorded in cell-attached patches at a patch potential of 60 mV that was inhibited by prior application of the TRPV4 channel antagonist RN 1734 or HC 067047. Treatment with the TRPV4 channel agonist GSK1016790A caused concentration-dependent increase in the NPo of KCa single-channel current recorded in cell-attached patches of cerebral arterial myocytes at a patch potential of 40 mV, which was not influenced by pretreatment with the voltage-gated L-type Ca2+ channel blocker nifedipine or the T-type Ca2+ channel blocker Ni2+. These findings demonstrate that FHH rat cerebral arterial myocytes express mRNA transcript and translated protein for TRPV4 channel and display TRPV4-like single-channel cationic current activity that was stretch-sensitive and activation of which

  6. Detection of TRPV4 channel current-like activity in Fawn Hooded hypertensive (FHH) rat cerebral arterial muscle cells

    PubMed Central

    Zhang, David X.; Weihrauch, Dorothee; Uche, Nnamdi N.; Harder, David R.

    2017-01-01

    The transient receptor potential vallinoid type 4 (TRPV4) is a calcium entry channel known to modulate vascular function by mediating endothelium–dependent vasodilation. The present study investigated if isolated cerebral arterial myocytes of the Fawn Hooded hypertensive (FHH) rat, known to display exaggerated KCa channel current activity and impaired myogenic tone, express TRPV4 channels at the transcript and protein level and exhibit TRPV4-like single-channel cationic current activity. Reverse transcription polymerase chain reaction (RT-PCR), Western blot, and immunostaining analysis detected the expression of mRNA transcript and translated protein of TRPV4 channel in FHH rat cerebral arterial myocytes. Patch clamp recording of single-channel current activity identified the presence of a single-channel cationic current with unitary conductance of ~85 pS and ~96 pS at hyperpolarizing and depolarizing potentials, respectively, that was inhibited by the TRPV4 channel antagonist RN 1734 or HC 067074 and activated by the potent TRPV4 channel agonist GSK1016790A. Application of negative pressure via the interior of the patch pipette increased the NPo of the TRPV4-like single-channel cationic current recorded in cell-attached patches at a patch potential of 60 mV that was inhibited by prior application of the TRPV4 channel antagonist RN 1734 or HC 067047. Treatment with the TRPV4 channel agonist GSK1016790A caused concentration-dependent increase in the NPo of KCa single-channel current recorded in cell-attached patches of cerebral arterial myocytes at a patch potential of 40 mV, which was not influenced by pretreatment with the voltage-gated L-type Ca2+ channel blocker nifedipine or the T-type Ca2+ channel blocker Ni2+. These findings demonstrate that FHH rat cerebral arterial myocytes express mRNA transcript and translated protein for TRPV4 channel and display TRPV4-like single-channel cationic current activity that was stretch-sensitive and activation of which

  7. 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.

  8. Magnetic field homogeneity of a conical coaxial coil pair.

    PubMed

    Salazar, F J; Nieves, F J; Bayón, A; Gascón, F

    2017-09-01

    An analytical study of the magnetic field created by a double-conical conducting sheet is presented. The analysis is based on the expansion of the magnetic field in terms of Legendre polynomials. It is demonstrated analytically that the angle of the conical surface that produces a nearly homogeneous magnetic field coincides with that of a pair of loops that fulfills the Helmholtz condition. From the results obtained, we propose an electric circuit formed by pairs of isolated conducting loops tightly wound around a pair of conical surfaces, calculating numerically the magnetic field produced by this system and its heterogeneity. An experimental setup of the proposed circuit was constructed and its magnetic field was measured. The results were compared with those obtained by numerical calculation, finding a good agreement. The numerical results demonstrate a significant improvement in homogeneity in the field of the proposed pair of conical coils compared with that achieved with a simple pair of Helmholtz loops or with a double solenoid. Moreover, a new design of a double pair of conical coils based on Braunbek's four loops is also proposed to achieve greater homogeneity. Regarding homogeneity, the rating of the analyzed configurations from best to worst is as follows: (1) double pair of conical coils, (2) pair of conical coils, (3) Braunbek's four loops, (4) Helmholtz pair, and (5) solenoid pair.

  9. 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.

  10. 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.

  11. Structural implications of conserved aspartate residues located in tropomyosin’s coiled-coil core

    PubMed Central

    Moore, Jeffrey R.; Li, Xiaochuan; Nirody, Jasmine; Fischer, Stefan; Lehman, William

    2011-01-01

    Polar residues lying between adjacent α-helical chains of coiled-coils often contribute to coiled-coil curvature and flexibility, while more typical core hydrophobic residues anneal the chains together. In tropomyosins, ranging from smooth and skeletal muscle to cytoplasmic isoforms, a highly conserved Asp at residue 137 places negative charges within the tropomyosin coiled-coil core in a position which may affect the conformation needed for tropomyosin binding and regulatory movements on actin. Proteolytic susceptibility suggested that substituting a canonical Leu for the naturally occurring Asp at residue 137 increases inter-chain rigidity by stabilizing the tropomyosin coiled-coil. Using molecular dynamics, we now directly assess changes in coiled-coil curvature and flexibility caused by such mutants. Although the coiled-coil flexibility is modestly diminished near the residue 137 mutation site, as expected, a delocalized increase in flexibility along the overall coiled-coil is observed. Even though the average shape of the D137L tropomyosin is straighter than that of wild-type tropomyosin, it is still capable of binding actin due to this increase in flexibility. We conclude that the conserved, non-canonical Asp-137 destabilizes the local structure resulting in a local flexible region in the middle of tropomyosin that normally is important for tropomyosin steady-state equilibrium position on actin. PMID:22754618

  12. Exploring alternate states and oligomerization preferences of coiled-coils by de novo structure modeling.

    PubMed

    Rämisch, Sebastian; Lizatović, Robert; André, Ingemar

    2015-02-01

    Homomeric coiled-coils can self-assemble into a wide range of structural states with different helix topologies and oligomeric states. In this study, we have combined de novo structure modeling with stability calculations to simultaneously predict structure and oligomeric states of homomeric coiled-coils. For dimers an asymmetric modeling protocol was developed. Modeling without symmetry constraints showed that backbone asymmetry is important for the formation of parallel dimeric coiled-coils. Collectively, our results demonstrate that high-resolution structure of coiled-coils, as well as parallel and antiparallel orientations of dimers and tetramers, can be accurately predicted from sequence. De novo modeling was also used to generate models of competing oligomeric states, which were used to compare stabilities and thus predict the native stoichiometry from sequence. In a benchmark set of 33 coiled-coil sequences, forming dimers to pentamers, up to 70% of the oligomeric states could be correctly predicted. The calculations demonstrated that the free energy of helix folding could be an important factor for determining stability and oligomeric state of homomeric coiled-coils. The computational methods developed here should be broadly applicable to studies of sequence-structure relationships in coiled-coils and the design of higher order assemblies with improved oligomerization specificity. © 2014 Wiley Periodicals, Inc.

  13. 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

  14. 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.

  15. 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%.

  16. Coiled-coil protein composition of 22 proteomes – differences and common themes in subcellular infrastructure and traffic control

    PubMed Central

    Rose, Annkatrin; Schraegle, Shannon J; Stahlberg, Eric A; Meier, Iris

    2005-01-01

    Background Long alpha-helical coiled-coil proteins are involved in diverse organizational and regulatory processes in eukaryotic cells. They provide cables and networks in the cyto- and nucleoskeleton, molecular scaffolds that organize membrane systems and tissues, motors, levers, rotating arms, and possibly springs. Mutations in long coiled-coil proteins have been implemented in a growing number of human diseases. Using the coiled-coil prediction program MultiCoil, we have previously identified all long coiled-coil proteins from the model plant Arabidopsis thaliana and have established a searchable Arabidopsis coiled-coil protein database. Results Here, we have identified all proteins with long coiled-coil domains from 21 additional fully sequenced genomes. Because regions predicted to form coiled-coils interfere with sequence homology determination, we have developed a sequence comparison and clustering strategy based on masking predicted coiled-coil domains. Comparing and grouping all long coiled-coil proteins from 22 genomes, the kingdom-specificity of coiled-coil protein families was determined. At the same time, a number of proteins with unknown function could be grouped with already characterized proteins from other organisms. Conclusion MultiCoil predicts proteins with extended coiled-coil domains (more than 250 amino acids) to be largely absent from bacterial genomes, but present in archaea and eukaryotes. The structural maintenance of chromosomes proteins and their relatives are the only long coiled-coil protein family clearly conserved throughout all kingdoms, indicating their ancient nature. Motor proteins, membrane tethering and vesicle transport proteins are the dominant eukaryote-specific long coiled-coil proteins, suggesting that coiled-coil proteins have gained functions in the increasingly complex processes of subcellular infrastructure maintenance and trafficking control of the eukaryotic cell. PMID:16288662

  17. A Magnetic Resonance (MR) Microscopy System using a Microfluidically Cryo-Cooled Planar Coil

    PubMed Central

    Koo, Chiwan; Godley, Richard F.; Park, Jaewon; McDougall, Mary P.; Wright, Steven M.; Han, Arum

    2011-01-01

    We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (−196°C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: 1) The small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. 2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0°C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system

  18. A magnetic resonance (MR) microscopy system using a microfluidically cryo-cooled planar coil.

    PubMed

    Koo, Chiwan; Godley, Richard F; Park, Jaewon; McDougall, Mary P; Wright, Steven M; Han, Arum

    2011-07-07

    We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (-196 °C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: (1) the small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. (2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0 °C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system

  19. 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.

  20. 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

  1. Second coiled-coil domain of KCNQ channel controls current expression and subfamily specific heteromultimerization by salt bridge networks

    PubMed Central

    Nakajo, Koichi; Kubo, Yoshihiro

    2008-01-01

    KCNQ channels carry the slowly activating, voltage-dependent M-current in excitable cells such as neurons. Although the KCNQ2 homomultimer can form a functional voltage-gated K+ channel, heteromultimerization with KCNQ3 produces a > 10-fold increase in current amplitude. All KCNQ channels contain double coiled-coil domains (TCC1 and TCC2, or A-domain Head and Tail), of which TCC2 (A-domain Tail) is thought to be important for subunit recognition, channel assembly and surface expression. The mechanism by which TCC2 recognizes and associates with its partner is not fully understood, however. Our aim in the present study was to elucidate the recognition mechanism by examining the phenotypes of TCC2-deletion mutants, TCC2-swapped chimeras and point mutants. Electrophysiological analysis using Xenopus oocytes under two-electrode voltage clamp revealed that homotetrameric KCNQ3 TCC2 is a negative regulator of current expression in the absence of KCNQ2 TCC2. Recent structural analysis of KCNQ4 TCC2 revealed the presence of intercoil salt bridge networks. We therefore swapped the sign of the charged residues reportedly involved in the salt bridge formation and functionally confirmed that the intercoil salt bridge network is responsible for the subunit recognition between KCNQ2 and KCNQ3. Finally, we constructed TCC2-swapped KCNQ2/KCNQ3 mutants with KCNQ1 TCC2 or GCN4-pLI, a coiled-coil domain from an unrelated protein, and found that TCC2 is substitutable and even GCN4-pLI can work as a substitute for TCC2. Our present data provide some new insights into the role played by TCC2 during current expression, and also provide functional evidence of the importance of the intercoil salt bridge network for subunit recognition and coiled-coil formation, as is suggested by recent crystallographic data. PMID:18440995

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Characterization of mesoscale coiled-coil peptide-porphyrin complexes.

    PubMed

    Pepe-Mooney, Brian J; Kokona, Bashkim; Fairman, Robert

    2011-12-12

    Photoelectronically conductive self-assembling peptide-porphyrin assemblies have great potential in their use as biomaterials, owing largely to their environmentally responsive properties. We have successfully designed a coiled-coil peptide that can self-assemble to form mesoscale filaments and serve as a scaffold for porphyrin interaction. In our earlier work, peptide-porphyrin-based biomaterials were formed at neutral pH, but the structures were irregular at the nano- to microscale size range, as judged by atomic force microscopy. We identified a pH in which mesoscale fibrils were formed, taking advantage of the types of porphyrin interactions that are present in well-characterized J-aggregates. We used UV-visible spectroscopy, circular dichroism spectropolarimetry, fluorescence spectroscopy, and atomic force microscopy to characterize these self-assembling biomaterials. We propose a new assembly paradigm that arises from a set of unique porphyrin-porphyrin and porphyrin-peptide interactions whose structure may be readily modulated by changes in pH or peptide concentration.

  8. 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

  9. 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.

  10. Resonator coiling in thermoacoustic engines

    SciTech Connect

    Olson, J.R.; Swift, G.W.

    1995-11-01

    Coiling the resonator of a thermoacoustic engine is one way to try to minimize the engine`s size. However, flow in bent pipes is known to alter the fluid flow pattern because of centrifugal forces. Theory and measurements will be presented on the energy dissipation caused by oscillating flow in curved pipes. Measurements have been taken using free oscillations of liquids in U-tubes, and using a thermoacoustic engine with straight and bent resonators. [Work supported by the TTI program of the US Department of Energy, and by the Tektronix Corporation.

  11. Coils of Magnetic Field Lines

    NASA Image and Video Library

    2017-06-27

    A smallish solar filament looks like it collapsed into the sun and set off a minor eruption that hurled plasma into space (June 20, 2017). Then, the disrupted magnetic field immediately began to reorganize itself, hence the bright series of spirals coiling up over that area. The magnetic field lines are made visible in extreme ultraviolet light as charged particles spin along them. Also of interest are the darker, cooler strands of plasma being pulled and twisted at the edge of the sun just below the active region. The activity here is in a 21-hour period. Movies are available at https://photojournal.jpl.nasa.gov/catalog/PIA21764

  12. Water in a Coiled Hose

    NASA Astrophysics Data System (ADS)

    Lemaire, Peter; Waiveris, Charles

    2005-04-01

    Sometimes things just don't work the way that you think they should. The problem "Coming up Empty," described in Bet You Can't! Science Impossibilities to Fool You by Vicki Cobb and Kathy Darling is a perfect example. In this problem, when water is poured into the top open end of a coiled garden hose, common sense tells us that it should eventually come out of the other end. However, in this case the water will overflow from the top instead of coming out of the other end!

  13. 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.

  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. 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.

  17. 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.

  18. Biocide-mediated corrosion of coiled tubing

    PubMed Central

    An, Dongshan; Liu, Tao; Pinnock, Tijan; Cheng, Frank; Voordouw, Gerrit

    2017-01-01

    Coiled tubing corrosion was investigated for 16 field water samples (S5 to S20) from a Canadian shale gas field. Weight loss corrosion rates of carbon steel beads incubated with these field water samples averaged 0.2 mm/yr, but injection water sample S19 had 1.25±0.07 mm/yr. S19 had a most probable number of zero acid-producing bacteria and incubation of S19 with carbon steel beads or coupons did not lead to big changes in microbial community composition. In contrast other field water samples had most probable numbers of APB of 102/mL to 107/mL and incubation of these field water samples with carbon steel beads or coupons often gave large changes in microbial community composition. HPLC analysis indicated that all field water samples had elevated concentrations of bromide (average 1.6 mM), which may be derived from bronopol, which was used as a biocide. S19 had the highest bromide concentration (4.2 mM) and was the only water sample with a high concentration of active bronopol (13.8 mM, 2760 ppm). Corrosion rates increased linearly with bronopol concentration, as determined by weight loss of carbon steel beads, for experiments with S19, with filtered S19 and with bronopol dissolved in defined medium. This indicated that the high corrosion rate found for S19 was due to its high bronopol concentration. The corrosion rate of coiled tubing coupons also increased linearly with bronopol concentration as determined by electrochemical methods. Profilometry measurements also showed formation of multiple pits on the surface of coiled tubing coupon with an average pit depth of 60 μm after 1 week of incubation with 1 mM bronopol. At the recommended dosage of 100 ppm the corrosiveness of bronopol towards carbon steel beads was modest (0.011 mm/yr). Higher concentrations, resulting if biocide is added repeatedly as commonly done in shale gas operations, are more corrosive and should be avoided. Overdosing may be avoided by assaying the presence of residual biocide by HPLC

  19. Eight-channel phased array coil and detunable TEM volume coil for 7 T brain imaging.

    PubMed

    Wiggins, G C; Potthast, A; Triantafyllou, C; Wiggins, C J; Wald, L L

    2005-07-01

    An eight-channel receive-only brain coil and table-top detunable volume transmit coil were developed and tested at 7 T for human imaging. Optimization of this device required attention to sources of interaction between the array elements, between the transmit and receive coils and minimization of common mode currents on the coaxial cables. Circular receive coils (85 mm dia.) were designed on a flexible former to fit tightly around the head and within a 270-mm diameter TEM transmit volume coil. In the near cortex, the array provided a fivefold increase in SNR compared to a TEM transmit-receive coil, a gain larger than that seen in comparable coils at 3 T. The higher SNR gain is likely due to strong dielectric effects, which cause the volume coil to perform poorly in the cortex compared to centrally. The sensitivity and coverage of the array is demonstrated with high-resolution images of the brain cortex.

  20. A precise technique for manufacturing correction coil

    SciTech Connect

    Schieber, L.

    1992-01-01

    An automated method of manufacturing correction coils has been developed which provides a precise embodiment of the coil design. Numerically controlled machines have been developed to accurately position coil windings on the beam tube. Two types of machines have been built. One machine bonds the wire to a substrate which is wrapped around the beam tube after it is completed while the second machine bonds the wire directly to the beam tube. Both machines use the Multiwire[reg sign] technique of bonding the wire to the substrate utilizing an ultrasonic stylus. These machines are being used to manufacture coils for both the SSC and RHIC.

  1. A precise technique for manufacturing correction coil

    SciTech Connect

    Schieber, L.

    1992-11-01

    An automated method of manufacturing correction coils has been developed which provides a precise embodiment of the coil design. Numerically controlled machines have been developed to accurately position coil windings on the beam tube. Two types of machines have been built. One machine bonds the wire to a substrate which is wrapped around the beam tube after it is completed while the second machine bonds the wire directly to the beam tube. Both machines use the Multiwire{reg_sign} technique of bonding the wire to the substrate utilizing an ultrasonic stylus. These machines are being used to manufacture coils for both the SSC and RHIC.

  2. 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.

  3. Mathematical model and its application of radial effective thermal conductivity for coil heat transfer in HPH furnace

    NASA Astrophysics Data System (ADS)

    Wu, Wenfei; Yu, Fan; Zhang, Xinxin; Zuo, Yi

    2002-05-01

    Temperature uniformity of steel coils in High Performance Hydrogen bell-type annealing furnace has a significant effect on their quality and production. The hot rolled coil can be considered as a periodically laminated material composed of steel layers and interface layers in radial direction. A new formula for the radial effective thermal conductivity has been proposed, which is based on surface characteristic, strip thickness and compressive stress of the rolled coil. Furthermore, it has been used to develop a heat transfer mathematical model for steel coils in the HPH furnace. The calculated annealing curves using this mathematical model are in good agreement with the experimental data.

  4. The Increased Activity of TRPV4 Channel in the Astrocytes of the Adult Rat Hippocampus after Cerebral Hypoxia/Ischemia

    PubMed Central

    Butenko, Olena; Dzamba, David; Benesova, Jana; Honsa, Pavel; Benfenati, Valentina; Rusnakova, Vendula; Ferroni, Stefano; Anderova, Miroslava

    2012-01-01

    The polymodal transient receptor potential vanilloid 4 (TRPV4) channel, a member of the TRP channel family, is a calcium-permeable cationic channel that is gated by various stimuli such as cell swelling, low pH and high temperature. Therefore, TRPV4-mediated calcium entry may be involved in neuronal and glia pathophysiology associated with various disorders of the central nervous system, such as ischemia. The TRPV4 channel has been recently found in adult rat cortical and hippocampal astrocytes; however, its role in astrocyte pathophysiology is still not defined. In the present study, we examined the impact of cerebral hypoxia/ischemia (H/I) on the functional expression of astrocytic TRPV4 channels in the adult rat hippocampal CA1 region employing immunohistochemical analyses, the patch-clamp technique and microfluorimetric intracellular calcium imaging on astrocytes in slices as well as on those isolated from sham-operated or ischemic hippocampi. Hypoxia/ischemia was induced by a bilateral 15-minute occlusion of the common carotids combined with hypoxic conditions. Our immunohistochemical analyses revealed that 7 days after H/I, the expression of TRPV4 is markedly enhanced in hippocampal astrocytes of the CA1 region and that the increasing TRPV4 expression coincides with the development of astrogliosis. Additionally, adult hippocampal astrocytes in slices or cultured hippocampal astrocytes respond to the TRPV4 activator 4-alpha-phorbol-12,-13-didecanoate (4αPDD) by an increase in intracellular calcium and the activation of a cationic current, both of which are abolished by the removal of extracellular calcium or exposure to TRP antagonists, such as Ruthenium Red or RN1734. Following hypoxic/ischemic injury, the responses of astrocytes to 4αPDD are significantly augmented. Collectively, we show that TRPV4 channels are involved in ischemia-induced calcium entry in reactive astrocytes and thus, might participate in the pathogenic mechanisms of astroglial reactivity

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. Facilitated diffusion with DNA coiling.

    PubMed

    Lomholt, Michael A; van den Broek, Bram; Kalisch, Svenja-Marei J; Wuite, Gijs J L; Metzler, Ralf

    2009-05-19

    When DNA-binding proteins search for their specific binding site on a DNA molecule they alternate between linear 1-dimensional diffusion along the DNA molecule, mediated by nonspecific binding, and 3-dimensional volume excursion events between successive dissociation from and rebinding to DNA. If the DNA molecule is kept in a straight configuration, for instance, by optical tweezers, these 3-dimensional excursions may be divided into long volume excursions and short hops along the DNA. These short hops correspond to immediate rebindings after dissociation such that a rebinding event to the DNA occurs at a site that is close to the site of the preceding dissociation. When the DNA molecule is allowed to coil up, immediate rebinding may also lead to so-called intersegmental jumps, i.e., immediate rebindings to a DNA segment that is far away from the unbinding site when measured in the chemical distance along the DNA, but close by in the embedding 3-dimensional space. This effect is made possible by DNA looping. The significance of intersegmental jumps was recently demonstrated in a single DNA optical tweezers setup. Here we present a theoretical approach in which we explicitly take the effect of DNA coiling into account. By including the spatial correlations of the short hops we demonstrate how the facilitated diffusion model can be extended to account for intersegmental jumping at varying DNA densities. It is also shown that our approach provides a quantitative interpretation of the experimentally measured enhancement of the target location by DNA-binding proteins.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Natural templates for coiled-coil biomaterials from praying mantis egg cases.

    PubMed

    Walker, Andrew A; Weisman, Sarah; Kameda, Tsunenori; Sutherland, Tara D

    2012-12-10

    Whereas there is growing interest in producing biomaterials containing coiled-coils, relatively few studies have made use of naturally occurring fibrous proteins. In this study, we have characterized fibrous proteins used by mother praying mantises to produce an extensive covering for their eggs called an ootheca and demonstrate the production of artificial ootheca using recombinantly produced proteins. Examination of natural oothecae by infrared spectroscopy and solid-state nuclear magnetic resonance revealed the material to consist of proteins organized predominately as coiled-coils. Two structural proteins, Mantis Fibroin 1 and Mantis Fibroin 2, were identified in ootheca from each of three species. Between species, the primary sequences of both proteins had diverged considerably, but other features were tightly conserved, including low molecular weight, high abundance of Ala, Glu, Lys, and Ser, and a triblock-like architecture with extensive central coiled-coil domain. Mantis fibroin hydrophobic cores had an unusual composition containing high levels of alanine and aromatic residues. Recombinantly produced mantis fibroins folded into coiled-coils in solution and could be fabricated into solid materials with high coiled-coil content. The structural features of mantis fibroins and their straightforward recombinant production make them promising templates for the production of coiled-coil biomimetics materials.

  18. 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.

  19. A comparative study of flat coil and coil sensor for landslide detection

    NASA Astrophysics Data System (ADS)

    Sanjaya, Edi; Muslimin, Ahmad Novi; Djamal, Mitra; Suprijadi, Handayani, Gunawan; Ramli

    2016-03-01

    The landslide is one of the most costly catastrophic events in terms of human lives and infrastructure damage, thus an early warning monitoring for landslides becomes more and more important. Currently existing monitoring systems for early warning are available in terms of monolithic systems. This is a very cost-intensive way, considering installation as well as operational and personal expenses. We have been developing a landslide detection system based on flat coil and coil sensor. The flat coil element being developed is an inductive proximity sensor for detection mass of soil movement. The simple method of flat coil manufactures and low cost, is an attraction that is still inspired to develop flat coil sensors. Meanwhile, although it has a drawback in terms of their size, the coil sensor is still required in many fields due to their sensitivity and robustness. The simple method of coil manufacture and the materials are commonly available and low cost, is an attraction that is still inspired to develop induction coil sensors. A comparative study of alternative configuration of sensor based on flat coil elements and a coil in application to landslide detection has been discussed in this paper. The purpose of this comparison is to show the ideal conditions and the challenges for each sensor. Furthermore, a comparison between flat coil and coil sensor is presented.

  20. Structural characteristics of the redox-sensing coiled coil in the voltage-gated H+ channel.

    PubMed

    Fujiwara, Yuichiro; Takeshita, Kohei; Nakagawa, Atsushi; Okamura, Yasushi

    2013-06-21

    Oxidation is an important biochemical defense mechanism, but it also elicits toxicity; therefore, oxidation must be under strict control. In phagocytotic events in neutrophils, the voltage-gated H(+) (Hv) channel is a key regulator of the production of reactive oxygen species against invading bacteria. The cytoplasmic domain of the Hv channel forms a dimeric coiled coil underpinning a dimerized functional unit. Importantly, in the alignment of the coiled-coil core, a conserved cysteine residue forms a potential intersubunit disulfide bond. In this study, we solved the crystal structures of the coiled-coil domain in reduced, oxidized, and mutated (Cys → Ser) states. The crystal structures indicate that a pair of Cys residues forms an intersubunit disulfide bond dependent on the redox conditions. CD spectroscopy revealed that the disulfide bond increases the thermal stability of the coiled-coil protein. We also reveal that two thiol modifier molecules are able to bind to Cys in a redox-dependent manner without disruption of the dimeric coiled-coil assembly. Thus, the biochemical properties of the cytoplasmic coiled-coil domain in the Hv channel depend on the redox condition, which may play a role in redox sensing in the phagosome.

  1. 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.

  2. 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

  3. Role of the Simian Virus 5 Fusion Protein N-Terminal Coiled-Coil Domain in Folding and Promotion of Membrane Fusion

    PubMed Central

    West, Dava S.; Sheehan, Michael S.; Segeleon, Patrick K.; Dutch, Rebecca Ellis

    2005-01-01

    Formation of a six-helix bundle comprised of three C-terminal heptad repeat regions in antiparallel orientation in the grooves of an N-terminal coiled-coil is critical for promotion of membrane fusion by paramyxovirus fusion (F) proteins. We have examined the effect of mutations in four residues of the N-terminal heptad repeat in the simian virus 5 (SV5) F protein on protein folding, transport, and fusogenic activity. The residues chosen have previously been shown from study of isolated peptides to have differing effects on stability of the N-terminal coiled-coil and six-helix bundle (R. E. Dutch, G. P. Leser, and R. A. Lamb, Virology 254:147-159, 1999). The mutant V154M showed reduced proteolytic cleavage and surface expression, indicating a defect in intracellular transport, though this mutation had no effect when studied in isolated peptides. The mutation I137M, previously shown to lower thermostability of the six-helix bundle, resulted in an F protein which was properly processed and transported to the cell surface but which had reduced fusogenic activity. Finally, mutations at L140M and L161M, previously shown to disrupt α-helix formation of isolated N-1 peptides but not to affect six-helix bundle formation, resulted in F proteins that were properly processed. Interestingly, the L161M mutant showed increased syncytium formation and promoted fusion at lower temperatures than the wild-type F protein. These results indicate that interactions separate from formation of an N-terminal coiled-coil or six-helix bundle are important in the initial folding and transport of the SV5 F protein and that mutations that destabilize the N-terminal coiled-coil can result in stimulation of membrane fusion. PMID:15650180

  4. 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.

  5. Impact of PF and TF coils misalignment on toroidally asymmetric plasma error fields in TPX

    SciTech Connect

    Leuer, J.A.; Luxon, J.L.; Xu, M.F.; Antaya, T.A.

    1995-12-31

    Error fields from misalignment of the toroidal field (TF) and poloidal field (PF) coils in TPX are presented in terms of the outward normal B-field (B{sub {perpendicular}}), expanded in poloidal and toroidal harmonics (m, n), on a simulated, D-shaped, plasma flux surface. Results are reported for n = 1 toroidal mode number and low poloidal mode numbers, m, and for various displacements of the TF and PF coils. In particular, results are given for the m,n = 2,1 error field which interacts with the q = 2 surface to cause locked modes and loss of plasma performance. Based on existing experiments, maximum permissible field errors are 4 G for the 2,1 mode and 8 G for the n = 1; m = 1,3,4 modes. Results are presented for a rigid shift and rotation of a single TF coil and for a rigid, radial shift of each PF coil.

  6. Designed Coiled-Coil Peptides Inhibit the Type Three Secretion System of Enteropathogenic Escherichia coli

    PubMed Central

    Larzábal, Mariano; Mercado, Elsa C.; Vilte, Daniel A.; Salazar-González, Hector; Cataldi, Angel; Navarro-Garcia, Fernando

    2010-01-01

    Background Enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) are two categories of E. coli strains associated with human disease. A major virulence factor of both pathotypes is the expression of a type three secretion system (TTSS), responsible for their ability to adhere to gut mucosa causing a characteristic attaching and effacing lesion (A/E). The TTSS translocates effector proteins directly into the host cell that subvert mammalian cell biochemistry. Methods/Principal Findings We examined synthetic peptides designed to inhibit the TTSS. CoilA and CoilB peptides, both representing coiled-coil regions of the translocator protein EspA, and CoilD peptide, corresponding to a coiled–coil region of the needle protein EscF, were effective in inhibiting the TTSS dependent hemolysis of red blood cells by the EPEC E2348/69 strain. CoilA and CoilB peptides also reduced the formation of actin pedestals by the same strain in HEp-2 cells and impaired the TTSS-mediated protein translocation into the epithelial cell. Interestingly, CoilA and CoilB were able to block EspA assembly, destabilizing the TTSS and thereby Tir translocation. This blockage of EspA polymerization by CoilA or CoilB peptides, also inhibited the correct delivery of EspB and EspD as detected by immunoblotting. Interestingly, electron microscopy of bacteria incubated with the CoilA peptide showed a reduction of the length of EspA filaments. Conclusions Our data indicate that coiled-coil peptides can prevent the assembly and thus the functionality of the TTSS apparatus and suggest that these peptides could provide an attractive tool to block EPEC and EHEC pathogenesis. PMID:20140230

  7. 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.

  8. 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.

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. 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.

  14. 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…

  15. 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…

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Design description of the Large Coil Test Facility pulse-coil support and transport system

    SciTech Connect

    Queen, C.C.

    1981-01-01

    In order to simulate the transient fields which would be imposed on superconducting toroidal field coils in an operating tokamak reactor, the Large Coil Test Facility (LCTF) test stand includes a set of pulse coils. This set of pulse coils is designed to be moved from one test location to another within the LCTF vacuum vessel while the vessel is operating under vacuum and the test stand and test coils are at an operating temperature of 4.2K. This operating environment and the extremely high magnetic loads have necessitated some unique design features for the pulse coil support and transport system. The support structure for the pulse coil must react high overturning moments and axial loads induced on the pulse coil by the interaction of the pulse field with the field generated by the large test coils. These loads are reacted into the test stand support structure or spider frame by an arrangement of six pedestals and a support beam. In order to move the pulse coil set from one test location to another, the support beam containing the pulse coils must be driven across rollers mounted on the pedestals, then clamped securely to react the loads. Because these operations must be performed in a vacuum environment at cryogenic tmperature, special consideration was given to component design.

  4. 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.

  5. 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.

  6. 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

  7. Coils and tubes releasing heparin. Studies on a new vascular graft prototype.

    PubMed

    Aldenhoff, Yvette B J; Knetsch, Menno L W; Hanssen, Johannes H L; Lindhout, Theo; Wielders, Simone J H; Koole, L H Leo H

    2004-07-01

    Coiled metallic guidewires find widespread use, for instance in interventional cardiology. It is known that release of heparin from the surface of guidewires is advantageous to prevent formation of thrombotic emboli. New coiled tubular structures, having larger inner and outer diameter as compared to guidewires, are presented. In theory these tubes can be used as interposition vascular grafts. Ten coiled tubes with an internal diameter of 690 microm were made. Five different adherent polymeric coatings with increasing hydrophilicity were used. Five tubes contained heparin in the coating and the other five were unheparinised controls. The five tubes containing heparin were studied with respect to heparin release in vitro (amount released, kinetics), and immobilised heparin that is exposed at the surface. All tubes were studied with a direct cell contact assay using 3T3 mouse fibroblast cells, a dynamic thrombin generation test, and endothelial cell growth onto the coils. It was found that the heparinised tubes lead to very little thrombin formation. It is argued that this is due to heparin that is immobilised and exposed at the inner surface of such tubes. Furthermore the coils showed to be cytocompatible and endothelial cells adhere and proliferate well onto the coils. This concept is believed to hold promise for further development of small vascular grafts.

  8. Facilitated diffusion with DNA coiling

    PubMed Central

    Lomholt, Michael A.; van den Broek, Bram; Kalisch, Svenja-Marei J.; Wuite, Gijs J. L.; Metzler, Ralf

    2009-01-01

    When DNA-binding proteins search for their specific binding site on a DNA molecule they alternate between linear 1-dimensional diffusion along the DNA molecule, mediated by nonspecific binding, and 3-dimensional volume excursion events between successive dissociation from and rebinding to DNA. If the DNA molecule is kept in a straight configuration, for instance, by optical tweezers, these 3-dimensional excursions may be divided into long volume excursions and short hops along the DNA. These short hops correspond to immediate rebindings after dissociation such that a rebinding event to the DNA occurs at a site that is close to the site of the preceding dissociation. When the DNA molecule is allowed to coil up, immediate rebinding may also lead to so-called intersegmental jumps, i.e., immediate rebindings to a DNA segment that is far away from the unbinding site when measured in the chemical distance along the DNA, but close by in the embedding 3-dimensional space. This effect is made possible by DNA looping. The significance of intersegmental jumps was recently demonstrated in a single DNA optical tweezers setup. Here we present a theoretical approach in which we explicitly take the effect of DNA coiling into account. By including the spatial correlations of the short hops we demonstrate how the facilitated diffusion model can be extended to account for intersegmental jumping at varying DNA densities. It is also shown that our approach provides a quantitative interpretation of the experimentally measured enhancement of the target location by DNA-binding proteins. PMID:19420219

  9. Theoretical and computational studies of entangled rod-coil block copolymer diffusion

    NASA Astrophysics Data System (ADS)

    Wang, Muzhou; Alexander-Katz, Alfredo; Olsen, B. D.

    2012-02-01

    Despite continued interest in the thermodynamics of rod-coil block copolymers for functional nanostructured materials in organic electronics and biomaterials, relatively few studies have investigated the dynamics of these systems which are important for understanding diffusion, mechanics, and self-assembly kinetics. Here, the diffusion of coil-rod-coil block copolymers through entangled melts is simulated using the Kremer-Grest molecular dynamics model, demonstrating that the mismatch between the curvature of the rod and coil blocks results in dramatically slower reptation through the entanglement tube. For rod lengths near the tube diameter, this hindered diffusion is explained by a local curvature-dependent free energy penalty produced by the curvature mismatch, resulting in a rough energy surface as the rod moves along the tube contour. Compared to coil homopolymers which reptate freely along the tube, rod-coil block copolymers undergo an activated diffusion process which is considerably slower as the rod length increases. For large rods, diffusion of the rod through the tube only occurs when the coil blocks occupy straight entanglement tubes, which requires ``arm retraction'' as the dominant relaxation mechanism.

  10. 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).

  11. 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.

  12. 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

  13. 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.

  14. Orientation and Oligomerization Specificity of the Bcr Coiled-Coil Oligomerization Domain†

    PubMed Central

    Taylor, Christina M.; Keating, Amy E.

    2008-01-01

    The Bcr oligomerization domain, from the Bcr-Abl oncoprotein, is an attractive therapeutic target for treating leukemias because it is required for cellular transformation. The domain homodimerizes via an antiparallel coiled coil with an adjacent short, helical swap domain. Inspection of the coiled-coil sequence does not reveal obvious determinants of helix-orientation specificity, raising the possibility that the antiparallel orientation preference and/or the dimeric oligomerization state are due to interactions of the swap domains. To better understand how structural specificity is encoded in Bcr, coiled-coil constructs containing either an N- or C-terminal cysteine were synthesized without the swap domain. When crosslinked to adopt exclusively parallel or antiparallel orientations, these showed similar circular dichroism spectra. Both constructs formed coiled-coil dimers, but the antiparallel construct was ~16 °C more stable than the parallel to thermal denaturation. Equilibrium disulfide-exchange studies confirmed that the isolated coiled-coil homodimer shows a very strong preference for the antiparallel orientation. We conclude that the orientation and oligomerization preferences of Bcr are not caused by the presence of the swap domains, but rather are directly encoded in the coiled-coil sequence. We further explored possible determinants of structural specificity by mutating residues in the d position of the coiled-coil core. Some of the mutations caused a change in orientation specificity, and all of the mutations led to the formation of higher-order oligomers. In the absence of the swap domain, these residues play an important role in disfavoring alternate states and are especially important for encoding dimeric oligomerization specificity. PMID:16331985

  15. 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.

  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. Attenuation Correction for Flexible Magnetic Resonance Coils in Combined Magnetic Resonance/Positron Emission Tomography Imaging

    PubMed Central

    Eldib, Mootaz; Bini, Jason; Calcagno, Claudia; Robson, Philip M.; Mani, Venkatesh; Fayad, Zahi A.

    2014-01-01

    Introduction Attenuation correction for magnetic resonance (MR) coils is a new challenge that came about with the development of combined MR and positron emission tomography (PET) imaging. This task is difficult because such coils are not directly visible on either PET or MR acquisitions with current combined scanners and are therefore not easily localized in the field of view. This issue becomes more evident when trying to localize flexible MR coils (eg, cardiac or body matrix coil) that change position and shape from patient to patient and from one imaging session to another. In this study, we proposed a novel method to localize and correct for the attenuation and scatter of a flexible MR cardiac coil, using MR fiducial markers placed on the surface of the coil to allow for accurate registration of a template computed tomography (CT)–based attenuation map. Materials and Methods To quantify the attenuation properties of the cardiac coil, a uniform cylindrical water phantom injected with 18F-fluorodeoxyglucose (18F-FDG) was imaged on a sequential MR/PET system with and without the flexible cardiac coil. After establishing the need to correct for the attenuation of the coil, we tested the feasibility of several methods to register a precomputed attenuation map to correct for the attenuation. To accomplish this, MR and CT visible markers were placed on the surface of the cardiac flexible coil. Using only the markers as a driver for registration, the CT image was registered to the reference image through a combination of rigid and deformable registration. The accuracy of several methods was compared for the deformable registration, including B-spline, thin-plate spline, elastic body spline, and volume spline. Finally, we validated our novel approach both in phantom and patient studies. Results The findings from the phantom experiments indicated that the presence of the coil resulted in a 10% reduction in measured 18F-FDG activity when compared with the phantom

  18. Attenuation correction for flexible magnetic resonance coils in combined magnetic resonance/positron emission tomography imaging.

    PubMed

    Eldib, Mootaz; Bini, Jason; Calcagno, Claudia; Robson, Philip M; Mani, Venkatesh; Fayad, Zahi A

    2014-02-01

    Attenuation correction for magnetic resonance (MR) coils is a new challenge that came about with the development of combined MR and positron emission tomography (PET) imaging. This task is difficult because such coils are not directly visible on either PET or MR acquisitions with current combined scanners and are therefore not easily localized in the field of view. This issue becomes more evident when trying to localize flexible MR coils (eg, cardiac or body matrix coil) that change position and shape from patient to patient and from one imaging session to another. In this study, we proposed a novel method to localize and correct for the attenuation and scatter of a flexible MR cardiac coil, using MR fiducial markers placed on the surface of the coil to allow for accurate registration of a template computed tomography (CT)-based attenuation map. To quantify the attenuation properties of the cardiac coil, a uniform cylindrical water phantom injected with 18F-fluorodeoxyglucose (18F-FDG) was imaged on a sequential MR/PET system with and without the flexible cardiac coil. After establishing the need to correct for the attenuation of the coil, we tested the feasibility of several methods to register a precomputed attenuation map to correct for the attenuation. To accomplish this, MR and CT visible markers were placed on the surface of the cardiac flexible coil. Usi