Effective arrangement of separated transmit-only/receive-only RF coil for improvement of B1 homogeneity at 7 Tesla

Science.gov (United States)

Im, Geun Ho; Seo, Jeong-Hoon; Kim, Kyoung-Nam; Heo, Phil; Chung, Julius Juhyun; Jang, Moon-Sun; Lee, Jung Hee; Kim, Jae-Hun; Kim, Sun I.

2014-09-01

This article presents an effective arrangement with shifted transmit (Tx)-only and receive (Rx)-only (TORO) radiofrequency (RF) coils in a single-channel surface coil for improving the magnetic flux ( B 1) homogeneity in an ultra-high field (UHF) magnetic resonance imaging (MRI) scanner. The proposed new methodology for the coil arrangement using the shifted TORO RF coils was demonstrated for coils with 50-mm, 100-mm, and 150-mm-square surfaces and the results were compared to those for general Tx/Rx surface coils with the same dimensions. The computational analysis indicated that a homogeneous B1 field was achieved when the Rx-only coil was shifted in the two-dimensional xy-plane away from the Tx-only coils. Because the proposed coil configuration provides a unique opportunity for increasing the B 1 homogeneity, this feature is likely to increase the feasibility via new coil arrangements of UHF surface design and fabrication.

Using a whole-body 31P birdcage transmit coil and 16-element receive array for human cardiac metabolic imaging at 7T.

Directory of Open Access Journals (Sweden)

Ladislav Valkovič

Full Text Available Cardiac phosphorus magnetic resonance spectroscopy (31P-MRS provides unique insight into the mechanisms of heart failure. Yet, clinical applications have been hindered by the restricted sensitivity of the surface radiofrequency-coils normally used. These permit the analysis of spectra only from the interventricular septum, or large volumes of myocardium, which may not be meaningful in focal disease. Löring et al. recently presented a prototype whole-body (52 cm diameter transmit/receive birdcage coil for 31P at 7T. We now present a new, easily-removable, whole-body 31P transmit radiofrequency-coil built into a patient-bed extension combined with a 16-element receive array for cardiac 31P-MRS.A fully-removable (55 cm diameter birdcage transmit coil was combined with a 16-element receive array on a Magnetom 7T scanner (Siemens, Germany. Electro-magnetic field simulations and phantom tests of the setup were performed. In vivo maps of B1+, metabolite signals, and saturation-band efficiency were acquired across the torsos of eight volunteers.The combined (volume-transmit, local receive array setup increased signal-to-noise ratio 2.6-fold 10 cm below the array (depth of the interventricular septum compared to using the birdcage coil in transceiver mode. The simulated coefficient of variation for B1+ of the whole-body coil across the heart was 46.7% (surface coil 129.0%; and the in vivo measured value was 38.4%. Metabolite images of 2,3-diphosphoglycerate clearly resolved the ventricular blood pools, and muscle tissue was visible in phosphocreatine (PCr maps. Amplitude-modulated saturation bands achieved 71±4% suppression of phosphocreatine PCr in chest-wall muscles. Subjects reported they were comfortable.This easy-to-assemble, volume-transmit, local receive array coil combination significantly improves the homogeneity and field-of-view for metabolic imaging of the human heart at 7T.

32-channel 3 Tesla receive-only phased-array head coil with soccer-ball element geometry.

Science.gov (United States)

Wiggins, G C; Triantafyllou, C; Potthast, A; Reykowski, A; Nittka, M; Wald, L L

2006-07-01

A 32-channel 3T receive-only phased-array head coil was developed for human brain imaging. The helmet-shaped array was designed to closely fit the head with individual overlapping circular elements arranged in patterns of hexagonal and pentagonal symmetry similar to that of a soccer ball. The signal-to-noise ratio (SNR) and noise amplification (g-factor) in accelerated imaging applications were quantitatively evaluated in phantom and human images and compared with commercially available head coils. The 32-channel coil showed SNR gains of up to 3.5-fold in the cortex and 1.4-fold in the corpus callosum compared to a (larger) commercial eight-channel head coil. The experimentally measured g-factor performance of the helmet array showed significant improvement compared to the eight-channel array (peak g-factor 59% and 26% of the eight-channel values for four- and fivefold acceleration). The performance of the arrays is demonstrated in high-resolution and highly accelerated brain images. Copyright (c) 2006 Wiley-Liss, Inc.

Automatic treatment of multiple wound coils in 3D finite element problems including multiply connected regions

Energy Technology Data Exchange (ETDEWEB)

Leonard, P.J.; Lai, H.C.; Eastham, J.F.; Al-Akayshee, Q.H. [Univ. of Bath (United Kingdom)

1996-05-01

This paper describes an efficient scheme for incorporating multiple wire wound coils into 3D finite element models. The scheme is based on the magnetic scalar representation with an additional basis for each coil. There are no restrictions on the topology of coils with respect to ferromagnetic and conductor regions. Reduced scalar regions and cuts are automatically generated.

A new type of coil structure called pan-shaped coil of wireless charging system based on magnetic resonance

Science.gov (United States)

Yue, Z. K.; Liu, Z. Z.; Hou, Y. J.; Zeng, H.; Liang, L. H.; Cui, S.

2017-11-01

The problem that misalignment between the transmitting coil and the receiving coil significantly impairs the transmission power and efficiency of the system has been attached more and more attention. In order to improve the uniformity of the magnetic field between the two coils to solve this problem, a new type of coil called pan-shaped coil is proposed. Three-dimension simulation models of the planar-core coil and the pan-shaped coil are established using Ansoft Maxwell software. The coupling coefficient between the transmitting coil and the receiving coil is obtained by simulating the magnetic field with the receiving coil misalignment or not. And the maximum percentage difference strength along the radial direction which is defined as the magnetic field uniformity factor is calculated. According to the simulation results of the two kinds of coil structures, it is found that the new type of coil structure can obviously improve the uniformity of the magnetic field, coupling coefficient and power transmission properties between the transmitting coil and the receiving coil.

CCHMM_PROF: a HMM-based coiled-coil predictor with evolutionary information

DEFF Research Database (Denmark)

Bartoli, Lisa; Fariselli, Piero; Krogh, Anders

2009-01-01

tools are available for predicting coiled-coil domains in protein sequences, including those based on position-specific score matrices and machine learning methods. RESULTS: In this article, we introduce a hidden Markov model (CCHMM_PROF) that exploits the information contained in multiple sequence...... alignments (profiles) to predict coiled-coil regions. The new method discriminates coiled-coil sequences with an accuracy of 97% and achieves a true positive rate of 79% with only 1% of false positives. Furthermore, when predicting the location of coiled-coil segments in protein sequences, the method reaches...

An 8-channel transceiver 7-channel receive RF coil setup for high SNR ultrahigh-field MRI of the shoulder at 7T.

Science.gov (United States)

Rietsch, Stefan H G; Pfaffenrot, Viktor; Bitz, Andreas K; Orzada, Stephan; Brunheim, Sascha; Lazik-Palm, Andrea; Theysohn, Jens M; Ladd, Mark E; Quick, Harald H; Kraff, Oliver

2017-12-01

In this work, we present an 8-channel transceiver (Tx/Rx) 7-channel receive (Rx) radiofrequency (RF) coil setup for 7 T ultrahigh-field MR imaging of the shoulder. A C-shaped 8-channel Tx/Rx coil was combined with an anatomically close-fitting 7-channel Rx-only coil. The safety and performance parameters of this coil setup were evaluated on the bench and in phantom experiments. The 7 T MR imaging performance of the shoulder RF coil setup was evaluated in in vivo measurements using a 3D DESS, a 2D PD-weighted TSE sequence, and safety supervision based on virtual observation points. Distinct SNR gain and acceleration capabilities provided by the additional 7-channel Rx-only coil were demonstrated in phantom and in vivo measurements. The power efficiency indicated good performance of each channel and a maximum B 1 + of 19 μT if the hardware RF power limits of the MR system were exploited. MR imaging of the shoulder was demonstrated with clinically excellent image quality and submillimeter spatial resolution. The presented 8-channel transceiver 7-channel receive RF coil setup was successfully applied for in vivo 7 T MRI of the shoulder providing a clear SNR gain vs the transceiver array without the additional receive array. Homogeneous images across the shoulder region were obtained using 8-channel subject-specific phase-only RF shimming. © 2017 American Association of Physicists in Medicine.

The effect of receiver coil orientations on the imaging performance of magnetic induction tomography

Science.gov (United States)

Gürsoy, D.; Scharfetter, H.

2009-10-01

Magnetic induction tomography is an imaging modality which aims to reconstruct the conductivity distribution of the human body. It uses magnetic induction to excite the body and an array of sensor coils to detect the perturbations in the magnetic field. Up to now, much effort has been expended with the aim of finding an efficient coil configuration to extend the dynamic range of the measured signal. However, the merits of different sensor orientations on the imaging performance have not been studied in great detail so far. Therefore, the aim of the study is to fill the void of a systematic investigation of coil orientations on the reconstruction quality of the designs. To this end, a number of alternative receiver array designs with different coil orientations were suggested and the evaluations of the designs were performed based on the singular value decomposition. A generalized class of quality measures, the subclasses of which are linked to both the spatial resolution and uncertainty measures, was used to assess the performance on the radial and axial axes of a cylindrical phantom. The detectability of local conductivity perturbations in the phantom was explored using the reconstructed images. It is possible to draw the conclusion that the proper choice of the coil orientations significantly influences the number of usable singular vectors and accordingly the stability of image reconstruction, although the effect of increased stability on the quality of the reconstructed images was not of paramount importance due to the reduced independent information content of the associated singular vectors.

The effect of receiver coil orientations on the imaging performance of magnetic induction tomography

International Nuclear Information System (INIS)

Gürsoy, D; Scharfetter, H

2009-01-01

Magnetic induction tomography is an imaging modality which aims to reconstruct the conductivity distribution of the human body. It uses magnetic induction to excite the body and an array of sensor coils to detect the perturbations in the magnetic field. Up to now, much effort has been expended with the aim of finding an efficient coil configuration to extend the dynamic range of the measured signal. However, the merits of different sensor orientations on the imaging performance have not been studied in great detail so far. Therefore, the aim of the study is to fill the void of a systematic investigation of coil orientations on the reconstruction quality of the designs. To this end, a number of alternative receiver array designs with different coil orientations were suggested and the evaluations of the designs were performed based on the singular value decomposition. A generalized class of quality measures, the subclasses of which are linked to both the spatial resolution and uncertainty measures, was used to assess the performance on the radial and axial axes of a cylindrical phantom. The detectability of local conductivity perturbations in the phantom was explored using the reconstructed images. It is possible to draw the conclusion that the proper choice of the coil orientations significantly influences the number of usable singular vectors and accordingly the stability of image reconstruction, although the effect of increased stability on the quality of the reconstructed images was not of paramount importance due to the reduced independent information content of the associated singular vectors

High-resolution magnetic resonance imaging of the anal sphincter using a dedicated endoanal receiver coil

International Nuclear Information System (INIS)

DeSouza, N.M.; Williams, A.D.; Gilderdale, D.J.

1999-01-01

The use of a surface coil in MR imaging improves signal-to-noise ratio of adjacent tissues of interest. We therefore devised an endoanal receiver coil for imaging the anal sphincter. The probe is solid and re-usable: it comprises a saddle geometry receiver with integral tuning, matching and decoupling. It is placed in the anal canal and immobilised externally. Both in vitro and in vivo normal anatomy is identified. The mucosa is high signal intensity, the submucosa low signal intensity, the internal sphincter uniformly high signal intensity and the external sphincter low signal intensity on T1- and T2-weighted images. In females, the transverse perineal muscle bridges the inferior part of the external sphincter anteriorly. In perianal sepsis, collections and the site of the endoanal opening are identified. In early-onset fecal incontinence following obstetric trauma/surgery, focal sphincter defects are demonstrated; in late-onset fecal incontinence external sphincter atrophy is seen. In fecally incontinent patients with scleroderma, forward deviation of the anterior sphincter musculature with descent of rectal air and feces into the anal canal is noted. The extent of sphincter invasion is assessed in low rectal tumours. In children with congenital anorectal anomalies, abnormalities of the muscle components are defined using smaller-diameter coils. Such information is invaluable in the assessment and surgical planning of patients with a variety of anorectal pathologies. (orig.)

Molecular basis of coiled-coil oligomerization-state specificity.

Science.gov (United States)

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.

Three-phase receiving coil of wireless power transmission system for gastrointestinal robot

Science.gov (United States)

Jia, Z. W.; Jiang, T.; Liu, Y.

2017-11-01

Power shortage is the bottleneck for the wide application of gastrointestinal (GI) robot. Owing to the limited volume and free change of orientation of the receiving set in GI trace, the optimal of receiving set is the key point to promote the transmission efficiency of wireless power transmission system. A new type of receiving set, similar to the winding of three-phase asynchronous motor, is presented and compared with the original three-dimensional orthogonal coil. Considering the given volume and the space utilization ratio, the three-phase and the three-orthogonal ones are the parameters which are optimized and compared. Both the transmission efficiency and stability are analyzed and verified by in vitro experiments. Animal experiments show that the new one could provide at least 420 mW power in volume of Φ11 × 13mm with a uniformity of 78.3% for the GI robot.

On-coil multiple channel transmit system based on class-D amplification and pre-amplification with current amplitude feedback.

Science.gov (United States)

Gudino, Natalia; Heilman, Jeremiah A; Riffe, Matthew J; Heid, Oliver; Vester, Markus; Griswold, Mark A

2013-07-01

A complete high-efficiency transmit amplifier unit designed to be implemented in on-coil transmit arrays is presented. High power capability, low power dissipation, scalability, and cost minimization were some of the requirements imposed to the design. The system is composed of a current mode class-D amplifier output stage and a voltage mode class-D preamplification stage. The amplitude information of the radio frequency pulse was added through a customized step-down DC-DC converter with current amplitude feedback that connects to the current mode class-D stage. Benchtop measurements and imaging experiments were carried out to analyze system performance. Direct control of B1 was possible and its load sensitivity was reduced to less than 10% variation from unloaded to full loaded condition. When using the amplifiers in an array configuration, isolation above 20 dB was achieved between neighboring coils by the amplifier decoupling method. High output current operation of the transmitter was proved on the benchtop through output power measurements and in a 1.5T scanner through flip angle quantification. Finally, single and multiple channel excitations with the new hardware were demonstrated by receiving signal with the body coil of the scanner. Copyright © 2012 Wiley Periodicals, Inc.

High-resolution magnetic resonance imaging of the anal sphincter using a dedicated endoanal receiver coil

Energy Technology Data Exchange (ETDEWEB)

DeSouza, N.M.; Williams, A.D.; Gilderdale, D.J. [Dept. of Radiology, Imperial College School of Medicine, London (United Kingdom)

1999-04-01

The use of a surface coil in MR imaging improves signal-to-noise ratio of adjacent tissues of interest. We therefore devised an endoanal receiver coil for imaging the anal sphincter. The probe is solid and re-usable: it comprises a saddle geometry receiver with integral tuning, matching and decoupling. It is placed in the anal canal and immobilised externally. Both in vitro and in vivo normal anatomy is identified. The mucosa is high signal intensity, the submucosa low signal intensity, the internal sphincter uniformly high signal intensity and the external sphincter low signal intensity on T1- and T2-weighted images. In females, the transverse perineal muscle bridges the inferior part of the external sphincter anteriorly. In perianal sepsis, collections and the site of the endoanal opening are identified. In early-onset fecal incontinence following obstetric trauma/surgery, focal sphincter defects are demonstrated; in late-onset fecal incontinence external sphincter atrophy is seen. In fecally incontinent patients with scleroderma, forward deviation of the anterior sphincter musculature with descent of rectal air and feces into the anal canal is noted. The extent of sphincter invasion is assessed in low rectal tumours. In children with congenital anorectal anomalies, abnormalities of the muscle components are defined using smaller-diameter coils. Such information is invaluable in the assessment and surgical planning of patients with a variety of anorectal pathologies. (orig.) With 15 figs., 26 refs.

Water cooling coil

Energy Technology Data Exchange (ETDEWEB)

Suzuki, S; Ito, Y; Kazawa, Y

1975-02-05

Object: To provide a water cooling coil in a toroidal nuclear fusion device, in which coil is formed into a small-size in section so as not to increase dimensions, weight or the like of machineries including the coil. Structure: A conductor arranged as an outermost layer of a multiple-wind water cooling coil comprises a hollow conductor, which is directly cooled by fluid, and as a consequence, a solid conductor disposed interiorly thereof is cooled indirectly.

Golgi coiled-coil proteins contain multiple binding sites for Rab family G proteins

NARCIS (Netherlands)

Sinka, Rita; Gillingham, Alison K.; Kondylis, Vangelis; Munro, Sean

2008-01-01

Vesicles and other carriers destined for the Golgi apparatus must be guided to the correct cisternae. Golgins, long coiled-coil proteins that localize to particular Golgi subdomains via their C termini, are candidate regulators of vesicle sorting. In this study, we report that the GRIP domain

Novel 16-channel receive coil array for accelerated upper airway MRI at 3 Tesla.

Science.gov (United States)

Kim, Yoon-Chul; Hayes, Cecil E; Narayanan, Shrikanth S; Nayak, Krishna S

2011-06-01

Upper airway MRI can provide a noninvasive assessment of speech and swallowing disorders and sleep apnea. Recent work has demonstrated the value of high-resolution three-dimensional imaging and dynamic two-dimensional imaging and the importance of further improvements in spatio-temporal resolution. The purpose of the study was to describe a novel 16-channel 3 Tesla receive coil that is highly sensitive to the human upper airway and investigate the performance of accelerated upper airway MRI with the coil. In three-dimensional imaging of the upper airway during static posture, 6-fold acceleration is demonstrated using parallel imaging, potentially leading to capturing a whole three-dimensional vocal tract with 1.25 mm isotropic resolution within 9 sec of sustained sound production. Midsagittal spiral parallel imaging of vocal tract dynamics during natural speech production is demonstrated with 2 × 2 mm(2) in-plane spatial and 84 ms temporal resolution. Copyright © 2010 Wiley-Liss, Inc.

Three-dimensional magnetic nanoparticle imaging using small field gradient and multiple pickup coils

Energy Technology Data Exchange (ETDEWEB)

Sasayama, Teruyoshi, E-mail: sasayama@sc.kyushu-u.ac.jp; Tsujita, Yuya; Morishita, Manabu; Muta, Masahiro; Yoshida, Takashi; Enpuku, Keiji

2017-04-01

We propose a magnetic particle imaging (MPI) method based on third harmonic signal detection using a small field gradient and multiple pickup coils. First, we developed a system using two pickup coils and performed three-dimensional detection of two magnetic nanoparticle (MNP) samples, which were spaced 15 mm apart. In the experiments, an excitation field strength of 1.6 mT was used at an operating frequency of 3 kHz. A DC gradient field with a typical value of 0.2 T/m was also used to produce the so-called field-free line. A third harmonic signal generated by the MNP samples was detected using the two pickup coils, and the samples were then mechanically scanned to obtain field maps. The field maps were subsequently analyzed using the nonnegative least squares method to obtain three-dimensional position information for the MNP samples. The results show that the positions of the two MNP samples were estimated with good accuracy, despite the small field gradient used. Further improvement in MPI performance will be achieved by increasing the number of pickup coils used. - Highlights: • 3D magnetic particle imaging system combining field-free line and two pickup coils. • Imaging method based on third harmonic signal detection and small field gradient. • Nonnegative least squares method for 3D magnetic nanoparticle image reconstruction. • High spatial resolution despite use of small field gradient.

Extended Monopole antenna Array with individual Shield (EMAS) coil: An improved monopole antenna design for brain imaging at 7 tesla MRI.

Science.gov (United States)

Woo, Myung-Kyun; Hong, Suk-Min; Lee, Jongho; Kang, Chang-Ki; Park, Sung-Yeon; Son, Young-Don; Kim, Young-Bo; Cho, Zang-Hee

2016-06-01

To propose a new Extended Monopole antenna Array with individual Shields (EMAS) coil that improves the B1 field coverage and uniformity along the z-direction. To increase the spatial coverage of Monopole antenna Array (MA) coil, each monopole antenna was shielded and extended in length. Performance of this new coil, which is referred to as EMAS coil, was compared with the original MA coil and an Extended Monopole antenna Array coil with no shield (EMA). For comparison, flip angle, signal-to-noise ratio (SNR), and receive sensitivity maps were measured at multiple regions of interest (ROIs) in the brain. The EMAS coil demonstrated substantially larger flip angle and receive sensitivity than the MA and EMA coils in the inferior aspect of the brain. In the brainstem ROI, for example, the flip angle in the EMAS coil was increased by 45.5% (or 60.0%) and the receive sensitivity was increased by 26.9% (or 14.9%), resulting in an SNR gain of 84.8% (or 76.3%) when compared with the MA coil (or EMA). The EMAS coil provided 25.7% (or 24.4%) more uniform B1+ field distribution compared with the MA (or EMA) coil in sagittal. The EMAS coil successfully extended the imaging volume in lower part of the brain. Magn Reson Med 75:2566-2572, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Misalignment tolerable coil structure for biomedical applications with wireless power transfer.

Science.gov (United States)

Chow, Jeff P W; Chen, Nan; Chung, Henry S H; Chan, Leanne L H

2013-01-01

Coil-misalignment is one of the major hurdles for inductively coupled wireless power transfer in applications like retinal prosthesis. Weak magnetic flux linkage due to coil misalignments would significantly impair the power efficiency. A novel receiver configuration with high misalignment tolerance is presented in this paper. The proposed receiver is composed of two receiver coils placed orthogonally, so as to reduce the variation of mutual inductance between transmitting and receiving coils under misalignment conditions. Three different receiver coil structures are analyzed and compared using the same length of wire. Theoretical predictions have been confirmed with measurement results.

Omnidirectional Wireless Power Transfer System Based on Rotary Transmitting Coil for Household Appliances

Directory of Open Access Journals (Sweden)

Gongjun Liu

2018-04-01

Full Text Available An omnidirectional magnetically coupled resonant wireless power transfer (WPT system based on rotary transmitting coil is presented. The proposed scheme can ease the variations of the transfer efficiency and output power caused by the deviation of transfer direction, and improve the unbalanced power distribution phenomenon between the receivers, which are still not fully achieved in current WPT systems. The modified coupled-mode model is built first to describe the non-rotary multi-receiver WPT system. The analysis indicates that the transfer efficiency and output power of the system can be expressed as functions of the deviation angle between the transmitting coil and receiving coil, which has a non-negligible influence on the system performances. Then, the modified high order coupled-mode model containing time-varying parameters about the deviation angle is derived for the proposed omnidirectional WPT system. Theoretical analysis and simulated results indicate that this system can transfer power to multiple receivers around the transmitter synchronously and evenly, which is very suitable for wireless charging for household appliances indoors. The scheme feasibility and theoretical analysis are verified by experimental results.

A Two-dimensional Sixteen Channel Transmit/Receive Coil Array for Cardiac MRI at 7.0 Tesla: Design, Evaluation and Application

Science.gov (United States)

Thalhammer, Christof; Renz, Wolfgang; Winter, Lukas; Hezel, Fabian; Rieger, Jan; Pfeiffer, Harald; Graessl, Andreas; Seifert, Frank; Hoffmann, Werner; von Knobelsdorff-Brenkenhoff, Florian; Tkachenko, Valeriy; Schulz-Menger, Jeanette; Kellman, Peter; Niendorf, Thoralf

2012-01-01

Purpose To design, evaluate and apply a two-dimensional 16 channel transmit/receive coil array tailored for cardiac MRI at 7.0 Tesla. Material and Methods The cardiac coil array consists of 2 sections each using 8 elements arranged in a 2 × 4 array. RF safety was validated by SAR simulations. Cardiac imaging was performed using 2D CINE FLASH imaging, T2* mapping and fat-water separation imaging. The characteristics of the coil array were analyzed including parallel imaging performance, left ventricular chamber quantification and overall image quality. Results RF characteristics were found to be appropriate for all subjects included in the study. The SAR values derived from the simulations fall well in the limits of legal guidelines. The baseline SNR advantage at 7.0 T was put to use to acquire 2D CINE images of the heart with a very high spatial resolution of (1 × 1 × 4) mm3. The proposed coil array supports 1D acceleration factors of up to R=4 without impairing image quality significantly. Conclusions The 16 channel TX/RX coil has the capability to acquire high contrast and high spatial resolution images of the heart at 7.0 Tesla. PMID:22706727

Tracking method of small receiver coil using MR scanner

International Nuclear Information System (INIS)

Onogi, Shinya; Liao, Hongen; Kobayashi, Etsuko; Sakuma, Ichiro; Watanabe, Sigeru

2007-01-01

MR guided surgery is quite effective in realizing accurate and safe minimally invasive surgery (MIS). The combination of intra-operative MRI, surgical navigation system, and surgical robot should be of practical use in the field of MIS in the future. When we use flexible endoscope type robotic manipulator, the position and the orientation of the tip point of the flexible forceps should be navigated and controlled by a robotic manipulator. However, the conventional position sensor can not be used because of the strong magnetic field and the limited workspace. We propose a novel tracking method named extended active tracking (EAT), which is based on the active tracking algorithm. EAT can measure the position and the orientation of the tracking coils synchronically. The principle of EAT is three points measurement by three series inductance. We can calculate the orientation of three coils using the measured 3-D positions of coils. In this paper, three experiments was conducted to evaluate the basic performance of the EAT. First experiment is the flip angle adjustment for the reduction of background noise, which is caused by the proton around each inductance. The experimental results shown that the inductance positions could be clearly observed without background noise at 6-deg flip angle with nuclear magnetic resonance (NMR) signal peaks. Second experiment is the reproducibility evaluation. The fluctuation of measurement position and orientation were less than 0.3 mm (SD) and 1.0 deg (SD) at various positions and orientations. And standard deviation of the distance between the inductances at various positions and orientations is less than resolution (0.78 mm). Third experiment is an accuracy evaluation. The position measurement accuracy was 0.39 mm (RMS) using an optical tracking device. The orientation measurement accuracy was 3.5 deg (RMS) when the tracking coil was rotated 30 degree. Evaluation result suggests that EAT is possible to be used inside a patient body

Signal-to-noise ratio and MR tissue parameters in human brain imaging at 3, 7, and 9.4 tesla using current receive coil arrays.

Science.gov (United States)

Pohmann, Rolf; Speck, Oliver; Scheffler, Klaus

2016-02-01

Relaxation times, transmit homogeneity, signal-to-noise ratio (SNR) and parallel imaging g-factor were determined in the human brain at 3T, 7T, and 9.4T, using standard, tight-fitting coil arrays. The same human subjects were scanned at all three field strengths, using identical sequence parameters and similar 31- or 32-channel receive coil arrays. The SNR of three-dimensional (3D) gradient echo images was determined using a multiple replica approach and corrected with measured flip angle and T2 (*) distributions and the T1 of white matter to obtain the intrinsic SNR. The g-factor maps were derived from 3D gradient echo images with several GRAPPA accelerations. As expected, T1 values increased, T2 (*) decreased and the B1 -homogeneity deteriorated with increasing field. The SNR showed a distinctly supralinear increase with field strength by a factor of 3.10 ± 0.20 from 3T to 7T, and 1.76 ± 0.13 from 7T to 9.4T over the entire cerebrum. The g-factors did not show the expected decrease, indicating a dominating role of coil design. In standard experimental conditions, SNR increased supralinearly with field strength (SNR ∼ B0 (1.65) ). To take full advantage of this gain, the deteriorating B1 -homogeneity and the decreasing T2 (*) have to be overcome. © 2015 Wiley Periodicals, Inc.

Estimating achievable signal-to-noise ratios of MRI transmit-receive coils from radiofrequency power measurements: applications in quality control

International Nuclear Information System (INIS)

Redpath, T.W.

2000-01-01

The inverse relationship between the radiofrequency (RF) power needed to transmit a 90 deg. RF pulse, and the signal-to-noise ratio (SNR) available from a transmit-receive RF coil is well known. The theory is restated and a formula given for the signal-to-noise ratio from water, achievable from a single-shot MRI experiment, in terms of the net forward RF power needed for a rectangular 90 deg. RF pulse of known shape and duration. The result is normalized to a signal bandwidth of 1 Hz and a sample mass of 1 g. The RF power information needed is available on most commercial scanners, as it is used to calculate specific absorption rates for RF tissue heating. The achievable SNR figure will normally be larger that that actually observed, mainly because of receiver noise, but also because of inaccuracies in setting RF pulse angles, and relaxation effects. Phantom experiments were performed on the transmit-receive RF head coil of a commercial MRI system at 0.95 T using a projection method. The measured SNR agreed with that expected from the formula for achievable SNR once a correction was made for the noise figure of the receiving chain. Comparisons of measured SNR figures with those calculated from RF power measurements are expected to be of value in acceptance testing and quality control. (author)

A transmit/receive radiofrequency array for imaging the carotid arteries at 7 Tesla: coil design and first in vivo results.

Science.gov (United States)

Kraff, Oliver; Bitz, Andreas K; Breyer, Tobias; Kruszona, Stefan; Maderwald, Stefan; Brote, Irina; Gizewski, Elke R; Ladd, Mark E; Quick, Harald H

2011-04-01

To develop a transmit/receive radiofrequency (RF) array for magnetic resonance imaging (MRI) of the carotid arteries at 7 T. The prototype is characterized in numerical simulations and bench measurements, and the feasibility of plaque imaging at 7 T is demonstrated in first in vivo images. The RF phased array coil consists of 8 surface loop coils. To allow imaging of both sides of the neck, the RF array is divided into 2 coil clusters, each with 4 overlapping loop elements. For safety validation, numerical computations of the RF field distribution and the corresponding specific absorption rate were performed on the basis of a heterogeneous human body model. To validate the coil model, maps of the transmit B1(+) field were compared between simulation and measurement. In vivo images of a healthy volunteer and a patient (ulcerating plaque and a 50% stenosis of the right internal carotid artery) were acquired using a 3-dimensional FLASH sequence with a high isotropic spatial resolution of 0.54 mm as well as using pulse-triggered proton density (PD)/T2-weighted turbo spin echo sequences. Measurements of the S-parameters yielded a reflection and isolation of the coil elements of better than -18 and -13 dB, respectively. Measurements of the g-factor indicated good image quality for parallel imaging acceleration factors up to 2.4. A similar distribution and a very good match of the absolute values were found between the measured and simulated B1(+) transmit RF field for the validation of the coil model. In vivo images revealed good signal excitation of both sides of the neck and a high vessel-to-background image contrast for the noncontrast-enhanced 3-dimensional FLASH sequence. Imaging at 7 T could depict the extent of stenosis, and revealed the disruption and ulcer of the plaque. This study demonstrates that 2 four-channel transmit/receive RF arrays for each side of the neck is a suitable concept for in vivo MRI of the carotid arteries at 7 Tesla. Further studies are

Externally placed vs intravaginally positioned radio frequency coils for quantitative spin-spin relaxometry of ovarian follicular fluid

International Nuclear Information System (INIS)

Sarty, G.E.; Baerwald, A.R.; Loewy, J.; Pierson, R.A.

2005-01-01

To evaluate different imaging protocols, especially with respect to radio frequency (RF) receiver coil location, for Their suitability in providing least squares derived quantitative T 2 values of ovarian follicular fluid for investigations of basic ovarian physiology. Methods: The ovaries of 10 women were imaged via magnetic resonance imaging (MRI) using externally positioned and intravaginally placed RF receiver coils. Half-Fourier acquisition with single-shot turbo spin-echo (HASTE), multiple-echo T 2 , Dixon, turbo spin-echo, and 3-dimensional (3D) fast imaging with steady-state precession (FISP) and time-reversed FISP (PSIF) sequences were used. Quantitative T 2 nuclear spin relaxation rate information from the ovarian follicles between data acquired with the external and intravaginal coils were compared. Additionally, the amount of ovarian follicle and corpora lutea structural detail visible was qualitatively assessed. Results: The T 2 computations indicated that there was no difference in the follicular fluid T 2 values or in the heterogeneity (spatial variance) of the T 2 values between data acquired with the external RF coil and date acquired with the intravaginal RF coil. The best sequences for the visualization of ovarian internal structure were the 3D PSIF sequences and the multiple-echo T 2 -weighted images, confirming our earlier imaging work on excised cow ovaries. Conclusion: It is best to use an externally placed RF coil for quantitative MRI study of ovarian physiology given the lack of difference in quantitative T 2 information and the difficulty associated with imaging the ovaries using an intravaginal RF probe. (author)

Mid-range adiabatic wireless energy transfer via a mediator coil

International Nuclear Information System (INIS)

Rangelov, A.A.; Vitanov, N.V.

2012-01-01

A technique for efficient mid-range wireless energy transfer between two coils via a mediator coil is proposed. By varying the coil frequencies, three resonances are created: emitter–mediator (EM), mediator–receiver (MR) and emitter–receiver (ER). If the frequency sweeps are adiabatic and such that the EM resonance precedes the MR resonance, the energy flows sequentially along the chain emitter–mediator–receiver. If the MR resonance precedes the EM resonance, then the energy flows directly from the emitter to the receiver via the ER resonance; then the losses from the mediator are suppressed. This technique is robust against noise, resonant constraints and external interferences. - Highlights: ► Efficient and robust mid-range wireless energy transfer via a mediator coil. ► The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. ► Wireless energy transfer is insensitive to any resonant constraints. ► Wireless energy transfer is insensitive to noise in the neighborhood of the coils.

Borehole induction coil transmitter

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Vehicle to wireless power transfer coupling coil alignment sensor

Science.gov (United States)

Miller, John M.; Chambon, Paul H.; Jones, Perry T.; White, Clifford P.

2016-02-16

A non-contacting position sensing apparatus includes at least one vehicle-mounted receiver coil that is configured to detect a net flux null when the vehicle is optimally aligned relative to the primary coil in the charging device. Each of the at least one vehicle-mounted receiver coil includes a clockwise winding loop and a counterclockwise winding loop that are substantially symmetrically configured and serially connected to each other. When the non-contacting position sensing apparatus is located directly above the primary coil of the charging device, the electromotive forces from the clockwise winding loop and the counterclockwise region cancel out to provide a zero electromotive force, i.e., a zero voltage reading across the coil that includes the clockwise winding loop and the counterclockwise winding loop.

Measurement of heating coil temperature for e-cigarettes with a "top-coil" clearomizer.

Science.gov (United States)

Chen, Wenhao; Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A; Kumagai, Kazukiyo

2018-01-01

To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a "top-coil" clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3-6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such "top-coil" clearomizers. This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the

Unshielded asymmetric transmit-only and endorectal receive-only radiofrequency coil for (23) Na MRI of the prostate at 3 tesla.

Science.gov (United States)

Farag, Adam; Peterson, Justin Charles; Szekeres, Trevor; Bauman, Glenn; Chin, Joseph; Romagnoli, Cesare; Bartha, Robert; Scholl, Timothy J

2015-08-01

To develop and optimize radiofrequency (RF) hardware for the detection of endogenous sodium ((23) Na) by 3.0 Tesla (T) MRI in the human prostate. A transmit-only receive-only (TORO) RF system of resonators consisting of an unshielded, asymmetric, quadrature birdcage (transmit), and an endorectal (ER), linear, surface (receive) coil were developed and tested on a 3T MRI scanner. Two different ER receivers were constructed; a single-tuned ((23) Na) and a dual-tuned ((1) H/(23) Na). Both receivers were evaluated by the measurements of signal-to-noise ratio (SNR) and B1 homogeneity. For tissue sodium concentration (TSC) quantification, vials containing known sodium concentrations were incorporated into the ER. The system was used to measure the prostate TSC of three men (age 55 ± 5 years) with biopsy-proven prostate cancer. B1 field inhomogeneity of the asymmetric transmitter was estimated to be less than 5%. The mean SNR measured in a region of interest within the prostate using the single-tuned ER coil was 54.0 ± 4.6. The mean TSC in the central gland was 60.2 ± 5.7 mmol/L and in the peripheral gland was 70.5 ± 9.0 mmol/L. A TORO system was developed and optimized for (23) Na MRI of the human prostate which showed good sensitivity throughout the prostate for quantitative measurement of TSC. © 2014 Wiley Periodicals, Inc.

Design of a dynamic transcranial magnetic stimulation coil system.

Science.gov (United States)

Ge, Sheng; Jiang, Ruoli; Wang, Ruimin; Chen, Ji

2014-08-01

To study the brain activity at the whole-head range, transcranial magnetic stimulation (TMS) researchers need to investigate brain activity over the whole head at multiple locations. In the past, this has been accomplished with multiple single TMS coils that achieve quasi whole-head array stimulation. However, these designs have low resolution and are difficult to position and control over the skull. In this study, we propose a new dynamic whole-head TMS mesh coil system. This system was constructed using several sagittal and coronal directional wires. Using both simulation and real experimental data, we show that by varying the current direction and strength of each wire, this new coil system can form both circular coils or figure-eight coils that have the same features as traditional TMS coils. Further, our new system is superior to current coil systems because stimulation parameters such as size, type, location, and timing of stimulation can be dynamically controlled within a single experiment.

Three-axis orthogonal transceiver coil for eddy current sounding

Science.gov (United States)

Sukhanov, D.; Zavyalova, K.; Goncharik, M.

2017-08-01

We propose the new structure of three-axis transceiver magnetic-induction coil for eddy current probing. Due to the orientation of the coils, the direct signal from the transmitting coil to the receiving coil is minimized, which provided a high dynamic range. Sensitivity in all directions is provided by combining coils of different orientations. Numerical simulation and experimental studies of such a system have been carried out and confirmed the applicability of the proposed method and the mathematical model.

Invited review the coiled coil silk of bees, ants, and hornets.

Science.gov (United States)

Sutherland, Tara D; Weisman, Sarah; Walker, Andrew A; Mudie, Stephen T

2012-06-01

In this article, we review current knowledge about the silk produced by the larvae of bees, ants, and hornets [Apoidea and Vespoidea: Hymenoptera]. Different species use the silk either alone or in composites for a variety of purposes including mechanical reinforcement, thermal regulation, or humidification. The characteristic molecular structure of this silk is α-helical proteins assembled into tetrameric coiled coils. Gene sequences from seven species are available, and each species possesses a copy of each of four related silk genes that encode proteins predicted to form coiled coils. The proteins are ordered at multiple length scales within the labial gland of the final larval instar before spinning. The insects control the morphology of the silk during spinning to produce either fibers or sheets. The silk proteins are small and non repetitive and have been produced artificially at high levels by fermentation in E. coli. The artificial silk proteins can be fabricated into materials with structural and mechanical properties similar to those of native silks. Copyright © 2011 Wiley Periodicals, Inc.

Analysis and experimental study of wireless power transfer with HTS coil and copper coil as the intermediate resonators system

Science.gov (United States)

Wang, Xiufang; Nie, Xinyi; Liang, Yilang; Lu, Falong; Yan, Zhongming; Wang, Yu

2017-01-01

Intermediate resonator (repeater) between transmitter and receiver can significantly increase the distance of wireless power transfer (WPT) and the efficiency of wireless power transfer. The wireless power transfer via strongly coupled magnetic resonances with an high temperature superconducting (HTS) coil and copper coil as intermediate resonators was presented in this paper. The electromagnetic experiment system under different conditions with different repeating coils were simulated by finite element software. The spatial distribution patterns of magnetic induction intensity at different distances were plotted. In this paper, we examined transfer characteristics with HTS repeating coil and copper repeating coil at 77 K and 300 K, respectively. Simulation and experimental results show that HTS and copper repeating coil can effectively enhance the space magnetic induction intensity, which has significant effect on improving the transmission efficiency and lengthening transmission distance. We found that the efficiency and the distance of wireless power transfer system with an HTS coil as repeater is much higher by using of copper coil as repeater.

Analysis and experimental study of wireless power transfer with HTS coil and copper coil as the intermediate resonators system

International Nuclear Information System (INIS)

Wang, Xiufang; Nie, Xinyi; Liang, Yilang; Lu, Falong; Yan, Zhongming; Wang, Yu

2017-01-01

Highlights: • We investigated a kind of system architecture with three coils which the repeater is copper coil or HTS coil. • We simulated the different repeater system and obtained the magnetic field distribution at different distance. • We used helical coil instead of pancake coil which does not use capacitors. • HTS intermediate coil has significant effect on improving the transmission efficiency and lengthening transmission distance than copper intermediate coil. - Abstract: Intermediate resonator (repeater) between transmitter and receiver can significantly increase the distance of wireless power transfer (WPT) and the efficiency of wireless power transfer. The wireless power transfer via strongly coupled magnetic resonances with an high temperature superconducting (HTS) coil and copper coil as intermediate resonators was presented in this paper. The electromagnetic experiment system under different conditions with different repeating coils were simulated by finite element software. The spatial distribution patterns of magnetic induction intensity at different distances were plotted. In this paper, we examined transfer characteristics with HTS repeating coil and copper repeating coil at 77 K and 300 K, respectively. Simulation and experimental results show that HTS and copper repeating coil can effectively enhance the space magnetic induction intensity, which has significant effect on improving the transmission efficiency and lengthening transmission distance. We found that the efficiency and the distance of wireless power transfer system with an HTS coil as repeater is much higher by using of copper coil as repeater.

Analysis and experimental study of wireless power transfer with HTS coil and copper coil as the intermediate resonators system

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiufang [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Physics and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Nie, Xinyi [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Liang, Yilang [School of Physics and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Lu, Falong [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Yan, Zhongming, E-mail: wangxiufanghappy@163.com [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Wang, Yu [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

2017-01-15

Highlights: • We investigated a kind of system architecture with three coils which the repeater is copper coil or HTS coil. • We simulated the different repeater system and obtained the magnetic field distribution at different distance. • We used helical coil instead of pancake coil which does not use capacitors. • HTS intermediate coil has significant effect on improving the transmission efficiency and lengthening transmission distance than copper intermediate coil. - Abstract: Intermediate resonator (repeater) between transmitter and receiver can significantly increase the distance of wireless power transfer (WPT) and the efficiency of wireless power transfer. The wireless power transfer via strongly coupled magnetic resonances with an high temperature superconducting (HTS) coil and copper coil as intermediate resonators was presented in this paper. The electromagnetic experiment system under different conditions with different repeating coils were simulated by finite element software. The spatial distribution patterns of magnetic induction intensity at different distances were plotted. In this paper, we examined transfer characteristics with HTS repeating coil and copper repeating coil at 77 K and 300 K, respectively. Simulation and experimental results show that HTS and copper repeating coil can effectively enhance the space magnetic induction intensity, which has significant effect on improving the transmission efficiency and lengthening transmission distance. We found that the efficiency and the distance of wireless power transfer system with an HTS coil as repeater is much higher by using of copper coil as repeater.

T2-weighted prostate MRI at 7 Tesla using a simplified external transmit-receive coil array: correlation with radical prostatectomy findings in two prostate cancer patients.

Science.gov (United States)

Rosenkrantz, Andrew B; Zhang, Bei; Ben-Eliezer, Noam; Le Nobin, Julien; Melamed, Jonathan; Deng, Fang-Ming; Taneja, Samir S; Wiggins, Graham C

2015-01-01

To report design of a simplified external transmit-receive coil array for 7 Tesla (T) prostate MRI, including demonstration of the array for tumor localization using T2-weighted imaging (T2WI) at 7T before prostatectomy. Following simulations of transmitter designs not requiring parallel transmission or radiofrequency-shimming, a coil array was constructed using loop elements, with anterior and posterior rows comprising one transmit-receive element and three receive-only elements. This coil structure was optimized using a whole-body phantom. In vivo sequence optimization was performed to optimize achieved flip angle (FA) and signal to noise ratio (SNR) in prostate. The system was evaluated in a healthy volunteer at 3T and 7T. The 7T T2WI was performed in two prostate cancer patients before prostatectomy, and localization of dominant tumors was subjectively compared with histopathological findings. Image quality was compared between 3T and 7T in these patients. Simulations of the B1(+) field in prostate using two-loop design showed good magnitude (B1(+) of 0.245 A/m/w(1/2)) and uniformity (nonuniformity [SD/mean] of 10.4%). In the volunteer, 90° FA was achieved in prostate using 225 v 1 ms hard-pulse (indicating good efficiency), FA maps confirmed good uniformity (14.1% nonuniformity), and SNR maps showed SNR gain of 2.1 at 7T versus 3T. In patients, 7T T2WI showed excellent visual correspondence with prostatectomy findings. 7T images demonstrated higher estimated SNR (eSNR) in benign peripheral zone (PZ) and tumor compared with 3T, but lower eSNR in fat and slight decreases in tumor-to-PZ contrast and PZ-homogeneity. We have demonstrated feasibility of a simplified external coil array for high-resolution T2-weighted prostate MRI at 7T. © 2013 Wiley Periodicals, Inc.

Characteristic of wireless power transmission S-Parameter for a superconductor coil

International Nuclear Information System (INIS)

Jeong, In Sung; Jung, Byung Ik; Choi, Hyo Sang

2015-01-01

Many studies are being conducted to implement wireless charging, for example, for cellular phones or electronic tooth brushes, via wireless power transmission technique. However, the magnetic induction method had a very short transmission distance. To solve this problem, the team of Professor Marin Soljacic proposed a magnetic resonance system that used two resonance coils with the same resonance frequency. It had an approximately 40% efficiency at a 2m distance. The system improved the low efficiency and short distance problems of the existing systems. So it could also widen the application range of wireless power transmission. Many studies on the subject are underway. In this paper, the superconductor coil was used to improve the efficiency of magnetic resonance wireless power transmission. The resonance wireless power transmission system had a source coil, a load coil, and resonance coils (a transmitter and a receiver). The efficiency and distance depended on the characteristics of the transmitter and receiver coils that had the same resonance frequency. Therefore, two resonance coils were fabricated by superconductors. The current density of the superconductor was higher than that of the normal conductor coil. Accordingly, it had a high quality-factor and improved efficiency

Characteristic of wireless power transmission S-Parameter for a superconductor coil

Energy Technology Data Exchange (ETDEWEB)

Jeong, In Sung; Jung, Byung Ik; Choi, Hyo Sang [Chosun University, Gwangju (Korea, Republic of)

2015-03-15

Many studies are being conducted to implement wireless charging, for example, for cellular phones or electronic tooth brushes, via wireless power transmission technique. However, the magnetic induction method had a very short transmission distance. To solve this problem, the team of Professor Marin Soljacic proposed a magnetic resonance system that used two resonance coils with the same resonance frequency. It had an approximately 40% efficiency at a 2m distance. The system improved the low efficiency and short distance problems of the existing systems. So it could also widen the application range of wireless power transmission. Many studies on the subject are underway. In this paper, the superconductor coil was used to improve the efficiency of magnetic resonance wireless power transmission. The resonance wireless power transmission system had a source coil, a load coil, and resonance coils (a transmitter and a receiver). The efficiency and distance depended on the characteristics of the transmitter and receiver coils that had the same resonance frequency. Therefore, two resonance coils were fabricated by superconductors. The current density of the superconductor was higher than that of the normal conductor coil. Accordingly, it had a high quality-factor and improved efficiency.

[Development of RF coil of permanent magnet mini-magnetic resonance imager and mouse imaging experiments].

Science.gov (United States)

Hou, Shulian; Xie, Huantong; Chen, Wei; Wang, Guangxin; Zhao, Qiang; Li, Shiyu

2014-10-01

In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.

Assessment of the characteristics of MRI coils in terms of RF non-homogeneity using routine spin echo sequences

International Nuclear Information System (INIS)

Oghabian, M. A.; Mehdipour, Sh.; RiahicAlam, N.; Rafie, B.; Ghanaati, H.

2005-01-01

One of the major causes of image non-uniformity in MRI is due to the existence of non-homogeneity in RF receive and transmit. This can be the most effective source of error in quantitative studies in MRI imaging. Part of this non-homogeneity demonstrates the characteristics of RF coil and part of it is due to the interaction of RF field with the material being imaged. In this study, RF field non-homogeneity of surface and volume coils is measured using an oil phantom. The method employed in this work is based on a routine Spin Echo based sequence as proposed by this group previously. Materials and Methods: For the determination of RF non-uniformity, a method based on Spin Echo sequence (8θ-180) was used as reported previously by the same author. In this method, several images were obtained from one slice using different flip angles while keeping all other imaging parameters constant. Then, signal intensity at a ROI from all of these images were measured and fitted to the MRI defined mathematical model. Since this mathematical model describes the relation between signal intensity and flip angle in a (8θ-180) Spin Echo sequence, it is possible to obtain the variation in receive and transmit sensitivity in terms of the variation of signal intensity from the actual expected values. Since surface coils are functioning as only receiver (RF transmission is done by Body coil), first the results of receive coil homogeneity is measured, then characteristic of transmit coil (for the body coil) is evaluated Results: The coefficient of variation (C.V.) found for T(r) value obtained from images using head coils was in the order of 0.6%. Since the head coil is functioning as both transmitter and receiver, any non-uniformity in either transmit or receive stage can lead to non-homogeneity in RF field. A part from the surface coils, the amount of non-homogeneity due to receive coil was less than that of the transmit coil. In the case of the surface coils the variation in receive

Multiple-animal MR imaging using a 3T clinical scanner and multi-channel coil for volumetric analysis in a mouse tumor model

International Nuclear Information System (INIS)

Mitsuda, Minoru; Yamaguchi, Masayuki; Furuta, Toshihiro; Fujii, Hirofumi; Nabetani, Akira; Hirayama, Akira; Nozaki, Atsushi; Niitsu, Mamoru

2011-01-01

Multiple small-animal magnetic resonance (MR) imaging to measure tumor volume may increase the throughput of preclinical cancer research assessing tumor response to novel therapies. We used a clinical scanner and multi-channel coil to evaluate the usefulness of this imaging to assess experimental tumor volume in mice. We performed a phantom study to assess 2-dimensional (2D) geometric distortion using 9-cm spherical and 32-cell (8 x 4 one-cm 2 grids) phantoms using a 3-tesla clinical MR scanner and dedicated multi-channel coil composed of 16 5-cm circular coils. Employing the multi-channel coil, we simultaneously scanned 6 or 8 mice bearing sarcoma 180 tumors. We estimated tumor volume from the sum of the product of tumor area and slice thickness on 2D spin-echo images (repetition time/echo time, 3500/16 ms; in-plane resolution, 0.195 x 0.195 x 1 mm 3 ). After MR acquisition, we excised and weighed tumors, calculated reference tumor volumes from actual tumor weight assuming a density of 1.05 g/cm 3 , and assessed the correlation between the estimated and reference volumes using Pearson's test. Two-dimensional geometric distortion was acceptable below 5% in the 9-cm spherical phantom and in every cell in the 32-cell phantom. We scanned up to 8 mice simultaneously using the multi-channel coil and found 11 tumors larger than 0.1 g in 12 mice. Tumor volumes were 1.04±0.73 estimated by MR imaging and 1.04±0.80 cm 3 by reference volume (average±standard deviation) and highly correlated (correlation coefficient, 0.995; P<0.01, Pearson's test). Use of multiple small-animal MR imaging employing a clinical scanner and multi-channel coil enabled accurate assessment of experimental tumor volume in a large number of mice and may facilitate high throughput monitoring of tumor response to therapy in preclinical research. (author)

A periodic table of coiled-coil protein structures.

Science.gov (United States)

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.

Measuring Balance Across Multiple Radar Receiver Channels.

Energy Technology Data Exchange (ETDEWEB)

Doerry, Armin W.; Bickel, Douglas L.

2018-03-01

When radar receivers employ multiple channels, the general intent is for the receive channels to be as alike as possible, if not as ideal as possible. This is usually done via prudent hardware design, supplemented by system calibration. Towards this end, we require a quality metric for ascertaining the goodness of a radar channel, and the degree of match to sibling channels. We propose a relevant and useable metric to do just that. Acknowledgements This report was the result of an unfunded research and development activity.

[Surface coils for magnetic-resonance images].

Science.gov (United States)

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.

Large coil task and results of testing US coils

International Nuclear Information System (INIS)

Haubenreich, P.N.

1986-01-01

The United States, EURATOM, Japan, and Switzerland have collaborated since 1978 in development of superconducting toroidal field coils for fusion reactor applications. The United States provided a test facility nd three coils; the other participants, one coil each. All coils have the same interface dimensions and performance requirements (stable at 8 T), but internal design was decided by each team. Two US coil teams chose bath-cooled NbTi, 10-kA conductors. One developed a Nb 3 Sn conductor, cooled by internal flow, rated at 18 kA. All US coils have diagnostic instrumentation and imbedded heaters that enable stability tests and simulated nuclear heating experiments. In single-coil tests, each coil operated at full current in self-field (6.4 T). In six-coil tests that began in July 1986, one US coil and the Japanese coil hve been successfully operated at full current at 8 T. The other coils have operated as background coils while awaiting their turn as test coil. Coil tests have been informative and results gratifying. The facility has capably supported coil testing and its operation has provided information that will be useful in designing future fusion systems. Coil capabilities beyond nominal design points will be determined

Tesla Coil Theoretical Model and its Experimental Verification

OpenAIRE

Voitkans Janis; Voitkans Arnis

2014-01-01

In this paper a theoretical model of Tesla coil operation is proposed. Tesla coil is described as a long line with distributed parameters in a single-wire form, where the line voltage is measured across electrically neutral space. By applying the principle of equivalence of single-wire and two-wire schemes an equivalent two-wire scheme can be found for a single-wire scheme and the already known long line theory can be applied to the Tesla coil. A new method of multiple re...

Transmit coil design for Wireless Power Transfer for medical implants.

Science.gov (United States)

Lemdiasov, Rosti; Venkatasubramanian, Arun

2017-07-01

A new design approach for the design of transmit coils for Wireless Power Transfer (WPT) is presented. The theoretical formulation involves a figure of merit that has to be maximized to solve for the surface current. Numerical predictions and comparisons with practical measurements for the coil parameters (inductance. resistance) underscore the success of this approach in terms of achieving strong coupling with a receive coil while maintaining low resistance.

Optimization of multiple coils immersed in a conducting liquid for half-hemisphere or whole-brain deep transcranial magnetic stimulation: a simulation study.

Science.gov (United States)

Sousa, Sónia C P; Almeida, Jorge; Cavaleiro Miranda, Pedro; Salvador, Ricardo; Silvestre, João; Simões, Hugo; Crespo, Paulo

2014-01-01

Transcranial magnetic stimulation (TMS) was proposed in 1985. Nevertheless, its wider use in the treatment of several neurologic diseases has been hindered by its inability to stimulate deep-brain regions. This is mainly due to the physical limiting effect arising from the presence of surface discontinuities, particularly between the scalp and air. Here, we present the optimization of a system of large multiple coils for whole-brain and half-hemisphere deep TMS, termed orthogonal configuration. COMSOL(®)-based simulations show that the system is capable of reaching the very center of a spherical brain phantom with 58% induction relative to surface maximum. Such penetration capability surpasses to the best of our knowledge that of existing state of the art TMS systems. This induction capability strongly relies on the immersion of the stimulating coils and part of the head of the patient in a conducting liquid (e.g. simple saline solution). We show the impact of the presence of this surrounding conducting liquid by comparing the performance of our system with and without such liquid. In addition, we also compare the performance of the proposed coil with that of a circular coil, a figure-eight coil, and the H-coil. Finally, in addition to its whole-brain stimulation capability (e.g. potentially useful for prophylaxis of epileptic patients) the system is also able to stimulate mainly one brain hemisphere, which may be useful in stroke rehabilitation, among other applications.

Giant High-Flow Type Pulmonary Arteriovenous Malformation: Coil Embolization with Flow Control by Balloon Occlusion and an Anchored Detachable Coil

International Nuclear Information System (INIS)

Kanematsu, Masayuki; Kondo, Hiroshi; Goshima, Satoshi; Tsuge, Yusuke; Watanabe, Haruo; Moriyama, Noriyuki

2012-01-01

Pulmonary arteriovenous malformations (PAVMs) are often treated by pushable fibered or non-fibered microcoils, using an anchor or scaffold technique or with an Amplatzer plug through a guiding sheath. When performing percutaneous transcatheter microcoil embolization, there is a risk of coil migration, particularly with high-flow type PAVMs. The authors report on a unique treatment in a patient with a giant high-flow PAVM whose nidus had a maximum diameter of 6 cm. A detachable coil, not detached from a delivery wire (an anchored detachable coil), was first placed in the feeding artery under flow control by balloon occlusion, and then multiple microcoils were packed proximally to the anchored detachable coil. After confirming the stability of the microcoils during a gradual deflation of the balloon, we finally released the first detachable coil. The nidus was reduced in size to 15 mm at one year postoperatively.

Characterization and evaluation of a flexible MRI receive coil array for radiation therapy MR treatment planning using highly decoupled RF circuits

Science.gov (United States)

McGee, Kiaran P.; Stormont, Robert S.; Lindsay, Scott A.; Taracila, Victor; Savitskij, Dennis; Robb, Fraser; Witte, Robert J.; Kaufmann, Timothy J.; Huston, John, III; Riederer, Stephen J.; Borisch, Eric A.; Rossman, Phillip J.

2018-04-01

The growth in the use of magnetic resonance imaging (MRI) data for radiation therapy (RT) treatment planning has been facilitated by scanner hardware and software advances that have enabled RT patients to be imaged in treatment position while providing morphologic and functional assessment of tumor volumes and surrounding normal tissues. Despite these advances, manufacturers have been slow to develop radiofrequency (RF) coils that closely follow the contour of a RT patient undergoing MR imaging. Instead, relatively large form surface coil arrays have been adapted from diagnostic imaging. These arrays can be challenging to place on, and in general do not conform to the patient’s body habitus, resulting in sub optimal image quality. The purpose of this study is to report on the characterization of a new flexible and highly decoupled RF coil for use in MR imaging of RT patients. Coil performance was evaluated by performing signal-to-noise ratio (SNR) and noise correlation measurements using two coil (SNR) and four coil (noise correlation) element combinations as a function of coil overlap distance and comparing these values to those obtained using conventional coil elements. In vivo testing was performed in both normal volunteers and patients using a four and 16 element RF coil. Phantom experiments demonstrate the highly decoupled nature of the new coil elements when compared to conventional RF coils, while in vivo testing demonstrate that these coils can be integrated into extremely flexible and form fitting substrates that follow the exact contour of the patient. The new coil design addresses limitations imposed by traditional surface coil arrays and have the potential to significantly impact MR imaging for both diagnostic and RT applications.

High performance 3-coil wireless power transfer system for the 512-electrode epiretinal prosthesis.

Science.gov (United States)

Zhao, Yu; Nandra, Mandheerej; Yu, Chia-Chen; Tai, Yu-chong

2012-01-01

The next-generation retinal prostheses feature high image resolution and chronic implantation. These features demand the delivery of power as high as 100 mW to be wireless and efficient. A common solution is the 2-coil inductive power link, used by current retinal prostheses. This power link tends to include a larger-size extraocular receiver coil coupled to the external transmitter coil, and the receiver coil is connected to the intraocular electrodes through a trans-sclera trans-choroid cable. In the long-term implantation of the device, the cable may cause hypotony (low intraocular pressure) and infection. However, when a 2-coil system is constructed from a small-size intraocular receiver coil, the efficiency drops drastically which may induce over heat dissipation and electromagnetic field exposure. Our previous 2-coil system achieved only 7% power transfer. This paper presents a fully intraocular and highly efficient wireless power transfer system, by introducing another inductive coupling link to bypass the trans-sclera trans-choroid cable. With the specific equivalent load of our customized 512-electrode stimulator, the current 3-coil inductive link was measured to have the overall power transfer efficiency around 36%, with 1-inch separation in saline. The high efficiency will favorably reduce the heat dissipation and electromagnetic field exposure to surrounding human tissues. The effect of the eyeball rotation on the power transfer efficiency was investigated as well. The efficiency can still maintain 14.7% with left and right deflection of 30 degree during normal use. The surgical procedure for the coils' implantation into the porcine eye was also demonstrated.

Bifurcation and stability of forced convection in tightly coiled ducts: multiplicity

International Nuclear Information System (INIS)

Wang Liqiu; Pang, Ophelia; Cheng Lin

2005-01-01

A numerical study is made on the fully developed bifurcation structure of the forced convection in tightly coiled ducts of square cross-section. In addition to the examination of structural changes of three known solution branches found in loosely coiled ducts, three new solution branches are found. These new branches are isolated from the three known branches. The flows on these new branches are in a symmetric 4-cell state, a symmetric 8-cell state, an asymmetric 2-cell state, an asymmetric 5-cell state, an asymmetric 7-cell state, or an asymmetric 8-cell structure

Extending the self-assembly of coiled-coil hybrids

NARCIS (Netherlands)

Robson Marsden, Hana

2009-01-01

Of the various biomolecular building blocks in use in nature, coiled-coil forming peptides are amongst those with the most potential as building blocks for the synthetic self-assembly of nanostructures. Native coiled coils have the ability to function in, and influence, complex systems composed of

A 32-channel lattice transmission line array for parallel transmit and receive MRI at 7 tesla.

Science.gov (United States)

Adriany, Gregor; Auerbach, Edward J; Snyder, Carl J; Gözübüyük, Ark; Moeller, Steen; Ritter, Johannes; Van de Moortele, Pierre-François; Vaughan, Tommy; Uğurbil, Kâmil

2010-06-01

Transmit and receive RF coil arrays have proven to be particularly beneficial for ultra-high-field MR. Transmit coil arrays enable such techniques as B(1) (+) shimming to substantially improve transmit B(1) homogeneity compared to conventional volume coil designs, and receive coil arrays offer enhanced parallel imaging performance and SNR. Concentric coil arrangements hold promise for developing transceiver arrays incorporating large numbers of coil elements. At magnetic field strengths of 7 tesla and higher where the Larmor frequencies of interest can exceed 300 MHz, the coil array design must also overcome the problem of the coil conductor length approaching the RF wavelength. In this study, a novel concentric arrangement of resonance elements built from capacitively-shortened half-wavelength transmission lines is presented. This approach was utilized to construct an array with whole-brain coverage using 16 transceiver elements and 16 receive-only elements, resulting in a coil with a total of 16 transmit and 32 receive channels. (c) 2010 Wiley-Liss, Inc.

Tesla Coil Theoretical Model and its Experimental Verification

Directory of Open Access Journals (Sweden)

Voitkans Janis

2014-12-01

Full Text Available In this paper a theoretical model of Tesla coil operation is proposed. Tesla coil is described as a long line with distributed parameters in a single-wire form, where the line voltage is measured across electrically neutral space. By applying the principle of equivalence of single-wire and two-wire schemes an equivalent two-wire scheme can be found for a single-wire scheme and the already known long line theory can be applied to the Tesla coil. A new method of multiple reflections is developed to characterize a signal in a long line. Formulas for calculation of voltage in Tesla coil by coordinate and calculation of resonance frequencies are proposed. The theoretical calculations are verified experimentally. Resonance frequencies of Tesla coil are measured and voltage standing wave characteristics are obtained for different output capacities in the single-wire mode. Wave resistance and phase coefficient of Tesla coil is obtained. Experimental measurements show good compliance with the proposed theory. The formulas obtained in this paper are also usable for a regular two-wire long line with distributed parameters.

A 16-channel MR coil for simultaneous PET/MR imaging in breast cancer

International Nuclear Information System (INIS)

Dregely, Isabel; Lanz, Titus; Mueller, Matthias F.; Metz, Stephan; Kuschan, Marika; Nimbalkar, Manoj; Ziegler, Sibylle I.; Nekolla, Stephan G.; Schwaiger, Markus; Bundschuh, Ralph A.; Haase, Axel

2015-01-01

To implement and evaluate a dedicated receiver array coil for simultaneous positron emission tomography/magnetic resonance (PET/MR) imaging in breast cancer. A 16-channel receiver coil design was optimized for simultaneous PET/MR imaging. To assess MR performance, the signal-to-noise ratio, parallel imaging capability and image quality was evaluated in phantoms, volunteers and patients and compared to clinical standard protocols. For PET evaluation, quantitative 18 F-FDG PET images of phantoms and seven patients (14 lesions) were compared to images without the coil. In PET image reconstruction, a CT-based template of the coil was combined with the MR-acquired attenuation correction (AC) map of the phantom/patient. MR image quality was comparable to clinical MR-only examinations. PET evaluation in phantoms showed regionally varying underestimation of the standardised uptake value (SUV; mean 22 %) due to attenuation caused by the coil. This was improved by implementing the CT-based coil template in the AC (<2 % SUV underestimation). Patient data indicated that including the coil in the AC increased the SUV values in the lesions (21 ± 9 %). Using a dedicated PET/MR breast coil, state-of-the-art MRI was possible. In PET, accurate quantification and image homogeneity could be achieved if a CT-template of this coil was included in the AC for PET image reconstruction. (orig.)

Zero Quantum Nuclear Magnetic Resonance experiments utilizing a toroid cell and coil

OpenAIRE

Bebout, William Roach

1989-01-01

Over the past ten to fifteen years the area of Nuclear Magnetic Resonance (NMR) Spectroscopy has seen tremendous growth. For example, in conjunction with multiple quantum NMR, molecular structural mapping of a compound can be easily performed in a two dimensional (2D) experiment. However, only two kinds of detector coils have been typically used in NMR studies. These are the solenoid coil and the Helmholtz coil. The solenoid coil was very popular with the permanent and e...

Dynamic multi-channel TMS with reconfigurable coil.

Science.gov (United States)

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.

High-field superconducting nested coil magnet

Science.gov (United States)

Laverick, C.; Lobell, G. M.

1970-01-01

Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

Modular coils: a promising toroidal-reactor-coil system

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

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.

Design of an interventional magnetic resonance imaging coil for cerebral surgery

Science.gov (United States)

Xu, Yue; Wang, Wen-Tao; Wang, Wei-Min

2012-11-01

In clinical magnetic resonance imaging (MRI), the design of the radiofrequency (RF) coil is very important. For certain applications, the appropriate coil can produce an improved image quality. However, it is difficult to achieve a uniform B1 field and a high signal-to-noise ratio (SNR) simultaneously. In this article, we design an interventional transmitter-and-receiver RF coil for cerebral surgery. This coil adopts a disassembly structure that can be assembled and disassembled repeatedly on the cerebral surgery gantry to reduce the amount of interference from the MRI during surgery. The simulation results and the imaging experiments demonstrate that this coil can produce a uniform RF field, a high SNR, and a large imaging range to meet the requirements of the cerebral surgery.

Efficacy of deep rTMS for neuropathic pain in the lower limb: a randomized, double-blind crossover trial of an H-coil and figure-8 coil.

Science.gov (United States)

Shimizu, Takeshi; Hosomi, Koichi; Maruo, Tomoyuki; Goto, Yuko; Yokoe, Masaru; Kageyama, Yu; Shimokawa, Toshio; Yoshimine, Toshiki; Saitoh, Youichi

2017-11-01

OBJECTIVE Electrical motor cortex stimulation can relieve neuropathic pain (NP), but its use requires patients to undergo an invasive procedure. Repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex (M1) using a figure-8 coil can relieve NP noninvasively, but its ability to relieve lower limb pain is still limited. Deep rTMS using an H-coil can effectively stimulate deep brain regions and has been widely used for the treatment of various neurological diseases; however, there have been no clinical studies comparing the effectiveness of figure-8 coils and H-coils. This study assessed the clinical effectiveness of 5 once-daily stimulations with H-coils and figure-8 coils in patients with NP. METHODS This randomized, double-blind, 3-way crossover trial examined 18 patients with NP who sequentially received 3 types of stimulations in the M1 for 5 consecutive days; each 5-day stimulation period was followed by a 17-day follow-up period before crossing over to the next type of stimulation. During each rTMS session, patients received a 5-Hz rTMS to the M1 region corresponding to the painful lower limb. The visual analog scale (VAS) and the Japanese version of the short-form McGill Pain Questionnaire 2 (SF-MPQ2-J) were used to measure pain intensity. The primary outcome was VAS score reduction immediately after and 1 hour after intervention. RESULTS Both the VAS and SF-MPQ2-J showed significant pain improvement immediately after deep rTMS with an H-coil as compared with the sham group (p H-coil (p = 0.004) but not 1 hour after rTMS using a figure-8 coil. None of the patients exhibited any serious adverse events. CONCLUSIONS The current findings suggest that the use of deep rTMS with an H-coil in the lower limb region of the M1 in patients with NP was tolerable and could provide significant short-term pain relief. Clinical trial registration no.: UMIN000010536 ( http://www.umin.ac.jp/ctr/ ).

Analysis and Optimization of Four-Coil Planar Magnetically Coupled Printed Spiral Resonators

Directory of Open Access Journals (Sweden)

Sadeque Reza Khan

2016-08-01

Full Text Available High-efficiency power transfer at a long distance can be efficiently established using resonance-based wireless techniques. In contrast to the conventional two-coil-based inductive links, this paper presents a magnetically coupled fully planar four-coil printed spiral resonator-based wireless power-transfer system that compensates the adverse effect of low coupling and improves efficiency by using high quality-factor coils. A conformal architecture is adopted to reduce the transmitter and receiver sizes. Both square architecture and circular architectures are analyzed and optimized to provide maximum efficiency at a certain operating distance. Furthermore, their performance is compared on the basis of the power-transfer efficiency and power delivered to the load. Square resonators can produce higher measured power-transfer efficiency (79.8% than circular resonators (78.43% when the distance between the transmitter and receiver coils is 10 mm of air medium at a resonant frequency of 13.56 MHz. On the other hand, circular coils can deliver higher power (443.5 mW to the load than the square coils (396 mW under the same medium properties. The performance of the proposed structures is investigated by simulation using a three-layer human-tissue medium and by experimentation.

Analysis and Optimization of Four-Coil Planar Magnetically Coupled Printed Spiral Resonators.

Science.gov (United States)

Khan, Sadeque Reza; Choi, GoangSeog

2016-08-03

High-efficiency power transfer at a long distance can be efficiently established using resonance-based wireless techniques. In contrast to the conventional two-coil-based inductive links, this paper presents a magnetically coupled fully planar four-coil printed spiral resonator-based wireless power-transfer system that compensates the adverse effect of low coupling and improves efficiency by using high quality-factor coils. A conformal architecture is adopted to reduce the transmitter and receiver sizes. Both square architecture and circular architectures are analyzed and optimized to provide maximum efficiency at a certain operating distance. Furthermore, their performance is compared on the basis of the power-transfer efficiency and power delivered to the load. Square resonators can produce higher measured power-transfer efficiency (79.8%) than circular resonators (78.43%) when the distance between the transmitter and receiver coils is 10 mm of air medium at a resonant frequency of 13.56 MHz. On the other hand, circular coils can deliver higher power (443.5 mW) to the load than the square coils (396 mW) under the same medium properties. The performance of the proposed structures is investigated by simulation using a three-layer human-tissue medium and by experimentation.

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

International Nuclear Information System (INIS)

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

2008-01-01

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

T1 weighted brain images at 7 Tesla unbiased for Proton Density, T2* contrast and RF coil receive B1 sensitivity with simultaneous vessel visualization.

Science.gov (United States)

Van de Moortele, Pierre-François; Auerbach, Edwards J; Olman, Cheryl; Yacoub, Essa; Uğurbil, Kâmil; Moeller, Steen

2009-06-01

At high magnetic field, MR images exhibit large, undesirable signal intensity variations commonly referred to as "intensity field bias". Such inhomogeneities mostly originate from heterogeneous RF coil B(1) profiles and, with no appropriate correction, are further pronounced when utilizing rooted sum of square reconstruction with receive coil arrays. These artifacts can significantly alter whole brain high resolution T(1)-weighted (T(1)w) images that are extensively utilized for clinical diagnosis, for gray/white matter segmentation as well as for coregistration with functional time series. In T(1) weighted 3D-MPRAGE sequences, it is possible to preserve a bulk amount of T(1) contrast through space by using adiabatic inversion RF pulses that are insensitive to transmit B(1) variations above a minimum threshold. However, large intensity variations persist in the images, which are significantly more difficult to address at very high field where RF coil B(1) profiles become more heterogeneous. Another characteristic of T(1)w MPRAGE sequences is their intrinsic sensitivity to Proton Density and T(2)(*) contrast, which cannot be removed with post-processing algorithms utilized to correct for receive coil sensitivity. In this paper, we demonstrate a simple technique capable of producing normalized, high resolution T(1)w 3D-MPRAGE images that are devoid of receive coil sensitivity, Proton Density and T(2)(*) contrast. These images, which are suitable for routinely obtaining whole brain tissue segmentation at 7 T, provide higher T(1) contrast specificity than standard MPRAGE acquisitions. Our results show that removing the Proton Density component can help in identifying small brain structures and that T(2)(*) induced artifacts can be removed from the images. The resulting unbiased T(1)w images can also be used to generate Maximum Intensity Projection angiograms, without additional data acquisition, that are inherently registered with T(1)w structural images. In addition

T1 weighted Brain Images at 7 Tesla Unbiased for Proton Density, T2* contrast and RF Coil Receive B1 Sensitivity with Simultaneous Vessel Visualization

Science.gov (United States)

Van de Moortele, Pierre-François; Auerbach, Edwards J.; Olman, Cheryl; Yacoub, Essa; Uğurbil, Kâmil; Moeller, Steen

2009-01-01

At high magnetic field, MR images exhibit large, undesirable signal intensity variations commonly referred to as “intensity field bias”. Such inhomogeneities mostly originate from heterogeneous RF coil B1 profiles and, with no appropriate correction, are further pronounced when utilizing rooted sum of square reconstruction with receive coil arrays. These artifacts can significantly alter whole brain high resolution T1-weighted (T1w) images that are extensively utilized for clinical diagnosis, for gray/white matter segmentation as well as for coregistration with functional time series. In T1 weighted 3D-MPRAGE sequences, it is possible to preserve a bulk amount of T1 contrast through space by using adiabatic inversion RF pulses that are insensitive to transmit B1 variations above a minimum threshold. However, large intensity variations persist in the images, which are significantly more difficult to address at very high field where RF coil B1 profiles become more heterogeneous. Another characteristic of T1w MPRAGE sequences is their intrinsic sensitivity to Proton Density and T2* contrast, which cannot be removed with post-processing algorithms utilized to correct for receive coil sensitivity. In this paper, we demonstrate a simple technique capable of producing normalized, high resolution T1w 3D-MPRAGE images that are devoid of receive coil sensitivity, Proton Density and T2* contrast. These images, which are suitable for routinely obtaining whole brain tissue segmentation at 7 Tesla, provide higher T1 contrast specificity than standard MPRAGE acquisitions. Our results show that removing the Proton Density component can help identifying small brain structures and that T2* induced artifacts can be removed from the images. The resulting unbiased T1w images can also be used to generate Maximum Intensity Projection angiograms, without additional data acquisition, that are inherently registered with T1w structural images. In addition, we introduce a simple technique

Sensitive quench detection of the HTS coil using a co-winding coil

International Nuclear Information System (INIS)

Takagi, Tomohiro; Ariyama, Takahiro; Takao, Tomoaki; Tsukamoto, Osami

2017-01-01

The authors have studied the co-winding coil method (CW method) using the co-wound coil electrically insulated from the HTS coil. In this method, the quench is detected by the voltage difference between the coil of the HTS tape (HTS coil) and the coil of the normal conductor (CW coil). The voltage induced in the CW coil caused by the change of the magnetic field is almost the same as that in the HTS coil because the coils are magnetically coupled close to each other. Therefore, it is expected that the induced voltage will be canceled with high accuracy and that the resistive voltage in the HTS coil will be detected with greater sensitivity compared to the bridge balance method, which is used commonly. In this study, quench detection applying the CW method is demonstrated using an experimental double-pancake coil. A tape with the copper layer deposited on the polymer substrate was used as the insulated conductor wire to form the CW coil. An additional pancake coil was used to expose the experimental double-pancake coil to the external magnetic field asymmetrically. It was shown that the CW method can detect the resistive voltage with greater sensitivity even when the HTS coil was exposed to the changing asymmetric external magnetic field. (author)

Device for supporting a toroidal coil in a toroidal type nuclear fusion device

International Nuclear Information System (INIS)

Kitazawa, Hakaru; Sato, Hiroshi.

1975-01-01

Object: To easily manufacture a center block having a strength sufficient to withstand an electromagnetic force exerted on the center of toroidal of a toroidal coil and to increase its reliability. Structure: In a device for supporting toroidal coils wherein the electromagnetic force exerted on the center of toroidal of a plurality of toroidal coils arranged in toroidal fashion, the contact surface between the toroidal coil and the center block is arranged parallel to the center axis of toroidal so as to receive the electromagnetic force exerted on the center of toroidal of the toroidal coil as the component of force in a radial direction. (Taniai, N.)

Optimization of Coil Element Configurations for a Matrix Gradient Coil.

Science.gov (United States)

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

2018-01-01

Recently, matrix gradient coils (also termed multi-coils or multi-coil arrays) were introduced for imaging and B 0 shimming with 24, 48, and even 84 coil elements. However, in imaging applications, providing one amplifier per coil element is not always feasible due to high cost and technical complexity. In this simulation study, we show that an 84-channel matrix gradient coil (head insert for brain imaging) is able to create a wide variety of field shapes even if the number of amplifiers is reduced. An optimization algorithm was implemented that obtains groups of coil elements, such that a desired target field can be created by driving each group with an amplifier. This limits the number of amplifiers to the number of coil element groups. Simulated annealing is used due to the NP-hard combinatorial nature of the given problem. A spherical harmonic basis set up to the full third order within a sphere of 20-cm diameter in the center of the coil was investigated as target fields. We show that the median normalized least squares error for all target fields is below approximately 5% for 12 or more amplifiers. At the same time, the dissipated power stays within reasonable limits. With a relatively small set of amplifiers, switches can be used to sequentially generate spherical harmonics up to third order. The costs associated with a matrix gradient coil can be lowered, which increases the practical utility of matrix gradient coils.

Interaction between shock coils increased the incidence of inappropriate therapies and lead failure in implantable cardioverter defibrillator.

Science.gov (United States)

El Garhy, Mohammad; Ohlow, Marc-Alexander; Lauer, Bernward

Shock coil interaction in patients with multiple implantable cardioverter defibrillator (ICD) leads is occasionally observed. We aimed to evaluate the incidence of shock coil interaction and its clinical relevance. All ICD patients (646 patients) who came to follow up control in our ICD ambulance between January 1, 2011, and December 31, 2011 in the department of cardiology in Bad Berka hospital were retrospectively evaluated in this study. All baseline demographic, clinical, and procedural characteristics and postoperative chest x ray in postero-anterior and lateral view as well as clinical and ICD follow up data were evaluated. Among 646 patients 42 had multiple ICD leads (6.5%) of whom 36 patients (5.5% of total cohort patients and 85.7% of patients with multiple ICD leads) had shock coil interaction and presented the study group (Group I). The control group (Group II) consisted of 610 patients without coil-coil interaction including patients with single shock lead (604 patients) or patients with multiple leads but without interaction between shock coils (6 patients). Inappropriate anti-tachycardia therapies and RV lead revisions were more frequent in patients with interaction between shock coils (Group I vs Group II: 27.7% and 5.7%; p = 0.049 and 30.6% vs 6.4; p = 0.0001, respectively). Interaction between shock coils may be one of possible causes of lead failure and resulted in inappropriate therapies and subsequent lead revision. Copyright © 2018 Indian Heart Rhythm Society. Production and hosting by Elsevier B.V. All rights reserved.

16-Channel surface coil for 13C-hyperpolarized spectroscopic imaging of cardiac metabolism in pig heart

DEFF Research Database (Denmark)

Frijia, Francesca; Santarelli, Maria Filomena; Koellisch, Ulrich

2016-01-01

Magnetic resonance spectroscopy (MRS) of hyperpolarized 13C pyruvate and its metabolites in large animal models is a powerful tool for assessing cardiac metabolism in patho-physiological conditions. In 13C studies, a high signal-to-noise ratio (SNR) is crucial to overcome the intrinsic data quality...... both targets. In this study, a 16-channel receive surface coil was designed for 13C hyperpolarized studies of the pig heart with a clinical 3-T scanner. The coil performance was characterized by phantom experiments and compared with that of a birdcage coil used in transmit/receive mode. Segmental...... of the 16-channel coil is recommended for studies of septal and anterior LV walls....

Isabelle dipole and quadrupole coil configurations

International Nuclear Information System (INIS)

Dahl, P.F.; Hahn, H.

1980-01-01

The coil configurations of the ISABELLE dipole and quadrupole magnets have been reviewed and a number of improvements were suggested for incorporation into the final design. The coil designs are basically single layer multiple block approximations to cosine current distributions, wound from a high aspect ratio non-keystoned braided conductor. The blocks are separated by knife-edge wedges to maximize the quench propagation velocity. The current density variation is obtained by an appropriate distribution of the spacer turns and, to a lesser degree, by the wedge locations. The use of inert turns is necessary to minimize the peak field enhancement both in the ends and in the two dimensional section. Schemes for deriving turns distributions yielding harmonic coefficients satisfying the stringent ISABELLE tolerances on field uniformity, while allowing for simplicity in winding and taking into account quench propagation considerations, will be discussed, as well as our approach to the coil end configuration

Progress of the ITER Correction Coils in China

CERN Document Server

Wei, J; Han, S; Yu, X; Du, S; Li, C; Fang, C; Wang, L; Zheng, W; Liu, L; Wen, J; Li, H; Libeyre, P; Dolgetta, N; Cormany, C; Sgobba, S

2014-01-01

The ITER Correction Coils (CC) include three sets of six coils each, distributed symmetrically around the tokamak to correct error fields. Each pair of coils, located on opposite sides of the tokamak, is series connected with polarity to produce asymmetric fields. The manufacturing of these superconducting coils is undergoing qualification of the main fabrication processes: winding into multiple pancakes, welding helium inlet/outlet on the conductor jacket, turn and ground insulation, vacuum pressure impregnation, inserting into an austenitic stainless steel case, enclosure welding, and assembling the terminal service box. It has been proceeding by an intense phase of R\\&D, trials tests, and final adjustment of the tooling. This paper mainly describes the progress in ASIPP for the CC manufacturing process before and on qualification phase and the status of corresponding equipment which are ordered or designed for each process. Some test results for the key component and procedure are also presented.

Routine phasing of coiled-coil protein crystal structures with AMPLE

Directory of Open Access Journals (Sweden)

Jens M. H. Thomas

2015-03-01

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

An innovative design for using flexible printed coils for magnetostrictive-based longitudinal guided wave sensors in steel strand inspection

International Nuclear Information System (INIS)

Tse, P W; Liu, X C; Wang, X J; Liu, Z H; Wu, B; He, C F

2011-01-01

Magnetostrictive sensors (MsSs) that can excite and receive guided waves are commonly used in detecting defects that may occur in cables and strands for supporting heavy structures. A conventional MsS has a hard sensing coil that is wound onto a bobbin with electric wires to generate the necessary dynamic magnetic field to excite the desired guided waves. This tailor-made hard coil is usually bulky and is not flexible enough to fit steel strands of various sizes. The conventional MsS also cannot be mounted to any steel strand that does not have a free end to allow the bobbin to pass through the structure of the tested strand. Such inflexibilities limit the use of conventional MsSs in practical situations. To solve these limitations, an innovative type of coil, called a flexible printed coil (FPC), which is made out of flexible printed film, has been designed to replace the inflexible hard coil. The flexible structure of the FPC ensures that the new MsS can be easily installed on and removed from steel strands with different diameters and without free ends. Moreover, the FPC-based MsS can be wrapped into multiple layers due to its thin and flexible design. Although multi-layer FPC creates a minor asymmetry in the dynamic magnetic field, the results of finite element analysis and experiments confirm that the longitudinal guided waves excited by a FPC-based MsS are comparable to those excited by a conventional hard coil MsS. No significant reduction in defect inspection performance was found; in fact, further advantages were identified when using the FPC-based MsS. When acting as the transmitter, the innovative FPC-based MsS can cover a longer inspection length of strand. When acting as the receiver, the FPC-based MsS is more sensitive to smaller defects that are impossible to detect using a hard coil MsS. Hence, the multi-layer FPC-based MsS has great potential for replacing the conventional hard coil MsS because of its convenient installation, and ease of fitting to

Triple Halo Coil: Development and Comparison with Other TMS Coils

Science.gov (United States)

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.

Method and apparatus for making superconductive magnet coils

Science.gov (United States)

Borden, Albert R.

1985-01-01

A curved, shell-type magnet coil, adapted to be used in a superconducting magnet, is wound by providing a mandrel having a tubular cylindrical mid-portion terminating at both ends in tapered end portions formed with longitudinal slots having flexible fingers therebetween. An elongated electrical conductor is wound around an elongated oval-shaped pole island engaged with the outside of the cylindrical mid-portion, to form a multiplicity of oval-shaped turns engaged with a 180-degree segment of the mandrel. The coil turns have longitudinal portions with curved portions therebetween, engaging the tapered end portions of the mandrel. Upon completion of the winding, tapered expansion members are fully inserted into the tapered end portions, to displace the flexible fingers outwardly into a cylindrical form and to displace the curved portions of the turns into a shape conforming to such cylindrical form while also exerting increased tension upon the turns to minimize draping of the turns and to enhance the mechanical integrity of the coil. A half cylinder clamp may then be employed to clamp the coil, whereupon the coil may be solified by the use of an epoxy adhesive.

Biomaterials Made from Coiled-Coil Peptides.

Science.gov (United States)

Conticello, Vincent; Hughes, Spencer; Modlin, Charles

The development of biomaterials designed for specific applications is an important objective in personalized medicine. While the breadth and prominence of biomaterials have increased exponentially over the past decades, critical challenges remain to be addressed, particularly in the development of biomaterials that exhibit highly specific functions. These functional properties are often encoded within the molecular structure of the component molecules. Proteins, as a consequence of their structural specificity, represent useful substrates for the construction of functional biomaterials through rational design. This chapter provides an in-depth survey of biomaterials constructed from coiled-coils, one of the best-understood protein structural motifs. We discuss the utility of this structurally diverse and functionally tunable class of proteins for the creation of novel biomaterials. This discussion illustrates the progress that has been made in the development of coiled-coil biomaterials by showcasing studies that bridge the gap between the academic science and potential technological impact.

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

Science.gov (United States)

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).

Development of a new error field correction coil (C-coil) for DIII-D

International Nuclear Information System (INIS)

Robinson, J.I.; Scoville, J.T.

1995-12-01

The C-coil recently installed on the DIII-D tokamak was developed to reduce the error fields created by imperfections in the location and geometry of the existing coils used to confine, heat, and shape the plasma. First results from C-coil experiments include stable operation in a 1.6 MA plasma with a density less than 1.0 x 10 13 cm -3 , nearly a factor of three lower density than that achievable without the C-coil. The C-coil has also been used in magnetic braking of the plasma rotation and high energy particle confinement experiments. The C-coil system consists of six individual saddle coils, each 60 degree wide toroidally, spanning the midplane of the vessel with a vertical height of 1.6 m. The coils are located at a major radius of 3.2 m, just outside of the toroidal field coils. The actual shape and geometry of each coil section varied somewhat from the nominal dimensions due to the large number of obstructions to the desired coil path around the already crowded tokamak. Each coil section consists of four turns of 750 MCM insulated copper cable banded with stainless steel straps within the web of a 3 in. x 3 in. stainless steel angle frame. The C-coil structure was designed to resist peak transient radial forces (up to 1,800 Nm) exerted on the coil by the toroidal and ploidal fields. The coil frames were supported from existing poloidal field coil case brackets, coil studs, and various other structures on the tokamak

Improved Decoupling for 13C coil Arrays Using Non-Conventional Matching and Preamplifier Impedance

DEFF Research Database (Denmark)

Sanchez, Juan Diego; Johansen, Daniel Højrup; Hansen, Rie Beck

In this study, we describe a method to obtain improved preamplifier decoupling for receive-only coils. The method relies on the better decoupling obtained when coils are matched to an impedance higher than 50 . Preamplifiers with inductive imaginary impedance and low real impedance, increase...

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

Science.gov (United States)

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.

Conformational switching in the coiled-coil domains of a proteasomal ATPase regulates substrate processing.

Science.gov (United States)

Snoberger, Aaron; Brettrager, Evan J; Smith, David M

2018-06-18

Protein degradation in all domains of life requires ATPases that unfold and inject proteins into compartmentalized proteolytic chambers. Proteasomal ATPases in eukaryotes and archaea contain poorly understood N-terminally conserved coiled-coil domains. In this study, we engineer disulfide crosslinks in the coiled-coils of the archaeal proteasomal ATPase (PAN) and report that its three identical coiled-coil domains can adopt three different conformations: (1) in-register and zipped, (2) in-register and partially unzipped, and (3) out-of-register. This conformational heterogeneity conflicts with PAN's symmetrical OB-coiled-coil crystal structure but resembles the conformational heterogeneity of the 26S proteasomal ATPases' coiled-coils. Furthermore, we find that one coiled-coil can be conformationally constrained even while unfolding substrates, and conformational changes in two of the coiled-coils regulate PAN switching between resting and active states. This switching functionally mimics similar states proposed for the 26S proteasome from cryo-EM. These findings thus build a mechanistic framework to understand regulation of proteasome activity.

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

International Nuclear Information System (INIS)

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

A novel method for coil efficiency estimation: Validation with a 13C birdcage

DEFF Research Database (Denmark)

Giovannetti, Giulio; Frijia, Francesca; Hartwig, Valentina

2012-01-01

Coil efficiency, defined as the B1 magnetic field induced at a given point on the square root of supplied power P, is an important parameter that characterizes both the transmit and receive performance of the radiofrequency (RF) coil. Maximizing coil efficiency will maximize also the signal......-to-noise ratio. In this work, we propose a novel method for RF coil efficiency estimation based on the use of a perturbing loop. The proposed method consists of loading the coil with a known resistor by inductive coupling and measuring the quality factor with and without the load. We tested the method...... by measuring the efficiency of a 13C birdcage coil tuned at 32.13 MHz and verified its accuracy by comparing the results with the nuclear magnetic resonance nutation experiment. The method allows coil performance characterization in a short time and with great accuracy, and it can be used both on the bench...

Superconducting magnetic coil

Science.gov (United States)

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.

Magnetic resonance dacryocystography: comparison between conventional surface coils and microscopic coils

International Nuclear Information System (INIS)

Abreu Junior, Luiz de; Wolosker, Angela Maria Borri; Borri, Maria Lucia; Galvao Filho, Mario de Melo; Hartmann, Luiz Guilherme de Carvalho; D'Ippolito, Giuseppe; Castro, Claudio Campi de

2008-01-01

Objective: Magnetic resonance imaging has been utilized in the evaluation of the lacrimal apparatus with some advantages over conventional dacryocystography. The present study was aimed at acquiring high resolution images utilizing microscopic coils for evaluating typical structures of the lacrimal apparatus as compared with the findings observed with conventional surface coils. Materials and methods: Five asymptomatic volunteers with no history of epiphora were submitted to high-field magnetic resonance imaging with microscopic and conventional surface coils, and STIR sequence after instillation of saline solution. The definition of normal anatomic structures of lacrimal apparatuses was compared utilizing conventional and microscopic surface coils. Based on a consensual scoring system, the mean values for each structure were calculated by two observers. Results: In 90% of cases, higher scores were attributed to images acquired with the microscopic coil. On average, a 1.17 point increase was observed in the scoring of anatomic structures imaged with the microscopic coil. Additionally, a subjective improvement was observed in the signal-to-noise ratio with the microscopic coil. Conclusion: Magnetic resonance dacryocystography with microscopic coils is the appropriate method for evaluating the lacrimal apparatus, providing images with better quality as compared with those acquired with conventional surface coils. (author)

Design Optimization for a Maglev System Employing Flux Eliminating Coils

Science.gov (United States)

Davey, Kent R.

1996-01-01

Flux eliminating coils have received no little attention over the past thirty years as an alternative for realizing lift in a MAGLEV system. When the magnets on board the vehicle are displaced from the equilibrium or null flux point of these coils, they induce current in those coils which act to restore the coil to its null flux or centerline position. The question being addressed in this paper is that of how to choose the best coil for a given system. What appears at first glance to be an innocent question is in fact one that is actually quite involved, encompassing both the global economics and physics of the system. The real key in analyzing that question is to derive an optimization index or functional which represents the cost of the system subject to constraints, the primary constraint being that the vehicle lift itself at a certain threshold speed. Outlined in this paper is one scenario for realizing a total system design which uses sequential quadratic programming techniques.

Compact stellarator coils

International Nuclear Information System (INIS)

Pomphrey, N.; Berry, L.A.; Boozer, A.H.

2001-01-01

Experimental devices to study the physics of high-beta (β>∼4%), low aspect ratio (A<∼4.5) stellarator plasmas require coils that will produce plasmas satisfying a set of physics goals, provide experimental flexibility, and be practical to construct. In the course of designing a flexible coil set for the National Compact Stellarator Experiment, we have made several innovations that may be useful in future stellarator design efforts. These include: the use of Singular Value Decomposition methods for obtaining families of smooth current potentials on distant coil winding surfaces from which low current density solutions may be identified; the use of a Control Matrix Method for identifying which few of the many detailed elements of the stellarator boundary must be targeted if a coil set is to provide fields to control the essential physics of the plasma; the use of Genetic Algorithms for choosing an optimal set of discrete coils from a continuum of potential contours; the evaluation of alternate coil topologies for balancing the tradeoff between physics objective and engineering constraints; the development of a new coil optimization code for designing modular coils, and the identification of a 'natural' basis for describing current sheet distributions. (author)

Plasmodium vivax antigen discovery based on alpha-helical coiled coil protein motif

DEFF Research Database (Denmark)

Céspedes, Nora; Habel, Catherine; Lopez-Perez, Mary

2014-01-01

Protein α-helical coiled coil structures that elicit antibody responses, which block critical functions of medically important microorganisms, represent a means for vaccine development. By using bioinformatics algorithms, a total of 50 antigens with α-helical coiled coil motifs orthologous to Pla...

NCSX Trim Coil Design

International Nuclear Information System (INIS)

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

2009-01-01

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

Composite coils for toroidal field coils and method of using same

International Nuclear Information System (INIS)

Perkins, R. G.; Trujillo, S. M.

1985-01-01

A composite toroidal field (TF) generating means consisting of segmented magnetic coil windings is disclosed. Each coil winding of the TF generating means consists of a copper or copper alloy conductor segment and an aluminum or aluminum alloy conductor segment. The conductor segments are joined at a high strength, low electrical resistance joint and the joint may either be a mechanical or metallurgical one. The use of the aluminum or aluminum alloy conductor segments improves the neutron economy of the reactor with which the TF coil is associated and reduces TF coil nuclear heating and heating gradients, and activation in the TF coils

Multiple coil pulsed magnetic resonance method for measuring cold SSC dipole magnet field quality

International Nuclear Information System (INIS)

Clark, W.G.; Moore, J.M.; Wong, W.H.

1990-01-01

The operating principles and system architecture for a method to measure the magnetic field multipole expansion coefficients are described in the context of the needs of SSC dipole magnets. The operation of an 8-coil prototype system is discussed. Several of the most important technological issues that influence the design are identified and the basis of their resolution is explained. The new features of a 32-coil system presently under construction are described, along with estimates of its requirements for measurement time and data storage capacity

Outcomes with single-coil versus dual-coil implantable cardioverter defibrillators: a meta-analysis.

Science.gov (United States)

Sunderland, Nicholas; Kaura, Amit; Murgatroyd, Francis; Dhillon, Para; Scott, Paul A

2018-03-01

Dual-coil implantable cardioverter defibrillator (ICD) leads have traditionally been used over single-coil leads due to concerns regarding high defibrillation thresholds (DFT) and consequent poor shock efficacy. However, accumulating evidence suggests that this position may be unfounded and that dual-coil leads may also be associated with higher complication rates during lead extraction. This meta-analysis collates data comparing dual- and single-coil ICD leads. Electronic databases were systematically searched for randomized controlled trials (RCT) and non-randomized studies comparing single-coil and dual-coil leads. The mean differences in DFT and summary estimates of the odds-ratio (OR) for first-shock efficacy and the hazard-ratio (HR) for all-cause mortality were calculated using random effects models. Eighteen studies including a total of 138,124 patients were identified. Dual-coil leads were associated with a lower DFT compared to single coil leads (mean difference -0.83J; 95% confidence interval [CI] -1.39--0.27; P = 0.004). There was no difference in the first-shock success rate with dual-coil compared to single-coil leads (OR 0.74; 95%CI 0.45-1.21; P=0.22). There was a significantly lower risk of all-cause mortality associated with single-coil leads (HR 0.91; 95%CI 0.86-0.95; P dual-coil leads. The mortality benefit with single-coil leads most likely represents patient selection bias. Given the increased risk and complexity of extracting dual-coil leads, centres should strongly consider single-coil ICD leads as the lead of choice for routine new left-sided ICD implants. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

HydroSoft coil versus HydroCoil for endovascular aneurysm occlusion study: A single center experience

International Nuclear Information System (INIS)

Guo Xinbin; Fan Yimu; Zhang Jianning

2011-01-01

Background and purpose: The HydroCoil Embolic System (HES) was developed to reduce recurrences of aneurysms relative to platinum coils. But the HydroCoil Embolic System was characterized with many limitations. The manufacturer had recognized the challenge and recently a new design of hydrogel-coated coil-HydroSoft has become available in the market as the new generation HydroCoil. We reported our initial experience using HydroSoft coil versus HydroCoil in our center. Methods: 75 aneurysms embolized primarily using HydroSoft Coils from July 2008 to May 2009 were compared with 66 volume- and shape-matched aneurysms treated with HydroCoils from March 2006 to August 2008. Outcome measures included length and number of coils used, contrast volume, and length of hospital stay. During embolization, a stable framework was first established with bare coils, and hydrogel-coated coils were used subsequently to increase the packing density. Follow-up angiographic results 6 months after treatment were evaluated among some of the patients. Results: Successful coil embolization was achieved in all patients. There were no differences in average total coil length used per aneurysm. There were no differences in length of hospital stay and packing density. HydroSoft coils were more suitable using as the finishing or final coil. HydroSoft coil decreased the procedure-related retreated rates, and aneurysm packing was finished with soft, flexible HydroSoft coil and decreased the neck remnant rates. Follow-up angiography in HydroSoft-treated patients at 6 months revealed aneurysm stability without significant residual neck. Conclusions: HydroSoft coil allowed us to deploy coated coils with good packing density. A slight expansion of these coils at the neck can be expected to reduce neck remnant and potentially inhibit recurrence.

Coiled-coil forming peptides for the induction of silver nanoparticles

International Nuclear Information System (INIS)

Božič Abram, Sabina; Aupič, Jana; Dražić, Goran; Gradišar, Helena; Jerala, Roman

2016-01-01

Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at around 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.

Coiled-coil forming peptides for the induction of silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Božič Abram, Sabina [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Graduate School of Biomedicine, University of Ljubljana, Ljubljana 1000 (Slovenia); Aupič, Jana [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Doctoral Programme in Chemical Sciences, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000 (Slovenia); Dražić, Goran [Laboratory for Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Gradišar, Helena [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); EN-FIST, Centre of Excellence, Trg Osvobodilne fronte 13, Ljubljana 1000 (Slovenia); Jerala, Roman, E-mail: roman.jerala@ki.si [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); EN-FIST, Centre of Excellence, Trg Osvobodilne fronte 13, Ljubljana 1000 (Slovenia)

2016-04-08

Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at around 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.

Automated de novo phasing and model building of coiled-coil proteins.

Science.gov (United States)

Rämisch, Sebastian; Lizatović, Robert; André, Ingemar

2015-03-01

Models generated by de novo structure prediction can be very useful starting points for molecular replacement for systems where suitable structural homologues cannot be readily identified. Protein-protein complexes and de novo-designed proteins are examples of systems that can be challenging to phase. In this study, the potential of de novo models of protein complexes for use as starting points for molecular replacement is investigated. The approach is demonstrated using homomeric coiled-coil proteins, which are excellent model systems for oligomeric systems. Despite the stereotypical fold of coiled coils, initial phase estimation can be difficult and many structures have to be solved with experimental phasing. A method was developed for automatic structure determination of homomeric coiled coils from X-ray diffraction data. In a benchmark set of 24 coiled coils, ranging from dimers to pentamers with resolutions down to 2.5 Å, 22 systems were automatically solved, 11 of which had previously been solved by experimental phasing. The generated models contained 71-103% of the residues present in the deposited structures, had the correct sequence and had free R values that deviated on average by 0.01 from those of the respective reference structures. The electron-density maps were of sufficient quality that only minor manual editing was necessary to produce final structures. The method, named CCsolve, combines methods for de novo structure prediction, initial phase estimation and automated model building into one pipeline. CCsolve is robust against errors in the initial models and can readily be modified to make use of alternative crystallographic software. The results demonstrate the feasibility of de novo phasing of protein-protein complexes, an approach that could also be employed for other small systems beyond coiled coils.

Performance Enhancement of Land Vehicle Positioning Using Multiple GPS Receivers in an Urban Area

Directory of Open Access Journals (Sweden)

Jong-Hwa Song

2016-10-01

Full Text Available The Global Positioning System (GPS is the most widely used navigation system in land vehicle applications. In urban areas, the GPS suffers from insufficient signal strength, multipath propagation and non-line-of-sight (NLOS errors, so it thus becomes difficult to obtain accurate and reliable position information. In this paper, an integration algorithm for multiple receivers is proposed to enhance the positioning performance of GPS for land vehicles in urban areas. The pseudoranges of multiple receivers are integrated based on a tightly coupled approach, and erroneous measurements are detected by testing the closeness of the pseudoranges. In order to fairly compare the pseudoranges, GPS errors and terms arising due to the differences between the positions of the receivers need to be compensated. The double-difference technique is used to eliminate GPS errors in the pseudoranges, and the geometrical distance is corrected by projecting the baseline vector between pairs of receivers. In order to test and analyze the proposed algorithm, an experiment involving live data was performed. The positioning performance of the algorithm was compared with that of the receiver autonomous integrity monitoring (RAIM-based integration algorithm for multiple receivers. The test results showed that the proposed algorithm yields more accurate position information in urban areas.

Design of a Nested Eight-Channel Sodium and Four-Channel Proton Coil for 7 Tesla Knee Imaging

Science.gov (United States)

Brown, Ryan; Madelin, Guillaume; Lattanzi, Riccardo; Chang, Gregory; Regatte, Ravinder R.; Sodickson, Daniel K.; Wiggins, Graham C.

2012-01-01

The critical design aim for a dual-tuned sodium/proton coil is to maximize sodium sensitivity and transmit field (B1+) homogeneity while simultaneously providing adequate proton sensitivity and homogeneity. While most dual-frequency coils utilize lossy high-impedance trap circuits or PIN diodes to allow dual-resonance, we explored a nested-coil design for sodium/proton knee imaging at 7T. A stand-alone eight-channel sodium receive array was implemented without standard dual-resonance circuitry to provide improved sodium signal-to-noise ratio (SNR) over a volume coil. A detunable sodium birdcage was added for homogeneous sodium excitation and a four-channel proton transmit-receive array was added to provide anatomical reference imaging and B0 shimming capability. Both modules were implemented with minimal disturbance to the eight-channel sodium array by managing their respective resonances and geometrical arrangement. In vivo sodium SNR was 1.2 to 1.7 times greater in the developed eight-channel array than in a mono-nuclear sodium birdcage coil, while the developed four-channel proton array provided SNR similar to that of a commercial mono-nuclear proton birdcage coil. PMID:22887123

Conception of Brownian coil

OpenAIRE

Zhang, Jiayuan

2018-01-01

This article proposes a conception of Brownian coil. Brownian coil is a tiny coil with the same size of pollen. Once immersed into designed magnetic field and liquid, the coil will be moved and deformed macroscopically, due to the microscopic thermodynamic molecular collisions. Such deformation and movement will change the magnetic flux through the coil, by which an ElectroMotive Force (EMF) is produced. In this work, Brownian heat exchanger and Brownian generator are further designed to tran...

Plasma confinement apparatus using solenoidal and mirror coils

Science.gov (United States)

Fowler, T. Kenneth; Condit, William C.

1979-01-01

A plasma confinement apparatus, wherein multiple magnetic mirror cells are linked by magnetic field lines inside of a solenoid with the mirroring regions for adjacent magnetic mirror cells each formed by a separate mirror coil inside of the solenoid. The magnetic mirror cells may be field reversed.

Historical review: another 50th anniversary--new periodicities in coiled coils.

Science.gov (United States)

Gruber, Markus; Lupas, Andrei N

2003-12-01

In 1953, Francis Crick and Linus Pauling both proposed models of supercoiled alpha helices ('coiled coils') for the structure of keratin. These were the first attempts at modelling the tertiary structure of a protein. Crick emphasized the packing mode of the side-chains ('knobs-into-holes'), which required a periodicity of seven residues over two helical turns (7/2) and a supercoil in the opposite sense of the constituent helices. By contrast, Pauling envisaged a broader set of periodicities (4/1, 7/2, 18/5, 15/4, 11/3) and supercoils of both senses. Crick's model became canonical and the 'heptad repeat' essentially synonymous with coiled coils, but 50 years later new crystal structures and protein sequences show that the less common periodicities envisaged by Pauling also occur in coiled coils, adding a variant packing mode ('knobs-to-knobs') to the standard model. Pauling's laboratory notebooks suggest that he searched unsuccessfully for this packing mode in 1953.

Coiled-Coil Proteins Facilitated the Functional Expansion of the Centrosome

Science.gov (United States)

Kuhn, Michael; Hyman, Anthony A.; Beyer, Andreas

2014-01-01

Repurposing existing proteins for new cellular functions is recognized as a main mechanism of evolutionary innovation, but its role in organelle evolution is unclear. Here, we explore the mechanisms that led to the evolution of the centrosome, an ancestral eukaryotic organelle that expanded its functional repertoire through the course of evolution. We developed a refined sequence alignment technique that is more sensitive to coiled coil proteins, which are abundant in the centrosome. For proteins with high coiled-coil content, our algorithm identified 17% more reciprocal best hits than BLAST. Analyzing 108 eukaryotic genomes, we traced the evolutionary history of centrosome proteins. In order to assess how these proteins formed the centrosome and adopted new functions, we computationally emulated evolution by iteratively removing the most recently evolved proteins from the centrosomal protein interaction network. Coiled-coil proteins that first appeared in the animal–fungi ancestor act as scaffolds and recruit ancestral eukaryotic proteins such as kinases and phosphatases to the centrosome. This process created a signaling hub that is crucial for multicellular development. Our results demonstrate how ancient proteins can be co-opted to different cellular localizations, thereby becoming involved in novel functions. PMID:24901223

CCBuilder 2.0: Powerful and accessible coiled-coil modeling.

Science.gov (United States)

Wood, Christopher W; Woolfson, Derek N

2018-01-01

The increased availability of user-friendly and accessible computational tools for biomolecular modeling would expand the reach and application of biomolecular engineering and design. For protein modeling, one key challenge is to reduce the complexities of 3D protein folds to sets of parametric equations that nonetheless capture the salient features of these structures accurately. At present, this is possible for a subset of proteins, namely, repeat proteins. The α-helical coiled coil provides one such example, which represents ≈ 3-5% of all known protein-encoding regions of DNA. Coiled coils are bundles of α helices that can be described by a small set of structural parameters. Here we describe how this parametric description can be implemented in an easy-to-use web application, called CCBuilder 2.0, for modeling and optimizing both α-helical coiled coils and polyproline-based collagen triple helices. This has many applications from providing models to aid molecular replacement for X-ray crystallography, in silico model building and engineering of natural and designed protein assemblies, and through to the creation of completely de novo "dark matter" protein structures. CCBuilder 2.0 is available as a web-based application, the code for which is open-source and can be downloaded freely. http://coiledcoils.chm.bris.ac.uk/ccbuilder2. We have created CCBuilder 2.0, an easy to use web-based application that can model structures for a whole class of proteins, the α-helical coiled coil, which is estimated to account for 3-5% of all proteins in nature. CCBuilder 2.0 will be of use to a large number of protein scientists engaged in fundamental studies, such as protein structure determination, through to more-applied research including designing and engineering novel proteins that have potential applications in biotechnology. © 2017 The Authors Protein Science published by Wiley Periodicals, Inc. on behalf of The Protein Society.

HydroCoil as an adjuvant to bare platinum coil treatment of 100 cerebral aneurysms

International Nuclear Information System (INIS)

Fanning, Noel F.; Berentei, Zsolt; Brennan, Paul R.; Thornton, John

2007-01-01

Introduction The overall safety of the HydroCoil, an expansile hybrid hydrogel-platinum coil, is unknown. We report a prospective observational study of our first 100 cerebral aneurysms treated with HydroCoils, focusing on safety and initial efficacy.Methods Indications, procedural complications, clinical and angiographic outcomes were recorded. Packing density, number of coils deployed and angiographic results were compared with those in a matched control group of 100 aneurysms treated solely with bare platinum coils. HydroCoil complication rates were compared to bare platinum coil rates at our institution and in published series. Results Adjuvant HydroCoil treatment led to increased mean percentage aneurysm filling compared to controls (50 ± 21% versus 27 ± 13%, P < 0.001). Immediate posttreatment angiographic results showed significantly (P < 0.001) more complete occlusions and fewer incomplete (<95%) occlusions compared to controls. Intermediate follow-up angiograms (median 7.5 months) in 63 aneurysms showed a trend towards fewer incomplete occlusions with HydroCoil treatment. There were significantly fewer major recurrences with HydroCoil treatment compared to the control treatment (9.5% versus 22.6%, P 0.046). In the adjuvant HydroCoil group, major recurrent aneurysms had significantly less percentage volume packing with HydroCoils than non-recurrent aneurysms (50.3 ± 5.0% versus 65.3 ± 18.0%, P = 0.04). There was a 12% procedural complication rate, 6% procedural morbidity and 1% mortality rate, similar to institutional and reported bare platinum coil complication rates.Conclusion HydroCoils can be safely deployed with a similar complication rate to bare platinum coils. They result in improved aneurysm filling. Intermediate follow-up angiography showed significantly fewer major recurrences. Long-term follow-up is required to confirm initial improved stability. (orig.)

NET model coil test possibilities

International Nuclear Information System (INIS)

Erb, J.; Gruenhagen, A.; Herz, W.; Jentzsch, K.; Komarek, P.; Lotz, E.; Malang, S.; Maurer, W.; Noether, G.; Ulbricht, A.; Vogt, A.; Zahn, G.; Horvath, I.; Kwasnitza, K.; Marinucci, C.; Pasztor, G.; Sborchia, C.; Weymuth, P.; Peters, A.; Roeterdink, A.

1987-11-01

A single full size coil for NET/INTOR represents an investment of the order of 40 MUC (Million Unit Costs). Before such an amount of money or even more for the 16 TF coils is invested as much risks as possible must be eliminated by a comprehensive development programme. In the course of such a programme a coil technology verification test should finally prove the feasibility of NET/INTOR TF coils. This study report is almost exclusively dealing with such a verification test by model coil testing. These coils will be built out of two Nb 3 Sn-conductors based on two concepts already under development and investigation. Two possible coil arrangements are discussed: A cluster facility, where two model coils out of the two Nb 3 TF-conductors are used, and the already tested LCT-coils producing a background field. A solenoid arrangement, where in addition to the two TF model coils another model coil out of a PF-conductor for the central PF-coils of NET/INTOR is used instead of LCT background coils. Technical advantages and disadvantages are worked out in order to compare and judge both facilities. Costs estimates and the time schedules broaden the base for a decision about the realisation of such a facility. (orig.) [de

Single-Coil Defibrillator Leads Yield Satisfactory Defibrillation Safety Margin in Hypertrophic Cardiomyopathy.

Science.gov (United States)

Okamura, Hideo; Friedman, Paul A; Inoue, Yuko; Noda, Takashi; Aiba, Takeshi; Yasuda, Satoshi; Ogawa, Hisao; Kamakura, Shiro; Kusano, Kengo; Espinosa, Raul E

2016-09-23

Single-coil defibrillator leads have gained favor because of their potential ease of extraction. However, a high defibrillation threshold remains a concern in patients with hypertrophic cardiomyopathy (HCM), and in many cases, dual-coil leads have been used for this patient group. There is little data on using single-coil leads for HCM patients. We evaluated 20 patients with HCM who received an implantable cardioverter-defibrillator (ICD) on the left side in combination with a dual-coil lead. Two sets of defibrillation tests were performed in each patient, one with the superior vena cava (SVC) coil "on" and one with the SVC coil "off". ICDs were programmed to deliver 25 joules (J) for the first attempt followed by maximum energy (35 J or 40 J). Shock impedance and shock pulse width at 25 J in each setting as well as the results of the shock were analyzed. All 25-J shocks in both settings successfully terminated ventricular fibrillation. However, shock impedance and pulse width increased substantially with the SVC coil programmed "off" compared with "on" (66.4±6.1 ohm and 14.0±1.3 ms "off" vs. 41.9±5.0 ohm and 9.3±0.8 ms "on", Psatisfactory safety margin for 35-J devices. Single-coil leads appear appropriate for left-sided implantation in this patient group. (Circ J 2016; 80: 2199-2203).

Comparison of image quality in magnetic resonance imaging of the knee at 1.5 and 3.0 Tesla using 32-channel receiver coils

International Nuclear Information System (INIS)

Schoth, F.; Kraemer, N.; Niendorf, T.; Hohl, C.; Gunther, R.W.; Krombach, G.A.

2008-01-01

We examined to what degree the visualization of anatomic structures in the human knee is improved using 3.0-T magnetic resonance imaging (MRI) and many element RF receive coils as compared to 1.5 T. We imaged 20 knees at 1.5 and 3.0 T using T2-weighted STIR, T2-weighted gradient echo, T1-weighted spin-echo, true-FISP and T2-weighted fast spin echo techniques in conjunction with 32-element RF coil arrays. The 3.0-T examination was considerably faster than its 1.5-T counterpart. A superior subjective visibility at 3.0 T vs 1.5 T was found in 27 of 50 evaluated structures (meniscus, ligaments) with the exception of true-FISP techniques. The 3.0-T examination provided a better visibility (evaluated by blinded consensus-reading by two radiologists) of small structures such as the ligamentum transversum genu. Also, cartilage was better delineated at 3.0 T. A 23% increased average signal-to-noise ratio as assessed using a temporal filter was observed at 3.0 T as compared to 1.5 T. At 3.0 T, imaging of the human knee is faster and results in a subjective visibility of anatomic structures that is superior to and competitive with 1.5 T. (orig.)

Dual coil ignition system

Energy Technology Data Exchange (ETDEWEB)

Huberts, Garlan J.; Qu, Qiuping; Czekala, Michael Damian

2017-03-28

A dual coil ignition system is provided. The dual coil ignition system includes a first inductive ignition coil including a first primary winding and a first secondary winding, and a second inductive ignition coil including a second primary winding and a second secondary winding, the second secondary winding connected in series to the first secondary winding. The dual coil ignition system further includes a diode network including a first diode and a second diode connected between the first secondary winding and the second secondary winding.

A fourth gradient to overcome slice dependent phase effects of voxel-sized coils in planar arrays.

Science.gov (United States)

Bosshard, John C; Eigenbrodt, Edwin P; McDougall, Mary P; Wright, Steven M

2010-01-01

The signals from an array of densely spaced long and narrow receive coils for MRI are complicated when the voxel size is of comparable dimension to the coil size. The RF coil causes a phase gradient across each voxel, which is dependent on the distance from the coil, resulting in a slice dependent shift of k-space. A fourth gradient coil has been implemented and used with the system's gradient set to create a gradient field which varies with slice. The gradients are pulsed together to impart a slice dependent phase gradient to compensate for the slice dependent phase due to the RF coils. However the non-linearity in the fourth gradient which creates the desired slice dependency also results in a through-slice phase ramp, which disturbs normal slice refocusing and leads to additional signal cancelation and reduced field of view. This paper discusses the benefits and limitations of using a fourth gradient coil to compensate for the phase due to RF coils.

Plasma confinement apparatus using solenoidal and mirror coils

International Nuclear Information System (INIS)

Fowler, T.K.; Condit, W.C.

1979-01-01

A plasma confinement apparatus is described, wherein multiple magnetic mirror cells are linked by magnetic field lines inside of a solenoid with the mirroring regions for adjacent magnetic mirror cells each formed by a separate mirror coil inside of the solenoid. The magnetic mirror cells may be field reversed

Coil Migration through a Neuroform 3 Stent during Endovascular Coiling. A Case Report.

LENUS (Irish Health Repository)

O'Hare, A

2009-07-29

Summary: A 43-year-old woman attended for stent assisted coiling. A Neuroform 30 x 4.5 mm stent had been successfully placed over the left periophthalmic aneurysm. During the coiling the first coil migrated through the crowns in the stent, lodging at the MCA bifurcation. We believe that the coil herniated through the overlying stent due to the carotid siphon curvature and the open cell design. Furthermore the distal markers of the stent impeded coil extraction with a MERCI device.

A Flexible Nested Sodium and Proton Coil Array with Wideband Matching for Knee Cartilage MRI at 3 Tesla

Science.gov (United States)

Brown, Ryan; Lakshmanan, Karthik; Madelin, Guillaume; Alon, Leeor; Chang, Gregory; Sodickson, Daniel K.; Regatte, Ravinder R.; Wiggins, Graham C.

2015-01-01

Purpose We describe a 6×2 channel sodium/proton array for knee MRI at 3 Tesla. Multi-element coil arrays are desirable because of well-known signal-to-noise ratio advantages over volume and single-element coils. However, low coil-tissue coupling that is characteristic of coils operating at low frequency can make the potential gains from a phased array difficult to realize. Methods The issue of low coil-tissue coupling in the developed six channel sodium receive array was addressed by implementing 1) a mechanically flexible former to minimize coil-to-tissue distance and reduce the overall diameter of the array and 2) a wideband matching scheme that counteracts preamplifier noise degradation caused by coil coupling and a high quality factor. The sodium array was complemented with a nested proton array to enable standard MRI. Results The wideband matching scheme and tight-fitting mechanical design contributed to greater than 30% central SNR gain on the sodium module over a mono-nuclear sodium birdcage coil, while the performance of the proton module was sufficient for clinical imaging. Conclusion We expect the strategies presented in this work to be generally relevant in high density receive arrays, particularly in x-nuclei or small animal applications, or in those where the array is distant from the targeted tissue. PMID:26502310

TFTR toroidal field coil design

International Nuclear Information System (INIS)

Smith, G.E.; Punchard, W.F.B.

1977-01-01

The design of the Tokamak Fusion Test Reactor (TFTR) Toroidal Field (TF) magnetic coils is described. The TF coil is a 44-turn, spiral-wound, two-pancake, water-cooled configuration which, at a coil current of 73.3 kiloamperes, produces a 5.2-Tesla field at a major radius of 2.48 meters. The magnetic coils are installed in titanium cases, which transmit the loads generated in the coils to the adjacent supporting structure. The TFTR utilizes 20 of these coils, positioned radially at 18 0 intervals, to provide the required toroidal field. Because it is very highly loaded and subject to tight volume constraints within the machine, the coil presents unique design problems. The TF coil requirements are summarized, the coil configuration is described, and the problems highlighted which have been encountered thus far in the coil design effort, together with the development tests which have been undertaken to verify the design

NCSX Toroidal Field Coil Design

International Nuclear Information System (INIS)

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

2005-01-01

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

Transcatheter Coil Embolization of Splenic Artery Aneurysm

International Nuclear Information System (INIS)

Yamamoto, Satoshi; Hirota, Shozo; Maeda, Hiroaki; Achiwa, Sachiko; Arai, Keisuke; Kobayashi, Kaoru; Nakao, Norio

2008-01-01

The purpose of this study was to evaluate clinical results and technical problems of transcatheter coil embolization for splenic artery aneurysm. Subjects were 16 patients (8 men, 8 women; age range, 40-80 years) who underwent transcatheter embolization for splenic artery aneurysm (14 true aneurysms, 2 false aneurysms) at one of our hospitals during the period January 1997 through July 2005. Two aneurysms (12.5%) were diagnosed at the time of rupture. Multiple splenic aneurysms were found in seven patients. Aneurysms were classified by site as proximal (or strictly ostial) (n = 3), middle (n = 3), or hilar (n = 10). The indication for transcatheter arterial embolization was a false or true aneurysm 20 mm in diameter. Embolic materials were fibered coils and interlocking detachable coils. Embolization was performed by the isolation technique, the packing technique, or both. Technically, all aneurysms were devascularized without severe complications. Embolized aneurysms were 6-40 mm in diameter (mean, 25 mm). Overall, the primary technical success rate was 88% (14 of 16 patients). In the remaining 2 patients (12.5%), partial recanalization occurred, and re-embolization was performed. The secondary technical success rate was 100%. Seven (44%) of the 16 study patients suffered partial splenic infarction. Intrasplenic branching originating from the aneurysm was observed in five patients. We conclude that transcatheter coil embolization should be the initial treatment of choice for splenic artery aneurysm

Four signature motifs define the first class of structurally related large coiled-coil proteins in plants.

Directory of Open Access Journals (Sweden)

Meier Iris

2002-04-01

Full Text Available Abstract Background Animal and yeast proteins containing long coiled-coil domains are involved in attaching other proteins to the large, solid-state components of the cell. One subgroup of long coiled-coil proteins are the nuclear lamins, which are involved in attaching chromatin to the nuclear envelope and have recently been implicated in inherited human diseases. In contrast to other eukaryotes, long coiled-coil proteins have been barely investigated in plants. Results We have searched the completed Arabidopsis genome and have identified a family of structurally related long coiled-coil proteins. Filament-like plant proteins (FPP were identified by sequence similarity to a tomato cDNA that encodes a coiled-coil protein which interacts with the nuclear envelope-associated protein, MAF1. The FPP family is defined by four novel unique sequence motifs and by two clusters of long coiled-coil domains separated by a non-coiled-coil linker. All family members are expressed in a variety of Arabidopsis tissues. A homolog sharing the structural features was identified in the monocot rice, indicating conservation among angiosperms. Conclusion Except for myosins, this is the first characterization of a family of long coiled-coil proteins in plants. The tomato homolog of the FPP family binds in a yeast two-hybrid assay to a nuclear envelope-associated protein. This might suggest that FPP family members function in nuclear envelope biology. Because the full Arabidopsis genome does not appear to contain genes for lamins, it is of interest to investigate other long coiled-coil proteins, which might functionally replace lamins in the plant kingdom.

Design and application of surface coils for MR imaging with consideration of patient safety

International Nuclear Information System (INIS)

Bader, R.; Zabel, H.J.; Gehrig, J.; Lorenz, W.J.

1987-01-01

Problems concerning the safety of the patient have arisen by increasing the magnetic field for MR imaging and MR spectroscopy up to 2 T. High electric potentials result on the radio frequency (RF) that antennas in some cases are situated directly on or even inside the body. Transmit pulses can induce high voltages and currents in a separate receiver coil being resonant. Intensive RF fields emerging from the receiver coil may severely heat the conductive body tissue. Principles for suppressing the induced voltages and for detuning the antenna are described. General rules for the design of antennas and their application are discussed

On modular stellarator reactor coils

International Nuclear Information System (INIS)

Rau, F.; Harmeyer, E.; Kisslinger, J.; Wobig, H.

1985-01-01

Modular twisted coils are discussed which produce magnetic fields of the Advanced Stellarator WENDELSTEIN VII-AS type. Reducing the number coils/FP offers advantage for maintenance of coils, but increases the magnetic ripple and B m /B o . Computation of force densities within the coils of ASR and ASB yield local maximum values of about 80 and 180 MN/m 3 , respectively. A system of mutual coil support is being developed. Twisted coils in helical arrangement provide a reactor-sized HELIAC system. In order to reduce the magnetic ripple, a large number of 14 coils/FP in special arrangement is used

Feasible approach of contactless power transfer technology combined with HTS coils based on electromagnetic resonance coupling

International Nuclear Information System (INIS)

Chang, Yoon Do; Yim, Seong Woo; Hwang, Si Dole

2013-01-01

The contactless power transfer (CPT) systems have been recently gaining popularity widely since it is an available option to realize the power delivery and storage with connector-free devices across a large air gap. Especially, the CPT with electromagnetic resonance coupling method is possible to exchange energy within 2 m efficiently. However, the power transfer efficiency of CPT in commercialized products has been limited because the impedance matching of coupled coils is sensitive. As a reasonable approach, we combined the CPT system with HTS wire technology and called as, superconducting contactless power transfer (SUCPT) system. Since the superconducting coils have an enough current density, the superconducting antenna and receiver coils at CPT system have a merit to deliver and receive a mass amount of electric energy. In this paper, we present the feasibility of the SUCPT system and examine the transmission properties of SUCPT phenomenon between room temperature and very low temperature at 77 K as long as the receiver is within 1.0 m distance.

Quadruple Cone Coil with improved focality than Figure-8 coil in Transcranial Magnetic Stimulation

Science.gov (United States)

Rastogi, Priyam; Lee, Erik G.; Hadimani, Ravi L.; Jiles, David C.

Transcranial Magnetic Stimulation (TMS) is a non-invasive therapy which uses a time varying magnetic field to induce an electric field in the brain and to cause neuron depolarization. Magnetic coils play an important role in the TMS therapy since their coil geometry determines the focality and penetration's depth of the induced electric field in the brain. Quadruple Cone Coil (QCC) is a novel coil with an improved focality when compared to commercial Figure-8 coil. The results of this newly designed QCC coil are compared with the Figure-8 coil at two different positions of the head - vertex and dorsolateral prefrontal cortex, over the 50 anatomically realistic MRI derived head models. Parameters such as volume of stimulation, maximum electric, area of stimulation and location of maximum electric field are determined with the help of computer modelling of both coils. There is a decrease in volume of brain stimulated by 11.6 % and a modest improvement of 8 % in the location of maximum electric field due to QCC in comparison to the Figure-8 coil. The Carver Charitable Trust and The Galloway Foundation.

Design of a coil sensor for time domain electromagnetic system for uranium exploration

International Nuclear Information System (INIS)

Keshwani, R.T.; Bhattacharya, S.

2011-01-01

Time domain electromagnetic system is used for exploration of deep seated deposits under the Earth surface. The basic principle is to set up eddy currents in conductors using pulsed excited transmitter coil during on time of a pulse. The decay time of eddy currents during off time of a pulse is a function conductivity, permeability and depth of conductor located under the Earth surface. The technology is being developed to carry out exploration of mineral deposits (basically uranium) under the Earth surface. The decay of eddy currents is eddy using J coil sensor located coplanar with the transmitter coil. The depth upto which successful exploration can be carried is strong function of design of receiver coil. The design parameters include number of turns, bandwidth, stray capacitance and resistance of a coil. This paper describes various designs tried out and their characterization results. Field results for a ground based system developed are also described. (author)

Fine-tuning of protein domain boundary by minimizing potential coiled coil regions

International Nuclear Information System (INIS)

Iwaya, Naoko; Goda, Natsuko; Unzai, Satoru; Fujiwara, Kenichiro; Tanaka, Toshiki; Tomii, Kentaro; Tochio, Hidehito; Shirakawa, Masahiro; Hiroaki, Hidekazu

2007-01-01

Structural determination of individual protein domains isolated from multidomain proteins is a common approach in the post-genomic era. Novel and thus uncharacterized domains liberated from intact proteins often self-associate due to incorrectly defined domain boundaries. Self-association results in missing signals, poor signal dispersion and a low signal-to-noise ratio in 1 H- 15 N HSQC spectra. We have found that a putative, non-canonical coiled coil region close to a domain boundary can cause transient hydrophobic self-association and monomer-dimer equilibrium in solution. Here we propose a rational method to predict putative coiled coil regions adjacent to the globular core domain using the program COILS. Except for the amino acid sequence, no preexisting knowledge concerning the domain is required. A small number of mutant proteins with a minimized coiled coil region have been rationally designed and tested. The engineered domains exhibit decreased self-association as assessed by 1 H- 15 N HSQC spectra with improved peak dispersion and sharper cross peaks. Two successful examples of isolating novel N-terminal domains from AAA-ATPases are demonstrated. Our method is useful for the experimental determination of domain boundaries suited for structural genomics studies

Fine-tuning of protein domain boundary by minimizing potential coiled coil regions.

Science.gov (United States)

Iwaya, Naoko; Goda, Natsuko; Unzai, Satoru; Fujiwara, Kenichiro; Tanaka, Toshiki; Tomii, Kentaro; Tochio, Hidehito; Shirakawa, Masahiro; Hiroaki, Hidekazu

2007-01-01

Structural determination of individual protein domains isolated from multidomain proteins is a common approach in the post-genomic era. Novel and thus uncharacterized domains liberated from intact proteins often self-associate due to incorrectly defined domain boundaries. Self-association results in missing signals, poor signal dispersion and a low signal-to-noise ratio in (1)H-(15)N HSQC spectra. We have found that a putative, non-canonical coiled coil region close to a domain boundary can cause transient hydrophobic self-association and monomer-dimer equilibrium in solution. Here we propose a rational method to predict putative coiled coil regions adjacent to the globular core domain using the program COILS. Except for the amino acid sequence, no preexisting knowledge concerning the domain is required. A small number of mutant proteins with a minimized coiled coil region have been rationally designed and tested. The engineered domains exhibit decreased self-association as assessed by (1)H-(15)N HSQC spectra with improved peak dispersion and sharper cross peaks. Two successful examples of isolating novel N-terminal domains from AAA-ATPases are demonstrated. Our method is useful for the experimental determination of domain boundaries suited for structural genomics studies.

Characteristics analysis on a superconductor resonance coil WPT system according to cooling vessel materials in different distances

International Nuclear Information System (INIS)

Jeong, In-Sung; Lee, Yu-Kyeong; Choi, Hyo-Sang

2016-01-01

Highlights: • WPT using the superconductor coil was needed research for cooling vessel. FRP, bakelite, polystyrene, aluminum, and iron were applied as the cooling vessel material to analyze the WPT distance efficiency. • When the distance between the transmitter and receiver coils was 2000 mm, FRP being used for the cooling vessel made the transmission efficiency higher than any other materials. The efficiency and distance of sending power can be improved in the superconductor coil if the cooling vessel is made with FRP. - Abstract: The interest in wireless power transfer (WPT) that can send power without using wires has been increasing recently. Especially, there is a great interest in the wireless power devices for portable IT devices. The WPT devices that have been developed so far use the magnetic induction method, and they are not active due to their distance problem. A magnetic resonance WPT method was developed and has been actively researched to resolve this problem. A superconductor coil was applied in this study to increase the efficiency of the magnetic resonance WPT. FRP, bakelite, polystyrene, aluminum, and iron were applied as the cooling vessel material to analyze the WPT distance. The distance between the transmitter and receiver coils started from 800 mm and was increased by 200 mm. The reflection coefficient was measured at each distance. As a result, FRP, bakelite, plastic PVC, polystyrene of the reflection coefficient was similar. From among these FRP being used for the cooling vessel made the transmission characteristics higher than any other materials when the distance between the transmitter and receiver coils was 2,000 mm. On the other hand, the reflection coefficient dropped when iron was used. It is estimated based on the experimental results that the wireless power transmission characteristics and distance of sending power can be improved in the superconductor coil if the cooling vessel is made with FRP.

Characteristics analysis on a superconductor resonance coil WPT system according to cooling vessel materials in different distances

Energy Technology Data Exchange (ETDEWEB)

Jeong, In-Sung, E-mail: no21park@hanmail.net; Lee, Yu-Kyeong; Choi, Hyo-Sang, E-mail: hyosang@chosun.ac.kr

2016-11-15

Highlights: • WPT using the superconductor coil was needed research for cooling vessel. FRP, bakelite, polystyrene, aluminum, and iron were applied as the cooling vessel material to analyze the WPT distance efficiency. • When the distance between the transmitter and receiver coils was 2000 mm, FRP being used for the cooling vessel made the transmission efficiency higher than any other materials. The efficiency and distance of sending power can be improved in the superconductor coil if the cooling vessel is made with FRP. - Abstract: The interest in wireless power transfer (WPT) that can send power without using wires has been increasing recently. Especially, there is a great interest in the wireless power devices for portable IT devices. The WPT devices that have been developed so far use the magnetic induction method, and they are not active due to their distance problem. A magnetic resonance WPT method was developed and has been actively researched to resolve this problem. A superconductor coil was applied in this study to increase the efficiency of the magnetic resonance WPT. FRP, bakelite, polystyrene, aluminum, and iron were applied as the cooling vessel material to analyze the WPT distance. The distance between the transmitter and receiver coils started from 800 mm and was increased by 200 mm. The reflection coefficient was measured at each distance. As a result, FRP, bakelite, plastic PVC, polystyrene of the reflection coefficient was similar. From among these FRP being used for the cooling vessel made the transmission characteristics higher than any other materials when the distance between the transmitter and receiver coils was 2,000 mm. On the other hand, the reflection coefficient dropped when iron was used. It is estimated based on the experimental results that the wireless power transmission characteristics and distance of sending power can be improved in the superconductor coil if the cooling vessel is made with FRP.

Immunogenicity of coiled-coil based drug-free macromolecular therapeutics

Czech Academy of Sciences Publication Activity Database

Kverka, Miloslav; Hartley, J.M.; Chu, T.W.; Yang, J.; Heidchen, R.; Kopeček, J.

2014-01-01

Roč. 35, č. 2 (2014), s. 5886-5896 ISSN 1616-0177 R&D Projects: GA MŠk(CZ) EE2.3.30.0003 Grant - others:NIH(US) GM095606 Institutional support: RVO:61388971 Keywords : coiled-coil * enantiomers * HPMA copolymer Subject RIV: EC - Immunology

Simulation of the coil winder for the superconducting supercollider

International Nuclear Information System (INIS)

Carnal, C.L.

1994-01-01

A unique apparatus has been designed to shape the magnet windings for the Superconducting Supercollider (SSC). The magnet windings of the SSC consist of conductor coils which are placed around a torus to generate a strong magnetic field within the torus. Several process variables must be controlled to demanding tolerances during the coil winding operation. The speed of conductor payout must be coordinated from a small spool through two stages of roll formers to the final coil shape on a large bobbin. The amount of plastic deformation in the conductor must be tightly controlled to pack it into the large bobbin with a certain desired force. The control problem consists of multiple interacting control loops. This paper describes a computer simulation of the coil winding apparatus. The Advanced Continuous Simulation Language (ACSL) was used to encode a mathematical model of the system. The objectives of the simulation study were to understand the dynamic behavior of the system and to explore strategies for control. Although the funding for the SSC was canceled, the results of the research and development project for construction of this unique facility will find application in other large-scale construction and manufacturing problems

CCBuilder: an interactive web-based tool for building, designing and assessing coiled-coil protein assemblies.

Science.gov (United States)

Wood, Christopher W; Bruning, Marc; Ibarra, Amaurys Á; Bartlett, Gail J; Thomson, Andrew R; Sessions, Richard B; Brady, R Leo; Woolfson, Derek N

2014-11-01

The ability to accurately model protein structures at the atomistic level underpins efforts to understand protein folding, to engineer natural proteins predictably and to design proteins de novo. Homology-based methods are well established and produce impressive results. However, these are limited to structures presented by and resolved for natural proteins. Addressing this problem more widely and deriving truly ab initio models requires mathematical descriptions for protein folds; the means to decorate these with natural, engineered or de novo sequences; and methods to score the resulting models. We present CCBuilder, a web-based application that tackles the problem for a defined but large class of protein structure, the α-helical coiled coils. CCBuilder generates coiled-coil backbones, builds side chains onto these frameworks and provides a range of metrics to measure the quality of the models. Its straightforward graphical user interface provides broad functionality that allows users to build and assess models, in which helix geometry, coiled-coil architecture and topology and protein sequence can be varied rapidly. We demonstrate the utility of CCBuilder by assembling models for 653 coiled-coil structures from the PDB, which cover >96% of the known coiled-coil types, and by generating models for rarer and de novo coiled-coil structures. CCBuilder is freely available, without registration, at http://coiledcoils.chm.bris.ac.uk/app/cc_builder/. © The Author 2014. Published by Oxford University Press.

Analysis of transmission efficiency of the superconducting resonance coil according the materials of cooling system

Energy Technology Data Exchange (ETDEWEB)

Lee, Yu Kyeong; Hwang, Jun Won; Choi, Hyo Sang [Chosun University, Gwangju (Korea, Republic of)

2016-03-15

The wireless power transfer (WPT) system using a magnetic resonance was based on magnetic resonance coupling of the transmission and the receiver coils. In these system, it is important to maintain a high quality-factor (Q-factor) to increase the transmission efficiency of WPT system. Our research team used a superconducting coil to increase the Q-factor of the magnetic resonance coil in WPT system. When the superconductor is applied in these system, we confirmed that transmission efficiency of WPT system was higher than normal conductor coil through a preceding study. The efficiency of the transmission and the receiver coil is affected by the magnetic shielding effect of materials around the coils. The magnetic shielding effect is dependent on the type, thickness, frequency, distance, shape of materials. Therefore, it is necessary to study the WPT system on the basis of these conditions. In this paper, the magnetic shield properties of the cooling system were analyzed using the High-Frequency Structure Simulation (HFSS, Ansys) program. We have used the shielding materials such as plastic, aluminum and iron, etc. As a result, when we applied the fiber reinforced polymer (FRP), the transmission efficiency of WPT was not affected because electromagnetic waves went through the FRP. On the other hand, in case of a iron and aluminum, transmission efficiency was decreased because of their electromagnetic shielding effect. Based on these results, the research to improve the transmission efficiency and reliability of WPT system is continuously necessary.

Power Loss Analysis and Comparison of Segmented and Unsegmented Energy Coupling Coils for Wireless Energy Transfer.

Science.gov (United States)

Tang, Sai Chun; McDannold, Nathan J

2015-03-01

This paper investigated the power losses of unsegmented and segmented energy coupling coils for wireless energy transfer. Four 30-cm energy coupling coils with different winding separations, conductor cross-sectional areas, and number of turns were developed. The four coils were tested in both unsegmented and segmented configurations. The winding conduction and intrawinding dielectric losses of the coils were evaluated individually based on a well-established lumped circuit model. We found that the intrawinding dielectric loss can be as much as seven times higher than the winding conduction loss at 6.78 MHz when the unsegmented coil is tightly wound. The dielectric loss of an unsegmented coil can be reduced by increasing the winding separation or reducing the number of turns, but the power transfer capability is reduced because of the reduced magnetomotive force. Coil segmentation using resonant capacitors has recently been proposed to significantly reduce the operating voltage of a coil to a safe level in wireless energy transfer for medical implants. Here, we found that it can naturally eliminate the dielectric loss. The coil segmentation method and the power loss analysis used in this paper could be applied to the transmitting, receiving, and resonant coils in two- and four-coil energy transfer systems.

Multi-Destination Cognitive Radio Relay Network with SWIPT and Multiple Primary Receivers

KAUST Repository

Al-Habob, Ahmed A.; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

2017-01-01

In this paper, we study the performance of simultaneous wireless information and power transfer (SWIPT) technique in a multi-destination dual-hop underlay cognitive relay network with multiple primary receivers. Information transmission from

Induction heating using induction coils in series-parallel circuits

Science.gov (United States)

Matsen, Marc Rollo; Geren, William Preston; Miller, Robert James; Negley, Mark Alan; Dykstra, William Chet

2017-11-14

A part is inductively heated by multiple, self-regulating induction coil circuits having susceptors, coupled together in parallel and in series with an AC power supply. Each of the circuits includes a tuning capacitor that tunes the circuit to resonate at the frequency of AC power supply.

Analytical Model and Optimized Design of Power Transmitting Coil for Inductively Coupled Endoscope Robot.

Science.gov (United States)

Ke, Quan; Luo, Weijie; Yan, Guozheng; Yang, Kai

2016-04-01

A wireless power transfer system based on the weakly inductive coupling makes it possible to provide the endoscope microrobot (EMR) with infinite power. To facilitate the patients' inspection with the EMR system, the diameter of the transmitting coil is enlarged to 69 cm. Due to the large transmitting range, a high quality factor of the Litz-wire transmitting coil is a necessity to ensure the intensity of magnetic field generated efficiently. Thus, this paper builds an analytical model of the transmitting coil, and then, optimizes the parameters of the coil by enlarging the quality factor. The lumped model of the transmitting coil includes three parameters: ac resistance, self-inductance, and stray capacitance. Based on the exact two-dimension solution, the accurate analytical expression of ac resistance is derived. Several transmitting coils of different specifications are utilized to verify this analytical expression, being in good agreements with the measured results except the coils with a large number of strands. Then, the quality factor of transmitting coils can be well predicted with the available analytical expressions of self- inductance and stray capacitance. Owing to the exact estimation of quality factor, the appropriate coil turns of the transmitting coil is set to 18-40 within the restrictions of transmitting circuit and human tissue issues. To supply enough energy for the next generation of the EMR equipped with a Ø9.5×10.1 mm receiving coil, the coil turns of the transmitting coil is optimally set to 28, which can transfer a maximum power of 750 mW with the remarkable delivering efficiency of 3.55%.

Large superconducting coil fabrication development

International Nuclear Information System (INIS)

Brown, R.L.; Allred, E.L.; Anderson, W.C.; Burn, P.B.; Deaderick, R.I.; Henderson, G.M.; Marguerat, E.F.

1975-01-01

Toroidal fields for some fusion devices will be produced by an array of large superconducting coils. Their size, space limitation, and field requirements dictate that they be high performance coils. Once installed, accessibility for maintenance and repairs is severely restricted; therefore, good reliability is an obvious necessity. Sufficient coil fabrication will be undertaken to develop and test methods that are reliable, fast, and economical. Industrial participation will be encouraged from the outset to insure smooth transition from development phases to production phases. Initially, practice equipment for three meter bore circular coils will be developed. Oval shape coil forms will be included in the practice facility later. Equipment that is more automated will be developed with the expectation of winding faster and obtaining good coil quality. Alternate types of coil construction, methods of winding and insulating, will be investigated. Handling and assembly problems will be studied. All technology developed must be feasible for scaling up when much larger coils are needed. Experimental power reactors may need coils having six meter or larger bores

Multicoil2: predicting coiled coils and their oligomerization states from sequence in the twilight zone.

Directory of Open Access Journals (Sweden)

Jason Trigg

Full Text Available The alpha-helical coiled coil can adopt a variety of topologies, among the most common of which are parallel and antiparallel dimers and trimers. We present Multicoil2, an algorithm that predicts both the location and oligomerization state (two versus three helices of coiled coils in protein sequences. Multicoil2 combines the pairwise correlations of the previous Multicoil method with the flexibility of Hidden Markov Models (HMMs in a Markov Random Field (MRF. The resulting algorithm integrates sequence features, including pairwise interactions, through multinomial logistic regression to devise an optimized scoring function for distinguishing dimer, trimer and non-coiled-coil oligomerization states; this scoring function is used to produce Markov Random Field potentials that incorporate pairwise correlations localized in sequence. Multicoil2 significantly improves both coiled-coil detection and dimer versus trimer state prediction over the original Multicoil algorithm retrained on a newly-constructed database of coiled-coil sequences. The new database, comprised of 2,105 sequences containing 124,088 residues, includes reliable structural annotations based on experimental data in the literature. Notably, the enhanced performance of Multicoil2 is evident when tested in stringent leave-family-out cross-validation on the new database, reflecting expected performance on challenging new prediction targets that have minimal sequence similarity to known coiled-coil families. The Multicoil2 program and training database are available for download from http://multicoil2.csail.mit.edu.

Coil measurement data acquisition and curing press control system for SSC dipole magnet coils

International Nuclear Information System (INIS)

Dickey, C.E.

1989-03-01

A coil matching program, similar in theory to the methods used to match Tevatron coils, is being developed at Fermilab. Modulus of elasticity and absolute coil size will be determined at 18-inch intervals along the coils while in the coil curing press immediately following the curing process. A data acquisition system is under construction to automatically acquire and manage the large quantities of data that result. Data files will be transferred to Fermilab's VAX Cluster for long-term storage and actual coil matching. The data acquisition system will also provide the control algorithm for the curing press hydraulic system. A description of the SSC Curing Press Data Acquisition and Controls System will be reported. 20 figs

Adaptation of the Electra Radio to Support Multiple Receive Channels

Science.gov (United States)

Satorius, Edgar H.; Shah, Biren N.; Bruvold, Kristoffer N.; Bell, David J.

2011-01-01

Proposed future Mars missions plan communication between multiple assets (rovers). This paper presents the results of a study carried out to assess the potential adaptation of the Electra radio to a multi-channel transceiver. The basic concept is a Frequency Division multiplexing (FDM) communications scheme wherein different receiver architectures are examined. Options considered include: (1) multiple IF slices, A/D and FPGAs each programmed with an Electra baseband modem; (2) common IF but multiple A/Ds and FPGAs and (3) common IF, single A/D and single or multiple FPGAs programmed to accommodate the FDM signals. These options represent the usual tradeoff between analog and digital complexity. Given the space application, a common IF is preferable; however, multiple users present dynamic range challenges (e.g., near-far constraints) that would favor multiple IF slices (Option 1). Vice versa, with a common IF and multiple A/Ds (Option 2), individual AGC control of the A/Ds would be an important consideration. Option 3 would require a common AGC control strategy and would entail multiple digital down conversion paths within the FPGA. In this paper, both FDM parameters as well as the different Electra design options will be examined. In particular, signal channel spacing as a function of user data rates and transmit powers will be evaluated. In addition, tradeoffs between the different Electra design options will be presented with the ultimate goal of defining an augmented Electra radio architecture for potential future missions.

Open coil traction system.

Science.gov (United States)

Vibhute, Pavankumar Janardan

2012-01-01

Sliding mechanics have become a popular method for space closure, with the development of preadjusted edgewise appliances. Furthermore, various space closing auxiliaries have been developed and extensively evaluated for their clinical efficiency. Their effectiveness is enhanced with optimum force magnitude and low load deflection rate/force decay. With the advent of nickel-titanium (Ni-Ti) springs in orthodontics, load deflection rates have been markedly reduced. To use Ni-Ti springs, clinicians have to depend upon prefabricated closed coil springs. The open coil traction system, or open coil retraction spring, is developed utilizing Ni-Ti open coil springs for orthodontic space closure. This article describes the fabrication and clinical application of the open coil traction system, which has a number of advantages. It sustains a low load deflection rate with optimum force magnitude, and its design is adjustable for a desired length and force level. It is fail-safe for both activation and deactivation (ie, it cannot be overactivated, and the decompression limit of the open coil is controlled by the operator). The open coil traction system can be offset from the mucosa to help reduce soft tissue impingement.

Plasmodium vivax antigen discovery based on alpha-helical coiled coil protein motif.

Directory of Open Access Journals (Sweden)

Nora Céspedes

Full Text Available Protein α-helical coiled coil structures that elicit antibody responses, which block critical functions of medically important microorganisms, represent a means for vaccine development. By using bioinformatics algorithms, a total of 50 antigens with α-helical coiled coil motifs orthologous to Plasmodium falciparum were identified in the P. vivax genome. The peptides identified in silico were chemically synthesized; circular dichroism studies indicated partial or high α-helical content. Antigenicity was evaluated using human sera samples from malaria-endemic areas of Colombia and Papua New Guinea. Eight of these fragments were selected and used to assess immunogenicity in BALB/c mice. ELISA assays indicated strong reactivity of serum samples from individuals residing in malaria-endemic regions and sera of immunized mice, with the α-helical coiled coil structures. In addition, ex vivo production of IFN-γ by murine mononuclear cells confirmed the immunogenicity of these structures and the presence of T-cell epitopes in the peptide sequences. Moreover, sera of mice immunized with four of the eight antigens recognized native proteins on blood-stage P. vivax parasites, and antigenic cross-reactivity with three of the peptides was observed when reacted with both the P. falciparum orthologous fragments and whole parasites. Results here point to the α-helical coiled coil peptides as possible P. vivax malaria vaccine candidates as were observed for P. falciparum. Fragments selected here warrant further study in humans and non-human primate models to assess their protective efficacy as single components or assembled as hybrid linear epitopes.

Split coil made of (RE)BCO pancake coils for IC(B) anisotropy measurements of superconductors

International Nuclear Information System (INIS)

Frolek, L; Pardo, E; Gömöry, F; Šouc, J; Pitel, J

2014-01-01

Measurement of the I c (B) anisotropy is standard characterization of superconducting tapes, wires or cables. This contribution presents a split coil consisting on two superconducting pancake coils in order to generate the magnetic field necessary for this kind of measurement. Both coils were made using (RE)BCO – based second generation (2G) coated conductor tape with cross section 0.1 mm × 12 mm. The individual turns of the tape were insulated by a fiberglass tape without impregnation. These coils have identical inner and outer diameter and number of turns. Their inner and outer diameters are 50 mm and 80 mm, respectively, and they have 62 turns. The length of conductor in each coil is approximately 13 m. The distance between both pancake coils is 22 mm. Individual coils and the complete split coil were characterized in liquid nitrogen bath. Their parameters, like the critical currents, E(I) characteristics and magnetic field of complete split coil, were measured and interpreted. The split coil can be used up to magnetic fields of 210 mT. The length between the potential taps on the sample can be up to 20 mm, while the magnetic field decrease is lower than 1% on this length.

Unraveling double stranded alpha-helical coiled coils: an x-ray diffraction study on hard alpha-keratin fibers.

Science.gov (United States)

Kreplak, L; Doucet, J; Briki, F

2001-04-15

Transformations of proteins secondary and tertiary structures are generally studied in globular proteins in solution. In fibrous proteins, such as hard alpha-keratin, that contain long and well-defined double stranded alpha-helical coiled coil domains, such study can be directly done on the native fibrous tissue. In order to assess the structural behavior of the coiled coil domains under an axial mechanical stress, wide angle x-ray scattering and small angle x-ray scattering experiments have been carried out on stretched horse hair fibers at relative humidity around 30%. Our observations of the three major axial spacings as a function of the applied macroscopic strain have shown two rates. Up to 4% macroscopic strain the coiled coils were slightly distorted but retained their overall conformation. Above 4% the proportion of coiled coil domains progressively decreased. The main and new result of our study is the observation of the transition from alpha-helical coiled coils to disordered chains instead of the alpha-helical coiled coil to beta-sheet transition that occurs in wet fibers.

The coiled coil motif in polymer drug delivery systems

Czech Academy of Sciences Publication Activity Database

Pechar, Michal; Pola, Robert

2013-01-01

Roč. 31, č. 1 (2013), s. 90-96 ISSN 0734-9750 R&D Projects: GA ČR GA203/08/0543; GA MŠk 1M0505 Institutional research plan: CEZ:AV0Z40500505 Keywords : coiled coil * hydrophilic polymer * recombinant protein Subject RIV: CD - Macromolecular Chemistry Impact factor: 8.905, year: 2013

Coil protection calculator for TFTR

International Nuclear Information System (INIS)

Marsala, R.J.; Woolley, R.D.

1987-01-01

A new coil protection calculator (CPC) is presented in this paper. It is now being developed for TFTR's magnetic field coils will replace the existing coil fault detector. The existing fault detector sacrifices TFTR operating capability for simplicity. The new CPC will permit operation up to the actual coil limits by accurately and continuously computing coil parameters in real-time. The improvement will allow TFTR to operate with higher plasma currents and will permit the optimization of pulse repetition rates

Performance evaluation of matrix gradient coils.

Science.gov (United States)

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.

Quench detector for large pulsed coils and quench analysis for the LASL/Westinghouse 20 MJ coil

International Nuclear Information System (INIS)

Hennessy, M.J.; Heintz, A.W.; Eckels, P.W.

1981-01-01

A detection scheme has been devised for use in the test of the 20 Mj Induction Heating Coil. This scheme allows the sensing of plus or minus voltages less than 320 mv resistive in magnitude in coils which will have inductive voltage components as high as /plus or minus/2.5 kv. The network which achieves this sensitivity is stable to less than 12.8 ppm. This method adopted involves the bucking out of the inductive voltage with two secondary co-wound flux sensing coils tapped at locations adjacent to voltage taps in the main superconducting coil. The detection scheme is recommended if large ripple or control voltages exist subsequent to the coil pulse. The most severe event which might quench the coil and/or damage the winding is exposure of the coil to gaseous cooling through lack of proper liquid level control. The detection scheme will protect the coil against this and other abnormal conditions that could damage the coil

A harmonic coil measurement system based on a dynamic signal acquisition device

Energy Technology Data Exchange (ETDEWEB)

Zhou, J.X., E-mail: zhoujx@ihep.ac.c [Institute of High Energy Physics, P.O. Box 918-9, Beijing 100049 (China); Li, L.; Yin, B.G.; Deng, C.D.; Kang, W.; Chen, Y.; Zhang, Z.; Fu, S.N. [Institute of High Energy Physics, P.O. Box 918-9, Beijing 100049 (China)

2010-12-21

A new harmonic coil measurement system based on a dynamic signal acquisition device has been successfully developed to check the field quality of the quadrupole magnet for the CSNS/RCS, which operates at the 25 Hz excitation cycle with a DC bias. It was designed to acquire multiple channels of data with a wide dynamic range of input signals, which are typically generated by a harmonic coil and an encoder. A dedicated algorithm was developed in LabView code to identify over specified intervals, synchronized to the coil's rotation in the magnetic field. Through full integration of hardware and software, the traditional device (PDI 5025) is replaced successfully. This paper summarizes the characteristics of the system and presents the results of DC measurements.

Supporting device for Toroidal coils

International Nuclear Information System (INIS)

Araki, Takao.

1985-01-01

Purpose: To reduce the response of a toroidal coil supporting device upon earthquakes and improve the earthquake proofness in a tokamak type thermonuclear device. Constitution: Structural materials having large longitudinal modulus and enduring great stresses, for example, stainless steels are used as the toroidal coil supporting legs and heat insulating structural materials are embedded in a nuclear reactor base mats below the supporting legs. Furthermore, heat insulating concretes are spiked around the heat insulating structural materials to prevent the intrusion of heat to the toroidal coils. The toroidal coils are kept at cryogenic state and superconductive state for the conductors. In this way, the period of proper vibrations of the toroidal coils and the toroidal coil supporting structures can be shortened thereby decreasing the seismic response. Furthermore, since the strength of the supporting legs is increased, the earthquake proofness of the coils can be improved. (Kamimura, M.)

Fifty years of coiled-coils and alpha-helical bundles: a close relationship between sequence and structure.

Science.gov (United States)

Parry, David A D; Fraser, R D Bruce; Squire, John M

2008-09-01

alpha-Helical coiled coils are remarkable for the diversity of related conformations that they adopt in both fibrous and globular proteins, and for the range of functions that they exhibit. The coiled coils are based on a heptad (7-residue), hendecad (11-residue) or a related quasi-repeat of apolar residues in the sequences of the alpha-helical regions involved. Most of these, however, display one or more sequence discontinuities known as stutters or stammers. The resulting coiled coils vary in length, in the number of chains participating, in the relative polarity of the contributing alpha-helical regions (parallel or antiparallel), and in the pitch length and handedness of the supercoil (left- or right-handed). Functionally, the concept that a coiled coil can act only as a static rod is no longer valid, and the range of roles that these structures have now been shown to exhibit has expanded rapidly in recent years. An important development has been the recognition that the delightful simplicity that exists between sequence and structure, and between structure and function, allows coiled coils with specialized features to be designed de novo.

Versatile fill coils: initial experience as framing coils for oblong aneurysms. A technical case report.

Science.gov (United States)

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

2014-01-01

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

Commercial applications for COIL

Science.gov (United States)

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.

Control of intravascular catheters using an array of active steering coils.

Science.gov (United States)

Gudino, N; Heilman, J A; Derakhshan, J J; Sunshine, J L; Duerk, J L; Griswold, M A

2011-07-01

To extend the concept of deflecting the tip of a catheter with the magnetic force created in an MRI system through the use of an array of independently controllable steering coils located in the catheter tip, and to present methods for visualization of the catheter and/or surrounding areas while the catheter is deflected. An array of steering coils made of 42-gauge wire was built over a 2.5 Fr (0.83 mm) fiber braided microcatheter. Two of the coils were 70 turn axial coils separated by 1 cm, and the third was a 15-turn square side coil that was 2 x 4 mm2. Each coil was driven independently by a pulse width modulation (PWM) current source controlled by a microprocessor that received commands from a MATLAB routine that dynamically set current amplitude and direction for each coil. The catheter was immersed in a water phantom containing 1% Gd-DTPA that was placed at the isocenter of a 1.5 T MRI scanner. Deflections of the catheter tip were measured from image-based data obtained with a real-time radio frequency (RF) spoiled gradient echo sequence (GRE). The small local magnetic fields generated by the steering coils were exploited to generate a hyperintense signal at the catheter tip by using a modified GRE sequence that did not include slice-select rewinding gradients. Imaging and excitation modes were implemented by synchronizing the excitation of the steering coil array with the scanner by ensuring that no current was driven through the coils during the data acquisition window; this allowed visualization of the surrounding tissue while not affecting the desired catheter position. Deflections as large as 2.5 cm were measured when exciting the steering coils sequentially with a 100 mA maximum current per coil. When exciting a single axial coil, the deflection was half this value with 30% higher current. A hyperintense catheter tip useful for catheter tracking was obtained by imaging with the modified GRE sequence. Clear visualization of the areas surrounding the

Tiny intracranial aneurysms: Endovascular treatment by coil embolisation or sole stent deployment

International Nuclear Information System (INIS)

Lu Jun; Liu Jiachun; Wang Lijun; Qi Peng; Wang Daming

2012-01-01

Purpose: Tiny intracranial aneurysms pose a significant therapeutic challenge for interventional neuroradiologists. The authors report their preliminary results of endovascular treatment of these aneurysms. Methods: Between January 2002 and December 2009, 52 tiny intracranial aneurysms (defined as ≤3 mm in maximum diameter) in 46 patients (22 men; mean age, 57.9 years) were treated by endosaccular coil embolisation or sole stent deployment in the parent artery. Of 52 aneurysms, 29 had ruptured and 23 remained unruptured. The initial angiographic results, procedural complications, and clinical outcomes were assessed at discharge. Imaging follow-up was performed with cerebral angiography. Results: One aneurysm coiling procedure failed because of unsuccessful micro-catheterization. Forty-three aneurysms were successfully coil embolized, of which complete occlusion was obtained in 14, subtotal occlusion in 18 and incomplete occlusion in 11. The other 8 aneurysms were treated by sole stent deployment in the parent artery. Procedural complications (2 intraprocedural ruptures and 3 thromboembolic events) occurred in 5 (9.6%) of 52 aneurysms, resulting in permanent morbidity in only 1 (2.2%, 1/46) patient. No rebleeding occurred during clinical follow-up (mean duration, 46.7 months). Of the 16 coiled aneurysms that receiving repetitive angiography, 6 initially completely and 3 subtotally occluded aneurysms remained unchanged, 4 initially subtotally and 3 incompletely occluded aneurysms progressed to total occlusion. Five sole stent deployed aneurysms received angiographic follow-up (mean duration, 10.0 months), of which 3 remained unchanged, 1 became smaller and 1 progressed to total occlusion. Conclusion: Endovascular treatment of tiny intracranial aneurysms is technical feasible and relatively safe. Coil embolisation seems to be effective in preventing early recanalisation, whereas sole stenting technique needs further investigation to determine its effectiveness.

The IEA Large Coil Task

International Nuclear Information System (INIS)

Beard, D.S.; Klose, W.; Shimamoto, S.; Vecsey, G.

1988-01-01

A multinational program of cooperative research, development, demonstrations, and exchanges of information on superconducting magnets for fusion was initiated in 1977 under an IEA agreement. The first major step in the development of TF magnets was called the Large Coil Task. Participants in LCT were the U.S. DOE, EURATOM, JAERI, and the Departement Federal de l'Interieur of Switzerland. The goals of LCT were to obtain experimental data, to demonstrate reliable operation of large superconducting coils, and to prove design principles and fabrication techniques being considered for the toroidal magnets of thermonuclear reactors. These goals were to be accomplished through coordinated but largely independent design, development, and construction of six test coils, followed by collaborative testing in a compact toroidal test array at fields of 8 T and higher. Under the terms of the IEA Agreement, the United States built and operated the test facility at Oak Ridge and provided three test coils. The other participants provided one coil each. Information on design and manufacturing and all test data were shared by all. The LCT team of each participant included a government laboratory and industrial partners or contractors. The last coil was completed in 1985, and the test assembly was completed in October of that year. Over the next 23 months, the six-coil array was cooled down and extensive testing was performed. Results were gratifying, as tests achieved design-point performance and well beyond. (Each coil reached a peak field of 9 T.) Experiments elucidated coil behavior, delineated limits of operability, and demonstrated coil safety. (orig./KP)

The heterotrimeric laminin coiled-coil domain exerts anti-adhesive effects and induces a pro-invasive phenotype.

Directory of Open Access Journals (Sweden)

Patricia Santos-Valle

Full Text Available Laminins are large heterotrimeric cross-shaped extracellular matrix glycoproteins with terminal globular domains and a coiled-coil region through which the three chains are assembled and covalently linked. Laminins are key components of basement membranes, and they serve as attachment sites for cell adhesion, migration and proliferation. In this work, we produced a recombinant fragment comprising the entire laminin coiled-coil of the α1-, β1-, and γ1-chains that assemble into a stable heterotrimeric coiled-coil structure independently of the rest of the molecule. This domain was biologically active and not only failed to serve as a substrate for cell attachment, spreading and focal adhesion formation but also inhibited cell adhesion to laminin when added to cells in a soluble form at the time of seeding. Furthermore, gene array expression profiling in cells cultured in the presence of the laminin coiled-coil domain revealed up-regulation of genes involved in cell motility and invasion. These findings were confirmed by real-time quantitative PCR and zymography assays. In conclusion, this study shows for the first time that the laminin coiled-coil domain displays anti-adhesive functions and has potential implications for cell migration during matrix remodeling.

Equilibrium field coil concepts for INTOR

International Nuclear Information System (INIS)

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

Dielectric properties of 3D-printed materials for anatomy specific 3D-printed MRI coils

Science.gov (United States)

Behzadnezhad, Bahareh; Collick, Bruce D.; Behdad, Nader; McMillan, Alan B.

2018-04-01

Additive manufacturing provides a low-cost and rapid means to translate 3D designs into the construction of a prototype. For MRI, this type of manufacturing can be used to construct various components including the structure of RF coils. In this paper, we characterize the material properties (dielectric constant and loss tangent) of several common 3D-printed polymers in the MRI frequency range of 63-300 MHz (for MRI magnetic field strengths of 1.5-7 T), and utilize these material properties in full-wave electromagnetic simulations to design and construct a very low-cost subject/anatomy-specific 3D-printed receive-only RF coil that fits close to the body. We show that the anatomy-specific coil exhibits higher signal-to-noise ratio compared to a conventional flat surface coil.

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

Science.gov (United States)

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.

Multiple Access Interference Reduction Using Received Response Code Sequence for DS-CDMA UWB System

Science.gov (United States)

Toh, Keat Beng; Tachikawa, Shin'ichi

This paper proposes a combination of novel Received Response (RR) sequence at the transmitter and a Matched Filter-RAKE (MF-RAKE) combining scheme receiver system for the Direct Sequence-Code Division Multiple Access Ultra Wideband (DS-CDMA UWB) multipath channel model. This paper also demonstrates the effectiveness of the RR sequence in Multiple Access Interference (MAI) reduction for the DS-CDMA UWB system. It suggests that by using conventional binary code sequence such as the M sequence or the Gold sequence, there is a possibility of generating extra MAI in the UWB system. Therefore, it is quite difficult to collect the energy efficiently although the RAKE reception method is applied at the receiver. The main purpose of the proposed system is to overcome the performance degradation for UWB transmission due to the occurrence of MAI during multiple accessing in the DS-CDMA UWB system. The proposed system improves the system performance by improving the RAKE reception performance using the RR sequence which can reduce the MAI effect significantly. Simulation results verify that significant improvement can be obtained by the proposed system in the UWB multipath channel models.

Design of shielded encircling send-receive type pulsed eddy current probe using numerical analysis method

Energy Technology Data Exchange (ETDEWEB)

Shin, Young Kil [Dept. of Electircal Engineeirng, Kunsan National University, Kunsan (Korea, Republic of)

2013-12-15

An encircling send-receive type pulsed eddy current (PEC) probe is designed for use in aluminum tube inspection. When bare receive coils located away from the exciter were used, the peak time of the signal did not change although the distance from the exciter increased. This is because the magnetic flux from the exciter coil directly affects the receive coil signal. Therefore, in this work, both the exciter and the sensor coils were shielded in order to reduce the influence of direct flux from the exciter coil. Numerical simulation with the designed shielded encircling PEC probe showed the corresponding increase of the peak time as the sensor distance increased. Ferrite and carbon steel shields were compared and results of the ferrite shielding showed a slightly stronger peak value and a quicker peak time than those of the carbon steel shielding. Simulation results showed that the peak value increased as the defect size (such as depth and length) increased regardless of the sensor location. To decide a proper sensor location, the sensitivity of the peak value to defect size variation was investigated and found that the normalized peak value was more sensitive to defect size variation when the sensor was located closer to the exciter.

Bow-shaped toroidal field coils

International Nuclear Information System (INIS)

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

Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery.

Science.gov (United States)

Chittiboina, Prashant; Talagala, S Lalith; Merkle, Hellmut; Sarlls, Joelle E; Montgomery, Blake K; Piazza, Martin G; Scott, Gretchen; Ray-Chaudhury, Abhik; Lonser, Russell R; Oldfield, Edward H; Koretsky, Alan P; Butman, John A

2016-12-01

OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing's disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra-high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm 3 and 0.15 × 0.15 × 0.30 mm 3 , respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p anterior pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented resolution. Clinical use of this ESC may allow for MR imaging detection of previously occult

Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery

Science.gov (United States)

Chittiboina, Prashant; Talagala, S. Lalith; Merkle, Hellmut; Sarlls, Joelle E.; Montgomery, Blake K.; Piazza, Martin G.; Scott, Gretchen; Ray-Chaudhury, Abhik; Lonser, Russell R.; Oldfield, Edward H.; Koretsky, Alan P.; Butman, John A.

2016-01-01

OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing’s disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra–high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm3 and 0.15 × 0.15 × 0.30 mm3, respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented resolution. Clinical use of this ESC may allow for MR imaging detection of previously occult pituitary

PDX toroidal field coils stress analysis

International Nuclear Information System (INIS)

Nikodem, Z.D.; Smith, R.A.

1975-01-01

A method used in the stress analysis of the PDX toroidal field coil is developed. A multilayer coil design of arbitrary dimensions in the shape of either a circle or an oval is considered. The analytical model of the coil and the supporting coil case with connections to the main support structure is analyzed using the finite element technique. The three dimensional magnetic fields and the non-uniform body forces which are a loading condition on a coil due to toroidal and poloidal fields are calculated. The method of analysis permits rapid and economic evaluations of design changes in coil geometry as well as in coil support structures. Some results pertinent to the design evolution and their comparison are discussed. The results of the detailed stress analysis of the final coil design due to toroidal field, poloidal field and temperature loads are presented

Transmit-Only/Receive-Only Radiofrequency System for Hyperpolarized 13C MRS Cardiac Metabolism Studies in Pigs

DEFF Research Database (Denmark)

Giovannetti, G.; Frijia, F.; Hartwig, V.

2013-01-01

Hyperpolarized 13C magnetic resonance spectroscopy in pig models enables metabolic activity mapping, providing a powerful tool for the study of the heart physiology, but requires the development of dedicated radiofrequency coils, capable of providing large field of view with high signal......-to-noise ratio (SNR) data. This work describes the simulations and the tests of a transmit-only (TX) volume coil/receive-only (RX) surface coil both designed for hyperpolarized studies of pig heart with a clinical 3T scanner. The coil characterization is performed by developing an SNR model for coil performance...

Study on the performance improvement of the high temperature superconducting coil with several separated coils at the edges

International Nuclear Information System (INIS)

Ishiguri, S.; Oka, T.; Fukui, S.; Ogawa, J.; Sato, T.

2008-01-01

In designing high temperature superconducting (HTS) coils, it is important to secure large magnetic fields and stored energy using shorter tape length. Thus, it is necessary to improve the transport current performance of the coils. The critical current and n-value of an HTS tape depend on magnetic fields and flux angles under constant temperature. Considering these dependencies, we established a model to analyze coil critical current. This model clarifies that relatively large electric fields are generated at the coil edges. This adversely affects the transport current performance. In this study, the coil edge is separated into several coils, keeping the total tape length constant. This increases the coil critical current, stored energy, central magnetic field, and also the coil volume, which contains vacancies created by the separation. To estimate coil performance, we calculated the stored energy density, whose denominator is the increased coil volume. This stored energy density reaches its maximum value when the number of the separated coils is eight. At this optimum separation, the central magnetic field increases by 13%, and the stored energy improves by 43%, compared to a rectangular coil wound with the same tape length

Design and manufacturing status of trim coils for the Wendelstein 7-X stellarator experiment

Energy Technology Data Exchange (ETDEWEB)

Riße, K., E-mail: konrad.risse@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Rummel, Th.; Freundt, S.; Dudek, A.; Renard, S.; Bykov, V.; Köppen, M. [Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Langish, S.; Neilson, G.H.; Brown, Th.; Chrzanowski, J.; Mardenfeld, M.; Malinowski, F.; Khodak, A.; Zhao, X. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Eksaa, G. [Everson Tesla Inc., Nazareth, PA (United States)

2013-10-15

Highlights: ► The trim coil system will fine tune the main magnetic field during plasma operation by reducing the magnetic field errors. ► The coil design and operational parameters are fixed, the manufacturing is running. ► The coils are equipped with temperature sensors and a voltage tap system to monitor the coil temperature. ► The max. operational deflection is in the order of 4.5 mm; the max. shearing stress across bond planes is of order 16 MPa. ► Special clamps equipped with elastomeric pads allow fixing the coils on the outer cryostat wall. -- Abstract: The stellarator fusion experiment Wendelstein 7-X (W7-X) is currently under construction at the Max-Planck-Institut für Plasmaphysik in Greifswald, Germany. The main magnetic field will be provided by a superconducting magnet system which generates a fivefold toroidal periodic magnetic field. However, unavoidable tolerances can result in small deviations of the magnetic field which disturb the toroidal periodicity. In order to have a tool to influence these field errors five additional normal conducting trim coils were designed to allow fine tuning of the main magnetic field during plasma operation. In the frame of an international cooperation the trim coils will be contributed by the US partners. Princeton Plasma Physics Laboratory has accomplished several tasks to develop the final design ready for manufacturing e.g. detailed manufacturing design for the winding and for the coil connection area. The design work was accompanied by a detailed analysis of resulting forces and moments to prove the design. The manufacturing of the coils is running at Everson Tesla Inc; the first two coils were received at IPP.

An Autonomous Coil Alignment System for the Dynamic Wireless Charging of Electric Vehicles to Minimize Lateral Misalignment

Directory of Open Access Journals (Sweden)

Karam Hwang

2017-03-01

Full Text Available This paper proposes an autonomous coil alignment system (ACAS for electric vehicles (EVs with dynamic wireless charging (DWC to mitigate the reduction in received power caused by lateral misalignment between the source and load coils. The key component of the ACAS is a novel sensor coil design, which can detect the load coil’s left or right position relative to the source coil by observing the change in voltage phase. This allows the lateral misalignment to be estimated through the wireless power transfer (WPT system alone, which is a novel tracking method for vehicular applications. Once misalignment is detected, the vehicle’s lateral position is self-adjusted by an autonomous steering function. The feasibility of the overall operation of the ACAS was verified through simulation and experiments. In addition, an analysis based on experimental results was conducted, demonstrating that 26% more energy can be transferred during DWC with the ACAS, just by keeping the vehicle’s load coil aligned with the source coil.

Liquid rope coiling

NARCIS (Netherlands)

Ribe, N.M.; Habibi, M.; Bonn, D.

2012-01-01

A thin stream or rope of viscous fluid falling from a sufficient height onto a surface forms a steadily rotating helical coil. Tabletop laboratory experiments in combination with a numerical model for slender liquid ropes reveal that finite-amplitude coiling can occur in four distinct regimes

Performance of external and internal coil configurations for prostate investigations at 7 Tesla

Science.gov (United States)

Metzger, Gregory J.; van de Moortele, Pierre-Francois; Akgun, Can; Snyder, Carl J.; Moeller, Steen; Strupp, John; Andersen, Peter; Shrivastava, Devashish; Vaughan, Tommy; Ugurbil, Kamil; Adriany, Gregor

2010-01-01

Three different coil configurations were evaluated through simulation and experimentally to determine safe operating limits and evaluate subject size dependent performance for prostate imaging at 7 Tesla. The coils included a transceiver endorectal coil (trERC), a 16 channel transceiver external surface array (trESA) and a trESA combined with a receive-only ERC (trESA+roERC). While the transmit B1 (B1+) homogeneity was far superior for the trESA, the maximum achievable B1+ is subject size dependent and limited by transmit chain losses and amplifier performance. For the trERC, limitations in transmit homogeneity greatly compromised image quality and limited coverage of the prostate. Despite these challenges, the high peak B1+ close to the trERC and subject size independent performance provides potential advantages especially for spectroscopic localization where high bandwidth RF pulses are required. On the receive side, the combined trESA+roERC provided the highest SNR and improved homogeneity over the trERC resulting in better visualization of the prostate and surrounding anatomy. In addition, the parallel imaging performance of the trESA+roERC holds strong promise for diffusion weighted imaging and dynamic contrast enhanced MRI. PMID:20740657

Cooling and dehumidifying coils

International Nuclear Information System (INIS)

Murthy, M.V.K.

1988-01-01

The operating features of cooling and dehumidifying coils and their constructional details are discussed. The heat transfer relations as applicable to the boiling refrigerant and a single phase fluid are presented. Methods of accounting for the effect of moisture condensation on the air side heat transfer coefficient and the fin effectiveness are explained. The logic flow necessary to analyze direct expansion coils and chilled water coils is discussed

Comparison of the association of sac growth and coil compaction with recurrence in coil embolized cerebral aneurysms.

Directory of Open Access Journals (Sweden)

Anna L Hoppe

Full Text Available In recurrent cerebral aneurysms treated by coil embolization, coil compaction is regarded as the presumptive mechanism. We test the hypothesis that aneurysm growth is the primary recurrence mechanism. We also test the hypothesis that the coil mass will translate a measurable extent when recurrence occurs.An objective, quantitative image analysis protocol was developed to determine the volumes of aneurysms and coil masses during initial and follow-up visits from 3D rotational angiograms. The population consisted of 15 recurrence and 12 non-recurrence control aneurysms initially completely coiled at a single center. An investigator sensitivity study was performed to assess the objectivity of the methods. Paired Wilcoxon tests (p<0.05, one-tailed were performed to assess for aneurysm and coil growth. The translation of the coil mass center at follow-up was computed. A Mann Whitney U-Test (p<0.05, one-tailed was used to compare translation of coil mass centers between recurrence and control subjects.Image analysis protocol was found to be insensitive to the investigator. Aneurysm growth was evident in the recurrence cohort (p=0.003 but not the control (p=0.136. There was no evidence of coil compaction in either the recurrence or control cohorts (recurrence: p=0.339; control: p=0.429. The translation of the coil mass centers was found to be significantly larger in the recurrence cohort than the control cohort (p=0.047.Aneurysm sac growth, not coil compaction, was the primary mechanism of recurrence following successful coil embolization. The coil mass likely translates to a measurable extent when recurrence occurs and has the potential to serve as a non-angiographic recurrence marker.

A coil test facility for the cryogenic tests of the JT-60SA TF coils

International Nuclear Information System (INIS)

Chantant, M.; Genini, L.; Bayetti, P.; Millet, F.; Wanner, M.; Massaut, V.; Corte, A. Della; Ardelier-Desage, F.; Catherine-Dumont, V.; Dael, A.; Decool, P.; Donati, A.; Duchateau, J.L.; Garibaldi, P.; Girard, S.; Hatchressian, J.C.; Fejoz, P.; Jamotton, P.; Jourdheuil, L.; Juster, F.P.

2011-01-01

In the framework of the Broader Approach Activities, the EU will deliver to Japan the 18 superconducting coils, which constitute the JT-60SA Toroidal field magnet. These 18 coils, manufactured by France and Italy, will be cold tested before shipping to Japan. For this purpose, the European Joint Undertaking for ITER, the Development of Fusion Energy ('Fusion for Energy', F4E) and the European Voluntary Contributors are collaborating to design and set-up a coil test facility (CTF) and to perform the acceptance test of the 18 JT-60SA Toroidal Field (TF) coils. The test facility is designed to test one coil at a time at nominal current and cryogenic temperature. The test of the first coil of each manufacturer includes a quench triggered by increasing the temperature. The project is presently in the detailed design phase.

Measurement of heating coil temperature for e-cigarettes with a “top-coil” clearomizer

Science.gov (United States)

Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A.; Kumagai, Kazukiyo

2018-01-01

Objectives To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a “top-coil” clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. Methods The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3–6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). Results For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such “top-coil” clearomizers. Conclusions This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full

Echocardiographic predictors of coil vs device closure in patients undergoing percutaneous patent ductus arteriosus closure.

Science.gov (United States)

Roushdy, Alaa; Abd El Razek, Yasmeen; Mamdouh Tawfik, Ahmed

2018-01-01

To determine anatomic and hemodynamic echocardiographic predictors for patent ductus arteriosus (PDA) device vs coil closure. Seventy-six patients who were referred for elective transcatheter PDA closure were enrolled in the study. All patients underwent full echocardiogram including measurement of the PDA pulmonary end diameter, color flow width and extent, peak and end-diastolic Doppler gradients across the duct, diastolic flow reversal, left atrial dimensions and volume, left ventricular sphericity index, and volumes. The study group was subdivided into 2 subgroups based on the mode of PDA closure whether by coil (n = 42) or device (n = 34). Using univariate analysis there was a highly significant difference between the 2 groups as regard the pulmonary end diameter measured in both the suprasternal and parasternal short-axis views as well as the color flow width and color flow extent (P closure group had statistically significant higher end-systolic and end-diastolic volumes indexed, left atrial volume, and diastolic flow reversal. Receiver operating characteristic curve analysis showed a pulmonary end diameter cutoff point from the suprasternal view > 2.5 mm and from parasternal short-axis view > 2.61 mm to have the highest balanced sensitivity and specificity to predict the likelihood for device closure (AUC 0.971 and 0.979 respectively). The pulmonary end diameter measured from the suprasternal view was the most independent predictor of device closure. The selection between PDA coil or device closure can be done on the basis of multiple anatomic and hemodynamic echocardiographic variables. © 2017 Wiley Periodicals, Inc.

Design and testing of a coil-unit barrel for helical coil electromagnetic launcher

Science.gov (United States)

Yang, Dong; Liu, Zhenxiang; Shu, Ting; Yang, Lijia; Ouyang, Jianming

2018-01-01

A coil-unit barrel for a helical coil electromagnetic launcher is described. It provides better features of high structural strength and flexible adjustability. It is convenient to replace the damaged coil units and easy to adjust the number of turns in the stator coils due to the modular design. In our experiments, the highest velocity measured for a 4.5-kg projectile is 47.3 m/s and the mechanical reinforcement of the launcher could bear 35 kA peak current. The relationship between the energy conversion efficiency and the inductance gradient of the launcher is also studied. In the region of low inductance gradient, the efficiency is positively correlated with the inductance gradient. However, in the region of high inductance gradient, the inter-turn arc erosion becomes a major problem of limiting the efficiency and velocity of the launcher. This modular barrel allows further studies in the inter-turn arc and the variable inductance gradient helical coil launcher.

Analysing radio-frequency coil arrays in high-field magnetic resonance imaging by the combined field integral equation method

Energy Technology Data Exchange (ETDEWEB)

Wang Shumin; Duyn, Jeff H [Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, 10/B1D728, Bethesda, MD 20892 (United States)

2006-06-21

We present the combined field integral equation (CFIE) method for analysing radio-frequency coil arrays in high-field magnetic resonance imaging (MRI). Three-dimensional models of coils and the human body were used to take into account the electromagnetic coupling. In the method of moments formulation, we applied triangular patches and the Rao-Wilton-Glisson basis functions to model arbitrarily shaped geometries. We first examined a rectangular loop coil to verify the CFIE method and also demonstrate its efficiency and accuracy. We then studied several eight-channel receive-only head coil arrays for 7.0 T SENSE functional MRI. Numerical results show that the signal dropout and the average SNR are two major concerns in SENSE coil array design. A good design should be a balance of these two factors.

Normal-zone detectors for the MFTF-B coils. Revision 1

International Nuclear Information System (INIS)

Owen, E.W.; Shimer, D.W.

1983-01-01

In order to protect a set of inductively coupled superconducting magnets, it is necessary to locate and measure normal zone voltages that are small compared with the mutual and self-induced voltages. The method described in this report uses two sets of voltage measurements to locate and measure one or more normal zones in any number of coupled coils. One set of voltages is the outputs of bridges that balance out the self-induced voltages. The other set of voltages can be the voltages across the coils, although alternatives are possible. The two sets of equations form a single combined set of equations. Each normal zone location or combination of normal zones has a set of these combined equations associated with it. It is demonstrated that the normal zone can be located and the correct set chosen, allowing determination of the size of the normal zone. Only a few operations take place in a working detector: multiplication of a constant, addition, and simple decision-making. In many cases the detector for each coil, although weakly linked to the other detectors, can be considered to be independent. An example of the detector design is given for four coils with realistic parameters. The effect on accuracy of changes in the system parameters is discussed

Time-domain finite-difference/finite-element hybrid simulations of radio frequency coils in magnetic resonance imaging

International Nuclear Information System (INIS)

Wang Shumin; Duyn, Jeff H

2008-01-01

A hybrid method that combines the finite-difference time-domain (FDTD) method and the finite-element time-domain (FETD) method is presented for simulating radio-frequency (RF) coils in magnetic resonance imaging. This method applies a high-fidelity FETD method to RF coils, while the human body is modeled with a low-cost FDTD method. Since the FDTD and the FETD methods are applied simultaneously, the dynamic interaction between RF coils and the human body is fully accounted for. In order to simplify the treatment of the highly irregular FDTD/FETD interface, composite elements are proposed. Two examples are provided to demonstrate the validity and effectiveness of the hybrid method in high-field receive-and-transmit coil design. This approach is also applicable to general bio-electromagnetic simulations

ANL experimental program for pulsed superconducting coils

International Nuclear Information System (INIS)

Wang, S.T.; Kim, S.H.; Praeg, W.F.; Krieger, C.I.

1978-01-01

Argonne National Laboratory (ANL) had recognized the clear advantage of a superconducting ohmic-heating (OH) coil and started in aggressive development program in FY 1977. The main objectives for FY 1977 are to develop cryostable basic cable configurations with reasonably low ac losses, to develop 12 kA cryostable cable, using it to design and build a 1.5 MJ pulsed coil, and to develop a rather inexpensive large fiberglass reinforced helium cryostat for the 1.5 MJ pulsed coil. The principal objective in building the 1.5 MJ ac coil is to demonstrate ac cryostability of a large coil ranging from 2 T/s up to 12 T/s. Another objective in the pulsed coil program is to determine the feasibility of parallel coil operation in order to avoid excessive voltage and current requirements and to minimize the number of turns for the equilibrium field (EF) coils, should the EF coils be connected in parallel with the OH coils. A two-coil section model using the 11 kA cable will be built and tested

ANL experimental program for pulsed superconducting coils

International Nuclear Information System (INIS)

Wang, S.T.; Kim, S.H.; Praeg, W.F.; Krieger, C.I.

1977-01-01

Argonne National Laboratory (ANL) had recognized the clear advantage of a superconducting ohmic-heating (OH) coil and started an aggressive development program in FY 1977. The main objectives for FY 1977 are to develop cryostable basic cable configurations with reasonably low ac losses, to develop 12 kA cryostable cable, using it to design and build a 1.5 MJ pulsed coil, and to develop a rather inexpensive large fiberglass reinforced helium cryostat for the 1.5 MJ pulsed coil. The principal objective in building the 1.5 MJ ac coil is to demonstrate ac cryostability of a large coil ranging from 2 T/s up to 12 T/s. Another objective in the pusled coil program is to determine the feasibility of parallel coil operation in order to avoid excessive voltage and current requirements and to minimize the number of turns for the equilibrium field (EF) coils, should the EF coils be connected in parallel with the OH coils. A two-coil section model using the 11 kA cable will be built and tested

Comparison of surface coil and knee coil for evaluation of the patellar cartilage by MR imaging

International Nuclear Information System (INIS)

Steen, M. van den; Maeseneer, M. de; Hoste, M.; Vanderdood, K.; Ridder, F. de; Osteaux, M.

2003-01-01

Purpose: The aim of this work was to compare the knee coil and the surface coil for the visualisation of the patellar cartilage. Materials and methods: In 28 patients (17 women, 11 men) with an average age of 40 years (range 14-76) with knee pain MR was performed. Transverse images were obtained using a fast spin echo proton density weighted sequence on a Philips Gyroscan Intera 1.5 T clinical system. Transverse images were obtained at the level of the patellar cartilage using both the surface and the knee coil. All images were evaluated by consensus of two radiologists. They evaluated a number of quality criteria on a 4-point scale. Criteria for artefacts were also graded on a 4-point scale. Results: For the visualisation of fluid there was no significant difference between the knee coil and the surface coil (P=0.021). For all other criteria regarding image quality and presence of imaging artefacts there was a significant difference between both coils (P<0.001) with the surface coil obtaining the better result. Conclusion: The use of the surface coil in the visualisation of the patellar cartilage can be recommended at knee MR

Structure of bacteriophage T4 fibritin: a segmented coiled coil and the role of the C-terminal domain.

Science.gov (United States)

Tao, Y; Strelkov, S V; Mesyanzhinov, V V; Rossmann, M G

1997-06-15

Oligomeric coiled-coil motifs are found in numerous protein structures; among them is fibritin, a structural protein of bacteriophage T4, which belongs to a class of chaperones that catalyze a specific phage-assembly process. Fibritin promotes the assembly of the long tail fibers and their subsequent attachment to the tail baseplate; it is also a sensing device that controls the retraction of the long tail fibers in adverse environments and, thus, prevents infection. The structure of fibritin had been predicted from sequence and biochemical analyses to be mainly a triple-helical coiled coil. The determination of its structure at atomic resolution was expected to give insights into the assembly process and biological function of fibritin, and the properties of modified coiled-coil structures in general. The three-dimensional structure of fibritin E, a deletion mutant of wild-type fibritin, was determined to 2.2 A resolution by X-ray crystallography. Three identical subunits of 119 amino acid residues form a trimeric parallel coiled-coil domain and a small globular C-terminal domain about a crystallographic threefold axis. The coiled-coil domain is divided into three segments that are separated by insertion loops. The C-terminal domain, which consists of 30 residues from each subunit, contains a beta-propeller-like structure with a hydrophobic interior. The residues within the C-terminal domain make extensive hydrophobic and some polar intersubunit interactions. This is consistent with the C-terminal domain being important for the correct assembly of fibritin, as shown earlier by mutational studies. Tight interactions between the C-terminal residues of adjacent subunits counteract the latent instability that is suggested by the structural properties of the coiled-coil segments. Trimerization is likely to begin with the formation of the C-terminal domain which subsequently initiates the assembly of the coiled coil. The interplay between the stabilizing effect of the C

High-resolution MR imaging of triangular fibrocartilage complex (TFCC): comparison of microscopy coils and a conventional small surface coil

Energy Technology Data Exchange (ETDEWEB)

Yoshioka, Hiroshi [Department of Radiology, University of Tsukuba, Tsukuba (Japan); Department of Radiology, Brigham and Women' s Hospital, 75 Francis Street, 02115, Boston, MA (United States); Ueno, Teruko; Itai, Yuji [Department of Radiology, University of Tsukuba, Tsukuba (Japan); Tanaka, Toshikazu [Department of Orthopedic Surgery, Tsukuba Kinen Hospital, Tsukuba (Japan); Shindo, Masashi [Tsukuba University Hospital, Tsukuba (Japan)

2003-10-01

To compare MR images of the triangular fibrocartilage complex (TFCC) using microscopy coils with those using a conventional surface coil qualitatively and quantitatively. Proton density-weighted images and T2*-weighted images of the TFCC from ten normal volunteers were obtained with a conventional surface coil (C4 coil; 80 mm in diameter), a 47-mm microscopy surface coil and a 23-mm microscopy surface coil at 1.5 T. Qualitative image analysis of MR images with three coils was performed by two radiologists who assigned one of five numerical scores (0, nonvisualization; 1, poor; 2, average; 3, good; 4, excellent) for five TFCC components, which were disc proper, triangular ligament, meniscus homologue, ulnotriquetral and ulnolunate ligament. Quantitative analysis included the signal-to-noise ratio (S/N) of the disc proper of TFCC, the lunate cartilage, the lunate bone and the contrast-noise-ratio (C/N) between articular cartilage and disc proper or bone marrow were measured. All structures show higher scores qualitatively on MR with microscopy coils than those with a C4 coil, and the difference was significant with the exception of the ulnolunate ligament. MR with microscopy coils showed significantly higher S/N values than those with a conventional surface coil (P<0.05 to P<0.001). T2*-weighted images using microscopy coils showed significantly higher cartilage-disc proper C/N and cartilage-bone marrow C/N (P<0.01 to P<0.001). On proton density-weighted images, the C/N between cartilage and disc proper with two microscopy coils was significantly higher (P<0.01) than that with a conventional coil. High-resolution MR images of the normal wrist using microscopy coils were superior to those using a conventional surface coil qualitatively and quantitatively. High-resolution MR imaging with a microscopy coil would be a promising method to diagnose TFCC lesions. (orig.)

Endovascular rescue method for undesirably stretched coil.

Science.gov (United States)

Cho, Jae Hoon

2014-10-01

Undesirable detachment or stretching of coils within the parent artery during aneurysm embolization can be related with thrombus formation, which can be caused occlusion of parent artery or embolic event(s). To escape from this situation, several rescue methods have been reported. A case with undesirably stretched coil in which another rescue method was used, is presented. When the stretched coil is still located in the coil delivery microcatheter, the stretched coil can be removed safely using a snare and a handmade monorail microcatheter. After a snare is lodged in the handmade monorail microcatheter, the snare is introduced over the coil delivery micorcatheter and located in the distal part of the stretched coil. After then, the handmade monorail microcatheter captures the stretched coil and the snare as one unit. This technique using a handmade monorail microcatheter and a snare can be a good rescue modality for the undesirably stretched coil, still remained within the coil delivery microcatheter.

Operator coil monitoring Acceptance Test Procedure

International Nuclear Information System (INIS)

Erhart, M.F.

1995-01-01

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

Evidence-based pathology: umbilical cord coiling.

Science.gov (United States)

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.

The significant impact of framing coils on long-term outcomes in endovascular coiling for intracranial aneurysms: how to select an appropriate framing coil.

Science.gov (United States)

Ishida, Wataru; Sato, Masayuki; Amano, Tatsuo; Matsumaru, Yuji

2016-09-01

OBJECTIVE The importance of a framing coil (FC)-the first coil inserted into an aneurysm during endovascular coiling, also called a lead coil or a first coil-is recognized, but its impact on long-term outcomes, including recanalization and retreatment, is not well established. The purposes of this study were to test the hypothesis that the FC is a significant factor for aneurysmal recurrence and to provide some insights on appropriate FC selection. METHODS The authors retrospectively reviewed endovascular coiling for 280 unruptured intracranial aneurysms and gathered data on age, sex, aneurysm location, aneurysm morphology, maximal size, neck width, adjunctive techniques, recanalization, retreatment, follow-up periods, total volume packing density (VPD), volume packing density of the FC, and framing coil percentage (FCP; the percentage of FC volume in total coil volume) to clarify the associated factors for aneurysmal recurrence. RESULTS Of 236 aneurysms included in this study, 33 (14.0%) had recanalization, and 18 (7.6%) needed retreatment during a mean follow-up period of 37.7 ± 16.1 months. In multivariate analysis, aneurysm size (odds ratio [OR] = 1.29, p < 0.001), FCP < 32% (OR 3.54, p = 0.009), and VPD < 25% (OR 2.96, p = 0.015) were significantly associated with recanalization, while aneurysm size (OR 1.25, p < 0.001) and FCP < 32% (OR 6.91, p = 0.017) were significant predictors of retreatment. VPD as a continuous value or VPD with any cutoff value could not predict retreatment with statistical significance in multivariate analysis. CONCLUSIONS FCP, which is equal to the FC volume as a percentage of the total coil volume and is unaffected by the morphology of the aneurysm or the measurement error in aneurysm length, width, or height, is a novel predictor of recanalization and retreatment and is more significantly predictive of retreatment than VPD. To select FCs large enough to meet the condition of FCP ≥ 32% is a potential relevant factor for better

The JET divertor coil

International Nuclear Information System (INIS)

Last, J.R.; Froger, C.; Sborchia, C.

1989-01-01

The divertor coil is mounted inside the Jet vacuum vessel and is able to carry 1 MA turns. It is of conventional construction - water cooled copper, epoxy glass insulation -and is contained in a thin stainless steel case. The coil has to be assembled, insulated and encased inside the Jet vacuum vessel. A description of the coil is given, together with technical information (including mechanical effects on the vacuum vessel), an outline of the manufacture process and a time schedule. (author)

Superconducting cyclotron magnet coil short

International Nuclear Information System (INIS)

Mallory, M.L.; Blosser, H.G.; Clark, D.J.; Launer, H.; Lawton, D.; Miller, P.; Resmini, F.

1982-01-01

In February 1981, a short circuit appeared in the superconducting coil of the K500 cyclotron. The short is resistive in character and therefore has no effect on steady state operation of the magnet. The resistance of the short varies, sometimes being below threshold of detection as a heat load on the cooling system and sometimes being significant. The resistance under certain conditions shows approximately cyclic phenomena with time constants in the range of seconds and other approximately cyclic phenomena which correlate with gross operating parameters of the magnet (shifting current from one coil to another at high field and lowering and raising the liquid helium level). A number of diagnostic studies of the short have been made, using 1) an array of flux sensing loops to sense the magnetic effect of the short, 2) voltage comparisons between upper and lower sections of the coil, 3) comparisons of forces in the nine member coil support system and 4) the effect of the short on the thermal charactersitics of the coil. Insulation failure or a metal chip shorting out turns have been explored in some detail but a convincing determination of the exact cause of the short may never be available, (even the extreme step of unwinding the coil having a significant probability that an imperfection with the observed characteristics would pass unnoticed). Analysis of the characteristics of the short indicated that the most serious consequence would be failure of the coils mechanical support system in the event that the magnet was quickly discharged, as in a dump or quench. To deal with this hazard, the support system has been modified by installing solid supports which prevent the coil from moving by an amount sufficient to damage the support system. We have also reexamined the data and calculations used in the original coil design and have made some additional measurements of the properties of the materials (yield strength, friction coefficient, Young's modulus) used in the

Pulse coil concepts for the LCP Facility

International Nuclear Information System (INIS)

Nelson, B.E.; Burn, P.B.

1977-01-01

The pulse coils described in this paper are resistive copper magnets driven by time-varying currents. They are included in the Large Coil Test Facility (LCTF) portion of the Large Coil Program (LCP) to simulate the pulsed field environment of the toroidal coils in a tokamak reactor. Since TNS (a 150 sec, 5MA, igniting tokamak) and the Oak Ridge EPR (Experimental Power Reactor) are representative of the first tokamaks to require the technology developed in LCP, the reference designs for these machines, especially TNS, are used to derive the magnetic criteria for the pulse coils. This criteria includes the magnitude, distribution, and rate of change of pulsed fields in the toroidal coil windings. Three pulse coil concepts are evaluated on the basis of magnetic criteria and factors such as versatility of design, ease of fabrication and cost of operation. The three concepts include (1) a pair of poloidal coils outside the LCTF torus, (2) a single poloidal coil threaded through the torus, and (3) a pair of vertical axis coil windings inside the bore of one or more of the toroidal test coils

LHC bending magnet coil

CERN Multimedia

A short test version of coil of wire used for the LHC dipole magnets. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. Magnet coils are made of copper-clad niobium–titanium cables — each wire in the cable consists of 9’000 niobium–titanium filaments ten times finer than a hair.

A history of detachable coils: 1987-2012.

Science.gov (United States)

Hui, Ferdinand K; Fiorella, David; Masaryk, Thomas J; Rasmussen, Peter A; Dion, Jacques E

2014-03-01

The development of detachable coils is one of the most pivotal developments in neurointervention, providing a tool that could be used to treat a wide variety of hemorrhagic stroke. From the original Guglielmi detachable coil, a number of different coil designs and delivery designs have evolved. This article reviews the history of commercially available detachable coils. A timeline of detachable coils was constructed and coil design philosophies were reviewed. A complete list of commercially available coils is presented in a timeline format. Detachable coil technology continues to evolve. Advances in construction and design have yielded products which may benefit patients in terms of safety, radiation dose reduction and cost of treatment. Continued evolution is expected, irrespective of competing disruptive technologies.

Large Coil Program magnetic system design study

International Nuclear Information System (INIS)

Moses, S.D.; Johnson, N.E.

1977-01-01

The primary objective of the Large Coil Program (LCP) is to demonstrate the reliable operation of large superconducting coils to provide a basis for the design principles, materials, and fabrication techniques proposed for the toroidal magnets for the THE NEXT STEP (TNS) and other future tokamak devices. This paper documents a design study of the Large Coil Test Facility (LCTF) in which the structural response of the Toroidal Field (TF) Coils and the supporting structure was evaluated under simulated reactor conditions. The LCP test facility structural system consists of six TF Coils, twelve coil-to-coil torsional restraining beams (torque rings), a central bucking post with base, and a Pulse Coil system. The NASTRAN Finite Element Structural Analysis computer Code was utilized to determine the distribution of deflections, forces, and stresses for each of the TF Coils, torque rings, and the central bucking post. Eleven load conditions were selected to represent probable test operations. Pulse Coils suspended in the bore of the test coil were energized to simulate the pulsed field environment characteristic of the TNS reactor system. The TORMAC Computer Code was utilized to develop the magnetic forces in the TF Coils for each of the eleven loading conditions examined, with or without the Pulse Coils energized. The TORMAC computer program output forces were used directly as input load conditions for the NASTRAN analyses. Results are presented which demonstrate the reliability of the LCTF under simulated reactor operating conditions

Superconducting poloidal coils for STARFIRE commercial reactor

International Nuclear Information System (INIS)

Wang, S.T.; Evans, K. Jr.; Turner, L.R.; Huang, Y.C.; Prater, R.; Alcorn, J.

1979-01-01

STARFIRE is considered to be the tenth commercial tokamak power plant. A preliminary design study on its superconducting poloidal coil system is presented. Key features of the design studies are: the elimination of the ohmic heating coil; the trade-off studies of the equilibrium field coil locations; and the development of a conceptual design for the superconducting equilibrium field coils. Described are the 100 kA cryostable conductor design, the coil structure, and evaluation of the coil forces

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

Science.gov (United States)

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

Strong contributions from vertical triads to helix-partner preferences in parallel coiled coils.

Science.gov (United States)

Steinkruger, Jay D; Bartlett, Gail J; Woolfson, Derek N; Gellman, Samuel H

2012-09-26

Pairing preferences in heterodimeric coiled coils are determined by complementarities among side chains that pack against one another at the helix-helix interface. However, relationships between dimer stability and interfacial residue identity are not fully understood. In the context of the "knobs-into-holes" (KIH) packing pattern, one can identify two classes of interactions between side chains from different helices: "lateral", in which a line connecting the adjacent side chains is perpendicular to the helix axes, and "vertical", in which the connecting line is parallel to the helix axes. We have previously analyzed vertical interactions in antiparallel coiled coils and found that one type of triad constellation (a'-a-a') exerts a strong effect on pairing preferences, while the other type of triad (d'-d-d') has relatively little impact on pairing tendencies. Here, we ask whether vertical interactions (d'-a-d') influence pairing in parallel coiled-coil dimers. Our results indicate that vertical interactions can exert a substantial impact on pairing specificity, and that the influence of the d'-a-d' triad depends on the lateral a' contact within the local KIH motif. Structure-informed bioinformatic analyses of protein sequences reveal trends consistent with the thermodynamic data derived from our experimental model system in suggesting that heterotriads involving Leu and Ile are preferred over homotriads involving Leu and Ile.

Power inverter design for ASDEX Upgrade saddle coils

Energy Technology Data Exchange (ETDEWEB)

Teschke, M., E-mail: teschke@ipp.mpg.de [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Suttrop, W.; Rott, M. [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)

2013-10-15

Highlights: ► A cost effective inverter topology for AUG's 16 in-vessel saddle coils has been found. ► Use of commercially available power modules is possible. ► Exchange of reactive power between multiple inverters is possible. ► Influence of electromagnetic noise to AUG's diagnostics was measured. ► Gas insulation of electric feed through significantly depends on magnetic fields. It is protected by fast turn-off circuit. -- Abstract: A set of 16 in-vessel saddle coils has been installed in the ASDEX Upgrade (AUG) experiment since the end of 2011 [1]. To achieve full performance, it is necessary to operate them with alternating current (AC) of arbitrary waveforms. To generate spatially resolved magnetic fields, it is required to allocate separate power inverters to every single coil. Therefore, different topologies are analyzed and compared. Studies of the commutation behavior of power stages, different pulse width modulation (PWM) schemes and single-phase-to-earth fault detection are executed. Experiments to evaluate the electromagnetic interference (EMI) of possible inverter topologies on the AUG diagnostics are done as well. A special focus is put on the feasibility of analyzed topologies using industrially available and fully assembled “power modules” to minimize development effort and costs.

Self-Assembly of Rod-Coil Block Copolymers

National Research Council Canada - National Science Library

Jenekhe, S

1999-01-01

... the self-assembly of new rod-coil diblock, rod- coil-rod triblock, and coil-rod-coil triblock copolymers from solution and the resulting discrete and periodic mesostmctares with sizes in the 100...

Poynting vector analysis for wireless power transfer between magnetically coupled coils with different loads.

Science.gov (United States)

Guo, Yunsheng; Li, Jiansheng; Hou, Xiaojuan; Lv, Xiaolong; Liang, Hao; Zhou, Ji; Wu, Hongya

2017-04-07

Wireless power transfer is a nonradiative type of transmission that is performed in the near-field region. In this region, the electromagnetic fields that are produced by both the transmitting and receiving coils are evanescent fields, which should not transmit energy. This then raises the question of how the energy can be transferred. Here we describe a theoretical study of the two evanescent field distributions at different terminal loads. It is shown that the essential principle of wireless energy transfer is the superposition of the two evanescent fields, and the resulting superimposed field is mediated through the terminal load. If the terminal load is either capacitive or inductive, then the superimposed field cannot transfer the energy because its Poynting vector is zero; in contrast, if the load is resistive, energy can then be conveyed from the transmitting coil to the receiving coil. The simulation results for the magnetic field distributions and the time-domain current waveforms agree very well with the results of the theoretical analysis. This work thus provides a comprehensive understanding of the energy transfer mechanism involved in the magnetic resonant coupling system.

GBNV encoded movement protein (NSm) remodels ER network via C-terminal coiled coil domain

Energy Technology Data Exchange (ETDEWEB)

Singh, Pratibha; Savithri, H.S., E-mail: bchss@biochem.iisc.ernet.in

2015-08-15

Plant viruses exploit the host machinery for targeting the viral genome–movement protein complex to plasmodesmata (PD). The mechanism by which the non-structural protein m (NSm) of Groundnut bud necrosis virus (GBNV) is targeted to PD was investigated using Agrobacterium mediated transient expression of NSm and its fusion proteins in Nicotiana benthamiana. GFP:NSm formed punctuate structures that colocalized with mCherry:plasmodesmata localized protein 1a (PDLP 1a) confirming that GBNV NSm localizes to PD. Unlike in other movement proteins, the C-terminal coiled coil domain of GBNV NSm was shown to be involved in the localization of NSm to PD, as deletion of this domain resulted in the cytoplasmic localization of NSm. Treatment with Brefeldin A demonstrated the role of ER in targeting GFP NSm to PD. Furthermore, mCherry:NSm co-localized with ER–GFP (endoplasmic reticulum targeting peptide (HDEL peptide fused with GFP). Co-expression of NSm with ER–GFP showed that the ER-network was transformed into vesicles indicating that NSm interacts with ER and remodels it. Mutations in the conserved hydrophobic region of NSm (residues 130–138) did not abolish the formation of vesicles. Additionally, the conserved prolines at positions 140 and 142 were found to be essential for targeting the vesicles to the cell membrane. Further, systematic deletion of amino acid residues from N- and C-terminus demonstrated that N-terminal 203 amino acids are dispensable for the vesicle formation. On the other hand, the C-terminal coiled coil domain when expressed alone could also form vesicles. These results suggest that GBNV NSm remodels the ER network by forming vesicles via its interaction through the C-terminal coiled coil domain. Interestingly, NSm interacts with NP in vitro and coexpression of these two proteins in planta resulted in the relocalization of NP to PD and this relocalization was abolished when the N-terminal unfolded region of NSm was deleted. Thus, the NSm

Large coil program support structure conceptual design

International Nuclear Information System (INIS)

Litherland, P.S.

1977-01-01

The purpose of the Large Coil Program (LCP) is to perform tests on both pool boiling and force cooled superconducting toroidal field coils. The tests will attempt to approximate conditions anticipated in an ignition tokamak. The test requirements resulted in a coil support design which accommodates up to six (6) test coils and is mounted to a structure capable of resisting coil interactions. The steps leading to the present LCP coil support structure design, details on selected structural components, and the basic assembly sequence are discussed

Coil protection calculator for TFTR

International Nuclear Information System (INIS)

Marsala, R.J.; Lawson, J.E.; Persing, R.G.; Senko, T.R.; Woolley, R.D.

1989-01-01

A new coil protection system (CPS) is being developed to replace the existing TFTR magnetic coil fault detector. The existing fault detector sacrifices TFTR operating capability for simplicity. The new CPS, when installed in October of 1988, will permit operation up to the actual coil stress limits parameters in real-time. The computation will be done in a microprocessor based Coil Protection Calculator (CPC) currently under construction at PPL. THe new CPC will allow TFTR to operate with higher plasma currents and will permit the optimization of pulse repetition rates. The CPC will provide real-time estimates of critical coil and bus temperatures and stresses based on real-time redundant measurements of coil currents, coil cooling water inlet temperature, and plasma current. The critical parameter calculations are compared to prespecified limits. If these limits are reached or exceeded, protection action will be initiated to a hard wired control system (HCS), which will shut down the power supplies. The CPC consists of a redundant VME based microprocessor system which will sample all input data and compute all stress quantities every ten milliseconds. Thermal calculations will be approximated every 10ms with an exact solution occurring every second. The CPC features continuous cross-checking of redundant input signal, automatic detection of internal failure modes, monitoring and recording of calculated results, and a quick, functional verification of performance via an internal test system. (author)

Test facility for PLT TF coils

International Nuclear Information System (INIS)

Hearney, J.; File, J.; Dreskin, S.

1975-01-01

Past experience with the model C stellerator and other toroidal field devices indicates that mechanical and electrical tests of a toroidal field coil prior to maximum field operation of the device is prudent and desirable. This paper describes a test program for the PLT-TF coils. The test stand consists of one test coil, two background coils and a steel supporting structure. The three coil configuration produces a 67.5 kG field at the inner conductor (38 kG at the bore center) and simulates a 1/R field distribution in the bore of the test coil. The resolution of the field force system and resultant stresses within the test structure are discussed. A test procedure is described which maximizes the information obtained from a 100,000 pulse program

High-resolution small field-of-view magnetic resonance image acquisition system using a small planar coil and a pneumatic manipulator in an open MRI scanner.

Science.gov (United States)

Miki, Kohei; Masamune, Ken

2015-10-01

Low-field open magnetic resonance imaging (MRI) is frequently used for performing image-guided neurosurgical procedures. Intraoperative magnetic resonance (MR) images are useful for tracking brain shifts and verifying residual tumors. However, it is difficult to precisely determine the boundary of the brain tumors and normal brain tissues because the MR image resolution is low, especially when using a low-field open MRI scanner. To overcome this problem, a high-resolution MR image acquisition system was developed and tested. An MR-compatible manipulator with pneumatic actuators containing an MR signal receiver with a small radiofrequency (RF) coil was developed. The manipulator had five degrees of freedom for position and orientation control of the RF coil. An 8-mm planar RF coil with resistance and inductance of 2.04 [Formula: see text] and 1.00 [Formula: see text] was attached to the MR signal receiver at the distal end of the probe. MR images of phantom test devices were acquired using the MR signal receiver and normal head coil for signal-to-noise ratio (SNR) testing. The SNR of MR images acquired using the MR signal receiver was 8.0 times greater than that of MR images acquired using the normal head coil. The RF coil was moved by the manipulator, and local MR images of a phantom with a 2-mm grid were acquired using the MR signal receiver. A wide field-of-view MR image was generated from a montage of local MR images. A small field-of-view RF system with a pneumatic manipulator was integrated in a low-field MRI scanner to allow acquisition of both wide field-of-view and high-resolution MR images. This system is promising for image-guided neurosurgery as it may allow brain tumors to be observed more clearly and removed precisely.

Using GRAPPA to improve autocalibrated coil sensitivity estimation for the SENSE family of parallel imaging reconstruction algorithms.

Science.gov (United States)

Hoge, W Scott; Brooks, Dana H

2008-08-01

Two strategies are widely used in parallel MRI to reconstruct subsampled multicoil image data. SENSE and related methods employ explicit receiver coil spatial response estimates to reconstruct an image. In contrast, coil-by-coil methods such as GRAPPA leverage correlations among the acquired multicoil data to reconstruct missing k-space lines. In self-referenced scenarios, both methods employ Nyquist-rate low-frequency k-space data to identify the reconstruction parameters. Because GRAPPA does not require explicit coil sensitivities estimates, it needs considerably fewer autocalibration signals than SENSE. However, SENSE methods allow greater opportunity to control reconstruction quality though regularization and thus may outperform GRAPPA in some imaging scenarios. Here, we employ GRAPPA to improve self-referenced coil sensitivity estimation in SENSE and related methods using very few auto-calibration signals. This enables one to leverage each methods' inherent strength and produce high quality self-referenced SENSE reconstructions. (c) 2008 Wiley-Liss, Inc.

Large coil test facility conceptual design report

International Nuclear Information System (INIS)

Nelms, L.W.; Thompson, P.B.; Mann, T.L.

1978-02-01

In the development of a superconducting toroidal field (TF) magnet for The Next Step (TNS) tokamak reactor, several different TF coils, about half TNS size, will be built and tested to permit selection of a design and fabrication procedure for full-scale TNS coils. A conceptual design has been completed for a facility to test D-shaped TF coils, 2.5 x 3.5-m bore, operating at 4-6 K, cooled either by boiling helium or by forced-flow supercritical helium. Up to six coils can be accommodated in a toroidal array housed in a single vacuum tank. The principal components and systems in the facility are an 11-m vacuum tank, a test stand providing structural support and service connections for the coils, a liquid nitrogen system, a system providing helium both as saturated liquid and at supercritical pressure, coils to produce a pulsed vertical field at any selected test coil position, coil power supplies, process instrumentation and control, coil diagnostics, and a data acquisition and handling system. The test stand structure is composed of a central bucking post, a base structure, and two horizontal torque rings. The coils are bolted to the bucking post, which transmits all gravity loads to the base structure. The torque ring structure, consisting of beams between adjacent coils, acts with the bucking structure to react all the magnetic loads that occur when the coils are energized. Liquid helium is used to cool the test stand structure to 5 K to minimize heat conduction to the coils. Liquid nitrogen is used to precool gaseous helium during system cooldown and to provide thermal radiation shielding

Coil embolization of an enlarging fusiform myxomatous cerebral aneurysm

Directory of Open Access Journals (Sweden)

Frances Lazarow, MD

2018-04-01

Full Text Available Myxomatous cerebral aneurysms are rare sequelae of cardiac atrial myxoma. These aneurysms are generally fusiform, multiple, and distal. Pathogenesis and evolution of these aneurysms is still debated. There are currently no guidelines on the management of aneurysms secondary to atrial myxoma. We present a case of a 52-year-old man with multiple fusiform aneurysms 3 years after resection of a left atrial myxoma. One of these aneurysms was followed with cerebral angiography and showed substantial interval enlargement. This aneurysm was subsequently embolized. All aneurysms were stable 6 months post-embolization. Keywords: Myxomatous aneurysm, Fusiform, Coil embolization

Normal zone detectors for a large number of inductively coupled coils

International Nuclear Information System (INIS)

Owen, E.W.; Shimer, D.W.

1983-01-01

In order to protect a set of inductively coupled superconducting magnets, it is necessary to locate and measure normal zone voltages that are small compared with the mutual and self-induced voltages. The method described in this report uses two sets of voltage measurements to locate and measure one or more normal zones in any number of coupled coils. One set of voltages is the outputs of bridges that balance out the self-induced voltages The other set of voltages can be the voltages across the coils, although alternatives are possible. The two sets of equations form a single combined set of equations. Each normal zone location or combination of normal zones has a set of these combined equations associated with it. It is demonstrated that the normal zone can be located and the correct set chosen, allowing determination of the size of the normal zone. Only a few operations take plae in a working detector: multiplication of a constant, addition, and simple decision-making. In many cases the detector for each coil, although weakly linked to the other detectors, can be considered to be independent. An example of the detector design is given for four coils with realistic parameters. The effect on accuracy of changes in the system parameters is discussed

Coil supporting device for a nuclear fusion device

International Nuclear Information System (INIS)

Kuno, Kazuo.

1976-01-01

Object: To reduce a thermal stress of a coil such as a magnetic limiter to minimize stress acting on a protective tube of the coil. Structure: A coil within a protective tube has its outer periphery surrounded and supported by a heat-resisting material such as ceramic at more than two positions suitably spaced lengthwise of a coil conductor, and heat insulating members are interposed between both sides of the coil and the protective tube so that it may be retained with respect to the width of the coil. Further, a heat-resisting resilient member is inserted in a clearance between an outer circumference and an inner circumference of the coil to allow a radial displacement of the coil. As a result, elongation of the coil due to thermal expansion may be escaped at the aforesaid two supports to reduce thermal stress of the coil and protective tube to support the coil within the protective tube in positively heat-resisting and insulating manner. (Kamimura, M.)

Optimal wireless receiver structure for omnidirectional inductive power transmission to biomedical implants.

Science.gov (United States)

Gougheri, Hesam Sadeghi; Kiani, Mehdi

2016-08-01

In order to achieve omnidirectional inductive power transmission to biomedical implants, the use of several orthogonal coils in the receiver side (Rx) has been proposed in the past. In this paper, the optimal Rx structure for connecting three orthogonal Rx coils and the power management is found to achieve the maximum power delivered to the load (PDL) in the presence of any Rx coil tilting. Unlike previous works, in which a separate power management has been used for each coil to deliver power to the load, different resonant Rx structures for connecting three Rx coils to a single power management are studied. In simulations, connecting three Rx coils with the diameters of 3 mm, 3.3 mm, and 3.6 mm in series and resonating them with a single capacitor at the operation frequency of 100 MHz led to the maximum PDL for large loads when the implant was tilted for 45o. This optimal Rx structure achieves higher PDL in worst-case scenarios as well as reduces the number of power managements to only one.

Eccentric Coil Test Facility (ECTF)

International Nuclear Information System (INIS)

Burn, P.B.; Walstrom, P.L.; Anderson, W.C.; Marguerat, E.F.

1975-01-01

The conceptual design of a facility for testing superconducting coils under some conditions peculiar to tokamak systems is given. A primary element of the proposed facility is a large 25 MJ background solenoid. Discussions of the mechanical structure, the stress distribution and the thermal stability for this coil are included. The systems for controlling the facility and diagnosing test coil behavior are also described

Superconducting coil protection

International Nuclear Information System (INIS)

Woods, E.L.

1975-01-01

The protection system is based on a two-phase construction program. Phase I is the development of a reliable hardwired relay control system with a digital loop utilizing firmware and a microprocessor controller. Phase II is an expansion of the digital loop to include many heretofore unmonitored coil variables. These new monitored variables will be utilized to establish early quench detection and to formulate confirmation techniques of the quench detection mechanism. Established quench detection methods are discussed and a new approach to quench detection is presented. The new circuit is insensitive to external pulsed magnetic fields and the associated induced voltages. Reliability aspects of the coil protection system are discussed with respect to shutdowns of superconducting coil systems. Redundance and digital system methods are presented as related topics

Gradient coil system for nuclear magnetic resonance apparatus

International Nuclear Information System (INIS)

Frese, G.; Siebold, H.

1984-01-01

A gradient coil system for an image-generating, nuclear magnetic resonance tomographic apparatus, particularly a zeugmatographic apparatus. The gradient coil system is arranged on a support body of rotational symmetry, illustratively a hollow cylindrical support body, having an axis which extends along the z-direction of an x, y, z coordinate system which has an origin in the center of imaging region. The gradient coil system contains two pairs of toroidal individual coils which are arranged symmetrically with respect to an x-y plane which extends through the center of the imaging region and which are arranged perpendicular to the z-axis. The direction of current flow in the individual coils of a coil pair is opposite to the direction of flow in the individual coils of the other coil pair. Moreover, further sets of coils are provided for generating field gradient Gx in the x-direction, and Gy in the y-direction. The hollow cylindrical shape of the support body on which the individual coils are arranged permit an imaging region having a substantially spherical volume with a substantially constant field gradient Gz to be achieved. Each of the coils has a predetermined linkage factor which corresponds to the product of the current flowing through the number of coil turns of the coil. Those coils which are arranged further from the plane of symmetry have a substantially larger linkage factor than the coils which are nearer to the plane of symmetry

Sub-20 nm Stable Micelles Based on a Mixture of Coiled-Coils: A Platform for Controlled Ligand Presentation.

Science.gov (United States)

Ang, JooChuan; Ma, Dan; Jung, Benson T; Keten, Sinan; Xu, Ting

2017-11-13

Ligand-functionalized, multivalent nanoparticles have been extensively studied for biomedical applications from imaging agents to drug delivery vehicles. However, the ligand cluster size is usually heterogeneous and the local valency is ill-defined. Here, we present a mixed micelle platform hierarchically self-assembled from a mixture of two amphiphilic 3-helix and 4-helix peptide-polyethylene glycol (PEG)-lipid hybrid conjugates. We demonstrate that the local multivalent ligand cluster size on the micelle surface can be controlled based on the coiled-coil oligomeric state. The oligomeric states of mixed peptide bundles were found to be in their individual native states. Similarly, mixed micelles indicate the orthogonal self-association of coiled-coil amphiphiles. Using differential scanning calorimetry, fluorescence recovery spectroscopy, and coarse-grained molecular dynamics simulation, we studied the distribution of coiled-coil bundles within the mixed micelles and observed migration of coiled-coils into nanodomains within the sub-20 nm mixed micelle. This report provides important insights into the assembly and formation of nanophase-separated micelles with precise control over the local multivalent state of ligands on the micelle surface.

Discussion of discrete D shape toroidal coil

International Nuclear Information System (INIS)

Kaiho, Katsuyuki; Ohara, Takeshi; Agatsuma, Ko; Onishi, Toshitada

1988-01-01

A novel design for a toroidal coil, called the D shape coil, was reported by J. File. The coil conductors are in pure tension and then subject to no bending moment. This leads to a smaller number of emf supports in a simpler configuration than that with the conventional toroidal coil of circular cross-section. The contours of the D shape are given as solutions of a differential equation. This equation includes the function of the magnetic field distribution in the conductor region which is inversely proportional to the winding radius. It is therefore important to use the exact magnetic field distribution. However the magnetic field distribution becomes complicated when the D shape toroidal coil is comprised of discrete coils and also depends on the D shape configuration. A theory and a computer program for designing the practical pure-tension toroidal coil are developed. Using this computer code, D shape conductors are calculated for various numbers of discrete coils and the results are compared. Electromagnetic forces in the coils are also calculated. It is shown that the hoop stress in the conductors depends only on the total ampere-turns of the coil when the contours of the D shape are similar. (author)

Electric field control methods for foil coils in high-voltage linear actuators

NARCIS (Netherlands)

Beek, van T.A.; Jansen, J.W.; Lomonova, E.A.

2015-01-01

This paper describes multiple electric field control methods for foil coils in high-voltage coreless linear actuators. The field control methods are evaluated using 2-D and 3-D boundary element methods. A comparison is presented between the field control methods and their ability to mitigate

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

International Nuclear Information System (INIS)

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

2015-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Terawaki, Shin-ichi, E-mail: terawaki@gunma-u.ac.jp [Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); SPring-8 Center, RIKEN, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Yoshikane, Asuka [Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); SPring-8 Center, RIKEN, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Higuchi, Yoshiki [Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Department of Picobiology, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); SPring-8 Center, RIKEN, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Wakamatsu, Kaori [Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); SPring-8 Center, RIKEN, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

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.

An analysis of 3D solvation structure in biomolecules: application to coiled coil serine and bacteriorhodopsin.

Science.gov (United States)

Hirano, Kenji; Yokogawa, Daisuke; Sato, Hirofumi; Sakaki, Shigeyoshi

2010-06-17

Three-dimensional (3D) solvation structure around coiled coil serine (Coil-Ser) and inner 3D hydration structure in bacteriorhodopsin (bR) were studied using a recently developed method named multicenter molecular Ornstein-Zernike equation (MC-MOZ) theory. In addition, a procedure for analyzing the 3D solvent distribution was proposed. The method enables us to calculate the coordination number of solvent water as well as the strength of hydrogen bonding between the water molecule and the protein. The results for Coil-Ser and bR showed very good agreement with the experimental observations.

PET attenuation correction for rigid MR Tx/Rx coils from 176Lu background activity

Science.gov (United States)

Lerche, Christoph W.; Kaltsas, Theodoris; Caldeira, Liliana; Scheins, Jürgen; Rota Kops, Elena; Tellmann, Lutz; Pietrzyk, Uwe; Herzog, Hans; Shah, N. Jon

2018-02-01

One challenge for PET-MR hybrid imaging is the correction for attenuation of the 511 keV annihilation radiation by the required RF transmit and/or RF receive coils. Although there are strategies for building PET transparent Tx/Rx coils, such optimised coils still cause significant attenuation of the annihilation radiation leading to artefacts and biases in the reconstructed activity concentrations. We present a straightforward method to measure the attenuation of Tx/Rx coils in simultaneous MR-PET imaging based on the natural 176Lu background contained in the scintillator of the PET detector without the requirement of an external CT scanner or PET scanner with transmission source. The method was evaluated on a prototype 3T MR-BrainPET produced by Siemens Healthcare GmbH, both with phantom studies and with true emission images from patient/volunteer examinations. Furthermore, the count rate stability of the PET scanner and the x-ray properties of the Tx/Rx head coil were investigated. Even without energy extrapolation from the two dominant γ energies of 176Lu to 511 keV, the presented method for attenuation correction, based on the measurement of 176Lu background attenuation, shows slightly better performance than the coil attenuation correction currently used. The coil attenuation correction currently used is based on an external transmission scan with rotating 68Ge sources acquired on a Siemens ECAT HR  +  PET scanner. However, the main advantage of the presented approach is its straightforwardness and ready availability without the need for additional accessories.

Coil supporting device for thermonuclear device

International Nuclear Information System (INIS)

Okubo, Minoru; Ando, Toshiro; Ota, Mitsuru; Ishimura, Masabumi.

1979-01-01

Purpose: To lower the bending stress exerted on coils thereby preventing the coils from deformation by branching the outer circumferential support frames of coil support frames disposed at an equal pitch circumferentially to the coils into plurality, and integrally forming them to the inner circumferential support frames. Constitution: Each of the support frames for supporting poloidal coils winding around a vacuum vessel is bisected at the radial midway so that the outer circumferential branches are disposed at an equal pitch and they are formed integrally with the inner circumferential support frames. The inner circumferential support frames are fixed by support posts on a bed and the outer circumferential support frames are mounted to the outer edge of wedge-like support posts. Accordingly, if the coils expand outwardly upon increase in the temperature, the stress exerted on the support frame can be decreased. (Yoshino, Y.)

Impact of coil price knowledge by the operator on the cost of aneurysm coiling. A single center study.

Science.gov (United States)

Finitsis, Stephanos; Fahed, Robert; Gaulin, Ian; Roy, Daniel; Weill, Alain

2017-09-15

Endovascular treatment of aneurysms with coils is among the most frequent treatments in interventional neuroradiology, and represents an important expense. Each manufacturer has created several types of coils, with prices varying among brands and coil types. The objective of this study was to assess the impact of cost awareness of the exact price of each coil by the operating physician on the total cost of aneurysm coiling. This was a comparative study conducted over 1 year in a single tertiary care center. The reference cohort and the experimental cohort consisted of all aneurysm embolization procedures performed during the first 6 months and the last 6 months, respectively. During the second period, physicians were given an information sheet with the prices of all available coils and were requested to look at the sheet during each procedure with the instruction to try to reduce the total cost of the coils used. Expenses related to the coiling procedures during each period were compared. 77 aneurysms (39 ruptured) in the reference cohort and 73 aneurysms (36 ruptured) in the experimental cohort were treated, respectively. There was no statistically significant difference regarding aneurysm location and mean size. The overall cost of the coiling procedures, the mean number of coils used per procedure, and the median cost of each procedure did not differ significantly between the two cohorts. Awareness of the precise price of coils by operators without any additional measure did not have a scientifically proven impact on the cost of aneurysm embolization. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Magnetic field coil in nuclear fusion device

International Nuclear Information System (INIS)

Yamaguchi, Mitsugi; Takano, Hirohisa.

1975-01-01

Object: To provide an electrical-insulatively stabilized magnetic field coil in nuclear fusion device, restraining an increase in voltage when plasma current is rapidly changed. Structure: A magnetic field coil comprises coils arranged coaxial with respective vacuum vessels, said coils being wound in positive and reverse polarities so as to form a vertical magnetic field within the plasma. The coils of the positive polarity are arranged along the vacuum vessel inside of an axis vertical in section of the annular plasma and are arranged symmetrically up and down of a horizontal axis. On the other hand, the coils of the reverse polarity are arranged along the vacuum vessel outside of a vertical axis and arranged symmetrically up and down of the horizontal axis. These positive and reverse polarity coils are alternately connected in series, and lead portions of the coils are connected to a power source by means of connecting wires. In this case, lead positions of the coils are arranged in one direction, and the connecting wires are disposed in closely contact relation to offset magnetic fields formed by the connecting wires each other. (Kawakami, Y.)

Coil supporting device in nuclear fusion apparatus

International Nuclear Information System (INIS)

Hoshi, Ryo; Imura, Yasuya.

1974-01-01

Object: To secure intermediate fittings with a coil fixed thereon by an insulating tape to a fixed body by means of fittings, thereby supporting the coil in a narrow space. Structure: A coil is secured to intermediate fittings by means of an insulating tape, after which the intermediate fittings is mounted on a fixed body through fittings to support the coil in a narrow clearance portion between a plasma sealed vessel and a main coil. (Kamimura, M.)

The SMES model coil. Fabrication

International Nuclear Information System (INIS)

Hanai, Satoshi; Nakamoto, Kazunari; Takahashi, Nobuji

1998-01-01

A SMES model coil was fabricated as R and D item in the development of component technologies for a 480 MJ/20 MW SMES pilot plant. The coil consists of four double-pancake windings. The coil is the same diameter but half the number of pancakes that will be needed for a SMES pilot plant. The NbTi cable-in-conduit conductor and superconducting joints between the double pancakes are cooled by a forced flow of supercritical helium. Prior to fabrication, various characteristics of the cable-in-conduit were measured by full-sized short samples from actual conductors and by scaled short samples from scaled conductors. The critical current of the scaled short samples was in agreement with that calculated from one strand of the conductor. The impedance between arbitrary dual-oxide coated strands in the full-size conductor was measured to be smaller than that obtained from two Cr-plated strands, which showed a good degree of stability in another coil. It was estimated that oxide-coated conductors would have high stability. Through fabrication of a model coil, it was demonstrated that a large forced-flow coil for a small-scale 100 kWh SMES device could be manufactured. (author)

The SMES model coil. Fabrication

Energy Technology Data Exchange (ETDEWEB)

Hanai, Satoshi; Nakamoto, Kazunari; Takahashi, Nobuji [Toshiba Corp., Yokohama, Kanagawa (Japan)] [and others

1998-07-01

A SMES model coil was fabricated as R and D item in the development of component technologies for a 480 MJ/20 MW SMES pilot plant. The coil consists of four double-pancake windings. The coil is the same diameter but half the number of pancakes that will be needed for a SMES pilot plant. The NbTi cable-in-conduit conductor and superconducting joints between the double pancakes are cooled by a forced flow of supercritical helium. Prior to fabrication, various characteristics of the cable-in-conduit were measured by full-sized short samples from actual conductors and by scaled short samples from scaled conductors. The critical current of the scaled short samples was in agreement with that calculated from one strand of the conductor. The impedance between arbitrary dual-oxide coated strands in the full-size conductor was measured to be smaller than that obtained from two Cr-plated strands, which showed a good degree of stability in another coil. It was estimated that oxide-coated conductors would have high stability. Through fabrication of a model coil, it was demonstrated that a large forced-flow coil for a small-scale 100 kWh SMES device could be manufactured. (author)

Remote maintenance of tandem mirror hybrid coils

International Nuclear Information System (INIS)

Dietz, L.P.

1983-01-01

Hybrid Coils (superconducting coils with normal conducting inserts) are being employed with increasing frequency on Tandem Mirror Devices to obtain high field strengths. The normal conducting copper inserts are short lived in comparison to their encircling superconductors. It becomes desirable, therefore, to devise design features and maintenance procedures to replace the inner normal conducting coils without simultaneously replacing the longer lived (and significantly more costly) superconducting coils. The high neutron wall loadings require that the task be accomplished by remote control. The approach is to permanently mount the coil assemblies on track mounted carriages which serve, during machine operation merely as structural supports, but during maintenance procedures as moveable transport devices. The carriages incorporate all necessary provisions to facilitate remote maintenance operations and to adjust and align the coil assemblies with respect to adjacent machine components. The vacuum vessel is severed on both sides of the hybrid coil by means of a remote cutting machine. The entire coil is transported horizontally, normal to the machine axis to a nearby repair station. Prepositioned carriage mounted repair equipment at the repair station withdraws the damaged normal coil as a single entity and inserts a preassembled spare unit. The repaired hybrid coil is reassembled to the reactor. A cost and risk effective procedure has been evolved to maintain one of the more critical components of a Tandem Mirror Machine

BI-ground microstrip array coil vs. conventional microstrip array coil for mouse imaging at 7 tesla

Science.gov (United States)

Hernández, Ricardo; Terrones, M. A. López; Jakob, P. M.

2012-10-01

At high field strengths, the need for more efficient high frequency coils has grown. Since the radiation losses and the interaction between coil and sample increase proportionally to field strength, the quality factor (Q) and the sensitivity of the coil decrease as consequence of these negative effects. Since Zhang et al proposed in 2001 a new surface coil based on the microstrip transmission line for high frequency, different Tx-Rx phased arrays based on this concept have been already introduced in animal and whole body systems at high field strengths, each of them with different modifications in order to get better field homogeneity, SNR or isolation between coil elements in the array. All these arrays for animals systems have been built for rat imaging. One of these modifications is called BI-Ground Microstrip Array Coil (BIGMAC). The implementation of a smaller two-channel BIGMAC design for mouse imaging is studied and its performance compared to a two-channel conventional Microstrip array at 7 Tesla, the higher isolation by using BIGMAC elements in comparison with conventional Microstrip elements is shown in this work.

Coil supporting device in a nuclear fusion device

International Nuclear Information System (INIS)

Takano, Hirohisa; Sasaki, Katsutoki.

1976-01-01

Object: To slide a vacuum vessel in the nuclear fusion device and a coil within the vacuum vessel and to mount the coil within the vacuum vessel in a manner that it may not be moved by an electromagnetic force, thereby preventing stress from being produced in the coil. Structure: A coil supporting plate mounted at upper and lower parts prevents damage to an insulation of the coil, said coil being held in a U-shaped groove, and can be moved integral with the coil by the action of a roller bearing with a plurality of needle-like rollers arranged in parallel. The coil supporting plate has a plurality of projections disposed on the lower surface thereof, and flat springs are placed in the projections one over another so that the spring action exerted in the lower plate causes the coil to be resiliently bias in a direction of an electromagnetic force applied thereto and to support the coil. (Yoshino, Y.)

A novel coil array for combined TMS/fMRI experiments at 3 T.

Science.gov (United States)

Navarro de Lara, Lucia I; Windischberger, Christian; Kuehne, Andre; Woletz, Michael; Sieg, Jürgen; Bestmann, Sven; Weiskopf, Nikolaus; Strasser, Bernhard; Moser, Ewald; Laistler, Elmar

2015-11-01

To overcome current limitations in combined transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) studies by employing a dedicated coil array design for 3 Tesla. The state-of-the-art setup for concurrent TMS/fMRI is to use a large birdcage head coil, with the TMS between the subject's head and the MR coil. This setup has drawbacks in sensitivity, positioning, and available imaging techniques. In this study, an ultraslim 7-channel receive-only coil array for 3 T, which can be placed between the subject's head and the TMS, is presented. Interactions between the devices are investigated and the performance of the new setup is evaluated in comparison to the state-of-the-art setup. MR sensitivity obtained at the depth of the TMS stimulation is increased by a factor of five. Parallel imaging with an acceleration factor of two is feasible with low g-factors. Possible interactions between TMS and the novel hardware were investigated and were found negligible. The novel coil array is safe, strongly improves signal-to-noise ratio in concurrent TMS/fMRI experiments, enables parallel imaging, and allows for flexible positioning of the TMS on the head while ensuring efficient TMS stimulation due to its ultraslim design. © 2014 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Status of the Swiss LCT-coil

International Nuclear Information System (INIS)

Zichy, J; Benz, H.; Horvath, I.; Jakob, B.; Marinucci, C.; Vecsey, G.; Weymuth, P.; Zellweger, J.

1983-01-01

The Swiss coil is a forced flow coil cooled by supercritical helium. A brief review of the design considerations, some of its specific features, and the progress in fabrication are described. A discussion of both the instrumentation and the cryogenic characteristics of the coil is presented

Hybrid equilibrium field coils for the ORNL TNS

International Nuclear Information System (INIS)

Peng, Y.K.M.; Strickler, D.J; Dory, R.A.

1977-01-01

In this study, we make a comparative study of the power supplies required by interior and exterior [to the toroidal field (TF) coils] equilibrium field coils that are separately appropriate for high-β, D-shaped plasmas in TNS. It is shown that the interior coils need power supplies that are an order of magnitude below those required by the exterior coils (while the latter case is much less difficult to build than the former). A hybrid EF coil concept is proposed that combines the interior and the exterior coils to retain their advantages in avoiding large interior coils while lowering the power supplied to the exterior coils by an order of magnitude

Effect of Inductive Coil Shape on Sensing Performance of Linear Displacement Sensor Using Thin Inductive Coil and Pattern Guide

Directory of Open Access Journals (Sweden)

Hiroyuki Wakiwaka

2011-11-01

Full Text Available This paper discusses the effect of inductive coil shape on the sensing performance of a linear displacement sensor. The linear displacement sensor consists of a thin type inductive coil with a thin pattern guide, thus being suitable for tiny space applications. The position can be detected by measuring the inductance of the inductive coil. At each position due to the change in inductive coil area facing the pattern guide the value of inductance is different. Therefore, the objective of this research is to study various inductive coil pattern shapes and to propose the pattern that can achieve good sensing performance. Various shapes of meander, triangular type meander, square and circle shape with different turn number of inductive coils are examined in this study. The inductance is measured with the sensor sensitivity and linearity as a performance evaluation parameter of the sensor. In conclusion, each inductive coil shape has its own advantages and disadvantages. For instance, the circle shape inductive coil produces high sensitivity with a low linearity response. Meanwhile, the square shape inductive coil has a medium sensitivity with higher linearity.

Fabrication of the KSTAR toroidal field coil structure

International Nuclear Information System (INIS)

Choi, C.H.; Sa, J.W.; Park, H.K.; Hong, K.H.; Shin, H.; Kim, H.T.; Bak, J.S.; Lee, G.S.; Kwak, J.H.; Moon, H.G.; Yoon, H.H.; Lee, J.W.; Lee, S.K.; Song, J.Y.; Nam, K.M.; Byun, S.E.; Kim, H.C.; Ha, E.T.; Ahn, H.J.; Kim, D.S.; Lee, J.S.; Park, K.H.; Hong, C.D.

2005-01-01

The KSTAR toroidal field (TF) coil structure is under fabrication upon completion of engineering design and prototype construction. The prototype TF coil structure has been fabricated within allowable tolerances. Encasing of the prototype TF coil (TF00) in the prototype structure has been carried out through major processes involving a coil encasing, an enclosing weld, a vacuum pressure impregnation, and an outer surface machining. During the enclosing weld of the TF00 coil structure, we have measured temperatures and stresses on the coil surface. Assembly test had been performed with the TF00 coil structure. We have chosen Type 316LN as material of the TF coil structure. We used the narrow-gap TIG welding method. Doosan Heavy Industries and Construction Company (DHI) will complete the fabrication of the TF coil structure in Feb. 2006. (author)

Coil concepts for rapid and motion-compensated MR-Imaging of small animals

International Nuclear Information System (INIS)

Korn, Matthias

2009-01-01

In this work radiofrequency-coils for the imaging of small animals in clinical whole-body MRI-systems were developed. Therefore in a first step single-channel solenoids were designed and characterized. The solenoids had two and three windings respectively, which were implemented as double wires to increase the homogeneity of the receive profile. These coils allow the acquisition of whole-body images of mice with high signal-to-noise ratio and homogeneity over a distance of at least 6.3 cm. Since many imaging experiments require rapid image acquisition, in the next step a novel coil concept was developed, which, due to its geometry, enables parallel imaging in arbitrary directions. A prototype was assembled and tested on phantom and small-animal experiments. With an accelerating factor of R=2, the difference of the SNR in all directions from the theoretical maximum, was less than 1%. In order to compensate physiological motion by the self-gating technique, in this work a coil is presented for the first time, which selectively amplifies the self-gating signal, while - due to a optical detuning technique - preserving the homogeneous illumination of the image. In vivo experiments on a small animal show an amplification of the self-gating signal by at least 40%. (orig.)

Startup of Large Coil Test Facility

International Nuclear Information System (INIS)

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

1985-01-01

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

Startup of Large Coil Test Facility

International Nuclear Information System (INIS)

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

Coil spring venting arrangement

International Nuclear Information System (INIS)

McCugh, R.M.

1975-01-01

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

Power loss problems in EXTRAP coil systems

International Nuclear Information System (INIS)

Lehnert, B.

1977-02-01

The Ohmic power loss in the coils of external ring traps is minimized with respect to the thermonuclear power production. In the case of the DT-reaction this leads to dimensions and power densities being relevant to full-scale reactors. Not only superconducting or refrigerated coil windings can thus be used, but also hot-coil systems which are operated at several hundred degrees centrigrade and form part of a steam cycle and power extraction system. For hot coils the problems of void formation and tritium regeneration have to be further examined. The high beta value leads to moderately large coil stresses. Finally, replacement and repair become simplified by the present coil geometry. (Auth.)

Performance of the Conduction-Cooled LDX Levitation Coil

Science.gov (United States)

Michael, P. C.; Schultz, J. H.; Smith, B. A.; Titus, P. H.; Radovinsky, A.; Zhukovsky, A.; Hwang, K. P.; Naumovich, G. J.; Camille, R. J.

2004-06-01

The Levitated Dipole Experiment (LDX) was developed to study plasma confinement in a dipole magnetic field. Plasma is confined in the magnetic field of a 680-kg Nb3Sn Floating Coil (F-coil) that is electromagnetically supported at the center of a 5-m diameter by 3-m tall vacuum chamber. The Levitation Coil (L-coil) is a 2800-turn, double pancake winding that supports the weight of the F-coil and controls its vertical position within the vacuum chamber. The use of high-temperature superconductor (HTS) Bi-2223 for the L-coil minimizes the electrical and cooling power needed for levitation. The L-coil winding pack and support plate are suspended within the L-coil cryostat and cooled by conduction to a single-stage cryocooler rated for 25-W heat load at approximately 20 K. The coil current leads consist of conduction-cooled copper running from room temperature to 80 K and a pair of commercially-available, 150-A HTS leads. An automatically filled liquid-nitrogen reservoir provides cooling for the coil's radiation shield and for the leads' 80-K heat stations. This paper discusses the L-coil system design and its observed cryogenic performance.

Active internal corrector coils

International Nuclear Information System (INIS)

Thompson, P.A.; Cottingham, J.; Dahl, P.

1986-01-01

Trim or corrector coils to correct main magnet field errors and provide higher multipole fields for beam optics purposes are a standard feature of superconducting magnet accelerator systems. This paper describes some of the design and construction features of powered internal trim coils and a sampling of the test results obtained

Coil for a nuclear fusion device

International Nuclear Information System (INIS)

Kadotani, Kenzo.

1975-01-01

Object: To provide a thin nuclear fusion coil having good thermal insulation and insulating properties in which mica and glass materials are wound round conductors subjected to varnish treatment and hardened, which is then sealed into a metallic case along with negative gases of more than two atmospheric pressures. Structure: A plurality of conductors impregnated with varnish are hardened by a rare insulating layer, after which it is coated with a layer of mica not impregnated with varnish and a layer of glass substance and is then received into a metallic case and filled under pressure with negative gases at a pressure more than two atmospheric pressures. (Kamimura, M.)

Coil Optimization for HTS Machines

DEFF Research Database (Denmark)

Mijatovic, Nenad; Jensen, Bogi Bech; Abrahamsen, Asger Bech

An optimization approach of HTS coils in HTS synchronous machines (SM) is presented. The optimization is aimed at high power SM suitable for direct driven wind turbines applications. The optimization process was applied to a general radial flux machine with a peak air gap flux density of ~3T...... is suitable for which coil segment is presented. Thus, the performed study gives valuable input for the coil design of HTS machines ensuring optimal usage of HTS tapes....

Electromagnetic-coil (EM-coil) measurement technique to verify presence of metal/absence of oxide attribute

International Nuclear Information System (INIS)

Fuller, J.L.; Hockey, R.L.

2001-01-01

This paper summarizes how an Electromagnetic-coil (EM-coil) measurement technique can be used to discriminate between plutonium metal and plutonium oxide inside sealed storage containers. As evidence, measurements on a variety of metals and their oxides are presented. This non-radiation measurement method provides assurance of the 'presence of metal/absence of oxide' attribute in less than a minute. During initial development, researchers at Pacific Northwest Laboratory have demonstrated the ability of this method to discriminate between aluminum and aluminum oxide placed inside an AT-400R storage container (total stainless steel wall thickness of over 2.5 cm). Similar results are expected, since Pu metal is electrically conductive and a Pu oxide behaves as an electrical insulator. At this writing, work is underway to perform the same demonstration using plutonium and plutonium oxide. Similar success has been demonstrated when using ALR-8 storage containers (basically carbon steel drums). Within these container types two scenarios have been explored. 1.) The same configuration made from different metals for demonstrating material property effects. A clear distinction was seen between the slight alloy changes among various forms of aluminum and brass in the same configuration. 2.) The same metal configured differently to demonstrate how mass distribution affects the EM signature. Hundreds of bb's (each about 2 mm in diameter) were placed in different containers to show how a slight change in distribution will affect the EM signature. With a five percent change in bb container diameter, the resulting EM signature changes are clear. This measurement method offers an extremely wide dynamic range resulting from its sensitivity to the wide range in electrical conductivity and magnetic permeability found in most metals and alloys. In fact, electrical conductivity spans the widest spectrum of all the known physical properties. Most insulators such as the oxides cover the

Conceptual Design of Alborz Tokamak Poloidal Coils System

Science.gov (United States)

Mardani, M.; Amrollahi, R.

2013-04-01

The Alborz tokamak is a D-shape cross section tokamak that is under construction in Amirkabir University of Technology. One of the most important parts of tokamak design is the design of the poloidal field system. This part includes the numbers, individual position, currents and number of coil turns of the magnetic field coils. Circular cross section tokamaks have Vertical Field system but since the elongation and triangularity of plasma cross section shaping are important in improving the plasma performance and stability, the poloidal field coils are designed to have a shaped plasma configuration. In this paper the design of vertical field system and the magnetohydrodynamic equilibrium of axisymmetric plasma, as given by the Grad-Shafranov equation will be discussed. The poloidal field coils system consists of 12 circular coils located symmetrically about the equator plane, six inner PF coils and six outer PF coils. Six outer poloidal field coils (PF) are located outside of the toroidal field coils (TF), and six inner poloidal field coils are wound on the inner legs and are located outside of a vacuum vessel.

Polymer cancerostatics with a coiled coil motif targeted against murine leukemia

Czech Academy of Sciences Publication Activity Database

Pechar, Michal; Pola, Robert; Janoušková, Olga; Sieglová, Irena; Král, Vlastimil; Fábry, Milan; Tomalová, Barbora; Kovář, Marek

2017-01-01

Roč. 6, 4 (Suppl) (2017), s. 36 ISSN 2325-9604. [International Conference and Exhibition on Nanomedicine and Drug Delivery. 29.05.2017-31.05.2017, Osaka] R&D Projects: GA ČR(CZ) GA16-17207S Institutional support: RVO:61389013 ; RVO:68378050 ; RVO:61388971 Keywords : coiled coil * polymer cancerostatics * active targeting Subject RIV: CD - Macromolecular Chemistry; EC - Immunology (MBU-M) https://www.scitechnol.com/conference-abstracts/scientific-tracks-abstracts/nanodelivery-2017-proceedings.html

Solutions for Safe Hot Coil Evacuation and Coil Handling in Case of Thick and High Strength Steel

Directory of Open Access Journals (Sweden)

Sieberer Stefan

2016-01-01

Full Text Available Currently hot rolling plants are entering the market segment for thick gauges and high strength steel grades where the elastic bending property of the strip leads to internal forces in the coil during coiling operation. The strip tends to open. Primetals is investigating several possibilities to facilitate safe coil evacuation and coil handling under spring-back conditions. The contribution includes finite element models of such mechanical solutions. Results of parameter variation and stability limits of case studies are presented in the paper.

An inflatable surface coil for rectal imaging

International Nuclear Information System (INIS)

Martin, J.F.; Hajek, P.C.; Baker, L.L.; Gylys-Morin, V.; Mattrey, R.F.

1986-01-01

Surface coils have become ubiquitous in MR imaging of the body because of substantial gains in signal-to-noise ratio. Unfortunately, there are some anatomic regions, such as the prostate, for which surface coils have insufficient depth sensitivity. The authors have developed an inflatable, distributed capacitance, passively decoupled surface coil which is collapsed for insertion and reinflated for imaging. Images of the prostate are dramatically improved due to proximity of the coil. Lesions in cadaver specimens were observed which were not seen with body coil imaging. Clinical trials are expected to begin in September

Wireless power transmission to an electromechanical receiver using low-frequency magnetic fields

International Nuclear Information System (INIS)

Challa, Vinod R; Arnold, David P; Mur-Miranda, Jose Oscar

2012-01-01

A near-field, electrodynamically coupled wireless power transmission system is presented that delivers electrical power from a transmitter coil to a compact electromechanical receiver. The system integrates electromechanical energy conversion and mechanical resonance to deliver power over a range of distances using low-amplitude, low-frequency magnetic fields. Two different receiver orientations are investigated that rely on either the force or the torque induced on the receiver magnet at separation distances ranging from 2.2 to 10.2 cm. Theoretical models for each mode compare the predicted performance with the experimental results. For a 7.1 mA pk sinusoidal current supplied to a transmitter coil with a 100 cm diameter, the torque mode receiver orientation has a maximum power transfer of 150 μW (efficiency of 12%) at 2.2 cm at its resonance frequency of 38.4 Hz. For the same input current to the transmitter, the force mode receiver orientation has a maximum power transfer of 37 μW (efficiency of 4.1%) at 3.1 cm at its resonance frequency of 38.9 Hz. (paper)

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

Science.gov (United States)

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. 2010 Wiley-Liss, Inc.

Development of Ground Coils with Low Eddy Current Loss by Applying the Compression Molding Method after the Coil Winding

Science.gov (United States)

Suzuki, Masao; Aiba, Masayuki; Takahashi, Noriyuki; Ota, Satoru; Okada, Shigenori

In a magnetically levitated transportation (MAGLEV) system, a huge number of ground coils will be required because they must be laid for the whole line. Therefore, stable performance and reduced cost are essential requirements for the ground coil development. On the other hand, because the magnetic field changes when the superconducting magnet passes by, an eddy current will be generated in the conductor of the ground coil and will result in energy loss. The loss not only increases the magnetic resistance for the train running but also brings an increase in the ground coil temperature. Therefore, the reduction of the eddy current loss is extremely important. This study examined ground coils in which both the eddy current loss and temperature increase were small. Furthermore, quantitative comparison for the eddy current loss of various magnet wire samples was performed by bench test. On the basis of the comparison, a round twisted wire having low eddy current loss was selected as an effective ground coil material. In addition, the ground coils were manufactured on trial. A favorable outlook to improve the size accuracy of the winding coil and uneven thickness of molded resin was obtained without reducing the insulation strength between the coil layers by applying a compression molding after winding.

Argonne National Laboratory superconducting pulsed coil program

International Nuclear Information System (INIS)

Wang, S.T.; Kim, S.H.

1979-01-01

The main objectives are to develop high current (approx. 100 kA) cryostable cable configurations with reasonably low ac losses, to build a demonstration pulsed coil, and to develop a rather inexpensive large fiberglass reinforced helium cryostat. A 1.5-MJ cryostable pulsed superconducting coil has been developed and constructed at ANL. The coil has a peak field of 4.5 T at an operating current of 11.0 kA. A large inexpensive plastic cryostat has been developed for testing the pulsed coil. The coil has been pulsed with a maximum dB/dt of 11 T/s. The coil was pulsed more than 4000 cycles. Detailed results of the ac loss measurements and the current sharing of the cryostability will be described

Self-calibrated multiple-echo acquisition with radial trajectories using the conjugate gradient method (SMART-CG).

Science.gov (United States)

Jung, Youngkyoo; Samsonov, Alexey A; Bydder, Mark; Block, Walter F

2011-04-01

To remove phase inconsistencies between multiple echoes, an algorithm using a radial acquisition to provide inherent phase and magnitude information for self correction was developed. The information also allows simultaneous support for parallel imaging for multiple coil acquisitions. Without a separate field map acquisition, a phase estimate from each echo in multiple echo train was generated. When using a multiple channel coil, magnitude and phase estimates from each echo provide in vivo coil sensitivities. An algorithm based on the conjugate gradient method uses these estimates to simultaneously remove phase inconsistencies between echoes, and in the case of multiple coil acquisition, simultaneously provides parallel imaging benefits. The algorithm is demonstrated on single channel, multiple channel, and undersampled data. Substantial image quality improvements were demonstrated. Signal dropouts were completely removed and undersampling artifacts were well suppressed. The suggested algorithm is able to remove phase cancellation and undersampling artifacts simultaneously and to improve image quality of multiecho radial imaging, the important technique for fast three-dimensional MRI data acquisition. Copyright © 2011 Wiley-Liss, Inc.

Effects of Gradient Coil Noise and Gradient Coil Replacement on the Reproducibility of Resting State Networks.

Science.gov (United States)

Bagarinao, Epifanio; Tsuzuki, Erina; Yoshida, Yukina; Ozawa, Yohei; Kuzuya, Maki; Otani, Takashi; Koyama, Shuji; Isoda, Haruo; Watanabe, Hirohisa; Maesawa, Satoshi; Naganawa, Shinji; Sobue, Gen

2018-01-01

The stability of the MRI scanner throughout a given study is critical in minimizing hardware-induced variability in the acquired imaging data set. However, MRI scanners do malfunction at times, which could generate image artifacts and would require the replacement of a major component such as its gradient coil. In this article, we examined the effect of low intensity, randomly occurring hardware-related noise due to a faulty gradient coil on brain morphometric measures derived from T1-weighted images and resting state networks (RSNs) constructed from resting state functional MRI. We also introduced a method to detect and minimize the effect of the noise associated with a faulty gradient coil. Finally, we assessed the reproducibility of these morphometric measures and RSNs before and after gradient coil replacement. Our results showed that gradient coil noise, even at relatively low intensities, could introduce a large number of voxels exhibiting spurious significant connectivity changes in several RSNs. However, censoring the affected volumes during the analysis could minimize, if not completely eliminate, these spurious connectivity changes and could lead to reproducible RSNs even after gradient coil replacement.

Critical current studies of a HTS rectangular coil

Energy Technology Data Exchange (ETDEWEB)

Zhong, Z. [Department of Engineering, University of Cambridge (United Kingdom); Chudy, M., E-mail: Michal.chudy@stuba.sk [Graduate School of Technology Management, University of Pretoria (South Africa); Institute of Power and Applied Electrical Engineering, Slovak University of Technology in Bratislava (Slovakia); Ruiz, H.S. [Department of Engineering, University of Leicester, Leicester LE1 7RH (United Kingdom); Zhang, X.; Coombs, T. [Department of Engineering, University of Cambridge (United Kingdom)

2017-05-15

Highlights: • Unique square pancake coil was manufactured. • Measurements in relatively high magnetic field were performed. • Different sections of the coil were characterized. • Parts of the coil which are limiting critical current were identified. - Abstract: Nowadays, superconducting high field magnets are used in numerous applications due to their superior properties. High temperature superconductors (HTS) are usually used for production of circular pancake or racetrack coils. However different geometries of HTS coils might be required for some specific applications. In this study, the HTS coil wound on a rectangular frame was fully characterized in homogeneous DC background field. The study contains measurements of critical current angular dependencies. The critical current of the entire coil and two selected strands under different magnitudes and orientations of external magnetic fields are measured. The critical regions of the coil in different angular regimes are determined. This study brings better understanding of the in- field performance of HTS coils wound on frames with right-angles.

Retrospective correction of bias in diffusion tensor imaging arising from coil combination mode.

Science.gov (United States)

Sakaie, Ken; Lowe, Mark

2017-04-01

To quantify and retrospectively correct for systematic differences in diffusion tensor imaging (DTI) measurements due to differences in coil combination mode. Multi-channel coils are now standard among MRI systems. There are several options for combining signal from multiple coils during image reconstruction, including sum-of-squares (SOS) and adaptive combine (AC). This contribution examines the bias between SOS- and AC-derived measures of tissue microstructure and a strategy for limiting that bias. Five healthy subjects were scanned under an institutional review board-approved protocol. Each set of raw image data was reconstructed twice-once with SOS and once with AC. The diffusion tensor was calculated from SOS- and AC-derived data by two algorithms-standard log-linear least squares and an approach that accounts for the impact of coil combination on signal statistics. Systematic differences between SOS and AC in terms of tissue microstructure (axial diffusivity, radial diffusivity, mean diffusivity and fractional anisotropy) were evaluated on a voxel-by-voxel basis. SOS-based tissue microstructure values are systematically lower than AC-based measures throughout the brain in each subject when using the standard tensor calculation method. The difference between SOS and AC can be virtually eliminated by taking into account the signal statistics associated with coil combination. The impact of coil combination mode on diffusion tensor-based measures of tissue microstructure is statistically significant but can be corrected retrospectively. The ability to do so is expected to facilitate pooling of data among imaging protocols. Copyright © 2016 Elsevier Inc. All rights reserved.

Embroidered Coils for Magnetic Resonance Sensors

Directory of Open Access Journals (Sweden)

Michael I. Newton

2013-04-01

Full Text Available Magnetic resonance imaging is a widely used technique for medical and materials imaging. Even though the objects being imaged are often irregularly shaped, suitable coils permitting the measurement of the radio-frequency signal in these systems are usually made of solid copper. One problem often encountered is how to ensure the coils are both in close proximity and conformal to the object being imaged. Whilst embroidered conductive threads have previously been used as antennae in mobile telecommunications applications, they have not previously been reported for use within magnetic resonance. In this paper we show that an embroidered single loop coil can be used in a commercial unilateral nuclear magnetic resonance system as an alternative to a solid copper. Data is presented showing the determination of both longitudinal (T1 and effective transverse (T2eff relaxation times for a flat fabric coil and the same coil conformed to an 8 cm diameter cylinder. We thereby demonstrate the principles required for the wider use of fabric based conformal coils within nuclear magnetic resonance and magnetic resonance imaging.

Open-Coil Retraction Spring

Directory of Open Access Journals (Sweden)

Pavankumar Janardan Vibhute

2011-01-01

Full Text Available Sliding mechanic has become a popular method for space closure with developments in preadjusted edgewise appliance. Furthermore, various space closing auxiliaries have been developed and evaluated extensively for their clinical efficiency. Their effectiveness enhanced with optimum force magnitude and low-load deflection rate (LDR/force decay. With the advent of NiTi springs in orthodontics, LDRs have been markedly reduced. For use of NiTi, clinician has to depend upon prefabricated closed coil springs. “Open Coil Retraction Spring (OCRS” is developed utilizing NiTi open-coil spring for orthodontic space closure. This paper describes fabrication and clinical application of OCRS which have number of advantages. It sustains low LDR with optimum force magnitude. Its design is adjustable for desired length and force level. It is fail-safe for both activation and deactivation (i.e., it cannot be over activated, and decompression limit of open coil is also controlled by the operator, resp.. A possibility to offset the OCRS away from mucosa helps to reduce its soft-tissue impingement.

RF safety assessment of a bilateral four-channel transmit/receive 7 Tesla breast coil: SAR versus tissue temperature limits.

Science.gov (United States)

Fiedler, Thomas M; Ladd, Mark E; Bitz, Andreas K

2017-01-01

The purpose of this work was to perform an RF safety evaluation for a bilateral four-channel transmit/receive breast coil and to determine the maximum permissible input power for which RF exposure of the subject stays within recommended limits. The safety evaluation was done based on SAR as well as on temperature simulations. In comparison to SAR, temperature is more directly correlated with tissue damage, which allows a more precise safety assessment. The temperature simulations were performed by applying three different blood perfusion models as well as two different ambient temperatures. The goal was to evaluate whether the SAR and temperature distributions correlate inside the human body and whether SAR or temperature is more conservative with respect to the limits specified by the IEC. A simulation model was constructed including coil housing and MR environment. Lumped elements and feed networks were modeled by a network co-simulation. The model was validated by comparison of S-parameters and B 1 + maps obtained in an anatomical phantom. Three numerical body models were generated based on 3 Tesla MRI images to conform to the coil housing. SAR calculations were performed and the maximal permissible input power was calculated based on IEC guidelines. Temperature simulations were performed based on the Pennes bioheat equation with the power absorption from the RF simulations as heat source. The blood perfusion was modeled as constant to reflect impaired patients as well as with a linear and exponential temperature-dependent increase to reflect two possible models for healthy subjects. Two ambient temperatures were considered to account for cooling effects from the environment. The simulation model was validated with a mean deviation of 3% between measurement and simulation results. The highest 10 g-averaged SAR was found in lung and muscle tissue on the right side of the upper torso. The maximum permissible input power was calculated to be 17 W. The

Progress on large superconducting toroidal field coils

International Nuclear Information System (INIS)

Haubenreich, P.N.; Luton, J.N.; Thompson, P.B.; Beard, D.S.

1979-01-01

Large superconducting toroidal field coils of competing designs are being produced by six major industrial teams. In the US, teams headed by General Dynamics Convair, General Electric, and Westinghouse are under contract to design and fabricate one coil each to specifications established by the Large Coil Program. A facility for testing 6 coils in a toroidal array at fields to 8 to 12 tesla is under construction at Oak Ridge. Through an international agreement, EURATOM, Japan, and Switzerland will produce one coil each for testing with the US coils. Each test coil will have a 2.5 x 3.5 m D-shape winding bore and is designed to operate at a current of 10 to 18 kA at a peak field of 8T while subjected to pulsed fields of 0.14 T applied in 1.0 s. There are significant differences among the six coil designs: five use NbTi, one Nb 3 Sn; three are cooled by pool boiling helium, three by forced flow; five have welded or bolted stainless steel coil cases, one has aluminum plate structure. All are designed to be cryostable at 8T, with structural margin for extended operation. The three US coil teams are almost or completely finished with detailed design and are now procuring materials and setting up manufacturing equipment. The non-US teams are at various stages of verification testing and design. The GDC and GE coils are scheduled for delivery in the spring of 1981 and the others will be completed a year later. The 11-m diameter vessel at the test facility has been completed and major components of the test stand are being procured. Engineering and procurement to upgrade the helium liquifier-refrigerator system are under way

Integrated B1+ Mapping for Hyperpolarized 13C MRI in a Clinical Setup using Multi-Channel Receive Arrays

DEFF Research Database (Denmark)

Hansen, Rie Beck; Shin, Peter J.; Gordon, Jeremy W.

inhomogeneous transmit coils, and because kinetic modeling based on incorrect flip angles can lead to incorrect rate constant estimations. This study demonstrates the feasibility of integrated B1+ mapping for large volume thermal and hyperpolarized phantoms in a clinical setup using a clamshell transmit coil...... and a 16-channel receive array, and a 3D stack-of-spirals sequence. Phase-sensitive coil-combination was achieved using ESPIRiT....

Startup of large coil test facility

International Nuclear Information System (INIS)

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. 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. (author)

Steering Electromagnetic Fields in MRI: Investigating Radiofrequency Field Interactions with Endogenous and External Dielectric Materials for Improved Coil Performance at High Field

Science.gov (United States)

Vaidya, Manushka

Although 1.5 and 3 Tesla (T) magnetic resonance (MR) systems remain the clinical standard, the number of 7 T MR systems has increased over the past decade because of the promise of higher signal-to-noise ratio (SNR), which can translate to images with higher resolution, improved image quality and faster acquisition times. However, there are a number of technical challenges that have prevented exploiting the full potential of ultra-high field (≥ 7 T) MR imaging (MRI), such as the inhomogeneous distribution of the radiofrequency (RF) electromagnetic field and specific energy absorption rate (SAR), which can compromise image quality and patient safety. To better understand the origin of these issues, we first investigated the dependence of the spatial distribution of the magnetic field associated with a surface RF coil on the operating frequency and electrical properties of the sample. Our results demonstrated that the asymmetries between the transmit (B1+) and receive (B 1-) circularly polarized components of the magnetic field, which are in part responsible for RF inhomogeneity, depend on the electric conductivity of the sample. On the other hand, when sample conductivity is low, a high relative permittivity can result in an inhomogeneous RF field distribution, due to significant constructive and destructive interference patterns between forward and reflected propagating magnetic field within the sample. We then investigated the use of high permittivity materials (HPMs) as a method to alter the field distribution and improve transmit and receive coil performance in MRI. We showed that HPM placed at a distance from an RF loop coil can passively shape the field within the sample. Our results showed improvement in transmit and receive sensitivity overlap, extension of coil field-of-view, and enhancement in transmit/receive efficiency. We demonstrated the utility of this concept by employing HPM to improve performance of an existing commercial head coil for the

Optimization of the ECT background coil

International Nuclear Information System (INIS)

Ballou, J.K.; Luton, J.N.

1975-01-01

This study was begun to optimize the Eccentric Coil Test (ECT) background coil. In the course of this work a general optimization code was obtained, tested, and applied to the ECT problem. So far this code has proven to be very satisfactory. The results obtained with this code and earlier codes have illustrated the parametric behavior of such a coil system and that the optimum for this type system is broad. This study also shows that a background coil with a winding current density of less than 3000 A/cm 2 is not feasible for the ECT models presented in this paper

Evaluation of feasibility of 1.5 Tesla prostate MRI using body coil RF transmit in a patient with an implanted vagus nerve stimulator.

Science.gov (United States)

Favazza, Christopher P; Edmonson, Heidi A; Ma, Chi; Shu, Yunhong; Felmlee, Joel P; Watson, Robert E; Gorny, Krzysztof R

2017-11-01

To assess risks of RF-heating of a vagus nerve stimulator (VNS) during 1.5 T prostate MRI using body coil transmit and to compare these risks with those associated with MRI head exams using a transmit/receive head coil. Spatial distributions of radio-frequency (RF) B1 fields generated by transmit/receive (T/R) body and head coils were empirically assessed along the long axis of a 1.5 T MRI scanner bore. Measurements were obtained along the center axis of the scanner and laterally offset by 15 cm (body coil) and 7 cm (head coil). RF-field measurements were supplemented with direct measurements of RF-heating of 15 cm long copper wires affixed to and submerged in the "neck" region of the gelled saline-filled (sodium chloride and polyacrylic acid) "head-and-torso" phantom. Temperature elevations at the lead tips were measured using fiber-optic thermometers with the phantom positioned at systematically increased distances from the scanner isocenter. B1 field measurements demonstrated greater than 10 dB reduction in RF power at distances beyond 28 cm and 24 cm from isocenter for body and head coil, respectively. Moreover, RF power from body coil transmit at distances greater than 32 cm from isocenter was found to be lower than from the RF power from head coil transmit measured at locations adjacent to the coil array at its opening. Correspondingly, maximum temperature elevations at the tips of the copper wires decreased with increasing distance from isocenter - from 7.4°C at 0 cm to no appreciable heating at locations beyond 40 cm. For the particular scanner model evaluated in this study, positioning an implanted VNS farther than 32 cm from isocenter (configuration achievable for prostate exams) can reduce risks of RF-heating resulting from the body coil transmit to those associated with using a T/R head coil. © 2017 American Association of Physicists in Medicine.

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

Science.gov (United States)

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.

Stress relaxation in SSC 50mm dipole coils

International Nuclear Information System (INIS)

Rogers, D.; Markley, F.

1992-04-01

We are measuring the stress relaxation of SSC 50mm outer coils with the goal of predicting how much of the coil prestress will be lost while the coils are warehoused between manufacture and cooldown. We manufacture 3 inch (76.2mm) long segments of coil with the same materials and techniques that have been used for prototype coils. We are running four simultaneous tests in an attempt to separate the contributions of the different coil materials. Test one is a completely insulated coil section where the insulation is the all polyamide system being tested at Brookhaven; test two is a wire stack insulated only with the normal Kapton overwrap; test three is a stack of bare cable; and test four is a completely insulated normal coil section. All, except for the bare cable, include the ground insulation. The insulated coil sections are carefully dried before loading and testing in order to eliminate stress changes due to varying moisture content. The temperature dependence of the stress relaxation is being studied separately. Three companion papers presented at this conference will be: (1) ''Temperature dependence of the viscoelastic properties of SSC coil insulation'' (2) ''Measurement of the elastic modulus of Kapton perpendicular to the plane of the film at room and cryogenic temperatures'' (3) ''Theoretical methods for creep and stress relaxation studies of SSC coil.''

Eccentric figure-eight coils for transcranial magnetic stimulation.

Science.gov (United States)

Sekino, Masaki; Ohsaki, Hiroyuki; Takiyama, Yoshihiro; Yamamoto, Keita; Matsuzaki, Taiga; Yasumuro, Yoshihiro; Nishikawa, Atsushi; Maruo, Tomoyuki; Hosomi, Koichi; Saitoh, Youichi

2015-01-01

Previously we proposed an eccentric figure-eight coil that can cause threshold stimulation in the brain at lower driving currents. In this study, we performed numerical simulations and magnetic stimulations to healthy subjects for evaluating the advantages of the eccentric coil. The simulations were performed using a simplified spherical brain model and a realistic human brain model. We found that the eccentric coil required a driving current intensity of approximately 18% less than that required by the concentric coil to cause comparable eddy current densities within the brain. The eddy current localization of the eccentric coil was slightly higher than that of the concentric coil. A prototype eccentric coil was designed and fabricated. Instead of winding a wire around a bobbin, we cut eccentric-spiral slits on the insulator cases, and a wire was woven through the slits. The coils were used to deliver magnetic stimulation to healthy subjects; among our results, we found that the current slew rate corresponding to motor threshold values for the concentric and eccentric coils were 86 and 78 A/µs, respectively. The results indicate that the eccentric coil consistently requires a lower driving current to reach the motor threshold than the concentric coil. Future development of compact magnetic stimulators will enable the treatment of some intractable neurological diseases at home. © 2014 Wiley Periodicals, Inc.

Value of the free light chain analysis in the clinical evaluation of response in multiple myeloma patients receiving anti-myeloma therapy

DEFF Research Database (Denmark)

Toftmann Hansen, Charlotte; Pedersen, Per T.; Jensen, Bo Amdi

Value of the free light chain analysis in the clinical evaluation of response in multiple myeloma patients receiving anti-myeloma therapy.......Value of the free light chain analysis in the clinical evaluation of response in multiple myeloma patients receiving anti-myeloma therapy....

Testing electrical insulation of LCT coils and instrumentation

International Nuclear Information System (INIS)

Luton, J.N.; Ulbricht, A.R.; Ellis, J.F.; Shen, S.S.; Wilson, C.T.; Okuno, K.; Siewerdt, L.O.; Zahn, G.R.; Zichy, J.A.

1986-09-01

Three of the superconducting test coils in the Large Coil Task (LCT) use conductors cooled internally by forced flow of helium. In the other three coils, the conductors are cooled externally by a bath of helium. The coils and facility are designed for rapid discharges (dumps) at voltages up to 2.5 kV, depending on coil design. Many coil sensors are connected electrically to the conductors. These sensor leads and signal conditioning equipment also experience high voltage. High-potential tests of ground insulation were performed on all components of the International Fusion Superconducting Magnet Test Facility (IFSMTF). Coil insulation was also tested by ring-down tests that produced voltage distributions within the coils like those occurring during rapid discharge. Methods were developed to localize problem areas and to eliminate them. The effect on breakdown voltage near the Paschen minimum of magnetic fields up to 2 T was investigated

Split Coil Forms for Rotary Transformers

Science.gov (United States)

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.

Design and Fabrication of the KSTAR Poloidal Field Coil Structure

International Nuclear Information System (INIS)

Park, H. K.; Choi, C. H.; Sa, J. W.

2005-01-01

The KSTAR magnet system consists of 16 toroidal field(TF) coils. 4 pairs of central solenoid(CS) coils, and 3 pairs of outer poloidal field(PF) coils. The TF coils are encased in a structure to enhance mechanical stability. The CS coil structure is supported on top of the TF coil structure and supplies a vertical compression of 15 MN to prevent lateral movement due to a repulsive force between the CS coils. The PF coil system is vertically symmetry to the machine mid-plane and consists of 6 coils and 80 support structures(i.e, 16 for PF5, 32 for PF6 and 32 fort PF7). All PF coil structures should absorb the thermal contraction difference between TF coil structure and PF coils due to cool down and endure the vertical and radial magnetic forces due to current charging. In order to satisfy these structural requirements. the PF5 coil structure is designed base on hinges and both of PF6 and PF7 coil structures based on flexible plates. The PF coil structures are assembled on the TF coil structure with an individual basement that is welded on the TF coil structure

Characteristics of parallel reverse coil inductors with different current ratio in coils used for melting in a suspension state

International Nuclear Information System (INIS)

Fogel', A.A.; Sidorova, T.A.; Smirnov, V.V.; Mezdrogina, M.M.

1975-01-01

The paper studies the effect of the ratio of the currents in the coils of an inductor with a parallel-switched ''reverse coil'', where the ratio of the current in the upper coil to that in the lower coil is 0.72. A region of stable dependence of liquid niobium characterized by upper and lower limits has been found. The maximum permissible volume of liquid niobium increases as the ratio of current in the upper coil to current in the lower coil decreases. The temperature dependences of niobium on the voltage in the inductor have been derived. Experiments have shown that the greater the capillary constant of niobium, the larger the region of stable dependence of liquid niobium, the larger the range of possible temperature regulation and the larger the maximum permissible volume. (N.K.)

Extrap with iron-cored coils

International Nuclear Information System (INIS)

Lehnert, B.

1985-05-01

In Extrap configurations there is a high average beta value with respect to the plasma confinement volume. The externally imposed magnetic field which is required for stabilization therefore comes out to have a rather moderate strength, even under expected reactor conditions. As a consequence, this field can be generated not only by conventional external conductor arrangements, but also by iron-cored coils being operated below the saturation limit. A proposal for such iron-cored coil systems is presented in this paper. As compared to conventional conductors, this has the advantage of localizing the magnetic energy of the externally imposed magnetic field mainly to the discharge vessel and the plasma volume, thereby increasing the engineering beta value substantially. Also the problems of the coil stresses and of irradiation of the coils appear to become simplified, as well as replacement of the coil system. A main limitation of this proposal is due to combination of iron core saturation with the required stabilization effect from an ion Larmor radius of sufficient relative magnitude. This limitaion requires further investigation, especially in the full-scale reactor case. Also the modifications of the field geometry by iron core shaping needs further analysis. (Author)

Novel transcranial magnetic stimulation coil for mice

Science.gov (United States)

March, Stephen; Stark, Spencer; Crowther, Lawrence; Hadimani, Ravi; Jiles, David

2014-03-01

Transcranial magnetic stimulation (TMS) shows potential for non-invasive treatment of various neurological disorders. Significant work has been performed on the design of coils used for TMS on human subjects but few reports have been made on the design of coils for use on the brains of animals such as mice. This work is needed as TMS studies utilizing mice can allow rapid preclinical development of TMS for human disorders but the coil designs developed for use on humans are inadequate for optimal stimulation of the much smaller mouse brain. A novel TMS coil has been developed with the goal of inducing strong and focused electric fields for the stimulation of small animals such as mice. Calculations of induced electric fields were performed utilizing an MRI derived inhomogeneous model of an adult male mouse. Mechanical and thermal analysis of this new TMS helmet-coil design have also been performed at anticipated TMS operating conditions to ensure mechanical stability of the new coil and establish expected linear attraction and rotational force values. Calculated temperature increases for typical stimulation periods indicate the helmet-coil system is capable of operating within established medical standards. A prototype of the coil has been fabricated and characterization results are presented.

Characteristics of bowl-shaped coils for transcranial magnetic stimulation

Science.gov (United States)

Yamamoto, Keita; Suyama, Momoko; Takiyama, Yoshihiro; Kim, Dongmin; Saitoh, Youichi; Sekino, Masaki

2015-05-01

Transcranial magnetic stimulation (TMS) has recently been used as a method for the treatment of neurological and psychiatric diseases. Daily TMS sessions can provide continuous therapeutic effectiveness, and the installation of TMS systems at patients' homes has been proposed. A figure-eight coil, which is normally used for TMS therapy, induces a highly localized electric field; however, it is challenging to achieve accurate coil positioning above the targeted brain area using this coil. In this paper, a bowl-shaped coil for stimulating a localized but wider area of the brain is proposed. The coil's electromagnetic characteristics were analyzed using finite element methods, and the analysis showed that the bowl-shaped coil induced electric fields in a wider area of the brain model than a figure-eight coil. The expanded distribution of the electric field led to greater robustness of the coil to the coil-positioning error. To improve the efficiency of the coil, the relationship between individual coil design parameters and the resulting coil characteristics was numerically analyzed. It was concluded that lengthening the outer spherical radius and narrowing the width of the coil were effective methods for obtaining a more effective and more uniform distribution of the electric field.

Stress distributions of coils for toroidal magnetic field

International Nuclear Information System (INIS)

Kajita, Tateo; Miyamoto, Kenro.

1976-01-01

The stress distributions of a D shaped coil and a circular coil are computed by the finite element method. The dependences of the stress distribution on the geometrical parameters of the stress distribution on the geometrical parameters of the coils and supporting methods are examined. The maximum amount of the stress in the D shaped coil is not much smaller than that of the circular one. However, the stress distribution of the D shaped coil becomes much more uniform. The supporting method has as much effect as the geometrical parameters of the coil on the stress distribution. (auth.)

d-Cysteine Ligands Control Metal Geometries within De Novo Designed Three-Stranded Coiled Coils

DEFF Research Database (Denmark)

Ruckthong, Leela; Peacock, Anna F.A.; Pascoe, Cherilyn E.

2017-01-01

Although metal ion binding to naturally occurring l-amino acid proteins is well documented, understanding the impact of the opposite chirality (d-)amino acids on the structure and stereochemistry of metals is in its infancy. We examine the effect of a d-configuration cysteine within a designed l......-amino acid three-stranded coiled coil in order to enforce a precise coordination number on a metal center. The d chirality does not alter the native fold, but the side-chain re-orientation modifies the sterics of the metal binding pocket. l-Cys side chains within the coiled-coil structure have previously...... by comparison of the structure of ZnIICl(CSL16DC)3 2- to the published structure of ZnII(H2O)(GRAND-CSL12AL16LC)3 -. Moreover, spectroscopic analysis indicates that the CdII geometry observed by using l-Cys ligands (a mixture of three- and four-coordinate CdII) is altered to a single four-coordinate species...

Structure and Misfolding of the Flexible Tripartite Coiled-Coil Domain of Glaucoma-Associated Myocilin

Energy Technology Data Exchange (ETDEWEB)

Hill, Shannon E.; Nguyen, Elaine; Donegan, Rebecca K.; Patterson-Orazem, Athéna C.; Hazel, Anthony; Gumbart, James C.; Lieberman, Raquel L.

2017-11-01

Glaucoma-associated myocilin is a member of the olfactomedins, a protein family involved in neuronal development and human diseases. Molecular studies of the myocilin N-terminal coiled coil demonstrate a unique tripartite architecture: a Y-shaped parallel dimer-of-dimers with distinct tetramer and dimer regions. The structure of the dimeric C-terminal 7-heptad repeats elucidates an unexpected repeat pattern involving inter-strand stabilization by oppositely charged residues. Molecular dynamics simulations reveal an alternate accessible conformation in which the terminal inter-strand disulfide limits the extent of unfolding and results in a kinked configuration. By inference, full-length myocilin is also branched, with two pairs of C-terminal olfactomedin domains. Selected variants within the N-terminal region alter the apparent quaternary structure of myocilin but do so without compromising stability or causing aggregation. In addition to increasing our structural knowledge of naturally occurring extracellular coiled coils and biomedically important olfactomedins, this work broadens the scope of protein misfolding in the pathogenesis of myocilin-associated glaucoma.

Transcranial Magnetic Stimulation-coil design with improved focality

Science.gov (United States)

Rastogi, P.; Lee, E. G.; Hadimani, R. L.; Jiles, D. C.

2017-05-01

Transcranial Magnetic Stimulation (TMS) is a technique for neuromodulation that can be used as a non-invasive therapy for various neurological disorders. In TMS, a time varying magnetic field generated from an electromagnetic coil placed on the scalp is used to induce an electric field inside the brain. TMS coil geometry plays an important role in determining the focality and depth of penetration of the induced electric field responsible for stimulation. Clinicians and basic scientists are interested in stimulating a localized area of the brain, while minimizing the stimulation of surrounding neural networks. In this paper, a novel coil has been proposed, namely Quadruple Butterfly Coil (QBC) with an improved focality over the commercial Figure-8 coil. Finite element simulations were conducted with both the QBC and the conventional Figure-8 coil. The two coil's stimulation profiles were assessed with 50 anatomically realistic MRI derived head models. The coils were positioned on the vertex and the scalp over the dorsolateral prefrontal cortex to stimulate the brain. Computer modeling of the coils has been done to determine the parameters of interest-volume of stimulation, maximum electric field, location of maximum electric field and area of stimulation across all 50 head models for both coils.

Manufacturing development of the Westinghouse Nb3Sn coil for the Large Coil Test Program

International Nuclear Information System (INIS)

Young, J.L.; Vota, T.L.; Singh, S.K.

1983-01-01

The Westinghouse Nb 3 Sn Magnet for the Oak Ridge National Laboratory Large Coil Program (LCP) is currently well into the manufacturing phase. This paper identifies the manufacturing processes and development tasks for his unique, advanced coil

Superconductive magnet having shim coils and quench protection circuits

International Nuclear Information System (INIS)

Schwall, R.E.

1987-01-01

A superconductive magnet is described comprising: a first persistent current loop comprising a first superconductor and a main coil connected to the first superconductor, the main coil being operative in response to superconduction therein to generate a primary magnetic field; a second persistent current loop comprising a second superconductor and a shim coil connected thereto, the shim coil being operative in response to superconduction therein to generate a corrective field for correcting aberrations in a predetermined gradient in the primary magnetic field, the shim coil having fewer turns than the main coil and being inductively coupled therewith whereby small changes in the current in the main coil cause much greater changes in the current in the shim coil. The magnet is characterized by an improvement which consists of: a first heater connected across the second persistent loop in parallel with the shim coil, the first heater being normally inoperative to carry current while the shim coil and the second superconductor are superconducting, the first heater being operative in response to current therein to heat the shim coil to a resistive state; and protective circuit means comprising a second heater connected to the main coil for carrying current from the main coil upon quenching of the main coil, the second heater being disposed in thermal contact with the second superconductor to heat the second superconductor to a resistive state in response to the current from the main coil to thereby divert current in the second persistent loop through the second heater causing it to heat the shim coil to a resistive state and resistively dissipate energy therein

Three-layered radio frequency coil arrangement for sodium MRI of the human brain at 9.4 Tesla.

Science.gov (United States)

Shajan, G; Mirkes, Christian; Buckenmaier, Kai; Hoffmann, Jens; Pohmann, Rolf; Scheffler, Klaus

2016-02-01

A multinuclei imaging setup with the capability to acquire both sodium ((23) Na) and proton ((1) H) signals at 9.4 Tesla is presented. The main objective was to optimize coil performance at the (23) Na frequency while still having the ability to acquire satisfactory (1) H images. The setup consisted of a combination of three radio frequency (RF) coils arranged in three layers: the innermost layer was a 27-channel (23) Na receive helmet which was surrounded by a four-channel (23) Na transceiver array. The outer layer consisted of a four-channel (1) H dipole array for B0 shimming and anatomical localization. Transmit and receive performance of the (23) Na arrays was compared to a single-tuned (23) Na birdcage resonator. While the transmit efficiency of the (23) Na transceiver array was comparable to the birdcage, the (23) Na receive array provided substantial signal-to-noise ratio (SNR) gain near the surface and comparable SNR in the center. The utility of this customized setup was demonstrated by (23) Na images of excellent quality. High SNR, efficient transmit excitation and B0 shimming capability can be achieved for (23) Na MRI at 9.4T using novel coil combination. This RF configuration is easily adaptable to other multinuclei applications at ultra high field (≥ 7T). © 2015 Wiley Periodicals, Inc.

Optimal power allocation of a single transmitter-multiple receivers channel in a cognitive sensor network

KAUST Repository

Ayala Solares, Jose Roberto; Rezki, Zouheir; Alouini, Mohamed-Slim

2012-01-01

The optimal transmit power of a wireless sensor network with one transmitter and multiple receivers in a cognitive radio environment while satisfying independent peak, independent average, sum of peak and sum of average transmission rate constraints

An Air Bearing Rotating Coil Magnetic Measurement System

CERN Document Server

Gottschalk, Stephen C; Taylor, David J; Thayer, William

2005-01-01

This paper describes a rotating coil magnetic measurement system supported on air bearings. The design is optimized for measurements of 0.1micron magnetic centerline changes on long, small aperture quadrupoles. Graphite impregnated epoxy resin is used for the coil holder and coil winding forms. Coil holder diameter is 11 mm with a length between supports of 750mm. A pair of coils is used to permit quadrupole bucking during centerline measurements. Coil length is 616mm, inner radius 1.82mm, outer radius 4.74mm. The key features of the mechanical system are simplicity; air bearings for accurate, repeatable measurements without needing warm up time and a vibration isolated stand that uses a steel-topped Newport optical table with air suspension. Coil rotation is achieved by a low noise servo motor controlled by a standalone Ethernet servo board running custom servo software. Coil calibration procedures that correct wire placement errors, tests for mechanical resonances, and other system checks will also be discu...

Anisotropic metamaterial for efficiency enhancement of mid-range wireless power transfer under coil misalignment

International Nuclear Information System (INIS)

Ranaweera, A L A K; Moscoso, Carlos Arriola; Lee, Jong-Wook

2015-01-01

In a wireless power transfer (WPT) system, misalignment between transmitter and receiver coils is one of the key factors affecting efficiency. Recently, metamaterials have shown great potential to enhance electromagnetic propagation in various environments. In this work, we apply a metamaterial to enhance the WPT in a more general environment where misalignment is considered. Using an anisotropic metamaterial, we obtain a significant efficiency enhancement. Therefore, we propose that the metamaterial is an effective means to mitigate the decreased efficiency caused by misalignment. In addition, we investigate the effect of coil misalignment on the threshold distance beyond which the metamaterial enhances the performance of WPT. (paper)

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

Energy Technology Data Exchange (ETDEWEB)

Andreas, Michael P.; Ajay, Gautam; Gellings, Jaclyn A.; Rayment, Ivan (UW)

2017-12-01

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.

Quench detection system of the EURATOM coil for the Large Coil Task

International Nuclear Information System (INIS)

Noether, G.; Gauss, S.; Maurer, W.; Siewerdt, L.; Ulbricht, A.; Wuechner, F.

1989-01-01

A special quench detection system has been developed for the EURATOM Large Coil Task (LCT) coil. The system is based on a bridge circuit which uses a special 'two in hand' winding technique for the pancakes of the EURATOM LCT coil. The electronic circuit was designed in a fail safe way to prevent failure of the quench detector due to failure of one of its components. A method for quick balancing of the quench detection system in a large toroidal magnet system was applied. The quench detection system worked very reliably during the experimental phase of the LCT and was within the quench detection level setting of 50 mV, i.e. the system was not sensitive to poloidal field transients at or below this level. Non-electrical methods for quench detection were also investigated. (author)

Kilotesla Magnetic Field due to a Capacitor-Coil Target Driven by High Power Laser

Science.gov (United States)

Fujioka, Shinsuke; Zhang, Zhe; Ishihara, Kazuhiro; Shigemori, Keisuke; Hironaka, Youichiro; Johzaki, Tomoyuki; Sunahara, Atsushi; Yamamoto, Naoji; Nakashima, Hideki; Watanabe, Tsuguhiro; Shiraga, Hiroyuki; Nishimura, Hiroaki; Azechi, Hiroshi

2013-01-01

Laboratory generation of strong magnetic fields opens new frontiers in plasma and beam physics, astro- and solar-physics, materials science, and atomic and molecular physics. Although kilotesla magnetic fields have already been produced by magnetic flux compression using an imploding metal tube or plasma shell, accessibility at multiple points and better controlled shapes of the field are desirable. Here we have generated kilotesla magnetic fields using a capacitor-coil target, in which two nickel disks are connected by a U-turn coil. A magnetic flux density of 1.5 kT was measured using the Faraday effect 650 μm away from the coil, when the capacitor was driven by two beams from the GEKKO-XII laser (at 1 kJ (total), 1.3 ns, 0.53 or 1 μm, and 5 × 1016 W/cm2). PMID:23378905

Switching transients in a superconducting coil

International Nuclear Information System (INIS)

Owen, E.W.; Shimer, D.W.

1983-01-01

A study is made of the transients caused by the fast dump of large superconducting coils. Theoretical analysis, computer simulation, and actual measurements are used. Theoretical analysis can only be applied to the simplest of models. In the computer simulations two models are used, one in which the coil is divided into ten segments and another in which a single coil is employed. The circuit breaker that interrupts the current to the power supply, causing a fast dump, is represented by a time and current dependent conductance. Actual measurements are limited to measurements made incidental to performance tests on the MFTF Yin-yang coils. It is found that the breaker opening time is the critical factor in determining the size and shape of the transient. Instantaneous opening of the breaker causes a lightly damped transient with large amplitude voltages to ground. Increasing the opening time causes the transient to become a monopulse of decreasing amplitude. The voltages at the external terminals are determined by the parameters of the external circuit. For fast opening times the frequency depends on the dump resistor inductance, the circuit capacitance, and the amplitude on the coil current. For slower openings the dump resistor inductance and the current determine the amplitude of the voltage to ground at the terminals. Voltages to ground are less in the interior of the coil, where transients related to the parameters of the coil itself are observed

A TMS coil positioning/holding system for MR image-guided TMS interleaved with fMRI.

Science.gov (United States)

Bohning, Daryl E; Denslow, S; Bohning, P A; Walker, J A; George, M S

2003-11-01

Transcranial magnetic stimulation (TMS) can be interleaved with fMRI to visualize regional brain activity in response to direct, non-invasive, cortical stimulation, making it a promising tool for studying brain function. A major practical difficulty is accurately positioning the TMS coil within the MRI scanner for stimulating a particular area of brain cortex. The objective of this work was to design and build a self-contained hardware/software system for MR-guided TMS coil positioning in interleaved TMS/fMRI studies. A compact, manually operated, articulated TMS coil positioner/holder with 6 calibrated degrees of freedom was developed for use inside a cylindrical RF head coil, along with a software package for transforming between MR image coordinates, MR scanner space coordinates, and positioner/holder settings. Phantom calibration studies gave an accuracy for positioning within setups of dx=+/-1.9 mm, dy=+/-1.4 mm, dz=+/-0.8 mm and a precision for multiple setups of dx=+/-0.8 mm, dy=+/-0.1 mm, dz=+/-0.1 mm. This self-contained, integrated MR-guided TMS system for interleaved TMS/fMRI studies provides fast, accurate location of motor cortex stimulation sites traditionally located functionally, and a means of consistent, anatomy-based TMS coil positioning for stimulation of brain areas without overt response.

Resistive demountable toroidal-field coils for tokamak reactors

International Nuclear Information System (INIS)

Jassby, D.L.; Jacobsen, R.A.; Kalnavarns, J.; Masson, L.S.; Sekot, J.P.

1981-07-01

Readily demountable TF (toroidal-field) coils allow complete access to the internal components of a tokamak reactor for maintenance of replacement. The requirement of readily demountable joints dictates the use of water-cooled resistive coils, which have a host of decisive advantages over superconducting coils. Previous papers have shown that resistive TF coils for tokamak reactors can operate in the steady state with acceptable power dissipation (typically, 175 to 300 MW). This paper summarizes results of parametric studies of size optimization of rectangular TF coils and of a finite-element stress analysis, and examines several candidate methods of implementing demountable joints for rectangular coils constructed of plate segments

Manufacture of EAST VS In-Vessel Coil

International Nuclear Information System (INIS)

Long, Feng; Wu, Yu; Du, Shijun; Jin, Huan; Yu, Min; Han, Qiyang; Wan, Jiansheng; Liu, Bin; Qiao, Jingchun; Liu, Xiaochuan; Li, Chang; Cai, Denggang; Tong, Yunhua

2013-01-01

Highlights: • ITER like Stainless Steel Mineral Insulation Conductor (SSMIC) used for EAST Tokamak VS In-Vessel Coil manufacture first time. • Research on SSMIC fabrication was introduced in detail. • Two sets totally four single-turn VS coils were manufactured and installed in place symmetrically above and below the mid-plane in the vacuum vessel of EAST. • The manufacture and inspection of the EAST VS coil especially the joint for the SSMIC connection was described in detail. • The insulation resistances of all the VS coils have no significant reduction after endurance test. -- Abstract: In the ongoing latest update round of EAST (Experimental Advanced Superconducting Tokamak), two sets of two single-turn Vertical Stabilization (VS) coils were manufactured and installed symmetrically above and below the mid-plane in the vacuum vessel of EAST. The Stainless Steel Mineral Insulated Conductor (SSMIC) developed for ITER In-Vessel Coils (IVCs) in Institute of Plasma Physics, Chinese Academy of Science (ASIPP) was used for the EAST VS coils manufacture. Each turn poloidal field VS coil includes three internal joints in the vacuum vessel. The middle joint connects two pieces of conductor which together form an R2.3 m arc segment inside the vacuum vessel. The other two joints connect the arc segment with the two feeders near the port along the toroidal direction to bear lower electromagnetic loads during operation. Main processes and tests include material performances checking, conductor fabrication, joint connection and testing, coil forming, insulation performances measurement were described herein

Superconducting coil design for a tokamak experimental power reactor

International Nuclear Information System (INIS)

Turner, L.R.; Wang, S.T.; Smelser, P.

1977-01-01

Superconducting toroidal field (TF) and polodial-field (PF) coils have been designed for the proposed Argonne National Laboratory experimental power reactor (EPR). Features of the design include: (1) Peak field of 8 T at 4.2 K or 10 T at 3.0 K. (2) Constant-tension shape for the TF coils, corrected for the finite number (16) of coils. (3) Analysis of errors in coil alignment. (4) Comparison of safety aspects of series-connected and parallel-connected coils. (5) A 60 kA sheet conductor of NbTi with copper stabilizer and stainless steel for support. (6) Superconducting PF coils outside the TF coils. (7) The TF coils shielded from pulsed fields by high-purity aluminum

Normal zone detectors for a large number of inductively coupled coils

International Nuclear Information System (INIS)

Owen, E.W.; Shimer, D.W.

1983-01-01

In order to protect a set of inductively coupled superconducting magnets, it is necessary to locate and measure normal zone voltages that are small compared with the mutual and self-induced voltages. The method described in this paper uses two sets of voltage measurements to locate and measure one or more normal zones in any number of coupled coils. One set of voltages is the outputs of bridges that balance out the self-induced voltages. The other set of voltages can be the voltages across the coils, although alternatives are possible. The two sets of equations form a single combined set of equations. Each normal zone location or combination of normal zones has a set of these combined equations associated with it. It is demonstrated that the normal zone can be located and the correct set chosen, allowing determination of the size of the normal zone. Only a few operations take place in a working detector: multiplication of a constant, addition, and simple decision-making. In many cases the detector for each coil, although weakly linked to the other detectors, can be considered to be independent

Correcting coils in end magnets of accelerators

Directory of Open Access Journals (Sweden)

L. R. P. Kassab

1998-05-01

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

Quench simulation of SMES consisting of some superconducting coils

International Nuclear Information System (INIS)

Noguchi, S.; Oga, Y.; Igarashi, H.

2011-01-01

A chain of quenches may be caused by a quench of one element coil when SMES is consists of many element coils. To avoid the chain of quenches, the energy stored in element coil has to be quickly discharged. The cause of the chain of the quenches is the short time constant of the decreasing current of the quenched coil. In recent years, many HTS superconducting magnetic energy storage (HTS-SMES) systems are investigated and designed. They usually consist of some superconducting element coils due to storing excessively high energy. If one of them was quenched, the storage energy of the superconducting element coil quenched has to be immediately dispersed to protect the HTS-SMES system. As the result, the current of the other element coils, which do not reach to quench, increases since the magnetic coupling between the quenched element coil and the others are excessively strong. The increase of the current may cause the quench of the other element coils. If the energy dispersion of the element coil quenched was failed, the other superconducting element coil would be quenched in series. Therefore, it is necessary to investigate the behavior of the HTS-SMES after quenching one or more element coils. To protect a chain of quenches, it is also important to investigate the time constant of the coils. We have developed a simulation code to investigate the behavior of the HTS-SMES. By the quench simulation, it is indicated that a chain of quenches is caused by a quench of one element coil.

Design and modelling of a SMES coil

Energy Technology Data Exchange (ETDEWEB)

Yuan Weijia; Campbell, A M; Coombs, T A, E-mail: wy215@cam.ac.u [EPEC Superconductivity group, Engineering Department, 9 JJ Thomson Avenue, Cambridge, CB3 0FA (United Kingdom)

2010-06-01

The design of a Superconducting Magnetic Energy Storage (SMES) coil wound by coated conductors has been presented. Based on an existing model for coated conductor pancake coils, this paper analysed the magnetic field and current density distribution of the coil at two different operation temperatures, 77K and 22K. A comparison table of the critical currents and AC losses at these two temperatures has been presented. Several steps to improve the transport current of the coil have been suggested as well.

Coils in a fusion device and its fabrication method

International Nuclear Information System (INIS)

Maeda, Hideto; Moritani, Einoshin.

1975-01-01

Object: To provide a coil for nuclear fusion equipment, which coil has superior rigidity and strength and is separable into two sections and used for removing impurity ions from high temperature plasma such as heavy hydrogen and tritium. Structure: The coil according to the invention is manufactured by (1) a step of insulating horseshoe-shaped conductors one from another and bundling them into coil halves. (2) a step of assembling a flange on a coil case accommodating each coil half and hermetically welding a lid to each end of the coil half, (3) a step of evacuating the interior of each coil case, (4) a step of pouring a thermosetting resin into each evacuated coil case and hardening the resin, (5) a step of connecting the two coil halves with their ends not covered with resin held in abutting relation to each other, (6) a step of coupling coil case joint pieces to the joined portions and covering the joint pieces with a seal box and hermetically welding the box to the joint pieces, and (7) a step of pouring a thermosetting resin into each evacuated joint portion and hardening the resin. (Kamimura, M.)

MRI surface-coil pair with strong inductive coupling.

Science.gov (United States)

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.

Low-Noise Active Decoupling Circuit and its Application to 13C Cryogenic RF Coils at 3T

DEFF Research Database (Denmark)

Sanchez, Juan Diego; Søvsø Szocska Hansen, Esben; Laustsen, Christoffer

2017-01-01

We analyze the loss contributions in a small, 50-mm-diameter receive-only coil for carbon-13 (13C) magnetic resonance imaging at 3 T for 3 different circuits, which, including active decoupling, are compared in terms of their Q-factors and signal-to-noise ratio (SNR). The results show that a circ......We analyze the loss contributions in a small, 50-mm-diameter receive-only coil for carbon-13 (13C) magnetic resonance imaging at 3 T for 3 different circuits, which, including active decoupling, are compared in terms of their Q-factors and signal-to-noise ratio (SNR). The results show...... that a circuit using unsegmented tuning and split matching capacitors can provide 20% SNR enhancement at room temperature compared with that using more traditional designs. The performance of the proposed circuit was also measured when cryogenically cooled to 105 K, and an additional 1.6-fold SNR enhancement...... was achieved on a phantom. The enhanced circuit performance is based on the low capacitance needed to match to 50 when coil losses are low, which significantly reduces the proportion of the current flowing through the matching network and therefore minimizes this loss contribution. This effect makes...

Coil Migration after Transarterial Coil Embolization of a Splenic Artery Pseudoaneurysm

Directory of Open Access Journals (Sweden)

Bezawit D. Tekola

2013-11-01

Full Text Available A 48-year-old man with a history of splenic artery pseudoaneurysm requiring transarterial embolization 3 months earlier presented to the emergency department with abdominal pain and fever. Computed tomography showed evidence of embolization coil fragments within the gastrointestinal tract. Upper endoscopy showed a large gastric ulcer with numerous embolization coils extruding into the gastric lumen. The patient underwent partial gastrectomy, distal pancreatectomy and resection of the splenic artery pseudoaneurysm. This case illustrates a rare delayed complication of transarterial embolization of a splenic artery pseudoaneurysm.

First assembly phase for the ATLAS toroid coils

CERN Document Server

Patrice Loïez

2003-01-01

The ATLAS barrel toroid system consists of eight coils, each of axial length 25.3 m, assembled radially and symmetrically around the beam axis. The coils are of a flat racetrack type with two double-pancake windings made of 20.5 kA aluminium-stabilized niobium-titanium superconductor. In the first phase of assembly, the two 'pancakes' are packed into their vacuum vessel. This is done using bladders filled with resin and glass microbeads under pressure. The resin is heated and, once cooled, holds the pancakes in place. The operation has to be performed on both sides of the coil, which necessitated a special technique to turn the coils over and then transport them to the heating table. Photos 01, 02, 03: Use of the overhead travelling crane to hoist the coil up and then tilt it over, the coil frame's metal feet being used as rotational pivots, supporting half the coil's weight. Once it has been turned over, the coil, now with only half the frame, is transported to the heating table using a special lifting gant...

Second Barrel Toroid Coil Installed in ATLAS Cavern

CERN Multimedia

Tappern, G.

The second barrel toroid coil was lowered into the ATLAS Cavern on Friday, 26 November. The operation takes approximately five hours of precision crane and winch operations. Before lowering, several checks are made to ensure that no loose items have been left on the coil which would fall during the lowering down the shaft. This is a very difficult, but very important check, with the first coil in position, and partly below the shaft. After changing the winch tooling on Wednesday December 1st, the coil was lifted, rotated and placed into the feet. The girders which support the coil and the Z direction stops had all been pre-set before putting the coil in the feet. The angle is controlled by an inclinometer. When the final adjustments of position have been made, which will locate the coils at the plus/minus two mm level, the connection beams (voussoirs and struts) will be put in place; this requires a complex shimming procedure. This will lock together the two coils into the feet and forms the foundation for th...

Study on Pole Arrangement of the CEDM Coils

International Nuclear Information System (INIS)

Park, Jin Seok; Lee, Myoung Goo; Kim, Hyun Min; Cho, Yeon Ho; Choi, Taek Sang

2013-01-01

The coil stack assembly is important for reliable operation of the CEDM, there have been efforts to improve the design by optimizing the design parameters such as dimensions and winding turns. However, magnetic forces of the CEDM can also change by different pole arrangement even if their design parameters are the same. Since the latch coil and lift coil are installed connected to each other, they produce magnetically coupled field when they are energized at the same time. This coupling field can affect the magnetic force of the CEDM significantly. In this paper, coil pole arrangement effects are studied. Electro-magnetic analysis is performed for the different pole arrangements of the CEDM coils to calculate the magnetic forces. Pole arrangement effects on magnetic forces were studied by static analysis of the CEDM magnetic field. Magnetic forces were calculated and compared for the two different pole arrangements of the coils. The results show that the magnetic poles of the lift coil and latch coil shall be arranged to have the same magnetic pole direction to achieve higher magnetic force

Mechanical design of a high field common coil magnet

CERN Document Server

Caspi, S; Dietderich, D R; Gourlay, S A; Gupta, R; McInturff, A; Millos, G; Scanlan, R M

1999-01-01

A common coil design for high field 2-in-1 accelerator magnets has been previously presented as a "conductor-friendly" option for high field magnets applicable for a Very Large Hadron Collider. This paper presents the mechanical design for a 14 tesla 2-in-1 dipole based on the common coil design approach. The magnet will use a high current density Nb/sub 3/Sn conductor. The design addresses mechanical issues particular to the common coil geometry: horizontal support against coil edges, vertical preload on coil faces, end loading and support, and coil stresses and strains. The magnet is the second in a series of racetrack coil magnets that will provide experimental verification of the common coil design approach. (9 refs).

Low resolution crystal structure of Arenicola erythrocruorin: influence of coiled coils on the architecture of a megadalton respiratory protein.

Science.gov (United States)

Royer, William E; Omartian, Michael N; Knapp, James E

2007-01-05

Annelid erythrocruorins are extracellular respiratory complexes assembled from 180 subunits into hexagonal bilayers. Cryo-electron microscopic experiments have identified two different architectural classes. In one, designated type I, the vertices of the two hexagonal layers are partially staggered, with one hexagonal layer rotated by about 16 degrees relative to the other layer, whereas in the other class, termed type II, the vertices are essentially eclipsed. We report here the first crystal structure of a type II erythrocruorin, that from Arenicola marina, at 6.2 A resolution. The structure reveals the presence of long continuous triple-stranded coiled-coil "spokes" projecting towards the molecular center from each one-twelfth unit; interdigitation of these spokes provides the only contacts between the two hexagonal layers of the complex. This arrangement contrasts with that of a type I erythrocruorin from Lumbricus terrestris in which the spokes are broken into two triple-stranded coiled coils with a disjointed connection. The disjointed connection allows formation of a more compact structure in the type I architecture, with the two hexagonal layers closer together and additional extensive contacts between the layers. Comparison of sequences of the coiled-coil regions of various linker subunits shows that the linker subunits from type II erythrocruorins possess continuous heptad repeats, whereas a sequence gap places these repeats out of register in the type I linker subunits, consistent with a disjointed coiled-coil arrangement.

SSC [Superconducting Super Collider] dipole coil production tooling

International Nuclear Information System (INIS)

Carson, J.A.; Barczak, E.J.; Bossert, R.C.; Brandt, J.S.; Smith, G.A.

1989-03-01

Superconducting Super Collider dipole coils must be produced to high precision to ensure uniform prestress and even conductor distribution within the collared coil assembly. Tooling is being prepared at Fermilab for the production of high precision 1M and 16.6M SSC dipole coils suitable for mass production. The design and construction methods builds on the Tevatron tooling and production experience. Details of the design and construction methods and measured coil uniformity of 1M coils will be presented. 4 refs., 10 figs

Finite element modeling of TFTR poloidal field coils

International Nuclear Information System (INIS)

Baumgartner, J.A.; O'Toole, J.A.

1986-01-01

The Tokamak Fusion Test Reactor (TFTR) Poloidal Field (PF) coils were originally analyzed to TFTR design conditions. The coils have been reanalyzed by PPPL and Grumman to determine operating limits under as-built conditions. Critical stress levels, based upon data obtained from the reanalysis of each PF coil, are needed for input to the TFTR simulation code algorithms. The primary objective regarding structural integrity has been to ascertain the magnitude and location of critical internal stresses in each PF coil due to various combinations of electromagnetic and thermally induced loads. For each PF coil, a global finite element model (FEM) of a coil sector is being analyzed to obtain the basic coil internal loads and displacements. Subsequent fine mesh local models of the coil lead stem and lead spur regions produce the magnitudes and locations of peak stresses. Each copper turn and its surrounding insulation are modeled using solid finite elements. The corresponding electromagnetic and thermal analyses are similarly modeled. A series of test beams were developed to determine the best combination of MSC/NASTRAN-type finite elements for use in PF coil analysis. The results of this analysis compare favorably with those obtained by the earlier analysis which was limited in scope

Tesla coil theoretical model and experimental verification

OpenAIRE

Voitkans, Janis; Voitkans, Arnis

2014-01-01

Abstract – In this paper a theoretical model of a Tesla coil operation is proposed. Tesla coil is described as a long line with distributed parameters in a single-wired format, where the line voltage is measured against electrically neutral space. It is shown that equivalent two-wired scheme can be found for a single-wired scheme and already known long line theory can be applied to a Tesla coil. Formulas for calculation of voltage in a Tesla coil by coordinate and calculation of resonance fre...

The Swiss LCT-coil

International Nuclear Information System (INIS)

Vecsey, G.; Benz, H.; Horvath, I.

1985-01-01

With delivery of the coil to ORNL on February 4, 1984, the second phase of the Swiss Large Coil Program - design and construction - was terminated. Mainlines of the Swiss design concept are summarized and related to theoretical calculations, experimental results of the supporting program, fabricational experience and first successful test results. An attempt is made to draw preliminary conclusions with regard to the design of future toroidal systems such as NET

Structure and Misfolding of the Flexible Tripartite Coiled-Coil Domain of Glaucoma-Associated Myocilin.

Science.gov (United States)

Hill, Shannon E; Nguyen, Elaine; Donegan, Rebecca K; Patterson-Orazem, Athéna C; Hazel, Anthony; Gumbart, James C; Lieberman, Raquel L

2017-11-07

Glaucoma-associated myocilin is a member of the olfactomedins, a protein family involved in neuronal development and human diseases. Molecular studies of the myocilin N-terminal coiled coil demonstrate a unique tripartite architecture: a Y-shaped parallel dimer-of-dimers with distinct tetramer and dimer regions. The structure of the dimeric C-terminal 7-heptad repeats elucidates an unexpected repeat pattern involving inter-strand stabilization by oppositely charged residues. Molecular dynamics simulations reveal an alternate accessible conformation in which the terminal inter-strand disulfide limits the extent of unfolding and results in a kinked configuration. By inference, full-length myocilin is also branched, with two pairs of C-terminal olfactomedin domains. Selected variants within the N-terminal region alter the apparent quaternary structure of myocilin but do so without compromising stability or causing aggregation. In addition to increasing our structural knowledge of naturally occurring extracellular coiled coils and biomedically important olfactomedins, this work broadens the scope of protein misfolding in the pathogenesis of myocilin-associated glaucoma. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structure of a designed, right-handed coiled-coil tetramer containing all biological amino acids.

Science.gov (United States)

Sales, Mark; Plecs, Joseph J; Holton, James M; Alber, Tom

2007-10-01

The previous design of an unprecedented family of two-, three-, and four-helical, right-handed coiled coils utilized nonbiological amino acids to efficiently pack spaces in the oligomer cores. Here we show that a stable, right-handed parallel tetrameric coiled coil, called RH4B, can be designed entirely using biological amino acids. The X-ray crystal structure of RH4B was determined to 1.1 Angstrom resolution using a designed metal binding site to coordinate a single Yb(2+) ion per 33-amino acid polypeptide chain. The resulting experimental phases were particularly accurate, and the experimental electron density map provided an especially clear, unbiased view of the molecule. The RH4B structure closely matched the design, with equivalent core rotamers and an overall root-mean-square deviation for the N-terminal repeat of the tetramer of 0.24 Angstrom. The clarity and resolution of the electron density map, however, revealed alternate rotamers and structural differences between the three sequence repeats in the molecule. These results suggest that the RH4B structure populates an unanticipated variety of structures.

Multiple Enlarged Aneurysms in Primary Racemose Hemangioma of the Bronchial Artery: Successful Prophylactic Transcatheter Arterial Embolization Using N-butyl-2-cyanoacrylate and Coils.

Science.gov (United States)

Saiga, Atsushi; Sugiura, Toshihiko; Higashide, Takashi; Tsuchiya, Satoshi; Nishiyama, Akira; Kubota, Yoshihiro; Horikoshi, Takuro; Uno, Takashi

2018-05-01

An asymptomatic 48-year-old man presented with multiple aneurysms in a primary racemose hemangioma of the right bronchial artery. Bronchial arteriography revealed a tortuous artery with four fusiform aneurysms of varying sizes and aneurysmal dilatation with marked thrombus formation in the long segment of the distal portion. Because the tip of catheter could not pass beyond the aneurysmal dilatation, we performed balloon-occluded embolization using a mixture of N-butyl-2-cyanoacrylate (NBCA) and iodized oil. For four other aneurysms, we performed embolization using a coil alone or with NBCA. After 6 months, right bronchial arteriography revealed no enhancement of the aneurysms. Despite the rarity of this procedure, embolization with NBCA is a good option for bronchial artery aneurysm embolization.

Protection of large-stored-energy superconducting coils

International Nuclear Information System (INIS)

Kircher, F.

1975-11-01

When the stored energy of superconducting magnets increases, the problem of the protection of the coil when a quench occurs becomes more and more important, especially if the structure of the coil is such that the energy can be dissipated only in a small part of the coil. The aim of this paper is first to describe a program which enables to predict the increase of temperature inside the coil for several kinds of protection and to give results for KEK pulsed dipoles (under construction and planned for TRISTAN). (auth.)

Modelling Wireless Power Transfer Using an Array of Tesla Coils

Science.gov (United States)

Pierson, Casey Thomas

Wireless power transmission, or WPT, is a well-demonstrated property in electrical science and physics. Coil-and-wave transmission (CWT) consists of two Tesla coils, one powered by a controlled voltage source v src and one connected across a generic load Z 0 , at a mid- to long range distance apart with spherical capacitors at each of their top loads. The literature on the different methods of WPT varies widely, but research of CWT is sparse, lacking especially in the area of computer simulation. Recently, a physical experiment was conducted by Marzolf et al. in [1], and yielded surprising resonant frequencies in the high frequency range. The goal of this research is to answer the question of whether these reosnant frequencies originate in unexplained field effects or in non-ideal circuit behavior, and establish a formal model to indicate at what frequencies the resonant peaks occur as a first approximation. By carefully constructing a simulation of the most geometrically simple, power efficient design in the work of Marzolf et al. using the scientific software Octave, we investigate these frequencies computationally: first, an ideal scenario that has no flux leakage or exterior losses is modelled mathematically and simulated, and then, a non-ideal scenario that accounts for losses in the coils and surroundings is modelled mathematically and simulated. Both models utilize a simple formula for spherical capacitance for the top loads. After running these simulations through detailed sampling up to 4 MHz, the ideal model could not account for the resonant peaks, while the non-ideal model indicated the resonant peaks near the exact frequency ranges that were observed. An unexpected characteristic of these results was that coupling coefficients between the coils of the transmitter and receiver played a noticeable part in the indication of resonant peaks. This demonstrates that unknown field effects are not the primary driver of resonance in the ideal or non

Magnetic field systems employing a superconducting D.C. field coil

International Nuclear Information System (INIS)

Bartram, T.C.; Hazell, P.A.

1977-01-01

Method and equipment for transferring energy to or from a direct-current superconducting field coil to change the magnetic field generated by the coil in which a second direct-current superconducting coil is used as a storage coil, and energy transfer between the field coil and the storage coil is effected automatically in dependence upon a control program. Preferably, the control program acts upon a variable transformer which is coupled by respective rectifier/inverters to the field and storage coils and also serves for intital supply of energy to the coils

DEVELOPMENT OF COILED TUBING STRESS ANALYSIS

Directory of Open Access Journals (Sweden)

Davorin Matanović

1998-12-01

Full Text Available The use of coiled tubing is increasing rapidly with drilling of horizontal wells. To satisfy all requirements (larger mechanical stresses, larger fluid capacities the production of larger sizes and better material qualities was developed. Stresses due to axial forces and pressures that coiled tubing is subjected are close to its performance limits. So it is really important to know and understand the behaviour of coiled tubing to avoid its break, burst or collapse in the well.

MR imaging of colorectal carcinomas using an MR endoscopic coil

International Nuclear Information System (INIS)

Murano, Akihiko; Kido, Choichiro; Sasaki, Fumio; Nakamura, Tsuneya; Kobayashi, Semi; Katoh, Tomoyuki; Hirai, Takashi

1994-01-01

Diagnosis of the depth of wall invasion by rectal carcinoma using MR endoscopy was performed in ten resected specimens, including five rectal carcinomas, three colon carcinomas, two normal gastric wall. In addition, the gastric wall of a pig was examined. MR imaging was done with a 1.5-T Signa Advantage (GE Medical System) system, with the surface coil of the MR endoscope acting as the receiver coil. Five layers could be distinguished in the bowel wall: mucosa, submucosa and muscularis propria divided into circular muscle, longitudinal muscle and intervening connective tissue. Tumors had almost the same signal intensity as muscle. The MR images of colon carcinomas, rectal carcinomas, and extrinsically metastatic involvement of the sigmoid colon by rectal carcinoma all correlated well with the pathological findings. The normal structure of the gastric wall was similar to that of the colon. 3D-fast Spoiled Grass (SPGR) sequence has a fairly short scanning time. Thus, the possibility of precise clinical diagnosis by this method was suggested. (author)

Transmit-receive eddy current probes

International Nuclear Information System (INIS)

Obrutsky, L.S.; Sullivan, S.P.; Cecco, V.S.

1997-01-01

In the last two decades, due to increased inspection demands, eddy current instrumentation has advanced from single-frequency, single-output instruments to multifrequency, computer-aided systems. This has significantly increased the scope of eddy current testing, but, unfortunately, it has also increased the cost and complexity of inspections. In addition, this approach has not always improved defect detectability or signal-to-noise. Most eddy current testing applications are still performed with impedance probes, which have well known limitations. However, recent research at AECL has led to improved eddy current inspections through the design and development of transmit-receive (T/R) probes. T/R eddy current probes, with laterally displaced transmit and receive coils, present a number of advantages over impedance probes. They have improved signal-to-noise ratio in the presence of variable lift-off compared to impedance probes. They have strong directional properties, permitting probe optimization for circumferential or axial crack detection, and possess good phase discrimination to surface defects. They can significantly increase the scope of eddy current testing permitting reliable detection and sizing of cracks in heat exchanger tubing as well as in welded areas of both ferritic and non-ferromagnetic components. This presentation will describe the operating principles of T/R probes with the help of computer-derived normalized voltage diagrams. We will discuss their directional properties and analyze the advantages of using single and multiple T/R probes over impedance probes for specific inspection cases. Current applications to surface and tube testing and some typical inspection results will be described. (author)

COMPASS magnetic field coils and structure systems

International Nuclear Information System (INIS)

Crossland, R.T.; Booth, J.A.; Hayward, R.J.; Keogh, P.; Pratt, A.P.

1987-01-01

COMPASS is a new experimental toroidal assembly of compact design and with a wide range of physics objectives. It is required to operate either as a Tokamak or as a Reversed Field Pinch with interchangeable circular and dee-section vacuum vessels. The Toroidal field is produced by 16 rectangular coils of 4 turns with tapered conductors on the inside which nest together to form a vault to resist the centering forces. The coils are designed to produce a maximum field on axis of 2.1T which requires a current of 91 kA per turn. Two central solenoids and five pairs of coils symmetrically positioned above and below the machine equator provide the poloidal field. Both coil systems are supported form a mechanical support structure which surrounds the machine. This is primarily designed to resist out-of-plane forces on the TF coils but also acts as the base support for the PF coils and vacuum vessels. An illustration of the COMPASS Load Assembly is given and shows the D-shaped vacuum vessel, the major components and the various field windings

Force delivery of Ni-Ti coil springs.

Science.gov (United States)

Manhartsberger, C; Seidenbusch, W

1996-01-01

Sentalloy springs (GAC, Central Islip, N.Y.) of the open and closed type were investigated with a special designed device. The closed coil springs were subjected to a tensile and the open coil springs to a compression test. After a first measurement, the springs were activated for a period of 4 weeks and then reinvestigated with the same procedure. It could be shown distinctly that, with the different coil springs, the force delivery given by the producer could be achieved only within certain limits. To remain in the martensitic plateau, changed activation ranges, and for the Sentalloy coil springs white and red of the open and closed type, also changed force deliveries had to be taken into account. There was a distinct decrease in force delivery between the first and second measurement. After considering the loading curves of all the Sentalloy coil springs and choosing the right activation range respective to the force delivery, it was found that the coil springs deliver a superior clinical behavior and open new treatment possibilities.

Random coil chemical shift for intrinsically disordered proteins

DEFF Research Database (Denmark)

Kjærgaard, Magnus; Brander, Søren; Poulsen, Flemming Martin

2011-01-01

. Temperature has a non-negligible effect on the (13)C random coil chemical shifts, so temperature coefficients are reported for the random coil chemical shifts to allow extrapolation to other temperatures. The pH dependence of the histidine random coil chemical shifts is investigated in a titration series......, which allows the accurate random coil chemical shifts to be obtained at any pH. By correcting the random coil chemical shifts for the effects of temperature and pH, systematic biases of the secondary chemical shifts are minimized, which will improve the reliability of detection of transient secondary...

Instrumentation and test of the Swiss LCT-coil

International Nuclear Information System (INIS)

Zichy, J.A.; Horvath, I.; Jakob, B.; Marinucci, C.; Vecsey, G.; Weymuth, P.; Zellweger, J.

1985-01-01

Just before Christmas 1983 the fabrication of the Swiss LCT-coil was finished. Tests at ambient temperature were performed on the factory site and after delivery in Oak Ridge. To avoid an undesirable delay of the rescheduled Partial-Array Test it was agreed to install the coil without its superconducting bus. In July 1984 the Swiss LCT-coil was successfully cooled down to LHe temperature together with the other two fully installed coils. Besides the cooling system, the instrumentation, measured parameters of the coil and some preliminary results obtained during the ongoing Partial-Array Test are presented

SAR and thermal response effects of a two-arm Archimedean spiral coil in a magnetic induction sensor on a human head.

Science.gov (United States)

Zhang, Ziyi; Liu, Peiguo; Zhou, Dongming; Zhang, Liang; Ding, Liang

2015-01-01

This study investigates the radiation safety of a newly designed magnetic induction sensor. This novel magnetic induction sensor uses a two-arm Archimedean spiral coil (TAASC) as the exciter. A human head model with a real anatomical structure was used to calculate the specific absorption rate (SAR) and temperature change. Computer Simulation Technology (CST) was used to determine the values of the peak 10-g SAR under different operating parameters (current, frequency, horizontal distance between the excitation coil and the receiver coil, vertical distance between the top of the head model and the XOY plane, position of excitation coil, and volume of hemorrhage). Then, the highest response for the SAR and temperature rise was determined. The results showed that this new magnetic induction sensor is safe in the initial state; for safety reasons, the TAASC current should not exceed 4 A. The scalp tissue absorbed most of the electromagnetic energy. The TAASC's SAR/thermal performance was close to that of the circular coil.

Linear motor coil assembly and linear motor

NARCIS (Netherlands)

2009-01-01

An ironless linear motor (5) comprising a magnet track (53) and a coil assembly (50) operating in cooperation with said magnet track (53) and having a plurality of concentrated multi-turn coils (31 a-f, 41 a-d, 51 a-k), wherein the end windings (31E) of the coils (31 a-f, 41 a-e) are substantially

Polymer therapeutics with a coiled coil motif targeted against murine BCL1 leukemia

Czech Academy of Sciences Publication Activity Database

Pola, Robert; Laga, Richard; Ulbrich, Karel; Sieglová, Irena; Král, Vlastimil; Fábry, Milan; Kabešová, Martina; Kovář, Marek; Pechar, Michal

2013-01-01

Roč. 14, č. 3 (2013), s. 881-889 ISSN 1525-7797 R&D Projects: GA ČR GAP301/11/0325; GA AV ČR IAAX00500803 Institutional research plan: CEZ:AV0Z50520514 Institutional support: RVO:61389013 ; RVO:61388971 ; RVO:68378050 Keywords : coiled coil * polymer therapeutics * scFv Subject RIV: CD - Macromolecular Chemistry; EC - Immunology (MBU-M); EB - Genetics ; Molecular Biology (UMG-J) Impact factor: 5.788, year: 2013

Rice Cellulose SynthaseA8 Plant-Conserved Region Is a Coiled-Coil at the Catalytic Core Entrance

Energy Technology Data Exchange (ETDEWEB)

Rushton, Phillip S.; Olek, Anna T.; Makowski, Lee; Badger, John; Steussy, C. Nicklaus; Carpita, Nicholas C.; Stauffacher, Cynthia V. (NEU); (Purdue)

2016-11-22

The crystallographic structure of a rice (Oryza sativa) cellulose synthase, OsCesA8, plant-conserved region (P-CR), one of two unique domains in the catalytic domain of plant CesAs, was solved to 2.4 Å resolution. Two antiparallel α-helices form a coiled-coil domain linked by a large extended connector loop containing a conserved trio of aromatic residues. The P-CR structure was fit into a molecular envelope for the P-CR domain derived from small-angle X-ray scattering data. The P-CR structure and molecular envelope, combined with a homology-based chain trace of the CesA8 catalytic core, were modeled into a previously determined CesA8 small-angle X-ray scattering molecular envelope to produce a detailed topological model of the CesA8 catalytic domain. The predicted position for the P-CR domain from the molecular docking models places the P-CR connector loop into a hydrophobic pocket of the catalytic core, with the coiled-coil aligned near the entrance of the substrate UDP-glucose into the active site. In this configuration, the P-CR coiled-coil alone is unlikely to regulate substrate access to the active site, but it could interact with other domains of CesA, accessory proteins, or other CesA catalytic domains to control substrate delivery.

New superconducting coil configuration for energy storage

International Nuclear Information System (INIS)

Tokorabet, M.; Mailfert, A.; Colteu, A.

1998-01-01

Energy storage using superconducting coils involves the problem of electromagnetic field pollution outside the considered system. Different configurations are widely studied: the torus, the alone solenoid and multiple parallel solenoids enclosed in one container. A new configuration which minimizes the external pollution is studied in this paper. The theoretical system is composed of two spherical distributions of the current which are concentric. The analytical study uses solution of Laplace equations. Parametric study covers energy, flux density and geometrical data. The second study concerns the numerical approach of this design using coaxial solenoids. A comparison between this new system and the known systems is presented as a conclusion. (orig.)

Intensity correction method customized for multi-animal abdominal MR imaging with 3 T clinical scanner and multi-array coil

International Nuclear Information System (INIS)

Mitsuda, Minoru; Yamaguchi, Masayuki; Nakagami, Ryutaro; Furuta, Toshihiro; Fujii, Hirofumi; Sekine, Norio; Niitsu, Mamoru; Moriyama, Noriyuki

2013-01-01

Simultaneous magnetic resonance (MR) imaging of multiple small animals in a single session increases throughput of preclinical imaging experiments. Such imaging using a 3-tesla clinical scanner with multi-array coil requires correction of intensity variation caused by the inhomogeneous sensitivity profile of the coil. We explored a method for correcting intensity that we customized for multi-animal MR imaging, especially abdominal imaging. Our institutional committee for animal experimentation approved the protocol. We acquired high resolution T 1 -, T 2 -, and T 2 * -weighted images and low resolution proton density-weighted images (PDWIs) of 4 rat abdomens simultaneously using a 3T clinical scanner and custom-made multi-array coil. For comparison, we also acquired T 1 -, T 2 -, and T 2 * -weighted volume coil images in the same rats in 4 separate sessions. We used software created in-house to correct intensity variation. We applied thresholding to the PDWIs to produce binary images that displayed only a signal-producing area, calculated multi-array coil sensitivity maps by dividing low-pass filtered PDWIs by low-pass filtered binary images pixel by pixel, and divided uncorrected T 1 -, T 2 -, or T 2 * -weighted images by those maps to obtain intensity-corrected images. We compared tissue contrast among the liver, spinal canal, and muscle between intensity-corrected multi-array coil images and volume coil images. Our intensity correction method performed well for all pulse sequences studied and corrected variation in original multi-array coil images without deteriorating the throughput of animal experiments. Tissue contrasts were comparable between intensity-corrected multi-array coil images and volume coil images. Our intensity correction method customized for multi-animal abdominal MR imaging using a 3T clinical scanner and dedicated multi-array coil could facilitate image interpretation. (author)

The coiled-coil domain of MURC/cavin-4 is involved in membrane trafficking of caveolin-3 in cardiomyocytes.

Science.gov (United States)

Naito, Daisuke; Ogata, Takehiro; Hamaoka, Tetsuro; Nakanishi, Naohiko; Miyagawa, Kotaro; Maruyama, Naoki; Kasahara, Takeru; Taniguchi, Takuya; Nishi, Masahiro; Matoba, Satoaki; Ueyama, Tomomi

2015-12-15

Muscle-restricted coiled-coil protein (MURC), also referred to as cavin-4, is a member of the cavin family that works cooperatively with caveolins in caveola formation and function. Cavins are cytoplasmic proteins with coiled-coil domains and form heteromeric complexes, which are recruited to caveolae in cells expressing caveolins. Among caveolins, caveolin-3 (Cav3) is exclusively expressed in muscle cells, similar to MURC/cavin-4. In the heart, Cav3 overexpression contributes to cardiac protection, and its deficiency leads to progressive cardiomyopathy. Mutations in the MURC/cavin-4 gene have been identified in patients with dilated cardiomyopathy. In the present study, we show the role of MURC/cavin-4 as a caveolar component in the heart. In H9c2 cells, MURC/cavin-4 was localized at the plasma membrane, whereas a MURC/cavin-4 mutant lacking the coiled-coil domain (ΔCC) was primarily localized to the cytoplasm. ΔCC bound to Cav3 and impaired membrane localization of Cav3 in cardiomyocytes. Additionally, although ΔCC did not alter Cav3 mRNA expression, ΔCC decreased the Cav3 protein level. MURC/cavin-4 and ΔCC similarly induced cardiomyocyte hypertrophy; however, ΔCC showed higher hypertrophy-related fetal gene expression than MURC/cavin-4. ΔCC induced ERK activation in cardiomyocytes. Transgenic mice expressing ΔCC in the heart (ΔCC-Tg mice) showed impaired cardiac function accompanied by cardiomyocyte hypertrophy and marked interstitial fibrosis. Hearts from ΔCC-Tg mice showed a reduction of the Cav3 protein level and activation of ERK. These results suggest that MURC/cavin-4 requires its coiled-coil domain to target the plasma membrane and to stabilize Cav3 at the plasma membrane of cardiomyocytes and that MURC/cavin-4 functions as a crucial caveolar component to regulate cardiac function. Copyright © 2015 the American Physiological Society.

Manufacturing Development of the NCSX Modular Coil Windings

International Nuclear Information System (INIS)

Chrzanowski, JH; Fogarty, PJ; Heitzenroeder, PJ; Meighan, T.; Nelson, B.; Raftopoulos, S.; Williamson, D.

2005-01-01

The modular coils on the National Compact Stellarator Experiment (NCSX) present a number of significant engineering challenges due to their complex shapes, requirements for high dimensional accuracy and the high current density required in the modular coils due to space constraints. In order to address these challenges, an R and D program was established to develop the conductor, insulation scheme, manufacturing techniques, and procedures. A prototype winding named Twisted Racetrack Coil (TRC) was of particular importance in dealing with these challenges. The TRC included a complex shaped winding form, conductor, insulation scheme, leads and termination, cooling system and coil clamps typical of the modular coil design. Even though the TRC is smaller in size than a modular coil, its similar complex geometry provided invaluable information in developing the final design, metrology techniques and development of manufacturing procedures. In addition a discussion of the development of the copper rope conductor including ''Keystoning'' concerns; the epoxy impregnation system (VPI) plus the tooling and equipment required to manufacture the modular coils will be presented

Racetrack coil instability resulting from friction-heat generation at fixtures

International Nuclear Information System (INIS)

Yazawa, T.; Urata, M.; Chandratilleke, G.R.; Maeda, H.

1993-01-01

This paper describes racetrack coil instability resulting from friction-heat generation at fixtures and a preventive measure against it using a thermal barrier. Epoxy impregnated racetrack coils sometimes experience premature quenches due to frictional heat produced by coil slides at fixtures that are essential for the coil straight part to withstand the electromagnetic force. Experimentally, we confirmed for a small-sized racetrack coil that coil slides were actually occurring. The coil movements coupled with acoustic emissions were observed several times when the coil was energized. Each of them was about 10 μm, an equivalent of 20 mJ in frictional heat. This frictional heat was almost comparable with the analytical and experimental coil stability margins when an insulation layer was thin. One of the effective measures against the frictional heat is the thermal barrier, which is a thick insulation layer at the interface between the coil and the fixtures. By thickening the insulation layer from 0.36 to 1.00 mm, the coil stability margin increased from 100 to 200 mJ. (orig.)

Deep brain transcranial magnetic stimulation using variable "Halo coil" system

Science.gov (United States)

Meng, Y.; Hadimani, R. L.; Crowther, L. J.; Xu, Z.; Qu, J.; Jiles, D. C.

2015-05-01

Transcranial Magnetic Stimulation has the potential to treat various neurological disorders non-invasively and safely. The "Halo coil" configuration can stimulate deeper regions of the brain with lower surface to deep-brain field ratio compared to other coil configurations. The existing "Halo coil" configuration is fixed and is limited in varying the site of stimulation in the brain. We have developed a new system based on the current "Halo coil" design along with a graphical user interface system that enables the larger coil to rotate along the transverse plane. The new system can also enable vertical movement of larger coil. Thus, this adjustable "Halo coil" configuration can stimulate different regions of the brain by adjusting the position and orientation of the larger coil on the head. We have calculated magnetic and electric fields inside a MRI-derived heterogeneous head model for various positions and orientations of the coil. We have also investigated the mechanical and thermal stability of the adjustable "Halo coil" configuration for various positions and orientations of the coil to ensure safe operation of the system.

Large magnetic coils for fusion technology

International Nuclear Information System (INIS)

Komarek, P.; Ulbricht, A.

1989-01-01

This paper reviews the current status of research in this field and outlines future tasks and experiments for the Next European Torus (NET). Research and development work accomplished so far permits generation and safe operation of magnetic fields up to 9 T by means of NbTi coils. Fields up to 11 T are feasible if the coils are cooled with superfluid helium at 1.8 K. The potential of the Nb 3 Sn coils promise achievement of magnetic fields between 12 and 13 T. (MM) [de

Novel method of aligning ATF-1 coils

International Nuclear Information System (INIS)

Rome, J.A.; Harris, J.H.; Neilson, G.H.; Jernigan, T.C.

1983-08-01

The coils for the Advanced Toroidal Facility (ATF-1) torsatron may be easily aligned before the machine is placed under vacuum. This is done by creating nulls in the magnetic field by energizing the coils in various configurations. All of the nulls in vertical bar B vector vertical bar occur on the z-axis. When the nulls coincide, the coils are properly aligned

Structural mapping of the coiled-coil domain of a bacterial condensin and comparative analyses across all domains of life suggest conserved features of SMC proteins.

Science.gov (United States)

Waldman, Vincent M; Stanage, Tyler H; Mims, Alexandra; Norden, Ian S; Oakley, Martha G

2015-06-01

The structural maintenance of chromosomes (SMC) proteins form the cores of multisubunit complexes that are required for the segregation and global organization of chromosomes in all domains of life. These proteins share a common domain structure in which N- and C- terminal regions pack against one another to form a globular ATPase domain. This "head" domain is connected to a central, globular, "hinge" or dimerization domain by a long, antiparallel coiled coil. To date, most efforts for structural characterization of SMC proteins have focused on the globular domains. Recently, however, we developed a method to map interstrand interactions in the 50-nm coiled-coil domain of MukB, the divergent SMC protein found in γ-proteobacteria. Here, we apply that technique to map the structure of the Bacillus subtilis SMC (BsSMC) coiled-coil domain. We find that, in contrast to the relatively complicated coiled-coil domain of MukB, the BsSMC domain is nearly continuous, with only two detectable coiled-coil interruptions. Near the middle of the domain is a break in coiled-coil structure in which there are three more residues on the C-terminal strand than on the N-terminal strand. Close to the head domain, there is a second break with a significantly longer insertion on the same strand. These results provide an experience base that allows an informed interpretation of the output of coiled-coil prediction algorithms for this family of proteins. A comparison of such predictions suggests that these coiled-coil deviations are highly conserved across SMC types in a wide variety of organisms, including humans. © 2015 Wiley Periodicals, Inc.

Dual levitated coils for antihydrogen production

Science.gov (United States)

Wofford, J. D.; Ordonez, C. A.

2013-04-01

Two coaxial superconducting magnetic coils that carry currents in the same direction and that are simultaneously levitated may serve for antihydrogen plasma confinement. The configuration may be suitable for use by a collaboration at the CERN Antiproton Decelerator facility to test fundamental symmetries between the properties of hydrogen and antihydrogen. Nested Penning traps are currently used to confine recombining antihydrogen plasma. Symmetry studies require the production of sufficiently cold antihydrogen. However, plasma drifts within nested Penning traps can increase the kinetic energy of antiprotons that form antihydrogen atoms. Dual levitated coils may serve to confine relatively large, cold, dense non-drifting recombining antihydrogen plasmas. A minimum-B magnetic field that is produced by the coils could provide for atom trapping. A toroidal plasma is confined between the coils. High density plasmas may be possible, by allowing plasma pressure to balance mechanical pressure to keep the coils apart. Progress is reported on theoretical and experimental efforts. The theoretical effort includes the development of a classical trajectory Monte Carlo simulation of confinement. The experimental effort includes levitation of a NdFeB permanent ring magnet, which produces a magnetic field that is qualitatively similar to the field that would be produced by the two coaxial superconducting magnetic coils. Liquid-nitrogen-cooled Bi-2223 high-temperature-superconducting components, with a critical temperature of 108 K, were used to levitate the ring magnet. An issue concerning keeping the plane of the levitated ring horizontal is discussed.

Surge analysis of the MAGLEV coil for propulsion and guidance; Jiki fujoshiki tetsudo ni okeru suitei annaiyo coil no surge kaiseki

Energy Technology Data Exchange (ETDEWEB)

Ema, S [Numazu College of Technology, Shizuoka (Japan)

1995-11-20

The MAGLEV (magnetically levitated train) is now well along in development testing in Japan. MAGLEV is unlike conventional railways, so various problems lie in the technology of MAGLEV. One of them is surge analysis of the MAGLEV coil for propulsion and guidance (`coil for propulsion` for short). The coil for propulsion is installed on each side of the outdoor guideway. Thus, the power system of MAGLEV is always exposed to lightning and circuit switching. Accordingly, it is very important to do a rational insulation plan to prevent damage when surges enter the coils. In view of this situation I performed experiments using the mini model coils and clarified impulse voltage distribution at the end of each coil and simulated the surge characteristics by giving the inverted L equivalent circuit to the coil for propulsion. As a result, the measured values and calculated values were almost equal in the surge characteristics. Further, the surge characteristics of the Miyazaki test track and the future MAGLEV were examined. 10 refs., 17 figs., 1 tab.

Coil Array Design Inspired on the Kepler's Lenten Pretzel

International Nuclear Information System (INIS)

Vazquez, F.; Solis, S. E.; Rodriguez, A. O.

2008-01-01

The RF coil arrays are an important part in Magnetic Resonance Imaging, since they are the main device for transmission and reception of the magnetic resonance signal. An RF coil array with a new configuration based on the Kepler's Lenten pretzel for the geocentric path of Mars is proposed in this work. The evenly distributed trajectories may serve as the basic configuration to form a coil array to adequately cover a region of interest for magnetic resonance experiments. The main goal is to investigate the electromagnetic properties of this coil array geometry to obtain an optimal design for its further construction. Hence, the electromagnetic properties of the coil array were numerical simulated using the finite element method and the quasi-static approach. Resulting simulations showed that there is an important concentration of magnetic field lines at the centre of the coil array. This is an advantage over other coil arrays where the magnetic field usually decreased at their geometrical centre. Both the electric and magnetic fields had also a very good uniformity. These characteristics made this coil design a good candidate for applications where the use of multi-coil technology is mandatory

Tolerance Evaluation of Poloidal Shear Keys for ITER TF Coil

International Nuclear Information System (INIS)

Fu Youkun; Neil, M.; Cees Jong

2006-01-01

There are 18 ITER Toroidal Field (TF) Coils. Unlike the other ITER coils, these coils are structurally linked. These links consist of friction between the coil legs in the central vault formed by the inner straight legs of the coils, four outer inter-coil structures (OIS) and one inner inter-coil structure (IIS). The OIS consists essentially of bands around all 18 coils to provide shear support by forming shear panels with the coil case, and the IIS consists of poloidal circular keys placed directly between the coil cases. Global analysis of the 'perfect' coil shape has shown high stresses in the IIS, in the poloidal keyways. Optimization has successfully reduced these stresses to acceptable values as regards the expected fatigue resistance. However it is necessary to confirm that the stresses are still acceptable when realistic values of geometry variations are included (i.e. the effect of coil and case tolerances). Because of the extensive mechanical links between coils the poloidal key stresses can also be affected by tolerances elsewhere in the case. As the first step in assessment of the possible variations in stresses, a substructure technique is being used to develop a local model of the key region. The result of geometry variations between individual coils is a loss in the 18 fold symmetry used to simplify previous analyses. With the new and optimized model it should be possible to relax the 18-fold symmetry, but a full analysis of all 18 coils is still not possible. Systematic ways of representing the tolerance variation in the finite element model have been developed so that parametric studies can be undertaken without a full reconstruction of the model. (author)

Fault Analysis of ITER Coil Power Supply System

International Nuclear Information System (INIS)

Song, In Ho; Jun, Tao; Benfatto, Ivone

2009-01-01

The ITER magnet coils are all designed using superconductors with high current carrying capability. The Toroidal Field (TF) coils operate in a steadystate mode with a current of 68 kA and discharge the stored energy in case of quench with using 9 interleaved Fast Discharge Units (FDUs). The Central Solenoid (CS) coils and Poloidal Field (PF) coils operate in a pulse mode with currents of up to 45 kA and require fast variation of currents inducing more than 10 kV during normal operation on the coil terminals using Switching Network (SN) systems (CSs, PF1 and 6) and Booster and VS converters (PF2 to 5), which are series connected to Main converters. SN and FDU systems comprise high current DC circuit breakers and resistors for generating high voltage (SN) and to dissipate magnetic energy (FDUs). High transient voltages can arise due to the switching operation of SN and FD and the characteristics of resistors and stray components of DC distribution systems. Also, faults in power supply control such as shorts or grounding faults can produce higher voltages between terminals and between terminal and ground. Therefore, the design of the coil insulation, coil terminal regions, feeders, feed throughs, pipe breaks and instrumentation must take account of these high voltages during normal and abnormal conditions. Voltage insulation level can be defined and it is necessary to test the coils at higher voltages, to be sure of reliable performance during the lifetime of operation. This paper describes the fault analysis of the TF, CS and PF coil power supply systems, taking account of the stray parameter of the power supply and switching systems and inductively coupled superconducting coil models. Resistor grounding systems are included in the simulation model and all fault conditions such as converter hardware and software faults, switching system hardware and software faults, DC short circuits and single grounding faults are simulated. The occurrence of two successive faults

A precise technique for manufacturing correction coil

International Nuclear Information System (INIS)

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

Robust SMES controller design for stabilization of inter-area oscillation considering coil size and system uncertainties

International Nuclear Information System (INIS)

Ngamroo, Issarachai

2010-01-01

It is well known that the superconducting magnetic energy storage (SMES) is able to quickly exchange active and reactive power with the power system. The SMES is expected to be the smart storage device for power system stabilization. Although the stabilizing effect of SMES is significant, the SMES is quite costly. Particularly, the superconducting magnetic coil size which is the essence of the SMES, must be carefully selected. On the other hand, various generation and load changes, unpredictable network structure, etc., cause system uncertainties. The power controller of SMES which is designed without considering such uncertainties, may not tolerate and loses stabilizing effect. To overcome these problems, this paper proposes the new design of robust SMES controller taking coil size and system uncertainties into account. The structure of the active and reactive power controllers is the 1st-order lead-lag compensator. No need for the exact mathematical representation, system uncertainties are modeled by the inverse input multiplicative perturbation. Without the difficulty of the trade-off of damping performance and robustness, the optimization problem of control parameters is formulated. The particle swarm optimization is used for solving the optimal parameters at each coil size automatically. Based on the normalized integral square error index and the consideration of coil current constraint, the robust SMES with the smallest coil size which still provides the satisfactory stabilizing effect, can be achieved. Simulation studies in the two-area four-machine interconnected power system show the superior robustness of the proposed robust SMES with the smallest coil size under various operating conditions over the non-robust SMES with large coil size.

Robust SMES controller design for stabilization of inter-area oscillation considering coil size and system uncertainties

Science.gov (United States)

Ngamroo, Issarachai

2010-12-01

It is well known that the superconducting magnetic energy storage (SMES) is able to quickly exchange active and reactive power with the power system. The SMES is expected to be the smart storage device for power system stabilization. Although the stabilizing effect of SMES is significant, the SMES is quite costly. Particularly, the superconducting magnetic coil size which is the essence of the SMES, must be carefully selected. On the other hand, various generation and load changes, unpredictable network structure, etc., cause system uncertainties. The power controller of SMES which is designed without considering such uncertainties, may not tolerate and loses stabilizing effect. To overcome these problems, this paper proposes the new design of robust SMES controller taking coil size and system uncertainties into account. The structure of the active and reactive power controllers is the 1st-order lead-lag compensator. No need for the exact mathematical representation, system uncertainties are modeled by the inverse input multiplicative perturbation. Without the difficulty of the trade-off of damping performance and robustness, the optimization problem of control parameters is formulated. The particle swarm optimization is used for solving the optimal parameters at each coil size automatically. Based on the normalized integral square error index and the consideration of coil current constraint, the robust SMES with the smallest coil size which still provides the satisfactory stabilizing effect, can be achieved. Simulation studies in the two-area four-machine interconnected power system show the superior robustness of the proposed robust SMES with the smallest coil size under various operating conditions over the non-robust SMES with large coil size.

Measurement of a Conduction Cooled Nb3Sn Racetrack Coil

Science.gov (United States)

Kim, HS; Kovacs, C.; Rochester, J.; Sumption, MD; Tomsic, M.; Peng, X.; Doll, D.

2017-12-01

Use of superconducting coils for wind turbines and electric aircraft is of interest because of the potential for high power density and weight reduction. Here we test a racetrack coil developed as a proof-of-concept for cryogen-free superconducting motors and generators. The coil was wound with 1209 m of 0.7-mm-diameter insulated tube-type Nb3Sn wire. The coil was epoxy-impregnated, instrumented, covered with numerous layers of aluminized mylar insulation, and inserted vertically into a dewar. The system was cooled to 4.2 K, and a few inches of liquid helium was allowed to collect at the bottom of the dewar but below the coil. The coil was cooled by conduction via copper cooling bars were attached to the coil but also were immersed in the liquid helium at their lower ends. Several current tests were performed on the coil, initially in voltage mode, and one run in current mode. The maximum coil Ic at 4.2 K was 480 A, generating 3.06 T at the surface of the coil. The coil met the design targets with a noticeable margin.

An 8/15-channel Tx/Rx head neck RF coil combination with region-specific B1 + shimming for whole-brain MRI focused on the cerebellum at 7T.

Science.gov (United States)

Pfaffenrot, Viktor; Brunheim, Sascha; Rietsch, Stefan H G; Koopmans, Peter J; Ernst, Thomas M; Kraff, Oliver; Orzada, Stephan; Quick, Harald H

2018-02-09

To design and evaluate an 8/15-channel transmit/receive (Tx/Rx) head-neck RF coil combination with region-specific B1+ shimming for whole-brain MRI with focus on improved functional MRI of the cerebellum at 7 T. An 8-channel transceiver RF head coil was combined with a 7-channel receive-only array. The noise parameters and acceleration capabilities of this 8Tx/15Rx coil setup were compared with a commercially available 1Tx/32Rx RF head coil. Region-specific 8-channel B1+ shimming was applied when using the 8Tx/15Rx RF coil. To evaluate the capability for functional MRI of the cerebellum, temporal SNR and statistical nonparametric maps for finger-tapping experiments with 14 healthy subjects were derived by applying a variable slice thickness gradient-echo echo-planar functional MRI sequence. The 8Tx/15Rx setup had a lower maximum noise correlation between channels, but higher average correlations compared with the 1Tx/32Rx coil. Both RF coils exhibited identical g-factors in the cerebellum with R = 3 acceleration. The enlarged FOV of the 8Tx/15Rx coil in combination with region-specific B1+ shimming increased homogeneity of the transmission field and temporal SNR in caudal cerebellar regions. Temporal SNR losses in cranial parts were reduced, resulting in more highly significant voxels in the caudally activated areas and identical patterns in the cranial cerebellar parts during a finger-tapping task. Compared with the 1Tx/32Rx RF coil, the presented 8Tx/15Rx RF coil combination successfully improves functional MRI of the human cerebellum at 7 T while maintaining whole-brain coverage. A clear temporal SNR gain in caudal cerebellar regions is shown. © 2018 International Society for Magnetic Resonance in Medicine.

Eddy current testing probe with dual half-cylindrical coils

Science.gov (United States)

Bae, Byung-Hoon; Choi, Jung-Mi; Kim, Soo-Yong

2000-02-01

We have developed a new eddy current probe composed of a dual half-cylindrical (2HC) coil as an exciting coil and a sensing coil that is placed in the small gap of the 2HC coil. The 2HC coil induces a linear eddy current on the narrow region within the target medium. The magnitude of eddy current has a maximum peak with the narrow width, underneath the center of the exciting 2HC coil. Because of the linear eddy current, the probe can be used to detect not only the existence of a crack but also its direction in conducting materials. Using specimen with a machined crack, and varying the exciting frequency from 0.5 to 100 kHz, we investigated the relationships between the direction of crack and the output voltage of the sensing coil.

Development of superconducting pulsed poloidal coil in JAERI

International Nuclear Information System (INIS)

Shimamoto, S.; Okuno, K.; Ando, T.; Tsuji, H.

1990-01-01

In the Japan Atomic Energy Research Institute, (JAERI), development work on pulsed superconductors and coils started in 1979, aiming at the demonstration of the applicability of superconducting technologies to pulsed poloidal coils in a fusion reactor. Initially our effort was concentrated mainly on the development of pool-cooled large-current pulsed conductors. Over the past ten years, superconducting technology has made great progress and the forced-flow cooled coil has assumed great importance in the development work. Now the Demo Poloidal Coil Project is in progress in JAERI, and three large forced-flow cooled coils have so far been fabricated and tested. Many improvements have been achieved in ac-loss performance and mechanical characteristics. (author)

BECN2 interacts with ATG14 through a metastable coiled-coil to mediate autophagy: BECN2 CCD Structure and Interaction with ATG14

Energy Technology Data Exchange (ETDEWEB)

Su, Minfei; Li, Yue; Wyborny, Shane; Neau, David; Chakravarthy, Srinivas; Levine, Beth; Colbert, Christopher L.; Sinha, Sangita C. (NDSU); (IIT); (Cornell); (UTSMC)

2017-03-12

ATG14 binding to BECN/Beclin homologs is essential for autophagy, a critical catabolic homeostasis pathway. Here, we show that the α-helical, coiled-coil domain (CCD) of BECN2, a recently identified mammalian BECN1 paralog, forms an antiparallel, curved homodimer with seven pairs of nonideal packing interactions, while the BECN2 CCD and ATG14 CCD form a parallel, curved heterodimer stabilized by multiple, conserved polar interactions. Compared to BECN1, the BECN2 CCD forms a weaker homodimer, but binds more tightly to the ATG14 CCD. Mutation of nonideal BECN2 interface residues to more ideal pairs improves homodimer self-association and thermal stability. Unlike BECN1, all BECN2 CCD mutants bind ATG14, although more weakly than wild type. Thus, polar BECN2 CCD interface residues result in a metastable homodimer, facilitating dissociation, but enable better interactions with polar ATG14 residues stabilizing the BECN2:ATG14 heterodimer. These structure-based mechanistic differences in BECN1 and BECN2 homodimerization and heterodimerization likely dictate competitive ATG14 recruitment.

Testing of the European LCT coil in the TOSKA facility

International Nuclear Information System (INIS)

Herz, W.; Katheder, H.; Krauth, H.

1985-01-01

The EURATOM-LCT coil was tested as a single coil in TOSKA. Load cells were mounted in the support structure to monitor forces between coil and vacuum vessel during cooldown and coil charging. Disturbances of components by magnetic fringing fields were carefully considered. To investigate the mechanical behaviour and compare it with FEM-calculations the coil was equipped with strain gauge rosettes and displacement transducers. Van Mises stresses in the coil case are in agreement with calculations. As known from special investigations during coil manufacturing the average radial Young modulus varies along the periphery caused by the different curvatures. This leads to differences with FEM-calculation (larger gaps between winding and coil case) assuming a larger constant Young modulus performed at the beginning of the project

Comparison of endorectal coil and nonendorectal coil T2W and diffusion-weighted MRI at 3 Tesla for localizing prostate cancer: correlation with whole-mount histopathology.

Science.gov (United States)

Turkbey, Baris; Merino, Maria J; Gallardo, Elma Carvajal; Shah, Vijay; Aras, Omer; Bernardo, Marcelino; Mena, Esther; Daar, Dagane; Rastinehad, Ardeshir R; Linehan, W Marston; Wood, Bradford J; Pinto, Peter A; Choyke, Peter L

2014-06-01

To compare utility of T2-weighted (T2W) MRI and diffusion-weighted MRI (DWI-MRI) obtained with and without an endorectal coil at 3 Tesla (T) for localizing prostate cancer. This Institutional Review Board-approved study included 20 patients (median prostate-specific antigen, 8.4 ng/mL). Patients underwent consecutive prostate MRIs at 3T, first with a surface coil alone, then with combination of surface, endorectal coils (dual coil) followed by robotic assisted radical prostatectomy. Lesions were mapped at time of acquisition on dual-coil T2W, DWI-MRI. To avoid bias, 6 months later nonendorectal coil T2W, DWI-MRI were mapped. Both MRI evaluations were performed by two readers blinded to pathology with differences resolved by consensus. A lesion-based correlation with whole-mount histopathology was performed. At histopathology 51 cancer foci were present ranging in size from 2 to 60 mm. The sensitivity of the endorectal dual-coil, nonendorectal coil MRIs were 0.76, 0.45, respectively. PPVs for endorectal dual-coil, nonendorectal coil MRI were 0.80, 0.64, respectively. Mean size of detected lesions with nonendorectal coil MRI were larger than those detected by dual-coil MRI (22 mm versus 17.4 mm). Dual-coil prostate MRI detected more cancer foci than nonendorectal coil MRI. While nonendorectal coil MRI is an attractive alternative, physicians performing prostate MRI should be aware of its limitations. Copyright © 2013 Wiley Periodicals, Inc.

Multiple Interference Cancellation Performance for GPS Receivers with Dual-Polarized Antenna Arrays

Directory of Open Access Journals (Sweden)

Moeness G. Amin

2008-11-01

Full Text Available This paper examines the interference cancellation performance in global positioning system (GPS receivers equipped with dual-polarized antenna arrays. In dense jamming environment, different types of interferers can be mitigated by the dual-polarized antennas, either acting individually or in conjunction with other receiver antennas. We apply minimum variance distorntionless response (MVDR method to a uniform circular dual-polarized antenna array. The MVDR beamformer is constructed for each satellite. Analysis of the eigenstructures of the covariance matrix and the corresponding weight vector polarization characteristics are provided. Depending on the number of jammers and jammer polarizations, the array chooses to expend its degrees of freedom to counter the jammer polarization or/and use phase coherence to form jammer spatial nulls. Results of interference cancellations demonstrate that applying multiple MVDR beamformers, each for one satellite, has a superior cancellation performance compared to using only one MVDR beamformer for all satellites in the field of view.

Retrieval of prolapsed coils during endovascular treatment of cerebral aneurysms

International Nuclear Information System (INIS)

Dinc, Hasan; Kuzeyli, Kayhan; Kosucu, Polat; Sari, Ahmet; Cekirge, Saruhan

2006-01-01

One of the feared complications during detachable coil embolization of cerebral aneurysms is herniation of a coil loop into the parent artery. Although coil protrusion of one or two loops into the parent vessel may not cause adverse events and in some instances can be ignored, the authors believe that coil retrieval is indicated if a free end is seen pulsating along the blood flow stream to prevent migration of the entire coil mass. In one patient, a microballoon was inflated across the neck of the aneurysm during retrieval of a herniated coil to prevent further coil herniation from the aneurysm sac. We present two cases in which prolapsed coils were successfully retrieved either using a microsnare and balloon combination or a microsnare alone. This report focuses on the efficacy of the Amplatz microsnare for such retrievals and the circumstances in which a herniated coil needs to be retrieved. We report two cases in which embolization coils partially migrated into the parent artery during endovascular treatment of cerebral aneurysm and were retrieved using the Amplatz Nitinol microsnare. (orig.)

Slip-spring model of entangled rod-coil block copolymers

Science.gov (United States)

Wang, Muzhou; Likhtman, Alexei E.; Olsen, Bradley D.

2015-03-01

Understanding the dynamics of rod-coil block copolymers is important for optimal design of functional nanostructured materials for organic electronics and biomaterials. Recently, we proposed a reptation theory of entangled rod-coil block copolymers, predicting the relaxation mechanisms of activated reptation and arm retraction that slow rod-coil dynamics relative to coil and rod homopolymers, respectively. In this work, we introduce a coarse-grained slip-spring model of rod-coil block copolymers to further explore these mechanisms. First, parameters of the coarse-grained model are tuned to match previous molecular dynamics simulation results for coils, rods, and block copolymers. For activated reptation, rod-coil copolymers are shown to disfavor configurations where the rod occupies curved portions of the entanglement tube of randomly varying curvature created by the coil ends. The effect of these barriers on diffusion is quantitatively captured by considering one-dimensional motion along an entanglement tube with a rough free energy potential. Finally, we analyze the crossover between the two mechanisms. The resulting dynamics from both mechanisms acting in combination is faster than from each one individually.

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

International Nuclear Information System (INIS)

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

2013-01-01

Highlights: ► We fabricated a large HTS gradiometer with 350-mm-long baseline. ► A 6-turn gradiometric planar pickup was made of a HTS coated conductor. ► A 26-turn HTS input coil chip was stacked on a HTS thin film gradiometer chip. ► A mechanical balancing structure was also implemented. ► The fabricated gradiometer showed a gradient field noise of 0.8 fT/cm Hz 1/2 . -- Abstract: 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 GdBa 2 Cu 3 O y 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 Hz 1/2 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

Oncogenic TPM3-ALK activation requires dimerization through the coiled-coil structure of TPM3

International Nuclear Information System (INIS)

Amano, Yosuke; Ishikawa, Rie; Sakatani, Toshio; Ichinose, Junji; Sunohara, Mitsuhiro; Watanabe, Kousuke; Kage, Hidenori; Nakajima, Jun; Nagase, Takahide; Ohishi, Nobuya; Takai, Daiya

2015-01-01

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal tumor that can arise from anywhere in the body. Anaplastic lymphoma kinase (ALK) gene rearrangements, most often resulting in the tropomyosin 3 (TPM3)-ALK fusion gene, are the main causes of IMT. However, the mechanism of malignant transformation in IMT has yet to be elucidated. The purpose of this study was to clarify the role of the TPM3 region in the transformation of IMT via TPM3-ALK. Lentivirus vectors containing a TPM3-ALK fusion gene lacking various lengths of TPM3 were constructed and expressed in HEK293T and NIH3T3 cell lines. Focus formation assay revealed loss of contact inhibition in NIH3T3 cells transfected with full-length TPM3-ALK, but not with ALK alone. Blue-native polyacrylamide gel electrophoresis (BN-PAGE) revealed that TPM3-ALK dimerization increased in proportion to the length of TPM3. Western blot showed phosphorylation of ALK, ERK1/2, and STAT3 in HEK293T cells transfected with TPM3-ALK. Thus, the coiled-coil structure of TPM3 contributes to the transforming ability of the TPM3-ALK fusion protein, and longer TPM3 region leads to higher dimer formation. - Highlights: • TPM3-ALK fusion protein dimerizes through the coiled-coil structure of TPM3. • Longer coiled-coil structure of TPM3 leads to higher TPM3-ALK dimer formation. • Presence of TPM3-ALK dimer leads to ALK, STAT3, and ERK1/2 phosphorylation. • Presence of TPM3-ALK leads to loss of contact inhibition. • BN-PAGE is a simple technique for visualizing oncogenic dimerization

Oncogenic TPM3-ALK activation requires dimerization through the coiled-coil structure of TPM3

Energy Technology Data Exchange (ETDEWEB)

Amano, Yosuke; Ishikawa, Rie; Sakatani, Toshio [Department of Respiratory Medicine, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Ichinose, Junji [Department of Cardiothoracic Surgery, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Sunohara, Mitsuhiro; Watanabe, Kousuke; Kage, Hidenori [Department of Respiratory Medicine, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Nakajima, Jun [Department of Cardiothoracic Surgery, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Nagase, Takahide; Ohishi, Nobuya [Department of Respiratory Medicine, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Takai, Daiya, E-mail: dtakai-ind@umin.ac.jp [Department of Respiratory Medicine, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Department of Clinical Laboratory, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan)

2015-02-13

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal tumor that can arise from anywhere in the body. Anaplastic lymphoma kinase (ALK) gene rearrangements, most often resulting in the tropomyosin 3 (TPM3)-ALK fusion gene, are the main causes of IMT. However, the mechanism of malignant transformation in IMT has yet to be elucidated. The purpose of this study was to clarify the role of the TPM3 region in the transformation of IMT via TPM3-ALK. Lentivirus vectors containing a TPM3-ALK fusion gene lacking various lengths of TPM3 were constructed and expressed in HEK293T and NIH3T3 cell lines. Focus formation assay revealed loss of contact inhibition in NIH3T3 cells transfected with full-length TPM3-ALK, but not with ALK alone. Blue-native polyacrylamide gel electrophoresis (BN-PAGE) revealed that TPM3-ALK dimerization increased in proportion to the length of TPM3. Western blot showed phosphorylation of ALK, ERK1/2, and STAT3 in HEK293T cells transfected with TPM3-ALK. Thus, the coiled-coil structure of TPM3 contributes to the transforming ability of the TPM3-ALK fusion protein, and longer TPM3 region leads to higher dimer formation. - Highlights: • TPM3-ALK fusion protein dimerizes through the coiled-coil structure of TPM3. • Longer coiled-coil structure of TPM3 leads to higher TPM3-ALK dimer formation. • Presence of TPM3-ALK dimer leads to ALK, STAT3, and ERK1/2 phosphorylation. • Presence of TPM3-ALK leads to loss of contact inhibition. • BN-PAGE is a simple technique for visualizing oncogenic dimerization.

The design of the SULTAN inner coil

International Nuclear Information System (INIS)

Franken, W.M.P.; Spoorenberg, C.J.G.

1981-12-01

The background field of the first phase of the test facility SULTAN will be generated by two concentric solenoids: a 6 Tesla outer coil with a free bore of 1.3 m and an inner coil for increasing the field to 8 Tesla. The free bore (cold) will be 1.055 m. The final design of the 8 Tesla inner coil is described. The coil will operate at an overall current density of 23 x 10 6 A/m 2 . It will be cooled directly by forced flow supercritical helium. A hollow conductor is applied, composed of a rectangular copper tube and a 16 strands Rutherford cable, soldered on one side of the tube. The copper tube will be cold worked to cope with the high stress level (165 MPa). The design base (field and stress analysis, cooling, stability), the mechanical design and the instrumentation will be specified. The design and construction of the coil is a part of the collaboration between ECN and Holec Transformer Group

The bar coil for NMR tomograph

International Nuclear Information System (INIS)

Bogorodzki, P.; Piatkowski, A.; Wasielewski, J.

1995-01-01

The bar coil (bi-planar) for the NMR tomograph, designed for medical diagnostics, has been described. The tests of coil shown that it generates good homogenous magnetic field in a big volume what results in improving of the signal-to-noise ratio

Superconducting coil system and methods of assembling the same

Science.gov (United States)

Rajput-Ghoshal, Renuka; Rochford, James H.; Ghoshal, Probir K.

2016-01-19

A superconducting magnet apparatus is provided. The superconducting magnet apparatus includes a power source configured to generate a current; a first switch coupled in parallel to the power source; a second switch coupled in series to the power source; a coil coupled in parallel to the first switch and the second switch; and a passive quench protection device coupled to the coil and configured to by-pass the current around the coil and to decouple the coil from the power source when the coil experiences a quench.

Salt effects on hydrophobic interaction and charge screening in the folding of a negatively charged peptide to a coiled coil (leucine zipper).

Science.gov (United States)

Jelesarov, I; Dürr, E; Thomas, R M; Bosshard, H R

1998-05-19

The stability of a coiled coil or leucine zipper is controlled by hydrophobic interactions and electrostatic forces between the constituent helices. We have designed a 30-residue peptide with the repeating seven-residue pattern of a coiled coil, (abcdefg)n, and with Glu in positions e and g of each heptad. The glutamate side chains prevented folding at pH values above 6 because of electrostatic repulsion across the helix dimer interface as well as within the individual helices. Protonation of the carboxylates changed the conformation from a random coil monomer to a coiled coil dimer. Folding at alkaline pH where the peptide had a net charge of -7e was promoted by the addition of salts. The nature of the charge screening cation was less important than that of the anion. The high salt concentrations (>1 M) necessary to induce folding indicated that the salt-induced folding resulted from alterations in the protein-water interaction. Folding was promoted by the kosmotropic anions sulfate and fluoride and to a lesser extent by the weak kosmotrope formate, whereas chloride and the strong chaotrope perchlorate were ineffective. Kosmotropes are excluded from the protein surface, which is preferentially hydrated, and this promotes folding by strengthening hydrophobic interactions at the coiled coil interface. Although charge neutralization also contributed to folding, it was effective only when the screening cation was partnered by a good kosmotropic anion. Folding conformed to a two-state transition from random coil monomer to coiled coil dimer and was enthalpy driven and characterized by a change in the heat capacity of unfolding of 3.9 +/- 1.2 kJ mol-1 K-1. The rate of folding was analyzed by fluorescence stopped-flow measurements. Folding occurred in a biphasic reaction in which the rapid formation of an initial dimer (kf = 2 x 10(7) M-1 s-1) was followed by an equally rapid concentration-independent rearrangement to the folded dimer (k > 100 s-1).

A generalized strategy for designing (19)F/(1)H dual-frequency MRI coil for small animal imaging at 4.7 Tesla.

Science.gov (United States)

Hu, Lingzhi; Hockett, Frank D; Chen, Junjie; Zhang, Lei; Caruthers, Shelton D; Lanza, Gregory M; Wickline, Samuel A

2011-07-01

To propose and test a universal strategy for building (19) F/(1) H dual-frequency RF coil that permits multiple coil geometries. The feasibility to design (19) F/(1) H dual-frequency RF coil based on coupled resonator model was investigated. A series capacitive matching network enables robust impedance matching for both harmonic oscillating modes of the coupled resonator. Two typical designs of (19) F/(1) H volume coils (birdcage and saddle) at 4.7T were implemented and evaluated with electrical bench test and in vivo (19) F/(1) H dual-nuclei imaging. For various combinations of internal resistances of the sample coil and secondary resonator, numerical solutions for the tunable capacitors to optimize impedance matching were obtained using a root-seeking program. Identical and homogeneous B1 field distribution at (19) F and (1) H frequencies were observed in bench test and phantom image. Finally, in vivo mouse imaging confirmed the sensitivity and homogeneity of the (19) F/(1) H dual-frequency coil design. A generalized strategy for designing (19) F/(1) H dual-frequency coils based on the coupled resonator approach was developed and validated. A unique feature of this design is that it preserves the B1 field homogeneity of the RF coil at both resonant frequencies. Thus it minimizes the susceptibility effect on image co-registration. Copyright © 2011 Wiley-Liss, Inc.

BPX toroidal field coil design

International Nuclear Information System (INIS)

Heitzenvoeder, D.J.

1992-01-01

This paper reports on the toroidal field (TF) coil system of the Burning Plasma Experiment (BPX) which consists of (18) beryllium copper magnets arrayed in a wedged configuration with a major radius of 2.6 meters and a field strength capability on axis of 9.0 Tesla. The toroidal array is constructed from six (3)-coil modules to facilitate remote recovery in the event of a magnet failure after nuclear activation precludes hands-on servicing. The magnets are of a modified Bitter plate design with partial cases of type 316-LN stainless steel welded with Inconel 182 weld wire. The coil turn plates are fabricated from CDA C17510 beryllium copper with optimized mechanical, thermal, and electrical characteristics. joints within the turns and between turns are made by welding with C17200 filler wire. Cryogenic cooling is employed to reduce power dissipation and to enhance performance. The magnets are cooled between experimental pulses by pressurized liquid nitrogen flowing through channels in the edges of the coil turns. This arrangement makes possible one full-power pulse per hour. Electrical insulation consists of polyimide-glass sheets bonded in place with vacuum-pressure impregnated epoxy/glass

Finite element coiled cochlea model

Science.gov (United States)

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.

Demonstration poloidal coil test facility

International Nuclear Information System (INIS)

Sato, Masahiko; Kawano, Katumi; Tada, Eisuke

1989-01-01

A new compact cryogenic cold compressor was developed by Japan Atomic Energy Research Institute (JAERI) in collaboration with Isikawajima-Harima Heavy Industries Co., Ltd. (IHI) in order to produce the supercritical helium below 4.2 K for Demonstration Poloidal Coils (DPC) which are forced-flow cooled type superconducting pulse coils. This compressor is one of key components for DPC test facility. The cold compressor reduces pressure in liquid helium bath, which contains liquid helium of around 3,000 l, down to 0.5 atm efficiently. Consequently, supercritical helium down to 3.5 K is produced and supplied to the DPC coils. A centrifugal compressor with dynamic gas bearing is selected as a compressor mechanism to realize high adiabatic efficiency and large flow rate. In this performance tests, the compressor was operated for 220 h at saturated condition from 0.5 to 1.0 atm without any failure. High adiabatic efficiency (more than 60 %) is achieved with wide flow range (25-65 g/s) and the design value is fully satisfied. The compressor can rotate up to 80,000 rpm at maximum then the coil supply temperature of supercritical helium is 3.5 K. (author)

Superior MR images with electronically tuned and decoupled surface coils

International Nuclear Information System (INIS)

Ingwersen, H.; Freisen, L.; Friedrich, A.; Kess, H.; Krause, N.; Meissner, R.; Popp, W.

1987-01-01

In order to gain free positioning of surface coils in linearly polarized transmitting coils, it is absolutely necessary to electronically decouple both coils. For circularly polarized transmitting coils, decoupling is necessary in any case. In addition to the decoupling circuit automatic electronic tuning of the surface coils is used to gain the bast ratio of signal to noise. This combination of electronically decoupling and tuning of the surface coils yields intrinsic patient safety concerning local power deposition as well as free positioning and easy handling at the same time. Block diagrams, circuit schemes, and MR images obtained with several different surface coils are shown

Improved SNR of phased-array PERES coils via simulation study

International Nuclear Information System (INIS)

RodrIguez, Alfredo O; Medina, LucIa

2005-01-01

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. (note)

New technique for wiring SSC superconducting sextupole corrector coils

International Nuclear Information System (INIS)

Leon, B.

1985-01-01

There exists in the electronics industry, a technology for the manufacture of printed circuit (PC) boards which is directly transferable into the creation of highly controlled coils, such as the SSC sextupole superconducting corrector coils. This technology, which uses a process of laying down insulated wire in highly controlled patterns has heretofore been confined exclusively to the manufacture of high density printed circuit (PC) boards, possibly due to an ignorance of its utility in the field of precision winding of coils. This ability to fix wires in a well defined location can be used to produce precision wound coils in a very cost-effective manner. These coils may be superior in quality to conventionally made coils. Before describing what can be created with this technology, it is necessary to take a look at this coil winding process, the MULTIWIRE process, and the industry which has utilized this technology

Analysis and Optimization of Wireless Power Transfer Efficiency Considering the Tilt Angle of a Coil

Directory of Open Access Journals (Sweden)

Wei Huang

2018-01-01

Full Text Available Wireless power transfer (WPT based on magnetic resonant coupling is a promising technology in many industrial applications. Efficiency of the WPT system usually depends on the tilt angle of the transmitter or the receiver coil. This work analyzes the effect of the tilt angle on the efficiency of the WPT system with horizontal misalignment. The mutual inductance between two coils located at arbitrary positions with tilt angles is calculated using a numerical analysis based on the Neumann formula. The efficiency of the WPT system with a tilted coil is extracted using an equivalent circuit model with extracted mutual inductance. By analyzing the results, we propose an optimal tilt angle to maximize the efficiency of the WPT system. The best angle to maximize the efficiency depends on the radii of the two coils and their relative position. The calculated efficiencies versus the tilt angle for various WPT cases, which change the radius of RX (r2 = 0.075 m, 0.1 m, 0.15 m and the horizontal distance (y = 0 m, 0.05 m, 0.1 m, are compared with the experimental results. The analytically extracted efficiencies and the extracted optimal tilt angles agree well with those of the experimental results.

High voltage investigations for ITER coils

International Nuclear Information System (INIS)

Fink, S.; Fietz, W.H.

2006-01-01

The superconducting ITER magnets will be excited with high voltage during operation and fast discharge. Because the coils are complex systems the internal voltage distribution can differ to a large extent from the ideal linear voltage distribution. In case of fast excitations internal voltages between conductor and radial plate of a TF coil can be even higher than the terminal voltage of 3.5 kV to ground which appears during a fast discharge without a fault. Hence the determination of the transient voltage distribution is important for a proper insulation co-ordination and will provide a necessary basis for the verification of the individual insulation design and the choice of test voltages and waveforms. Especially the extent of internal overvoltages in case of failures, e. g. malfunction of discharge units and / or arcing is of special interest. Transient calculations for the ITER TF coil system have been performed for fast discharge and fault scenarios to define test voltages for ITER TF. The conductor and radial plate insulation of the ITER TF Model Coil were exposed at room temperature to test voltages derived from the results from these calculations. Breakdown appeared during the highest AC voltage step. A fault scenario for the TF fast discharge system is presented where one fault triggers a second fault, leading to considerable voltage stress. In addition a FEM model of Poloidal Field Coil 3 for the determination of the parameters of a detailed network model is presented in order to prepare detailed investigations of the transient voltage behaviour of the PF coils. (author)

A drift-pump coil design for a Tandem Mirror Reactor

International Nuclear Information System (INIS)

Neef, W.S.; Logan, B.

1983-01-01

This paper describes both the theory and mechanical design behind a new concept for trapped ion removal from tandem mirror end plugs. The design has been developed for the Mirror Advanced Reactor Study (MARS). The new drift-pump coils replace charge exchange pump beams. Pump beams consume large amounts of power and seriously reduce reactor performance. Drift-pump coils consume only a few megawatts of power and introduce no added burden to the reactor vacuum pumps. In addition, they are easy to replace. The coils are similar in shape to a paper clip and are located at two positions in each end plug. The coils between the transition coil and the first anchor yinyang serve to remove ions trapped in the magnetic well just outboard of the high field choke coil. The coils located between the anchor coil set and the plug coil set remove sloshing ions and trapped cold ions from the plug region

Design of Electromagnetic Moving-coil type Voice Coil Motor for Scanning mirror of Barcode reader

Energy Technology Data Exchange (ETDEWEB)

Shin, Bu Hyun; Lee, Jeong Woo; Shim, Hyun Ho; Park, Sang Goo [Hanbat National Univ., Daejeon (Korea, Republic of); Lee, Seung Yop [Sogang Univ., Seoul (Korea, Republic of)

2016-01-15

A voice coil actuator with moving coil type for scanning mirror system of barcode reader has been developed. The actuator has a simple structure including a magnet, a coil and a pin. The performance of the actuator is analyzed by a linearized theoretical model. And the dynamic performance of the proposed actuator is predicted through motor constant and restoring constant obtained by finite element simulations. The theoretical model was verified by the prototype which has 64 Hz resonance frequency and 60 deg reflecting angle. We also discovered that that 3 V input can make the actuator rotate over 61.8 deg reflecting angle at 50 Hz resonance frequency. The proposed actuator can simplify its driving configuration because of its implementation of open-loop control.

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

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Oliver Weinberger

Full Text Available 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.

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

Science.gov (United States)

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

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

Science.gov (United States)

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.

Stent-assisted coil embolization for cavernous carotid artery aneurysms.

Science.gov (United States)

Kono, Kenichi; Shintani, Aki; Okada, Hideo; Tanaka, Yuko; Terada, Tomoaki

2014-01-01

Internal carotid artery (ICA) occlusion with or without a bypass surgery is the traditional treatment for cavernous sinus (CS) aneurysms with cranial nerve (CN) dysfunction. Coil embolization without stents frequently requires retreatment because of the large size of CS aneurysms. We report the mid-term results of six unruptured CS aneurysms treated with stent-assisted coil embolization (SACE). The mean age of the patients was 72 years. The mean size of the aneurysms was 19.8 mm (range: 13-26 mm). Before treatment, four patients presented with CN dysfunction and two patients had no symptoms. SACE was performed under local or general anesthesia in three patients each. Mean packing density was 29.1% and tight packing was achieved. There were no neurological complications. CN dysfunction was cured in three patients (75%) and partly resolved in one patient (25%). Transient new CN dysfunction was observed in two patients (33%). Clinical and imaging follow-up ranged from 6 to 26 months (median: 16 months). Recanalization was observed in three patients (50%; neck remnant in two patients and dome filling in one patient), but no retreatment has yet been required. No recurrence of CN dysfunction has occurred yet. In summary, SACE increases packing density and may reduce requirement of retreatment with an acceptable cure rate of CN dysfunction. SACE may be a superior treatment for coiling without stents and be an alternative treatment of ICA occlusion for selected patients, such as older patients and those who require a high-flow bypass surgery or cannot receive general anesthesia.

Coil optimisation for transcranial magnetic stimulation in realistic head geometry.

Science.gov (United States)

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.

Effects of coil orientation on the electric field induced by TMS over the hand motor area

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